Photomask with a mask edge provided with a ring-shaped esd protection area

专利摘要:
The photomask 1 comprises a transmissive base plate 2 and a first side provided as a layer 4 of metallic mask material. In this layer, the mask pattern 5 is formed surrounded by an inner region 6 and an outer region 7 of the mask material, which are separated by a ring-shaped protective region 8. In this protective area, the protective pattern 9 is located in the inner and outer zone, with a track having an end 11 12 away from the zone, which is smaller than the minimum distance between the pattern portions present in the mask pattern 5. 10). Accordingly, the photomask is protected against electrostatic discharge which may damage the mask pattern.
公开号:KR20010040949A
申请号:KR1020007008872
申请日:1999-11-29
公开日:2001-05-15
发明作者:레이저스안토니우스에이엠
申请人:롤페스 요하네스 게라투스 알베르투스；코닌클리즈케 필립스 일렉트로닉스 엔.브이.；
IPC主号:

专利说明:

Photomask with mask edge with ring-shaped electrostatic discharge protection area {PHOTOMASK WITH A MASK EDGE PROVIDED WITH A RING-SHAPED ESD PROTECTION AREA}
The present invention relates to a photomask comprising a base plate of radiation-transmitting and electrically insulating material and a first side provided as a layer of electrically conductive mask material. The mask pattern to be imaged is formed surrounded by the inner and outer edges of the mask material, and both edges are electrically separated by ring-shaped protection regions, respectively.
Such photomasks can be used particularly suited for the manufacture of semiconductor devices and flat panel displays. In practice, the base plate is generally a quartz glass plate, and the layer of mask material generally contains chromium. The pattern of the mask is often imaged on a scaled down scale, for example on a photoresist layer provided on the metal layer. After exposure and development of the photoresist, the metal layer may be etched in the pattern of conductor tracks corresponding to the mask pattern. The photomask pattern to be imaged includes many closely spaced tracks of mask material that are sometimes connected to large areas of the mask material. The tracks correspond to conductor tracks to be formed in the metal layer, and the regions correspond to, for example, bond pads to be formed in the metal layer, which bond pads are used to contact the device to be manufactured.
The photomask has an edge of the conductive mask material separated by an inner edge and an outer edge that are electrically insulated from each other by a ring-shaped protective area. The ring-shaped protective region serves to protect the mask against damage caused by electro-static discharge that may occur in the mask pattern.
In operation, the mask pattern surrounded by the closed edges of the conductive mask material may be damaged by electrostatic discharge. The mask material present on the electrically insulating base plate may be electrically charged. This may be caused, for example, by friction or air flow caused by contact of clothing with other insulating materials. In order to be able to image the photomask onto the photoresist layer, the photomask is placed in a projector on a grounded mask holder. In this way the closed edges of the mask material present around the mask pattern are grounded. The voltage difference between the edge and the mask pattern can then develop, the magnitude of which is such that an electrical discharge appears in the mask pattern causing the above damage.
JP-A-5-100410 describes a photomask of the type mentioned at the outset, wherein the mask material is completely removed from the ring-shaped protective zone. As such, the empty ring-shaped protective region has a width in the range of 0.5-2 mm.
If the conductive mask material is electrically charged as described above, only the outer edges are grounded when the photomask is placed in the projector. If the empty protection region sufficiently insulates the outer edge and the inner edge from each other, the voltage difference between the inner edge and the mask pattern does not develop. In this way, electrostatic discharge, which can damage the mask pattern, is prevented. However, it has been found in practice that the charge present on the inner edges and the mask pattern can cause damage despite the presence of an empty ring-shaped protection zone.
It is an object of the present invention to provide a photomask having, among other things, sufficient electrostatic discharge protection. A feature of the photomask according to the present invention for achieving the above object includes a protective pattern in which a ring-shaped protective region is formed in a layer of mask material, wherein the protective pattern is present in the mask pattern while being located near an inner edge or an outer edge. It comprises a track having an end away from the inner edge or the outer edge less than the minimum distance between the pattern portions.
When the conductive mask material is electrically charged and the outer edge is grounded as a result, the voltage between the protective pattern, the inner edge and the mask pattern develops from the outer edge and the structure enclosed by it, ie from the outer edge towards the center. . The protective pattern is more fragile than the mask pattern because the protective region comprises conductive tracks of the protective pattern located very close to the inner and outer edges. The distance is smaller than the distance between the mask pattern portions. That is, when the distance between mask pattern parts is 1 micrometer, the distance is 0.8 micrometer as an example. Since the charge present in the photomask is at least substantially removed, damage to the mask pattern due to electrostatic discharge is prevented. However, it has been found that the protective pattern can be locally damaged, in which case the mask material is sputtered off so that no short circuit occurs between the outer and inner edges. If a subsequent electrostatic discharge occurs, the undamaged portion of the protective pattern located after the damaged portion assumes the protective function of the mask pattern. Only after the damage of the protection pattern due to a large discharge increases, the protection pattern will cease to function. In practice, however, it does not reach this state.
If the track has a width at the position of the end located near the inner edge or outer edge, more robust protection is obtained, which is smaller than the width of the narrowest mask track present in the mask pattern, for example, If it is 1 micrometer, a 1st width is 0.8 micrometer. The electric field between the edge and the adjacent end of the track of the protective pattern is then greater than the electric field between the track and the mask pattern at the same voltage.
The track is preferably connected to an area of the mask material included in the protective pattern as an end located near the inner edge or the outer edge. If the photomask comprises a protective pattern with areas and the same protective pattern that does not yet have a charged area in a similar manner, the outer edges are grounded, for example, in the flow of ionized air so that the electrostatic discharge is protected by the latter. It appears faster in the protective pattern of the former than in the pattern.
The mask pattern may also include relatively large areas, such as the bond pads described above. In unprotected photomasks, it has been found that damage due to electrostatic discharge appears relatively easily near the relatively large areas described above. In order to ensure that the protection pattern also provides sufficient protection against the damage, the area connected to the track having an end located near the inner edge or the outer edge is a surface area larger than the surface area of the maximum mask area present in the mask pattern. Has This and the relatively small width of the tracks connected to the protective pattern are responsible for the fact that the protective pattern is more susceptible to electrostatic discharge than the mask pattern.
An area connected to a track having an end located near an inner edge or an outer edge is located near another area included in the protective pattern, and has an end away from the area that is smaller than the minimum distance between the pattern portions present in the mask pattern. It is preferable to connect to another track. As a result, discharge can appear in the pattern without causing serious damage to the protective pattern. For the same reason as described above, the width of another track is preferably smaller than the width of the minimum width mask track present in the mask pattern, and the surface area of another area is larger than the surface area of the maximum mask area present in the mask pattern. It is desirable to be large.
If all areas as well as all tracks in the protection pattern are the same, a simple pattern is obtained.
The best protection is obtained when the protection pattern fills the entire ring-shaped protection area. In this case, the charge present on the portion of the photomask located inside the outer edge can be discharged to the outer edge without bypass in all directions.
These and other aspects of the invention will be apparent from the description with reference to the embodiments described below.
1 is a schematic plan view of a photomask according to the present invention;
FIG. 2 is a schematic cross-sectional view of the photomask shown in FIG. 1;
3 is a schematic diagram of several protective patterns that can be used in the photomasks shown in FIGS. 1 and 2;
4 is a schematic diagram of one embodiment of a protective pattern that can be used in the photomasks shown in FIGS. 1 and 2;
The drawings are not to scale, like reference numerals designate like parts.
FIG. 1 is a plan view of a photomask 1 comprising a base plate 2 which is radiation transmissive and electrically insulating, in this example typically quartz glass having a thickness of about 100 nm, and FIG. 2 is a cross-sectional view thereof. The first side 3 of the base plate 2 has a layer of electrically conductive mask material. In this example, the mask material is a layer typically about 100 nm thick whose surface has an antireflective layer (not shown) of chromium oxide. The mask pattern 5 to be imaged is formed in the layer 4 of the mask material. This pattern is surrounded by an inner edge 6 and an outer edge 7 of the mask material which are electrically insulated from each other by the ring-shaped protective region 8.
The mask pattern 5 is often imaged on a reduced scale, for example in a photorest layer applied to the metal layer. After exposure and development of the photoresist, the metal layer is etched in the pattern of conductor tracks corresponding to the mask pattern. The photomask pattern to be imaged contains many densely spaced tracks of mask material, which are not shown in the figures, and are also sometimes connected to large areas of the mask material, which are also not shown in the figures. The tracks correspond to conductor tracks to be formed in the metal layer, and the regions correspond to bond pads as examples to be formed in the metal layer, which bond pads are used to contact the device to be manufactured.
The photomask has edges 6 and 7 of conductive mask material, which are separated into an inner edge 6 and an outer edge 7 which are electrically insulated from each other by ring-shaped protective zones 8. . This ring-shaped protective region is used to protect the photomask from damage due to electrostatic discharge that may occur in the mask pattern 5.
A ring-shaped protective region 8 is formed in the layer 4 of the mask material and is located near the inner edge 6 and the outer edge 7 and is present in the pattern portion (not shown) in the mask pattern 5. Protection pattern 9 comprising a track 10 having an end 11 away from the edge (denoted by reference numeral 12) less than the minimum distance between
When the conductive mask material 4 is electrically charged and the outer edge 7 is subsequently grounded, the structure and the exterior encircled by the center, the protective pattern 9, the inner edge 6 and the mask pattern 5 from the edges. The voltage between the edges 7 develops. The protective pattern 9 is more than the mask pattern 5 because the protective region 8 comprises a conductive track 11 of the protective pattern 9 located very close to the outer edge 7 and the inner edge 6. weak. The distance is smaller than the distance between parts of the mask pattern. That is, when the distance between parts of a mask pattern is 1 micrometer as an example, the distance is 0.8 micrometer. This is the reason why the electrostatic discharge appears in the protective pattern 9 when the voltage is high enough. This can damage the protective pattern 9 locally, but the mask pattern 5 remains undamaged. Since at least most of the electric charges present in the photomask 1 are removed, damage to the mask pattern 5 due to electrostatic discharge is prevented.
The first width when the track 10 is smaller than the width of the minimum width mask track present in the mask pattern, i.e. the second width is 1 占 퐉, in which the widths near the inner edge 6 and outer edge 7 are present in the mask pattern. If it has an end of 0.8 mu m, more robust protection is obtained. The electric field between the end and the edge of the track of the protective pattern whose end is located close to the edge will be greater than the electric field between the track of the mask pattern at the same voltage.
The track 10 is an area 13 of mask material included in the protective pattern 8 as an end 11 located near the inner edge 6 and the outer edge 7, as shown on the right side of FIGS. 3 and 4. Is preferably connected to. If the photomask 1 comprises a protective pattern 8 with a region 13 and the same protective pattern 8 does not yet have a charged region in a similar manner, the outer edge 7 is an example. As a result, grounded in the flow of ionized air, electrostatic discharge appears faster in the former's protective pattern than in the latter protective pattern.
The mask pattern 5 will practically also include a relatively large area of 100 μm in length and width as an example, such as the bond pad described above. It has been found that the unprotected photomask is easily damaged near the above relatively large area and also by electrostatic discharge. In order to ensure that the protective pattern 8 also provides sufficient protection against the damage, the area connected to the track 10 with the end 11 located near the inner edge 6 or the outer edge 7 is It has a surface area larger than the surface area of the maximum mask area present in the mask pattern. The length and width of this region are, for example, 200 mu m. This and the relatively small width of the track 10 connected to the protective pattern make the protective pattern more susceptible to electrostatic discharge than the mask pattern 5.
As shown in FIG. 4, located near another area 16 included in the protective pattern, away from the area less than the minimum distance between the pattern portions present in the mask pattern 5 (indicated by reference numeral 17). Region 13 is preferably connected to another track 14 having an end 15. As a result, electrostatic discharge can appear in the protective pattern without causing serious damage to the protective pattern 8. For the same reason as described above, the width of another track 14 is preferably smaller than the width of the mask track of the minimum width present in the mask pattern, and the surface area of another area 16 is the maximum present in the mask pattern. It is preferred to be larger than the surface area of the mask area.
If all the tracks 11, 15 as well as all the areas 13, 16 in the protection pattern are the same, a simple pattern is obtained.
The best protection is obtained when the protection pattern 9 fills the entire ring-shaped protection area 8 as shown in FIG. 1. In this case, the charge present on the portions 8, 6, 5 of the photomask 1 located inside the outer edge 7 can be discharged to the outer edge 7 without bypass in all directions. In the example shown in FIG. 4, the regions 13 and 16 are 200 μm in length and width, the tracks 11 and 14 are 49 μm in length and 2 μm in width, and the distances 12 and 17 are 1 μm. to be. The protection pattern shown in FIG. 4 is used to protect the photomask employed in fabricating a semiconductor circuit having a minimum distance of 1 μm and a minimum dimension. The photomask is reduced by a factor of 5 during projection so that the minimum dimension in the mask pattern is 55 μm.

权利要求:
Claims (8)
[1" claim-type="Currently amended] A photomask comprising a base plate of radiation-transmitting and electrically insulating material and a first side provided formed of a layer of electrically conductive mask material, wherein the mask pattern to be imaged is formed with an inner edge and an outer edge of the mask material. In the photomask is formed surrounded by the edge, the edge is electrically separated from each other by a ring-shaped protection region,
A ring-shaped protective region includes a protective pattern formed in the layer of mask material, the protective pattern being located near the inner edge or outer edge, and from the inner edge or outer edge less than the minimum distance between the pattern portions present in the mask pattern. Photomask that contains tracks that have fallen away
[2" claim-type="Currently amended] The method of claim 1,
And the track has a width less than the width of the minimum width mask track present in the mask pattern at a location at an end located near an inner edge or an outer edge.
[3" claim-type="Currently amended] The method according to claim 1 or 2,
The track is connected to an area of the mask material included in the protective pattern as an end located near an inner edge or an outer edge.
[4" claim-type="Currently amended] The method of claim 3, wherein
A photomask having a surface area larger than the surface area of the maximum mask area present in the mask pattern, wherein the area connected to the track having an end located near the inner edge or outer edge.
[5" claim-type="Currently amended] The method of claim 4, wherein
An area connected to a track having an end located near an inner edge or an outer edge is located near another area included in the protective pattern, with an end away from the area less than the minimum distance between the pattern portions present in the mask pattern. Photomask connected to another track.
[6" claim-type="Currently amended] The method of claim 5,
The width of another track is less than the width of the minimum width mask track present in the mask pattern, and the surface area of another area is larger than the surface area of the maximum mask area present in the mask pattern.
[7" claim-type="Currently amended] The method according to any one of claims 3 to 6,
All tracks as well as all areas in the protection pattern are the same photomask.
[8" claim-type="Currently amended] The method according to any one of claims 1 to 7,
The protective pattern is a photomask that fills the entire ring-shaped protective area.

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同族专利:

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公开号 | 公开日

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WO2000036468A1|2000-06-22|

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EP1055153A1|2000-11-29|

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KR100633883B1|2006-10-16|

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EP1055153B1|2012-01-18|

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JP2002532758A|2002-10-02|

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US6291114B1|2001-09-18|

引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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法律状态:
1998-12-14|Priority to EP98204223.6

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1998-12-14|Priority to EP98204223

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1999-11-29|Application filed by 롤페스 요하네스 게라투스 알베르투스, 코닌클리즈케 필립스 일렉트로닉스 엔.브이.

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2001-05-15|Publication of KR20010040949A

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2006-10-16|Application granted

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2006-10-16|Publication of KR100633883B1

优先权:

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申请号 | 申请日 | 专利标题

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EP98204223.6|1998-12-14|

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EP98204223|1998-12-14|