led unit for display and display device having the same

专利摘要:
A light-emitting device, including the first, second and third LED subunits and electrode pads arranged in the first LED subunit, electrically connected to the LED subunits and including a common electrode electrically connected to each of the first and first LED subunits, second and third electrode pads connected to a respective LED subunit, where the common electrode pad, the second electrode pad and the third electrode pad are electrically connected to the second LED subunit and the third LED subunit through holes that pass through the first LED subunit, the first, second and third LED subunits are configured to be triggered independently, the light generated in the first LED subunit emitted to the outside through the second and third LED subunits and the light generated in the second LED subunit it is emitted outwards through the third LED subunit.
公开号:BR112020010688A2
申请号:R112020010688-7
申请日:2018-11-27
公开日:2020-11-10
发明作者:Jong Hyeon Chae；Seong Gyu Jang；Ho Joon Lee；Chang Yeon Kim；Chung Hoon Lee
申请人:Seoul Viosys Co., Ltd.；
IPC主号:

专利说明:

[001] [001] Exemplary implementations of the invention generally refer to a display device and, more particularly, to a display device that has a pixel of light-emitting diode (LED) unit, a light-emitting device for a device of display and display device and a light emitting device for a display device with stacked structure of a plurality of LEDs and a display device having the same.
[002] [002] Light-emitting diodes have been used as an inorganic light source in several fields, such as display devices, automotive lamps and general lighting. With long life advantages, low power consumption and high response speed, the light emitting diode is rapidly replacing a conventional light source.
[003] [003] Meanwhile, a prior art light emitting diode has been used primarily as a backlight source in a display device. However, a micro LED display was recently developed as a next generation device that directly takes an image using light-emitting diodes.
[004] [004] In general, the display device implements various colors using mixed colors of blue, green and red. The display device includes a plurality of pixels to implement an image with various colors, and each pixel includes subpixels of blue, green and red. The color of a specific pixel is determined by the color of the subpixels, and the image is implemented by combining those pixels.
[005] [005] In the case of a micro LED, the micro LEDs corresponding to each subpixel are arranged in a two-dimensional plane. Therefore, it is necessary to have a large number of micro LEDs on a substrate. However, the micro LED is very small in size, with a surface area of 10,000 µm square or less and therefore there are several problems due to this small size. In particular, it is difficult to manipulate a small size LED and it is not easy to mount the LED on a display panel, especially in hundreds of thousands or millions, and replace a defective LED with micro LEDs mounted with a good LED.
[006] [006] In addition, as the subpixels are arranged in a two-dimensional plane, the area occupied by a pixel that includes subpixels of blue, green and red is relatively large. Therefore, to organize the subpixels within a limited area, it is necessary to reduce the area of each subpixel, causing deterioration in brightness by reducing the luminous area.
[007] [007] The information disclosed in this section is only for the understanding of the foundations of the inventive concepts and, therefore, may contain information that does not constitute the prior art.
[008] [008] Light emitting diodes built according to the principles and some exemplary implementations of the invention and displays using them are able to increase a light emitting area of each subpixel without increasing the pixel area.
[009] [009] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention provide high reliability due to a stable LED structure and simplified manufacturing process in which a single path can be connected to one or more semiconductor layers in each of the LED cells.
[010] [010] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention provide pixels that can be manufactured simultaneously to avoid the complicated process of individual assembly of the pixels.
[011] [011] Light emitting diodes and displays using light emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention, are capable of being activated in an active matrix manner.
[012] [012] Light emitting diodes and display using light emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention are able to reduce the time of the assembly process.
[013] [013] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention are able to prevent light interference between the LED cells by organizing the first , second and third LED batteries on top of each other to emit light with decreasing wavelengths. For example, the first, second and third LED batteries can emit red, green and blue light, respectively.
[014] [014] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention, are capable of suppressing the generation of secondary light between LED cells without the arrangement of color filters between them, which are usually formed between the LED cells to prevent the generation of secondary light by the light emitted by the adjacent LED cells.
[015] [015] Additional features of the inventive concepts will be presented in the description below and, in part, will be evident from the description or can be learned by practicing the inventive concepts.
[016] [016] Technical solution
[017] [017] A display device, according to an exemplary embodiment, includes a thin film transistor (TFT) substrate, a first LED subunit arranged on the TFT substrate, a second LED subunit arranged on the first LED subunit, a third LED subunit arranged in the second LED subunit, electrode pads arranged between the TFT substrate and the first LED subunit and connectors that connect the first, second and third LED subunits to a respective electrode pad, in which the first subunit LED, the second LED subunit and the third LED subunit are configured to be independently driven, the light generated from the first LED subunit is configured to be emitted to the outside of the display device passing through the second subunit of LED and the third LED subunit, and the light generated from the second LED subunit is configured to be emitted to the outside of the dis positive display, passing through the third LED subunit.
[018] [018] The first, second and third LED subunits can include a first LED battery, a second LED battery and a third LED battery, respectively, and the first, second and third LED batteries can be configured to emit light red, green light and blue light, respectively.
[019] [019] The display device may include a first reflective electrode disposed between the TFT substrate and the first LED subunit and in contact with a bottom surface of the first LED subunit, on which the connectors may include a first lower connector that connects the first electrode reflector for a first one of the electrode pads.
[020] [020] The connectors can also include a first upper connector connecting a top surface of the first LED subunit to a second of the electrode pads.
[021] [021] The display device may also include a second transparent electrode interposed between the first LED subunit and the second LED subunit and in ohmic contact with a lower surface of the second LED subunit and a third transparent electrode interposed between the second subunit LED and the third LED subunit and in ohmic contact with a lower surface of the third LED subunit, in which the connectors can also include a second lower connector that connects the second transparent electrode to the first of the electrode pads, a second upper connector connecting an upper surface of the second LED subunit to a third of the electrode pads, a third lower connector connecting the third transparent electrode to the first of the electrode pads and a third upper connector connecting an upper surface of the third LED subunit to a fourth of the electrode pads.
[022] [022] The first lower connector can be connected to an upper surface of the first reflective electrode, the second lower connector can be connected to an upper surface of the second transparent electrode and the third lower connector can be connected to an upper surface of the third transparent electrode .
[023] [023] The first upper connector can be connected to the upper surface of the first LED subunit, the second upper connector can be connected to the upper surface of the second LED subunit, the third upper connector can be connected to the upper surface of the third LED subunit and at least one of the upper connectors may be substantially annular in shape.
[024] [024] The connectors can also include intermediate connectors that connect the second upper connector and the third upper connector to the third and fourth electrode pads, respectively.
[025] [025] Each of the connectors can pass through at least one of the first, second and third LED subunits.
[026] [026] The first lower connector, the second lower connector and the third lower connector can be connected to the first of the electrode pads and the first upper connector, the second upper connector and the third upper connector can be connected to different electrode pads, respectively.
[027] [027] The first lower connector, the second lower connector and the third lower connector can be stacked on top of each other in the vertical direction, and the first upper connector, the second upper connector and the third upper connector can be pushed away from each other in the vertical direction and in a lateral direction.
[028] [028] The display device may further include a second transparent electrode interposed between the first LED subunit and the second LED subunit and in ohmic contact with a lower surface of the second LED subunit and a third transparent electrode interposed between the second subunit LED and the third LED subunit and in ohmic contact with a lower surface of the third LED subunit, in which the connectors can also include a second lower connector that connects the second transparent electrode to a third of the electrode pads, a second connector top connecting a top surface of the second LED subunit to the second of the electrode pads, a third bottom connector connecting the third transparent electrode to a fourth of the electrode pads and a third top connector connecting a top surface of the third LED subunit to the second of the electrode pads, and the first lower connector, the second lower connector ior and the third lower connector can be separated from each other and are connected to the first, third and fourth electrode pads, respectively, and the first upper connector, the second upper connector and the third upper connector can be electrically connected to the second pads electrode.
[029] [029] The first lower connector, the second lower connector and the third lower connector can be pushed away from each other in the vertical and lateral direction, and the first upper connector, the second upper connector and the third upper connector can be stacked on the vertical direction.
[030] [030] The display device may also include a first color filter interposed between the first LED subunit and the second LED subunit, and configured to transmit light generated from the first LED subunit and reflect the light generated from the second LED subunit, and a second color filter interposed between the second LED subunit and the third LED subunit, and configured to transmit light generated from the first and second LED subunits and reflect the light generated from the third subunit LED.
[031] [031] The display device may further include a first interlayer bonding layer between the TFT substrate and the first LED subunit, a second interlayer bonding layer between the first LED subunit and the second LED subunit and a third layer of interposed link between the second LED subunit and the third LED subunit, in which the second link layer is configured to transmit light generated from the first LED subunit and the third link layer is configured to transmit light generated from the first and second LED subunits.
[032] [032] The display device can be configured to operate in an active matrix manner.
[033] [033] The third lower connector and the third upper connector can be exposed by the third LED subunit in the plan view.
[034] [034] The first reflective electrode can be placed between the first LED subunit and the electrode pads.
[035] [035] The first, second and third LED subunits can include a micro LED with a surface area of less than about 10,000 µm square.
[036] [036] The first LED subunit can be configured to emit a red, green and blue light, the second LED subunit can be configured to emit a different light from red, green and blue than the first LED subunit, and the third subunit can be configured to emit a light other than red, green and blue from the first and second LED subunits.
[037] [037] A light-emitting device, according to an exemplary embodiment, includes a first LED subunit, a second LED subunit arranged adjacent to the first LED subunit, a third LED subunit arranged next to the second LED subunit, and electrode pads arranged in the first LED subunit and electrically connected to the first, second and third LED subunits, the electrode pads including a common electrode pad electrically connected to each of the first, second and third LED subunits, and first , second and third electrode pads connected to one of the respective first, second and third LED subunits, in which the common electrode pad, the second electrode pad and the third electrode pad are electrically connected to the second LED subunit and the third LED subunit through through holes that pass through the first LED subunit, the first LED subunit, the second subunit and LED and the third LED subunit are configured to be independently turned on, the light generated in the first LED subunit is configured to be emitted to the outside of the light emitting device through the second LED subunit and the third LED subunit. LED, and the light generated in the second LED subunit is configured to be emitted to the outside of the light emitting device through the third LED subunit.
[038] [038] The first, second and third LED subunits can include a first LED battery, a second LED battery and a third LED battery, respectively, and the first, second and third LED batteries can be configured to emit light red, green light and blue light, respectively.
[039] [039] The light emitting device may also include a first reflective electrode disposed between the electrodes and the first LED subunit and in ohmic contact with the first LED subunit, in which the common electrode pad is connected to the first reflective electrode.
[040] [040] The first reflective electrode may include an ohmic contact layer in ohmic contact with an upper surface of the first LED subunit and a reflective layer that covers the ohmic contact layer.
[041] [041] The first reflective electrode may have a hollow portion defined by a substantially annular element and the common electrode pad may pass through the hollow portion of the substantially annular element.
[042] [042] The light-emitting device may also include a second transparent electrode interposed between the second LED subunit and the third LED subunit and in ohmic contact with a lower surface of the second LED subunit and a third transparent electrode in ohmic contact with an upper surface of the third LED subunit, on which the common electrode pad can be electrically connected to the second transparent electrode and the third transparent electrode.
[043] [043] The common electrode pad can be connected to an upper surface of the second transparent electrode and to an upper surface of the third transparent electrode.
[044] [044] Each of the first LED subunit and the third LED subunit can include a first conductivity type semiconductor layer and a second conductivity type semiconductor layer arranged in a partial region of the first conductivity type semiconductor layer and the the first electrode pad and the third electrode pad can be electrically connected to the first conductivity type semiconductor layer of the first LED subunit and the third LED subunit, respectively.
[045] [045] The light emitting device may also include a first ohmic electrode disposed in the first conductivity type semiconductor layer of the first LED subunit, in which the first electrode pad is connected to the first ohmic electrode.
[046] [046] The third electrode pad can be connected directly to the first conductivity type semiconductor layer of the third LED subunit.
[047] [047] The light emitting device may also include a first color filter disposed between the third transparent electrode and the second LED subunit and a second color filter disposed between the first and the second LED subunits.
[048] [048] The first color filter and the second color filter can include layers of insulation with different refractive indices.
[049] [049] The common electrode pad and the third electrode pad can be electrically connected to the third LED subunit through holes that pass through the second LED subunit.
[050] [050] The light-emitting device may also include a substrate on which the third LED subunit is arranged.
[051] [051] The substrate can include a sapphire substrate or a gallium nitride substrate.
[052] [052] The light-emitting device may also include an insulation layer disposed between the first LED subunit and the electrode pads, in which the electrode pads are electrically connected to the first, second and third LED subunits through the insulating layer .
[053] [053] The insulation layer can include at least one of a distributed Bragg reflector and a light blocking material.
[054] [054] A display device can include a circuit board and a plurality of light-emitting devices arranged on the circuit board, at least some of the light-emitting devices can include the light-emitting device according to an exemplary embodiment, in the which the electrode pads can be electrically connected to the circuit board.
[055] [055] Each of the light-emitting devices can include a substrate coupled to the third LED subunit and the substrates of the light-emitting devices can be separated from each other.
[056] [056] A light-emitting device, according to an exemplary embodiment, includes a substrate, a first LED subunit arranged on the substrate, a second LED subunit arranged on the first LED subunit, a third LED subunit arranged on the second subunit LED and electrode pads electrically connected to the first, second and third LED subunits, the electrode pads including a common electrode pad electrically connected to each of the first, second and third LED subunits by a single pathway, and first, second and third electrodes connected to a respective of the first, second and third LED subunits.
[057] [057] The electrode pads can be arranged between the substrate and the first LED subunit, the through hole path can include a plurality of connectors connected to each of the first, second and third LED subunits and the connectors can include a first portion with a width greater than the width of the through hole path.
[058] [058] The first LED subunit can include a reflective electrode disposed on a lower surface of the same, and the reflective electrode can come in contact with the first portion of the corresponding connector.
[059] [059] The first, second and third LED subunits can be arranged between the electrode pads and the substrate, and the through hole path can be of a width that narrows in one direction from the electrode pads to the substrate.
[060] [060] The third LED subunit may include a reflective electrode on an upper surface of the same, and the common electrode pad may come in direct contact with the reflective electrode.
[061] [061] It should be understood that both the general description above and the detailed description below are exemplary and explanatory and are intended to provide additional explanations of the invention as claimed.
[062] [062] Light emitting diodes built according to the principles and some exemplary implementations of the invention and displays using them are able to increase a light emitting area of each subpixel without increasing the pixel area.
[063] [063] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention provide high reliability due to a stable LED structure and simplified manufacturing process in which a single path can be connected to one or more semiconductor layers in each of the LED cells.
[064] [064] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention provide pixels that can be manufactured simultaneously to avoid the complicated process of individual assembly of the pixels.
[065] [065] Light emitting diodes and displays using light emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention, are capable of being activated in an active matrix manner.
[066] [066] Light emitting diodes and displays using light emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention are able to reduce the time of the assembly process.
[067] [067] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention are able to prevent light interference between the LED cells by organizing the first , second and third LED batteries on top of each other to emit light with decreasing wavelengths. For example, the first, second and third LED batteries can emit red, green and blue light, respectively.
[068] [068] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, built according to the principles and some exemplary implementations of the invention, are capable of suppressing the generation of secondary light between LED cells without the arrangement of color filters between them, which are usually formed between the LED cells to prevent the generation of secondary light by the light emitted by the adjacent LED cells.
[069] [069] The accompanying drawings, which are included to provide an additional understanding of the invention and are incorporated and form part of this specification, illustrate exemplary embodiments of the invention and, together with the description, serve to explain the inventive concepts.
[070] [070] FIG. 1 is a schematic plan view of a display device according to an exemplary embodiment.
[071] [071] FIG. 2 is a schematic cross-sectional view taken along a line A-A of FIG. 1.
[072] [072] FIGS. 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6B, 7A, 7B, 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A, 13B, 14A, 14B, 15A, 15B, 16A and 16B are schematic plan views and schematic cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.
[073] [073] FIG. 17 is a schematic plan view of a display device according to another exemplary embodiment.
[074] [074] FIG. 18 is a schematic cross-sectional view taken along a line B-B of FIG. 17.
[075] [075] FIG. 19 is a schematic circuit diagram of a display device according to an exemplary embodiment.
[076] [076] FIG. 20 is a schematic plan view of a display device according to an exemplary embodiment.
[077] [077] FIG. 21A is a schematic plan view of a light emitting device according to an exemplary embodiment.
[078] [078] FIG. 21B is a schematic cross-sectional view along a line A-A of FIG. 21A.
[079] [079] FIGS. 22, 23, 24, 25, 26A, 26B, 27A, 27B, 28A, 28B, 29, 30A, 30B, 31A, 31B, 32A, 32B, 33A, 33B, 34A, 34B, 35A and 35B are schematic views and cross-sectional views illustrating a method of manufacturing a light-emitting device according to an exemplary embodiment.
[080] [080] FIG. 36 is a schematic cross-sectional view of a stack of LEDs for a display according to an exemplary embodiment.
[081] [081] FIGS. 37A, 37B, 37C, 37D and 37E are schematic cross-sectional views that illustrate a method of manufacturing a stack of light-emitting diodes for a display, according to an exemplary embodiment.
[082] [082] FIG. 38 is a schematic circuit diagram of a display device according to an exemplary embodiment.
[083] [083] FIG. 39 is a schematic plan view of a display device according to an exemplary embodiment.
[084] [084] FIG. 40 is an enlarged one-pixel plan view of the display device of FIG. 39.
[085] [085] FIG. 41 is a schematic cross-sectional view taken along a line A-A of FIG. 40.
[086] [086] FIG. 42 is a schematic cross-sectional view taken along a line B-B of FIG. 40.
[087] [087] FIGS. 43A, 43B, 43C, 43D, 43E, 43F, 43G, 43H, 43I, 43J and 43K are schematic cross-sectional views illustrating a method of manufacturing a display device, according to an exemplary embodiment.
[088] [088] FIG. 44 is a schematic circuit diagram of a display device according to another exemplary embodiment.
[089] [089] FIG. 45 is a schematic plan view of a display device according to another exemplary embodiment.
[090] [090] FIG. 46 is a schematic cross-sectional view of a stack of LEDs for a display according to an exemplary embodiment.
[091] [091] FIGS. 47A, 47B, 47C, 47D and 47E are schematic cross-sectional views that illustrate a method of manufacturing a stack of light-emitting diodes for a display according to an exemplary modality.
[092] [092] FIG. 48 is a schematic circuit diagram of a display device according to an exemplary embodiment.
[093] [093] FIG. 49 is a schematic plan view of a display device according to an exemplary embodiment.
[094] [094] FIG. 50 is an enlarged one-pixel plan view of the display device of FIG. 49.
[095] [095] FIG. 51 is a schematic cross-sectional view taken along a line A-A of FIG. 50.
[096] [096] FIG. 52 is a schematic cross-sectional view taken along a line B-B of FIG. 50.
[097] [097] FIGS. 53A, 53B, 53C, 53D, 53E, 53F, 53G, 53H, 53I, 53J and 53K are schematic cross-sectional views illustrating a method of manufacturing a display device, according to an exemplary embodiment.
[098] [098] FIG. 54 is a schematic circuit diagram of a display device according to another exemplary embodiment.
[099] [099] FIG. 55 is a schematic plan view of a display device according to another exemplary embodiment.
[0100] [0100] FIG. 56 is a schematic plan view of a display device according to an exemplary embodiment.
[0101] [0101] FIG. 57 is a schematic cross-sectional view of a LED pixel for a display in accordance with an exemplary embodiment.
[0102] [0102] FIG. 58 is a schematic circuit diagram of a display device according to an exemplary embodiment.
[0103] [0103] FIG. 59A and FIG. 59B are a top and bottom pixel view of a display device according to an exemplary embodiment.
[0104] [0104] FIG. 60A is a schematic cross-sectional view taken along a line A-A of FIG. 59A.
[0105] [0105] FIG. 60B is a schematic cross-sectional view taken along a line B-B of FIG. 59A.
[0106] [0106] FIG. 60C is a schematic cross-sectional view taken along a line C-C of FIG. 59A.
[0107] [0107] FIG. 60D is a schematic cross-sectional view taken along a D-D line of FIG. 59A.
[0108] [0108] FIGS. 61A, 61B, 62A, 62B, 63A, 63B, 64A, 64B, 65A, 65B, 66A, 66B, 67A, 67B, 68A and 68B are schematic plan views and schematic cross section views illustrating a method of fabricating a device display,
[0109] [0109] FIG. 69 is a schematic cross-sectional view of a LED pixel for a display, according to an exemplary embodiment.
[0110] [0110] FIG. 70 is an enlarged one-pixel view of a display device according to an exemplary embodiment.
[0111] [0111] FIG. 71A and FIG. 71B are seen in cross section taken along lines G-G and H-H in FIG. 70, respectively.
[0112] [0112] FIG. 72 is a schematic cross-sectional view of a stack of light emitting diode (LED) lights for a display according to an exemplary embodiment.
[0113] [0113] FIGS. 73A, 73B, 73C, 73D, 73E and 73F are schematic cross-sectional views that illustrate a method for making a light emitting diode stack for a display, according to an exemplary embodiment.
[0114] [0114] FIG. 74 is a schematic circuit diagram of a display device according to an exemplary embodiment.
[0115] [0115] FIG. 75 is a schematic plan view of a display device according to an exemplary embodiment.
[0116] [0116] FIG. 76 is an enlarged one-pixel plan view of the display device of FIG. 75.
[0117] [0117] FIG. 77 is a schematic cross-sectional view taken along a line A-A of FIG. 76.
[0118] [0118] FIG. 78 is a schematic cross-sectional view taken along a line B-B of FIG. 76.
[0119] [0119] FIGS. 79A, 79B, 79C, 79D, 79E, 79F, 79G and 79H are schematic plan views that illustrate a method for manufacturing a display device, according to an exemplary embodiment.
[0120] [0120] FIG. 80 is a schematic cross-sectional view of a stacked light-emitting structure, according to an exemplary embodiment.
[0121] [0121] FIGS. 81A and 81B are seen in cross section of a stacked light-emitting structure according to exemplary modalities.
[0122] [0122] FIG. 82 is a cross-sectional view of a stacked light-emitting structure including a wiring part, according to an exemplary embodiment.
[0123] [0123] FIG. 83 is a cross-sectional view of a stacked light-emitting structure, according to an exemplary embodiment.
[0124] [0124] FIG. 84 is a plan view of a display device, according to an exemplary embodiment.
[0125] [0125] FIG. 85 is an enlarged plan view of a portion P1 of FIG. 84.
[0126] [0126] FIG. 86 is a structural diagram of a display device, according to an exemplary embodiment.
[0127] [0127] FIG. 87 is a one-pixel circuit diagram of a passive display device.
[0128] [0128] FIG. 88 is a one-pixel circuit diagram of an active type display device.
[0129] [0129] FIG. 89 is a one-pixel plan view, according to an exemplary embodiment.
[0130] [0130] FIGS. 90A and 90B are cross-sectional views taken along lines I-I 'and II-II' of FIG. 89, respectively.
[0131] [0131] FIGS. 91A, 91B, and 91C are seen in cross section taken along line I-I 'in FIG. 89, illustrating a process of stacking the first to third epitaxial cells on a substrate according to an exemplary modality.
[0132] [0132] FIGS. 92, 94, 96, 98, 100, 102, 104 are plan views that sequentially illustrate a method of making a pixel on a substrate.
[0133] [0133] FIGS. 93A, 95A, 97A, 99A, 101A, 103A and 105A are seen in cross section taken along line I-I 'of FIGS. 92, 94, 96, 98, 100, 102, 104, respectively.
[0134] [0134] FIGS. 93B, 95B, 97B, 99B, 101B, 103B and 105B are seen in cross section taken along line II-II 'of FIGS. 92, 94, 96, 98, 100, 102, 104, respectively.
[0135] [0135] FIG. 106 is a schematic plan view of a display device according to an exemplary embodiment.
[0136] [0136] FIG. 107A is a cross-sectional view of the display device of FIG. 106.
[0137] [0137] FIG. 107B is a schematic circuit diagram of a display device according to an exemplary embodiment.
[0138] [0138] FIGS. 108A, 108B, 108C, 108D, 108E, 109A, 109B, 109C, 109D, 109E, 110A, 110B, 110C, 110D, 111A, 111B, 111C, 111D, 112A, 112B, 112C, 112D, 113A, 113B and 114 are schematic plan views and cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.
[0139] [0139] FIGS. 115A, 115B and 115C are schematic cross-sectional views of a metal bonding material according to exemplary embodiments. Modalities of the Invention
[0140] [0140] In the following description, for the sake of explanation, several specific details are presented in order to provide a complete understanding of various exemplary embodiments or implementations of the invention. As used here, "modalities" and "implementations" are interchangeable words that are non-limiting examples of devices or methods that employ one or more of the inventive concepts disclosed herein. It is apparent, however, that several exemplary modalities can be practiced without these specific details or with one or more equivalent arrangements. In other cases, known structures and devices are shown in the form of a block diagram to avoid unnecessarily obscuring several exemplary modalities. In addition, several exemplary modalities may be different, but need not be exclusive. For example, forms, configurations and specific characteristics of an exemplary modality can be used or implemented in another exemplary modality without departing from inventive concepts.
[0141] [0141] Unless otherwise specified, the illustrated exemplary modalities are to be understood as providing exemplary characteristics of varying details in some ways in which inventive concepts can be implemented in practice. Therefore, unless otherwise specified, resources, components, modules, layers, films, panels, regions and / or aspects, etc. (hereinafter, individually or collectively referred to as "elements"), the various modalities can be combined in another way, separated, exchanged and / or reorganized without departing from the inventive concepts.
[0142] [0142] The use of cross hatching and / or shading in the accompanying drawings is generally provided to clarify the boundaries between adjacent elements. As such, neither the presence nor the absence of hatching or shading transmit or indicate any preference or requirement for materials, properties, dimensions, proportions, similarities between illustrated elements and / or any other characteristic, attribute, property, etc., of the elements , unless specified. In addition, in the attached drawings, the size and relative size of the elements may be exaggerated for reasons of clarity and / or description. When an exemplary modality can be implemented differently, a specific process order can be carried out differently from the order described. For example, two processes described consecutively can be performed at substantially the same time or performed in an order opposite to the order described. In addition, similar reference numbers indicate similar elements.
[0143] [0143] When an element such as one or layer is referred to as "above", "connected to" or "attached to" or another element or layer, it can be directly on, connected to or attached to another element or layer or elements or intervening layers may be present. When, however, an element or layer is referred to as "directly in", "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. Finally, the term “connected” can refer to physical, electrical and / or fluid connections, with or without intervening elements, and the D1 axis, the D2 axis and the D3 axis are not limited to three axes of a rectangular coordinates, such as x, y, and z axes, and can be interpreted in a broader sense, for example, the D1 axis, the D2 axis, and the D3 axis can be perpendicular to each other or can represent different directions that are not perpendicular to each other other for the purposes of ta disclosure, "at least one of X, Y and Z" and "at least one selected from the group consisting of X, Y and Z" can be interpreted as only X, only Y, only Z, or any combination of two or more than X, Y and Z, such as XYZ, XYY, YZ and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.
[0144] [0144] Although the terms "first", "second" etc. can be used here to describe various types of elements, these elements should not be limited by those terms. These terms are used to distinguish one element from another element. Thus, a first element discussed below could be called a second element without departing from the teachings of disclosure.
[0145] [0145] Spatially relative terms, such as "below", "below", "under", "lower", "above", "upper", "above", "above", "highest", "lateral" ( for example, as in the "side wall"), and the like, can be used here for descriptive purposes and, thus, to describe an element related to other elements, as illustrated in the drawings. Spatially relative terms are intended to cover different orientations of a device in use, operation and / or manufacture, in addition to the orientation represented in the drawings. For example, if the device in the drawings is flipped, the elements described as "below" or "under" other elements or features will be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass an orientation above and below. In addition, the device can be otherwise oriented (for example, rotated 90 degrees or in other orientations) and, as such, the spatially relative descriptors used herein interpreted accordingly.
[0146] [0146] The terminology used in this document is intended to describe particular modalities and is not intended to be limiting. As used in this document, the singular forms "one", "one" and "o / a" are also intended to include plural forms, unless the context clearly indicates otherwise. In addition, the terms "comprises", "comprising", "includes" and / or "including", when used in this specification, specify the presence of declared resources, integers, steps, operations, elements, components and / or groups, but it does not exclude the presence or addition of one or more resources, integers, steps, operations, elements, components and / or groups thereof. Note also that, as used in this document, the terms "substantially", "about" and other similar terms are used as approximation terms and not as terms of degree and, as such, are used to account for inherent deviations in values measured, calculated and / or supplied that would be recognized by a person skilled in the art.
[0147] [0147] Several exemplary modalities are described here with reference to sectional and / or exploded illustrations which are schematic illustrations of idealized exemplary modalities and / or intermediate structures. As such, variations in the shapes of the illustrations are expected as a result, for example, of manufacturing techniques and / or tolerances. Thus, exemplary modalities disclosed in this document should not necessarily be interpreted as limited to the particular illustrated shapes of the regions, but should include deviations in the shapes that result, for example, from manufacturing. In this way, the regions illustrated in the drawings may be schematic in nature and the shapes of these regions may not reflect the actual shapes of the regions of a device and, as such, are not necessarily intended to be limiting.
[0148] [0148] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meanings as those commonly understood by a specialist in the subject to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant technique and should not be interpreted in an ideal or excessively formal manner unless expressly defined here.
[0149] [0149] As used herein, a light-emitting device or a light-emitting diode according to exemplary modalities may include a micro LED, which has a surface area of less than about 10,000 µm square, as known in the art. In other exemplary embodiments, micro LEDs can have a surface area of less than about
[0150] [0150] FIG. 1 is a schematic plan view of a display device according to an exemplary embodiment. FIG. 2 is a schematic cross-sectional view taken along a line A-A of FIG. 1.
[0151] [0151] Referring to FIGS. 1 and 2, the display device may include a substrate 51, electrode pads 53a, 53b, 53c and 53d, a first battery of LED 23, a second battery of LED 33, a second battery of LED 33, a third battery of LED 43, a first reflective electrode 25, a second transparent electrode 35, a third transparent electrode 45, a first color filter 37, a second color filter 47, a first connection layer 55, a second connection layer 65 and a third connection layer 75. In addition, the display device may include a plurality of connectors 59a, 59b, 59c, 59d, 69b, 69c, 69d, 79c and 79d and insulation layers 57, 67 and 77. As used herein, a connector can be any type of structure, including through holes, paths, wires, lines, conductive material and the like, which serve to connect two elements, like layers, electrically and / or mechanically.
[0152] [0152] Substrate 51 supports LED batteries 23, 33 and 43. In addition, substrate 51 may have an internal circuit. For example, substrate 51 may be a silicon substrate on which thin film transistors are formed. TFT substrates have been widely used in display fields, such as LCD display fields, to actively activate a display device. Since TFT substrates are well known in the art, detailed descriptions of a TFT substrate structure will be omitted.
[0153] [0153] Although FIGS. 1 and 2 show a unit pixel arranged on substrate 51, a plurality of unit pixels can be arranged on substrate 51, and the plurality of unit pixels can be driven in an active matrix manner.
[0154] [0154] The electrode pads 53a, 53b, 53c and 53d are exposed on substrate 51. Each of the electrode pads 53a, 53b, 53c and 53d is connected to one of the sub pixels of the unit pixel arranged on substrate 51, but the pad electrode 53d is connected to each of the three subpixels. Each of the electrode pads 53a, 53b, 53c and 53d can be connected to the internal circuit of the substrate 51.
[0155] [0155] The first LED stack 23, the second LED stack 33 and the third LED stack 43 include a n-type semiconductor layer, a p-type semiconductor layer and an active layer interposed between them. The active layer can have a multi-quantum well structure.
[0156] [0156] The closer to substrate 51, the longer the wavelength of light can be emitted from the LED cells. For example, the first stack of LED 23 can be an inorganic light-emitting diode configured to emit red light, the second LED stack 33 can be an inorganic light-emitting diode configured to emit green light, and the third stack of LED 43 can be an inorganic light emitting diode configured to emit blue light. The first LED stack 23 may include a GaInP based well layer and the second LED stack 33 and the third LED stack 43 may include a GaInN based well layer. However, the inventive concepts are not limited to this, and when the pixel includes a micro LED, the first battery of LED 23 can emit any red light, green light and blue light, and the second and third batteries of LED 33 and 43 they can emit different red, green and blue light, without adversely affecting the operation due to the small form factor of a micro LED.
[0157] [0157] The surfaces of each of the LED cells 23, 33 and 43 are a n-type semiconductor layer and a p-type semiconductor layer, respectively. In the following, an upper and lower surface of each of the first to third LED batteries 23, 33 and 43 will be described as a type n and a type p, respectively. However, the inventive concepts are not limited to these, and the type of the top surface and the bottom surface of each LED battery can be reversed or modified in several ways.
[0158] [0158] When the top surface of the third stack of LED 43 is type n, the top surface of the third stack of LED 43 may have a textured surface by chemical etching or the like to form a rough surface. The upper surfaces of the first LED stack 23 and the second LED stack 33 can also be subject to surface texturing. However, when the second LED 33 battery emits green light, since the green light has greater visibility than the red light and the blue light, it may be preferable to increase the light emission efficiency of the first LED battery 23 and the third LED stack 43 to a greater extent than the second LED stack 33. As such, the first LED stack 23 and the third LED stack 43 can have a textured surface to improve the efficiency of light extraction without texturing the surface of the second LED stack 33. In this way, the intensities of red light, green light and blue light can be balanced and adjusted to have substantially similar levels.
[0159] [0159] The first battery of LED 23 is disposed near the support substrate 51, the second battery of LED 33 is disposed in the first battery of LED 23 and the third battery of LED 43 is disposed in the second battery of LED 33. Once Since the first LED battery 23 can emit light with a wavelength greater than the second and third LED batteries 33 and 43, the light generated in the first LED battery 23 can be transmitted through the second and third LED batteries 33 and 43 and issued abroad. In addition, since the second LED battery 33 can emit light with a longer wavelength than the third LED battery 43, the light generated from the second LED battery
[0160] [0160] The first reflective electrode 25 is in ohmic contact with the p-type semiconductor layer of the first LED stack 23 and reflects the light generated from the first LED stack
[0161] [0161] The ohmic contact layer 25a is partially in contact with the p-type semiconductor layer. In order to prevent the absorption of light by the ohmic contact layer 25a, the ohmic contact layer 25a can be formed in a predetermined area. For example, the ohmic contact layer 25a can be arranged near an edge of the first LED stack 23 and can be substantially arranged in an annular shape. A contact area of the ohmic contact layer 25a in relation to the first LED stack 23 can be 25% or less, or it can be 10% or less in some exemplary embodiments. Even though the contact area of the ohmic contact layer 25a is relatively small, when an area of the first LED stack 23 is about 200 µm or less, a current can be evenly distributed in the first LED stack 23. The contact layer ohmic 25a can be formed by transparent conductive oxides or Au alloys, such as Au (Zn) or Au (Be).
[0162] [0162] Reflective layer 25b can cover the ohmic contact layer 25a and the bottom surface of the first LED stack 23. However, as shown in Fig. 1, the reflective layer 25b exposes the bottom surface of the first LED stack 23 in regions around which connectors 59a, 59b, 59c and 59d are to be formed. More particularly, the reflective layer 25b can expose the bottom surface of the first LED stack 23 in a region surrounded by the ohmic contact layer 25a. The reflective layer 25b can include a reflective metal layer formed by Al, Ag or others. In addition, the reflective layer 25b may include a metal adhesion layer formed by Ti, Ta, Ni, Cr or others on the upper and lower surfaces of the reflective metal layer, in order to improve the adhesion of the reflective metal layer. The reflective layer 25b can be formed by a metal layer, which has a high reflectance for the light generated from the first LED stack 23, for example, red light. Meanwhile, the reflective layer 25b may have a relatively low reflectance for the light generated from the second battery of LED 33 or the third battery of LED 43, for example, green light or blue light. Therefore, the reflective layer 25b can reduce light interference by absorbing the light generated from the second and third LED batteries 33 and 43 that is emitted towards the support substrate 51. The Au has high reflectance for red light and low reflectance for green light or blue light and therefore can be used to form the reflective layer 25b arranged in the first stack of LED 23.
[0163] [0163] The second transparent electrode 35 is in ohmic contact with the p-type semiconductor layer of the second LED stack 33. The second transparent electrode 35 can be formed by a metal layer or conductive oxide layer transparent to red light and light green. The third transparent electrode 45 is in ohmic contact with the p-type semiconductor layer of the third LED stack 43. The third electrode 45 can be formed by a metal layer or oxide layer transparent to red light, green light and blue light . The second transparent electrode 35 and the third transparent electrode 45 may be in ohmic contact with the p-type semiconductor layer of each of the LED cells to aid in current distribution. Examples of the conductive oxide layer used for the second and third transparent electrodes 35 and 45 can include SnO2, InO2, ITO, ZnO, IZO or others.
[0164] [0164] The first color filter 37 can be disposed between the first battery of LED 23 and the second battery of LED 33. In addition, the second color filter 47 can be disposed between the second battery of LED 33 and the third battery LED 43. The first color filter 37 can transmit light generated from the first stack of LED 23 and reflects the light generated from the second LED stack 33. The second color filter 47 can transmit light generated from the first and second batteries of LED 23 and 33, and reflects the light generated from the third battery of LED 43. As such, the light generated from the first battery of LED 23 can be emitted to the outside through the second battery of LED 33 and the third battery of LED 43 and the light generated from the second LED 33 battery can be emitted to the outside via the third LED 43 battery. In addition, it may be possible to prevent the light generated from the second LED 33 battery from being incident on the first battery of LED 23 and get lost, or prevent the light generated from the third LED stack 43 is incident on the second LED stack 33 and is lost.
[0165] [0165] In some exemplary embodiments, the first color filter 37 can also reflect the light generated from the third LED stack 43.
[0166] [0166] The first and second color filters 37 and 47 can be, for example, a low pass filter through which only a region of low wavelength light, for example, light in a region of wavelength long, a bandpass filter through which only a certain wavelength region of the light passes or a bandwidth filter only blocks a particular wavelength region of the light. More particularly, the first and second color filters 37 and 47 can be formed by alternately stacking layers of insulation with different refractive indices. For example, color filters can be formed by alternately stacking TiO2 and SiO2. The first and second color filters 37 and 47 can include a distributed Bragg reflector (DBR). An interruption band in the distributed Bragg reflector can be controlled by adjusting the thicknesses of TiO2 and SiO2. The low-pass filter and the band-pass filter can also be formed by stacking layers of insulation alternately with different refractive indices one above the other.
[0167] [0167] The first connection layer 55 couples the first LED stack 23 to the substrate 51. As shown in the drawings, the first reflective electrode 25 can be in contact with the first connection layer 55. The first connection layer 55 can be transmissive or non-transmissive.
[0168] [0168] The second connection layer 65 couples the second battery of LED 33 to the first battery of LED 23. As shown in the drawings, the second connection layer 65 can be in contact with the first battery of LED 23 and the first filter of color 37. The second connection layer 65 transmits light generated from the first LED stack 23. The second connection layer 65 can be formed of, for example, spin-on-glass with light transmitting property.
[0169] [0169] The third connection layer 75 couples the third battery of LED 43 to the second battery of LED 33. As shown in the drawings, the third connection layer 75 can be in contact with the second battery of LED 33 and the second filter of color 47. However, the inventive concepts are not limited to these and a transparent conductive layer can be arranged on the second LED stack 33. The third link layer 75 transmits the light generated from the first LED stack 23 and the second LED stack 33. The third connection layer 75 can be formed, for example, of spin-on-glass with light transmitting property.
[0170] [0170] The connecting layers 55, 65 and 75 can be formed by forming transparent organic layers or transparent inorganic layer in each of the two objects to be connected and then connecting the objects to each other. Examples of an organic layer can include SU8, poly (methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB) or others. Examples of an inorganic layer can include Al2O3, SiO2, SiNx or others. The organic layers can be bonded under high vacuum and high pressure. The surfaces of inorganic layers can be planarized by, for example, a mechanical chemical polishing (CMP), and then the energy of the surface is reduced by plasma and the like, resulting in high vacuum bonding.
[0171] [0171] A first connector 59d electrically connects the first reflective electrode 25 and the electrode pad 53d to each other. As such, the first connector 59d is electrically connected to the bottom surface of the first LED stack 23. As shown in the drawings, the first connector 59d can pass through the first LED stack 23. However, the inventive concepts are not limited these and the first connector 1 59d can be formed on a side surface of the first stack of LED 23. Insulation layer 57 is interposed between the first connector 1 59d and the first stack of LED 23, thereby preventing the first connector 1 59d short-circuit
[0172] [0172] A first connector 2 59a electrically connects the top surface of the first LED stack 23 and the electrode pad 53a on substrate 51 to each other. The first connector 2 59a can be connected to the top surface of the first battery of LED 23 and can pass through the first battery of LED 23 to be connected to the electrode pad 53a. The insulation layer 57 can be interposed between the first LED stack 23 and the first connector 2 59a, in order to prevent the first connector 2 59a from short-circuiting the bottom surface of the first LED stack 23.
[0173] [0173] A first connector 3 59b and a first connector 4 59c can pass through the first stack of LED 23 to be connected to each of the electrode pads 53b and 53c. The first connector 3 59b and the first connector 4 59c are isolated from the first LED stack 23, by the insulation layer 57 interposed between the first LED stack 23 and the connectors 59b and 59c.
[0174] [0174] The first connector 3 59b and the first connector 4 59c can function as an intermediate connector or these configurations can be omitted in some exemplary modalities.
[0175] [0175] A second connector 69d is arranged to electrically connect the second transparent electrode 35 to the electrode pad 53d. The second connector 69d is electrically connected to the bottom surface of the second battery of LED 33 through the second transparent electrode 35. As shown in the drawings, the second connector 69d can pass through the second battery of LED 33. However, the inventive concepts are not limited to these and the second connector 1 69d can be formed on a side surface of the first stack of LED 33. Insulation layer 67 is interposed between the second connector 1 69d and the second stack of LED 33, thereby preventing the second connector 1d 69d to short-circuit the upper surface of the second LED stack 33.
[0176] [0176] As shown in Fig. 2, the second connector 1 69d can be connected to the first connector 1 59d to be electrically connected to the electrode pad 53d. In this case, the first connector 59d can function as an intermediate connector. In addition, as shown in FIG. 2, the second connector 1 69d can be stacked on the first connector 1 59d in the vertical direction.
[0177] [0177] A second connector 2b 69b is arranged to electrically connect the upper surface of the second battery of LED 33 to the electrode pad 53b. The second connector 2 69b can be connected to the top surface of the second battery of LED 33 and can pass through the second battery of LED 33. As shown in the drawings, the second connector 2 69b can be connected to the first connector 3 59b to be electrically connected to the 53b electrode pad. The second connector 2 69b can be directly connected to the electrode pad 53b. In that case, the first connector 59b is omitted.
[0178] [0178] The insulation layer 67 can be interposed between the second battery of LED 33 and the second connector 2 69b, in order to prevent the second connector 2 69b from being short-circuited on the bottom surface of the second battery of LED 33.
[0179] [0179] A second connector 3 69c can be arranged to pass through the second stack of LED 33. The second connector 3 69c can be electrically connected to the electrode pad 53c and can be connected, for example, to the first connector 4 59c. The second connector 3 69c is isolated from the second battery of LED 33 by the insulation layer 67 interposed between the second battery of LED 33 and the second connector 3 69c.
[0180] [0180] The second connector 69c can function as an intermediate connector, or these configurations can be omitted in some exemplary modalities.
[0181] [0181] A third connector 1 79d is arranged to connect the third transparent electrode 45 and the electrode pad 53d to each other. The third connector 1 79d is electrically connected to the bottom surface of the third battery of LED 43 through the third transparent electrode 45. As shown in the drawings, the third connector 1 79d can pass through the third battery of LED 43. However, the inventive concepts are not limited to these, and the third connector 1 79d can be formed on a side surface of the third LED stack
[0182] [0182] As shown in Fig. 2, the third connector 1 79d can be connected to the second connector 1 69d to be electrically connected to the electrode pad 53d. In this case, the second connector 1 69d and the first connector 1 59d can function as an intermediate connector. In addition, as shown in FIG. 2, the third connector 1 79d can be stacked on the second connector 1 69d in the vertical direction. Therefore, the first connector 1 59d, the second connector 1 69d and the third connector 1 79d are electrically connected to each other and are stacked in the vertical direction. The connectors are arranged in the direction of the light emission to absorb the light. In a case where the connectors are arranged to be spaced apart from each other in a lateral direction, an area of light emission can be reduced and cause greater loss of light. However, the connectors, according to an exemplary embodiment, are stacked in the vertical direction to reduce the loss of light generated from the first LED stack 23 and the second LED stack 33 by the connectors.
[0183] [0183] A third connector 2c 79c is arranged to connect the top surface of the third stack of LED 43 and the electrode pad 53c to each other. The third connector 2 79c can be connected to the top surface of the third stack of LEDs 43 and can pass through the third stack of LED 43. As shown in the drawings, the third connector 2 79c can be connected to the second connector 3 69c to be electrically connected electrode pad 53c. The third connector 2 79c can be connected directly to electrode 53c. In this case, the second connector 3 69c is omitted.
[0184] [0184] Meanwhile, the insulation layer 77 can be interposed between the third stack of LED 43 and the third connector 2 79c, in order to prevent the third connector 2 79c from being short-circuited on the bottom surface of the third pile of LED 43.
[0185] [0185] As shown in the drawings, the third connector 2 79c, the second connector 3 69c and the first connector 4 59c can be stacked in the vertical direction, which can reduce light loss.
[0186] [0186] To prevent light interference between pixels due to light emission from the first LED 23 battery, the second LED 33 battery and the third LED battery 43 to the side surfaces of the same, a light reflecting layer or a layer of light blocking material can be formed to cover the side surfaces of the first to third LED stacks 23, 33 and 43. Examples of the light reflecting layer may include a distributed Bragg reflector or an insulating layer formed of SiO2 with a reflective metal layer or a highly reflective organic layer deposited on the insulating layer. As a light blocking layer, for example, black epoxy can be used. Light-blocking materials prevent light interference between light-emitting elements to increase the contrast ratio of an image.
[0187] [0187] According to an exemplary embodiment, the first LED battery 23 is electrically connected to the electrode pads 53d and 53a, the second LED battery 33 is electrically connected to the electrode pads 53d and 53b and the third LED battery 43 is electrically connected to the electrode pads 53d and 53c. As such, the anodes of the first LED stack 23, the second LED stack 33 and the third LED stack 43 are commonly electrically connected to the electrode pad 53d, and their cathodes are electrically connected to the electrode pads 53a, 53b and 53c different from each other, respectively. Therefore, the first to third LED batteries 23, 33 and 43 can be activated independently. In addition, these LED cells 23, 33 and 43 can be arranged on the thin film transistor substrate 51 and can be electrically connected to the internal circuit of the substrate 51 to be activated in an active matrix manner.
[0188] [0188] FIGS. 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6B, 7A, 7B, 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A, 13B, 14A, 14B, 15A, 15B, 16A and 16B are schematic plan views and schematic cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment. In the drawings, each plan view corresponds to a plan view of FIG. 1 and each cross-sectional view is taken along a line A-A of FIG. 1.
[0189] [0189] First, with reference to FIGS. 3A and 3B, a first LED stack 23 is grown on a first substrate 21. The first substrate 21 can be, for example, a GaAs substrate. In addition, the first LED stack 23 consists of semiconductor layers based on AlGaInP and includes a n-type semiconductor layer, an active layer and a p-type semiconductor layer.
[0190] [0190] An ohmic contact layer 25a and a reflective layer 25b are formed on the first LED stack 23 to form a first reflective electrode 25. The ohmic contact layer 25a can be formed using the lifting technique or the like, and can be formed to be arranged near an edge of the first stack of LEDs 23. As shown in the drawings, the ohmic contact layer 25a can be formed to be substantially annular in shape.
[0191] [0191] Reflective layer 25b covers the ohmic contact layer 25a and also covers the first LED stack 23. Reflective layer 25b can be formed to expose each edge of the first LED stack 23. More particularly, the layer reflector 25b can have an opening 25h exposing the first stack of LED 23 with the ohmic contact layer 25a. The reflective layer 25b can be, for example, formed from Au and can be formed using a lifting technique or the like.
[0192] [0192] Referring to FIGS. 4A and 4B, a second stack of LED 33 is grown on a second substrate 31 and a second transparent electrode 35 and a first color filter 37 are formed on the second stack of LED 33. The second stack of LED 33 can be formed by layers of semiconductors based on gallium nitride and may include a well layer based on GaInN. The second substrate 31, in which the gallium nitride-based semiconductor layers can be grown is different from the first substrate 21. A proportion of GaInN composition can be determined so that the second LED stack 33 emits green light. Meanwhile, the second transparent electrode 35 is in ohmic contact with the second type p semiconductor layer.
[0193] [0193] Referring to FIGS. 5A and 5B, a third LED stack 43 is grown on a third substrate 41 and a third transparent electrode 45 and a second color filter 47 are formed on the third LED stack 43. The third LED stack 43 can be formed by layers semiconductors based on gallium nitride and may include a well layer based on GaInN. The third substrate 41, on which the gallium nitride-based semiconductor layers can be grown is different from the first substrate 21. A GaInN composition ratio can be determined so that the third LED stack 43 emits blue light. Meanwhile, the third transparent electrode 45 is in ohmic contact with the second semiconductor p-type layer.
[0194] [0194] The first color filter 37 and the second color filter 47 are substantially the same as those described with reference to FIG. 1 and therefore detailed descriptions will be omitted to avoid redundancy.
[0195] [0195] Referring to FIGS. 6A and 6B, the electrode pads 53a, 53b, 53c and 53d are formed on a substrate 51. The substrate 51 can be a substrate formed from Si, with thin film transistors on it. Each of the electrode pads 53a, 53b, 53c and 53d corresponding to a pixel area can be arranged in each of the four edge regions of the substrate 51.
[0196] [0196] The first stack of LED 23, the second stack of LED 33, the third stack of LED 43 and the electrode pads 53a, 53b, 53c and 53d are formed separately on different substrates, and the sequence of formation of the same does not it is particularly limited.
[0197] [0197] Referring to FIGS. 7A and 7B, the first stack of LED 23 is coupled to substrate 51 through a first bonding layer 55. The first bonding layer 55 can be arranged on substrate 51, and the first reflecting electrode 25 is arranged to face substrate 51 , so that the first reflective electrode 25 is connected to the first bonding layer 55. Alternatively, the layers of bonding material can be formed on each of the substrates 51 and on the first stack of LEDs 23 and then the first stack LED 23 can be coupled to substrate 51, connecting the layers of bonding material together. Meanwhile, the first substrate 21 can be removed from the first stack of LED 23 by chemical etching, or the like. As such, the n-type semiconductor layer of the first LED stack 23 is exposed on the top surface. The exposed n semiconductor layer can be subjected to surface texturing.
[0198] [0198] Referring to FIGS. 8A and 8B, the first LED stack 23 is standardized to expose a part of the first reflective electrode 25. To avoid damage to the reflective layer 25b, the ohmic contact layer 25a can be exposed. In addition, the first LED stack 23 and the first connection layer 55 are standardized to form openings to expose the electrode pads 53a, 53b, 53c and 53d.
[0199] [0199] Referring to FIGS. 9A and 9B, an insulating layer 57 is formed to cover the side surfaces of the first stack of LEDs 23 in the openings. The insulation layer 57 can also partially cover the upper surfaces of the third LED stack 23. The insulation layer 57 is formed to expose the first reflective electrode 25 and the impact pads 53a, 53b, 53c and 53d.
[0200] [0200] Referring to FIGS. 10A and 10B, connectors 59a, 59b, 59c and 59d are formed, which can be connected to the exposed electrode pads 53a, 53b, 53c and 53d, respectively. A first connector 1 59d is connected to the first reflective electrode 25 and also to the electrode pad 53d. Therefore, a bottom surface of the first LED stack 23 and the electrode pad 53d are electrically connected to each other by the first connector 1 59d. In addition, a first connector 2 59a is connected to the top surface of the first LED stack 23 and also to the electrode pad 53a. Therefore, the upper surface of the first LED stack 23 and the electrode pad 53a are electrically connected to each other by the first connector 2 59a. The first connector 3 59b and a first connector 4 59c are electrically isolated from the first LED stack 23 by the insulation layer 57.
[0201] [0201] Referring to FIGS. 11A and 11B, the second LED stack 33 of FIGS. 4A and 4B is coupled to the first LED stack 23, in which the first 1, 2, 3 and 4 connectors 59d, 59a, 59b and 59c are formed, through a second connection layer 65. The first color filter 37 is connected to the second link layer 65 and arranged to face the first LED stack 23. The link layer 65 can be arranged in the first LED stack 23 in advance. The first color filter 37 can be connected to the second connection layer 65 and arranged to face the second connection layer 65. Alternatively, the layers of connection material can be formed in each of the first LED stack 23 and the first filter color 37, and the layers of bonding material are connected together to couple the second LED stack 33 to the first LED stack 23. Meanwhile, the second substrate 31 can be separated from the second LED stack 33 by a process laser or chemical lift or other. Therefore, the n-type semiconductor layer of the second LED stack 33 is exposed. The semiconductor layer of the exposed type can be subjected to surface texturing by chemical etching or the like. However, the step of texturing the surface in the second stack of LED 33 can be omitted in some exemplary embodiments.
[0202] [0202] Referring to FIGS. 12A and 12B, the second LED stack 33 is standardized to expose the second transparent electrode 35 and the second exposed transparent electrode 35, the first color filter 37 and the second connection layer 65 are etched to form openings to expose the first connector 1 59d. In addition, the openings for exposing the first connector 3 59b and the first connector 4 59c can be formed together.
[0203] [0203] Referring to FIGS. 13A and 13B, an insulating layer 67 covering the sides of the exposed openings is formed. The insulation layer 67 exposes the second transparent electrode 35 and also exposes the first connector 1 59d, the first connector 3 59b and the first connector 4 59c.
[0204] [0204] A second connector 1 69d, a second connector 2 69b and a second connector 3 69c are formed in the openings. The second connector 1 69d electrically connects the second transparent electrode 35 and the first connector 1 59d to each other and is isolated from the top surface of the second stack of LEDs 33 by the insulating layer 67. The second connector 2 69b is connected to the top surface of the second LED stack 33 and the first connector 3 59b. The second connector 2 69b is electrically connected to electrode 53b through the first connector 3 59b. The second connector 2 69b is electrically connected to the bottom surface of the second LED stack 33 and the second transparent electrode 35 by the insulation layer 67.
[0205] [0205] Meanwhile, the second connector 3 69c is connected to the first connector 4 59c and is isolated from the second battery of LED 33 and the second transparent electrode 35 by the insulation layer 67.
[0206] [0206] Referring to FIGS. 14A and 14B, the third LED stack 43 of FIGS. 5A and 5B is coupled to the second LED stack 33, in which the second, second, second and third 3 connectors 69d, 69b and 69c are formed through a third connection layer 75. The second color filter 47 is connected to the third connection layer 75 and arranged to face the second pile of LED 33. The third connection layer 75 can be arranged in the second pile of LED 33 in advance, and the second color filter 47 can be connected to the third connection layer 75 and arranged to face the third bonding layer 75. Alternatively, the bonding material layers can be formed in each of the second LED stacks 33 and the second color filter 47, and the bonding material layers are bonded to each other to connect the third stack of LED 43 to the second stack of LED 33. Meanwhile, the third substrate 41 can be separated from the second stack of LED 43 using laser lifting or chemical lifting or other techniques. As such, the n-type semiconductor layer of the third LED stack 43 is exposed. The semiconductor layer of the exposed type can be subjected to surface texturing by chemical etching or the like.
[0207] [0207] Referring to FIGS. 15A and 15B, the third battery of LED 43 is standardized to expose the third transparent electrode 45,
[0208] [0208] Referring to FIGS. 16A and 16B, an insulating layer 77 covering the sides of the exposed openings is formed. The insulation layer 77 exposes the third transparent electrode 45 and also exposes the second connector 1 69d and the second connector 3 69c.
[0209] [0209] A third connector 1 79d and a third connector 2 79c are formed in the openings. The third connector 1 79d electrically connects the third transparent electrode 45 and the second connector 1 69d to each other and is isolated from the top surface of the third LED stack 43 by insulating layer 77. The third connector 2 79c is connected to the top surface of the third battery of LED 43 and the second connector 3 69c. The third connector 2 79c is electrically connected to the electrode pad 53c through the second connector 3 69c and the first connector 4 59c. The third connector 2 79c is isolated from the bottom surface of the second LED stack 43 and the third transparent electrode 45 by the insulation layer 77.
[0210] [0210] According to an exemplary embodiment, a unit pixel having anodes from the first to the third LED batteries 23, 33 and 43 common and electrically connected to each other and their cathodes connected independently can be supplied.
[0211] [0211] Although a method of making a unitary pixel has been described above according to an exemplary embodiment, a display device may include a plurality of unitary pixels arranged on substrate 51 in a matrix form. The pixels of the unit are far apart. In this case, the regions from the first to the third LED stacks 23, 33 and 43, each corresponding to the unit pixels, can be isolated in advance from each other on substrates 21, 31 and 41. Alternatively, when each of the LED stacks 23 , 33 and 43 is standardized after being connected to substrate 51, the regions of the LED cells can be isolated in regions corresponding to each pixel region. Therefore, a display device with a plurality of unitary pixels on the substrate 51 according to an exemplary embodiment can avoid the need to mount pixels individually with a small size.
[0212] [0212] In addition, in order to prevent light interference between pixels, a light reflective layer or a layer of light blocking material that covers the sides of the pixels can be added. Examples of the light reflective layer may include a distributed Bragg reflector or an insulation layer formed from SiO2 with a reflective metal layer or a highly reflective organic layer deposited on the insulating layer. As the light blocking layer, for example, black epoxy can be used. Light-blocking materials prevent light interference between light-emitting elements to increase the contrast ratio of an image.
[0213] [0213] FIG. 17 is a schematic plan view of a display device according to another exemplary embodiment. FIG. 18 is a schematic cross-sectional view taken along a line B-B of FIG. 17.
[0214] [0214] Referring to FIGS. 17 and 18, the display device according to an exemplary embodiment is generally similar to the display device described with reference to FIGS. 1 and 2, except that the cathodes from the first to the third LED batteries 23, 33 and 43 are commonly and electrically connected to each other, and their anodes are connected individually.
[0215] [0215] In particular, a first connector 1 159d electrically connects the first reflective electrode 25 to an electrode pad 153d. A second connector 1 169a electrically connects the second transparent electrode 35 to an electrode pad 153a and a third connector 1 179b electrically connects the third transparent electrode 45 to an electrode pad 153b.
[0216] [0216] In addition, a first connector 2 159c is connected to the top surface of the first LED stack 23 and to an electrode pad 153c. A second connector 2 169c is connected to the top surface of the second stack of LED 33 and to the first connector 2 159c. A third connector 2 179c is connected to the top surface of the third LED stack 43 and the second connector 2 169c. As shown in the drawings, the first 2, second 2 and third 2 connectors 159c, 169c and 179c can be stacked in the vertical direction. In addition, the third connector 2 179c can be connected to the electrode pad 153b through intermediate connectors 169b and 159b, and connectors 159b, 169b and 179b can also be stacked in the vertical direction.
[0217] [0217] FIG. 19 is a schematic circuit diagram of a display device according to an exemplary embodiment.
[0218] [0218] Referring to FIG. 19, a drive circuit according to an exemplary embodiment includes two or more transistors Tr1 and Tr2 and capacitors. When power is connected to select lines Vrow1 to Vrow3 and a data voltage is applied to data lines Vdata1 to Vdata3, a voltage is applied to the corresponding LED. The charges are charged to the corresponding capacitor according to the values from Vdata1 to Vdata3. As the activation state of Tr2 is maintained by the charged voltage of the capacitor, a voltage of the capacitor can be maintained even if the power is turned off, and a voltage can be applied to the light emitting diodes LED1 to LED3. In addition, a current flowing from LED1 to LED3 can be changed depending on the values from Vdata1 to Vdata3. A current can be constantly supplied by Vdd and, therefore, continuous light emission is possible.
[0219] [0219] Transistors Tr1 and Tr2 and capacitors can be formed on a substrate of 51. Here, LED1 to LED3 correspond to the first to third LED batteries 23, 33 and 43, respectively, which are stacked as one pixel. The anodes from the first to the third LED cells are connected to transistor Tr2 and their cathodes are grounded. According to an exemplary embodiment, the first to the third LED batteries 23, 33 and 43 can be commonly connected to each other to be grounded.
[0220] [0220] Although FIG. 19 show a circuit diagram to drive an active matrix according to an exemplary modality, however, the inventive concepts are not limited to these and another circuit can be used. In addition, while each of the anodes from LED1 to LED3 is described as connected to different Tr2 transistors and their cathodes are described as grounded, the anodes from the first to the third LED batteries 23, 33 and 43 can be connected to the common and each one of its cathodes can be connected to different transistors in some exemplary modalities.
[0221] [0221] FIG. 20 is a schematic plan view of a display device according to an exemplary embodiment.
[0222] [0222] Referring to FIG. 20, the display device includes a circuit board 201 and a plurality of light-emitting devices 200.
[0223] [0223] Circuit board 201 may include a circuit for passively driving the matrix or active driving the matrix. In an exemplary embodiment, circuit board 201 may include wires and resistors disposed on it. In another exemplary embodiment, circuit board 201 may include wires, transistors and capacitors. The circuit board 201 can also have pads on the top side of it, so that the circuit arranged on it can be electrically connected.
[0224] [0224] A plurality of light-emitting devices 200 are arranged on circuit board 201. Each light-emitting device 200 constitutes a pixel. The light emitting device 200 has electrode pads 281a, 281b, 281c and 281d and the electrode pads 281a, 281b, 281c and 281d are electrically connected to circuit board 201. The light emitting device 200 can also include a substrate 241 on the top surface. As the light-emitting devices 200 are spaced apart, the substrates 241 disposed on the upper surfaces of the light-emitting devices 200 are also spaced apart from each other.
[0225] [0225] The specific configuration of the light emitting device 200 will be described in detail with reference to FIGS. 21A and 21B. FIG. 21A is a schematic plan view of the light emitting device 200 according to an exemplary embodiment, and FIG. 21B is a cross-sectional view taken along a line A-A 'of FIG. 21A. Although the electrode pads 281a, 281b, 281c and 281d are shown as arranged on the upper side, however, the inventive concepts are not limited to these, and the light emitting device 200 can be connected to circuit board 201 of FIG. 20 and, in this case, the electrode pads 281a, 281b, 281c and 281d will be arranged on the bottom side.
[0226] [0226] Referring to FIGS. 21A and 21B, the light emitting device 200 includes substrate 241, electrode pads 281a, 281b, 281c and 281d, a first LED stack 223, a second LED stack 233, a third LED stack 243, a layer insulation 271, a first reflective electrode 228, a second transparent electrode 235, a third transparent electrode 245, first ohmic electrodes 228, a first color filter 247, a second color filter 267, a first connection layer 249, a second connection layer 269 and an upper insulation layer 273.
[0227] [0227] Substrate 241 can support LED cells 223, 233 and 243. In addition, substrate 241 can be a growth substrate for the growth of the third LED stack 243. For example, substrate 241 can be a substrate sapphire or a gallium nitride substrate, in particular, a standardized sapphire substrate. The first, second and third LED batteries are arranged on substrate 241 in the order of the third LED battery 243, the second LED battery 233 and the first LED battery
[0228] [0228] The first LED stack 223, the second LED stack 233 and the third LED stack 243 include a first semiconductor layer of conductivity type 223a, 233a or 243a, a second semiconductor layer of conductivity type 223b, 233b or 243b and an active layer interposed between them. In particular, the active layer can have a multiple quantum well structure.
[0229] [0229] The closer to substrate 241, the shorter the wavelength of light can be emitted from the LED stack. For example, the first stack of LED 223 can be an inorganic light emitting diode that emits red light, the second stack of LED 233 can be an inorganic light emitting diode that emits green light and the third stack of LED 243 can be a inorganic LED emitting blue light. The first LED stack 223 can include a GaInP based well layer and the second LED stack 233 and the third LED stack 243 can include a GaInN based well layer. However, the inventive concepts are not limited to these and, when the light emitting device 200 includes a micro LED, the first LED stack 223 can emit any one of red, green and blue light, and the second and third batteries of LED 233 and 243 can emit a light other than red, green and blue without adversely affecting the operation due to the small form factor of a micro LED.
[0230] [0230] The first semiconductor layers of conductivity type 223a, 233a and 243a of the respective LED cells 223, 233 and 243 can be semiconductor layers of type n and the second semiconductor layers of conductivity type 223b, 233b and 243b of the respective LED cells 223 , 233 and 243 can be p-type semiconductor layers. The top surface of the first LED stack 223 can be a semiconductor layer of type p 223b, the top surface of the second LED stack 233 can be a semiconductor layer of type n 233a and the top surface of the third LED stack 243 can be a semiconductor layer type p 243b. More particularly, according to an exemplary embodiment, the order of the semiconductor layers is reversed only in the second LED stack 233. The first LED stack 223 and the third LED stack 243 can have the first semiconductor layers of conductivity type 223a and 243a with textured surfaces to improve the efficiency of light extraction. The second LED stack 233 may also have the first conductivity type semiconductor layer 233a with a textured surface, however, since the first conductivity type semiconductor layer 233a is disposed further from the substrate 241 than the second layer conductivity type 233b semiconductor, surface texturing may be less effective. More particularly, when the second 233 LED battery emits green light, green light has greater visibility than red or blue light. Therefore, it may be preferable to increase the luminous efficiency of the first 223 LED battery and the third 243 LED battery more than the luminous efficiency of the second LED battery
[0231] [0231] In the first LED stack 223 and the third LED stack 243, the second semiconductor layers of conductivity type 223b and 243b can be arranged in partial regions of the first semiconductor layer of conductivity type 223a and 243a and thus the first semiconductor layers of conductivity type 223a and 243a are partially exposed. Alternatively, in the case of the second LED stack 233, the first semiconductor layer of conductivity type 233a and the second semiconductor layer of conductivity type 233b can be completely overlapped.
[0232] [0232] The first 223 LED stack is arranged in addition to the substrate 241, the second 233 LED stack is located below the first 223 LED stack and the third 243 LED stack is located below the second 233 LED stack. The first LED battery 223 can emit light with a wavelength greater than the second and third LED batteries 233 and 243, so that the light generated in the first LED battery 223 is emitted to the outside through the second and third batteries of LED 233 and 243 and substrate 241. In addition, the second 233 LED stack can emit light with a wavelength longer than the third 243 LED stack, so that the light generated in the second 233 LED stack is emitted to the through the third LED stack 243 and the substrate 241. However, the inventive concepts are not limited to these. For example, when the light emitting device 200 includes a micro LED, the first LED battery 223 can emit any red, green and blue light, and the second and third LED batteries 233 and 243 can emit a light other than red, green and blue without adversely affecting the operation due to the small form factor of a micro LED
[0233] [0233] The insulation layer 271 is arranged in the first LED stack 223 and has an opening to expose the second conductivity type semiconductor layer 223b of the first LED stack 223. The insulation layer 271 can have, for example, a opening having substantially an annular shape. The insulation layer 271 can be a transparent insulation layer with a lower refractive index than the first LED stack 223.
[0234] [0234] The first reflector electrode 228 is in ohmic contact with the second conductivity semiconductor layer 223b of the first LED stack 223 and reflects the light generated in the first LED stack 223 towards substrate 241. The first reflective electrode 228 is arranged in insulation layer 271 and is connected to the first LED stack 223 through the opening of insulation layer 271.
[0235] [0235] The first reflective electrode 228 may include an ohmic contact layer 228a and a reflective layer 228b. The ohmic contact layer 228a is in partial contact with the second semiconductor layer of conductivity type 223b, for example, a semiconductor layer of type p. The ohmic contact layer 228a can be formed in a predetermined area to prevent the ohmic contact layer 226a from absorbing light. The ohmic contact layer 228a can be formed in the second semiconductor layer of conductivity type 223b exposed in the openings of the insulation layer 271. The ohmic contact layer 228a can be formed to be substantially annular in shape. The ohmic contact layer 228a can be formed by a transparent conductive oxide, for example, Au alloy such as Au (Zn) or Au (Be).
[0236] [0236] The reflective layer 228b covers the ohmic contact layer 228a and the insulating layer 271. When the reflective layer 228b covers the insulating layer 271, the first LED stack 223 may have a stacked structure of the first LED stack 223 having a relatively low refractive index and insulation layer 271 having a relatively low refractive index and reflective layer 228b, which can form an omnidirectional reflector. The reflective layer 228b can include a reflective metal layer, such as Al, Ag or Au. In addition, reflective layer 228b can include an adhesive metal layer, such as Ti, Ta, Ni or Cr on the upper and lower surfaces of the reflective metal layer to improve adhesion of the reflective metal layer. Au is particularly suitable for the reflective layer 228b formed in the first LED stack 223 because its high reflectance for red light and low reflectance for blue light or green light. The reflective layer 228b can cover more than 50% in the area of the first 223 LED stack and can cover most of the area to improve light efficiency.
[0237] [0237] The ohmic contact layer 228a and the reflective layer 228b can be formed by a metal layer containing Au. The reflective layer 228b can be formed by a metal layer with high reflectance of light generated in the first LED stack 223, for example, red light. The reflective layer 228b can have a relatively low reflectance of the light generated in the second LED battery 233 and the third LED battery 243, for example, green light or blue light and, consequently, light generated in the second and third LED batteries 233 and 243 and the incident in the reflective layer 228b can be absorbed to reduce optical interference.
[0238] [0238] A first ohmic electrode 226 is disposed in the first semiconductor layer of the conductivity type 223a exposed and is in ohmic contact with the first semiconductor layer of the conductivity type 223a. The first ohmic electrode 226 can also be formed from a metal layer containing Au.
[0239] [0239] The second transparent electrode 235 is in ohmic contact with the second semiconductor layer of conductivity type 233b of the second LED stack 233. As shown in the drawing, the second transparent electrode 235 is in contact with a lower surface of the second battery of LED 233 between the second battery of LED 233 and the third battery of LED 243. The second transparent electrode 235 can be formed by a metal layer or a layer of conductive oxide that is transparent to red light and green light.
[0240] [0240] In addition, the third transparent electrode 245 is in ohmic contact with the second semiconductor layer of conductivity type 243b of the third LED stack 243. The third transparent electrode 245 can be arranged between the second LED stack 233 and the third LED battery 243 and is in contact with an upper surface of the third LED battery 243. The third transparent electrode 245 can be formed by a metal layer or a conductive oxide layer that is transparent to red light and green light. The third transparent electrode 245 can also be transparent to blue light according to some exemplary modalities. The second transparent electrode 235 and the third transparent electrode 245 can assist the distribution of current by ohmic contact with the p-type semiconductor layer of each LED cell. Examples of the conductive oxide layer used for the second and third transparent electrodes 235 and 245 include SnO2, InO2, ITO, ZnO, IZO, or others.
[0241] [0241] The first color filter 247 can be disposed between the third transparent electrode 245 and the second battery of LED 233 and the second color filter 267 can be disposed between the second battery of LED 233 and the first battery of LED 223. The first color filter 247 can transmit light generated in the first and second LED batteries 223 and 233 and reflect the light generated in the third LED stack 243. The second color filter 267 can transmit light generated in the first LED stack 223 and reflect the light generated in the second LED battery 233. Therefore, the light generated in the first LED battery 223 can be emitted to the outside through the second LED battery 233 and the third LED battery 243, and the light generated in the second battery of LED 233 can be emitted to the outside via the third battery of LED 243. In addition, the light generated in the second battery of LED 233 can be prevented from being lost by being incident on the first battery of LED 223, or the light generated in the third LED stack 243 can be prevented to be lost due to incident on the second 233 LED battery.
[0242] [0242] In some exemplary embodiments, the second color filter 267 can reflect the light generated in the third LED stack 243.
[0243] [0243] * 242 The first and second color filters 247 and 267 can be, for example, a low frequency band, such as a low pass filter that passes only a long wavelength band, a low pass filter band that passes only a predetermined wavelength band or a band interrupt filter that blocks only a predetermined wavelength band. In particular, the first and second color filters 247 and 267 can be formed by the alternating stacking of insulation layers with different refractive indices, for example, they can be formed by the alternating stacking of the TiO2 insulation layer and the insulation layer of SiO2. In particular, the first and second color filters 247 and 267 may include a distributed Bragg reflector (DBR). The interruption band of the reflector
[0244] [0244] The first connection layer 249 couples the second battery of LED 233 to the third battery of LED 243. The first connection layer 249 covers the first color filter 247 and is connected to the second transparent electrode 235. For example, the first bonding layer 249 can be a transparent organic layer or a transparent inorganic layer. Examples of the organic layer include SU8, poly (methylmethacrylate) (PMMA), polyimide, parylene and benzocyclobutene (BCB), examples of the inorganic layer include Al2O3, SiO2, SiNx or others. The organic layers can be connected to a high vacuum and a high pressure, and the inorganic layers can be connected to a high vacuum, in a state where the surface energy is reduced using plasma or the like, after flattening the surface by a product mechanical chemical polishing process, for example.
[0245] [0245] The second layer of connection 269 couples the second battery of LED 233 to the first battery of LED 223. As shown in the drawing, the second layer of connection 269 can cover the second color filter 267 and be in contact with the first battery LED
[0246] [0246] The upper insulation layer 273 covers the side surfaces and the upper parts of the first, second and third LED batteries 223, 233 and 243. The upper insulation layer 273 can be formed by SiO2, Si3N4, SOG or others. Alternatively, the upper insulating layer 273 may contain a light-reflecting material or a light-blocking material to prevent optical interference in the adjacent light-emitting device. For example, the top insulating layer 273 can include a distributed Bragg reflector that reflects red light, green light and blue light, or a SiO2 layer with a reflective metal layer or a highly reflective organic layer deposited on it. Alternatively, the top insulating layer 273 may contain a black epoxy, as a light blocking material, for example. The light-blocking material increases the contrast of an image, preventing optical interference between light-emitting devices.
[0247] [0247] The top insulating layer 273 has openings to expose the first ohmic electrode 26, the first reflective electrode 228, the second and third transparent electrodes 235 and 245 and the second and third LED batteries 233 and 243. The holes can be formed to pass through the first LED stack 223 and the second LED stack 233, and the top insulating layer 273 can cover the side walls of the holes while exposing the bottom surface of the holes.
[0248] [0248] The electrode pads 281a, 281b, 281c and 281d are arranged above the first LED battery 223 and are electrically connected to the first, second and third LED batteries 223, 233 and 243. The electrode pads 281a, 281b, 281c and 281d can be arranged in the upper insulation layer 273 and connected to the first ohmic electrode 26, the first reflective electrode 228, the second and third transparent electrodes 235 and 245 and the second and third LED batteries 233 and 243, which are exposed through holes h1, h2, h3, h4 and h5.
[0249] [0249] For example, the first electrode pad 281a can be connected to the first ohmic electrode 26 through hole h4 that passes through the upper insulation layer 273. The first electrode pad 281a is electrically connected to the first type semiconductor layer. conductivity 223a of the first LED stack 223.
[0250] [0250] The second electrode pad 281b can be connected to the first conductivity type semiconductor layer 233a of the second LED stack 233 through hole h3 that passes through the top insulation layer 273 and the first LED stack 223.
[0251] [0251] The third electrode pad 281c can be electrically connected to the first conductivity type semiconductor layer 243a of the third LED stack 243 through hole h2 that passes through the top insulating layer 273, the first LED stack 223 and the second LED stack 233. Hole h2 can pass through the second semiconductor layer of conductivity type 243b of the third LED stack 243 and the active layer.
[0252] [0252] Meanwhile, the common electrode pad 281d can be connected in common to the first reflective electrode 228, the second transparent electrode 235 and the third transparent electrode 245 through holes h1 and h5. Hole h1 passes through the first battery of LED 223 and the second battery of LED 233 to expose the second transparent electrode 235 and the third transparent electrode 245, and the hole h5 exposes the first reflective electrode 228. Therefore, the electrode pad common 281d is electrically connected in common to the second semiconductor layer of conductivity type 223b of the first LED stack 223, the second semiconductor layer of conductivity type 233b of the second LED stack 233 and the second semiconductor layer of conductivity type 243b of the third LED stack 243. In addition, as shown in FIG. 21B, the common electrode pad 281d can be connected to the third LED stack 243 through hole h1 that passes through a hollow portion surrounded by the first reflective electrode 228.
[0253] [0253] According to an exemplary embodiment, the first LED battery 223 is electrically connected to the electrode pads 281d and 281a, the second LED battery 233 is electrically connected to the electrode pads 281d and 281b and the third LED battery 243 is electrically connected to the electrode pads 281d and 281c. Therefore, the anodes of the first LED battery 223, the second LED battery 233 and the third LED battery 243 are electrically connected in common to the electrode pad 281d, and their cathodes are electrically connected to the first, second and third pads electrodes 281a, 281b and 281c, respectively. Thus, the first, second and third LED batteries 223, 233 and 243 can be activated independently.
[0254] [0254] FIGS. 22, 23, 24, 25, 26A, 26B, 27A, 27B, 28A, 28B, 29, 30A, 30B, 31A, 31B, 32A, 32B, 33A, 33B, 34A, 34B, 35A and 35B are schematic views and cross-sectional views illustrating a method of manufacturing the light-emitting device 200 according to an exemplary embodiment. In the drawings, each plan view corresponds to a plan view of FIG. 21A and each cross-sectional view is taken along a line A-A of FIG. 21A.
[0255] [0255] First, with reference to FIG. 22, the first LED stack 223 is grown on a first substrate 221. The first substrate 221 can be a GaAs substrate, for example. The first LED stack 223 is formed by semiconductor layers based on AlGaInP and includes the first semiconductor layer of conductivity type 223a, the active layer and the second semiconductor layer of conductivity type 223b. Here, the first type of conductivity can be type n and the second type of conductivity can be type p.
[0256] [0256] Referring to FIG. 23, the second LED stack 233 is grown on a second substrate 231 and the second transparent electrode 235 is formed on the second LED stack 233. The second LED stack 233 is formed by semiconductor layers based on gallium nitride and may include the first semiconductor layer of conductivity type 233a, the active layer and the second semiconductor layer of conductivity type 233b. The active layer can include a GaInN well layer. Here, the first type of conductivity can be type n and the second type of conductivity can be type p.
[0257] [0257] The second substrate 231 is a substrate on which a semiconductor layer based on gallium nitride can be grown and is different from the first substrate 221. The composition ratio of the GaInN well layer can be determined so that the second pile LED light emits green light, for example. The second transparent electrode 235 is in ohmic contact with the second semiconductor layer of conductivity type 233b. The second transparent electrode 235 can be formed from a conductive oxide layer, such as SnO2, InO2, ITO, ZnO or IZO.
[0258] [0258] Referring to FIG. 24, the third LED stack 243 is grown on a third substrate 241 and the third transparent electrode 245 and the first color filter 247 are formed on the third LED stack 243. The third LED stack 243 is formed by semiconductor layers based on gallium nitride and includes the first semiconductor layer of conductivity type 243a, the active layer and the second semiconductor layer of conductivity type 243b. The active layer can also include a GaInN well layer. Here, the first type of conductivity can be type n and the second type of conductivity can be type p.
[0259] [0259] The third substrate 241 is a substrate on which a semiconductor layer based on gallium nitride can be grown and is different from the first substrate 221. The composition ratio of the GaInN well layer can be determined so that the third pile LED light emits blue light, for example. The third transparent electrode 245 is in ohmic contact with the second semiconductor layer of conductivity type 243b. The third transparent electrode 245 can be formed from a conductive oxide layer, such as SnO2, InO2, ITO, ZnO or IZO.
[0260] [0260] Since the first color filter 247 is substantially the same as that described with reference to FIGS. 21A and 21B, their detailed descriptions will be omitted to avoid redundancy.
[0261] [0261] Referring to FIG. 25, the second LED stack 233 of FIG. 223 is connected to the third LED stack 243 of FIG. 24.
[0262] [0262] The first color filter 247 and the second transparent electrode 235 are connected so as to face each other. For example, layers of bonding material are formed in the first color filter 247 and the second transparent electrode 235, respectively, and by connecting the first color filter 247 and the second transparent electrode 235, the first connection layer 249 can be formed. The layers of the bonding material can be, for example, a transparent organic layer or a transparent inorganic layer. Examples of the organic layer include SU8, poly (methylmethacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB) or others, and examples of the inorganic layer include Al2O3, SiO2, SiNx or others. The organic layers can be connected to a high vacuum and a high pressure, and the inorganic layers can be connected to a high vacuum, in a state where the surface energy is reduced using plasma or the like, after flattening the surface by a product mechanical chemical polishing process, for example.
[0263] [0263] Then, the second substrate 231 is removed from the second stack of LED 233, using techniques such as laser lifting or chemical lifting. Therefore, the first conductivity type semiconductor layer 233a of the second LED stack 233 is exposed from above. The surface of the exposed conductivity type first semiconductor layer 233a can be textured.
[0264] [0264] Meanwhile, before coupling the first 223 LED stack to the second LED stack, a reflective electrode and an ohmic electrode are formed first on the first 223 LED stack and substrate 221 is removed using a carrier substrate. This will be described in more detail below with reference to FIGS. 26A, 26B, 27A, 27B, 28A, 28B and 29.
[0265] [0265] Referring to FIGS. 26A and 26B, the second conductivity type semiconductor layer 223b of the first LED stack 223 of FIG. 22 is standardized to expose the first conductivity type semiconductor layer 223a. A region of the light emitting device can be substantially rectangular in shape, as shown in FIG. 26A. Here, the second semiconductor layer of conductivity type 223b is removed in the vicinity of four corners in a region of light emitting device. As shown in Fig. 26A, the entire second conductivity type semiconductor layer 223b can be removed in the vicinity of three corners and a hole passing through the second conductivity type semiconductor layer 223b can be formed in the vicinity of a corner. Here, although a region of the light-emitting device is shown, a plurality of regions of the light-emitting device can be provided on substrate 241, and the second semiconductor layer of conductivity type 223b can be standardized in each region of the light-emitting device. according to some exemplary modalities.
[0266] [0266] Referring to FIGS. 27A and 27B, the first ohmic electrode 226 is formed in the vicinity of a corner. The first ohmic electrode 26 is in ohmic contact with the first semiconductor layer of conductivity type 223a.
[0267] [0267] Next, the insulation layer 271 covering the first ohmic electrode 226 and the first LED stack 223 is formed and standardized to form an opening to expose the second conductivity-like semiconductor layer 223b. For example, SiO2 is formed in the first 223 LED stack, a photoresistor is applied to it, and then a photoresistor pattern is formed using photolithography and development. Then, SiO2 is standardized using the photoresistor pattern as an etching mask to form insulation layer 271 that has an opening.
[0268] [0268] The opening can be formed around the hole that passes through the second semiconductor layer of conductivity type 223b and can surround the hole having a substantially annular shape.
[0269] [0269] Then, the ohmic contact layer 228a is formed at the opening of the insulation layer 271. The ohmic contact layer 228a can be formed using a lifting technique or the like. The ohmic contact layer 228a can be formed to have substantially an annular shape along the shape of the opening.
[0270] [0270] Referring to FIGS. 28A and 28B, after the ohmic contact layer 228a is formed, the reflective layer 228b that covers the ohmic contact layer 228a and the insulating layer 271 is formed. The reflective layer 228b can be formed using a lifting technique or the like. The first reflective electrode 228 is formed by the ohmic contact layer 228a and the reflective layer 228b.
[0271] [0271] The first reflective electrode 228 may have a shape in which four corner portions are removed in a rectangular region of the light-emitting device, as shown in the drawing. In particular, in a corner portion, the first reflective electrode 228 may have a hollow portion above a hole formed in the second conductivity type semiconductor layer 223b. Here, although a region of the light-emitting device is shown, a plurality of regions of the light-emitting device can be provided on the substrate 221, and the first reflecting electrode 228 can be formed in each region of the light-emitting device according to some exemplary modalities.
[0272] [0272] Referring to FIG. 29, the carrier substrate 251 is connected to the first LED stack 223 of FIGS. 28A and 28B. The first reflective electrode 228 is arranged to face the carrier substrate 251 and the first LED stack 223 can be attached to the carrier substrate 251 using adhesive layer 253. Then, substrate 221 is removed from the first LED stack 223. Therefore, the first semiconductor layer of conductivity type 223a is exposed. The surface of the first semiconductor layer 223a of the exposed conductivity type can be textured to improve the efficiency of light extraction, so that a rough surface or light extraction structure can be formed on the surface of the first semiconductor layer 223a of the conductivity type .
[0273] [0273] Next, with reference to FIG. 25, a method of manufacturing the light-emitting device 200 by connecting the first LED battery 223 to the second LED battery 233 will be described.
[0274] [0274] Referring to FIGS. 30A and 30B, first, the second color filter 267 is formed on the exposed first semiconductor layer 233a of conductivity type of the second LED stack 233 of FIG. 25. Since the second color filter 267 is substantially the same as that described with reference to FIGS. 21A and 21B, detailed descriptions will be omitted.
[0275] [0275] The first LED battery 223 is connected to the second LED battery 233. The second color filter 267 and the first LED battery 223 can be connected to each other. For example, layers of bonding material are formed in the second color filter 267 and the first LED stack 223, respectively, and by connecting the second color filter 267 and the first LED stack 223, the second bond layer 269. can be formed. The layers of the bonding material can be a transparent organic layer or a transparent inorganic layer as described above.
[0276] [0276] Then, the carrier substrate 251 and the adhesive layer 253 are removed. Therefore, the first reflective electrode 228 is exposed.
[0277] [0277] Referring to FIGS. 31A and 31B, the insulation layer 271 is patterned to expose the first LED stack 223 around the first reflector electrode 228 and then the first LED stack 223, the second link layer 269 and the second color filter 269 are sequentially patterned to form holes h1, h2 and h3 through which the first conductivity type semiconductor layer 233a of the second LED stack 233 is exposed. In addition, the second LED stack 233 is standardized so that the holes h1 and h2 pass through the second LED stack 233 to expose the second transparent electrode 235. The orifice h3 is maintained to expose the first conductivity type semiconductor layer 233a of the second 233 LED stack.
[0278] [0278] In addition, the insulation layer 271, the first LED stack 223, the second link layer 269, the second color filter 267 and the second LED stack 233 are removed sequentially so that the second transparent electrode 235 is exposed on the edge portions of the light regions of the emitting device.
[0279] [0279] Referring to FIGS. 32A and 32B, the second transparent electrode 235, the first connection layer 249 and the first color filter 247 are removed to expose the third transparent electrode 245 through the holes h1 and h2. The upper surface of the second transparent electrode 235 is partially exposed in the orifice h1.
[0280] [0280] In addition, the second transparent electrode 235, the first connection layer 249 and the first color filter 247 are also removed at the edge portions of the regions of the light emitting device to expose the third transparent electrode 245.
[0281] [0281] Referring to FIGS. 33A and 33B, the third transparent electrode 245 and the second semiconductor layer of conductivity type 243b are standardized to expose the first conductivity type semiconductor layer 243a of the third LED stack 243 through hole h2. The orifice h1 is maintained to expose the third transparent electrode 245.
[0282] [0282] In addition, the third transparent electrode 245 and the third LED stack 243 are removed so that the substrate 241 is exposed at the edge portions of the regions of the light emitting device. The exposed regions of substrate 241 can be diced regions to divide the light emitting devices.
[0283] [0283] As shown in Fig. 33B, hole h1 is formed to pass through the hollow portion of the first reflective electrode 228 and exposes the second transparent electrode 235 and the second transparent electrode 245. Orifice h2 passes through the first and second LED batteries 223 and 233 and exposes the first conductivity type semiconductor layer 243a passing through the second conductivity type semiconductor layer 243b. Hole h3 passes through the first LED stack 223 and exposes the first conductivity type semiconductor layer 233a of the second LED stack 233.
[0284] [0284] Referring to FIGS. 34A and 34B, the top insulation layer 273 is formed to cover the side surfaces and an upper region of the first, second and third LED cells 223, 233 and 243. The top insulation layer 273 can be formed of a single layer or multiple layers of SiO2, Si3N4, SOG or others. Alternatively, the upper insulating layer 273 may contain a light-reflecting material or a light-blocking material to prevent optical interference between adjacent light-emitting devices. For example, the top insulating layer 273 can include a distributed Bragg reflector that reflects red light, green light and blue light, or a SiO2 layer with a reflective metal layer or a highly reflective organic layer deposited on it. Alternatively, the top insulating layer 273 may contain a black epoxy, as a light blocking material, for example. Light-blocking material can increase the contrast of an image, preventing optical interference between light-emitting devices. The distributed Bragg reflector can be formed, for example, by depositing layers of SiO2 and TiO2 alternately.
[0285] [0285] Then, the top insulation layer 273 is standardized using photolithography and engraving techniques to form openings in holes h1, h2 and h3, and openings h4 and h5 are formed. The upper insulating layer 273 exposes the second transparent electrode 235 and the third transparent electrode 245 in hole h1 and covers the sides of the first LED stack 223 and the second LED stack 233. In addition, the upper insulating layer 273 covers the sidewall in hole h2 while exposing the first conductivity type semiconductor layer 243a. In addition, the upper insulation layer 273 exposes the first conductivity type semiconductor layer 233a of the second LED stack 233 in the orifice h3. Meanwhile, hole h4 passes through the upper insulation layer 273 and insulation layer 271 to expose the first ohmic electrode 226, and hole h5 passes through the upper insulation layer 273 to expose the first reflective electrode 228. The hole h5 can be formed to be substantially annular in shape, as shown in FIG. 34A.
[0286] [0286] Referring to FIGS. 35A and 35B, electrode pads 281a, 281b, 281c and 281d are formed in the upper insulating layer 273. Electrode pads 281a, 281b, 281c and 281d include the first electrode pad 281a, the second electrode pad 281b, the third electrode pad 281c and the common electrode pad 281d.
[0287] [0287] The common electrode pad 281d is connected to the second transparent electrode 235 and the second transparent electrode 245 through hole h1 and to the first reflective electrode 228 through hole h5. Thus, the common electrode pad 281d is electrically connected in common to the anodes of the first, second and third LED batteries 223, 233 and 243.
[0288] [0288] The first electrode pad 281a is connected to the first ohmic electrode 226 through hole h4 and electrically connected to the cathode of the first LED stack 223, for example, the first semiconductor layer of conductivity type 223a. Meanwhile, the second electrode pad 281b is electrically connected to the cathode of the second LED stack 233, for example, the first semiconductor layer of conductivity type 233a through hole h3, and the third electrode pad 281c is electrically connected to the cathode of the third LED stack 243, for example, the first conductivity type semiconductor layer 243a through hole h2.
[0289] [0289] Meanwhile, the electrode pads 281a, 281b, 281c and 281d are electrically separated from each other, so that each of the first, second and third LED batteries 223, 233 and 243 are electrically connected to two electrode pads. electrodes and is adapted to be activated independently.
[0290] [0290] Subsequently, the light-emitting device 200, according to an exemplary embodiment, is provided by dividing the substrate 241 into regions of the light-emitting device. As shown in Fig. 35A, electrode pads 281a, 281b, 281c and 281d can be arranged in four corners of each light emitting device 200. In addition, electrode pads 281a, 281b, 281c and 281d can be shaped substantially rectangular, but are not limited to these.
[0291] [0291] Although substrate 241 is described above as divided, according to some exemplary embodiments, substrate 241 can be removed so that the surface of the first semiconductor layer 243 of exposed conductivity can be textured. The substrate 241 can be removed after connecting the first battery of LED 223 to the second battery of LED 233, or it can be removed after the formation of the electrode pads 281a, 281b, 281c and 281d.
[0292] [0292] According to the exemplary modalities, a light-emitting device includes anodes from the first, second and third LED batteries 223, 233 and 243 that are electrically connected in common and their cathodes are connected independently. However, the inventive concepts are limited to these and, for example, the anodes of the first, second and third LED batteries 223, 233 and 243 can be connected independently to the electrodes, and the cathodes can be electrically connected in common.
[0293] [0293] The light emitting device 200 can include the first, second and third LED batteries 223, 233 and 243 to emit red, green and blue light and therefore can be used as a single pixel on a display device. As described with reference to FIG. 20, a display device can be provided by aligning a plurality of light emitting devices 200 on circuit board 201. Since the light emitting device 200 includes the first, second and third LED batteries 223, 233 and 243 , the subpixel area in a pixel can be increased. In addition, the first, second and third LED batteries 223, 233 and 243 can be assembled by mounting a light emitting device 200, thereby reducing the number of assembly processes.
[0294] [0294] As described with reference to FIG. 20, the light-emitting devices 200 mounted on the circuit board 201 can be driven by a passive matrix method or an active matrix method.
[0295] [0295] FIG. 36 is a schematic cross-sectional view of a stack of LEDs for a display according to an exemplary embodiment.
[0296] [0296] Referring to FIG. 36, the light emitting diode stack 1000 includes a support substrate 1510, a first stack of LED 1230, a second stack of LED 1330, a third stack of LED 1430, a reflective electrode 1250, an ohmic electrode 1290, a second transparent electrode 1350, a third transparent electrode p 1450, an insulating layer 1270, a first color filter 1370, a second color filter 1470, a first connection layer 1530, a second connection layer 1550 and a third connection layer 1570. In addition, the first 1230 LED battery can include an ohmic contact portion 1230a for ohmic contact.
[0297] [0297] The support substrate 1510 supports the semiconductor cells 1230, 1330 and 1430. The support substrate 1510 may include a circuit on a surface of the same or in it, but the inventive concepts are not limited to it. The support substrate 1510 can include, for example, a Si substrate or a Ge substrate.
[0298] [0298] Each of the first 1230 LED stack, the second 1330 LED stack and the 1430 LED stack includes a n-type semiconductor layer, a p-type semiconductor layer and an active layer interposed between them. The active layer can have a multi-quantum well structure.
[0299] [0299] For example, the first 1230 LED battery can be an inorganic light emitting diode configured to emit red light, the second 1330 LED battery can be an inorganic light emitting diode configured to emit green light and the third battery of LED 1430 can be an inorganic light emitting diode configured to emit blue light. The first 1230 LED stack can include a GaInP based well layer, and each of the second 1330 LED stack and the third 1430 LED stack can include a GaInN based well layer.
[0300] [0300] Furthermore, both surfaces of each of the first to third LED batteries 1230, 1330, 1430 are a type n semiconductor layer and a type p semiconductor layer, respectively. In the exemplary embodiment illustrated, each of the first to third LED batteries 1230, 1330 and 1430 has an upper surface of type n and a lower surface of type p. Since the third battery of LED 1430 has an upper surface of type n, a rough surface can be formed on the upper surface of the third battery of LED 1430 through chemical engraving. However, the inventive concepts are not limited to them, and the types of semiconductors on the top and bottom surfaces of each of the LED cells can be arranged alternatively.
[0301] [0301] The first 1230 LED stack is arranged close to the supporting substrate 1510, the second 1330 LED stack is placed on the first 1230 LED stack and the third 1430 LED stack is placed on the second 1330 LED stack. Once Since the first 1230 LED battery emits light with a longer wavelength than the second and third 1330 and 1430 LED batteries, the light generated from the first 1230 LED battery can be emitted externally through the second and third LED batteries. LEDs 1330 and 1430. In addition, since the second battery of 1330 LED emits light with a wavelength greater than the third battery of LED 1430, the light generated from the second battery of LED 1330 can be emitted out through of the third 1430 LED stack.
[0302] [0302] The reflective electrode 1250 forms ohmic contact with the p-type semiconductor layer of the first 1230 LED cell and reflects the light generated from the first 1230 LED cell. For example, the reflective electrode 1250 may include a contact layer ohmic 1250a and a reflective layer 1250b.
[0303] [0303] The ohmic contact layer 1250a partially contacts the p-type semiconductor layer of the first 1230 LED stack. To prevent light absorption by the ohmic contact layer 1250a, a region in which the ohmic contact layer 1250a comes into contact. Contact with the p-type semiconductor layer may not exceed 50% of the total area of the p-type semiconductor layer. The reflective layer 1250b covers the ohmic contact layer 1250a and the insulating layer 1270. As shown in Fig. 36, the reflective layer 1250b can cover substantially the entire ohmic contact layer 1250a, without being limited thereto. Alternatively, the reflective layer 1250b can cover a portion of the ohmic contact layer 1250a.
[0304] [0304] Since the reflective layer 1250b covers the insulating layer 1270, an omnidirectional reflector can be formed by the stacked structure of the first 1230 LED stack with a relatively high refractive index, and the insulating layer 1270 and the reflecting layer 1250b with a relatively low refractive index. The reflective layer 1250b can cover 50% or more of the area of the first 1230 LED battery, or most of the first 1230 LED battery, thus improving luminous efficiency.
[0305] [0305] The ohmic contact layer 1250a and the reflective layer 1250b can be metal layers, which can include Au. The reflective layer 1250b can be formed of a metal with a relatively high reflectance in relation to the light generated from the first stack of LED 1230, for example, red light. On the other hand, the reflective layer 1250b can be formed by a metal with relatively low reflectance in relation to the light generated from the second battery of LED 1330 and the third battery of LED 1430, for example, green light or blue light, to reduce light interference having been generated from the second and third LED batteries 1330 and 1430 and traveling towards the support substrate 1510.
[0306] [0306] The insulation layer 1270 is interposed between the supporting substrate 1510 and the first 1230 LED stack and has openings that expose the first 1230 LED stack. The ohmic contact layer 1250a is connected to the first 1230 LED stack in the openings of the insulation layer 1270.
[0307] [0307] The ohmic electrode 1290 is arranged on the top surface of the first 1230 LED battery. In order to reduce the ohmic contact resistance of the ohmic electrode 1290, the ohmic contact portion 1230a may protrude from the upper surface of the first 1230 LED battery. The ohmic electrode 1290 can be arranged in the ohmic contact portion 1230a.
[0308] [0308] The second transparent p 1350 electrode forms ohmic contact with the p type semiconductor layer of the second 1330 LED stack. The second transparent p 1350 electrode can include a metal layer or a conductive oxide layer that is transparent to red light and green light.
[0309] [0309] The third transparent p 1450 electrode forms ohmic contact with the p type semiconductor layer of the third 1430 LED stack. The third transparent p 1450 electrode can include a metal layer or a conductive oxide layer that is transparent to red light , green light and blue light.
[0310] [0310] The reflective electrode 1250, the second transparent electrode p 1350 and the third transparent electrode p 1450 can assist in the propagation of current through the ohmic contact with the type p semiconductor layer of the corresponding LED stack.
[0311] [0311] The first 1370 color filter can be interposed between the first 1230 LED stack and the second 1330 LED stack. The second 1470 color filter can be interposed between the second 1330 LED stack and the third 1430 LED stack. The first 1370 color filter transmits light generated from the first 1230 LED battery while reflecting the light generated from the second 1330 LED battery. The second 1470 color filter transmits light generated from the first and second LED batteries. 1230 and 1330, while reflecting the light generated from the third battery of LED 1430. As such, the light generated from the first battery of LED 1230 can be emitted out through the second battery of LED 1330 and the third battery of LED 1430, and the light generated from the second 1330 LED battery can be emitted out through the third 1430 LED battery. In addition, the light generated from the second 1330 LED battery can be prevented from entering the first 1330 LED battery. LED 1230 and the light generated from the third battery of LED 1430 can be prevented from entering the second battery of LED 1330, thus preventing the loss of light.
[0312] [0312] In some exemplary embodiments, the first 1370 color filter can reflect the light generated from the third 1430 LED stack.
[0313] [0313] The first and second color filters 1370 and 1470 can be, for example, a low pass filter that transmits light in a low frequency band, that is, in a long wavelength band, a bandpass filter which transmits light in a predetermined wavelength range, or a band interrupt filter that prevents light in a predetermined wavelength range from passing through it. In particular, each of the first and second color filters 1370 and 1470 may include a distributed Bragg reflector (DBR). The distributed Bragg reflector can be formed by alternately stacking layers of insulation with different refractive indices one above the other, for example, TiO2 and SiO2. In addition, the interruption range of the distributed Bragg reflector can be controlled by adjusting the thicknesses of the TiO2 and SiO2 layers. The low-pass filter and the band-pass filter can also be formed by alternately stacking layers of insulation with different refractive indices one above the other.
[0314] [0314] The first link layer 1530 couples the first stack of LED 1230 to the support substrate 1510. As shown in Fig. 36, the reflective electrode 1250 can join with the first link layer 1530. The first link layer 1530 it can be a transmissive layer or opaque to light.
[0315] [0315] The second connection layer 1550 couples the second battery of LED 1330 to the first battery of LED 1230. As shown in Fig. 36, the second connection layer 1550 can join the first battery of LED 1230 and the first color filter 1370. The ohmic electrode 1290 can be covered by the second connection layer 1550. The second connection layer 1550 transmits light generated from the first 1230 LED stack. The second connection layer 1550 can be formed, for example, by spin- light transmissive on-glass.
[0316] [0316] The third layer of link 1570 couples the third stack of LED 1430 to the second stack of LED 1330. As shown in Fig. 36, the third layer of link 1570 can join the second stack of LED 1330 and the second filter of color 1470. However, the inventive concepts are not limited to these. For example, a transparent conductive layer can be arranged on the second stack of LED 1330. The third layer of link 1570 transmits light generated from the first stack of LED 1230 and the second stack of LED 1330. The third layer of link 1570 can be formed, for example, by light transmissive spin-on-glass.
[0317] [0317] FIGS. 37A, 37B, 37C, 37D and 37E are schematic cross-sectional views that illustrate a method of manufacturing a stack of light-emitting diodes for a display according to an exemplary embodiment.
[0318] [0318] Referring to FIG. 37A, a first 1230 LED stack is grown on a first substrate 1210. The first substrate 1210 can be, for example, a GaAs substrate. The first 1230 LED stack can be formed by semiconductor layers based on AlGaInP and includes a n-type semiconductor layer, an active layer and a p-type semiconductor layer.
[0319] [0319] An insulating layer 1270 is formed on the first stack of LED 1230 and is standardized to form openings. For example, a SiO2 layer is formed on the first 1230 LED stack and a photoresistor is deposited on the SiO2 layer, followed by photolithography and development to form a photoresistor pattern. Then, the SiO2 layer is standardized using the photoresistor pattern used as an attack mask, thus forming the 1270 insulation layer.
[0320] [0320] Then, an ohmic contact layer 1250a is formed in the openings of the insulation layer 1270. The ohmic contact layer 1250a can be formed by a lifting process or the like. After the formation of the ohmic contact layer 1250a, a reflective layer 1250b is formed to cover the ohmic contact layer 1250a and the insulating layer 1270. The reflective layer 1250b can be formed by a lifting process or the like. The reflective layer 1250b can cover a portion of the ohmic contact layer 1250a or all of it, as shown in FIG. 37A. The ohmic contact layer 1250a and the reflective layer 1250b form a reflective electrode 1250.
[0321] [0321] The reflective electrode 1250 forms ohmic contact with the p-type semiconductor layer of the first 1230 LED stack and, therefore, will be hereinafter referred to as a first reflective electrode p 1250.
[0322] [0322] Referring to FIG. 37B, a second stack of LED 1330 is grown on a second substrate 1310 and a second transparent electrode p 1350 and a first color filter 1370 are formed on the second stack of LED 1330. The second stack of LED 1330 can be formed by layers of semiconductors based on GaN and include a GaInN well layer. The second substrate 1310 is a substrate on which the GaN-based semiconductor layers can be grown on it and is different from the first substrate 1210. The composition ratio of GaInN to the second 1330 LED stack can be determined so that the second 1330 LED battery emit green light. The second transparent p1350 electrode forms ohmic contact with the p-type semiconductor layer of the second 1330 LED battery.
[0323] [0323] Referring to FIG. 37C, a third stack of LED 1430 is grown on a third substrate 1410, and a third transparent electrode p 1450 and a second color filter 1470 are formed on the third stack of LED 1430. The third stack of LED 1430 can be formed by layers of GaN-based semiconductors and include a GaInN well layer. The third substrate 1410 is a substrate on which the GaN-based semiconductor layers can be grown on it and is different from the first substrate 1210. The ratio of GaInN composition to the third LED stack 1430 can be determined so that the third stack LED light emits blue light. The third transparent p 1450 electrode forms ohmic contact with the p-type semiconductor layer of the third 1430 LED battery.
[0324] [0324] The first color filter 1370 and the second color filter 1470 are substantially the same as those described with reference to FIG. 36 and, therefore, repeated descriptions will be omitted to avoid redundancy.
[0325] [0325] As such, the first stack of LED 1230, the second stack of LED 1330 and the third stack of LED 1430 can be grown on different substrates, and the sequence of its formation is not limited to a specific sequence.
[0326] [0326] Referring to FIG. 37D, the first 1230 LED stack is coupled to the support substrate 1510 through a first bonding layer 1530. The first bonding layer 1530 can be formed previously on the supporting substrate 1510, and the reflective electrode 1250 can be attached to the first bonding layer 1530 for facing support substrate 1510. The first substrate 1210 is removed from the first stack of LED 1230 by chemical etching or the like. Therefore, the upper surface of the n-type semiconductor layer of the first
[0327] [0327] Then, a 1290 ohmic electrode is formed in the exposed region of the first 1230 LED stack. In order to reduce the ohmic contact resistance of the 1290 ohmic electrode, the 1290 ohmic electrode can be heat treated. The ohmic electrode 1290 can be formed in each pixel region, in order to correspond to the pixel regions.
[0328] [0328] Referring to FIG. 37E, the second battery of LED 1330 is coupled to the first battery of LED 1230, on which the ohmic electrode 1290 is formed, through a second connection layer 1550. The first color filter 1370 is connected to the second connection layer 1550 for face the first stack of LED 1230. The second layer of connection 1550 can be formed previously on the first stack of LED 1230, so that the first color filter 1370 can be turned over and connected to the second layer of connection 1550. The second substrate 31 can be separated from the second 1330 LED battery by a laser lifting or chemical lifting process.
[0329] [0329] Then, with reference to FIG. 36 and FIG. 37C, the third battery of LED 1430 is coupled to the second battery of LED 1330 through a third layer of connection 1570. The second color filter 1470 is connected to the third layer of connection 1570 to face the second battery of LED 1330. The third connection layer 1570 can be pre-arranged on the second stack of LED 1330, so that the second color filter 1470 can be turned over and connected to the third link layer 1570. The third substrate 1410 can be separated from the third stack of LED 1430 by a laser lifting or chemical lifting process. As such, a stack of light-emitting diodes for a display can be formed as shown in FIG. 36, which has the n-type semiconductor layer of the third LED stack 1430 exposed to the outside.
[0330] [0330] A display device, according to an exemplary modality, can be provided by standardizing the battery from the first to the third LED batteries 1230, 1330 and 1430 on the support substrate 1510 in pixel units, followed by the connection of the first to the third LED batteries to each other through interconnections. In the following, a display device according to exemplary modalities will be described.
[0331] [0331] FIG. 38 is a schematic circuit diagram of a display device according to an exemplary embodiment, and FIG. 39 is a schematic plan view of a display device according to an exemplary embodiment.
[0332] [0332] Referring to FIG. 38 and FIG. 39, a display device, according to an exemplary embodiment, can be operated in a passive matrix manner.
[0333] [0333] For example, since the stack of light emitting diodes for a display of FIG. 36 includes the first to third batteries of LED 1230, 1330 and 1430 stacked in the vertical direction, a pixel can include three light-emitting diodes R, G and B. A first light-emitting diode R can correspond to the first battery of LED 1230, a second light-emitting diode G can correspond to the second battery of LED 1330 and a third light-emitting diode B can correspond to the third battery of LED 1430.
[0334] [0334] In FIGS. 36 and 39, a pixel includes the first to the third light emitting diodes R, G and B, each of which corresponds to a sub-pixel. The anodes of the first to the third light-emitting diodes R, G and B are connected to a common line, for example, a data line and their cathodes are connected to different lines, for example, scanning lines.
[0335] [0335] In addition, each of the light-emitting diodes R, G and B can be triggered by a pulse width modulation or by changing the magnitude of the electric current, thus controlling the brightness of each subpixel.
[0336] [0336] Referring to FIG. 39, a plurality of pixels are formed by standardizing the stack of light emitting diodes 1000 of FIG. 36, and each of the pixels is connected to reflective electrodes 1250 and interconnect lines 1710, 1730 and 1750. As shown in Fig. 38, reflective electrode 1250 can be used as the Vdata data line and the 1710 interconnect lines , 1730 and 1750 can be formed as the scan lines.
[0337] [0337] The pixels can be arranged in a matrix form, in which the anodes of the light emitting diodes R, G and B of each pixel are commonly connected to the reflective electrode 1250, and their cathodes are connected to the 1710 interconnect lines , 1730, and 1750 separated from each other. Here, interconnect lines 1710, 1730 and 1750 can be used as Vscan scan lines.
[0338] [0338] FIG. 40 is an enlarged one-pixel plan view of the display device of FIG. 39, FIG. 41 is a schematic cross-sectional view taken along a line A-A of FIG. 40, and FIG. 42 is a schematic cross-sectional view taken along a line B-B of FIG. 40.
[0339] [0339] Referring to FIG. 39, FIG. 40, FIG. 41, and FIG. 42, in each pixel, a portion of the reflective electrode 1250, the ohmic electrode 1290 formed on the top surface of the first battery of LED 1230 (see FIG. 43H), a portion of the second transparent electrode p 1350 (see also FIG. 43H), a portion of the upper surface of the second LED battery 1330 (see FIG. 43J), a portion of the third transparent electrode p 1450 (see FIG. 43H) and the upper surface of the third LED battery 1430 are exposed to the outside.
[0340] [0340] The third LED battery 1430 may have a rough surface 1430a on its upper surface. The rough surface 1430a can be formed over the entire upper surface of the third LED stack 1430 or it can be formed in some regions thereof, as shown in FIG. 41.
[0341] [0341] A lower insulation layer 1610 can cover a side surface of each pixel. The lower insulation layer 1610 can be formed from a light transmitting material, such as SiO2. In this case, the lower insulation layer 1610 can cover the entire upper surface of the third LED stack
[0342] [0342] The bottom insulation layer 1610 may include an opening 1610a that exposes the top surface of the third LED stack 1430, an opening 1610b that exposes the top surface of the second LED stack 1330, an opening 1610c (see FIG. 43H) which exposes the ohmic electrode 1290 of the first 1230 LED battery, an opening 1610d that exposes the third transparent electrode
[0343] [0343] Interconnect lines 1710 and 1750 can be formed close to the first to the third LED batteries 1230, 1330 and 1430 on the support substrate 1510 and can be arranged in the lower insulation layer 1610 to be isolated from the first reflective electrode p 1250 A connection portion 1770a connects the third transparent electrode p 1450 to the reflective electrode 1250 and a connection portion 1770b connects the second transparent electrode p 1350 to the reflective electrode 1250, so that the anodes of the first battery of LED 1230, the second battery of LED 1330 and the third battery of LED 1430 are commonly connected to the reflective electrode 1250.
[0344] [0344] A connection portion 1710a connects the top surface of the third LED stack 1430 to the interconnect line 1710 and a connection portion 1750a connects the ohmic electrode 1290 in the first LED stack 1230 to the interconnect line 1750.
[0345] [0345] An upper insulation layer 1810 can be arranged on interconnect lines 1710 and 1730 and the lower insulation layer 1610 to cover the upper surface of the third stack of LED 1430. The upper insulation layer 1810 can have an opening 1810a that partially exposes the top surface of the second 1330 LED stack.
[0346] [0346] The interconnect line 1730 can be arranged in the upper insulating layer 1810, and the connection portion 1730a can connect the upper surface of the second stack of LED 1330 to the interconnect line 1730. The connection portion 1730a can pass through an upper portion of the interconnect line 1750 and is isolated from the interconnect line 1750 by the upper insulation layer 1810.
[0347] [0347] Although the electrodes of each pixel, according to the exemplary example illustrated, are described as being connected to the data line and the scanning lines, several implementations are possible. Furthermore, although interconnect lines 1710 and 1750 are described as being formed in the lower insulation layer 1610, and interconnect line 1730 is formed in the upper insulation layer 1810, the inventive concepts are not limited to this. For example, each of the interconnection lines 1710, 1730 and 1750 can be formed in the lower insulation layer 1610 and covered by the upper insulation layer 1810, which may have openings to expose the interconnection line 1730. In this structure, the portion of connection 1730a can connect the top surface of the second stack of LED 1330 to the interconnect line 1730 through the openings of the top insulation layer 1810.
[0348] [0348] Alternatively, interconnect lines 1710, 1730 and 1750 can be formed within support substrate 1510, and connection portions 1710a, 1730a and 1750a in the lower insulation layer 1610 can connect the ohmic electrode 1290, the upper surface from the second 1330 LED stack and the top surface of the third 1430 LED stack for the 1710, 1730 and 1750 interconnect lines.
[0349] [0349] FIG. 43A to FIG. 43K are schematic plan views that illustrate a method of manufacturing a display device including the pixel of FIG. 40 according to an exemplary modality.
[0350] [0350] First, the stack of light-emitting diodes 1000 described in FIG. 36 is prepared.
[0351] [0351] Then, with reference to FIG. 43A, a rough surface 1430a can be formed on the top surface of the third LED stack 1430. The rough surface 1430a can be formed on the top surface of the third LED stack 1430, so as to correspond to each pixel region. The rough surface 1430a can be formed by chemical engraving, for example, photo-enhanced chemical engraving (PEC) or the like.
[0352] [0352] The rough surface 1430a can be partially formed in each pixel region taking into account a region of the third LED stack 1430 to be recorded in the subsequent process, without being limited to it. Alternatively, the rough surface 1430a can be formed over the entire upper surface of the third LED stack 1430.
[0353] [0353] Referring to FIG. 43B, a region surrounding the third LED battery 1430 in each pixel is removed by recording to expose the third transparent electrode p 1450. As shown in Fig. 43B, the third LED battery 1430 can remain in a rectangular or square shape. The third stack of LED 1430 may have a plurality of depressions along its edges.
[0354] [0354] Referring to FIG. 43C, the upper surface of the second 1330 LED battery is exposed by removing the third exposed transparent electrode from the third p 1450 in areas other than a depression of the third 1430 LED battery. Therefore, the upper surface of the second 1330 LED battery is exposed around the third stack of LED 1430 and other depressions, excluding the depression in which the third transparent electrode p 1450 remains partially.
[0355] [0355] Referring to FIG. 43D, the second transparent electrode p 1350 is exposed by removing the second exposed 1330 LED battery in areas other than the depression of the third 1430 LED battery.
[0356] [0356] Referring to FIG. 43E, the ohmic electrode 1290 is exposed together with the top surface of the first 1230 LED cell by removing the second transparent electrode p 1350 exposed in areas other than the depression of the third 1430 LED cell. In this case, the 1290 ohmic electrode can be exposed in a depression. Therefore, the upper surface of the first 1230 LED cell is exposed around the third 1430 LED cell and an upper surface of the ohmic electrode 1290 is exposed in at least one of the depressions formed in the third 1430 LED cell.
[0357] [0357] Referring to FIG. 43F, the reflective electrode 1250 is exposed by removing an exposed portion of the first 1230 LED battery other than the ohmic electrode 1290 exposed in a depression. The reflective electrode 1250 is exposed around the third battery of LED 1430.
[0358] [0358] Referring to FIG. 43G, linear interconnect lines are formed by standardizing the reflective electrode 1250. Here, the supporting substrate 1510 can be exposed. The reflective electrode 1250 can connect pixels arranged in a line with each other between pixels arranged in a matrix (see FIG. 39).
[0359] [0359] Referring to FIG. 43H, a lower insulation layer 1610 (see FIG. 41 and FIG. 42) is formed to cover the pixels. The lower insulation layer 1610 covers the reflective electrode 1250 and the side surfaces of the first to third LED batteries 1230, 1330 and 1430. In addition, the lower insulation layer 1610 can at least partially cover the upper surface of the third LED battery. 1430. If the lower insulation layer 1610 is a transparent layer, such as a SiO2 layer, the lower insulation layer 1610 can cover the entire upper surface of the third stack of LED 1430. Alternatively, when the lower insulation layer 1610 includes a distributed Bragg reflector, the lower insulation layer 1610 can at least partially expose the upper surface of the third LED stack 1430, so that the light can be emitted to the outside.
[0360] [0360] The lower insulation layer 1610 may include an opening 1610a that exposes the third battery of LED 1430, an opening 1610b that exposes the second battery of LED 1330, an opening 1610c that exposes the ohmic electrode 1290, an opening 1610d that exposes the third transparent electrode p 1450, an opening 1610e that exposes the second transparent electrode p 1350 and an opening 1610f that exposes the reflective electrode 1250. One or more openings 1610f can be formed to expose the reflective electrode 1250.
[0361] [0361] Referring to FIG. 43I, interconnect lines 1710, 1750 and connecting parts 1710a, 1750a, 1770a and 1770b are formed. These can be formed by a lifting process or the like. Interconnect lines 1710 and 1750 are isolated from reflective electrode 1250 by lower insulation layer 1610. Connection portion 1710a electrically connects the third LED stack 1430 to interconnect line 1710, and connection portion 1750a electrically connects the ohmic electrode 1290 to the 1750 interconnect line, so that the first 1230 LED stack is electrically connected to the interconnect line
[0362] [0362] Referring to FIG. 43J, an upper insulation layer 1810 (see FIG. 41 and FIG. 42) covers interconnect lines 1710 and 1750 and connection parts 1710a, 1750a, 1770a and 1770b. The top insulation layer 1810 can also cover the entire top surface of the third LED stack
[0363] [0363] Referring to FIG. 43K, an interconnect line 1730 and a connection portion 1730a are formed. An interconnect line 1750 and a connection portion 1750a can be formed by a lifting process or the like. Interconnect line 1730 is arranged in the upper insulation layer 1810 and is isolated from reflective electrode 1250 and interconnect lines 1710 and 1750. Connection portion 1730a electrically connects the second stack of LED 1330 to interconnect line 1730. The portion connection cable 1730a can pass through an upper portion of interconnect line 1750 and is isolated from interconnect line 1750 by the upper insulation layer
[0364] [0364] As such, a pixel region as shown in FIG. 40 can be formed. In addition, as shown in FIG. 39, a plurality of pixels can be formed on the support substrate 1510 and can be connected to each other by the first reflective electrode p 1250 and the interconnect lines 1710, 1730 and 1750 to be operated in a passive matrix manner.
[0365] [0365] Although the display device above has been described as being configured to be operated in the passive matrix manner, the inventive concepts are not limited to these. More particularly, a display device according to some exemplary embodiments can be manufactured in a number of ways, so as to be operated in the passive matrix manner using the stack of light-emitting diodes shown in FIG. 36.
[0366] [0366] For example, although interconnect line 1730 is shown to be formed in the upper insulation layer 1810, interconnect line 1730 can be formed together with interconnect lines 1710 and 1750 in the lower insulation layer 1610 and the upper part. connection cable 1730a can be formed in the upper insulation layer 1810 to connect the second stack of LED 1330 to the interconnect line 1730. Alternatively, the interconnect lines 1710, 1730 and 1750 can be arranged within the support substrate 1510.
[0367] [0367] FIG. 44 is a schematic circuit diagram of a display device according to another exemplary embodiment. The display device, according to the illustrated example, can be operated in an active matrix manner.
[0368] [0368] Referring to FIG. 44, the drive circuit according to an exemplary embodiment includes at least two transistors Tr1, Tr2 and a capacitor. When a power source is connected to the selection lines Vrow1 to Vrow3 and the voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding LED. In addition, the corresponding capacitor is charged according to the values of Vdata1 to Vdata3. Since the activation state of a transistor Tr2 can be maintained by the charged voltage of the capacitor, the voltage of the capacitor can be maintained and applied to the light-emitting cells of LED1, LED3 and LED3, even when the power supply to Vrow1 is turned off. In addition, the electric current flowing in the light emitting diodes LED1 to LED3 can be changed depending on the values from Vdata1 to Vdata3. The electric current can be supplied continuously through the Vdd, so that the light can be emitted continuously.
[0369] [0369] Transistors Tr1, Tr2 and capacitor can be formed within the supporting substrate 1510. For example, thin film transistors formed on a silicon substrate can be used to drive the active matrix.
[0370] [0370] The light emitting diodes LED1 to LED3 can correspond to the first to third batteries of LED 1230, 1330 and 1430 stacked in one pixel, respectively. The anodes from the first to the third LED cells are connected to transistor Tr2 and their cathodes are connected to ground.
[0371] [0371] Although FIG. 44 show the circuit for activating the active matrix, according to an exemplary modality, other various types of circuits can be used. In addition, although the anodes of the light-emitting diodes LED1 to LED3 are described as being connected to different Tr2 transistors, and their cathodes are described as being connected to ground, the inventive concepts are not limited to these and the anodes of the light-emitting diodes can be connected to Vdd current sources and their cathodes can be connected to different transistors.
[0372] [0372] FIG. 45 is a schematic one-pixel plan view of a display device according to another exemplary embodiment. The pixel described herein can be one of a plurality of pixels arranged on the support substrate 1511.
[0373] [0373] Referring to FIG. 45, the pixels according to an exemplary embodiment are generally similar to the pixels described with reference to FIG. 39 through FIG. 42, except that the supporting substrate 1511 is a thin film transistor panel, including transistors and capacitors, and the reflecting electrode is disposed in a lower region of the first LED stack.
[0374] [0374] The cathode of the third LED stack is connected to the support substrate 1511 through the connection portion 1711a. For example, as shown in FIG. 45, the cathode of the third LED stack can be connected to the ground via the electrical connection to the supporting substrate 1511. The cathodes of the second LED stack and the first LED stack can also be connected to the ground via an electrical connection to the support substrate. support 1511 through connection portions 1731a and 1751a.
[0375] [0375] The reflective electrode is connected to the transistors Tr2 (see FIG. 44) inside the support substrate 1511. The third transparent electrode p and the second transparent electrode p are also connected to the transistors Tr2 (see FIG. 44) inside the support substrate 1511 through connection portions 1771a and 1731b.
[0376] [0376] In this way, the first to the third LED batteries are connected to each other, thus constituting a circuit for activating the active matrix, as shown in FIG. 44.
[0377] [0377] Although FIG. 45 show the electrical connection of a pixel for activating the active matrix, according to an exemplary mode, the inventive concepts are not limited to these, and the circuit for the display device can be modified in several circuits for activating the active matrix of many ways.
[0378] [0378] Furthermore, while the reflective electrode 1250, the second transparent electrode p 1350 and the third transparent electrode p 1450 of FIG. 36 are described as forming ohmic contact with the corresponding p-type semiconductor layer of each of the first 1230 LED batteries, the second 1330 LED battery and the third 1430 LED battery, and the 1290 ohmic electrode forms ohmic contact with the layer type n semiconductor of the first 1230 LED cell, the type n semiconductor layer of each of the second 1330 LED cells and the third 1430 LED cell is not provided with a separate ohmic contact layer. When the pixels are small in size of 200 µm or less, there is less difficulty in propagating the current, even without the formation of a separate ohmic contact layer in the n-type semiconductor layer. However, according to some exemplary modalities, a transparent electrode layer can be arranged on the type n semiconductor layer of each of the LED cells, in order to guarantee the current propagation.
[0379] [0379] Furthermore, although the first to the third LED batteries 1230, 1330 and 1430 are coupled together by means of the connecting layers 1530, 1550 and 1570, the inventive concepts are not limited to these and the first to the third batteries of LEDs 1230, 1330, and 1430 can be connected to each other in various sequences and using various structures.
[0380] [0380] According to exemplary modalities, since it is possible to form a plurality of pixels at the wafer level using the light emitting diode stack 1000 for a display, the individual assembly of light emitting diodes can be avoided. In addition, the stack of light emitting diodes according to the exemplary modalities has the structure in which the first to the third 1230, 1330 and 1430 LED batteries are stacked in the vertical direction, thus ensuring an area for sub-pixels in a limited area of pixels. In addition, the battery of light emitting diodes according to the exemplary modalities allows the light generated from the first 1230 LED battery, the second 1330 LED battery and the third 1430 LED battery to be emitted out of it, reducing thus the loss of light.
[0381] [0381] FIG. 46 is a schematic cross-sectional view of a stack of LEDs for a display according to an exemplary embodiment.
[0382] [0382] Referring to FIG. 46, the stack of light emitting diodes 2000 includes a support substrate 2510, a first stack of LED 2230, a second stack of LED 2330, a third stack of LED 2430, a reflective electrode 2250, an ohmic electrode 2290, a second transparent electrode 2350, a third transparent electrode p 2450, an insulation layer 2270, a first connection layer 2530, a second connection layer 2550 and a third layer of connection 2570. In addition, the first stack of LED 2230 may include a ohmic contact portion 2230a for ohmic contact.
[0383] [0383] In general, light can be generated from the first LED battery by the light emitted by the second LED battery and the light can be generated from the second LED battery by the light emitted by the third LED battery. As such, a color filter can be interposed between the second LED battery and the first LED battery and between the third LED battery and the second LED battery.
[0384] [0384] However, while color filters can prevent light interference, the formation of color filters increases the complexity of manufacturing. A display device in accordance with exemplary modalities can suppress the generation of secondary light between the LED batteries without the provision of color filters between them.
[0385] [0385] Therefore, in some exemplary embodiments, the interference of light between the LED cells can be reduced by controlling the bandwidth of each of the LED cells, which will be described in more detail below.
[0386] [0386] The support substrate 2510 supports the semiconductor cells 2230, 2330 and 2430. The support substrate 2510 may include a circuit on a surface of the same or in it, but the inventive concepts are not limited to it. The support substrate 2510 can include, for example, a Si substrate, a Ge substrate, a sapphire substrate, a standardized sapphire substrate, a glass substrate or a standardized glass substrate.
[0387] [0387] Each of the first 2230 LED stack, the second 2330 LED stack and the 2430 LED stack includes a n-type semiconductor layer, a p-type semiconductor layer and an active layer interposed between them. The active layer can have a multi-quantum well structure.
[0388] [0388] L1 light generated from the first 2230 LED battery has a longer wavelength than L2 light generated from the second 2330 LED battery, which has a longer wavelength than the L3 light generated at from the third 2430 LED battery.
[0389] [0389] The first 2230 LED battery can be an inorganic light emitting diode configured to emit red light,
[0390] [0390] Although the stack of light emitting diodes 2000 of FIG. 46 is illustrated as including three 2230, 2330 and 2430 LED batteries, the inventive concepts are not limited to a specific number of LED batteries on top of each other. For example, a battery of LEDs to emit yellow light can be additionally added between the first battery of LED 2230 and the second battery of LED 2330.
[0391] [0391] Both surfaces of each of the first to third LED batteries 2230, 2330 and 2430 are a n-type semiconductor layer and a p-type semiconductor layer, respectively. In FIG. 46, each from the first to the third stack of LEDs 2230, 2330 and 2430 is described as having an upper surface of type n and a lower surface of type p. Since the third 2430 LED stack has a top surface of type n, a rough surface can be formed on the top surface of the third 2430 LED stack through chemical etching or the like. However, the inventive concepts are not limited to them, and the types of semiconductors on the top and bottom surfaces of each of the LED cells can be formed alternatively.
[0392] [0392] The first 2230 LED battery is placed near the support substrate 2510, the second 2330 LED battery is placed on the first 2230 LED battery and the third LED battery
[0393] [0393] In an exemplary embodiment, the n-type semiconductor layer of the first 2230 LED stack can have a band gap greater than the band gap of the active layer of the first 2230 LED stack and narrower than the band gap of the first 2230 LED stack. active layer of the second 2330 LED stack. Therefore, a portion of light generated from the second 2330 LED stack can be absorbed by the n-type semiconductor layer of the first 2230 LED stack before reaching the active layer of the first 2330 LED stack. LED 2230. As such, the intensity of the light generated in the active layer of the first battery of LED 2230 can be reduced by the light generated from the second battery of LED 2330.
[0394] [0394] In addition, the n-type semiconductor layer of the second 2330 LED stack has a bandwidth greater than the active layer bandwidth of each of the first 2230 LED batteries and the second 2330 LED stack and more narrower than the band gap of the active layer of the third 2430 LED stack. Therefore, a portion of light generated from the third 2430 LED stack can be absorbed by the n-type semiconductor layer of the second 2330 LED stack before reaching the active layer of the second 2330 LED battery. As such, the intensity of the light generated in the second 2330 LED battery or the first 2230 LED battery can be reduced by the light generated from the third 2430 LED battery.
[0395] [0395] The p-type semiconductor layer and the n-type semiconductor layer of the third 2430 LED stack have wider band intervals than the active layers of the first 2230 LED stack and the second 2330 LED stack, thus transmitting the generated light by the first and second LED batteries 2230 and 2330 through them.
[0396] [0396] According to an exemplary modality, it is possible to reduce light interference between the 2230, 2330 and 2430 LED cells by adjusting the band intervals of the n-type semiconductor layers or the p-type semiconductor layers of the first and second cells LEDs 2230 and 2330, which can avoid the need for other components, such as color filters. For example, the light intensity generated from the second 2330 LED battery and emitted to the outside can be about 10 times or more than the light intensity generated from the first 2230 LED battery by the light generated from the second 2330 LED battery. Likewise, the intensity of light generated from the third 2430 LED battery and emitted to the outside can be about 10 times or more the light intensity generated from the second 2330 LED battery caused by light generated from the third stack of LED 2430. In this case, the intensity of light generated from the third stack of LED 2430 and emitted to the outside can be about 10 times or more the intensity of the light generated from the first stack 2230 LED light caused by the light generated from the third 2430 LED battery
[0397] [0397] The reflective electrode 2250 forms ohmic contact with the p-type semiconductor layer of the first 2230 LED cell and reflects the light generated from the first 2230 LED cell. For example, the 2250 reflective electrode may include a contact layer ohmic 2250a and a reflective layer 2250b.
[0398] [0398] The ohmic contact layer 2250a partially contacts the p-type semiconductor layer of the first 2230 LED stack. To prevent light absorption by the ohmic contact layer 2250a, a region in which the ohmic contact layer 2250a comes into contact. Contact with the p-type semiconductor layer may not exceed about 50% of the total area of the p-type semiconductor layer. The reflective layer 2250b covers the ohmic contact layer 2250a and the insulating layer 2270. As shown in Fig. 46, the reflective layer 2250b can cover substantially the entire ohmic contact layer 2250a, without being limited thereto. Alternatively, the reflective layer 2250b can cover a portion of the ohmic contact layer 2250a.
[0399] [0399] Since the reflective layer 2250b covers the insulation layer 2270, an omnidirectional reflector can be formed by the stacked structure of the first 2230 LED stack with a relatively high refractive index and the 2270 insulation layer with a refractive index. relatively low, and the reflective layer 2250b. The reflective layer 2250b can cover about 50% or more of the area of the first 2230 LED battery or most of the first 2230 LED battery, thus improving luminous efficiency.
[0400] [0400] The ohmic contact layer 2250a and the reflective layer 2250b can be formed by metal layers, which may include
[0401] [0401] The insulation layer 2270 is interposed between the supporting substrate 2510 and the first 2230 LED stack and has openings that expose the first 2230 LED stack. The ohmic contact layer 2250a is connected to the first 2230 LED stack in the 2270 insulation layer openings.
[0402] [0402] The ohmic electrode 2290 is disposed on the top surface of the first 2230 LED battery. In order to reduce the ohmic contact resistance of the ohmic electrode 2290, the ohmic contact portion 2230a may protrude from the upper surface of the first 2230 LED battery. The ohmic electrode 2290 can be arranged in the ohmic contact portion 2230a.
[0403] [0403] The second transparent p 2350 electrode forms ohmic contact with the p type semiconductor layer of the second 2330 LED stack. The second transparent p 2350 electrode can be formed by a metal layer or a conductive oxide layer that is transparent to the red light and green light.
[0404] [0404] The third transparent electrode p 2450 forms ohmic contact with the semiconductor type p of the third stack of LED 2430. The third transparent electrode p 2450 can be formed by a metal layer or a layer of conductive oxide that is transparent to red light, green light and blue light.
[0405] [0405] The reflective electrode 2250, the second transparent electrode p 2350 and the third transparent electrode p 2450 can help in the propagation of current through the ohmic contact with the p-type semiconductor layer of the corresponding LED cells.
[0406] [0406] The first connection layer 2530 couples the first stack of LED 2230 to the support substrate 2510. As shown in Fig. 46, the reflective electrode 2250 can join with the first connection layer 2530. The first connection layer 2530 it can be a transmissive layer or opaque to light.
[0407] [0407] The second layer of connection 2550 couples the second battery of LED 2330 to the first battery of LED 2230. As shown in Fig. 46, the second layer of connection 2550 can join the first battery of LED 2230 and the second transparent electrode p 2350. The ohmic electrode 2290 can be covered by the second connection layer 2550. The second connection layer 2550 transmits light generated from the first stack of LED 2230. The second connection layer 2550 can be formed from a transmitting connection material light, for example, a light-transmitting organic binding agent or light-transmitting spin-on-glass. Examples of the light-transmitting organic binding agent can include SU8, poly (methyl methacrylate) (PMMA), polyimide, Parylene, benzocyclobutene (BCB) and the like. In addition, the second 2330 LED battery can be connected to the first 2230 LED battery by plasma connection or the like.
[0408] [0408] The third layer of connection 2570 couples the third battery of LED 2430 to the second battery of LED 2330. As shown in Fig. 46, the third layer of connection 2570 can join the second battery of LED 2330 and the third electrode transparent p
[0409] [0409] Each of the second link layer 2550 and the third link layer 2570 can transmit light generated from the third stack of LED 2430 and light generated from the second stack of LED 2330.
[0410] [0410] FIG. 47A to FIG. 47E are schematic cross-sectional views illustrating a method of fabricating a stack of light-emitting diodes for a display according to an exemplary embodiment.
[0411] [0411] Referring to FIG. 47A, a first 2230 LED stack is grown on a first 2210 substrate. The first 2210 substrate can be, for example, a GaAs substrate. The first 2230 LED stack consists of semiconductor layers based on AlGaInP and includes a n-type semiconductor layer, an active layer and a p-type semiconductor layer. In some exemplary embodiments, the n-type semiconductor layer may have an energy gap capable of absorbing the light generated from the second 2330 LED stack and the p-type semiconductor layer may have an energy gap capable of absorbing the generated light. from the second 2330 LED battery.
[0412] [0412] A 2270 insulation layer is formed on the first 2230 LED stack and standardized to form openings in it. For example, a SiO2 layer is formed on the first 2230 LED stack and a photoresistor is deposited on the SiO2 layer, followed by photolithography and development to form a photoresistor pattern. Then, the SiO2 layer is standardized through the photoresistor pattern used as a recording mask, thus forming the 2270 insulation layer having the openings.
[0413] [0413] Then, an ohmic contact layer 2250a is formed in the openings of the 2270 insulation layer. The ohmic contact layer 2250a can be formed by a lifting process or the like. After the ohmic contact layer 2250a is formed, a reflective layer 2250b is formed to cover the ohmic contact layer 2250a and the insulating layer 2270. The reflective layer 2250b can be formed by a lifting process or the like. The reflective layer 2250b can cover a portion of the ohmic contact layer 2250a or all of it. The ohmic contact layer 2250a and the reflective layer 2250b form a reflective electrode 2250.
[0414] [0414] The reflective electrode 2250 forms ohmic contact with the p-type semiconductor layer of the first 2230 LED stack and will therefore be referred to hereinafter as a first reflective electrode p 2250.
[0415] [0415] Referring to FIG. 47B, a second 2330 LED stack is grown on a second 2310 substrate and a second transparent p 2350 electrode is formed on the second 2330 LED stack. The second 2330 LED stack can be formed by GaN-based semiconductor layers and may include a layer of GaInN well. The second substrate 2310 is a substrate on which the GaN-based semiconductor layers can be grown on it and is different from the first 2210 substrate. The composition ratio of GaInN to the second 2330 LED stack can be determined so that the second 2330 LED battery emit green light. The second transparent p 2350 electrode forms ohmic contact with the p-type semiconductor layer of the second 2330 LED cell. The second 2330 LED cell may include an n-type semiconductor layer, an active layer and a p-type semiconductor layer. In some exemplary embodiments, the n-type semiconductor layer of the second 2330 LED cell may have an energy band gap capable of absorbing the light generated from the third 2430 LED cell, and the p-type semiconductor layer of the second cell 2330 LED can have an energy range capable of absorbing the light generated from the third 2430 LED stack.
[0416] [0416] Referring to FIG. 47C, a third stack of LED 2430 is grown on a third substrate 2410 and a third transparent electrode p 2450 is formed on the third stack of LED 2430. The third stack of LED 2430 can be formed of semiconductor layers based on GaN and may include a GaInN well layer. The third substrate 2410 is a substrate on which the GaN-based semiconductor layers can be grown on it and is different from the first 2210 substrate. The GaInN composition ratio for the third 2430 LED stack can be determined so that the third stack LED light emits blue light. The third p 2450 transparent electrode forms ohmic contact with the p-type semiconductor layer of the third 2430 LED battery.
[0417] [0417] As such, the first LED stack 2230, the second LED stack 2330 and the third LED stack 2430 are grown on different substrates, and the formation sequence of the same is not limited to a specific sequence.
[0418] [0418] Referring to FIG. 47D, the first 2230 LED stack is coupled to the support substrate 2510 through a first connection layer 2530. The first connection layer 2530 can be formed previously on the support substrate 2510 and the reflective electrode 2250 can be connected to the first layer connector 2530 to face the support substrate 2510. The first substrate 2210 is removed from the first stack of LED 2230 by chemical etching or the like. Therefore, the upper surface of the n-type semiconductor layer of the first 2230 LED stack is exposed.
[0419] [0419] Then, a 2290 ohmic electrode is formed in the exposed region of the first 2230 LED stack. In order to reduce the ohmic contact resistance of the 2290 ohmic electrode, the 2290 ohmic electrode can be heat treated. The ohmic electrode 2290 can be formed in each pixel region to correspond to the pixel regions.
[0420] [0420] Referring to FIG. 47E, the second LED battery 2330 is coupled to the first LED battery 2230, in which the ohmic electrode 2290 is formed, through a second connection layer 2550. The second transparent electrode p 2350 is connected to the second connection layer 2550 to face the first stack of LED 2230. The second layer of connection 2550 can be formed previously in the first stack of LED 2230, so that the second transparent electrode p 2350 can be turned over and connected to the second layer of connection 2550. The second substrate 2310 can be separated from the second 2330 LED battery by a laser lifting or chemical lifting process.
[0421] [0421] Then, with reference to FIG. 46 and FIG. 47C, the third battery of LED 2430 is coupled to the second battery of LED 2330 through a third layer of connection 2570. The third transparent electrode p 2450 is connected to the third layer of connection 2570 to face the second battery of LED 2330. The third connection layer 2570 can be formed previously on the second stack of LED 2330, so that the third transparent electrode p 2450 can be turned and connected to the third connection layer
[0422] [0422] A display device can be formed by standardizing the stack of the first to the third LED batteries 2230, 2330 and 2430 arranged on the supporting substrate 2510 in pixel units, followed by the connection of the first to the third LED battery 2230, 2330 and 2430 to one another through interconnections. However, inventive concepts are not limited to these. For example, a display device can be manufactured by dividing the battery from the first to the third 2230, 2330 and 2430 LED batteries into individual units and transferring the first to the third 2230, 2330 and 2430 LED batteries to other support substrates, such as as a printed circuit board.
[0423] [0423] FIG. 48 is a schematic circuit diagram of a display device according to an exemplary embodiment. FIG. 49 is a schematic plan view of a display device according to an exemplary embodiment.
[0424] [0424] Referring to FIG. 48 and FIG. 49, the display device, according to an exemplary modality, can be implemented to be activated in a passive way.
[0425] [0425] The stack of light emitting diodes for a display shown in FIG. 46 has the structure including the first to the third LED batteries 2230, 2330 and 2430 stacked in the vertical direction. As a pixel includes three light-emitting diodes R, G and B, a first light-emitting diode R can correspond to the first LED stack 2230, a second light-emitting diode G can correspond to the second LED stack 2330 and a third diode light emitter B can correspond to the third LED battery
[0426] [0426] Referring to FIGS. 48 and 49, a pixel includes the first to third light emitting diodes R, G and B, each of which may correspond to a sub-pixel. The anodes of the first to the third light-emitting diodes R, G and B are connected to a common line, for example, a data line and their cathodes are connected to different lines, for example, scanning lines. For example, in a first pixel, the anodes from the first to the third light-emitting diodes R, G and B are commonly connected to a Vdata1 data line and their cathodes are connected to the Vscan1-1, Vscan1-2 scan lines, and Vscan1-3, respectively. As such, the light emitting diodes R, G and B at each pixel can be activated independently.
[0427] [0427] In addition, each of the light-emitting diodes R, G and B can be triggered by a pulse width modulation or by changing the magnitude of the electrical current to control the brightness of each subpixel.
[0428] [0428] Referring to FIG. 49, a plurality of pixels are formed by patterning the stack of FIG. 46, and each of the pixels is connected to the reflective electrodes 2250 and the interconnecting lines 2710, 2730 and 2750. As shown in Fig. 48, the reflective electrode 2250 can be used as the Vdata data line and the 2710 interconnect lines. , 2730 and 2750 can be formed as the scan lines.
[0429] [0429] The pixels can be arranged in a matrix form, in which the anodes of the light-emitting diodes R, G and B of each pixel are commonly connected to the reflective electrode 2250, and their cathodes are connected to the interconnecting lines 2710 , 2730, and 2750 separated from each other. Here, interconnect lines 2710, 2730 and 2750 can be used as Vscan scan lines.
[0430] [0430] FIG. 50 is an enlarged one-pixel plan view of the display device of FIG. 49. FIG. 51 is a schematic cross-sectional view taken along a line A-A of FIG. 50, and FIG. 52 is a schematic cross-sectional view taken along a line B-B of FIG. 50.
[0431] [0431] Referring to FIGS. 49 to 52, at each pixel, a portion of the reflective electrode 2250, the ohmic electrode 2290 formed on the top surface of the first 2230 LED battery (see FIG. 53H), a portion of the second transparent electrode p 2350 (see FIG. 53H) , a portion of the upper surface of the second LED battery 2330 (see FIG. 53J), a portion of the third transparent electrode p 2450 (see FIG. 53H) and the upper surface of the third LED battery 2430 are exposed to the outside.
[0432] [0432] The third 2430 LED battery may have a rough surface 2430a on its upper surface. The rough surface 2430a can be formed over the entire upper surface of the third LED stack 2430 or it can be formed in some regions of it.
[0433] [0433] A lower insulation layer 2610 can cover a side surface of each pixel. The lower insulation layer 2610 can be formed from a light transmitting material, such as SiO2. In this case, the bottom insulation layer 2610 can substantially cover the entire top surface of the third 2430 LED stack. Alternatively, the bottom insulation layer 2610 may include a Bragg reflector distributed to reflect the light traveling towards the side surfaces of the first to third batteries of LEDs 2230, 2330 and 2430. In this case, the lower insulation layer 2610 may partially expose the upper surface of the third battery of LED 2430. Alternatively, the lower insulation layer 2610 may be an insulating layer to the black base that absorbs light. In addition, an electrically floating reflective metallic layer can also be formed in the lower insulation layer 2610 to reflect the light emitted through the side surfaces of the first to third LED batteries 2230, 2330 and 2430.
[0434] [0434] The bottom insulation layer 2610 may include an opening 2610a that exposes the top surface of the third LED stack 2430, an opening 2610b that exposes the top surface of the second LED stack 2330, an opening 2610c (see FIG. 53H) which exposes the ohmic electrode 2290 of the first stack of LED 2230, an opening 2610d that exposes the third transparent electrode 2450, an opening 2610e that exposes the second transparent electrode 2350 and openings 2610f that expose the first reflective electrode p 2250.
[0435] [0435] The interconnection lines 2710 and 2750 can be formed close to the first to the third LED batteries 2230, 2330 and 2430 on the support substrate 2510 and can be arranged in the lower insulation layer 2610 to be isolated from the first reflective electrode 2250. A connection portion 2770a connects the third transparent electrode p 2450 to the reflective electrode 2250 and a connection portion 2770b connects the second transparent electrode p 2350 to the reflective electrode 2250, so that the anodes of the first battery of LED 2230, the second battery of LED 2330 and the third stack of LED 2430 are commonly connected to the reflective electrode 2250.
[0436] [0436] A connection portion 2710a connects the top surface of the third battery of LED 2430 to the interconnect line 2710 and a connection portion 2750a connects the ohmic electrode 2290 in the first battery of LED 2230 to the interconnect line 2750.
[0437] [0437] An upper insulation layer 2810 can be arranged on interconnect lines 2710 and 2730 and the lower insulation layer 2610 to cover the upper surface of the third 2430 LED stack. The upper insulation layer 2810 can have an opening 2810a that partially exposes the top surface of the second 2330 LED stack.
[0438] [0438] The interconnect line 2730 can be arranged in the upper insulation layer 2810, and the connection portion 2730a can connect the upper surface of the second stack of LED 2330 to the interconnect line 2730. The connection portion 2730a can pass through an upper portion of the interconnect line 2750 and is isolated from the interconnect line 2750 by the upper insulation layer 2810.
[0439] [0439] Although the electrodes of each pixel are described as connected to the data line and the scan lines, the inventive concepts are not limited to these. In addition, while interconnect lines 2710 and 2750 are described as being formed in the lower insulation layer 2610 and interconnect line 2730 is described as being formed in the upper insulation layer 2810, the inventive concepts are not limited to these. For example, all interconnect lines 2710, 2730 and 2750 can be formed in the lower insulation layer 2610 and can be covered by the upper insulation layer 2810, which may have openings that expose the interconnect line 2730. In this way, the portion connector 2730a can connect the upper surface of the second 2330 LED stack to the interconnect line 2730 through the openings of the upper insulation layer 2810.
[0440] [0440] Alternatively, interconnect lines 2710, 2730 and 2750 can be formed within the supporting substrate 2510, and connection portions 2710a, 2730a and 2750a in the lower insulation layer 2610 can connect the ohmic electrode 2290, the upper surface of the first 2230 LED stack and the top surface of the third 2430 LED stack for the interconnect lines 2710, 2730 and 2750.
[0441] [0441] According to an exemplary embodiment, the L1 light generated from the first LED battery 2230 is emitted to the outside through the second and third LED batteries 2330 and 2430, and the L2 light generated from the second battery of LEDs LED 2330 is emitted to the outside via the third battery of LED 2430. In addition, a portion of L3 light generated from the third battery of LED 2430 can enter the second pile of LED 2330 and a portion of L2 light generated from the second 2330 LED battery can enter the first 2230 LED battery. In addition, a secondary light can be generated from the second 2330 LED battery by the L3 light and a secondary light can also be generated from the first 2230 LED battery. by the L2 light. However, this secondary light may be of low intensity.
[0442] [0442] FIG. 53A to FIG. 53K are schematic plan views that illustrate a method of manufacturing a display device according to an exemplary embodiment. In the following, the following descriptions will be given with reference to the pixel of FIG.
[0443] [0443] First, the stack of light emitting diodes 2000 described in FIG. 46 is prepared.
[0444] [0444] Referring to FIG. 53A, a rough surface 2430a can be formed on the top surface of the third LED stack
[0445] [0445] The rough surface 2430a can be partially formed in each pixel region taking into account a region of the third LED stack 2430 to be recorded in the subsequent process, without being limited to it. Alternatively, the rough surface 2430a can be formed over the entire upper surface of the third LED stack 2430.
[0446] [0446] Referring to FIG. 53B, a region surrounding the third 2430 LED battery in each pixel is removed by recording to expose the third transparent electrode p 2450. As shown in Fig. 53B, the third 2430 LED battery can remain in a rectangular or square shape. The third stack of LED 2430 may have a plurality of depressions formed along its edges.
[0447] [0447] Referring to FIG. 53C, the upper surface of the second 2330 LED battery is exposed by removing the third transparent electrode p 2450 exposed in areas other than a depression. Therefore, the upper surface of the second LED battery 2330 is exposed around the third LED battery 2430 and in depressions other than the depression in which the third transparent electrode p 2450 remains partially.
[0448] [0448] Referring to FIG. 53D, the second transparent p 2350 electrode is exposed by removing the second exposed 2330 LED battery in areas other than a depression.
[0449] [0449] Referring to FIG. 53E, ohmic electrode 2290 is exposed along with the top surface of the first 2230 LED battery by removing the second exposed transparent electrode p 2350 in areas other than a depression. Here, the ohmic electrode 2290 can be exposed in a depression. Accordingly, the upper surface of the first 2230 LED battery is exposed around the third 2430 LED battery and an upper surface of the 2290 ohmic electrode is exposed in at least one of the depressions formed in the third 2430 LED battery.
[0450] [0450] Referring to FIG. 53F, the reflective electrode 2250 is exposed by removing an exposed portion of the first 2230 LED battery in areas other than a depression. As such, the reflective electrode 2250 is exposed around the third LED stack 2430.
[0451] [0451] Referring to FIG. 53G, linear interconnect lines are formed by standardizing the reflective electrode 2250. Here, the support substrate 2510 can be exposed. The reflective electrode 2250 can connect pixels arranged in a line with each other between pixels arranged in a matrix (see FIG. 49).
[0452] [0452] Referring to FIG. 53H, a lower insulation layer 2610 (see FIG. 51 and FIG. 52) is formed to cover the pixels. The lower insulation layer 2610 covers the reflective electrode 2250 and the side surfaces of the first to third LED batteries 2230, 2330 and 2430. In addition, the lower insulation layer 2610 can partially cover the upper surface of the third LED battery 2430. If the bottom insulation layer 2610 is a transparent layer, such as a SiO2 layer, the bottom insulation layer 2610 can cover substantially the entire upper surface of the third 2430 LED stack. Alternatively, the bottom insulation layer 2610 may include a reflector Bragg distributed. In this case, the lower insulation layer 2610 can partially expose the upper surface of the third LED stack 2430 to allow light to be emitted to the outside.
[0453] [0453] The bottom insulation layer 2610 may include an opening 2610a that exposes the third battery of LED 2430, an opening 2610b that exposes the second battery of LED 2330, an opening 2610c that exposes the ohmic electrode 2290, an opening 2610d that exposes the third transparent electrode p 2450, an opening 2610e that exposes the second transparent electrode p 2350 and an opening 2610f that exposes the reflective electrode 2250. The opening 2610f that exposes the reflective electrode 2250 can be formed singularly or plurally.
[0454] [0454] Referring to FIG. 53I, interconnection lines 2710 and 2750 and connection parts 2710a, 2750a, 2770a and 2770b are formed by a lifting process or the like. The interconnect lines 2710 and 2750 are isolated from the reflective electrode 2250 by the lower insulation layer 2610. The connection portion 2710a electrically connects the third LED stack 2430 to the interconnect line 2710, and the connection portion 2750a electrically connects the ohmic electrode. 2290 to interconnect line 2750, so that the first stack of LED 2230 is electrically connected to interconnect line 2750. The connection portion 2770a electrically connects the third transparent electrode p 2450 to the first reflective electrode 2250 and the connection portion 2770b connects electrically the second transparent electrode p 2350 to the first reflective electrode 2250.
[0455] [0455] Referring to FIG. 53J, an upper insulation layer 2810 (see FIG. 51 and FIG. 52) covers interconnect lines 2710, 2750 and connection parts 2710a, 2750a, 2770a and 2770b. The top insulation layer 2810 can also substantially cover the entire top surface of the third 2430 LED stack. The top insulation layer 2810 has an opening 2810a that exposes the top surface of the second 2330 LED stack. The top insulation layer 2810 can be formed, for example, by silicon oxide or silicon nitride and may include a distributed Bragg reflector. When the top insulation layer 2810 includes the distributed Bragg reflector, the top insulation layer 2810 can expose at least part of the top surface of the third 2430 LED stack to allow light to be emitted to the outside.
[0456] [0456] Referring to FIG. 53K, an interconnect line 2730 and a connection portion 2730a are formed. An interconnect line 2750 and a connection portion 2750a can be formed by a lifting process or the like. The interconnect line 2730 is arranged in the upper insulating layer 2810 and is isolated from the reflective electrode 2250 and interconnect lines 2710 and 2750. The connection portion 2730a electrically connects the second battery of LED 2330 to the interconnect line 2730. The portion connection cable 2730a can pass through an upper portion of the interconnect line 2750 and is isolated from the interconnect line 2750 by the upper insulation layer
[0457] [0457] As such, a pixel region shown in FIG. 50 can be formed. In addition, as shown in FIG. 49, a plurality of pixels can be formed on the support substrate 2510 and can be connected to each other by the first reflective electrode p 2250 and the interconnect lines 2710, 2730 and 2750, to be operated in a passive matrix manner.
[0458] [0458] Although the above describes a method of manufacturing a display device that can be operated in the passive matrix manner, the inventive concepts are not limited to these. More particularly, the display device according to exemplary embodiments can be manufactured in a number of ways, so as to be operated in the passive matrix manner using the stack of light-emitting diodes shown in FIG. 46.
[0459] [0459] For example, while interconnect line 2730 is described as being formed in the upper insulation layer 2810, interconnect line 2730 can be formed in conjunction with interconnect lines 2710 and 2750 in the lower insulation layer 2610 and the connection part 2730a can be formed in the upper insulation layer 2810 to connect the second stack of LED 2330 to the interconnect line 2730. Alternatively, the interconnect lines 2710, 2730, 2750 can be arranged within the supporting substrate 2510.
[0460] [0460] FIG. 54 is a schematic circuit diagram of a display device according to another exemplary embodiment. The circuit diagram of FIG. 54 refers to a display device activated in an active matrix manner.
[0461] [0461] Referring to FIG. 54, the drive circuit according to an exemplary embodiment includes at least two transistors Tr1, Tr2 and a capacitor. When a power source is connected to the selection lines Vrow1 to Vrow3 and the voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding LED. In addition, the corresponding capacitors are charged according to the values from Vdata1 to Vdata3. As the activation state of transistor Tr2 can be maintained by the charged voltage of the capacitor, the voltage of the capacitor can be maintained and applied to the light-emitting cells of LED1, LED3 and LED3, even when the power supply to Vrow1 is turned off. In addition, the electric current flowing in the light emitting diodes LED1 to LED3 can be changed depending on the values from Vdata1 to Vdata3. The electric current can be supplied continuously through Vdd and, therefore, the light can be emitted continuously.
[0462] [0462] Transistors Tr1, Tr2 and capacitor can be formed within the supporting substrate 2510. For example, thin film transistors formed on a silicon substrate can be used to drive the active matrix.
[0463] [0463] Here, the light emitting diodes LED1 to LED3 can correspond to the first to third batteries of LEDs 2230, 2330 and 2430 stacked in one pixel, respectively. The anodes from the first to the third LED cells 2230, 2330 and 2430 are connected to transistor Tr2 and their cathodes are connected to ground.
[0464] [0464] Although FIG. 54 show the circuit for activating the active matrix according to an exemplary modality, other types of circuits can be used in several ways. In addition, although the anodes of the light-emitting diodes LED1 to LED3 are described as being connected to different transistors Tr2 and their cathodes are described as being connected to ground, the anodes of the light-emitting diodes can be connected to the Vdd and their cathodes can be connected to different transistors in some exemplary modalities.
[0465] [0465] FIG. 55 is a schematic plan view of a display device according to another exemplary embodiment. In the following, the following description will be given with reference to a pixel among a plurality of pixels arranged on the support substrate 2511.
[0466] [0466] Referring to FIG. 55, the pixel according to an exemplary embodiment is substantially similar to the pixel described with reference to FIG. 49 through FIG. 52, except that the supporting substrate 2511 is a thin film transistor panel including transistors and capacitors and the reflective electrode 2250 is arranged in a lower region of the first 2230 LED stack.
[0467] [0467] The cathode of the third LED stack 2430 is connected to the support substrate 2511 through the connection portion 2711a. For example, as shown in FIG. 54, the cathode of the third LED stack 2430 can be connected to the ground via the electrical connection to the supporting substrate 2511. The cathodes of the second LED stack 2330 and the first LED stack 2230 can also be connected to the ground via electrical connection. support substrate 2511 through connection portions 2731a and 2751a.
[0468] [0468] The reflective electrode is connected to the transistors Tr2 (see FIG. 54) inside the support substrate 2511. The third transparent electrode p and the second transparent electrode p are also connected to the transistors Tr2 (see FIG. 54) inside the support substrate 2511 through connection portions 2711b and 2731b.
[0469] [0469] In this way, the first to the third LED batteries are connected to each other, thus forming a circuit for activating the active matrix, as shown in FIG. 54.
[0470] [0470] Although FIG. 55 show a pixel having an electrical connection for activating the active matrix according to an exemplary mode, the inventive concepts are not limited to this and the circuit for the display device can be modified in several circuits for activating the active matrix in several ways .
[0471] [0471] In addition, the reflective electrode 2250, the second transparent electrode p 2350 and the third transparent electrode p 2450 of FIG. 46 are described as forming ohmic contact with the p-type semiconductor layer of each of the first 2230 LED batteries, the second 2330 LED battery and the third 2430 LED battery, and the 2290 ohmic electrode is described as forming ohmic contact with the type n semiconductor layer of the first 2230 LED stack, the type n semiconductor layer of each of the second 2330 LED stack and the third 2430 LED stack is not provided with a separate ohmic contact layer. Although there is less difficulty in propagating the current, even without the formation of a separate ohmic contact layer in the n-type semiconductor layer when the pixels are small in size of 200 µm or less, however, a transparent electrode layer can be arranged in the type n semiconductor layer of each of the LED cells to guarantee the current propagation according to some exemplary modalities.
[0472] [0472] Furthermore, although FIG. 46 show the coupling of the first to the third stack of LEDs 2230, 2330 and 2430 to each other by means of connection layers, the inventive concepts are not limited to this and the first to the third stack of LEDs 2230, 2330 and 2430 can be connected to another in several sequences and using several structures.
[0473] [0473] According to exemplary modalities, since it is possible to form a plurality of pixels at the wafer level using the 2000 light emitting diode stack for a display, the need for individual assembly of light emitting diodes can be avoided. In addition, the stack of light-emitting diodes according to exemplary modalities has the structure in which the first to the third batteries of LEDs 2230, 2330 and 2430 are stacked in the vertical direction and, therefore, an area for sub-pixels can be protected in a limited pixel area. In addition, the battery of light emitting diodes according to the exemplary modalities allows the light generated from the first 2230 LED battery, the second 2330 LED battery and the third 2430 LED battery to be emitted out of it, reducing thus the loss of light.
[0474] [0474] FIG. 56 is a schematic plan view of a display device according to an exemplary embodiment, and FIG. 57 is a schematic cross-sectional view of a LED pixel for a display in accordance with an exemplary embodiment.
[0475] [0475] Referring to FIG. 56 and FIG. 57, the display device includes a circuit board 3510 and a plurality of pixels 3000. Each of the pixels 3000 includes a substrate 3210 and first to the third subpixels R, G and B arranged on the substrate
[0476] [0476] The 3510 circuit board can include a passive circuit or an active circuit. The passive circuit can include, for example, data lines and scan lines. The active circuit can include, for example, a transistor and a capacitor. The 3510 circuit board may have a circuit on a surface or on it. Circuit board 3510 may include, for example, a glass substrate, a sapphire substrate, a Si substrate or a Ge substrate.
[0477] [0477] Substrate 3210 supports the first to third subpixels R, G and B. Substrate 3210 is continuous across the plurality of 3000 pixels and electrically connects subpixels R, G and B to circuit board 3510. For example, substrate 3210 can be a GaAs substrate.
[0478] [0478] The first subpixel R includes a first 3230 LED battery, the second subpixel G includes a second 3330 LED battery and the third subpixel B includes a third LED battery
[0479] [0479] The first 3230 LED battery, the second 3330 LED battery and the third 3430 LED battery are stacked to overlap in the vertical direction. Here, as shown in Fig. 57, the second 3330 LED battery can be arranged on a portion of the first 3230 LED battery. For example, the second 3330 LED battery can be arranged to one side on the first LED battery.
[0480] [0480] The R light generated from the first 3230 LED battery can be emitted through a region not covered by the second 3330 LED battery and the G light generated from the second 3330 LED battery can be emitted through a region not covered by the third 3430 LED battery. More particularly, the light generated from the first 3230 LED battery can be emitted to the outside without going through the second 3330 LED battery and the third 3430 LED battery, and the light generated at from the second 3330 LED battery it can be emitted to the outside without going through the third 3430 LED battery.
[0481] [0481] The region of the first 3230 LED battery through which R light is emitted, the region of the second 3330 LED battery through which G light is emitted, and the region of the third 3340 LED battery can have different areas and the intensity of the light emitted by each of the 3230, 3330 and 3430 LED cells can be adjusted by adjusting their areas.
[0482] [0482] However, inventive concepts are not limited to these. Alternatively, the light generated from the first 3230 LED battery can be emitted to the outside after passing through the second 3330 LED battery or after passing through the second 3330 LED battery and the third 3430 LED battery and the light generated from from the second 3330 LED battery it can be emitted to the outside after passing through the third 3430 LED battery.
[0483] [0483] Each of the first 3230 LED battery, the second 3330 LED battery and the 3430 LED battery can include a first conductivity type semiconductor layer (for example, type n), a second type semiconductor layer conductivity (for example, type p) and an active layer interposed between them. The active layer can have a multi-quantum well structure. The first to the third stack of 3230, 3330 and 3430 LEDs can include different active layers to emit light with different wavelengths. For example, the first 3230 LED battery can be an inorganic light emitting diode configured to emit red light, the second 3330 LED battery can be an inorganic light emitting diode configured to emit green light and the third 3430 LED battery can be be an inorganic light emitting diode configured to emit blue light. For this purpose, the first 3230 LED stack can include an AlGaInP based well layer, the second 3330 LED stack can include an AlGaInP or AlGaInN based well layer and the third 3430 LED stack can include a well layer based on AlGaInN. However, inventive concepts are not limited to these. The wavelengths of light generated from the first 3230 LED battery, the second 3330 LED battery and the third 3430 LED battery can be varied. For example, the first 3230 LED battery, the second 3330 LED battery and the third 3430 LED battery can emit green light, red light and blue light, respectively, or they can emit green light, blue light and red light, respectively.
[0484] [0484] In addition, a distributed Bragg reflector can be interposed between the 3210 substrate and the first 3230 LED stack to prevent the loss of light generated from the first 3230 LED stack through absorption by the 3210 substrate. For example, a distributed Bragg reflector formed by alternating stacking of semiconductor layers AlAs and AlGaAs one above the other can be interposed between them.
[0485] [0485] FIG. 58 is a schematic circuit diagram of a display device according to an exemplary embodiment.
[0486] [0486] Referring to FIG. 58, the display device, according to an exemplary embodiment, can be operated in an active matrix manner. As such, the circuit board can include an active circuit.
[0487] [0487] For example, the drive circuit can include at least two transistors Tr1, Tr2 and a capacitor. When a power source is connected to the selection lines Vrow1 to Vrow3 and the voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding LED. In addition, the corresponding capacitors are charged according to the values from Vdata1 to Vdata3. As the activation state of transistor Tr2 can be maintained by the charged voltage of the capacitor, the voltage of the capacitor can be maintained and applied to the light-emitting cells of LED1, LED3 and LED3, even when the power supply to Vrow1 is turned off. In addition, the electric current flowing in the light emitting diodes LED1 to LED3 can be changed depending on the values from Vdata1 to Vdata3. The electric current can be supplied continuously through Vdd and, therefore, the light can be emitted continuously.
[0488] [0488] Transistors Tr1, Tr2 and capacitor can be formed inside the support substrate 3510. Here, the light emitting diodes LED1 to LED3 can correspond to the first to third batteries of LEDs 3230, 3330 and 3430 stacked in one pixel, respectively. The anodes from the first to the third 3230, 3330 and 3430 LED batteries are connected to transistor Tr2 and their cathodes are connected to ground. The cathodes from the first to the third stack of LEDs 3230, 3330 and 3430, for example, can be commonly connected to ground.
[0489] [0489] Although FIG. 58 show the circuit for activating the active matrix according to an exemplary mode, other types of circuits can also be used. In addition, although the anodes of the light emitting diodes LED1 to LED3 are described as connected to the different transistors Tr2 and their cathodes are described as connected to ground, the anodes of the light emitting diodes can be commonly connected and the cathodes of the same be connected to different transistors in some exemplary modalities.
[0490] [0490] Although the active circuit for activating the active matrix is illustrated above, the inventive concepts are not limited to these, and the pixels, according to an exemplary modality, can be activated in a passive matrix manner. As such, circuit board 3510 can include data lines and scan lines arranged on it, and each of the subpixels can be connected to the data line and the scan line. In an exemplary embodiment, the anodes from the first to the third LED batteries 3230, 3330 and 3430 can be connected to different data lines and their cathodes can be commonly connected to a scan line. In other exemplary embodiments, the anodes from the first to the third LED batteries 3230, 3330 and 3430 can be connected to different scanning lines and the cathodes of them can be commonly connected to a data line.
[0491] [0491] In addition, each of the 3230, 3330 and 3430 LED batteries can be triggered by a pulse width modulation or by changing the magnitude of the electric current, thus controlling the brightness of each subpixel. In addition, the brightness can be adjusted by adjusting the areas of the first to the third 3230, 3330 and 3430 LED batteries and the areas of the 3230, 3330 and 3430 LED battery regions through which the R, G and B lights are emitted. For example, an LED battery that emits light with low visibility, for example, the first 3230 LED battery, has a larger area than the second 3330 LED battery or the third 3430 LED battery and, therefore, can emit light with greater intensity under the same current density. In addition, since the area of the second 3330 LED battery is larger than the area of the third 3430 LED battery, the second 3330 LED battery can emit light with a higher intensity under the same current density as the third battery 3430 LEDs. In this way, the light output can be adjusted based on the visibility of the light emitted from the first to the third 3230, 3330 and 3430 LED batteries, adjusting the areas of the first 3230 LED battery, the second 3330 LED battery and the third 3430 LED stack.
[0492] [0492] FIG. 59A and FIG. 59B are a top and bottom pixel view of a display device according to an exemplary embodiment, and FIG. 60A, FIG. 60B, FIG. 60C, and FIG. 60D are schematic cross-sectional views taken along lines A-A, B-B, C-C and D-D of FIG. 59A, respectively.
[0493] [0493] In the display device, the pixels are arranged on a 3510 circuit board (see FIG. 56) and each of the pixels includes a 3210 substrate and R, G and B subpixels. The 3210 substrate can be continuous along the plurality of pixels. Next, a one-pixel configuration, according to an exemplary mode, will be described.
[0494] [0494] Referring to FIG. 59AA, FIG. 59B, FIG. 60A, FIG. 60B, FIG. 60C, and FIG. 60D, the pixel includes a substrate 3210, a distributed Bragg reflector 3220, an insulating layer 3250, orifice paths 3270a, 3270b, 3270c, a first stack of LED 3230, a second stack of LED 3330, a second stack of LED 3330, a third 3430 LED battery, a first ohmic electrode 1 3290a, a first ohmic electrode 2 3290b, a second ohmic electrode 1 3390, a second ohmic electrode 2 3350, a third ohmic electrode 1 3490, a third ohmic electrode 2 3490 , a third ohmic electrode 2 3450, a first connection layer 3530, a second connection layer 3550, an upper insulation layer 3610, connectors 3710, 3720, 3730, a lower insulation layer 3750 and electrode pads 3770a, 3770b, 3770c, 3770d.
[0495] [0495] Each of the R, G and B subpixels includes 3230, 3330 and 3430 LED batteries and ohmic electrodes. In addition, the anodes from the first to the third subpixels R, G and B can be electrically connected to the electrode pads 3770a, 3770b and 3770c, respectively, and their cathodes can be electrically connected to the electrode pad 3770d, thus allowing the first to the third subpixels R, G and B to be triggered independently.
[0496] [0496] The 3210 substrate supports the 3230, 3330 and 3430 LED stacks. The 3210 substrate can be a growth substrate on which the AlGaInP-based semiconductor layers can be grown on top of it, for example, a GaAs substrate. In particular, substrate 3210 can be a semiconductor substrate exhibiting n-type conductivity.
[0497] [0497] The first 3230 LED stack includes a first semiconductor layer of conductivity type 3230a and a second semiconductor layer of conductivity type 3230b, the second stack of LED 3330 includes a first semiconductor layer of conductivity type 3330a and a second layer semiconductor of conductivity type 3330b, and the third LED stack 3430 includes a first semiconductor layer of conductivity type 3430a and a second semiconductor layer of conductivity type 3430b. An active layer can be interposed between the first semiconductor layer of conductivity type 3230a, 3330a or 3430a and the second semiconductor layer of conductivity type 3230b, 3330b or 3430b.
[0498] [0498] According to an exemplary embodiment, each of the first semiconductor layers of conductivity type 3230a, 3330a, 3430a can be a semiconductor layer of type n and each of the semiconductor layers of conductivity type 3230b, 3330b, 3430b can be a p-type semiconductor layer. A rough surface can be formed on an upper surface of each of the first semiconductor layers of conductivity type 3230a, 3330a, 3430a by texturing the surface. However, the inventive concepts are not limited to these and the first and second types of conductivity can be changed vice versa.
[0499] [0499] The first 3230 LED stack is arranged near the 3510 support substrate, the second 3330 LED stack is placed on the first 3230 LED stack and the third 3430 LED stack is placed on the second 3330 LED stack. The second 3330 LED stack is arranged somewhere in the first 3230 LED stack, so that the first 3230 LED stack partially overlaps the second 3330 LED stack. The third 3430 LED stack is somewhere in the second stack of LED 3330, so that the second battery of LED 3330 partially overlaps the third battery of LED 3430. Therefore, the light generated from the first battery of LED 3230 can be emitted to the outside without going through the second and third batteries of 3330 and 3430 LEDs. In addition, the light generated from the second 3330 LED battery can be emitted outdoors without going through the third 3430 LED battery.
[0500] [0500] The materials for the first 3230 LED battery, the second 3330 LED battery and the third 3430 LED battery are substantially the same as those described with reference to FIG. 57 and, therefore, detailed descriptions will be omitted to avoid redundancy.
[0501] [0501] The 3220 distributed Bragg reflector is interposed between the 3210 substrate and the first 3230 LED stack. The 3220 distributed Bragg reflector can include a semiconductor layer grown on the 3210 substrate. For example, the 3220 distributed Bragg reflector can be formed by alternately stacking layers of AlAs and layers of AlGaAs. The distributed Bragg reflector 3220 may include a semiconductor layer that electrically connects substrate 3210 to the first conductivity-type semiconductor layer 3230a of the first 3230 LED stack.
[0502] [0502] The through hole paths 3270a, 3270b, 3270c are formed through the substrate 3210. The through hole paths 3270a, 3270b, 3270c can be formed to pass through the first stack of LED 3230. The through hole paths passage 3270a, 3270b, 3270c can be formed of conductive pastes or by plating.
[0503] [0503] The insulating layer 3250 is disposed between the through hole paths 3270a, 3270b and 3270c and an inner wall of a through hole formed through the substrate 3210 and the first stack of LED 3230 to prevent short circuit between the first 3230 LED stack and the 3210 substrate.
[0504] [0504] The first 3290a ohmic electrode forms ohmic contact with the first 3230a conductivity type semiconductor layer of the first 3230 LED stack. The first 3290a ohmic electrode can be formed, for example, by Au-Te or Au-Ge alloys .
[0505] [0505] In order to form the first ohmic electrode 3290a, the second semiconductor layer of conductivity type 3230b and the active layer can be partially removed to expose the first semiconductor layer of conductivity type 3230a. The first 3290a ohmic electrode can be disposed away from the region where the second 3330 LED battery is located. In addition, the first ohmic electrode 1 3290 can include a pad region and an extension, and connector 3710 can be connected to the pad region of the first ohmic electrode 1 3290, as shown in FIG. 59A.
[0506] [0506] The first ohmic electrode 2 3290b forms ohmic contact with the second semiconductor layer of conductivity type 3230b from the first 3230 LED stack. As shown in Fig. 59A, the first ohmic electrode 2 3290b can be formed to partially surround the first ohmic electrode 1 3290a, in order to assist in the propagation of current. The first 3290b ohmic electrode may not include the extension. The first ohmic electrode 2 3290b can be formed from, for example, Au-Zn or Au-Be alloys. In addition, the first 3290b ohmic electrode may have a single layer or multilayer structure.
[0507] [0507] The first ohmic electrode 2 3290b can be connected to the through hole path 3270a, so that the through hole path 3270a can be electrically connected to the second semiconductor layer of conductivity type 3230b.
[0508] [0508] The second ohmic electrode 1 3390 forms ohmic contact with the first semiconductor layer of conductivity type 3330a of the second 3330 LED stack. The second ohmic electrode 1 3390 can also include a pad region and an extension. As shown in Fig. 59A, connector 3710 can electrically connect the second ohmic electrode 3390 to the first ohmic electrode 3290a. The second ohmic electrode 1 3390 can be placed in the part of the region where the third 3430 LED battery is located.
[0509] [0509] The second ohmic electrode 2 3350 forms ohmic contact with the second semiconductor layer of conductivity type 3330b of the second 3330 LED stack. The second ohmic electrode 2
[0510] [0510] The third ohmic electrode 1 3490 forms ohmic contact with the first semiconductor layer of conductivity type 3430a from the third 3430 LED stack. The third ohmic electrode 1 3490 can also include a pad region and an extension, and the 3710 connector can connect the third ohmic electrode 1 3490 to the first ohmic electrode 1 3290a, as shown in FIG. 59A.
[0511] [0511] The third ohmic electrode 2 3450 can form ohmic contact with the second semiconductor layer of conductivity type 3430b of the third 3430 LED stack. The third ohmic electrode 2 3450 can include a reflective layer 3450a and a barrier layer 3450b. The reflective layer 3450a reflects the light generated from the third 3430 LED stack to improve the luminous efficacy of the third 3430 LED stack. The 3450b barrier layer can act as a connection pad, which provides the 3450a reflective layer, and is connected to connector 3730. Although the third ohmic 3450 electrode is described as including a metal layer, the inventive concepts are not limited to these. Alternatively, the third ohmic electrode 2 3450 can be formed of a transparent conductive oxide, such as a conductive oxide semiconductor layer.
[0512] [0512] The first ohmic electrode 2 3290b, the second ohmic electrode 2 3350 and the third ohmic electrode 2 3450 can form ohmic contact with the p-type semiconductor layers of the corresponding LED cells to assist in current propagation and the first ohmic electrode 1 3290a, the second ohmic electrode 1 3390 and the third ohmic electrode 1 3490 can form ohmic contact with the n-type semiconductor layers of the corresponding LED cells to aid in current propagation.
[0513] [0513] The first 3530 connection layer couples the second 3330 LED battery to the first 3230 LED battery. As shown in the drawings, the second ohmic electrode 2 3350 can join with the first 3530 connection layer. The first connection layer 3530 can be a light transmitting layer or an opaque layer. The first 3530 bonding layer can be formed from an organic material or an inorganic material. Examples of the organic material can include SU8, poly (methyl methacrylate) (PMMA), polyimide, Parylene, benzocyclobutene (BCB) or others, and examples of the inorganic material can include Al2O3, SiO2, SiNx or others. The organic material layer can be bonded under high vacuum, and the inorganic material layer can be bonded under high vacuum after flattening the surface of the first bonding layer by, for example, mechanical chemical polishing, followed by adjusting the surface energy through plasma treatment. The first 3530 bonding layer can be formed by spin-on-glass or it can be a metal bonding layer formed by AuSn or the like. For the metal bonding layer, an insulation layer can be arranged on the first 3230 LED stack to protect the electrical insulation between the first 3230 LED stack and the metal bonding layer. In addition, a reflective layer can be further arranged between the first 3530 connection layer and the first 3230 LED battery to prevent the light generated from the first 3230 LED battery from entering the second 3330 LED battery.
[0514] [0514] The second layer of connection 3550 couples the second battery of LED 3330 to the third battery of LED 3430. The second layer of connection 3550 can be interposed between the second battery of LED 3330 and the third ohmic electrode 2 3450 to connect the second 3330 LED stack to the third ohmic 3450 electrode. The second 3550 bonding layer can be formed of substantially the same bonding material as the first 3530 bonding layer. In addition, an insulating layer and / or a reflective layer can also be arranged between the second 3330 LED battery and the second 3550 connection layer.
[0515] [0515] When the first 3530 bonding layer and the 3550 second bonding layer are formed of a light transmitting material, the second ohmic electrode 2 3350 and the third ohmic electrode 2 3450 are formed of a transparent oxide material, some light fractions generated from the first 3230 LED battery can be emitted through the second 3330 LED battery after passing through the first 3530 link layer and the second ohmic electrode 2 3350 and can also be emitted through the third 3430 LED battery after pass through the second 3550 connection layer and the third ohmic electrode 2 3450. In addition, some light fractions generated from the second 3330 LED battery can be emitted through the third 3430 LED battery after passing through the second 3550 connection layer and the third ohmic electrode 2 3450.
[0516] [0516] In this case, the light generated from the first 3230 LED battery must be prevented from being absorbed by the second 3330 LED battery while passing through the second 3330 LED battery. As such, the light generated from the first 3330 LED battery 3230 LED can have a smaller bandwidth than the second 3330 LED stack and therefore can have a longer wavelength than the light generated from the second 3330 LED stack.
[0517] [0517] Furthermore, to prevent the light generated from the second 3330 LED battery from being absorbed by the third 3430 LED battery while passing through the third 3430 LED battery, the light generated from the second 3330 LED battery may have a longer wavelength than the light generated from the third 3430 LED stack.
[0518] [0518] When the first 3530 link layer and the second 3550 link layer are formed of opaque materials, the reflective layers are interposed between the first 3230 LED stack and the first 3530 link layer and between the second 3330 LED stack and the second link layer 3550, respectively, to reflect light having been generated from the first 3230 LED stack and entering the first link 3530 and light having been generated from the second 3330 LED stack and entering the second layer connection 3550. The reflected light can be emitted through the first 3230 LED battery and the second 3330 LED battery.
[0519] [0519] The top insulating layer 3610 can cover the first to the third 3230, 3330 and 3430 LED batteries. In particular, the top insulating layer 3610 can cover the side surfaces of the second 3330 LED stack and the third LED stack. 3430, and can also cover the side surface of the first 3230 LED battery.
[0520] [0520] The top insulation layer 3610 has openings that expose the first to third through-hole paths 3270a, 3270b, 3270c and openings that expose the first semiconductor layer of conductivity type 3330a from the second 3330 LED stack, the first layer conductivity type semiconductor 3430a from the third 3430 LED stack, the second ohmic electrode 3350 and the third ohmic electrode 3450.
[0521] [0521] The upper insulation layer 3610 can be formed from any insulation material, for example, silicon oxide or silicon nitride, without being limited to these.
[0522] [0522] Connector 3710 electrically connects the first ohmic electrode 1 3290a, the second ohmic electrode 1 3390 and the third ohmic electrode 1 3490 to each other. The connector 3710 is formed in the upper insulation layer 3610 and is isolated from the second semiconductor layer of conductivity type 3430b of the third stack of LED 3430, the second semiconductor layer of conductivity type 3330b from the second stack of LED 3330 and the second semiconductor layer conductivity type 3230b from the first 3230 LED battery.
[0523] [0523] Connector 3710 can be formed of substantially the same material as the second ohmic electrode 1 3390 and the third ohmic electrode 1 3490 and therefore can be formed together with the second ohmic electrode 1 3390 and the third ohmic electrode 1 3490 Alternatively, connector 3710 can be formed from a conductive material other than the second ohmic electrode 1 3390 or the third ohmic electrode 1 3490 and therefore can be formed separately in a process different from the second ohmic electrode 1 3390 and / or the third electrode ohmic 1 3490.
[0524] [0524] Connector 3720 can electrically connect the second ohmic electrode 1 3350, for example, the barrier layer 3350b, to the second through hole 3270b. The 3730 connector electrically connects the third ohmic electrode 1, for example, the barrier layer 3450b, to the third through-hole path 3270c. The 3720 connector can be electrically isolated from the first 3230 LED stack by the top insulation layer
[0525] [0525] Connectors 3720, 3730 can be formed together by the same process. Connector 3720, 3730 can also be formed in conjunction with connector 3710. In addition, connectors 3720, 3730 can be formed from substantially the same material as the second ohmic electrode 3390 and the third ohmic electrode 3490, and can be formed together with the same. Alternatively, connectors 3720, 3730 can be formed from a conductive material other than the second ohmic electrode 1 3390 or the third ohmic electrode 1 3490 and therefore can be formed separately by a process different from the second ohmic electrode 1 3390 and / or the third ohmic electrode 1 3490.
[0526] [0526] The bottom insulating layer 3750 covers a lower surface of the substrate 3210. The lower insulating layer 3750 may include openings that expose the first to third through-hole paths 3270a, 3270b, 3270c on the underside of the substrate 3210 and also may include openings that expose the bottom surface of the 3210 substrate.
[0527] [0527] The electrode pads 3770a, 3770b, 3770c and 3770d are arranged on the bottom surface of the substrate 3210. The electrode pads 3770a, 3770b and 3770c are connected to the through hole paths 3270a, 3270b and 3270c through the layer openings insulation 3750 and the 3770d electrode pad is connected to the 3210 substrate.
[0528] [0528] The electrode pads 3770a, 3770b and 3770c are provided for each pixel to be electrically connected to the first to third LED batteries 3230, 3330 and 3430 of each pixel, respectively. Although the 3770d electrode pad can also be provided for each pixel, the 3210 substrate is continuously arranged over a plurality of pixels, which can avoid the need to provide the 3770d electrode pad for each pixel.
[0529] [0529] The electrode pads 3770a, 3770b, 3770c, 3770d are connected to the circuit board 3510, thus providing a display device.
[0530] [0530] In the following, a method of manufacturing the display device according to an exemplary embodiment will be described.
[0531] [0531] FIG. 61A to FIG. 61B are schematic plan views and cross-sectional views illustrating a method of manufacturing the display device according to an exemplary embodiment. Each of the cross-sectional views is taken along a line shown in each corresponding flat view.
[0532] [0532] Referring to FIG. 61A and 61B, a first 3230 LED stack is grown on a 3210 substrate. The 3210 substrate can be, for example, a GaAs substrate. The first 3230 LED stack consists of semiconductor layers based on AlGaInP and includes a first semiconductor layer of conductivity type 3230a, an active layer and a second semiconductor layer of conductivity type 3230b. A 3220 distributed Bragg reflector can be formed prior to the growth of the first 3230 LED stack. The 3220 distributed Bragg reflector can have a stack structure formed by repeatedly stacking, for example, layers of AlAs / AlGaAs.
[0533] [0533] Then, grooves are formed in the first 3230 LED stack and in the 3210 substrate through photolithography and engraving. The grooves can be formed to pass through the substrate 3210 or can be formed at a predetermined depth in the substrate 3210, as shown in FIG. 61B.
[0534] [0534] Then, an insulating layer 3250 is formed to cover the side walls of the grooves and the through hole paths 3270a, 3270b, 3270c are formed to fill the grooves. Through-hole paths 3270a, 3270b and 3270c can be formed, for example, by forming an insulating layer to cover the side walls of the grooves, filling the groove with a layer of conductive material or conductive pastes through the liner and removing the insulation and the conductive material layer of an upper surface of the first 3230 LED stack through mechanical chemical polishing.
[0535] [0535] Referring to FIG. 62A and FIG. 62B, a second 3330 LED battery and a second 3350 ohmic electrode can be coupled to the first 3230 LED battery through the first 3530 connection layer.
[0536] [0536] The second 3330 LED stack is grown on a second substrate and the second 3350 ohmic electrode is formed on the second 3330 LED stack. The second 3330 LED stack is formed by layers of semiconductors based on AlGaInP or the base of AlGaInN and can include a first semiconductor layer of conductivity type 3330a, an active layer and a second semiconductor layer of conductivity type 3330b. The second substrate can be a substrate on which the AlGaInP-based semiconductor layers can be grown on it, for example, a GaAs substrate or a substrate on which the AlGaInN-based semiconductor layers can be grown on it, for example, a sapphire. The composition ratio of Al, Ga and In for the second 3330 LED battery can be determined so that the second 3330 LED battery can emit green light. The second ohmic electrode 2 3350 forms ohmic contact with the second semiconductor layer of conductivity type 3330b, for example, a semiconductor layer of type p. The second ohmic electrode 2 3350 may include a reflective layer 3350a, which reflects the light generated from the second 3330 LED stack and a barrier layer 3350b.
[0537] [0537] The second ohmic electrode 2 3350 is arranged to face the first 3230 LED stack and is coupled to the first 3230 LED stack by the first 3530 link layer. After that, the second substrate is removed from the second 3330 LED stack to exposing the first semiconductor layer of conductivity type 3330a by chemical engraving or laser lifting. A rough surface can be formed on the first conductivity type semiconductor layer 3330a exposed by surface texturing.
[0538] [0538] According to an exemplary embodiment, an insulating layer and a reflecting layer can still be formed on the first 3230 LED stack before the first 3530 connection layer is formed.
[0539] [0539] Referring to FIG. 63A and FIG. 63B, a third 3430 LED battery and a third 3450 ohmic electrode 2 can be coupled to the second 3330 LED battery via the second 3550 connection layer.
[0540] [0540] The third 3430 LED stack is grown on a third substrate and the third 3450 ohmic electrode is formed on the third 3430 LED stack. The third 3430 LED stack is formed by semiconductor layers based on AlGaInN and can include a first semiconductor layer of conductivity type 3430a, an active layer and a second semiconductor layer of conductivity type 3430b. The third substrate is a substrate on which the GaN-based semiconductor layers can be grown on it and is different from the first 3210 substrate. The composition ratio of AlGaInN to the third 3430 LED stack can be determined so that the third stack of LED 3430 can emit blue light. The third ohmic electrode 2 3450 forms ohmic contact with the second semiconductor layer of conductivity type 3430b, for example, a semiconductor layer of type p. The third ohmic electrode 2 3450 may include a reflective layer 3450a, which reflects the light generated from the third 3430 LED stack and a barrier layer 3450b.
[0541] [0541] The third ohmic electrode 2 3450 is arranged to face the second battery of LED 3330 and is coupled to the second battery of LED 3330 by the second layer of connection 3550. After that, the third substrate is removed from the third battery of LED 3430 to expose the first semiconductor layer of conductivity type 3430a by chemical engraving or laser lifting. A rough surface can be formed in the first semiconductor layer 3430a of the conductivity type exposed by surface texturing.
[0542] [0542] According to an exemplary embodiment, an insulating layer and a reflecting layer can still be formed on the second 3330 LED stack before the second 3550 connection layer is formed.
[0543] [0543] Referring to FIG. 64A and FIG. 64B, in each of the pixel regions, the third 3430 LED stack is standardized to remove the third 3430 LED stack other than the third subpixel B. In a region of the third subpixel B, an indentation is formed in the third stack of LEDs. LED 3430 to expose the barrier layer 3450b through indentation.
[0544] [0544] Then, in regions other than the third subpixel B, the third ohmic electrode 2 3450 and the second 3550 bonding layer are removed to expose the second LED battery
[0545] [0545] In each pixel region, the second 3330 LED stack is standardized to remove the second 3330 LED stack in regions other than the second G sub-pixel. In the second G sub-pixel region, the second 3330 LED stack overlaps partially to the third 3430 LED battery.
[0546] [0546] When standardizing the second 3330 LED battery, the second ohmic electrode 2 3350 is exposed. The second 3330 LED stack can include an indentation, and the second ohmic electrode 2 3350, for example, the barrier layer 3350b, can be exposed through the indentation.
[0547] [0547] Subsequently, the second ohmic electrode 2 3350 and the first connection layer 3530 are removed to expose the first stack of LED 3230. As such, the second ohmic electrode 2 3350 is disposed close to the region of the second subpixel G. On the other hand In addition, the first to third through-hole paths 3270a, 3270b and 3270c are also exposed together with the first 3230 LED stack.
[0548] [0548] In each pixel region, the first semiconductor layer of conductivity type 3230a is exposed by standardizing the second semiconductor layer of conductivity type 3230b of the first stack of LED 3230. As shown in Fig. 64A, the first semiconductor layer of type conductivity 3230a can be exposed in an elongated form, without being limited to it.
[0549] [0549] In addition, the pixel regions are divided from each other, standardizing the first 3230 LED stack. As such, a region of the first subpixel R is defined. Here, the distributed Bragg reflector 3220 can also be divided. Alternatively, the distributed Bragg reflector 3220 can be arranged continuously over the plurality of pixels, instead of being divided. In addition, the first conductivity-like semiconductor layer 3230a can also be arranged continuously over the plurality of pixels.
[0550] [0550] Referring to FIG. 65A and FIG. 65B, a first ohmic electrode 1 3290a and a first ohmic electrode 2 3290b are formed in the first 3230 LED stack. The first ohmic electrode 1 3290a can be formed, for example, by Au-Te or Au-Ge alloys in the first layer conductivity type 3230a semiconductor exposed. The first ohmic electrode 2 3290b can be formed, for example, by Au-Be or Au-Zn alloys in the second semiconductor layer of conductivity type 3230b. The first ohmic electrode 2 3290b can be formed before the first ohmic electrode 1 3290a, or vice versa. The first ohmic electrode 2 3290b can be connected to the first through-hole path 3270a. On the other hand, the first ohmic electrode 1 3290a may include a pad region and an extension, which may extend from the pad region towards the first through-hole path 3270a.
[0551] [0551] For current propagation, the first ohmic electrode 2 3290b can be arranged to at least partially surround the first ohmic electrode 1 3290a. Although each of the first ohmic electrode 1 3290a and the first ohmic electrode 2 3290b are being illustrated as having an elongated shape in FIG. 65A, inventive concepts are not limited to these. Alternatively, each of the first ohmic electrode 1 3290a and first ohmic electrode 2 3290b may have a circular shape, for example.
[0552] [0552] Referring to FIG. 66A and FIG. 66B, a top insulation layer 3610 is formed to cover the first to third LED batteries 3230, 3330, 3430. The top insulation layer 3610 can cover the first ohmic electrode 1 3290a and the first ohmic electrode 2 3290b. The top insulation layer 3610 can also cover side surfaces of the first to third 3230, 3330 and 3430 LED batteries and a side surface of the distributed Bragg reflector 3220.
[0553] [0553] The upper insulating layer 3610 may have an opening 3610a that exposes the first ohmic electrode 1 3290a, openings 3610b, 3610c that expose barrier layers 3350b, 3450b, openings 3610d, 3610e that expose the second and third orifice paths passthrough 3270b, 3270c and openings 3610f, 3610g that expose the first semiconductor layers of conductivity type 3330a, 3430a of the second 3330 LED battery and the third 3430 LED battery.
[0554] [0554] Referring to FIG. 67A and FIG. 67B, a second ohmic electrode 1 3390, a third ohmic electrode 1 3490 and connectors 3710, 3720, 3730 are formed. The second ohmic electrode 1 3390 is formed at opening 3610f to form ohmic contact with the first semiconductor layer of conductivity type 3330a, and the third ohmic electrode 3490 is formed at opening 3610g to form ohmic contact with the first semiconductor layer of conductivity type 3430a.
[0555] [0555] Connector 3710 electrically connects the second ohmic electrode 1 3390 and the third ohmic electrode 1 3490 to the first ohmic electrode 1 3290a. Connector 3710 can be connected, for example, to the first ohmic electrode 1 3290a exposed in opening 3610a. The connector 3710 is formed in the upper insulating layer 3610 to be isolated from the second semiconductor layers of conductivity type 3230b, 3330b and 3430b.
[0556] [0556] Connector 3720 electrically connects the second ohmic electrode 2 3350 to the second through-hole 3270b and connector 3730 electrically connects the third ohmic electrode 2 3450 to the third through-hole 3270c. The 3720, 3730 connectors are arranged in the upper insulation layer 3610 to avoid short-circuiting the first to third 3230, 3330 and 3430 LED batteries.
[0557] [0557] The second ohmic electrode 1 3390, the third ohmic electrode 1 3490 and connectors 3710, 3720, 3730 can be formed from substantially the same material by the same process. However, inventive concepts are not limited to these. Alternatively, the second ohmic electrode 1 3390, the third ohmic electrode 1 3490 and connectors 3710, 3720, 3730 can be formed of different materials by different processes.
[0558] [0558] Then, with reference to FIG. 68A and FIG. 68B, a lower insulating layer 3750 is formed on a lower surface of the substrate 3210. The lower insulating layer 3750 has openings that expose the first through third through-hole paths 3270a, 3270b, 3270c and may also have openings that expose the bottom surface of the substrate 3210.
[0559] [0559] The electrode pads 3770a, 3770b, 3770c, 3770d are formed in the bottom insulating layer 3750. The electrode pads 3770a, 3770b, 3770c are connected to the first to third through-hole 3270a, 3270b, 3270c, respectively , and the 3770d electrode pad is connected to the 3210 substrate.
[0560] [0560] Consequently, the 3770a electrode pad is electrically connected to the second semiconductor layer of conductivity type 3230b of the first 3230 LED stack through the first through-hole path 3270a, the 3770b electrode pad is electrically connected to the second layer conductivity type 3330b semiconductor from the second 3330 LED stack through the second through-hole path 3270b and electrode pad 3770c is electrically connected to the second conductivity type 3430b semiconductor layer from the third 3430 LED stack via the third way through hole 3270c. The first semiconductor layers of conductivity type 3230a, 3330a, 3430a from the first to the third LED stack 3230, 3330, 3430 are commonly electrically connected to the 3770d electrode pad.
[0561] [0561] In this way, a display device, according to an exemplary embodiment, can be formed by connecting the electrode pads 3770a, 3770b, 3770c, 3770d of substrate 3210 to the circuit board 3510 shown in FIG. 56. As described above, circuit board 3510 can include an active circuit or a passive circuit, whereby the display device can be driven in either an active or passive matrix manner.
[0562] [0562] FIG. 69 is a cross-sectional view of a LED pixel for a display in accordance with an exemplary embodiment.
[0563] [0563] Referring to FIG. 69, the LED pixel 3001 of the display device, according to an exemplary embodiment, is generally similar to the LED pixel 3000 of the display device of FIG. 57, except that the second 3330 LED battery covers most of the first 3230 LED battery and the third 3430 LED battery covers most of the second 3330 LED battery. In this way, the light generated from the first R subpixel it is emitted to the outside after passing substantially through the second 3330 LED battery and the third 3430 LED battery, and the light generated from the second 3330 LED battery is emitted to the outside after substantially passing through the third 3430 LED battery.
[0564] [0564] The first 3230 LED battery can include an active layer with a narrower band gap than the second 3330 LED battery and the third 3430 LED battery to emit light with a wavelength longer than the second battery. LED 3330 and the third battery of LED 3430 and the second battery of LED 3330 can include an active layer with a bandwidth narrower than the third battery of LED 3430 to emit light with a wavelength longer than the third battery 3430 LED.
[0565] [0565] FIG. 70 is an enlarged one-pixel view of a display device according to an exemplary embodiment, and FIG. 71A and FIG. 71B are seen in cross section taken along lines G-G and H-H of FIG. 70, respectively.
[0566] [0566] Referring to FIG. 70, FIG. 71A, and FIG. 71B, the pixel, according to an exemplary embodiment, is generally similar to the pixel of FIG. 59, FIG. 60A, FIG. 60B and FIG. 60C, except that the second 3330 LED battery covers most of the first 3230 LED battery and the third 3430 LED battery covers most of the second 3330 LED battery. The first to third through-hole 3270a, 3270b , 3270c can be arranged outside the second 3330 LED battery and the third 3430 LED battery.
[0567] [0567] In addition, a portion of the first ohmic electrode 1 3290a and a portion of the second ohmic electrode 1 3390 can be arranged under the third battery of LED 3430. As such, the first ohmic electrode 1 3290a can be formed before the second battery 3330 LEDs can be coupled to the first 3230 LED battery and the second ohmic electrode 1 3390 can also be formed before the third 3430 LED battery is coupled to the second LED battery
[0568] [0568] In addition, the light generated from the first 3230 LED battery is emitted to the outside after substantially passing through the second 3330 LED battery and the third 3430 LED battery, and the light generated from the second LED battery 3330 is emitted to the outside after passing substantially through the third 3430 LED stack. Therefore, the first 3530 connection layer and the second 3550 connection layer are formed by light transmitting materials, and the second ohmic electrode 2 3350 and the third ohmic electrode 2 3450 are composed of transparent conductive layers.
[0569] [0569] On the other hand, as shown in FIGS. 71A and 71B, an indentation can be formed on the third 3430 LED stack to expose the third 3450 ohmic electrode and an indentation is formed continuously on the third 3430 LED stack and the second 3330 LED stack to expose the second 3333 ohmic electrode. The second ohmic electrode 2 3350 and the third ohmic electrode 2 3450 are electrically connected to the second via orifice 3270b and the third via via 3232c via connectors 3720, 3730, respectively.
[0570] [0570] In addition, the indentation can be formed on the third 3430 LED stack to expose the second ohmic electrode 1 3390 formed on the first conductive type 3330a semiconductor layer of the second 3330 LED stack, and the indentation can be formed continuously on the third 3430 LED battery and the second 3330 LED battery to expose the first 3290a ohmic electrode 1 formed in the first 3230a conductivity type semiconductor layer of the first 3230 LED cell. The 3710 connector can connect the first 3290a ohmic electrode and the second ohmic electrode 1 3390 to the third ohmic electrode 1
[0571] [0571] The first ohmic electrode 1 3290a and the second ohmic electrode 1 3390 are partially arranged under the third 3430 LED stack, but the inventive concepts are not limited to these. For example, the portions of the first ohmic electrode 1 3290a and the second ohmic electrode 1 3390 arranged under the third LED stack 3430 can be omitted. In addition, the second ohmic electrode 1 3390 can be omitted and the connector 3710 can form ohmic contact with the first semiconductor layer of conductivity type 3330a.
[0572] [0572] According to exemplary modalities, a plurality of pixels can be formed at the wafer level through the connection of the wafer and, thus, the process of individual assembly of light emitting diodes can be avoided or substantially reduced.
[0573] [0573] In addition, since through-hole paths 3270a, 3270b, 3270c are formed on substrate 3210 and used as current paths, substrate 3210 may not need to be removed. Therefore, a growth substrate used for the growth of the first 3230 LED stack can be used as the 3210 substrate without being removed from the first 3230 LED stack.
[0574] [0574] FIG. 72 is a schematic cross-sectional view of a stack of light emitting diode (LED) lights for a display according to an exemplary embodiment.
[0575] [0575] Referring to FIG. 72, the stack of light-emitting diodes 4000 for a display can include a support substrate 4051, a first battery of LED 4023, a second battery of LED 4033, a third battery of LED 4043, a reflective electrode 4025, an ohmic electrode 4026, a first insulating layer 4027, a second insulating layer 4028, an interconnecting line 4029, a second transparent electrode p 4035, a third transparent electrode p 4045, a first color filter 4037, a second color filter 4047, a second color filter 4047, layers of hydrophilic material 4052, 4054 and 4056, a first connection layer 4053 (a lower connection layer), a second connection layer 4055 (an intermediate connection layer) and a third connection layer 4057 (an upper bonding layer).
[0576] [0576] The support substrate 4051 supports semiconductor cells 4023, 4033 and 4043. The support substrate 4051 can have a circuit on its surface or inside, but is not limited to that. The support substrate 4051 can include, for example, a glass, a sapphire substrate, a Si substrate or a Ge substrate.
[0577] [0577] The first 4023 LED battery, the second 4033 LED battery and the third 4043 LED battery include the first semiconductor layers of conductivity type 4023a, 4033a and 4043a, the semiconductor layers of the second conductivity type 4023b, 4033b and 4043b and the active layers interposed between the first conductivity-type semiconductor layers and the second conductivity-type semiconductor layers. The active layer can have a multi-quantum well structure.
[0578] [0578] The first 4023 LED battery can be an inorganic LED that emits red light, the second 4033 LED battery can be an inorganic LED that emits green light and the third 4043 LED battery can be an inorganic LED that emits blue light . The first 4023 LED stack can include a GaInP based well layer, and the second 4033 LED stack and the third 4043 LED stack can include a GaInN based well layer. However, the inventive concepts are limited to them and, when the LED batteries include micro LEDs, the first 4023 LED battery can emit any red, green and blue light, and the second and third 4033 and 4043 LED batteries they can emit a different one of the red, green and blue lights without adversely affecting the operation or require color filters due to their small form factor.
[0579] [0579] The opposite surfaces of each 4023, 4033 or 4043 LED stack are a n-type semiconductor layer and a p-type semiconductor layer, respectively. The illustrated exemplary embodiment describes a case in which the first semiconductor layers of conductivity type 4023a, 4033a and 4043a of each of the first to third LED cells 4023, 4033 and 4043 are of type n and the second semiconductor layers of conductivity type 4023b , 4033b and 4043b are of the p type. A rough surface can be formed on the upper surfaces of the first to the third 4023, 4033 and 4043 LED batteries. However, the inventive concepts are not limited to them, and the type of semiconductor types on the upper and lower surfaces of each one of the LED batteries can be reversed.
[0580] [0580] The first 4023 LED stack is arranged to be adjacent to the support substrate 4051, the second 4033 LED stack is arranged on the first 4023 LED stack and the third 4043 LED stack is arranged on the second 4033 LED stack. Since the first 4023 LED battery emits light of a wavelength greater than the wavelengths of the second and third 4033 and 4043 LED batteries, the light generated in the first 4023 LED battery can be transmitted through the second and third batteries LED 4033 and 4043 and can be sent abroad. In addition, since the second 4033 LED battery emits light of a wavelength greater than the length of the third 4043 LED battery, the light generated in the second 4033 LED battery can be transmitted through the third 4043 LED battery and can be issued abroad.
[0581] [0581] The reflecting electrode 4025 is in ohmic contact with the second conductivity type semiconductor layer of the first 4023 LED stack and reflects the light generated in the first 4023 LED stack. For example, the reflecting electrode 4025 may include a layer in ohmic contact 4025a and a reflective layer 4025b.
[0582] [0582] The ohmic contact layer 4025a is partially in contact with the second conductivity-type semiconductor layer, that is, a p-type semiconductor layer. In order to prevent the absorption of light by the ohmic contact layer 4025a, an area in which the ohmic contact layer 4025a is in contact with the p-type semiconductor layer cannot exceed about 50% of a total area of the semiconductor layer of the like p. The reflective layer 4025b covers the ohmic contact layer 4025a and also covers the first insulation layer 4027. As illustrated, the reflective layer 4025b can substantially cover the entire ohmic contact layer 4025a, or a portion of the ohmic contact layer 4025a.
[0583] [0583] The reflective layer 4025b covers the first insulating layer 4027, so that an omnidirectional reflector can be formed by a stack of the first 4023 LED stack with a relatively high refractive index and the first insulating layer 4027 and the layer reflector 4025b with a relatively low refractive index. The reflective layer 4025b covers about 50% or more of the area of the first 4023 LED stack, preferably most of the region of the first 4023 LED stack, thus improving light efficiency.
[0584] [0584] The ohmic contact layer 4025a and the reflective layer 4025b can be formed by a metal layer containing gold (Au). The ohmic contact layer 4025a can be formed, for example, by an Au-Zn alloy or an Au-Be alloy. The reflective layer 4025b can be formed by a metal layer with high reflectivity in relation to the light generated in the first 4023 LED stack, for example, red light, such as aluminum (Al), silver (Ag) or gold (Au). In particular, Au can have relatively low reflectivity in relation to the light generated in the second 4033 LED battery and the third 4043 LED battery, for example, green light or blue light, and therefore can reduce light interference by absorbing the generated light. in the second and third LED batteries 4033 and 4043 and traveling towards the support substrate 4051.
[0585] [0585] The first insulating layer 4027 is disposed between the supporting substrate 4051 and the first LED stack 4023 and has an opening exposing the first LED stack 4023. The ohmic contact layer 4025a is connected to the first LED stack 4023 inside the opening of the first insulating layer 4027.
[0586] [0586] The ohmic electrode 4026 is in ohmic contact with the first semiconductor layer of conductivity type 4023a of the first layer of LED stack 4023. The ohmic electrode 4026 can be disposed in the first semiconductor layer of conductivity type 4023a partially exposed by removing the second semiconductor layer of conductivity type 4023b. Although FIG. 72 illustrates an ohmic electrode 4026, a plurality of ohmic electrodes 4026 are aligned in a plurality of regions on the support substrate 4051. The ohmic electrode 4026 can be formed, for example, by an Au-Te alloy or an Au-Ge alloy.
[0587] [0587] The second insulation layer 4028 is disposed between the support substrate 4051 and the reflective electrode 4025 to cover the reflective electrode 4025. The second insulation layer 4028 has an opening exposing the ohmic electrode 4026. The second insulation layer 4028 it can be formed from SiO2 or SOG.
[0588] [0588] The first interconnection line 4029 is arranged between the second insulation layer 4028 and the supporting substrate 4051, and is connected to the ohmic electro 4026 through the opening of the second insulation layer 4028. The interconnection line 4026 can connect a plurality of ohmic electrodes 4026 to each other on the support substrate 4051.
[0589] [0589] The second transparent electrode p 4035 is in ohmic contact with the second semiconductor layer of conductivity type 4033b of the second battery of LED 4033, that is, the semiconductor layer of type p. The second transparent electrode p 4035 can be formed by a metal layer or a layer of conductive oxide that is transparent to red light and green light.
[0590] [0590] The third transparent electrode p 4045 is in ohmic contact with the second semiconductor layer of conductivity type 4043b of the third battery of LED 4043, that is, the semiconductor layer of type p. The third transparent electrode p 4045 can be formed by a metal layer or a layer of conductive oxide that is transparent to red light, green light and blue light.
[0591] [0591] The reflective electrode 4025, the second transparent electrode p 4035 and the third transparent electrode p 4045 can be in ohmic contact with the type p semiconductor layer of each LED cell to assist in the dispersion of the current.
[0592] [0592] The first 4037 color filter can be disposed between the first 4023 LED stack and the second 4033 LED stack. In addition, the second 4047 color filter can be disposed between the second 4033 LED stack and the third stack 4043 LED. The first 4037 color filter transmits light generated in the first 4023 LED stack and reflects the light generated in the second LED stack.
[0593] [0593] According to some exemplary modalities, the first 4037 color filter can also reflect the light generated in the third 4043 LED battery. According to some exemplary modalities, when the LED batteries include micro LEDs, the color filters can omitted due to the small form factor of the micro LEDs.
[0594] [0594] The first and second color filters 4037 and 4047 can be, for example, a low-pass filter that passes through only a low-frequency region, that is, a long-wavelength region, a low-pass filter. band that passes only through a predetermined wavelength range or a band interrupt filter that blocks only the predetermined wavelength range. In particular, the first and second color filters 4037 and 4047 can be formed by alternating stacking of insulation layers with different refractive indices and can be formed by alternating stacking, for example, TiO2 and SiO2, Ta2O5 and SiO2, Nb2O5 and SiO2, HfO2 and SiO2 or ZrO2 and SiO2. In addition, the first and / or second 4037 and / or 4047 color filters may include a distributed Bragg reflector (DBR). The distributed Bragg reflector can be formed by alternately stacking layers of insulation with different refractive indices. In addition, an interrupted band of the distributed Bragg reflector can be controlled by adjusting a thickness of TiO2 and SiO2.
[0595] [0595] The first 4053 link layer couples the first 4023 LED stack to the 4051 support substrate. As shown, the 4029 interconnect line can be in contact with the first 4053 link layer. In addition, the 4029 interconnect line is arranged below some regions of the second insulation layer 4028, and a region of the second insulation layer 4028 that does not have the interconnect line 4029 may be in contact with the first connection layer 4053. The first connection layer 4053 can be transmissive to light or non-transmissive to light. In particular, a contrast of the display device can be improved by using a light-absorbing adhesive layer, such as black epoxy, as the first 4053 bonding layer.
[0596] [0596] The first 4053 bonding layer can be in direct contact with the 4051 support substrate, but as illustrated, the 4052 hydrophilic material layer can be arranged at an interface between the 4051 support substrate and the first 4053 bonding layer. The layer of hydrophilic material 4052 can alter a surface of the support substrate 4051 to be hydrophilic to improve adhesion of the first bonding layer 4053. As used herein, the bonding layer and the layer of hydrophilic material can collectively be referred to as a buffer layer.
[0597] [0597] The first bonding layer 4053 has a strong adhesion to the layer of hydrophilic material, while it has a weak adhesion to a layer of hydrophobic material. Therefore, peeling can occur in a portion where adhesion is poor. The layer of hydrophilic material 4052, according to an exemplary embodiment, can change a hydrophobic surface to be hydrophilic to improve the adhesion of the first bonding layer 4053, thus preventing peeling from occurring.
[0598] [0598] The layer of hydrophilic material 4052 can also be formed by depositing, for example, SiO2 or others on the surface of the support substrate 4051, and can also be formed by treating the surface of the support substrate 4051 with plasma to modify the surface. The modified layer on the surface increases the energy of the surface to change the hydrophobic property to hydrophilic property. In a case where the second insulation layer 4028 has hydrophobic property, the layer of hydrophilic material can also be disposed in the second layer of insulation 4028, and the first connection layer 4052 can be in contact with the layer of hydrophilic material in the second insulation layer 4028.
[0599] [0599] The second 4055 link layer couples the second 4033 LED stack to the first 4023 LED stack. The second 4055 link layer can be arranged between the first 4023 LED stack and the first 4037 color filter and can be in contact with the first 4037 color filter. The second link layer 4055 can transmit light generated in the first 4023 LED stack. A layer of hydrophilic material 4054 can be arranged at an interface between the first 4023 LED stack and the second layer of connection 4055. The first semiconductor layer of conductivity type 4023a of the first 4023 LED stack generally exhibits hydrophobic properties. Therefore, in a case where the second bonding layer 4055 is in direct contact with the first semiconductor layer of conductivity type 4023a, peeling is likely to occur at an interface between the second bonding layer 4055 and the first semiconductor layer of conductivity type 4023a.
[0600] [0600] The layer of hydrophilic material 4054, according to an exemplary embodiment, changes the surface of the first 4023 LED stack from having hydrophobic properties to having hydrophilic properties and thus improves the adhesion of the second 4055 bonding layer, thereby reducing or preventing peeling from occurring. The layer of hydrophilic material
[0601] [0601] A surface layer of the first color filter 4037 which is in contact with the second layer of connection 4055 may be a layer of hydrophilic material, for example, SiO2. In a case where the surface layer of the first color filter 4037 is not hydrophilic, the layer of hydrophilic material can be formed on the first color filter 4037 and the second bonding layer 4055 can be in contact with the layer of hydrophilic material .
[0602] [0602] The third layer of connection 4057 couples the third battery of LED 4043 to the second battery of LED 4033. The third layer of connection 4057 can be arranged between the second battery of LED 4033 and the second color filter 4047 and can be in contact with the second color filter 4047. The third connection layer 4057 transmits light generated in the first battery of LED 4023 and in the second battery of LED 4033. A layer of hydrophilic material 4056 can be arranged at an interface between the second battery of LED 4033 and the third 4057 link layer. The second 4033 LED stack may exhibit hydrophobic property and, as a result, in a case where the third 4057 link layer is in direct contact with the second 4033 LED stack, it is likely that stripping occurs at an interface between the third 4057 link layer and the second 4033 LED stack.
[0603] [0603] The layer of hydrophilic material 4056, according to an exemplary embodiment, changes the surface of the second 4033 LED stack from hydrophobic to hydrophilic property and therefore improves the adhesion of the third layer of connection 4057, thus preventing the occurrence peeling. The layer of hydrophilic material 4056 can be formed by depositing SiO2 or modifying the surface of the second 4033 LED plasma stack, as described above.
[0604] [0604] A surface layer of the second color filter 4047 which is in contact with the third layer of connection 4057 may be a layer of hydrophilic material, for example, SiO2. In a case where the surface layer of the second color filter 4047 is not hydrophilic, the layer of hydrophilic material can be formed in the second color filter 4047 and the third bonding layer 4057 can be in contact with the layer of hydrophilic material.
[0605] [0605] The first to third bonding layers 4053, 4055 and 4057 can be formed by light transmitting SOC, but are not limited to this, and other layers of transparent organic material or layers of transparent inorganic material can be used. Examples of the organic material layer can include SU8, poly (methylmethacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB) or others, and examples of the inorganic material layer can include Al2O3, SiO2, SiNx or others. The layers of organic material can be bonded at high vacuum and high pressure, and the layers of inorganic material can be bonded by planarizing a surface with, for example, a chemical mechanical polishing process, changing the energy of the surface using plasma or others and, then using the altered surface energy method.
[0606] [0606] FIGS. 73A to 73F are schematic cross-sectional views illustrating a method of manufacturing the 4000 LED light stack for a display according to the exemplary embodiment.
[0607] [0607] Referring to FIG. 73A, a first 4023 LED stack is grown for the first time on a first 4021 substrate. The first 4021 substrate can be, for example, a GaAs substrate. The first 4023 LED stack consists of semiconductor layers based on AlGaInP and includes a first semiconductor layer of conductivity type 4023a, an active layer and a second semiconductor layer of conductivity type 4023b.
[0608] [0608] Next, the second conductivity semiconductor layer 4023b is partially removed to expose the first conductivity semiconductor layer 4023a. Although FIG. 73A showing only one pixel region, the first semiconductor layer of conductivity type 4023a is partially exposed for each of the pixel regions.
[0609] [0609] A first 4027 insulation layer is formed on the first 4023 LED stack and is standardized to form openings. For example, SiO2 is formed in the first 4023 LED stack, a photoresistor is applied to it and a photoresistor pattern is formed through photolithography and development. Then, the first insulation layer 4027 in which the openings are formed can be formed by standardizing SiO2 using the photoresistor pattern as a recording mask. One of the openings in the first insulation layer 4027 can be arranged in the first semiconductor layer of conductivity type 4023a, and other openings can be arranged in the second semiconductor layer of conductivity type 4023b.
[0610] [0610] Thereafter, an ohmic contact layer 4025a and an ohmic electrode 4026 are formed in the openings of the first insulation layer 4027. The ohmic contact layer 4025a and the ohmic electrode 4026 can be formed using a lifting technique. The ohmic contact layer 4025a can be formed first and the ohmic electrode 4026 can be formed or vice versa.
[0611] [0611] After the formation of the ohmic contact layer 4025a, a reflective layer 4025b covering the ohmic contact layer 4025a and the first insulation layer 4027 is formed. The reflective layer 4025b can be formed using a lifting technique. The reflective layer 4025b can also cover a portion of the ohmic contact layer 4025a and can also substantially cover the entire ohmic contact layer 4025a, as illustrated. A reflective electrode 4025 is formed by the ohmic contact layer 4025a and the reflective layer 4025b.
[0612] [0612] The reflective electrode 4025 may be in ohmic contact with a p-type semiconductor layer of the first 4023 LED stack and may thus be referred to as a first reflective electrode of type p 4025. The reflective electrode 4025 is spaced from the ohmic electrode 4026 and therefore is electrically isolated from the first semiconductor layer of conductivity type 4023a.
[0613] [0613] A second insulation layer 4028 covering the reflective electrode 4025 and having an opening exposing the ohmic electrode 4026 is formed. The second insulation layer 4028 can be formed from, for example, SiO2 or SOG.
[0614] [0614] Then, an interconnection line 4029 is formed in the second insulation layer 4028. Interconnection line 4029 is connected to the ohmic electrode 4026 through the opening of the second insulation layer 4028 and therefore is electrically connected to the first semiconductor layer. 4023a of the conductivity type.
[0615] [0615] Although the interconnection line 4029 is illustrated in FIG. 73A as covering the entire surface of the second insulation layer 4028, the interconnect line 4029 can be partially arranged in the second insulation layer 4028, and an upper surface of the second insulation layer 4028 can be exposed around the interconnect line 4029.
[0616] [0616] Although the exemplary embodiment illustrated shows a pixel region, the first 4023 LED stack disposed on substrate 4021 can cover a plurality of pixel regions and interconnect line 4029 can normally be connected to ohmic electrodes 4026 formed in a plurality of regions. In addition, a plurality of interconnect lines 4029 can be formed on substrate 4021.
[0617] [0617] Referring to FIG. 73B, a second stack of LED 4033 is grown on a second substrate 4031 and a second transparent electrode p 4035 and a first color filter 4037 are formed on the second stack of LED 4033. The second stack of LED 4033 can include a first semiconductor layer conductivity type 4033a based on gallium nitride, a second semiconductor layer conductivity type 4033b and an active layer disposed between them, and the active layer can include a GaInN well layer. The second substrate 4031 is a substrate on which a semiconductor layer based on gallium nitride can be grown and is different from the first substrate 4021. A combination ratio of GaInN can be determined so that the second 4033 LED stack can emit green light . The second transparent electrode p 4035 is in ohmic contact with the second semiconductor layer of conductivity type 4033b.
[0618] [0618] The first color filter 4037 can be formed on the second transparent electrode p-4035, and since its details are substantially the same as those described with reference to FIG. 72, its detailed descriptions will be omitted to avoid redundancy.
[0619] [0619] Referring to FIG. 73C, a third 4043 LED stack is grown on a third 4041 substrate and a third transparent 4045 electrode and a second 4047 color filter are formed on the third 4043 LED stack. The third 4043 LED stack can include a first semiconductor layer Conductivity type 4043a based on gallium nitride, a second semiconductor layer of conductivity type 4043b and an active layer disposed between them, and the active layer can include a GaInN well layer. The third 4041 substrate is a substrate on which a semiconductor layer based on gallium nitride can be grown and is different from the first 4021 substrate. A combination ratio of GaInN can be determined so that the third 4043 LED stack emits blue light . The third transparent electrode 4045 is in ohmic contact with the second semiconductor layer of conductivity type 4043b.
[0620] [0620] Since the second color filter 4047 is substantially the same as that described with reference to FIG. 72, its detailed descriptions will be omitted to avoid redundancy.
[0621] [0621] Meanwhile, since the first 4023 LED battery, the second 4033 LED battery and the third 4043 LED battery are grown on different substrates, their order of formation is not particularly limited.
[0622] [0622] Referring to FIG. 73D, the first 4023 LED stack is then coupled to a support substrate 4051 through the first bonding layer 4053. The layers of bonding material can be arranged on the support substrate 4051 and the second insulation layer 4028 and can be connected together to form the first 4053 bonding layer. The interconnect line 4029 is arranged to face the supporting substrate
[0623] [0623] Meanwhile, in a case where a surface of the support substrate 4051 has hydrophobic property, a layer of hydrophilic material 4052 can be formed first on the support substrate 4051. The layer of hydrophilic material 4052 can also be formed by depositing a layer of material such as SiO2 on the surface of the support substrate 4051, or by treating the surface of the support substrate 4051 with plasma or the like to increase surface energy. The surface of the support substrate 4051 is modified by plasma treatment, and a modified surface layer with high surface energy can be formed on the surface of the support substrate 4051. The first bonding layer 4053 can be bonded to the layer of hydrophilic material 4052 , and the adhesion of the first bonding layer 4053 is thus improved.
[0624] [0624] The first 4021 substrate is removed from the first 4023 LED stack using a chemical etching technique. Therefore, the first conductivity type semiconductor layer of the first 4023 LED stack is exposed on the top surface. The exposed surface of the first semiconductor layer of conductivity type 4023a can be textured to increase the efficiency of light extraction, and a light extraction structure, such as a rough or other surface, can thus be formed on the surface of the first semiconductor layer of conductivity. conductivity type 4023a.
[0625] [0625] Referring to FIG. 73E, the second battery of LED 4033 is coupled to the first battery of LED 4023 through the second layer of connection 4055. The first color filter 4037 is arranged to face the first pile of LED 4023 and is connected to the second layer of connection 4055. The layers of bonding material are arranged in the first 4023 LED stack and the 4037 first color filter and are bonded together to form the second bonding layer
[0626] [0626] Meanwhile, before the second bonding layer 4055 is formed, a layer of hydrophilic material 4054 can be formed first on the first 4023 LED stack. The layer of hydrophilic material 4054 changes the surface of the first 4023 LED stack from have a hydrophobic property to a hydrophilic property and thus improves the adhesion of the second bonding layer 4055. The layer of hydrophilic material 4054 can also be formed by depositing a layer of material like SiO2 or treating the surface of the first 4023 LED stack with plasma or others to increase the energy of the surface. The surface of the first 4023 LED stack is modified by plasma treatment, and a modified surface layer with high surface energy can be formed on the surface of the first 4023 LED stack. The second 4055 bonding layer can be bonded to the material layer hydrophilic 4054, and the adhesion of the second bonding layer 4055 is thus improved.
[0627] [0627] The second 4031 substrate can be separated from the second 4033 LED stack using a technique such as a laser lift or a chemical lift. In addition, in order to improve light extraction, a rough surface can be formed on the exposed surface of the first semiconductor layer of conductivity type 4033a using surface texturing.
[0628] [0628] Referring to FIG. 73F, a layer of hydrophilic material 4056 can be formed on the second stack of LED 4033. The layer of hydrophilic material 4056 changes the surface of the second stack of LED 4033 to a hydrophilic property and,
[0629] [0629] Next, with reference to FIGS. 72 and 73C, the third battery of LED 4043 is coupled to the second battery of LED 4033 through the third layer of connection 4057. The second color filter 4047 is arranged to face the second battery of LED 4033 and is connected to the third layer of connection 4057. The layers of bonding material are arranged in the second LED stack 4033 (or in the hydrophilic material layer 4056) and in the third color filter 4047, and are bonded together to form the third bonding layer 4057.
[0630] [0630] The third 4041 substrate can be separated from the third 4043 LED stack using a technique such as a laser lift or a chemical lift. Therefore, as illustrated in FIG. 72, the LED stack for a display to which the first conductive layer 4043a of the third LED stack 4043 is exposed is provided. In addition, a rough surface can be formed on the exposed surface of the first semiconductor layer of conductivity type 4043a by texturing the surface.
[0631] [0631] A battery from the first to the third LED batteries 4023, 4033 and 4043 disposed on the support substrate 4051 is standardized in a pixel unit, and the standardized batteries are connected to each other using the interconnect lines, thus making it possible to provide a display device. In the following, a display device according to exemplary modalities will be described.
[0632] [0632] FIG. 74 is a schematic circuit diagram of a display device according to an exemplary embodiment, and FIG. 75 is a schematic plan view of a display device according to an exemplary embodiment.
[0633] [0633] Referring to FIGS. In the following, a display device according to exemplary modalities will be described.
[0634] [0634] For example, since the LED stack for a display is described with reference to FIG. 72 has a structure in which the first to the third LED cells 4023, 4033 and 4044 are stacked in a vertical direction, one pixel including three LEDs R, G and B. Here, a first LED R can match to the first 4023 LED battery, a second LED light G can correspond to the second 4033 LED battery and a third LED light B can correspond to the third 4043 LED battery.
[0635] [0635] In FIGS. 74 and 75, a pixel includes the first to third light emitting diodes R, G and B, and each light emitting diode corresponds to a subpixel. The anodes of the first to the third light-emitting diodes R, G and B are connected to a common line, for example, a data line and their cathodes are connected to different lines, for example, scanning lines. For a first pixel, as an example, the anodes from the first to the third light-emitting diodes R, G and B are commonly connected to a Vdata1 data line and their cathodes are connected to the Vscan1-1, Vscan1-2 scan lines , and Vscan1-3,
[0636] [0636] In addition, each of the light-emitting diodes R, G and B can be triggered by modulating the pulse width or changing the current intensity, thus making it possible to adjust the brightness of each subpixel.
[0637] [0637] Referring again to FIG. 75, a plurality of patterns are formed by patterning the stacks described with reference to FIG. 72, and the respective pixels are connected to the reflecting electrodes 4025 and to the interconnecting lines 4071, 4073 and 4075. As illustrated in FIG. 74, the reflective electrode 4025 can be used as a Vdata data line and the interconnect lines 4071, 4073 and 4075 can be formed as the scan lines. Here, interconnect line 4075 can be formed by interconnect line 4029. Reflective electrode 4025 can electrically connect the first semiconductor layers of conductivity type 4023a, 4033a and 4043a from the first to the third 4023, 4033 and 4043 LED batteries of the plurality of pixels to each other, and the interconnect line 4029 can be arranged as being substantially perpendicular to the reflective electrode 4025 to electrically connect the first semiconductor layers of conductivity type 4023a of the plurality of pixels to each other.
[0638] [0638] The pixels can be arranged in a matrix form, and the anodes of the light-emitting diodes R, G and B of each pixel are commonly connected to the reflective electrode 4025 and their cathodes are connected to the interconnection lines 4071, 4073 , and 4075 that are spaced from each other. Here, interconnect lines 4071, 4073 and 4075 can be used as Vscan scan lines.
[0639] [0639] FIG. 76 is an enlarged one-pixel plan view of the display device of FIG. 75, FIG. 77 is a schematic cross-sectional view taken along a line A-A of FIG. 76, and FIG. 78 is a schematic cross-sectional view taken along a line B-B of FIG. 76.
[0640] [0640] Referring back to FIGS. 75 to 78, at each pixel, a portion of the reflective electrode 4025, a portion of the second transparent electrode p 4035, a portion of the upper surface of the second LED battery 4033, a portion of the third transparent electrode p 4045 and the upper surface of the third 4043 LED stack are exposed to the outside.
[0641] [0641] The third 4043 LED stack may have a 4043r rough surface formed on its upper surface. The rough surface 4043r can also be formed on the entire upper surface of the third 4043 LED stack, or on a portion of the upper surface of the third 4043 LED stack.
[0642] [0642] A lower layer of insulation 4061 can cover a side surface of each pixel. The lower insulation layer 4061 can be formed of a light transmitting material, such as SiO2, and in this case, the lower insulation layer 4061 can also substantially cover the entire upper surface of the third 4043 LED stack. Alternatively, the layer 4061 bottom insulation, according to an exemplary embodiment, may include a light-reflecting layer or a light-absorbing layer to prevent light from traveling from the first to the third 4023, 4033 and 4043 LED batteries to the side surface and, in this case, the bottom insulation layer 4061 exposes at least partially the top surface of the third 4043 LED stack. The bottom insulation layer 4061 may include, for example, a distribution Bragg reflector or a metallic reflective layer, or a layer organic reflector in a transparent insulation layer, and can also include a light absorbing layer, such as black epoxy. The light-absorbing layer, such as black epoxy, can prevent light from being emitted to the outside of the pixels, thereby improving a contrast ratio between the pixels on the display device.
[0643] [0643] The bottom insulation layer 4061 can have an opening 4061a exposing the top surface of the third 4043 LED stack, an opening 4061b exposing the top surface of the second 4033 LED stack, an opening 4061c exposing the third transparent electrode p 4045, an opening 4061d and exposing the second transparent electrode p 4035 and an opening 4061e exposing the first reflective electrode of type p 4025. The top surface of the first LED battery 4023 cannot be exposed to the outside.
[0644] [0644] The interconnect line 4071 and the interconnect line 4073 can be formed on the support substrate 4051 in the vicinity of the first to the third LED cells 4023, 4033 and 4043, and can be arranged in the bottom insulation layer 4061 to be isolated of the first reflective electrode of type p 4025. A connector 4077ab connects the second transparent electrode p 4035 and the third transparent electrode 4045 to the reflective electrode 4025. Therefore, the anodes of the first 4023 LED battery, the second 4033 LED battery and the third 4043 LED stack are commonly connected to the reflector electrode
[0645] [0645] The interconnection line 4075 or 4029 can be arranged to be substantially perpendicular to the reflective electrode 4025 below the reflective electrode 4025 and is connected to the ohmic electrode 4026, thus being electrically connected to the first conductivity type semiconductor layer 4023a. The ohmic electrode 4026 is connected to the first semiconductor layer of conductivity type 4023a below the first LED stack
[0646] [0646] The 4071a connector connects the top surface of the third 4043 LED stack to the 4071 interconnect line and the 4073a connector connects the top surface of the second 4033 LED stack to the 4073 interconnect line.
[0647] [0647] An upper insulating layer 4081 can be arranged on the interconnecting lines 4071 and 4073 and the lower insulating layer 4061 to protect the interconnecting lines 4071, 4073 and 4075. The upper insulating layer 4081 can have openings that expose the interconnect lines 4071, 4073 and 4075, and a connecting wire and the like can be connected to it through the openings.
[0648] [0648] According to an exemplary modality, the anodes from the first to the third LED batteries 4023, 4033 and 4043 are commonly and electrically connected to the reflective electrode 4025, and their cathodes are electrically connected to the interconnection lines 4071, 4073 and 4075 , respectively. Therefore, the first to third LED batteries 4023, 4033 and 4043 can be driven independently. However, inventive concepts are not limited to them, and electrode and wiring connections can be modified in a number of ways.
[0649] [0649] FIGS. 79A to 79H are schematic views of the plan to describe a method for manufacturing a display device according to an exemplary embodiment. Next, a method for making the pixel of FIG. 76 will be described.
[0650] [0650] First, the stack of light-emitting diodes 4000, as described with reference to FIG. 72 is prepared.
[0651] [0651] Next, with reference to FIG. 79A, the rough surface 4043r can be formed on the top surface of the third 4043 LED stack. The rough surface 4043r can be formed to match each pixel region on the top surface of the third 4043 LED stack. The rough surface 4043r can be formed. by a chemical engraving technique, for example, by a photo-enhanced chemical engraving technique (PEC).
[0652] [0652] The rough surface 4043r can be partially formed within each pixel region in consideration of a region in which the third 4043 LED stack is to be engraved in the future. In particular, the rough surface 4043r can be formed so that the ohmic electrode 4026 is disposed outside the rough surface 4043r. However, the inventive concepts are limited to these, and the rough surface 4043r can also be formed over substantially the entire upper surface of the third 4043 LED stack.
[0653] [0653] Referring to FIG. 79B, a peripheral region of the third 4043 LED cell is then etched into each pixel region to expose the third transparent electrode p 4045. The third 4043 LED cell can have a substantially rectangular or square shape, as illustrated, but at least two depression parts can be formed along the edges. In addition, as illustrated, a part of the depression can be formed to be larger than another part of the depression.
[0654] [0654] Referring to FIG. 79C, the third exposed transparent electrode p 4045 is then removed, except for a portion of the third transparent electrode p 4045 exposed in a relatively large depression portion, to thereby expose the upper surface of the second 4033 LED stack. The upper surface of the second 4033 LED stack is exposed around the third 4043 LED stack and is also exposed in another part of the depression. A region in which the third transparent electrode p 4045 is exposed and a region in which the second battery of LED 4033 is exposed are formed in the relatively large depression part.
[0655] [0655] Referring to FIG. 79D, the second 4033 LED battery exposed in the remaining region is removed, except the second 4033 LED battery formed in a relatively small depression part to expose the second transparent electrode p 4035. The second transparent electrode p is exposed around the third battery of LED 4043 and the second transparent electrode p 4035 are also exposed in the relatively large depression part.
[0656] [0656] Referring to FIG. 79E, the second transparent electrode p 4035 exposed around the second battery of LED 4043 is then removed, except the second transparent electrode p 4035 exposed in the relatively large depression part, to thereby expose the upper surface of the first battery of LED 4023.
[0657] [0657] Referring to FIG. 79F, the first 4023 LED battery exposed around the third 4043 LED battery continues to be removed and the first insulation layer 4027 is removed to thereby expose the reflective electrode 4025. Consequently, the reflective electrode 4025 is exposed around the third 4043 LED stack. The exposed reflective electrode 4025 is standardized so that it is substantially elongated in the vertical direction to form a linear interconnect line. The standardized reflective electrode 4025 is arranged over the plurality of pixel regions in the vertical direction and is spaced from a neighboring pixel in the horizontal direction.
[0658] [0658] In the exemplary illustrated mode, it is described that the reflective electrode 4025 is modeled after the removal of the first battery of LED 4023, but the reflective electrode 4025 can also be formed in advance to have the standardized shape when the reflective electrode 4025 is formed in the substrate 4021. In this case, it is not necessary to standardize the reflective electrode 4025 after removing the first 4023 LED battery.
[0659] [0659] By standardizing the reflective electrode 4025, the second insulation layer 4028 can be exposed. The interconnect line 4029 is arranged to be perpendicular to the reflective electrode 4025 and is isolated from the reflective electrode 4025 by the second insulation layer 4028.
[0660] [0660] Referring to FIG. 79G, the bottom insulation layer 4061 (FIGS. 83 and 84) covering the pixels is then formed. The lower insulation layer 4061 covers the reflective electrode 4025 and covers the side surfaces of the first to the third LED batteries 4023, 4033 and 4043. In addition, the lower insulation layer 4061 can at least partially cover the upper surface of the third battery. LED 4043. In a case where the bottom insulation layer 4061 is a transparent layer like SiO2, the bottom insulation layer 4061 can also substantially cover the entire upper surface of the third 4043 LED stack. Alternatively, the bottom insulation layer 4061 may also include a reflective layer or a light absorbing layer, in which case the lower insulating layer 4061 exposes at least partially the upper surface of the third 4043 LED stack, so that the light is emitted to the outside.
[0661] [0661] The bottom insulating layer 4061 can have an opening 4061a exposing the third stack of LED 4043, an opening 4061b exposing the second stack of LED 4033, an opening 4061c exposing the third transparent electrode p 4045, an opening 4061d exposing the second transparent electrode p 4035 and an opening 4061e exposing the reflective electrode 4025. One or more openings 4061e that expose the reflective electrode 4025 can be formed.
[0662] [0662] Referring to FIG. 79H, interconnect lines 4071 and 4073 and connectors 4071a, 4073a and 77ab are then formed by a lifting technique. Interconnect lines 4071 and 4073 are isolated from reflective electrode 4025 by the bottom insulation layer 4061. Connector 4071a electrically connects the third 4043 LED stack to the 4071 interconnect line and connector 4073a connects the second 4033 LED stack to the interconnection 4073. Connector 77ab electrically connects the third transparent electrode p 4045 and the second transparent electrode p 4035 to the first reflective electrode of type p 4025.
[0663] [0663] The interconnection lines 4071 and 4073 can be arranged to be substantially perpendicular to the reflective electrode 4025 and can connect the plurality of pixels to each other.
[0664] [0664] Then, the upper insulating layer 4081 (FIGS. 83 and 84) covers the interconnection lines 4071 and 4073 and the connectors 4071a, 4073a and 4077ab. The upper insulating layer 4081 can also substantially cover the entire upper surface of the third 4043 LED stack. The upper insulating layer 4081 can be formed, for example, of silicon oxide film or silicon nitride film, and also can include a distribution Bragg reflector. In addition, the top insulating layer 4081 may include a transparent insulating film and a reflective metal layer, or an organic reflective layer of a multilayer structure on top of it to reflect light, or it may include a light absorbing layer , as a black-based epoxy to protect the light.
[0665] [0665] In a case where the upper insulating layer 4081 reflects or protects light, to emit light to the outside, it is necessary to expose at least partially the upper surface of the third 4043 LED stack. In the meantime, to allow a connection electrical on the outside, the upper insulation layer 4081 is partially removed to thereby partially expose the interconnect lines 4071, 4073 and 4075. In addition, the upper insulation layer 4081 can also be omitted.
[0666] [0666] As the upper insulating layer 4081 is formed, the pixel region illustrated in FIG. 76 is provided. In addition, as shown in FIG. 75, the plurality of pixels can be formed on the support substrate 4051, and these pixels can be connected to each other by the first reflective electrode of type p 4025 and by the interconnecting lines 4071, 4073 and 4075, and can be activated in a matrix passive.
[0667] [0667] In the exemplary example illustrated, the method for making the display device that can be actuated in the passive matrix manner is described, but the inventive concepts are not limited to that, and a display device including the stack of light emitting diodes light illustrated in FIG. 72 can be configured to be triggered in several ways.
[0668] [0668] For example, it is described that the interconnection lines
[0669] [0669] Meanwhile, FIG. 72, it is described that the reflective electrode 4025, the second transparent electrode p 4035 and the third transparent electrode p 4045 are in ohmic contact with the second semiconductor layers of conductivity type 4023b, 4033b and 4043b of the first LED stack 4023, the second LED battery 4033 and the third LED battery 4043, respectively, and the ohmic electrode 4026 is described in ohmic contact with the first semiconductor layer of conductivity type 4023a of the first LED battery 4023, but the ohmic contact layer does not. is supplied separately for the first semiconductor layers of conductivity type 4033a and 4033b of the second LED battery 4033 and the third LED battery
[0670] [0670] According to exemplary modalities, the plurality of pixels can be formed at a wafer level using the stack of light-emitting diodes 4000 for a display and, therefore, the individual assembly steps of the light-emitting diodes can be avoided . In addition, since the light emitting diode stack has a structure that the first to third 4023, 4033 and 4043 LED batteries are stacked vertically, an area of the subpixel can be protected within a limited pixel area. In addition, as the light generated in the first 4023 LED battery, the second 4033 LED battery and the third 4043 LED battery is transmitted through these LED batteries and emitted to the outside, it is possible to reduce light loss.
[0671] [0671] However, the inventive concepts are not limited to this, and light-emitting devices can also be provided in which the respective pixels are separated, and these light-emitting devices are individually mounted on a circuit board, thus making it possible to supply the display device.
[0672] [0672] Furthermore, it is described that the ohmic electrode 4026 is formed in the first semiconductor layer of conductivity type 4023a adjacent to the second semiconductor layer of conductivity type 4023b, but the ohmic electrode 4026 can also be formed on the surface of the first semiconductor layer conductivity type 4023a opposite the second semiconductor layer of conductivity type 4023b. In this case, the third 4043 LED battery and the second 4033 LED battery are standardized to expose the 4026 ohmic electrode and, instead of the 4029 interconnect line, a separate interconnect line is provided that connects the 4026 ohmic electrode to the circuit.
[0673] [0673] FIG. 80 is a cross-sectional view of a stacked light-emitting structure, according to an exemplary embodiment.
[0674] [0674] Referring to FIG. 80, a light-emitting stacked structure, according to an exemplary embodiment, includes a plurality of sequentially stacked epitaxial cells. A plurality of epitaxial cells are provided on substrate 5010.
[0675] [0675] Substrate 5010 is substantially plate-shaped having an upper surface and a lower surface.
[0676] [0676] A plurality of epitaxial cells can be mounted on the top surface of substrate 5010, and substrate 5010 can be supplied in a variety of ways. The substrate 5010 can be formed of an insulating material. Examples of the 5010 substrate material include glass, quartz, silicon, organic polymer, organic / inorganic composite or others. However, the material of substrate 5010 is not limited to it and is not particularly limited as long as it has an insulating property. In an exemplary embodiment, substrate 5010 may further include a wiring portion that can provide a light-emitting signal and a common voltage for the respective epitaxial cells. In an exemplary embodiment, in addition to the spinning part, substrate 5010 may also include a drive element including a thin film transistor, in which case the respective epitaxial cells can be driven in the type of active matrix. For this purpose, substrate 5010 can be supplied as a printed circuit board 5010 or as a composite substrate with a spinning part and / or a driving element formed of glass, silicon, quartz, organic polymer or organic / inorganic composite.
[0677] [0677] A plurality of epitaxial cells are stacked sequentially on an upper surface of the substrate 5010 and emit light respectively.
[0678] [0678] In an exemplary embodiment, two or more epitaxial cells can be provided, each emitting light of different wavelength bands from one another. That is, a plurality of epitaxial cells can be supplied, respectively, having different energy bands from each other. In an exemplary embodiment, the epitaxial cell on substrate 5010 is illustrated as being provided with three layers stacked sequentially, including the first to third epitaxial cells 5020, 5030 and 5040.
[0679] [0679] Each of the epitaxial cells can emit colored light from a visible light strip of several wavelength bands. The light emitted by the lowest epitaxial cell is colored light of the longest wavelength with the smallest energy range, and the wavelength of the colored light emitted is shorter in the order from the bottom to the top. The light emitted by the epitaxial cell at the top is colored light with the shortest wavelength and the largest energy range. For example, the first epitaxial cell 5020 can emit the first L1 color light, the second epitaxial cell 5030 can emit the second L2 color light and the third epitaxial cell 5040 can emit the third L3 color light. The first to the third color light L1, L2 and L3 corresponds to a light of a different color from each other, and the first to the third color light L1, L2 and L3 can be color light of different wavelength ranges from each others that have wavelengths that decrease sequentially. That is, the first to third color light L1, L2 and L3 can have different wavelength ranges from one another and the color light can be a shorter wavelength range of higher energy, in the order of first color light L1 to the third color of light L3. However, inventive concepts are not limited to this, and when the stacked light-emitting structure includes micro LEDs, the lower epitaxial cell can emit a color of light with any energy range, and the epitaxial cells disposed in it can emit a light color having different energy bands than the lower epitaxial cell due to the small form factor of the micro LEDs.
[0680] [0680] In the exemplary embodiment, the first L1 color light can be red light, the second L2 color light can be green light and the third L3 color light can be blue light, for example.
[0681] [0681] Each of the epitaxial cells emits light towards a frontal direction of the 5010 substrate. In particular, the light emitted by one epitaxial cell is passed through another epitaxial cell located in the light path and travels to the frontal direction. The front direction can correspond to a direction along which the first to third 5020, 5030 and 5040 epitaxial cells are stacked.
[0682] [0682] From now on, in addition to the front and rear directions mentioned above, the "front" direction of the 5010 substrate will be called the "top" direction and the "rear" direction of the 5010 substrate will be called the "bottom" direction. Obviously, the terms "upper" or "lower" refer to relative directions, which may vary according to the location and direction of the stacked light-emitting structure.
[0683] [0683] Each of the epitaxial cells emits light in the upper direction, and each of the epitaxial cells transmits most of the light emitted by the underlying epitaxial cells. In particular, the light emitted from the first epitaxial cell 5020 passes through the second epitaxial cell 5030 and the third epitaxial cell 5040 and travels to the front direction, and the light emitted from the second epitaxial cell 5030 passes through the third epitaxial cell 5030 and travels for the front direction. To this end, at least some, or desirably, all epitaxial cells other than the lower epitaxial cell may include an optically transmitting material. As used herein, the material being "optically transmitting" includes not only a transparent material that transmits all light, but also a material that transmits light with a predetermined wavelength or transmits a portion of light with a predetermined wavelength. In an exemplary embodiment, each epitaxial cell can transmit about 60% or more of the light emitted from the epitaxial cell disposed in it, or about 80% or more in another exemplary mode, or about 90% or more in still another exemplary modality.
[0684] [0684] In the stacked light-emitting structure according to an exemplary embodiment, the signal lines for applying emitting signals to the respective epitaxial cells are connected independently and, therefore, the respective epitaxial cells can be activated independently and the stacked light-emitting structure it can implement several colors according to whether the light is emitted from each of the epitaxial cells. In addition, epitaxial cells for emitting light of different wavelengths are superimposed vertically on top of each other and therefore can be formed in a narrow area.
[0685] [0685] FIGS. 81A and 81B are seen in cross-section illustrating a stacked light-emitting structure according to an exemplary embodiment.
[0686] [0686] Referring to FIG. 81A, in a stacked light-emitting structure according to an exemplary embodiment, each of the first to third epitaxial cells 5020, 5030 and 5040 can be provided on a 5010 substrate via an adhesive layer or a buffer layer interposed between them.
[0687] [0687] Adhesive layer 5061 adheres to substrate 5010 and the first epitaxial stack 5020 to substrate 5010. Adhesive layer 5061 can include a conductive or non-conductive material. The adhesive layer 5061 can have conductivity in some areas, when it needs to be electrically connected to the substrate 5010 provided below. The adhesive layer 5061 can include a transparent or opaque material. In an exemplary embodiment, when substrate 5010 is provided with an opaque material and has a spinning part or the like formed therein, the adhesive layer 5061 may include an opaque material, for example, a light-absorbing material. For the light-absorbing material that forms the 5061 adhesive layer, several polymeric adhesives can be used, including, for example, an epoxy-based polymeric adhesive.
[0688] [0688] The buffer layer acts as a component to adhere two layers adjacent to each other, while also serving to relieve stress or impact between two adjacent layers. The buffer layer is provided between two adjacent epitaxial cells to adhere the two adjacent epitaxial cells together, while also serving to relieve stress or impact that can affect the two adjacent epitaxial cells.
[0689] [0689] The buffer layer includes the first and second layers 5063 and 5065. The first buffer layer 5063 can be provided between the first and second epitaxial cells 5020 and 5030, and a second buffer layer 5065 can be provided between the second and the third epitaxial cells 5030 and 5040.
[0690] [0690] The buffer layer includes a material capable of relieving stress or impact, for example, a material which is capable of absorbing stress or impact when there is stress or impact on the outside. The buffer layer may have a certain elasticity for this purpose. The buffer layer can also include a material having an adhesive force. In addition, the first and second buffer layers 5063 and 5065 can include a non-conductive material and an optically transmitting material. For example, an optically clear adhesive can be used for the first and second layers of buffer 5063 and 5065.
[0691] [0691] The material to form the first and second layers of buffer 5063 and 5065 is not particularly limited as long as it is optically transparent and is able to cushion stress or impact by connecting each of the epitaxial cells in a stable manner. For example, the first and second layers of buffer 5063 and 5065 can be formed from an organic material, including an epoxy-based polymer, such as SU-8, various strengths, parylene, poly (methyl methacrylate) (PMMA), benzocyclocyclobutene (BCB), spin-on-glass (SOG), or others, and inorganic material, such as silicon oxide, aluminum oxide or similar. If necessary, a conductive oxide can also be used as a buffer layer, in which case the conductive oxide must be isolated from other components. When an organic material is used as a buffer layer, the organic material can be applied to the adhesive surface and then glued at a high temperature and high pressure in a vacuum state. When an inorganic material is used as a buffer layer, the inorganic material can be deposited on the adhesive surface and then planarized by chemical-mechanical planarization (CMP) or similar, after which the surface is subjected to plasma treatment and then bonded under high vacuum.
[0692] [0692] Referring to FIG. 81B, each of the first and second layers of buffer 5063 and 5065 can include an adhesion enhancement layer 5063a or 5065a to adhere two epitaxial cells adjacent to each other and a shock absorbing layer 5063b or 5065b to relieve stress or impact between the two adjacent epitaxial cells.
[0693] [0693] The shock-absorbing layer 5063b and 5065b between two adjacent epitaxial cells plays a role in absorbing stress or impact when at least one of the two adjacent epitaxial cells is exposed to stress or impact.
[0694] [0694] The material that forms the shock-absorbing layer 5063b and 5065b may include, but is not limited to, silicon oxide, silicon nitride, aluminum oxide or others. In an exemplary embodiment, the shock-absorbing layer 5063b and 5065b can include silicon oxide.
[0695] [0695] In an exemplary embodiment, in addition to voltage or impact absorption, the shock absorption layer 5063b and 5065b may have a predetermined adhesion force to adhere to two adjacent epitaxial cells. In particular, the shock-absorbing layer 5063b and 5065b can include a material with surface energy similar to or equivalent to the surface energy of the epitaxial cell to facilitate adhesion to the epitaxial cell. For example, when the surface of the epitaxial cell is hydrophilicized through plasma or other treatment, a hydrophilic material, such as silicon oxide, can be used as the shock absorbing layer in order to improve adhesion to the hydrophilic epitaxial cell.
[0696] [0696] Layer 5063a or 5065a to improve adhesion serves to firmly adhere two adjacent epitaxial cells. Examples of the material to form the 5063a or 5065a layer to improve adhesion include, but are not limited to, epoxy based polymers such as SOG, SU-8, various strengths, parylene,
[0697] [0697] In an exemplary embodiment, the first buffer layer 5063 may include a first layer 5063a for improving adhesion and a first layer 5063b of shock absorption, and the second layer 5065b of damping and the second layer of buffer 5065b may include a second adhesion enhancing layer 5065a and a second shock absorbing layer 5065b. In an exemplary embodiment, each adhesion enhancement layer and the shock absorption layer can be provided as a layer, but are not limited to it, and in another exemplary embodiment, each adhesion enhancement layer and the absorption layer. shock can be provided as a plurality of layers.
[0698] [0698] In an exemplary embodiment, the stacking order of the adhesion improvement layer and the shock absorption layer can be changed in several ways. For example, the shock absorbing layer can be stacked on the adhesion enhancement layer or, conversely, the adhesion improvement layer can be stacked on the shock absorbing layer. In addition, the stacking order of the adhesion enhancing layer and the shock absorbing layer in the first buffer layer 5063 and in the second buffer layer 5065 may be different. For example, in the first buffer layer 5063, the first shock-absorbing layer 5063b and the first adhesion enhancement layer 5063a can be stacked sequentially, while in the second buffer layer 5065, the first adhesion enhancement layer 5065a and the second layer shock absorbers 5065b can be stacked sequentially. FIG. 81B shows an exemplary embodiment in which the first shock-absorbing layer 5063b is stacked in the first adhesion enhancement layer 5063a in the first buffer layer 5063, and the second shock-absorbing layer 5065b is stacked in the second shock-absorbing layer 5065a in the second layer of buffer 5065.
[0699] [0699] In an exemplary embodiment, the thicknesses of the first buffer layer 5063 and the second buffer layer 5065 can be substantially the same or different from each other. The thickness of the first buffer layer 5063 and the second buffer layer 5065 can be determined in consideration of the amount of impact on the epitaxial cells in the process of stacking the epitaxial cells. In an exemplary embodiment, the thickness of the first buffer layer 5063 may be greater than the thickness of the second buffer layer 5065. In particular, the thickness of the first shock-absorbing layer 5063b in the first layer of buffer 5063 may be greater than the thickness of the second shock absorber layer 5065b in the second layer of buffer 5065.
[0700] [0700] The stacked light-emitting structure, according to an exemplary embodiment, can be manufactured through a process in which the first to third epitaxial cells 5020, 5030 and 5040 are stacked sequentially and, consequently, the second epitaxial cell 5030 is stacked after the first epitaxial cell 5020 is stacked and the third epitaxial cell 5040 is stacked after the first and second epitaxial cells 5020 and 5030 are stacked. Therefore, the amount of voltage or impact that can be applied to the first 5020 epitaxial cell during a process is greater than the amount of voltage or impact that can be applied to the second 5030 epitaxial cell and at an increased frequency. In particular, since the second epitaxial cell 5030 is stacked in a state where the cell is shallow in thickness, the second epitaxial cell 5030 is subjected to a greater amount of voltage or impact than the voltage or impact exerted on the third cell epitaxial 5040 which is stacked on the underlying pile of relatively greater thickness. In an exemplary embodiment, the thickness of the first buffer layer 5063 is greater than the thickness of the second buffer layer 5065 to compensate for the voltage or impact difference mentioned above.
[0701] [0701] FIG. 82 is a cross-sectional view of a stacked light-emitting structure, according to an exemplary embodiment.
[0702] [0702] Referring to FIG. 82, each of the first to third epitaxial cells 5020, 5030 and 5040 can be provided on the substrate 5010 through the adhesive layer 5061 and the first and second buffer layers 5063 and 5065 interposed between them.
[0703] [0703] Each of the first to third epitaxial cells 5020, 5030 and 5040 includes semiconductor layers of type p 5025, 5035 and 5045, active layers 5023, 5033 and 5043 and semiconductor layers of type n 5021, 5031 and 5041, which are arranged sequentially.
[0704] [0704] The p-type semiconductor layer 5025, the active layer 5023 and the n-type semiconductor layer 5021 of the first epitaxial cell 5020 may include a semiconductor material that emits red light.
[0705] [0705] Examples of a semiconductor material that emits red light may include aluminum and gallium arsenide (AlGaAs), gallium arsenide phosphate (GaAsP), aluminum and indium and gallium phosphide (AlGaInP), gallium phosphide (GaP) or others. However, the semiconductor material that emits red light is not limited to this and several other materials can be used.
[0706] [0706] A first p 5025p contact electrode can be provided under the p 5025 semiconductor layer of the first 5020 epitaxial cell. The first p 5025p contact electrode of the first 5020 epitaxial cell can be a single layer or a multilayer metal. For example, the first 5025p type p contact electrode can include various materials, including metals such as Al, Ti, Cr, Ni, Au, Ag, Ti, Sn, Ni, Cr, W, Cu or others or their alloys. The first contact electrode of type p 5025p can include metal with high reflectivity and, therefore, since the first contact electrode of type p 5025p is formed of metal with high reflectivity, it is possible to increase the efficiency of light emission emitted by first 5020 epitaxial cell in the upper direction.
[0707] [0707] A first n-type contact electrode 5021n can be provided in an upper portion of the n-type semiconductor layer of the first 5020 epitaxial cell. The first n-type contact electrode 5021n of the first 5020 epitaxial cell can be a single layer or a multilayer metal. For example, the first n 5021n type contact electrode can be formed from various materials, including metals such as Al, Ti, Cr, Ni, Au, Ag, Ti, Sn, Ni, Cr, W, Cu or others or alloys of themselves. However, the material of the first contact electrode of type n 5021n is not limited to those mentioned above and, therefore, other conductive materials can be used.
[0708] [0708] The second epitaxial cell 5030 includes a semiconductor layer of type n 5031, an active layer 5033 and a semiconductor layer of type p 5035, which are arranged sequentially. The semiconductor layer type 5031, the active layer 5033 and the semiconductor layer type p 5035 can include a semiconductor material that emits green light. Examples of materials for emitting green light include gallium nitride (AlGaInP) and aluminum and gallium phosphide (GaP), aluminum and indium and gallium phosphide (AlGaInP), and aluminum and gallium phosphide (AlGaP). However, the semiconductor material that emits the green light is not limited to these and several other materials can be used.
[0709] [0709] A second p 5035p contact electrode is provided under the p 5035 semiconductor layer of the second 5030 epitaxial cell. The second p 5035p contact electrode is provided between the first 5020 epitaxial cell and the second epitaxial cell 5030, or specifically, between the first buffer layer 5063 and the second epitaxial cell 5030.
[0710] [0710] Each of the second contact electrodes of type p 5035p can include a transparent conductive oxide (TCO). The transparent conductive oxide can include tin oxide (SnO), indium oxide (InO2), zinc oxide (ZnO), indium and tin oxide (ITO), indium and tin oxide (ITZO) or others. The transparent conductive compound can be deposited by chemical vapor deposition (CVD), physical vapor deposition (PVD), such as an evaporator, a spray or others. The second contact electrode of type p 5035p can be supplied with a thickness sufficient to serve as an engraving stopper in the manufacturing process to be described below, for example, with a thickness of about 5001 angstroms at about 2 micrometers, at insofar as transparency is satisfied.
[0711] [0711] The third epitaxial cell 5040 includes a semiconductor layer of type p 5045, an active layer 5043 and a semiconductor layer of type n 5041, which are arranged sequentially. The semiconductor layer type p 5045, the active layer 5043 and the semiconductor layer type n 5041 can include a semiconductor material that emits blue light. Examples of materials that emit blue light may include gallium nitride (GaN), indium and gallium nitride (InGaN), zinc selenide (ZnSe) or others. However, the semiconductor material that emits blue light is not limited to these and several other materials can be used.
[0712] [0712] A third type 5050p contact electrode pad is provided under the type 5045 semiconductor layer of the third 5040 epitaxial cell. The third type 5050p contact electrode pad is provided between the second 5030 epitaxial cell and the third epitaxial cell 5040, or specifically, between the second buffer layer 5065 and the third epitaxial cell 5040.
[0713] [0713] The second p type contact electrode 5035p and the third p type contact electrode pad 5045p between the p type semiconductor layer 5035 of the second epitaxial cell 5030 and the p type semiconductor layer 5045 of the third epitaxial cell 5040 are electrodes shared by the second epitaxial cell 5030 and the third epitaxial cell 5040.
[0714] [0714] Since the second p 5035p contact electrode and the third p 5045p contact electrode pad are at least partially in contact with each other and physically and electrically connected to each other, when a signal is applied to at least a portion of the second type p 5035p contact electrode or the third type p 5045p contact electrode pad, the same signal can be applied to the type p 5035 semiconductor layer of the second epitaxial cell 5030 and the semiconductor layer type p 5045 of the third epitaxial cell 5040 at the same time. For example, when a common voltage is applied to one of the second p type contact electrodes 5035p and to the third p type contact electrode pad 5045p, the common voltage is applied to the p type semiconductor layers of each of the second and third epitaxial cells 5030 and 5040 through the second contact electrode of type p 5035p and the third contact electrode of type p 5045p.
[0715] [0715] In the exemplary example illustrated, although semiconductor layers of type 5021, 5031 and 5041 and semiconductor layers of type p 5025, 5035 and 5045 of the first to third epitaxial cells 5020, 5030 and 5040 are shown as a single layer, these layers can be multilayered and can also include superstructure layers. In addition, active layers 5023, 5033 and 5043 of the first to third epitaxial cells 5020, 5030 and 5040 can include a single quantum well structure or a multi-quantum well structure.
[0716] [0716] In an exemplary embodiment, the second and third contact electrodes of the type p 5035p and 5045p, which are shared electrodes, substantially cover the second and third epitaxial cells 5030 and 5040. The second and third contact electrodes of the type p 5035p and 5045p can include a transparent conductive material to transmit light from the epitaxial cell below. For example, each of the second and third contact electrodes of the type p 5035p and 5045p may include a transparent conductive oxide (TCO). The transparent conductive oxide can include tin oxide (SnO), indium oxide (InO2), zinc oxide (ZnO), indium and tin oxide (ITO), indium and tin oxide (ITZO) or others. The transparent conductive compound can be deposited by chemical vapor deposition (CVD), physical vapor deposition (PVD), such as an evaporator, a spray or others. The second and third contact electrodes of the type p 5035p and 5045p can be supplied with a thickness sufficient to serve as an engraving stopper in the manufacturing process to be described below, for example, with a thickness of about 5001 angstroms at about 2 micrometers to the extent that the transparency is satisfied.
[0717] [0717] In an exemplary mode, common lines can be connected to the first to third contact electrodes of the type p 5025p, 5035p and 5045p. In this case, the common line is a line to which the common voltage is applied. In addition, the light emitting signal lines can be connected to layers 5021, 5031 and 5041 of type n semiconductors of the first to third epitaxial cells 5020, 5030 and 5040, respectively. A common SC voltage is applied to the first p 5025p contact electrode, the second p 5035p contact electrode and the third p 5045p contact electrode pad via the common line, and the light emitting signal is applied to the type n semiconductor layer 5021 of the first epitaxial cell 5020, the type n semiconductor layer 5031 of the second epitaxial cell 5030 and the type n semiconductor layer 5041 of the third epitaxial cell 5040 through the light emitting signal line, thus controlling the light emission from the first to the third epitaxial cells 5020, 5030 and 5040. The light emitting signal includes the first to the third light emitting signal SR, SG and SB, corresponding to the first to the third epitaxial cells 5020, 5030 and 5040, respectively. In an exemplary embodiment, the first light emitting signal SR can be a signal corresponding to red light, the second light emitting signal SG can be a signal corresponding to green light and the third light emitting signal SB can be a signal corresponding to a blue light emission.
[0718] [0718] In the exemplary illustrated mode described above, it is described that a common voltage is applied to layers 5025, 5035 and 5045 of type p semiconductors of the first to third epitaxial cells 5020, 5030 and 5040, and the light emitting signal is applied to semiconductor layers of type n 5021, 5031 and 5041 from the first to the third epitaxial cell 5020, 5030 and 5040, but the inventive concepts are not limited to these. In another exemplary embodiment, a common voltage can be applied to semiconductor layers of type 5021, 5031 and 5041 from the first to the third epitaxial cells 5020, 5030 and 5040, and light-emitting signals can be applied to semiconductor layers type p 5025, 5035 and 5045 from the first to the third epitaxial cells 5020, 5030 and 5040.
[0719] [0719] In this way, the first to third epitaxial cells 5020, 5030 and 5040 are activated according to a light emitting signal applied to each of the epitaxial cells. In particular, the first epitaxial cell 5020 is triggered according to a first light emitting SR signal, the second epitaxial cell 5030 is triggered according to a second light emitting signal SG and the third epitaxial cell 5040 is triggered according to the third SB light emitting signal. In this case, the first, second and third direction signs SR, SG and SB are applied independently to the first to third epitaxial cells 5020, 5030 and 5040 and, as a result, each of the first to third epitaxial cells 5020, 5030 and 5040 are triggered independently. The stacked light-emitting structure can finally provide light of various colors by combining the first to the third color emitted above the first to the third epitaxial cell 5020, 5030 and 5040.
[0720] [0720] The stacked light-emitting structure, according to an exemplary embodiment, can implement a color in such a way that portions of light of a different color are provided in the overlapping region, instead of implementing light of a different color in different planes, away from each other, providing, with advantage, compactness and integration of the light emitting element. In a conventional light-emitting element, to obtain full colors, the light-emitting elements that emit different colors, such as red, green and blue light, are generally separated from each other in a plane, which would occupy a relatively large area like each other. of the light-emitting elements is laid out in a plane. However, in the stacked light-emitting structure, according to an exemplary embodiment, it is possible to obtain a full color in a noticeably smaller area compared to the conventional light-emitting element, providing a stacked structure with the portions of the light-emitting elements that emit light of a different color overlapping in one region. Consequently, it is possible to manufacture a high resolution device even in a small area.
[0721] [0721] In addition, the stacked light-emitting structure, according to an exemplary modality, significantly reduces defects that may occur during manufacture. In particular, the light-emitting stacked structure can be manufactured by stacking in the order of the first to third epitaxial cells in which case the second epitaxial cell is stacked in a state where the first epitaxial cell is stacked and the third epitaxial cell is stacked in one state in which the first and second epitaxial cells are stacked. However, as the first to third epitaxial cells are manufactured first on a separate temporary substrate and then stacked when transferred to the substrate, defects may occur during the transfer to the substrate and removal of the temporary substrate, from the first to the third epitaxial cells and other components of the first to third epitaxial cells can be exposed to stress or impact. However, since the light-emitting stacked structure, according to an exemplary embodiment, includes a buffer layer, or a stress or shock absorbing layer, between adjacent epitaxial cells, defects that can occur during processing can be reduced .
[0722] [0722] In addition, the conventional light-emitting device has a complex structure and therefore requires a complicated manufacturing process, especially when implemented as micro LEDs, which require separate preparation of the respective ones as micro LEDs and the formation of separate contacts , such as connecting it by interconnection lines or others, for each of the light-emitting elements. However, according to an exemplary embodiment, the stacked structure of micro LEDs is formed by stacking several layers of epitaxial cells sequentially on a single 5010 substrate and then forming contacts in the multilayer epitaxial cells and connecting by lines through minimal process. In addition, since the individual colored micro LEDs are manufactured and assembled separately, only a single stacked structure is assembled according to an exemplary embodiment, rather than a plurality of light-emitting elements. Therefore, the manufacturing method is significantly simplified.
[0723] [0723] The stacked light-emitting structure, according to an exemplary embodiment, can additionally employ several components to provide high purity and high-efficiency colored light. For example, a stacked structure of micro
[0724] [0724] In the following exemplary modalities, in order to avoid redundant descriptions, the differences in the exemplary modalities described above will mainly be described.
[0725] [0725] FIG. 83 is a cross-sectional view of a stacked light-emitting structure including a filter of passage of predetermined wavelength according to an exemplary embodiment.
[0726] [0726] Referring to FIG. 83, a first wavelength pass filter 5071 can be provided between the first epitaxial cell 5020 and the second epitaxial cell 5030 in a stacked light-emitting structure, according to an exemplary embodiment.
[0727] [0727] The first 5071 wavelength pass filter selectively transmits a certain wavelength light and can transmit a first colored light emitted from the first 5020 epitaxial cell while blocking or reflecting light other than the first colored light. Therefore, the first colored light emitted from the first epitaxial cell 5020 can travel in the upper direction, while the second and third colored light emitted from the second and third epitaxial cells 5030 and 5040 are prevented from traveling towards the first epitaxial cell 5020, and can be reflected or blocked by the first 5071 wavelength pass filter.
[0728] [0728] The second and third color light are high energy light that can have a relatively shorter wavelength than the first color light, which can emit additional light emission in the first 5020 epitaxial cell upon entering the first epitaxial cell 5020. In an exemplary embodiment, the second and third colored lights can be prevented from entering the first 5020 epitaxial cell by the first 5071 wavelength pass filter.
[0729] [0729] In an exemplary embodiment, a second 5073 wavelength pass filter can be provided between the second 5030 epitaxial cell and the third 5040 epitaxial cell. The second 5073 wavelength pass filter transmits the first color light. and the second color light emitted from the first and second epitaxial cells 5020 and 5030, while blocking or reflecting light different from the first and second color light. Therefore, the first and second color light emitted by the first and second epitaxial cells 5020 and 5030 can travel in the upper direction, while the third color light emitted by the third epitaxial cell 5040 cannot travel in one direction towards the first and second epitaxial cells 5020 and 5030, but reflected or blocked by the second 5073 wavelength pass filter.
[0730] [0730] As described above, the third color light is a relatively high energy light, with a shorter wavelength than the first and second color light and, when entering the first and second 5020 and 5030 epitaxial cells, the third colored light can induce additional emission in the first and second epitaxial cells 5020 and 5030. In an exemplary embodiment, the second 5073 wavelength pass filter prevents the third light from entering the first and second epitaxial cells 5020 and 5030 .
[0731] [0731] The first and second 5071 and 5073 wavelength pass filters can be formed in various forms and can be formed by insulating films stacked alternately with different refractive indices. For example, the wavelength of the transmitted light can be determined by alternately stacking SiO2 and TiO2 and adjusting the thickness and stacking number of SiO2 and TiO2. Insulation films with different refractive indices can include SiO2, TiO2, HfO2, Nb2O5, ZrO2, Ta2O5 or others.
[0732] [0732] When the first and second 5071 and 5073 wavelength pass filters are formed by stacking inorganic insulating films with different refractive indexes from each other, defects due to stress or impact during the manufacturing process, for example , peeling or cracking may occur. However, according to an exemplary embodiment, these defects can be significantly reduced by providing a buffer layer to alleviate the impact.
[0733] [0733] The stacked light-emitting structure, according to an exemplary embodiment, can additionally employ several components to provide uniform light of high efficiency. For example, a stacked light-emitting structure, according to an exemplary embodiment, may have several irregularities (or rough surfaces) in the light-emitting surface. For example, a stacked light-emitting structure, according to an exemplary embodiment, may have irregularities formed on the upper surface of at least one n-type semiconductor layer from the first to the third epitaxial cells 5020, 5030 and 5040.
[0734] [0734] In an exemplary embodiment, the irregularities of each epitaxial cell can be formed selectively. For example, irregularities can be provided in the first epitaxial cell 5020, irregularities can be provided in the first and third epitaxial cells 5020 and 5040, or irregularities can be provided in the first to third epitaxial cells 5020, 5030 and 5040. The irregularities in each of the epitaxial cells can be provided in a n-type semiconductor layer corresponding to the emission surface of each of the epitaxial cells.
[0735] [0735] Irregularities are provided to increase the efficiency of light emission and can be provided in several ways, such as a polygonal pyramid, a hemisphere or planes with a surface roughness in a random arrangement. Irregularities can be textured through various engraving processes or using a standardized sapphire substrate.
[0736] [0736] In an exemplary embodiment, the first to third colored light of the first to third epitaxial cells 5020, 5030 and 5040 can have different light intensities, and this difference in intensity can lead to differences in visibility. The efficiency of the light emission can be improved by the selective formation of irregularities in the light output surface of the first to the third epitaxial cells 5020, 5030 and 5040, which results in the reduction of the differences in visibility between the first and the third colored light . The light of the color corresponding to the color red and / or blue may have less visibility than the color green; in this case, the first epitaxial cell 5020 and / or the third epitaxial cell 5040 can be textured to reduce the difference in visibility. In particular, when the lowest stack of light emitters emits red light, the light intensity may be small. As such, the luminous efficiency can be increased by the formation of irregularities on its upper surface.
[0737] [0737] The stacked light-emitting structure with the structure described above is a light-emitting element capable of expressing various colors and therefore can be used as a pixel in a display device. In the exemplary embodiment below, a display device will be described as including the stacked light-emitting structure according to exemplary embodiments.
[0738] [0738] FIG. 84 is a plan view of a display device according to an exemplary embodiment, and FIG. 85 is an enlarged plan view showing a portion P1 of FIG.
[0739] [0739] Referring to FIGS. 84 and 85, a display device 5110 according to an exemplary embodiment can display any visual information, text, video, photographs, two-dimensional or three-dimensional image, or others.
[0740] [0740] The 5110 display device can be supplied in a variety of forms, including a closed polygon that includes a straight side, such as a rectangle or circle, an ellipse or the like, which includes a curved side, a semicircle or semi-ellipse that includes a combination of straight and curved sides. In an exemplary embodiment, the display device will be described as having substantially a rectangular shape.
[0741] [0741] The 5110 display device includes a plurality of 5110 pixels to display an image. Each of the 5110 pixels can be a minimum unit to display the image. Each 5110 pixel includes the stacked light-emitting structure with the structure described above and can emit white light and / or colored light.
[0742] [0742] In an exemplary embodiment, each pixel includes a first 5110R pixel that emits red light, a second 5110G pixel that emits green light, and a third 5110B pixel that emits blue light. The first to third pixels 5110R, 5110G and 5110B can correspond to the first to third epitaxial cells 5020, 5030 and 5040 of the stacked light-emitting structure described above, respectively.
[0743] [0743] The 5110 pixels are arranged in a matrix. As used here, pixels arranged in "a matrix" may not only refer to when 5110 pixels are arranged in a row along the line or column, but also when 5110 pixels are arranged in any repetitive pattern, as generally along rows and columns, with certain changes in details, such as 5110 pixels, being arranged in a zigzag shape, for example.
[0744] [0744] FIG. 86 is a structural diagram of a display device, according to an exemplary embodiment.
[0745] [0745] Referring to FIG. 86, the display device 5110 according to an exemplary embodiment includes a timing controller 5350, a scan driver 5310, a data driver 5330, a spinning unit and pixels. When the pixels include a plurality of pixels, each of the pixels is individually connected to the 5310 scan driver, the 5330 data driver or the like via a portion of the wiring.
[0746] [0746] The 5350 timing controller receives various control signals and image data necessary to drive the display device from the outside (for example, a system for transmitting image data). The 5350 timing controller reorganizes the received image data and transmits the image data to the 5330 data driver. In addition, the 5350 timing controller generates scan control signals and data control signals necessary to drive the image driver. scan 5310 and 5330 data driver and transmit the scan control signals and data control signals that are generated to the 5310 scan driver and 5330 data driver.
[0747] [0747] The scan driver 5310 receives scan control signal from the 5350 timing controller and generates a corresponding scan signal. The 5330 data driver receives data control signal and image data from the 5350 timing controller, and generates corresponding data signals.
[0748] [0748] The wiring unit includes a plurality of signal lines. The wiring portion includes the 5130 scan lines connecting the 5310 scan driver and the pixels and the 5120 data lines connecting the 5330 data driver and the pixels. The scan lines 5130 can be connected to the respective pixels and, consequently, the scan lines 5130 corresponding to the respective pixels are marked as first to third scan lines 5130R, 5130G and 5130B (hereinafter, collectively referred to as '5130' ).
[0749] [0749] In addition, the wiring unit includes lines connecting between the 5350 timing controller to the 5310 scanning driver, the 5350 timing controller and the 5330 data driver or other components and transmitting the signals.
[0750] [0750] The 5130 scan lines provide the scan signals generated from the 5310 scan driver to the pixels. The data signals generated from the 5330 data driver are sent to the 5120 data lines.
[0751] [0751] The pixels are connected to the 5130 scan lines and 5120 data lines. The pixels selectively emit light in response to the data signals emitted from the 5120 data lines when the scan signals are provided from the scan lines 5130. For example, during each frame period, each pixel emits light with the corresponding luminance for the input data signals. The pixels provided with the data signals corresponding to the black luminance display black, emitting no light during the corresponding frame period.
[0752] [0752] In an exemplary mode, pixels can be activated as either passive or active. When the display device is activated in an active manner, the display device can be supplied with the first and second pixel power in addition to the scan signals and the data signals.
[0753] [0753] FIG. 87 is a one-pixel circuit diagram of a passive display device. The pixel can be one of the R, G, B pixels and the first 5110R pixel is illustrated as an example. Since the second and third pixels can be triggered in substantially the same way as the first pixel, circuit diagrams for the second and third pixels will be omitted.
[0754] [0754] Referring to FIG. 87, the first pixel 5110R includes an emitting element 150 connected between the scan line 5130 and the data line 5120. The light emitting element 150 can correspond to the first 5020 epitaxial cell. The 5020 epitaxial cell emits light with a luminance corresponding to a magnitude of the applied voltage when a voltage equal to or greater than a threshold voltage is applied between the p-type semiconductor layer and the n-type semiconductor layer. In particular, the emission of the first 5110R pixel can be controlled by controlling the voltages of the scan signal applied to the first scan line 5130R and / or the data signal applied to the data line
[0755] [0755] FIG. 88 is a circuit diagram of a first pixel of an active type display device.
[0756] [0756] When the display device is of the active type, the first 5110R pixel can be supplied with the first and second pixel power (ELVDD and ELVSS) in addition to the scan signal and the data signal.
[0757] [0757] Referring to FIG. 88, the first pixel 5110R includes a light-emitting element 150 and a part of the transistor connected thereto. The light-emitting element 150 can correspond to the first epitaxial cell 5020, and the p-type semiconductor layer of the light-emitting element 150 can be connected to the first ELVDD pixel power through the transistor part and the n-type semiconductor layer can be connected. connected to a second ELVSS pixel. The first ELVDD pixel power source and the second ELVSS pixel power source can have different potentials. For example, the second subpixel ELVSS power source is smaller than the first ELVDD pixel power source, by at least the threshold voltage of the light emitting element. Each of these light-emitting elements emits a luminance corresponding to a driving current controlled by the transistor part.
[0758] [0758] According to an exemplary embodiment, the transistor part includes the first and second transistors M1 and M2 and a Cst storage capacitor. However, the inventive concepts are not limited to these and the structure of the transistor part can be varied.
[0759] [0759] The source electrode of the first M1 transistor (for example, a switching transistor) is connected to the 5120 data line, and a drain electrode is connected to a first N1 node. In addition, a gate electrode from the first transistor is connected to the first scan line 5130R. The first transistor is activated when a scan signal of a voltage capable of connecting the first transistor M1 is provided from the first scan line 5130R to the data line 5120, to electrically connect the first node N1. The data signal of the corresponding frame is supplied to data line 5120 and, therefore, the data signal is transmitted to the first node N1. The data signal transmitted to the first node N1 is loaded into the storage capacitor Cst.
[0760] [0760] The source electrode of the second transistor M2 is connected to the first pixel energy source ELVDD, and a drain electrode is connected to the first type n semiconductor layer of the light emitting element. The gate electrode of the second transistor M2 is connected to the first node N1. The second transistor M2 controls an amount of drive current supplied to the light-emitting cell in response to the voltage of the first node N1.
[0761] [0761] One electrode of the Cst storage capacitor is connected to the first ELVDD subpixel power source, and the other electrode is connected to the first N1 node. The storage capacitor Cst carries a voltage corresponding to the data signal supplied to the first node N1 and keeps the voltage charged until the data signal of the next frame is supplied.
[0762] [0762] FIG. 88 shows a part of the transistor including two transistors. However, the inventive concepts are not limited to these, and several modifications are applicable to the structure of the transistor part. For example, the transistor part may include more transistors, capacitors or the like. In addition, although the specific structures of the first and second transistors, storage capacitors and lines are not shown, the first and second transistors, storage capacitors and lines are not particularly limited and can be provided in a variety of ways.
[0763] [0763] Pixels can be implemented in various structures within the scope of inventive concepts. In the following, a pixel, according to an exemplary embodiment, will be described with reference to a pixel of the passive matrix type.
[0764] [0764] FIG. 89 is a plan view of a pixel according to an exemplary embodiment, and FIGS. 90A and 90B are cross-sectional views taken along lines I-I 'and II-II' of FIG. 89, respectively.
[0765] [0765] Referring to FIGS. 89, 90A and 90B, viewing from a flat view, a pixel, according to an exemplary embodiment, includes a light-emitting region in which a plurality of epitaxial cells are stacked and a peripheral region surrounding the light-emitting region. The plurality of epitaxial cells includes the first to third epitaxial cells 5020, 5030 and 5040.
[0766] [0766] When viewed from a flat view, the pixel, according to an exemplary embodiment, has a light-emitting region in which a plurality of epitaxial cells are stacked. At least one side of the light-emitting region is provided with a contact to connect the wiring part to the first and third 5020, 5030 and 5040 epitaxial cells. The contact includes the first and second common contacts 5050GC and 5050BC to apply a common voltage to the first and third epitaxial cells 5020, 5030 and 5040, a first contact 5020C to provide a light emitting signal for the first epitaxial cell 5020, a second contact 5030C to provide a light emitting signal to the second epitaxial cell 5030 and a third contact 5040C to provide a light emitting signal for the third 5040 epitaxial cell.
[0767] [0767] In an exemplary embodiment, the stacked structure can vary depending on the polarity of the semiconductor layers from the first to the third 5020, 5030 and 5040 epitaxial cells to which the common voltage is applied. That is, with respect to the first and second common contacts 5050GC and 5050BC, when contact electrodes are provided to apply a common voltage to each of the first to third epitaxial cells 5020, 5030 and 5040, these contact electrodes can be referred to as " first to the third common contact electrode pad "and the first to the third contact electrode pad can be the" first to the third type p contact electrode pad ", respectively, when the common voltage is applied to the semiconductor layer of the type P. In an exemplary embodiment in which a common voltage is applied to the n-type semiconductor layer, the first to the third common contact electrode pad can be the first to the third type n contact electrode pad, respectively. In the following, a common voltage will be described as being applied to a p-type semiconductor layer and thus the first to the third common contact electrode pad will be described as corresponding to the first to the third type p contact electrode pad,
[0768] [0768] In an exemplary embodiment, when viewed from a flat view, the first and second common contacts 5050GC and 5050BC and the first to third contacts 5020C, 5030C and 5040C can be supplied in various positions. For example, when the light-emitting stacked structure is substantially square in shape, the first and second common contacts 5050GC and 5050BC and the first to third contacts 5020C, 5030C and 5040C can be arranged in regions corresponding to the respective corners of the square. However, the positions of the first and second common contacts 550GC and 550BC and the first to third contacts 5020C, 5030C and 5040C are not limited to these, and several modifications are applicable according to the shape of the stacked light-emitting structure.
[0769] [0769] The plurality of epitaxial cells includes the first to third epitaxial cells 5020, 5030 and 5040. The first to third epitaxial cells 5020, 5030 and 5040 are connected with the first to third light-emitting signal lines to provide light emitting signals. light to each of the first to third epitaxial cells 5020, 5030 and 5040 and a common line to provide a voltage common to each of the first to third epitaxial cells 5020, 5030 and 5040. In an exemplary embodiment, the first to third lines of light-emitting signal can correspond to the first to third scan lines 5130R, 5130G and 5130B, and the common line can correspond to data line 5120. Therefore, the first to third scan lines 5130R, 5130G and 5130B and the 5120 data is connected to the first to third epitaxial cells 5020, 5030 and 5040, respectively.
[0770] [0770] In an exemplary embodiment, the first to third scan lines 5130R, 5130G and 5130B can extend substantially in a first direction (for example, in a transverse direction, as shown in the drawing). The data line 5120 can extend substantially in a second direction, crossing the first the third scan lines 5130R, 5130G and 5130B (for example, in a longitudinal direction, as shown in the drawing). However, the extension directions from the first to the third scan line 5130R, 5130G and 5130B and the data line 5120 are not limited to these, and several modifications are applicable according to the arrangement of the pixels.
[0771] [0771] Data line 5120 and the first 5025p type p contact electrode extend substantially in a second direction that crosses the first direction, while providing a voltage common to the type p semiconductor layer of the first epitaxial cell 5020. Therefore, the 5120 data line and the first 5025p type p contact electrode can be substantially the same component. In the following, the first contact electrode of type p 5025p can be referred to as data line 5120 or vice versa.
[0772] [0772] An ohmic electrode 5025p 'for ohmic contact between the first contact electrode of type p 5025p and the first epitaxial cell 5020 is supplied in the light emitting region provided with the first contact electrode of type p 5025p.
[0773] [0773] The first scan line 5130R is connected to the first epitaxial cell 5020 through the first contact hole CH1 and the data line 5120 is connected via the ohmic electrode 5025p '. The second scan line 5130G is connected to the second epitaxial cell 5030 through the second contact hole CH2 and the data line 5120 is connected through the contact holes 4ath and 4bth CH4a and CH4b. The third scan line 5130B is connected to the third epitaxial cell 5040 through the third contact hole CH3 and the data line 5120 is connected through the contact holes 5ath and 5bth CH5a and CH5b.
[0774] [0774] A buffer layer, a contact electrode, a wavelength pass filter or the like are provided between substrate 5010 and the first to third epitaxial cells 5020, 5030 and 5040, respectively. Next, the pixel, according to an exemplary mode, will be described in the stacking order.
[0775] [0775] According to an exemplary embodiment, a first epitaxial cell 5020 is provided on the substrate 5010 through an adhesive layer 5061 interposed between them. In the first epitaxial cell 5020, a p-type semiconductor layer, an active layer and an n-type semiconductor layer are arranged sequentially from the bottom side to the top side.
[0776] [0776] A first insulating film 5081 is stacked on a lower surface of the first epitaxial pile 5020, that is, on the surface facing the substrate 5010. A plurality of contact holes are formed in the first insulation film
[0777] [0777] The first contact electrode of type p 5025p and data line 5120 are in contact with the ohmic electrode 5025p ’. The first p 5025p contact electrode (also serving as data line 5120) is provided between the first insulating film 5081 and the adhesive layer 5061.
[0778] [0778] When viewed from a flat view, the first p 5025p contact electrode can be provided in such a way that the first p 5025p contact electrode overlaps the first 5020 epitaxial cell, or more particularly, overlaps the light-emitting region of the first 5020 epitaxial cell, while covering most or all of the light-emitting region. The first p 5025p contact electrode may include a reflective material, so that the first p 5025p contact electrode can reflect the light from the first epitaxial cell
[0779] [0779] In addition, the material of the first 5025p type p contact electrode layer is selected from metals with high reflectivity to the light emitted from the first 5020 epitaxial cell, to maximize the reflectivity of the light emitted from the first epitaxial cell 5020. For example, when the first 5020 epitaxial cell emits red light, the metal with a high reflectivity to red light, for example Au, Al, Ag or the like can be used as material for the first contact electrode layer of the type p 5025p. Au does not have a high reflectivity to the light emitted by the second and third epitaxial cells 5030 and 5040 (for example, green light and blue light) and, therefore, can reduce a mixture of colors by the light emitted by the second and third epitaxial cells 5030 and 5040 .
[0780] [0780] The first 5071 wavelength pass filter and the first n 5021n contact electrode are provided on an upper surface of the first 5020 epitaxial cell. In an exemplary embodiment, the first n 5021n contact electrode can include various metals and metal alloys, including Au / Te alloy or Au / Ge alloy, for example.
[0781] [0781] The first 5071 wavelength pass filter is provided on the top surface of the first 5020 epitaxial cell to cover substantially the entire light-emitting region of the first 5020 epitaxial cell.
[0782] [0782] The first contact electrode of type n 5021n is supplied in a region corresponding to the first contact 5020C and may include a conductive material. The first 5071 wavelength pass filter is provided with a contact orifice through which the first type n contact electrode 5021n is placed in contact with the type n semiconductor layer on the top surface of the first 5020 epitaxial cell.
[0783] [0783] The first buffer layer 5063 is provided in the first epitaxial cell 5020, and the second contact electrode of type p 5035p and the second epitaxial cell 5030 are supplied sequentially in the first buffer layer 5063. In the second epitaxial cell 5030, a semiconductor layer p-type, an active layer and a n-type semiconductor layer are arranged sequentially from the bottom to the top.
[0784] [0784] In an exemplary embodiment, the region corresponding to the first contact 5020C of the second epitaxial cell 5030 is removed, thus exposing a portion of the upper surface of the first contact electrode of type n 5021n. In addition, the second 5030 epitaxial cell may have a smaller area than the second type 5035p contact electrode. The region corresponding to the first common 550GC contact is removed from the second 5030 epitaxial cell, thus exposing a portion of the upper surface of the second type 5035p contact electrode.
[0785] [0785] The second 5073 wavelength pass filter, the second layer of buffer 5065 and the third p type contact electrode 5045p are supplied sequentially in the second epitaxial cell 5030. The third epitaxial cell 5040 is provided in the third electrode contact type p 5045p. In the third epitaxial cell 5040, a n-type semiconductor layer, an active layer and a p-type semiconductor layer are arranged sequentially from the bottom to the top.
[0786] [0786] The third epitaxial cell 5040 can have a smaller area than the second epitaxial cell 5030. The third epitaxial cell 5040 can have an area smaller than the third contact electrode of type p 5045p. The region corresponding to the second common contact 5050BC is removed from the third epitaxial cell 5040, thus exposing a portion of the upper surface of the third contact electrode of type p 5045p.
[0787] [0787] The second 5083 insulation film covering the stacked structure of the first to third 5020, 5030 and 5040 epitaxial cells is provided in the third 5040 epitaxial cell.
[0788] [0788] The first contact hole CH1 is formed in the second insulation film 5083 to expose an upper surface of the first contact electrode of type n 5021n provided in the first contact 5020C. The first scan line is connected to the first 5021n n type contact electrode through the first CH1 contact orifice.
[0789] [0789] A third insulation film 5085 is provided on the second insulation film 5083. The third insulation film 5085 may include a material substantially the same or different from the second insulation film 5083. The third insulation film 5085 may include various insulating materials organic / inorganic, but is not limited to these.
[0790] [0790] The second and third scan lines 5130G and 5130B and the first and second bridge electrodes BRG and BRB are provided in the third insulation film 5085.
[0791] [0791] The third insulation film 5085 is provided with a second contact hole CH2 to expose an upper surface of the second epitaxial cell 5030 in the second contact 5030C, that is, to expose the n-type semiconductor layer of the second epitaxial cell 5030, a third contact hole CH3 to expose an upper surface of the third epitaxial cell 5040 in the third contact 5040C, that is, to expose a semiconductor type n layer of the third epitaxial cell 5040, 4ath and 4bth contact holes CH4a and CH4b to expose an upper surface of the first contact electrode of type p 5025p and an upper surface of the second contact electrode of type p 5035p, in the first common contact 5050GC and contact holes 5ath and 5bth CH5a and CH5b to expose an upper surface of the first type contact electrode p 5025p and an upper surface of the third contact electrode of the type p 5045p, in the second common contact 5050BC.
[0792] [0792] The second scan line 5130G is connected to the n-type semiconductor layer of the second epitaxial cell 5030 through the second contact hole CH2. The third scan line 5130B is connected to the n-type semiconductor layer of the third epitaxial cell 5040 through the third contact hole CH3.
[0793] [0793] The data line 5120 is connected to the second contact electrode of type p 5035p through the contact holes 4ath and 4bth CH4a and CH4b and the first bridge electrode BRG. The 5120 data line is also connected to the third type 5050p contact electrode pad via the 5ath and 5bth contact holes CH5a and CH5b and the second BRB bridge electrode.
[0794] [0794] It is illustrated in this document that the second and third scan lines 5130G and 5130B in an exemplary mode are electrically connected to the type n semiconductor layer of the second and third epitaxial cells 5030 and 5040 in direct contact with each other. However, in another exemplary embodiment, the second and third type n contact electrodes can still be provided between the second and third scan lines 5130G and 5130B and the type n semiconductor layers of the second and third epitaxial cells 5030 and 5040.
[0795] [0795] According to an exemplary modality,
[0796] [0796] Furthermore, in an exemplary embodiment, a substantially non-transmitting film can still be provided on the sides of the second and / or third insulation films 5083 and 5085 that correspond to the sides of the pixel. Non-transmitting film is a light blocking film that includes a light-absorbing or reflective material, which is provided to prevent light from the first to third 5020, 5030 and 5040 epitaxial cells from appearing on the sides of the pixel.
[0797] [0797] In an exemplary embodiment, the optically non-transmitting film can be formed as a single or multilayer metal. For example, the optically non-transmitting film can be formed from a variety of materials, including metals such as Al, Ti, Cr, Ni, Au, Ag, Ti, Sn, Ni, Cr, W, Cu or others, or alloys thereof .
[0798] [0798] The optically non-transmitting film can be provided on the side of the second insulating film 5083 as a separate layer formed of a material such as metal or alloy thereof.
[0799] [0799] The optically non-transmitting film can be supplied in a way that extends laterally from at least one of the first to the third scan lines 5130R, 5130G and 5130B and the first and second bridge electrodes BRG and BRB.
[0800] [0800] In addition, a substantially non-transmitting film can be provided, formed separately from the first to third scan lines 5130R, 5130G and 5130B and the first and second bridge electrodes BRG and BRB on the same layer and using substantially the same material during the same process of forming at least one of the first to third scan lines 5130R, 5130G and 5130B and the first and second bridge electrodes BRG and BRB. In this case, the non-transmitting film can be electrically isolated from the first to the third scan lines 5130R, 5130G and 5130B and the first and second bridge electrodes BRG and BRB.
[0801] [0801] Alternatively, when no optically non-transmitting film is supplied separately, the second and third insulating films 5083 and 5085 can serve as optically non-transmitting films. When the second and third insulating films 5083 and 5085 are used as an optically non-transmitting film, the second and third insulating films 5083 and 5085 may not be provided in a region corresponding to an upper portion (front direction) from the first to the third epitaxial cells 5020, 5030 and 5040 to allow the light emitted from the first to third epitaxial cells 5020, 5030 and 5040 to travel in the frontal direction.
[0802] [0802] The substantially non-transmitting film is not particularly limited as long as it blocks the transmission of light by absorbing or reflecting light. In an exemplary embodiment, the non-transmitting film can be a dielectric mirror distributed by a Bragg reflector (DBR), a metal reflective film formed in an insulation film, or a black organic polymer film. When a metal reflective film is used as a non-transmitting film, the metal reflective film may be in a floating state that is electrically isolated from components within other pixels.
[0803] [0803] By supplying the non-transmitting film on the sides of the pixels, it is possible to avoid the phenomenon in which the light emitted by a given pixel affects the adjacent pixels or in which the color is mixed with the light emitted by the adjacent pixels.
[0804] [0804] The pixel that has the structure described above can be manufactured by sequentially stacking the first to third epitaxial cells 5020, 5030 and 5040 on the substrate 5010 sequentially and standardizing it, which will be described in detail below.
[0805] [0805] FIGS. 91A to 91C are seen in cross section of line I-I 'in FIG. 89, illustrating a process of stacking the first to third epitaxial cells on a substrate.
[0806] [0806] Referring to FIG. 91A, the first epitaxial cell 5020 is formed on the substrate 5010.
[0807] [0807] The first epitaxial cell 5020 and the ohmic electrode 5025p 'are formed on a first temporary substrate 5010p. In an exemplary embodiment, the first temporary substrate 5010p can be a semiconductor substrate, such as a GaAs substrate, to form the first 5020 epitaxial cell. The first 5020 epitaxial cell is manufactured in a way to stack the n-type semiconductor layer, the active layer and the p-type semiconductor layer on the first temporary substrate 5010p. The first insulation film 5081 having a contact orifice formed on it is formed on the first temporary substrate 5010p, and the ohmic electrode 5025p 'is formed within the contact orifice of the first insulation film 5081.
[0808] [0808] The ohmic electrode 5025p 'is formed by forming the first insulation film 81 on the first temporary substrate 5010p, applying photoresist, standardizing the photoresistor, depositing an ohmic electrode material 5025p' on the standardized photoresistor and then removing the pattern photoresistor. However, the method of forming the 5025p ohmic electrode is not limited to this. For example, the first insulation film 81 can be formed by forming the first insulation film 81, standardizing the first insulation film 81 by photolithography, forming the ohmic electrode film 5025p 'with the material of the ohmic electrode film 5025p' and standardizing the ohmic electrode film 5025p 'by photolithography.
[0809] [0809] The first 5025p type p contact electrode layer (also serving as data line 5120) is formed on the first temporary substrate 5010p on which the ohmic electrode 5025p 'is formed. The first 5025p type p contact electrode layer may include a reflective material. The first layer of contact electrode type p 5025p can be formed by, for example, depositing a metallic material and then standardizing it using photolithography.
[0810] [0810] The first epitaxial cell 5020 formed on the first temporary substrate 5010p is inverted and fixed to the substrate 5010 through the adhesive layer 5061 interposed between them.
[0811] [0811] After the first 5020 epitaxial cell is attached to substrate 5010, the first temporary substrate 5010p is removed. The first temporary substrate 5010p can be removed by various methods, such as wet engraving, dry engraving, physical removal, laser lifting or the like.
[0812] [0812] Referring to FIG. 91B, after removing the first temporary substrate 5010p, the first type n contact electrode 5021n, the first wavelength pass filter 5071 and the first adhesion enhancement layer 5063a are formed in the first epitaxial cell 5020. The first contact electrode type n 5021n can be formed by depositing a conductive material and then standardizing by the photolithography process. The first 5071 wavelength pass filter can be formed by alternately stacking insulation films with different refractive indices from one another.
[0813] [0813] After removing the first temporary substrate 5010p, irregularities can be formed on an upper surface (type n semiconductor layer) of the first epitaxial cell
[0814] [0814] The second epitaxial cell 5030, the second contact electrode type p 5035p and the first shock absorbing layer 5063b are formed on a separate second temporary substrate 5010q.
[0815] [0815] The second temporary substrate 5010q can be a sapphire substrate. The second epitaxial cell 5030 can be manufactured by forming the n-type semiconductor layer, the active layer and the p-type semiconductor layer on the second temporary substrate 5010q.
[0816] [0816] The second epitaxial cell 5030 formed on the second temporary substrate 5010q is inverted and attached to the first epitaxial cell 5020. In this case, the first layer of adhesion improvement 5063a and the second layer of shock absorption 5063b can be arranged one in front to the other and then joined. In an exemplary embodiment, the first adhesion enhancing layer 5063a and the first shock absorbing layer 5063b can include various materials, such as SOG and silicon oxide, respectively.
[0817] [0817] After connection, the second temporary substrate 5010q is removed. The second temporary 5010q substrate can be removed by various methods, such as wet etching, dry etching, physical removal, laser removal or the like.
[0818] [0818] According to an exemplary embodiment, in the process of attaching the second epitaxial cell 5030 formed on the second temporary substrate 5010q to the substrate 5010, and in the process of removing the second temporary substrate 5010q from the second epitaxial cell 5030, the impact applied on the first epitaxial cell 5020, second epitaxial cell 5030, first wavelength filter pass 5071 and second contact electrode of type p 5035p is absorbed and / or relieved by the first buffer layer 5063, more particularly, by the first shock absorption layer 5063b inside of the first layer 5063. This minimizes the cracking and removal that can occur in the first epitaxial cell 5020, the second epitaxial cell 5030, the first 5071 wavelength pass filter and the second type 5035p contact electrode. More particularly, when the first 5071 wavelength pass filter is formed on the top surface of the first 5020 epitaxial cell, the possibility of removal is remarkably reduced compared to when the first 5071 wavelength pass filter is formed on the side of the second epitaxial cell 5030. When the first 5071 wavelength pass filter is formed on the upper surface of the second epitaxial cell 5030 and then attached to the first side of the epitaxial cell 5020, due to the impact generated in the process of removing the second temporary substrate 5010q, there may be a peeling defect of the first 5071 wavelength pass filter. However, according to an exemplary embodiment, in addition to the first 5071 wavelength pass filter being formed on the first side of the 5020 epitaxial cell, the shock-absorbing effect by the first 5063b shock-absorbing layer can prevent the occurrence of and defects, such as peeling.
[0819] [0819] Referring to FIG. 91C, the second wavelength pass filter 5073 and the second adhesion enhancement layer 5065a are formed in the second epitaxial stack 5030 from which the second temporary substrate 5010q has been removed.
[0820] [0820] The second 5073 wavelength pass filter can be formed by alternately stacking insulation films with different refractive indices from one another.
[0821] [0821] Irregularities can be formed on an upper surface (type n semiconductor layer) of the second 5030 epitaxial cell after removal of the second temporary substrate. Irregularities can be textured through various engraving processes, or they can be formed using a standard sapphire substrate for the second temporary substrate.
[0822] [0822] The third epitaxial cell 5040, the third layer of contact type electrode p 5045p and the second layer of shock absorption 5065b are formed on a separate third temporary substrate 5010r.
[0823] [0823] The third temporary substrate 5010r may be a sapphire substrate. The third epitaxial cell 5040 can be manufactured by forming the n-type semiconductor layer, the active layer and the p-type semiconductor layer on the third temporary substrate 5010r.
[0824] [0824] The third epitaxial cell 5040 formed on the third temporary substrate 5010r is inverted and attached to the second epitaxial cell 5030. In this case, the second layer 5065a of adhesion improvement and the second layer 5065b of shock absorption can be arranged one in front to the other and then joined. In an exemplary embodiment, the second adhesion enhancing layer 5065a and the second shock absorbing layer 5065b can include various materials, such as SOG and silicon oxide, respectively.
[0825] [0825] After fixing, the third temporary substrate 5010r is removed. The third temporary substrate 5010r can be removed by various methods, such as wet etching, dry etching, physical removal, laser lifting or the like.
[0826] [0826] According to an exemplary embodiment, in the process of attaching the third epitaxial cell 5040 formed on the third temporary substrate 5010r to the substrate 5010, and in the process of removing the third temporary substrate 5010r from the third epitaxial cell 5040, the impact applied to the second and third epitaxial cells 5030 and 5040, the second wavelength pass filter 5073 and the third p type contact electrode 5045p are absorbed and / or relieved by the second layer of buffer 5065, in particular, by the second layer of absorption of shock 5065b within the second buffer layer 5065.
[0827] [0827] Therefore, all the first to third epitaxial cells 5020, 5030 and 5040 are stacked on the substrate 5010.
[0828] [0828] Irregularities can be formed on an upper surface (type n semiconductor layer) of the third 5040 epitaxial cell after removal of the second temporary substrate. The irregularities can be textured through various engraving processes or can be formed using a sapphire substrate standardized for the second temporary substrate 5010q.
[0829] [0829] Next, a method of manufacturing a pixel will be described, standardizing epitaxial cells stacked according to an exemplary modality.
[0830] [0830] FIGS. 92, 94, 96, 98, 100, 102 and 104 are plan views showing sequentially a method of manufacturing a pixel on a substrate according to an exemplary embodiment.
[0831] [0831] FIGS. 93A, 93B, 95A, 95B, 97A, 97B, 99A, 99B, 101A, 101B, 103A, 103B, 105A and 105B are views taken along line I-I 'and line II-II' of the corresponding figures, respectively.
[0832] [0832] Referring to FIGS. 92, 93A and 93B, first, the third 5040 epitaxial cell is standardized. Most of the third 5040 epitaxial cell, except for the light emitting region, is removed and, in particular, the portions corresponding to the first and second contacts 5030C and the first and second common contacts 5050GC and 5050BC are removed. The third 5040 epitaxial cell can be removed by various methods, such as wet etching or dry etching using photolithography, and the third p 5045p type contact electrode can function as a recording stopper.
[0833] [0833] Referring to FIGS. 94, 95A and 95B, the third p type contact electrode 5045p, the second layer of buffer 5065 and the second wavelength pass filter 5073 are removed from the region, excluding the light emitting region. As such, a portion of the upper surface of the second epitaxial cell 5030 is exposed at the second contact 5030C.
[0834] [0834] The third p 5045p type contact electrode, the second 5065 buffer layer and the second 5073 wavelength pass filter can be removed by various methods, such as wet recording or dry recording using photolithography.
[0835] [0835] Referring to FIGS. 96, 97A and 97B, a portion of the second 5030 epitaxial cell is removed, exposing a portion of the upper surface of the second type 5035p contact electrode to the second common contact 5050GC to the outside. The third contact electrode of type p 5045p serves as an engraving stopper during engraving.
[0836] [0836] Next, parts of the second p type contact electrode 5035p, the first layer of buffer 5063 and the first pass filter of wavelength 5071 are recorded. Accordingly, the upper surface of the first n-type contact electrode 5021n is exposed in the first contact 5020C, and the upper surface of the first epitaxial cell 5020 is exposed in portions other than the light-emitting region.
[0837] [0837] The second epitaxial cell 5030, the second p type contact electrode 5035p, the first buffer layer 5063 and the first 5071 wavelength pass filter can be removed by various methods, such as wet recording or dry recording using photolithography.
[0838] [0838] Referring to FIGS. 98, 99A and 99B, the first 5020 epitaxial cell and the first 5081 insulation film are recorded in the region excluding the light-emitting region. The upper surface of the first 5025p type p contact electrode is exposed on the first and second common contacts 5050GC and 5050BC.
[0839] [0839] Referring to FIGS. 100, 101A and 102B, the second insulation film 5083 is formed in front of the substrate 5010 and first to the third contact holes CH1, CH2, CH3, contact holes 4ath and 4bth CH4a and CH4b and 5ath and 5bth the contact holes CH5a and CH5b are formed.
[0840] [0840] After deposition, the second 5083 insulation film can be standardized by various methods, such as wet recording or dry recording using photolithography.
[0841] [0841] Referring to FIGS. 102, 103A and 103B, the first scan line 5130R is formed on the second standardized insulation film 5083. The first scan line 5130R is connected to the first contact electrode of type n 5021n through the first contact hole CH1 on the first contact 5020C .
[0842] [0842] The first scan line 5130R can be formed in several ways. For example, the first scan line 5130R can be formed by photolithography using a plurality of mask sheets.
[0843] [0843] Next, the third insulation film 5085 is formed on the front of the substrate 5010, and the second and third contact holes CH2 and CH3, the contact holes 4ath and 4bth CH4a and CH4b and the contact holes 5ath and 5bth CH5a and CH5b are formed.
[0844] [0844] After deposition, the third 5085 insulation film can be standardized by various methods, such as wet recording or dry recording using photolithography.
[0845] [0845] Referring to FIGS. 104, 105A and 105B, the second scan line 5130G, the third scan line 5130B, the first BRG bridge electrode and the second BRB bridge electrode are formed from a third standardized 5085 insulation film.
[0846] [0846] The second scan line 5130G is connected to the type n semiconductor layer of the second 5030 epitaxial cell through the second contact hole CH2 on the second contact 5030C. The third scan line 5130B is connected to the n-type semiconductor layer of the fourth epitaxial cell 5040 through a third contact hole CH3 in the third contact 5040C. The first BRG bridge electrode is connected to the first 5025p type p contact electrode through the 4ath and 4bth CH4a and CH4b contact holes in the first 5050GC common contact. The second BRB bridge electrode is connected to the first type 5025p contact electrode through the 5ath and 5bth contact holes CH5a and CH5b on the second common contact 5050BC.
[0847] [0847] The second scan line 5130G, the third scan line 5130B and the bridge electrode 5120b can be formed on the third insulation film 5085 in several ways, for example, by photolithography using a plurality of mask sheets.
[0848] [0848] The second scan line 5130G, the third scan line 5130B and the first and second bridge electrodes BRG and BRB can be formed by applying photoresist to substrate 5010 on which the third insulation film 5085 is formed and standardizing the photoresistor and depositing materials from the second scan line, the third scan line and the bridge electrode to the standard photoresistor and then removing the photoresistor pattern.
[0849] [0849] According to an exemplary embodiment, the order of formation of the first to third scan lines 5130R, 5130G and 5130B and the first and second bridge electrodes BRG and BRB of the wiring part is not particularly limited and can be formed in multiple strings. For example, it is illustrated that the second scan line 5130G, the third scan line 5130B and the first and second bridge electrodes BRG and BRB are formed on the third insulation film 5085 on the same stage, but can be formed in an order different. For example, the first scan line 5130R and the second scan line 5130G can be formed first in the same step, followed by the formation of the additional insulation film and then by the third scan line 5130B. Alternatively, the first scan line 5130R and the third scan line 5130B can be formed first in the same step, followed by the formation of the additional insulation film and then the formation of the second scan line 5130G. In addition, the first and second BRG and BRB bridge electrodes can be formed together in any of the forming steps from the first to the third scan lines 5130R, 5130G and 5130B.
[0850] [0850] In addition, in an exemplary embodiment, the positions of the contacts of the respective epitaxial cells 5020, 5030 and 5040 can be formed differently, in which case the positions of the first to the third scan lines 5130R, 5130G and 5130B and the first and second BRG and BRB bridge electrodes can also be changed.
[0851] [0851] In an exemplary embodiment, an optically non-transmitting film can also be provided in the second insulation film 5083 or in the third insulation film 5085, in the fourth insulation film corresponding to the pixel. The optically non-transmitting film can be formed from a DBR dielectric mirror, a metal reflective film in an insulation film or an organic polymer film. When a metallic reflective film is used as an optically non-transmitting film, it is manufactured in a floating state that is electrically isolated from components in other pixels. In an exemplary embodiment, the optically non-transmitting film can be formed by depositing two or more insulation films with different refractive indexes. For example, the optically non-transmitting film can be formed by stacking a material with a low refractive index and a material with a high refractive index in sequence, or alternatively, formed by alternately stacking insulation films with different refractive indexes one other. Materials with different refractive indexes are not particularly limited, but examples include SiO2 and SiNx.
[0852] [0852] As described above, in a display device according to an exemplary embodiment, it is possible to stack a plurality of epitaxial cells sequentially and then form contacts with a spinning part in a plurality of epitaxial cells at the same time.
[0853] [0853] FIG. 106 is a schematic plan view of a display device, according to an exemplary embodiment, FIG. 107A is a partial cross-sectional view of FIG. 106, and FIG. 107B is a schematic circuit diagram.
[0854] [0854] Referring to FIGS. 106 and 107A, the display device may include a substrate 6021, a plurality of pixels, a first stack of LED 6100, a second stack of LED 6200, a third stack of LED 6300, an insulation layer (or a buffer layer) 6130 with a multilayer structure, a first 6230 color filter, a second 6330 color filter, a first adhesive layer 6141, a second adhesive layer 6161, a third adhesive layer 6261 and a 6350 barrier. In addition, the display device can include multiple electrode pads and connectors.
[0855] [0855] The substrate 6021 supports semiconductor batteries 6100, 6200 and 6300. In addition, the substrate 6021 can have a circuit in it. For example, substrate 6021 may be a silicon substrate on which thin film transistors are formed. TFT substrates are widely used for activating the active matrix of a display field, such as an LCD display field or the like. Since a TFT substrate configuration is well known in the art, its detailed descriptions will be omitted. A plurality of pixels can be activated in an active matrix manner, but the inventive concepts are not limited to these. In another exemplary embodiment, substrate 6021 can include a passive circuit including data lines and scan lines, and thus the plurality of pixels can be driven in a passive matrix manner.
[0856] [0856] A plurality of cells can be disposed on the substrate 6021. The pixels can be separated from each other by a 6350 barrier. The 6350 barrier can be formed by a light reflecting material or a light absorbing material. The 6350 barrier can block light that travels to a neighboring pixel region by reflection or absorption, thereby preventing light interference between pixels. Examples of the light-reflecting material may include a light-reflecting material, such as a white photosensitive solder resistor (PSR), and examples of the light-absorbing material may include black epoxy or the like.
[0857] [0857] Each pixel includes the first to the third battery of LEDs 6100, 6200 and 6300. The second battery of LED 6200 is disposed in the first battery of LED 6100 and the third battery of LED 6300 is disposed in the second battery of LED 6200.
[0858] [0858] The first stack of LED 6100 includes a semiconductor layer of type 6123 and a semiconductor layer of type 6125, the second stack of LED 6200 includes a semiconductor layer of type 6223 and a semiconductor layer of type 6225 and a The third 6300 LED stack includes a n 6323 type semiconductor layer and a 6325 p type semiconductor layer. In addition, the first to the third 6100, 6200 and 6300 LED stack includes an active layer interposed between the 6123 n type semiconductor layer. , 6223 or 6323 and the semiconductor layer type p 6125, 6225 or 6325. The active layer may, in particular, have a multi-quantum well structure.
[0859] [0859] As an LED stack is positioned closer to the 6021 substrate, the LED stack can emit light with a longer wavelength. For example, the first 6100 LED battery can be an inorganic light emitting diode that emits red light, the second 6200 LED battery can be an inorganic light emitting diode that emits green light, and the third 6300 LED battery can be an inorganic LED emitting blue light. For example, the first 6100 LED stack can include an AlGaInP based well layer, the second 6200 LED stack can include an AlGaInP or AlGaInN based well layer and the third 6300 LED stack can include a well based layer in AlGaInN. However, inventive concepts are not limited to these. In particular, when the LED cells include micro LEDs, an LED cell positioned closer to the 6021 substrate can emit light with a shorter wavelength, and the LED cells placed on it can emit light with a longer wavelength. no adverse affectation operation or the need for color filters due to the small form factor of a micro LED.
[0860] [0860] An upper surface of each of the first to the third LED batteries 6100, 6200 and 6300 can be of type n and a lower surface of it can be of type p. According to some exemplary modalities, however, the types of semiconductors on the top and bottom surfaces of each of the LED cells can be reversed.
[0861] [0861] When the top surface of the third 6300 LED stack is type n, the top surface of the third 6300 LED stack can be textured by chemical engraving to form a rough surface (or irregularities). The top surface of the first 6100 LED stack and the second 6200 LED stack can also be roughened by surface texturing. Meanwhile, when the second 6200 LED battery emits green light, since green light has greater visibility than red light or blue light, it is preferable to increase the light emission efficiency of the first 6100 LED battery and the third 6300 LED stack compared to the second 6200 LED stack. Thus, surface texturing can be applied to the first 6100 LED stack and the third 6300 LED stack to improve the efficiency of light extraction, and the second stack of LED 6200 can be used without surface texturing to adjust the intensity of red, green and blue light to similar levels.
[0862] [0862] The light generated in the first battery of LED 6100 can be transmitted through the second and third batteries of LED 6200 and
[0863] [0863] The first 6230 color filter can be disposed between the first 6100 LED stack and the second 6200 LED stack. In addition, the second 6330 color filter can be disposed between the second 6200 LED stack and the third stack 6300 LED filter. The first 6230 color filter transmits light generated in the first 6100 LED stack and reflects the light generated in the second LED stack.
[0864] [0864] In some exemplary embodiments, the first 6230 color filter can reflect the light generated in the third 6300 LED stack.
[0865] [0865] The first and second color filters 6230 and 6330 can be, for example, a low pass filter that passes through only a low frequency region, that is, a long wavelength region, a low pass filter. band that passes through only one band of predetermined wavelength,
[0866] [0866] The first adhesive layer 6141 is disposed between the 6021 substrate and the first 6100 LED stack and connects the first 6100 LED stack to the 6021 substrate. The second 6161 adhesive layer is disposed between the first 6100 LED stack and the second 6200 LED battery and connects the second 6200 LED battery to the first 6100 LED battery. In addition, the third adhesive layer 6261 is placed between the second 6200 LED battery and the third 6300 LED battery and connects the third LED battery 6300 to the second 6200 LED battery.
[0867] [0867] As shown, the second adhesive layer 6161 can be disposed between the first stack of LED 6100 and the first color filter 6230 and can contact the first color filter 6230. The second adhesive layer 6161 transmits light generated in the first 6100 LED stack.
[0868] [0868] The third adhesive layer 6261 can be disposed between the second stack of LED 6200 and the second color filter 6330 and can come in contact with the second color filter 6330. The second adhesive layer 6161 transmits light generated in the first pile of LED 6100 and the second LED stack 6200.
[0869] [0869] Each of the first to third adhesive layers 6141, 6161 and 6261 is formed by an adhesive material that can be standardized. Such adhesive layers 6141, 6161 and 6261 may include, for example, epoxy, polyimide, SU8, spin-on-glass (SOG), benzocyclocyclobutene (BCB) or others, but are not limited to these.
[0870] [0870] A metal bonding material can be arranged in each of the adhesive layers 6141, 6161 and 6261, which are described in more detail below.
[0871] [0871] The 6130 insulation layer is disposed between the first adhesive layer 6141 and the first 6100 LED stack. The 6130 insulation layer has a multilayer structure and can include a first 6131 insulation layer in contact with the first LED stack. 6100 and a second insulation layer 6135 in contact with the first adhesive layer 6141. The first insulation layer 6131 can be formed by a silicon nitride film (SiNx layer) and the second insulation layer 6135 can be formed by a silicon oxide film (SiO2 layer). As the silicon nitride film has a strong adhesive strength to the GaP-based semiconductor layer and the SiO2 layer has a strong adhesive strength to the first 6141 adhesive layer, the first 6100 LED stack can be fixedly attached to the 6021 substrate by stacking the film of silicon nitride and the SiO2 layer.
[0872] [0872] According to an exemplary embodiment, a distributed Bragg reflector can also be disposed between the first 6131 insulation layer and the second 6135 insulation layer. The distributed Bragg reflector prevents the light generated in the first 6100 LED stack absorbed into the substrate 6021, thus improving light efficiency.
[0873] [0873] In FIG. 107A, while the first adhesive layer 6141 is shown and described as being divided into each pixel unit by barrier 6350, the first adhesive layer 6141 can be continuous across a plurality of pixels in some exemplary embodiments. The insulation layer 6130 can also be continuous across a plurality of pixels.
[0874] [0874] The first to third batteries of LED 6100, 6200 and 6300 can be electrically connected to a circuit on substrate 6021 using electrode pads, connectors and ohmic electrodes and therefore, for example, a circuit as shown in FIG. 107B can be implemented. The electrode pads, connectors and ohmic electrodes are described in more detail below.
[0875] [0875] FIG. 107B is a schematic circuit diagram of a display device according to an exemplary embodiment.
[0876] [0876] Referring to FIG. 107B, a drive circuit according to an exemplary embodiment can include two or more transistors Tr1 and Tr2 and a capacitor. When the power supply is connected to the selection lines Vrow1 to Vrow3 and a data voltage is applied to the data lines Vdata1 to Vdata3, a voltage is applied to the corresponding LED. In addition, the charges are charged to the corresponding capacitor according to the values of Vdata1 and Vdata3. An activation state of transistor Tr2 can be maintained by the charged voltage of the capacitor, and thus, even when the power is cut off at the selection line Vrow1, the voltage of the capacitor can be maintained and the voltage can be applied to the LEDs1 to LED3. In addition, the currents that flow through LED1 to LED3 can be changed according to the values from Vdata1 to Vdata3. The current can always be supplied by Vdd and, therefore, continuous light emission is possible.
[0877] [0877] Transistors Tr1 and Tr2 and capacitor can be formed on a substrate of 6021. Here, the light emitting diodes LED1 to LED3 can correspond to the first to third batteries of LED 6100, 6200 and 6300 stacked in one pixel, respectively . The anodes from the first to the third 6100, 6200 and 6300 LED batteries are connected to transistor Tr2 and their cathodes are grounded. The first to the third LED batteries 6100, 6200 and 6300 can be electrically grounded in common.
[0878] [0878] FIG. 107B shows an example circuit diagram for an active matrix drive, but other circuits for the active matrix drive can be used. In addition, according to an exemplary modality, passive matrix driving can also be implemented.
[0879] [0879] In the following, a method of manufacturing a display device will be described in detail.
[0880] [0880] FIGS. 108A to 114 are schematic plan views and cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment. In each of the drawings, the cross-sectional view is taken along the line shown in the corresponding plan view.
[0881] [0881] First, with reference to FIG. 108A, the first 6100 LED stack is grown on the first substrate 6121. The first substrate 6121 can be, for example, a GaAs substrate. The first 6100 LED stack is made up of semiconductor layers based on AlGaInP and includes a n 6123 type semiconductor layer, an active layer and a p 6125 type semiconductor layer. The first 6100 LED stack can have, for example, a composition of Al, Ga and In to emit red light.
[0882] [0882] The semiconductor layer type p 6125 and the active layer are engraved to expose the semiconductor layer type n
[0883] [0883] Referring to FIG. 108B, the ohmic contact layers 6127 and 6129 are formed. The ohmic contact layers 6127 and 6129 can be formed for each pixel region. The ohmic contact layer 6127 is in ohmic contact with the semiconductor layer of type 6123 and the ohmic contact layer 6129 is in ohmic contact with the semiconductor layer of type 6125. For example, the ohmic contact layer 6127 may include AuTe or AuGe, and the 6129 ohmic contact layer can include AuBe or AuZn.
[0884] [0884] Referring to FIG. 108C, a 6130 insulation layer is formed on the first 6100 LED stack. The 6130 insulation layer has a multilayer structure and is standardized to have openings that expose the 6127 and 6129 ohmic contact layers. The 6130 insulation layer can include a first insulation layer 6131 and a second insulation layer 6135 and may also include a distributed Bragg reflector 6133. The second insulation layer 6135 may be incorporated into the reflector of
[0885] [0885] The first insulation layer 6131 may include, for example, a silicon nitride film, and the second insulation layer 6135 may include a silicon oxide film. The silicon nitride film exhibits good adhesion properties to the AlGaInP-based semiconductor layer, but the silicon oxide film has low adhesion properties to the AlGaInP-based semiconductor layer. The silicon oxide film has good adhesion to the first adhesive layer 6141, which will be described below, while the silicon nitride film has poor adhesion properties to the first adhesive layer 6141. Like the silicon nitride film and the oxide film of silicon exhibit mutually complementary voltage characteristics, it is possible to improve the stability of the process using the silicon nitride film and the silicon oxide film together, thus preventing the occurrence of defects.
[0886] [0886] While the ohmic contact layers 6127 and 6129 are described as being formed first and the insulation layer 6130 is formed from then on, according to some exemplary embodiments, the insulation layer 6130 can be formed first and the layers in ohmic contact 6127 and 6129 can be formed in the openings of the insulation layer 6130 which expose the semiconductor layer of type 6123 and the semiconductor layer of type 6125.
[0887] [0887] Referring to FIG. 108D, subsequently, the first electrode pads 6137, 6138, 6139 and 6140 are formed. The first electrode pads 6137 and 6139 are connected to the ohmic contact layers 6127 and 6129 through the openings of the 6130 insulation layer, respectively. The first pads of electrodes 6138 and 6140 are disposed in the insulation layer 6130 and are isolated from the first battery of LED 6100. As described below, the first electrodes 6138 and 6140 will be electrically connected to the semiconductor layers of type 6225 and 6325 of the second 6200 LED battery and the third 6300 LED battery, respectively. The first electrode pads 6137, 6138, 6139 and 6140 may have a multilayer structure and, in particular, may include a metal barrier layer on their upper surface.
[0888] [0888] Referring to FIG. 108E, a first adhesive layer 6141 is then formed on the first electrode pads 6137, 6138, 6139 and 6140. The first adhesive layer 6141 can contact the second insulation layer 6135.
[0889] [0889] The first adhesive layer 6141 is standardized to have openings that expose the first electrode pads 6137, 6138, 6139 and 6140. As such, the first adhesive layer 6141 is formed by a material that can be standardized and can be formed, for example, by epoxy, polyimide, SU8, SOG, BCB or others.
[0890] [0890] Metal bonding materials 6143 that are substantially ball-shaped are formed in the openings of the first adhesive layer 6141. Metal bonding material 6143 can be formed, for example, by an Indian ball or a ball welding, such as AuSn, Sn or similar. Metal bonding materials 6143 that have substantially a ball shape may be substantially the same height as a surface of the first adhesive layer 6141 or higher than the surface of the first adhesive layer 6141. However, a volume of each material of metal bond may be less than a volume of the opening in the first adhesive layer 6141.
[0891] [0891] Referring to FIG. 109A, subsequently, the substrate
[0892] [0892] The substrate 6021 can be a glass substrate on which a thin film transistor is formed, a Si substrate on which a CMOS transistor is formed, or others, for activating the active matrix.
[0893] [0893] While the first electrodes 6137 and 6139 are shown as spaced from the ohmic contact layers 6127 and 6129, the first electrodes 6137 and 6139 are electrically connected to the ohmic contact layers 6127 and 6129 through the insulation layer 6130, respectively.
[0894] [0894] Although the first adhesive layer 6141 and metal bonding materials 6143 are described as being formed on the first side of substrate 6121, the first adhesive layer 6141 and metal bonding materials 6143 can be formed on the side of substrate 6021 or adhesive layers can be formed on the first side of substrate 6121 and on the side of substrate 6021, respectively, and these adhesive layers can be bonded together.
[0895] [0895] The metal bonding materials 6143 are pressed by these pads between the first electrode pads 6137, 6138, 6139 and 6140, and the electrode pads 6027, 6028, 6029 and 6030 on the substrate 6021 and thus the surfaces upper and lower are deformed to have a flat shape according to the shape of the electrode pads. Since the metal bonding materials 6143 are deformed in the openings of the first adhesive layer 6141, the metal bonding materials 6143 can substantially completely fill the openings of the first layer of adhesive 6141 to be in close contact with the first layer of adhesive 6141, or an empty space can be formed in the openings of the first adhesive layer 6141. The first adhesive layer 6141 can contract in a vertical direction and can expand in the horizontal direction under heating and pressurizing conditions, and thus a shape of a wall opening of the openings may be deformed.
[0896] [0896] The shapes of the metal connecting elements 6143 and the first adhesive layer 6141 are described below with reference to FIGS. 115A, 115B and 115C.
[0897] [0897] Referring to FIG. 109B, the first substrate 6121 is removed and the semiconductor layer type n 6123 is exposed. The first 6121 substrate can be removed using a wet etching technique or the like. A surface roughened by surface texturing can be formed on the surface of the exposed 612 semiconductor layer.
[0898] [0898] Referring to FIG. 109C, the H1 holes that pass through the first LED stack 6100 and the insulation layer 6130 can be formed using a rigid mask or the like. The H1 holes can expose the first electrodes 6137, 6138 and 6140, respectively. The H1 hole is not formed in the first 6139 electrode pad and therefore the first 6139 electrode pad is not exposed through the first 6100 LED stack.
[0899] [0899] Next, a 6153 insulation layer is formed to cover the surface of the first 6100 LED stack and the side walls of the H1 holes. The insulation layer 6153 is standardized to expose the first pads of electrodes 6137, 6138,
[0900] [0900] Referring to FIG. 109D, the first connectors 6157, 6158 and 6160 which are electrically connected to the first electrode pads 6137, 6138 and 6140 through holes H1, respectively, are formed.
[0901] [0901] The first connector 1 6157 is connected to the first pad of electrodes 6137, the first connector 2 6158 is connected to the first pad of electrodes 6138 and the first connector 3 6160 is connected to the first pad of electrodes 6140. The first pad of electrodes 6140 is electrically connected to the n 6123 type semiconductor layer of the first 6100 LED stack and therefore the first 6157 connector is also electrically connected to the n 6123 type semiconductor layer. The first 2 6158 connector and the first 6160 3 connector are isolated electrically from the first 6100 LED battery.
[0902] [0902] Referring to FIG. 109E, a second adhesive layer 6161 is then formed on the first connectors 6157, 6158 and 6160. The second adhesive layer 6161 can contact the insulation layer 6153.
[0903] [0903] The second adhesive layer 6161 is patterned to have openings that expose the first connectors 6157, 6158 and 6160. As such, the second adhesive layer 6161 is formed by a material that can be patterned in a similar way to the first adhesive layer 6141 and it can be formed by, for example, epoxy, polyimide, SU8, SOG, BCB or others.
[0904] [0904] Metal bonding materials 6163 having substantially a ball shape are formed in the openings of the second adhesive layer 6161. The material and shape of the metal bonding material 6163 are similar to those of the metal bonding material 6143 described above and therefore detailed descriptions of it are omitted.
[0905] [0905] Referring to FIG. 110A, the second LED stack 6200 is grown on a second substrate 6221 and a second transparent electrode 6229 is formed on the second LED stack 6200.
[0906] [0906] The second substrate 6221 can be a substrate capable of increasing the second stack of LED 6200, for example, a sapphire substrate or a GaAs substrate.
[0907] [0907] The second 6200 LED stack can be formed from semiconductor layers based on AlGaInP or semiconductor layers based on AlGaInN. The second LED stack 6200 may include a semiconductor layer type n 6223, a semiconductor layer type p 6225 and an active layer, and the active layer may have a multi-quantum well structure. A composition ratio of the well layer to the active layer can be determined so that the second 6200 LED stack emits green light, for example.
[0908] [0908] The second transparent electrode 6229 is in ohmic contact with the p-type semiconductor layer. The second transparent electrode 6229 can be formed by a metal layer or a conductive oxide layer that is transparent to red light and green light. Examples of the conductive oxide layer can include SnO2, InO2, ITO, ZnO, IZO or others.
[0909] [0909] Referring to FIG. 110B, the second transparent electrode 6229, the semiconductor layer type p 6225 and the active layer are standardized to partially expose the semiconductor layer type n 6223. The semiconductor layer type n 6223 will be exposed in a plurality of regions corresponding to a plurality of pixel regions on the second substrate 6221.
[0910] [0910] Although the semiconductor type n 6223 layer is described as being exposed after the formation of the second transparent electrode 6229, in some exemplary embodiments, the semiconductor type n 6223 can be exposed first and the second transparent electrode 6229 can be formed posteriorly.
[0911] [0911] Referring to FIG. 110C, a first 6230 color filter is formed on the second transparent electrode 6229. The first 6230 color filter is formed to transmit light generated in the first 6100 LED stack and to reflect the light generated in the second 6200 LED stack.
[0912] [0912] Then, an insulation layer 6231 can be formed on the first color filter 6230. The insulation layer 6231 can be formed to control stress and can be formed, for example, by a silicon nitride film (SiNx) or a silicon oxide (SiO2) film. Insulation layer 6231 can be formed first before forming the first color filter
[0913] [0913] The openings that expose the type 6 semiconductor layer 6223 and the second transparent electrode 6229 are formed by standardizing the insulation layer 6231 and the first color filter 6230.
[0914] [0914] Although the first 6230 color filter is described as being formed after the n 6223 type semiconductor layer is exposed, according to some exemplary embodiments, the first 6230 color filter can be formed first and then the first color filter 6230, the second transparent electrode 6229, the semiconductor layer type p 6225 and the active layer can be standardized to expose the semiconductor layer type n 6223. Then, the insulation layer 6231 can be formed to cover side surfaces of the semiconductor layer type p 6225 and the active layer.
[0915] [0915] Referring to FIG. 110D, subsequently, the second electrode pads 6237, 6238 and 6240 are formed on the first color filter 6230 or on the insulation layer 6231. The second electrode pad 6237 can be electrically connected to the semiconductor layer type n 6223 by opening the the first color filter 6230 and the second electrode pad 6238 can be electrically connected to the second transparent electrode 6229 through the opening of the first color filter 6230. The second electrode pad 6240 is arranged on the first color filter 6240 and is isolated from the second 6200 LED battery.
[0916] [0916] Referring to FIG. 111A, the second LED stack 6200 and the second electrode pads 6237, 6238 and 6240 which are described with reference to FIG. 110D, are coupled to the second adhesive layer 6161 and to the metal bonding materials 6163 which are described with reference to FIG. 109E. Metal bonding materials 6163 can connect the first connectors 6157, 6158 and 6160 and the second electrodes 6237, 6238 and 6240, respectively, and the second adhesive layer 6161 can connect insulation layer 6231 and insulation layer 6153. A bonding using second adhesive layer 6161 and metal bonding materials 6163 is similar to that described with reference to FIG. 109A and therefore its detailed description is omitted.
[0917] [0917] The second substrate 6221 is separated from the second stack of LED 6200 and the surface of the second stack of LED 6200 is exposed. The second substrate 6221 can be separated using a technique such as chemical engraving, laser lifting or the like. A rough surface by surface texturing can be formed on the surface of the exposed second LED stack 6200, that is, the surface of the n 6223 type semiconductor layer.
[0918] [0918] Although the second adhesive layer 6161 and the metal bonding materials 6163 are described as being formed in the first stack of LED 6100 to connect the second stack of LED 6200, according to some exemplary embodiments, the second layer of adhesive 6161 and metal bonding materials 6163 can be formed on the second side of the LED stack
[0919] [0919] Referring to FIG. 111B, the H2 holes that pass through the second LED stack 6200, the second transparent electrode 6229, the first color filter 6230 and the insulation layer 6231 can be formed using a rigid mask or the like. H2 holes can expose second electrode pads 6237 and 6240, respectively. The H2 hole is not formed in the second electrode pad 238 and therefore the second electrode pad 238 is not exposed through the second LED stack 6200.
[0920] [0920] Next, an insulating layer 6253 is formed to cover the surface of the second stack of LED 6200 and the side walls of the H2 holes. The insulation layer 6253 is standardized to expose the second electrode pads 6237 and 6240 in the H2 holes. The insulation layer 6253 may include a silicon nitride film or a silicon oxide film.
[0921] [0921] Referring to FIG. 111C, second connectors 6257 and 6260 that are electrically connected to the second electrodes 6237 and 6240 through holes H2, respectively, are formed. The second connector 1 6257 is connected to the second electrode 6237 and therefore electrically connected to the semiconductor layer of type n 6223. The second connector 2 6260 is isolated from the second battery of LED 6200 and isolated from the first battery of LED 6100.
[0922] [0922] In addition, the second connector 1 6257 is electrically connected to the electrode pad 6027 through the first connector 1 6157 and the second connector 2 6260 is electrically connected to the electrode pad 6030 through the first connector 3 6160. The second connector 1 6257 can be stacked in a vertical direction to the first connector 1 6157 and the second connector 2 6260 can be stacked in a vertical direction to the first connector 3 6160. However, the inventive concepts are not limited to these.
[0923] [0923] Referring to FIG. 111D, a third adhesive layer 6261 is then formed on the second connectors 6257 and 6260. The third adhesive layer 6261 can contact the insulation layer 6253.
[0924] [0924] The third adhesive layer 6261 is standardized to have openings that expose the second connectors 6257 and 6260. As such, the third adhesive layer 6261 is formed by a material that can be patterned in a similar way to the first adhesive layer 6141 and can be formed by, for example, epoxy, polyimide, SU8, SOG, BCB or others.
[0925] [0925] Metal bonding materials 6263 which are substantially ball-shaped are formed in the openings of the third adhesive layer 6261. The material and shape of the metal bonding material 6263 are similar to those of the metal bonding material 6143 described above and therefore detailed descriptions of it are omitted.
[0926] [0926] Referring to FIG. 112A, the third 6300 LED stack is grown on a third 6321 substrate and a third transparent 6329 electrode is formed on the third 6300 LED stack.
[0927] [0927] The third substrate 6321 can be a substrate capable of growing the third stack of LED 6300, for example, a sapphire substrate. The third 6300 LED stack can be formed by layers of semiconductors based on AlGaInN. The third 6300 LED stack can include a n 6323 type semiconductor layer, a p 6325 type semiconductor layer and an active layer, and the active layer can have a multi-quantum well structure. A composition ratio of the well layer to the active layer can be determined so that the third 6300 LED stack emits blue light, for example.
[0928] [0928] The third transparent electrode 6329 is in ohmic contact with the semiconductor type p 6325. The third transparent electrode 6329 can be formed by a metal layer or a layer of conductive oxide that is transparent to red light, green light and blue light. Examples of the conductive oxide layer can include SnO2, InO2, ITO, ZnO, IZO or others.
[0929] [0929] Referring to FIG. 112B, the third transparent electrode 6329, the p 6325 semiconductor layer and the active layer are standardized to partially expose the n 6323 semiconductor layer. The n 6323 semiconductor layer will be exposed in a plurality of regions corresponding to a plurality of pixel regions on the third substrate 6321.
[0930] [0930] Although the semiconductor layer of type 6323 is described as exposed after the formation of the third transparent electrode 6329, according to some exemplary embodiments, the semiconductor layer of type 6323 can be exposed before the first and the third transparent electrode 6329 can be formed.
[0931] [0931] Referring to FIG. 112C, a second 6330 color filter is formed on the third transparent electrode 6329. The second 6330 color filter is formed to transmit light generated in the first 6100 LED stack and the second 6200 LED stack and to reflect the light generated in the third stack 6300 LED.
[0932] [0932] Then, an insulation layer 6331 can be formed on the second color filter 6330. The insulation layer 6331 can be formed to control stress and can be formed, for example, by a silicon nitride film (SiNx) or a silicon oxide (SiO2) film. The insulation layer 6331 can be formed first before the formation of the second color filter 6330. Meanwhile, openings that expose the type 6 semiconductor layer 6323 and the second transparent electrode 6329 are formed by standardizing the insulation layer 6331 and the second filter of color 6330.
[0933] [0933] Although the second color filter 6330 is described as being formed after the semiconductor layer type 6323 is exposed, according to some exemplary embodiments, the second color filter 6330 can be formed first and the second color filter 6330 , the third transparent electrode 6329, the semiconductor layer type p 6325 and the active layer can be standardized to expose the semiconductor layer type n 6323 later. Then, the insulating layer 6331 can be formed to cover side surfaces of the type 6325 semiconductor layer and the active layer.
[0934] [0934] Referring to FIG. 112D, subsequently, the third electrode pads 6337 and 6340 are formed in the second color filter 6330 or in the insulation layer 6331. The third electrode pad 6337 can be electrically connected to the semiconductor layer type n 6323 by opening the second filter color 6330 and the third electrode pad 6340 can be electrically connected to the third transparent electrode 6329 through the opening of the second color filter 6330.
[0935] [0935] Referring to FIG. 113A, the third 6300 LED stack and the third electrode pads 6337 and 6340 which are described with reference to FIG. 112D, are attached to the third adhesive layer 6261 by the metal bonding materials 6263 which are described with reference to FIG. 111E. The metal connection materials 6263 can connect the second connectors 6257 and 6260 and the third electrodes 6337 and 6340, respectively, and the third adhesive layer 6261 can connect the insulation layer 6331 and the insulation layer 6253. The connection using the third adhesive layer 6261 and metal bonding materials 6263 is similar to that described with reference to FIG. 109A and therefore their detailed descriptions are omitted.
[0936] [0936] The third substrate 6321 is separated from the third 6300 LED stack and the surface of the third 6300 LED stack is exposed. The third 6321 substrate can be separated using a technique such as laser lifting, chemical lifting or others. A rough surface by surface texturing can be formed on the surface of the third exposed 6300 LED stack, that is, the surface of the n 6323 type semiconductor layer.
[0937] [0937] Although the third adhesive layer 6261 and the metal bonding materials 6263 are described as being formed in the second stack of LED 6200 to connect the third stack of LED 6300, according to some exemplary embodiments, the third layer of adhesive 6261 and metal bonding materials 6263 can be formed on the third side of the LED stack
[0938] [0938] Referring to FIG. 113B, subsequently, the regions between adjacent pixels are then recorded to separate the pixels, and an insulating layer 6341 can be formed. The insulating layer 6341 can cover a side surface and an upper surface of each pixel. A region between adjacent pixels can be removed to expose the substrate 6021, but the inventive concepts are not limited to these. For example, the first adhesive layer 6141 can be formed continuously over a plurality of pixel regions without being separated, and the insulation layer 6130 can also be continuous.
[0939] [0939] Referring to FIG. 114, subsequently, a 6350 barrier can be formed in a region of separation between the pixel regions. The 6350 barrier can be formed by a light reflecting layer or a light absorbing layer and, therefore, light interference between pixels can be avoided. The light reflecting layer may include, for example, a white PSR, a distributed Bragg reflector, an insulation layer such as SiO2 and a reflective metal layer deposited on it, or a highly reflective organic layer. For a light blocking layer, black epoxy, for example, can be used.
[0940] [0940] Thus, a display device according to an exemplary embodiment, in which a plurality of pixels are arranged on the substrate 6021, can be provided. The first to the third batteries of LED 6100, 6200 and 6300 in each pixel can be triggered independently by the input of energy through the pads of electrodes 6027, 6028, 6029 and 6030.
[0941] [0941] FIGS. 115A, 115B and 115C are schematic cross-sectional views of metal bonding materials 6143, 6163 and
[0942] [0942] Referring to FIG. 115A, metal bonding materials 6143, 6163 and 6263 are arranged in the openings in the first to third adhesive layers 6141, 6161 and 6261. A lower surface of the metal bonding materials 6143, 6163 and 6263 is in contact with the electrodes 6030 or connector 6160 or 6260 and therefore metal bonding materials 6143, 6163 and 6263 can have a substantially flat shape depending on a shape of the upper surface of the electrode pads or connectors. The upper surfaces of the metal bonding materials 6143, 6163 and 6263 can be substantially flat in shape, depending on the shape of the electrode pads 6140, 6240 and
[0943] [0943] An inner wall of the openings of adhesive layers 6141, 6161 and 6261 can also be substantially convex in shape into the openings, and the side surfaces of the metal bonding materials 6143, 6163 and 6263 may be in contact with side surfaces of adhesive layers 6141, 6161 and 6261. However, if the volume of metal bonding materials 6143, 6163 and 6263 is less than the volume of the openings of adhesive layers 6141, 6161 and 6261, an empty space can be formed in the openings , as shown.
[0944] [0944] Referring to FIG. 115B, the shapes of the metal bonding materials 6143, 6163 and 6263 and the adhesive layers 6141, 6161 and 6261, according to an exemplary embodiment, are substantially similar to those described with reference to FIG.
[0945] [0945] Referring to FIG. 115C, the shapes of the metal bonding materials 6143, 6163 and 6263, according to an exemplary embodiment, are similar to those described with reference to FIG. 121B, but are different from the shapes of the inner walls of the openings of the adhesive layers 6141, 6161 and 6261. In particular, the inner wall of the opening can be formed to be concave by the metal bonding material.
[0946] [0946] Although certain exemplary modalities and implementations have been described here, other modalities and modifications will be evident from this description. Therefore, the inventive concepts are not limited to these modalities, but to the broader scope of the appended claims and to several obvious modifications and equivalent arrangements, as would be evident to a person skilled in the art.

权利要求:
Claims (20)
[1]
1. Light emitting device, characterized by comprising a first LED subunit; a second LED subunit positioned adjacent the first LED subunit; a third LED subunit disposed adjacent to the second LED subunit; electrode pads arranged in the first LED subunit and electrically connected to the first, second and third LED subunits, the electrode pads comprise a common electrode pad electrically connected to each of the first, second and third LED subunits, and first, second and third electrode pads connected to one of the first, second and third LED subunits; and a first reflective electrode disposed between the electrode pads and the first LED subunit, in which the common electrode pad, the second electrode pad and the third electrode pad are electrically connected to the second LED subunit and the third LED subunit. LED through holes that pass through the first LED subunit; the first LED subunit, the second LED subunit and the third LED subunit are configured to operate independently; the light generated in the first LED subunit is configured to be emitted to the outside of the light emitting device through the second LED subunit and the third LED subunit; and the light generated in the second LED subunit is configured to be emitted to the outside of the light emitting device through the third LED subunit.
[2]
2. Light-emitting device according to claim 1, characterized in that the first, second and third LED subunits comprise a first LED battery, a second LED battery and a third LED battery, respectively; and the first, second and third LED batteries are configured to emit red light, green light and blue light, respectively.
[3]
3. Light-emitting device according to claim 1, characterized in that the first reflective electrode is disposed between the electrode pads and the first LED subunit and in ohmic contact with the first LED subunit, in which the common electrode pad is connected to the first reflector electrode.
[4]
4. Light-emitting device according to claim 3, characterized in that the first reflecting electrode comprises an ohmic contact layer in ohmic contact with an upper surface of the first LED subunit and a reflective layer that covers the layer in ohmic contact.
[5]
Light-emitting device according to claim 4, characterized in that the first reflecting electrode has a hollow portion defined by an element in substantially annular shape; and the common electrode pad passes through the substantially annular hollow portion of the element.
[6]
6. Light-emitting device according to claim 4, characterized in that it further comprises a second transparent electrode interposed between the second LED subunit and the third LED subunit and in ohmic contact with a lower surface of the second LED subunit; and a third transparent electrode in ohmic contact with an upper surface of the third LED subunit, where the common electrode pad is electrically connected to the second transparent electrode and the third transparent electrode.
[7]
7. Light-emitting device according to claim 6, characterized in that the common electrode pad is connected to an upper surface of the second transparent electrode and to an upper surface of the third transparent electrode.
[8]
Light-emitting device according to claim 7, characterized in that each of the first LED subunit and the third LED subunit comprises a first conductivity type semiconductor layer and a second conductivity type semiconductor layer arranged in a region partial of the first conductivity-type semiconductor layer; and the first electrode pad and the third electrode pad are electrically connected to the first conductivity type semiconductor layer of the first LED subunit and the third LED subunit, respectively.
[9]
Light emitting device according to claim 8, characterized in that it also comprises a first ohmic electrode disposed in the first conductivity type semiconductor layer of the first LED subunit, in which the first electrode pad is connected to the first ohmic electrode .
[10]
10. Light-emitting device according to claim 9, characterized in that the third electrode pad is directly connected to the first conductivity type semiconductor layer of the third LED subunit.
[11]
Light emitting device according to claim 8, further comprising: a first color filter disposed between the third transparent electrode and the second LED subunit; and a second color filter disposed between the first and the second LED subunit.
[12]
12. Light-emitting device according to claim 11, characterized in that the first color filter and the second color filter comprise insulation layers with different refractive indices.
[13]
13. Light-emitting device according to claim 11, characterized in that the first color filter and the second color filter comprise layers of insulation with different refractive indices.
[14]
Light emitting device according to claim 1, characterized in that it further comprises a substrate on which the third LED subunit is arranged.
[15]
15. Light-emitting device according to claim 14, characterized in that the substrate comprises a sapphire substrate or a gallium nitride substrate.
[16]
16. Light-emitting device according to claim 1, characterized by further comprising an insulation layer disposed between the first LED subunit and the electrode pads, in which the electrode pads are electrically connected to the first, second and third LED subunits through the insulation layer.
[17]
17. Light-emitting device according to claim 16, characterized in that the insulation layer comprises at least one of a distributed Bragg reflector and a light blocking material.
[18]
18. Light-emitting device according to claim 1, characterized in that the first LED subunit is configured to emit a red, green and blue light; the second LED subunit is configured to emit a light other than red, green and blue from the first LED subunit; and the third LED subunit is configured to emit a light other than red, green and blue from the first and second LED subunits.
[19]
19. Display device, characterized by comprising a circuit board; and a plurality of light-emitting devices arranged on the circuit board, at least some of the light-emitting devices comprise the light-emitting device according to claim 1, wherein the electrode pads are electrically connected to the circuit board.
[20]
20. Display device according to claim 19, characterized in that each of the light-emitting devices comprises a substrate coupled to the third LED subunit; and the substrates of the light-emitting devices are spaced apart from each other.

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法律状态:
2021-12-07| B350| Update of information on the portal [chapter 15.35 patent gazette]|

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