• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    An oxide film was formed on the BST layer by BST (Ba 1-X Sr x TiO 3 ) etching method using an Ar / Cl 2 gas system and the BST layer was exposed in a certain region by patterning. Then, Ar / Cl 2 / SF 6 gas By using the system as etchant and etching the exposed BST layer using a low pressure, high density ICP (Inductively Coupled Plasma) method, it is possible to improve the etching ratio of BST and the selectivity to the mask and to remove residues and byproducts.
    公开号:KR19980054364A
    申请号:KR1019960073512
    申请日:1996-12-27
    公开日:1998-09-25
    发明作者:이헌민
    申请人:구자홍；엘지전자 주식회사；
    IPC主号:
    专利说明:

    BST etch method
    The present invention relates to a BST (Ba 1-X Sr x TiO 3 ) etching method, and more particularly, to a BST etching method using an Ar / Cl 2 gas system.
    Generally, it is necessary to develop a new dielectric with higher permittivity so as to maintain the required charge storage density (25-30 fF / cell) even in a smaller area in order to develop the next generation of highly integrated Gbit scale DRAM Do.
    At present, materials such as Ta 2 O 5 (ε r = 20-25) and high dielectric materials (ε r = 100-1500) are widely used as substitutes for Si 3 N 4 used in 16 Mbit and 64 Mbit DRAM Has come.
    In particular, SrTiO 3 and Ba 1 -X Sr x TiO 3 among the high-k materials are highly stable both chemically and thermally without losing their high dielectric constant at high frequencies above 10 GHz, making them suitable dielectric materials for making Gbit-scale DRAMs It has been thought.
    In order to apply these materials to the device, it is necessary to improve the physical and electrical properties of the material related to the characteristics of the device, to simplify the structure of the device as much as possible, to develop a dry etching process of such a high- It has a lot of technical problems to be solved.
    In order to improve the electrical characteristics and increase the degree of integration in the application of the high-k material to the DRAM, it is necessary to dry-etch the high-dielectric material.
    In this regard, recently, a high - k material such as Pb (Zr 1 -x Ti x ) O 3 or SrTiO 3 , or an electrode material such as Pt or RuO 2 is dry-etched using Cl 2 as a main etchant There are reports on the process.
    As a conventional technique for BST etching, there is known a method in which a gas system such as CF 4 , SF 6 , Cl 2 , HBr, and Ar is used as an etchant and etching is performed using a MERIE (Magnetically Enhanced Reactive Ion Etching) method .
    The MERIE method uses a magnet to form a magnetic field in a chamber to help generate plasma. The MERIE method is characterized in that ions and electrons in the plasma have a large kinetic energy in a direction perpendicular to the magnetic field .
    When BST is etched in this way, it is best to obtain an etching rate of 250 Å / min in the Ar / CF 4 gas system and a selectivity ratio of 0.23 in the Ar / Cl 2 gas system using SiO 2 as the mask Results.
    Particularly, when BST is etched by the MERIE etching method using the Ar / Cl 2 gas system, the etching is very inefficient and the residues or by-products of the Cl system are formed after the etching have.
    These products are not volatile under the etching conditions, and thus have a further problem in that a process of removing these products after etching is added.
    The conventional BST etching method has the following problems.
    First, the etching is inefficient and the process is complicated because residues or by-products generated after etching must be removed.
    Second, contamination of the chamber occurs due to by-product formation and by-product removal process.
    It is an object of the present invention to provide a BST etching method capable of improving an etching rate and removing by-products generated during etching.
    BRIEF DESCRIPTION OF THE DRAWINGS FIGURES 1A-1D illustrate a BST etch process in accordance with the present invention.
    Fig. 2 schematically shows an apparatus for generating an ICP (Inductively Coupled Plasma) source; Fig.
    FIG. 3 is a graph showing the etch rate of BST and selectivity of oxide film and BST according to ICP power.
    4 is a graph showing the etching rate of BST and the selectivity of oxide film and BST according to the pressure.
    5A is a photograph showing a state after BST is etched by a method according to the prior art.
    FIG. 5B is a photograph showing the BST after etching according to the method of the present invention. FIG.
    Description of the Related Art [0002]
    1: substrate 2: first oxide film
    3: BST layer 4: Second oxide film
    5: Photo register
    In the BST etching method according to the present invention, an oxide film is formed on a BST layer and patterned to expose a BST layer in a predetermined region. Then, an Ar / Cl 2 / SF 6 gas system is used as an etchant, and a low pressure, high density ICP (Inductively Coupled Plasma ) Method is used to etch the exposed BST layer.
    Another feature of the present invention is that when the BST layer is etched, the ICP power is 600 to 1400 W and the pressure is 0.1 to 100 mTorr.
    BST etching method according to the present invention having the above-described characteristics will now be described with reference to the accompanying drawings.
    1A to 1D are views showing a BST etching process according to the present invention. As shown in FIG. 1A, a first oxide film 2 is formed on a silicon substrate 1 by a thermal oxidation process to a thickness of about 5000 Å And a BST (Ba 1-X Sr x TiO 3 ) layer 3 is formed to a thickness of about 1000 Å on the first oxide film 2 by a sputtering method. Then, the second oxide film 4 is formed on the BST layer 3 to a thickness of about 6000 ANGSTROM by low-temperature chemical vapor deposition (LPCVD).
    Next, as shown in FIG. 1B, a photoresist 5 is formed on the second oxide film 4 and is patterned to expose a predetermined region of the second oxide film. Thereafter, a reactive ion etching process (RIE) The oxide film 4 is removed to expose the BST layer 3 in a certain region.
    At this time, when the second oxide film 4 is removed, CHF 3 / O 2 is used as an etchant.
    As shown in FIG. 1C, the remaining photoresist 5 is removed and the Ar / Cl 2 / SF 6 gas system is used as an etchant with the second oxide film 4 as a mask, The exposed BST layer 3 is etched using ICP9 Inductively Coupled Plasma method.
    At this time, when the BST layer (3) is etched, the ICP power is 600 to 1400 W and the pressure is 0.1 to 100 mTorr.
    Then, as shown in FIG. 1D, the remaining second oxide film 4 is removed to complete the BST etching process.
    Thus, in the etching of BST, the state of the plasma, the process pressure, and the etchant are factors affecting the etching rate improvement of BST, ensuring the selectivity ratio to the mask, and removal of residues and byproducts after etching.
    FIG. 2 is a schematic view of an apparatus for generating an ICP (Inductively Coupled Plasma) source. This ICP applies an RF electromagnetic field to an existing RIE (Reactive Ion Etcher) chamber through an inducting coil to form a high- And the ion kinetic energy in a horizontal direction on the substrate is set as an independent variable.
    ICP power, which is a characteristic element of ICP, affects etching rate and selectivity in BST etching.
    FIG. 3 is a graph showing the etching rate of BST and the selectivity of oxide film and BST according to ICP power, and FIG. 4 is a graph showing the etching rate of BST and selectivity of oxide film and BST according to the pressure.
    As shown in FIG. 3, as the ICP power is increased, the eutectic rate of the BST is increased and the selection ratio of the oxide film and BST used as the mask is hardly changed. These properties show that ICP power can be used as a parameter to improve the BST etch rate.
    In addition, BST is an oxide containing Ba, Sr, and Ti as constituent elements and can not produce easily volatile (ie, vaporizable) products (residues or byproducts) by the conventional etching method during BST etching Not only did this product have to be removed separately, but etching of the BST was very difficult due to redeposition of the etch residue by sputtering at process pressures above 100 mTorr.
    In order to etch the BST, the process can be performed at a pressure of 100 mTorr or less.
    That is, the products in the chamber can be easily removed in proportion to the lowering of the pressure.
    As shown in FIG. 4, as the pressure is lowered in the range of about 0.1 to 100 mTorr, the etching rate of the BST and the selectivity of the oxide film and the BST used as the mask are improved.
    FIG. 5A is a photograph showing the BST after etching according to the conventional method, and FIG. 5B is a photograph showing the BST after etching according to the method of the present invention.
    As shown in FIG. 5A, the prior art method forms by-products of the Cl system after BST etching.
    The reason for such by-products is that by-products are not volatile in the process conditions (pressure, temperature, RIE power, ICP power) of ICP.
    Therefore, in the present invention, as shown in FIG. 5B, by-products can be removed by adding SF 6 gas to the etchant of Ar / Cl 2 .
    In conclusion, the present invention is based on the fact that the BST is rapidly etched by forming an Ar / Cl 2 / SF 6 gas system into ICP (Inductively Coupled Plasma), and the second oxide film used as a mask is etched relatively slowly compared to BST, Which is a dry etching method capable of removing residues and by-products.
    The BST etching method according to the present invention has the following effects.
    First, by using the Ar / Cl 2 / SF 6 gas system as an etchant and using the low pressure and high density ICP method, the etching ratio of BST and the selectivity to the mask are improved.
    Second, after BST etching, residues and byproducts are removed, so that the process is simple and the contamination problem of the chamber can be solved.
    权利要求:
    Claims (6)
    [1" claim-type="Currently amended] Forming a BST layer on the substrate and forming a mask material on the BST layer;
    Exposing a BST layer in a predetermined region by patterning the mask material;
    Etching the exposed BST layer using an Ar / Cl 2 / SF 6 gas system as an etchant and an ICP (Inductively Coupled Plasma) method; And
    And removing the remaining mask material. ≪ RTI ID = 0.0 > 8. < / RTI >
    [2" claim-type="Currently amended] According to claim 1, BST etching method which is characterized in that the mask material is SiO 2.
    [3" claim-type="Currently amended] The BST etching method according to claim 1, wherein an ICP power is 600 to 1400 W and a pressure is 0.1 to 100 mTorr when the BST layer is etched.
    [4" claim-type="Currently amended] Sequentially forming a first oxide layer, a BST layer, and a second oxide layer on a substrate;
    Forming a photoresist on the second oxide film and patterning the exposed photoresist to expose a predetermined region of the second oxide film;
    Etching the exposed second oxide layer using the patterned photoresist as a mask to expose a BST layer in a predetermined region, and then removing the remaining photoresist;
    Etching the exposed BST layer using an Ar / Cl 2 / SF 6 gas system as an etchant and a low pressure, high density ICP (Inductively Coupled Plasma) method; And
    And removing the remaining second oxide film.
    [5" claim-type="Currently amended] The BST etching method according to claim 4, wherein, in etching the second oxide film, CHF 3 / O 2 is used as etchant.
    [6" claim-type="Currently amended] 5. The BST etching method according to claim 4, wherein, in etching the BST layer, the ICP power is 600 to 1400 W and the pressure is 0.1 to 100 mTorr.
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    同族专利:
    公开号 | 公开日
    KR100232158B1|1999-12-01|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1996-12-27|Application filed by 구자홍, 엘지전자 주식회사
    1996-12-27|Priority to KR1019960073512A
    1998-09-25|Publication of KR19980054364A
    1999-12-01|Application granted
    1999-12-01|Publication of KR100232158B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR1019960073512A|KR100232158B1|1996-12-27|1996-12-27|Bst etching method|
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