JP2018084783A - Film deposition material for resist process, patterning method and polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition material for resist process that can form a silicon-containing film that gives a resist pattern of good shape and prevents the collapse of it well, can be removed well by fluorine-based gas etching, and has good resistance to oxygen etching; a patterning method using the same; and a polymer suitable as the film deposition material for resist process.SOLUTION: A film deposition material for resist process contains a polymer having a structure represented by formula (1) and an organic solvent. In formula (1), Ris a C1-6 monovalent organic group having an oxygen atom; and in R, the ratio of the number of oxygen atoms to the number of carbon atoms is 0.35 or more. Ris C6-20 monovalent organic group having an aromatic ring.SELECTED DRAWING: None

Description

  The present invention relates to a film forming material for a resist process, a pattern forming method, and a polymer.

  For pattern formation of semiconductor elements, etc., a resist film is exposed and developed on a substrate to be processed via an organic antireflection film and a silicon-containing film, and etching is performed using the obtained resist pattern as a mask. The process is heavily used. In recent years, with the miniaturization of resist patterns, resist pattern collapse, rectangularity degradation, and the like have become problems, and therefore, resist pattern collapse suppression and good shape retention are required. Here, studies have been made on a silicon-containing film material for improving the shape of a resist pattern and a method for forming a pattern on a substrate using such a silicon-containing film material (Japanese Patent Laid-Open No. 2004-310019). No., International Publication No. 2012/039337).

JP 2004-310019 A International Publication No. 2012/039337

  However, when the resist pattern is miniaturized to a line width of 40 nm or less, the above conventional silicon-containing film cannot satisfy these requirements. In addition, as the resist pattern is miniaturized, it is necessary to reduce the thickness of the silicon-containing film, and thus it is necessary to further improve the oxygen etching resistance. Furthermore, there is a problem that the substrate to be processed is damaged when the silicon-containing film is removed by plasma etching or the like after the silicon-containing film pattern is formed using the resist pattern as a mask. Improvement of the system gas etching removability is also required.

  The present invention has been made based on the circumstances as described above, and its purpose is to form a silicon-containing film that is excellent in resist pattern shape and collapse inhibition, fluorine-based gas etching removability and oxygen etching resistance. It is to provide a polymer suitable as a component of a film forming material for a resist process, a pattern forming method using the same, and a component of such a film forming material for a resist process.

式（１）中、
Ｒ^１は、酸素原子を含む炭素原子数１〜６の１価の有機基（但し、ヒドロカルビルオキシ基を除く。）であり、Ｒ^１における酸素原子数の炭素原子数に対する比（以下「Ｏ／Ｃ比」ともいう。）は０．３５以上である。ここで、「有機基」とは、少なくとも１個の炭素原子を含む基をいう。
Ｒ^２は、炭素原子数１〜２０の１価の有機基、水素原子又はヒドロキシ基である。ａは、０、１又は２である。ａが２の場合、複数のＲ^２は、同一でも異なっていてもよい。ａが２の場合、複数のＲ^２は、互いに合わせられ、これらが結合するケイ素原子と共に環員数３〜２０の環構造を形成していてもよい。
Ｒ^３は、芳香環を含む炭素原子数６〜２０の１価の有機基（但し、上記Ｒ^１に該当するものを除く。）である。
Ｒ^４は、炭素原子数１〜２０の１価の有機基（但し、上記Ｒ^１に該当するものを除く。）、水素原子又はヒドロキシ基である。ｂは、０、１又は２である。ｂが２の場合、複数のＲ^４は、同一でも異なっていてもよい。ｂが２の場合、複数のＲ^４は、互いに合わせられ、これらが結合するケイ素原子と共に環員数３〜２０の環構造を形成していてもよい。
Ｒ^５は、炭素原子数１〜２０の１価の有機基（但し、上記Ｒ^１該当するもの及びＲ^３に該当するものを除く。）、水素原子又はヒドロキシ基である。ｃは、０〜３の整数である。ｃが２以上の場合、複数のＲ^５は、同一でも異なっていてもよい。ｃが２以上の場合、複数のＲ^５は、互いに合わせられ、これらが結合するケイ素原子と共に環員数３〜２０の環構造を形成していてもよい。
ｄは、上記重合体を構成する全構造単位に対する構造単位Ｕ_ｘのモル比率を表す。
ｅは、上記重合体を構成する全構造単位に対する構造単位Ｕ_Ｙのモル比率を表す。
ｆは、上記重合体を構成する全構造単位に対する構造単位Ｕ_Ｚのモル比率を表す。
ｄ、ｅ及びｆは、それぞれ０＜ｄ≦０．５５、０≦ｅ＜０．５５及び０．４５≦ｆ＜１を満たし、かつｄ＋ｅ＋ｆ≦１である。構造単位Ｕｘ、構造単位Ｕ_Ｙ及び構造単位Ｕ_Ｚはそれぞれ異なる。） This invention made | formed in order to solve the said subject is the film formation material for resist processes containing the polymer which has a structure represented by following formula (1), and an organic solvent.

In formula (1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms including an oxygen atom (excluding a hydrocarbyloxy group), and the ratio of the number of oxygen atoms in R ^{1 to} the number of carbon atoms (hereinafter referred to as “O / C ratio ") is 0.35 or more. Here, the “organic group” refers to a group containing at least one carbon atom.
R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, or a hydroxy group. a is 0, 1 or 2. When a is 2, the plurality of R ² may be the same or different. When a is 2, a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (except for those corresponding to R ¹ above).
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to the above R ¹ ), a hydrogen atom or a hydroxy group. b is 0, 1 or 2; When b is 2, the plurality of R ⁴ may be the same or different. If b is 2, a plurality of R ⁴ may be combined together, may form a ring structure ring members 3 to 20 together with the silicon atom to which they are attached.
R ⁵ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to R ¹ and those corresponding to R ³ ), a hydrogen atom or a hydroxy group. c is an integer of 0-3. When c is 2 or more, the plurality of R ⁵ may be the same or different. When c is 2 or more, a plurality of R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
d represents the molar ratio of the structural unit U _x to all structural units constituting the polymer.
e represents a molar ratio of structural units U _Y to the total structural units constituting the polymer.
f represents the molar ratio of structural units U _Z to the total structural units constituting the polymer.
d, e, and f satisfy 0 <d ≦ 0.55, 0 ≦ e <0.55, and 0.45 ≦ f <1, respectively, and d + e + f ≦ 1. Structural units Ux, the structural unit _{U Y} and structural units _{U Z} different. )

  Another invention made in order to solve the above-described problems includes a step of forming a silicon-containing film on at least one surface side of a substrate by using the film forming material for a resist process, a polymer having an acid dissociable group, and A step of forming a resist film on the surface of the silicon-containing film opposite to the substrate, a step of exposing the resist film, and a step of exposing the radiation-containing resin composition containing a radiation-sensitive acid generator. And a step of developing the resist film formed. The “acid-dissociable group” means a group that can be dissociated by the action of an acid generated from an acid generator or the like.

（式（１）中、
Ｒ^１は、酸素原子を含む炭素原子数１〜６の１価の有機基（但し、ヒドロカルビルオキシ基を除く。）であり、Ｒ^１におけるＯ／Ｃ比は０．３５以上である。
Ｒ^２は、炭素原子数１〜２０の１価の有機基、水素原子又はヒドロキシ基である。ａは、０、１又は２である。ａが２の場合、複数のＲ^２は、同一でも異なっていてもよい。ａが２の場合、複数のＲ^２は、互いに合わせられ、これらが結合するケイ素原子と共に環員数３〜２０の環構造を形成していてもよい。
Ｒ^３は、芳香環を含む炭素原子数６〜２０の１価の有機基（但し、上記Ｒ^１に該当するものを除く。）である。
Ｒ^４は、炭素原子数１〜２０の１価の有機基（但し、上記Ｒ^１に該当するものを除く。）、水素原子又はヒドロキシ基である。ｂは、０、１又は２である。ｂが２の場合、複数のＲ^４は、同一でも異なっていてもよい。ｂが２の場合、複数のＲ^４は、互いに合わせられ、これらが結合するケイ素原子と共に環員数３〜２０の環構造を形成していてもよい。
Ｒ^５は、炭素原子数１〜２０の１価の有機基（但し、上記Ｒ^１に該当するもの及びＲ^３に該当するものを除く。）、水素原子又はヒドロキシ基である。ｃは、０〜３の整数である。ｃが２以上の場合、複数のＲ^５は、同一でも異なっていてもよい。ｃが２以上の場合、複数のＲ^５は、互いに合わせられ、これらが結合するケイ素原子と共に環員数３〜２０の環構造を形成していてもよい。
ｄは、上記重合体を構成する全構造単位に対する構造単位Ｕ_ｘのモル比率を表す。
ｅは、上記重合体を構成する全構造単位に対する構造単位Ｕ_Ｙのモル比率を表す。
ｆは、上記重合体を構成する全構造単位に対する構造単位Ｕ_Ｚのモル比率を表す。
ｄ、ｅ及びｆは、それぞれ０＜ｄ≦０．５５、０≦ｅ＜０．５５及び０．４５≦ｆ＜１を満たし、かつｄ＋ｅ＋ｆ≦１である。構造単位Ｕｘ、構造単位Ｕ_Ｙ及び構造単位Ｕ_Ｚはそれぞれ異なる。） Yet another invention made to solve the above problems is a polymer having a structure represented by the following formula (1).

(In the formula (1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms containing an oxygen atom (excluding a hydrocarbyloxy group), and the O / C ratio in R ¹ is 0.35 or more.
R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, or a hydroxy group. a is 0, 1 or 2. When a is 2, the plurality of R ² may be the same or different. When a is 2, a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (except for those corresponding to R ¹ above).
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to the above R ¹ ), a hydrogen atom or a hydroxy group. b is 0, 1 or 2; When b is 2, the plurality of R ⁴ may be the same or different. If b is 2, a plurality of R ⁴ may be combined together, may form a ring structure ring members 3 to 20 together with the silicon atom to which they are attached.
R ⁵ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to R ¹ and those corresponding to R ³ ), a hydrogen atom or a hydroxy group. c is an integer of 0-3. When c is 2 or more, the plurality of R ⁵ may be the same or different. When c is 2 or more, a plurality of R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
d represents the molar ratio of the structural unit U _x to all structural units constituting the polymer.
e represents a molar ratio of structural units U _Y to the total structural units constituting the polymer.
f represents the molar ratio of structural units U _Z to the total structural units constituting the polymer.
d, e, and f satisfy 0 <d ≦ 0.55, 0 ≦ e <0.55, and 0.45 ≦ f <1, respectively, and d + e + f ≦ 1. Structural units Ux, the structural unit _{U Y} and structural units _{U Z} different. )

  According to the film forming material for a resist process of the present invention, it is possible to form a silicon-containing film excellent in resist pattern shape and collapse suppression, fluorine-based gas etching removability and oxygen etching resistance. Furthermore, a silicon-containing film having excellent solvent resistance can be formed. According to the pattern forming method of the present invention, it is possible to form a resist pattern that has a good shape and excellent collapse resistance. The polymer of the present invention can be suitably used as a component of the resist process film-forming material. Therefore, these can be suitably used for manufacturing semiconductor devices and the like that are expected to be further miniaturized in the future.

  Hereinafter, embodiments of the film forming material for resist process, the pattern forming method, and the polymer of the present invention will be described.

<Film forming material for resist process>
The resist process film-forming material of the present invention (hereinafter also simply referred to as “film-forming material”) contains [A] a polymer and [B] an organic solvent. The film-forming material may contain optional components such as [C] water, [D] nitrogen-containing compounds, and [E] acid generators as long as the effects of the present invention are not impaired. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] The polymer is a polymer having a structure represented by the following formula (1).

In the above formula (1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms containing an oxygen atom (excluding a hydrocarbyloxy group), and the O / C ratio in R ¹ is 0.35 or more.
R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, or a hydroxy group. a is 0, 1 or 2. When a is 2, the plurality of R ² may be the same or different. When a is 2, a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (except for those corresponding to R ¹ above).
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to the above R ¹ ), a hydrogen atom or a hydroxy group. b is 0, 1 or 2; When b is 2, the plurality of R ⁴ may be the same or different. If b is 2, a plurality of R ⁴ may be combined together, may form a ring structure ring members 3 to 20 together with the silicon atom to which they are attached.
R ⁵ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to R ¹ and those corresponding to R ³ ), a hydrogen atom or a hydroxy group. c is an integer of 0-3. When c is 2 or more, the plurality of R ⁵ may be the same or different. When c is 2 or more, a plurality of R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the [A] polymer.
e represents a molar ratio of structural units U _Y to the total structural units constituting the [A] polymers.
f represents the molar ratio of structural units U _Z to the total structural units constituting the [A] polymers.
d, e, and f satisfy 0 <d ≦ 0.55, 0 ≦ e <0.55, and 0.45 ≦ f <1, respectively, and d + e + f ≦ 1. Structural units Ux, the structural unit _{U Y} and structural units _{U Z} different.

  In addition, the molar ratio of each structural unit in the [A] polymer can be considered to be the same as the ratio of the charged amount of each corresponding silane monomer when the [A] polymer is synthesized by hydrolysis condensation of the silane monomer. .

  [A] When a resist pattern is formed on a resist film formed on the silicon-containing film after forming the silicon-containing film with the film-forming material containing the polymer, the shape of the resist pattern becomes better. In addition, the resist pattern collapse suppression property is further improved, and the fluorine-containing gas etching removability and oxygen etching resistance of the silicon-containing film are further improved.

[Structural unit U _x ]
The structural unit U _x is a structural unit represented by the following formula (U-1). [A] When the polymer has the structural unit U _x , fluorine gas etching removability of the silicon-containing film is improved, the shape of the resist pattern is improved, and collapse resistance of the resist pattern is also improved. It is guessed.

上記式（Ｕ−１）中、
Ｒ^１は、酸素原子を含む炭素原子数１〜６の１価の有機基（但し、ヒドロカルビルオキシ基を除く。）であり、Ｒ^１におけるＯ／Ｃ比は０．３５以上である。
Ｒ^２は、炭素原子数１〜２０の１価の有機基、水素原子又はヒドロキシ基である。ａは、０、１又は２である。ａが２の場合、複数のＲ^２は、同一でも異なっていてもよい。ａが２の場合、複数のＲ^２は、互いに合わせられ、これらが結合するケイ素原子と共に環員数３〜２０の環構造を形成していてもよい。
ｄは、［Ａ］重合体を構成する全構造単位に対する構造単位Ｕ_ｘのモル比率を表す。

In the above formula (U-1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms containing an oxygen atom (excluding a hydrocarbyloxy group), and the O / C ratio in R ¹ is 0.35 or more.
R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, or a hydroxy group. a is 0, 1 or 2. When a is 2, the plurality of R ² may be the same or different. When a is 2, a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the [A] polymer.

Examples of the monovalent organic group having 1 to 6 carbon atoms including the oxygen atom represented by R ¹ in the above formula (U-1) include, for example, carbon of a monovalent hydrocarbon group having 1 to 6 carbon atoms. A group having one or a plurality of linking groups containing an oxygen atom between carbons, a group obtained by substituting one or more hydrogen atoms of a monovalent hydrocarbon group having 1 to 6 carbon atoms with a monovalent substituent containing an oxygen atom Etc. Some or all of the hydrogen atoms of these hydrocarbon groups may be substituted with any substituent, and between the carbon-carbon of these hydrocarbon groups, a sulfide group (—S—) or the like A linking group containing no oxygen atom may be contained.

Here, the “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a cyclic structure and does not include an aromatic ring structure. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a cyclic structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure. In the present invention, the hydrocarbon group in R ¹ is preferably a chain hydrocarbon group or an alicyclic hydrocarbon group.

Examples of the linking group containing an oxygen atom include an ether group (—O—), a carbonyl group (—CO—), an ester group (—COO— or —OCO—), a sulfoxide group (—SO—), a sulfonyl group ( -SO ₂ -), a carbonate group (-OCOO -), - OC ( = O) C (= O) - , and the like. Examples of the monovalent substituent containing an oxygen atom include a hydroxyl group, a carboxy group, a formyl group, a nitro group, a nitroso group, a sulfo group, and —OC (═O) H.

Examples of the substituent which does not contain an oxygen atom among the above optional substituents in R ¹ include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, amino group, sulfanyl group (—SH) and the like. It is done.

The number of carbon atoms of the monovalent organic group represented by R ¹ is preferably 1 to 5, more preferably 1 to 4, more preferably 1 to 3, in order to improve oxygen etching resistance and fluorine gas etching removability. 1 and 2 are particularly preferred.

The number of oxygen atoms of the monovalent organic group represented by R ¹ is preferably 1 to 5, more preferably 1 to 4, more preferably 1 to 3, in order to improve oxygen etching resistance and fluorine gas etching removability. preferable.

The lower limit of the O / C ratio in the monovalent organic group represented by R ¹ is preferably 0.40, more preferably 0.45, and particularly preferably 0.60. On the other hand, the upper limit is preferably 3, more preferably 2, and particularly preferably 1.5.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ² include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent fat having 3 to 20 carbon atoms. Examples thereof include a cyclic hydrocarbon group and a hydrocarbyloxy group having 1 to 20 carbon atoms.

  Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, and 1-methylpropyl group. , T-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group and the like.

  Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a cyclopentyl group and a cyclohexyl group.

  Examples of the hydrocarbyloxy group having 1 to 20 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, a 2-methylpropoxy group, a 1-methylpropoxy group, and a t-butoxy group. N-hexyloxy group, n-heptyloxy group, n-octyloxy group and the like.

  As a in the said Formula (1), 0 and 1 are preferable and 0 is more preferable. By setting the a to 0, the silicon content of the [A] polymer increases, and oxygen etching resistance and the like can be further improved.

The structural unit U _X is obtained, for example, by hydrolysis condensation of silane monomer (I) having R ¹ of the above formula (1) and a hydrolyzable group bonded to a silicon atom. Examples of the hydrolyzable group include alkoxy groups such as methoxy group and ethoxy group, acyloxy groups such as acetoxy group, and halogen atoms such as chlorine atom.

  Specific examples of the silane monomer (I) include compounds represented by the following formulas (i-1) to (i-13). The silane monomer (I) may be used alone or in combination of two or more.

[A] The lower limit of the molar ratio d of the structural unit _{U X} to the total structural units constituting the polymer, preferably from 0.001, more preferably 0.01, more preferably 0.05, especially 0.1 preferable. On the other hand, the upper limit is preferably 0.5, more preferably 0.45, and still more preferably 0.4. By making the molar ratio d of the structural unit U _X equal to or more than the above lower limit, the fluorine gas etching removability can be further improved. On the other hand, the molar ratio d of the structural unit U _X is set to be lower than or equal the upper limit, it is possible to sufficiently contain other structural units, collapse inhibitory, it can be exhibited well balanced oxygen etching resistance and the like.

[Structural unit U _Z ]
The structural unit _UZ is a structural unit represented by the following formula (U-3). [A] When the polymer has the structural unit Uz, the solvent resistance and oxygen etching resistance of the silicon-containing film formed from the film forming material can be further improved.

In the above formula (U-3),
R ⁵ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to the above R ¹ and R ³ ), a hydrogen atom or a hydroxy group. c is an integer of 0-3. When c is 2 or more, the plurality of R ⁵ may be the same or different. When c is 2 or more, a plurality of R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
f represents the molar ratio of structural units U _Z to the total structural units constituting the [A] polymers.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ⁵ include R ¹ and R ³ from the monovalent organic group having 1 to 20 carbon atoms exemplified by R ² above. The thing remove | excluding group is mentioned.

R ⁵ is preferably a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, more preferably a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and further an ethyl group and a methyl group. A methyl group is preferable, and a methyl group is particularly preferable.

  As c in the formula (U-3), 0 and 1 are preferable, and 0 is more preferable. By setting c to 0, the silicon content of the [A] polymer increases, and the solvent resistance, oxygen etching resistance, and the like of the silicon-containing film formed from the film-forming material can be further improved.

[A] The lower limit of the molar ratio f of the structural unit _{U Z} to the total structural units constituting the polymer, preferably from 0.5, more preferably 0.55, more preferably 0.6, especially 0.65 preferable. On the other hand, the upper limit is preferably 0.95, more preferably 0.9, still more preferably 0.85, and particularly preferably 0.8. The molar ratio f of the structural unit U _Z With less lower than the lower limit and the upper limit, while more increasing the fluorine-based gas etching removal of the silicon-containing film formed by the film forming material, solvent resistance, oxygen etching resistance Etc. can be further improved.

[Structural unit U _Y ]
The structural unit _UY is a structural unit represented by the following formula (U-2). By [A] polymer having the structural unit U _Y, at the time of exposure for forming the resist pattern, it is possible to enhance the antireflection property of the silicon-containing film, such as interference due to reflected light during exposure is suppressed Since the shape of the resist pattern becomes better, the [A] polymer preferably contains the structural unit Uy.

In the above formula (U-2),
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (except for those corresponding to R ¹ above).
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to the above R ¹ ), a hydrogen atom or a hydroxy group. b is 0, 1 or 2; When b is 2, the plurality of R ⁴ may be the same or different. If b is 2, a plurality of R ⁴ may be combined together, may form a ring structure ring members 3 to 20 together with the silicon atom to which they are attached.
e represents a molar ratio of structural units U _Y to the total structural units constituting the [A] polymers.

Examples of the monovalent organic group having 6 to 20 carbon atoms including the aromatic ring represented by R ³ include aromatics having 6 to 20 carbon atoms such as aryl groups and aralkyl groups having 6 to 20 carbon atoms. A hydrocarbon group is mentioned. This aromatic hydrocarbon group may have a substituent.

  Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthracenyl group.

  Examples of the aralkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group.

Examples of the substituent which may be possessed by the aromatic hydrocarbon group, for example, such as those similar to the substituents exemplified for R ¹ above can be mentioned.

R ³ is preferably an aryl group having 6 to 20 carbon atoms, more preferably a phenyl group, a methylphenyl group, or a fluorophenyl group.

As the monovalent organic group having 1 to 20 carbon atoms represented by R ⁴ , for example, a group corresponding to R ¹ is excluded from the monovalent organic group having 1 to 20 carbon atoms exemplified by R ² above. And the like.

  As b in the formula (U-2), 0 and 1 are preferable, and 0 is more preferable. By setting b to 0, the silicon content of the [A] polymer increases, and oxygen etching resistance and the like can be further improved.

[A] The lower limit of the molar ratio e of the structural unit U _Y to the total structural units constituting the polymer is preferably 0.01, more preferably 0.05, still more preferably 0.08, and particularly preferably 0.1. preferable. On the other hand, the upper limit is preferably 0.4, more preferably 0.3, still more preferably 0.25, and particularly preferably 0.2. The molar ratio e of the structural unit U _Y is set to lower than or equal to the lower limit and not more than the upper limit, it is possible to better balanced manner exhibited anti-reflection property, the resist pattern shape and the collapse inhibitory like.

[Other structural units]
[A] The polymer may have other structural units other than the structural units U _X , U _Y and U _Z. Examples of other structural units include structural units derived from silane monomers containing a plurality of silicon atoms, such as hexamethoxydisilane, bis (trimethoxysilyl) methane, polydimethoxymethylcarbosilane, and the like. [A] When the polymer has other structural units, the upper limit of the molar ratio of the other structural units to the total structural units constituting the [A] polymer is preferably 0.2, more preferably 0.1. 0.03 is more preferable, and 0.01 is particularly preferable.

  [A] The lower limit of the content of the polymer is preferably 50% by mass, more preferably 70% by mass, still more preferably 80% by mass, and particularly preferably 90% by mass with respect to the total solid content of the film-forming material. preferable. [A] By setting the content of the polymer to the above lower limit or more, the resist pattern shape and collapse suppression property, fluorine gas etching removability and oxygen etching resistance of the silicon-containing film can be sufficiently improved. The total solid content of the film forming material refers to the sum of components other than [B] organic solvent and [C] water. [A] Only one type of polymer may be contained, or two or more types may be contained.

  [A] The lower limit of the weight average molecular weight (Mw) of the polymer is preferably 1,000, more preferably 1,300, still more preferably 1,500, and particularly preferably 1,900. The upper limit of Mw is preferably 50,000, more preferably 10,000, even more preferably 5,000, and particularly preferably 3,000.

  Mw of [A] polymer in this specification uses the Tosoh GPC column ("G2000HXL", "G3000HXL" and "G4000HXL"), elution solvent: tetrahydrofuran, flow rate: 1. This is a value measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under analysis conditions of 0 mL / min and column temperature: 40 ° C.

  [A] The polymer can be obtained by a method of hydrolyzing and condensing a hydrolyzable silane monomer corresponding to each structural unit described above.

  [A] Of the solvents in the reaction solution during the synthesis of the polymer, the upper limit of the content of the alcohol solvent having a boiling point of 100 ° C. or lower is preferably 20% by mass, and more preferably 5% by mass. The alcohol solvent having a boiling point of 100 ° C. or less may be generated during the hydrolysis condensation of each of the above silane monomers, and the content of the solvent in the reaction solution is 20% by mass or less, preferably 5% by mass or less. It is preferable to remove the alcohol solvent having a boiling point of 100 ° C. or lower by distillation or the like.

<[B] Organic solvent>
[B] Any organic solvent can be used as long as it can dissolve or disperse the polymer and optional components.

  [B] Examples of the organic solvent include alcohol solvents, ketone solvents, ether solvents, ester solvents, and the like.

Examples of alcohol solvents include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol , Sec-octanol, n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, Monoalcohol solvents such as phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, phenylmethylcarbinol, diacetone alcohol, cresol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, Examples thereof include polyhydric alcohol solvents such as 2-methyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol and glycerin.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n- Examples include hexyl ketone, di-i-butyl ketone, trimethylnonanone, cyclohexanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone, and fencheon.

  Examples of ether solvents include diethyl ether, ethyl methyl ether, ethylene oxide, 1,2-propylene oxide, dioxolane, 4-methyldioxolane, dioxane, dimethyl dioxane, 2-methoxyethanol, 2-ethoxyethanol, ethylene glycol diethyl ether, 2-n-butoxyethanol, 2-n-hexoxyethanol, 2-phenoxyethanol, 2- (2-ethylbutoxy) ethanol, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol mono- n-butyl ether, diethylene glycol di-n-butyl ether, diethylene glycol mono-n- Xyl ether, ethoxy triglycol, tetraethylene glycol di-n-butyl ether, 1-n-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether , Dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran and the like.

  Examples of ester solvents include diethyl carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, N-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, aceto Ethyl acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, Propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxytriglycol acetate, Ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, phthalic acid Examples thereof include dimethyl and diethyl phthalate.

  [B] Among organic solvents, ether solvents and ester solvents are preferred, and ether solvents and ester solvents having a glycol structure are more preferred.

  Examples of ether solvents and ester solvents having a glycol structure include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl acetate Examples include ether.

  [B] Only one organic solvent may be used, or two or more organic solvents may be combined.

  As a minimum of content of [B] organic solvent in the film formation material, 90 mass% is preferred, 92 mass% is more preferred, and 96 mass% is still more preferred. As an upper limit of the said content, 99.5 mass% is preferable and 99.0 mass% is more preferable.

<[C] water>
The film-forming material may contain [C] water as necessary. When the film forming material further contains [C] water, the [A] polymer and the like are hydrated, so that the storage stability of the film forming material is improved. Further, by containing [C] water, curing during film formation is promoted, and a denser silicon-containing film can be obtained.

  When the film forming material contains [C] water, the lower limit of the content of [C] water in the film forming material is preferably 0.01% by mass, more preferably 0.1% by mass, and 3% by mass is more preferable. The upper limit of the content is preferably 10% by mass, more preferably 5% by mass, still more preferably 2% by mass, and particularly preferably 1% by mass.

<[D] Nitrogen-containing compound>
[D] The nitrogen-containing compound is a compound having a nitrogen atom. When the film-forming material contains a [D] nitrogen-containing compound, the resist pattern collapse resistance can be further improved. Moreover, the hardening at the time of film formation proceeds, and the strength of the obtained silicon-containing film can be further increased. [D] Only one nitrogen-containing compound may be used, or two or more nitrogen-containing compounds may be used in combination.

  [D] The nitrogen-containing compound is preferably a compound having a basic amino group and a compound that generates a basic amino group by the action of an acid or heat in order to promote the crosslinking reaction.

  Examples of the compound having a basic amino group and the compound that generates a basic amino group by the action of an acid or heat include amine compounds, amide group-containing compounds, nitrogen-containing heterocyclic compounds, and the like.

Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4 -Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1,4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ′, N′-pentamethyldiethylenetriamine and the like can be mentioned.

Examples of the amide group-containing compound include Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonyl-2-carboxy-4-hydroxypyrrolidine, Nt-butoxycarbonyl-2-carboxypyrrolidine and the like. A t-butoxycarbonyl group-containing amino compound;
Nt-amyloxycarbonyl group-containing amino compounds such as Nt-amyloxycarbonyl-4-hydroxypiperidine;
N- (9-anthrylmethyloxycarbonyl) group-containing amino compounds such as N- (9-anthrylmethyloxycarbonyl) piperidine;
Formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine and the like Can be mentioned.

  [D] Among nitrogen-containing compounds, amide group-containing compounds are preferred. As the amide group-containing compound, an Nt-butoxycarbonyl group-containing amino compound, an Nt-amyloxycarbonyl group-containing amino compound, and an N- (9-anthrylmethyloxycarbonyl) group-containing amino compound are preferable. t-butoxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonyl-2-carboxy-4-hydroxypyrrolidine, Nt-butoxycarbonyl-2-carboxy-pyrrolidine, Nt-amyloxycarbonyl-4-hydroxy Piperidine and N- (9-anthrylmethyloxycarbonyl) piperidine are more preferred.

  When the film-forming material contains a [D] nitrogen-containing compound, the lower limit of the content of the [D] nitrogen-containing compound is preferably 0.1 parts by mass with respect to 100 parts by mass of the [A] polymer. 1 part by mass is more preferred, and 3 parts by mass is still more preferred. As an upper limit of the said content, 30 mass parts is preferable, 15 mass parts is more preferable, and 10 mass parts is further more preferable. [D] By making the content of the nitrogen-containing compound not less than the above lower limit and not more than the above upper limit, the resist pattern collapse inhibitory property and the like can be further improved.

<[E] acid generator>
[E] The acid generator is a compound that generates an acid upon irradiation with radiation such as ultraviolet rays and / or heating. When the film forming material contains an [E] acid generator, curing at the time of film formation can be promoted, and as a result, the strength of the silicon-containing film can be further increased, and solvent resistance and oxygen gas etching can be achieved. Resistance can be increased. [E] Examples of the acid generator include onium salts such as sulfonium salts and iodonium salts, and sulfone compounds such as N-sulfonyloxyimide compounds.

Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2- (3-tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1 Difluoroethanesulfonate, triphenylsulfonium N, N′-bis (nonafluoro-n-butanesulfonyl) imidate, triphenylsulfonium salicylate, triphenylsulfonium camphorsulfonate, triphenylsulfonium Cyclo [3.3.1.1 ^{3, 7]} triphenylsulfonium salts such as decanyl difluoromethane sulfonate;
4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2. 2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexyl-phenyl diphenyl sulfonium 2- (3-tetracyclo ^[4.4.0.1 2,5 ^{.1 7, 10]} dodecanyl) -1,1-difluoroethanesulfonate, 4-cyclohexyl-phenyl diphenyl sulfonium N, N'-bis (nonafluoro -n- butanesulfonyl) imidate And 4-cyclohexyl-phenyl camphorsulfonate 4-cyclohexyl-phenyl diphenyl sulfonium salts;
4-t-butylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-t-butylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-t-butylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-t-butylphenyl Diphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-t-butylphenyldiphenylsulfonium 2- (3-tetracyclo [4.4. 0.1 ^2,5 .1 ^7,10] dodecanyl difluoroethane sulfonate, 4-t-butylphenyl diphenyl sulfonium N, N'-bis (nonafluoro -n- butanesulfonyl) imidate, 4-t-butyl Phenyldi 4-t-butylphenyl diphenyl sulfonium salts such as E sulfonyl sulfonium camphorsulfonate;
Tri (4-t-butylphenyl) sulfonium trifluoromethanesulfonate, tri (4-t-butylphenyl) sulfonium nonafluoro-n-butanesulfonate, tri (4-t-butylphenyl) sulfonium perfluoro-n-octanesulfonate, Tri (4-t-butylphenyl) sulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, tri (4-t-butylphenyl) sulfonium 2 - (3-tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl difluoroethane sulfonate, tri (4-t- butylphenyl) sulfonium N, N'-bis (nonafluoro - n-butanesulfonyl) imidate, tri (4-t-butylphenyl) sulfo And tri (4-t- butylphenyl) sulfonium salts such as Um camphor sulfonates.

Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethane sulfonate, diphenyliodonium 2- (3-tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoroethanesulfonate, diphenyliodonium Diphenyliodonium salts such as N, N′-bis (nonafluoro-n-butanesulfonyl) imidate, diphenyliodonium camphorsulfonate;
Bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, Bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium 2 - (3-tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoroethanesulfonate, bis (4-t- butylphenyl) iodonium N, N'-bis (nonafluoro -N-butanesulfonyl) imidate, bis (4-t-butylphenyl) io Bis (4-t- butylphenyl) iodonium salts such as iodonium camphorsulfonate and the like.

Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) succinimide, N- (nonafluoro-n-butanesulfonyloxy) succinimide, N- (perfluoro-n-octanesulfonyloxy) succinimide, N- ( 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) succinimide, N- (2- (3-tetracyclo [4.4.0.1 ^{2] ,} 5.1 ^7,10 ] dodecanyl) -1,1-difluoroethanesulfonyloxy) succinimide, N- (camphorsulfonyloxy) succinimide and the like;
N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [2.2.1] hept -5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- ( 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboxy imide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoroethane-sulfonyloxy) bicyclo [2.2.1] hept Bicyclo [2.2.1] such as -5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide. And hept-5-ene-2,3-dicarboximide compound.

  These [E] acid generators may be used alone or in combination of two or more.

  [E] The acid generator is preferably an onium salt, and more preferably a sulfonium salt.

  When the film forming material contains an [E] acid generator, the lower limit of the content of the [E] acid generator with respect to 100 parts by mass of the [A] polymer is preferably 0.01 parts by mass. 1 mass part is more preferable, 0.5 mass part is further more preferable, and 1 mass part is especially preferable. As an upper limit of the said content, 20 mass parts is preferable, 10 mass parts is more preferable, and 5 mass parts is further more preferable. [E] By making content of an acid generator more than the said minimum and below the said upper limit, the collapse inhibitory property of a resist pattern, etc. can be improved further.

<Other optional components>
The film forming material may contain other optional components in addition to the components [A] to [E]. Examples of other optional components include surfactants, colloidal silica, colloidal alumina, and organic polymers. When the said film forming material contains another arbitrary component, as an upper limit of the content, 2 mass parts is preferable with respect to 100 mass parts of [A] polymers, and 1 mass part is more preferable.

<Method for preparing film forming material for resist process>
The method for preparing the film-forming material is not particularly limited. For example, [A] a polymer, [B] an organic solvent, and if necessary, [C] water, [D] a nitrogen-containing compound, [E] an acid generator, and the like. It can be prepared by mixing at a predetermined ratio, and preferably by filtering the obtained mixed solution with a filter having a pore size of about 0.2 μm.

  As a minimum of solid content concentration of the film formation material, 0.01 mass% is preferred, 0.1 mass% is more preferred, 0.5 mass% is still more preferred, and 1 mass% is especially preferred. The upper limit of the solid content concentration is preferably 20% by mass, more preferably 10% by mass, further preferably 4% by mass, and particularly preferably 3% by mass. The solid content concentration of the film forming material is calculated by measuring the mass (g) of the solid content in 0.5 g of the polymer solution by baking 0.5 g of the film forming material at 250 ° C. for 30 minutes. Value (mass%).

<Applications and silicon-containing films>
Since the silicon-containing film obtained from the film-forming material is etched at a high speed with a fluorine-based gas, when used as a resist intermediate film, a resist pattern having a good shape can be formed on this surface. Therefore, the film forming material can be suitably used as a resist intermediate film forming material in a resist process, particularly in a multilayer resist process. Among the multilayer resist processes, it can be particularly suitably used in pattern formation using a multilayer resist process in a region finer than 40 nm (ArF, ArF in immersion exposure, F ₂ , EUV, nanoimprint, etc.).

  The silicon-containing film is formed by applying the film-forming material described above to the surface of a substrate or another lower layer film such as an organic lower layer film, and heat-treating and curing the coating film. Can be formed.

  Examples of the method for applying the film forming material include spin coating, roll coating, and dip. As temperature of heat processing, it is 50 to 550 degreeC normally. The lower limit of the average thickness of the formed silicon-containing film is preferably 5 nm and more preferably 10 nm. The upper limit of the average thickness is preferably 200 nm, more preferably 50 nm, and even more preferably 30 nm.

  The film forming material can also be used for resist process applications other than the formation of a resist intermediate film in a resist process, such as a pattern forming material obtained through an inversion process (inversion pattern).

<Pattern formation method>
The pattern forming method includes a step of forming a silicon-containing film on at least one surface side of a substrate with the film-forming material (hereinafter also referred to as “silicon-containing film forming step”), and a heavy layer having an acid dissociable group. A step of forming a resist film on the surface of the silicon-containing film opposite to the substrate with a radiation-sensitive resin composition containing a coalescence and a radiation-sensitive acid generator (hereinafter also referred to as “resist film formation step”). ), A step of exposing the resist film (hereinafter also referred to as “exposure step”), and a step of developing the exposed resist film (hereinafter also referred to as “development step”). The pattern forming method includes, before the silicon-containing film forming step, a step of forming an organic underlayer film on the surface side of the substrate on which the silicon-containing film is formed (hereinafter also referred to as “organic underlayer film forming step”). It is also possible to provide a step of etching the silicon-containing film or the organic underlayer film (hereinafter also referred to as “etching step”) using the resist pattern as a mask after the development step. Hereinafter, each step will be described.

(Organic underlayer forming process)
In this step, an organic underlayer film is formed on the surface side of the substrate on which the silicon-containing film is formed.

  Examples of the substrate include an insulating film such as silicon oxide, silicon nitride, silicon oxynitride, and polysiloxane, a resin substrate, and the like. For example, an interlayer insulating film such as a wafer covered with a low dielectric insulating film formed by “Black Diamond” from AMAT, “Silk” from Dow Chemical, “LKD5109” from JSR, or the like can be used. As this substrate, a patterned substrate such as a wiring groove (trench) or a plug groove (via) may be used.

  The organic underlayer film is different from the silicon-containing film formed from the film forming material. The organic underlayer film has a predetermined function (for example, antireflection) required to further supplement the functions of the silicon-containing film and / or the resist film in forming a resist pattern, or to obtain a function that they do not have. Film, coating film flatness, and high etching resistance against fluorine-based gas).

  Examples of the organic underlayer film include an antireflection film. Examples of the composition for forming an antireflection film include “NFC HM8006” manufactured by JSR Corporation.

  The organic underlayer film can be formed by applying a composition for forming an organic underlayer film by a spin coating method or the like to form a coating film, and then heating.

(Silicon-containing film formation process)
In this step, a silicon-containing film is formed on at least one surface side of the substrate with the film forming material. When the organic underlayer film is formed on the substrate, it is formed on the surface opposite to the substrate of the organic underlayer film. Thereby, the substrate with a silicon-containing film in which the silicon-containing film is formed on the substrate can be obtained.

  The method for forming the silicon-containing film is not particularly limited. For example, the coating film formed by applying the film-forming material on the substrate by a known method such as a spin coating method is cured by exposure and / or heating. Can be formed.

  Examples of radiation used for exposure include visible light, ultraviolet light, far ultraviolet light, X-rays, electron beams, γ-rays, molecular beams, and ion beams. As a minimum of the temperature at the time of heating a coating film, 50 degreeC is preferable, 90 degreeC is more preferable, 150 degreeC is further more preferable, 200 degreeC is especially preferable. As an upper limit of the said temperature, 550 degreeC is preferable, 450 degreeC is more preferable, 400 degreeC is further more preferable, and 300 degreeC is especially preferable. As a minimum of average thickness of a silicon content film formed, 5 nm is preferred, 10 nm is more preferred, and 12 nm is still more preferred. The upper limit is preferably 200 nm, more preferably 100 nm, still more preferably 40 nm, and particularly preferably 30 nm.

(Resist film formation process)
In this step, a resist film is formed on the surface of the silicon-containing film opposite to the substrate.

  As the resist composition used for forming the resist film, a positive type containing a polymer having an acid dissociable group and a radiation sensitive resin composition containing a radiation sensitive acid generator, an alkali-soluble resin and a quinonediazide photosensitizer Although the negative resist composition containing a resist composition, alkali-soluble resin, and a crosslinking agent can be mentioned, the said radiation sensitive resin composition is preferable. When the radiation sensitive resin composition is used, a positive pattern can be formed by developing with an alkaline developer, and a negative pattern can be formed by developing with an organic solvent. For the formation of the resist pattern, a double patterning method, a double exposure method, or the like, which is a method for forming a fine pattern, may be used as appropriate.

  The solid content concentration of the resist composition is not particularly limited, but is preferably 5% by mass or more and 50% by mass or less. Moreover, as a resist composition, what was filtered using the filter with a hole diameter of about 0.2 micrometer can be used conveniently. In the pattern forming method of the present invention, a commercially available resist composition can be used as it is as such a resist composition.

  The method for applying the resist composition is not particularly limited, and can be applied by a conventional method such as a spin coating method. When applying the resist composition, the amount of the resist composition to be applied is adjusted so that the resulting resist film has a predetermined thickness.

  The resist film can be formed by volatilizing the solvent in the coating film by pre-baking the coating film formed by applying the resist composition. The pre-baking temperature is appropriately adjusted according to the type of resist composition to be used, and the like. The lower limit of the pre-baking temperature is preferably 30 ° C., more preferably 50 ° C. As an upper limit of the said temperature, 200 degreeC is preferable and 150 degreeC is more preferable.

(Exposure process)
In this step, the resist film is exposed. The exposure is performed by selectively irradiating with radiation through a photomask.

The radiation used for the exposure includes visible light, ultraviolet light, deep ultraviolet light, X-rays, electron beams, gamma rays, molecular beams, ion beams, etc., depending on the type of acid generator used in the resist composition. Among them, far ultraviolet rays are preferable, and KrF excimer laser light (248 nm), ArF excimer laser light (193 nm), F ₂ excimer laser light (wavelength 157 nm), Kr ₂ excimer laser light ( A wavelength of 147 nm), an ArKr excimer laser (light wavelength of 134 nm) and extreme ultraviolet light (wavelength of 13 nm, etc.) are more preferable. Further, the exposure method is not particularly limited, and can be performed in accordance with a conventionally known method for forming a resist pattern.

(Development process)
In this step, the exposed resist film is developed to form a resist pattern.

  The development may be alkali development or organic solvent development, but when the organic solvent development is used, the shape of the resist pattern becomes better, and the resist pattern collapse resistance can be further improved.

  Examples of the developer used for alkali development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, and methyl. Diethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [ 4.3.0] -5-nonene and the like. Further, these aqueous solutions may be those obtained by adding an appropriate amount of a water-soluble organic solvent, for example, alcohols such as methanol and ethanol, surfactants and the like.

  Examples of the organic solvent developer used for organic solvent development include ketone solvents, alcohol solvents, amide solvents, ether solvents, ester solvents, and the like. Examples of these solvents include those similar to the respective solvents exemplified as the [B] organic solvent. These solvents may be used alone or in combination as a mixture with water.

  When the resist film formed from the radiation-sensitive resin composition is developed with an organic solvent, the polarity of the exposed portion is increased, so that the exposed portion becomes a resist pattern. On the other hand, the exposed portion on the surface of the silicon-containing film formed from the film-forming material has increased hydrophilicity due to the acid generated by the acid generator. For this reason, the adhesiveness between the resist film and the silicon-containing film is high with respect to the organic solvent which is the developer, and the resist pattern collapse resistance and the like can be further improved.

  A predetermined resist pattern corresponding to the photomask can be formed by performing development with a developer and then washing and drying.

  In this step, post-baking is preferably performed before development in order to improve resolution, pattern profile, developability, and the like. The post-baking temperature is appropriately adjusted according to the type of resist composition used, but the lower limit of the post-baking temperature is preferably 50 ° C., more preferably 80 ° C. As an upper limit of the said temperature, 200 degreeC is preferable and 150 degreeC is more preferable.

(Etching process)
In this step, the silicon-containing film is dry-etched using the resist pattern as a mask to form a silicon-containing film pattern.

The dry etching can be performed using a known dry etching apparatus. Further, as a source gas at the time of dry etching, although depending on the elemental composition of the film to be etched, for example, fluorine gas such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ , Cl ₂ , Chlorine gas such as BCl ₃ , oxygen gas such as O ₂ and O ₃ , H ₂ , NH ₃ , CO, CO ₂ , CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ , C ₃ Reducing gas such as H ₄ , C ₃ H ₆ , C ₃ H ₈ , HF, HI, HBr, HCl, NO, NH ₃ , BCl ₃ , inert gas such as He, N ₂ , Ar, etc. are used, These gases can be mixed and used. For dry etching of a silicon-containing film, a fluorine-based gas is usually used, and a mixture of an oxygen-based gas and an inert gas is preferably used.

  When using a substrate on which an organic underlayer film is formed, the organic underlayer film is also dry etched to form a pattern of the organic underlayer film.

  According to the pattern forming method, a predetermined pattern can be formed by appropriately performing the above steps.

<Silicon-containing film removal process>
In this step, after the pattern is formed by the pattern forming method and the substrate to be processed is processed, the silicon-containing film is removed by dry etching. The dry etching can be performed using a known dry etching apparatus. Further, as a source gas at the time of dry etching, for example, fluorine-based gas such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ , chlorine-based gas such as Cl ₂ , BCl _3, or the like is used. These gases can be mixed and used.

<Polymer>
The polymer which concerns on one Embodiment of this invention is a polymer which has a structure represented by the said Formula (1). The details of the polymer are as described above for the [A] polymer that is a component of the “film forming material for resist process”, and the description thereof is omitted here. The said polymer can be used suitably as a component of the film forming material for resist processes.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The solid content concentration of the polymer solution and the weight average molecular weight (Mw) of the [A] polymer in this example were measured by the following methods.

[Solid content concentration of polymer solution]
The mass (g) of solid content in 0.5 g of the polymer solution was measured by baking 0.5 g of the polymer solution at 250 ° C. for 30 minutes, and the solid content concentration (% by mass) of the polymer solution was calculated.

[Weight average molecular weight (Mw)]
Using Tosoh's GPC columns ("G2000HXL", "G3000HXL" and "G4000HXL"), elution solvent: tetrahydrofuran, flow rate: 1.0 mL / min, column temperature: 40 ° C. Measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard.

<[A] Synthesis of polymer>
[A] Silane monomers used for polymer synthesis are shown below.
Compound (M-1) ~ (M -11): the following formula (M-1) ~ (M -11) compounds represented by compound (M-1) is a silane monomer giving the structural unit _{U Z,} compound (M-2) and (M-3) is a silane monomer giving the structural unit _{U Y,} compound (M-4) ~ (M -10) is a silane monomer giving the structural unit _{U X.} The compound (M-11) is not a silane monomers O / C ratio give structural units U _X for less than 0.35, a compound for comparison using the film-forming material of Comparative Example 2-2 is there.

[Example 1-1] (Synthesis of polymer A-1)
An aqueous oxalic acid solution was prepared by mixing 5.93 g of an aqueous 10% by mass oxalic acid dihydrate solution and 3.56 g of water. Then, 12.38 g (66 mol%) of the compound (M-1), 2.50 g (14 mol%) of the compound (M-2), 4.00 g (20 mol%) of the compound (M-4) and methanol 11. A cooling tube and a dropping funnel containing the oxalic acid aqueous solution prepared above were set in a flask containing 62 g. Subsequently, after heating this flask to 60 degreeC with an oil bath, the said oxalic acid aqueous solution was dripped slowly, and it was made to react at 60 degreeC for 4 hours. After completion of the reaction, the flask containing the reaction solution was allowed to cool and then replaced with propylene glycol monomethyl ether acetate, set in an evaporator, and methanol was removed to obtain 74 g of a resin solution. Let solid content in this resin solution be a polymer (A-1). The solid content in the obtained resin solution was 9.8% by mass. Moreover, Mw of the obtained polymer (A-1) was 2,450.

[Examples 1-2 to 1-8, Synthesis Examples 1-1 and 1-2] (Polymers (A-2) to (A-8) and Polymers (a-1) and (a-2)) Synthesis)
The polymers (A-2) to (A-8) and the polymer (a-1) were prepared in the same manner as in Example 1 except that the silane monomers having the types and amounts shown in Table 1 were used. And (a-2) were synthesized. The solid content concentration (mass%) of the obtained polymer solution and the Mw of the [A] polymer are shown together in Table 1. In addition, the numerical value shown in the parenthesis in the column of M-4 to M-11 in Table 1 is the O / C ratio of each of the compounds (M-4) to (M-11).

  In the following Table 1, the polymer (a-1) has a charged amount of the compound (M-1) giving the structural unit Uz of 40 mol%, and f in the above formula (1) is less than 0.45. This does not correspond to the example, and is referred to as “Synthesis Example 1-1”. In addition, since the polymer (a-2) has an O / C ratio of less than 0.35 in the compound (M-11) as described above, it does not fall under the examples and is referred to as “Synthesis Example 1-2”. .

[Preparation of film forming material for resist process]
Components other than the [A] polymer used for the preparation of the film forming material for resist process are shown below.

[[B] Organic solvent]
B-1: Propylene glycol monomethyl ether acetate

[[C] water]
C: Water

[Example 2-1]
[A] 1.5 parts by mass of (A-1) as a polymer (solid content), [B] 98.0 parts by mass of (B-1) as an organic solvent, and [C] 0.5 parts by mass of water And the obtained mixed solution was filtered through a filter having a pore size of 0.2 μm to obtain a film forming material (J-1) for resist process.

[Examples 2-2 to 2-8 and Comparative Examples 2-1 and 2-2]
Resist process film-forming materials (J-2) to (J-8) and (j) in the same manner as in Example 2-1, except that the components of the types and blending amounts shown in Table 2 below were used. -1) and (j-2) were prepared.

<Formation of silicon-containing film>
Each of the obtained film forming materials for a process is applied on a silicon wafer by a spin coater using a spin coater (“CLEAN TRACK ACT12” from Tokyo Electron), and then for 1 minute on a 220 ° C. hot plate. After the heat treatment, the silicon-containing film having an average thickness of 25 nm shown in Examples 3-1 to 3-8 and Comparative Examples 3-1 to 3-2 in Table 3 was formed by cooling at 23 ° C. for 60 seconds. A substrate was obtained. The average thickness of the silicon-containing film was measured with a film thickness measuring device (“M-2000D” manufactured by JA Woollam).

<Evaluation>
About the formed silicon-containing film | membrane, the following item was evaluated by the method shown below. The evaluation results are shown in Table 3 below.

[Substrate reflectivity]
Refractive index parameters (n) and extinction of the silicon-containing film, the underlayer film forming composition (“NFC HM8006” from JSR) and the radiation-sensitive resin composition (“ARF AR2772JN” from JSR) formed above. The attenuation coefficient (k) was measured with a high-speed spectroscopic ellipsometer (JA Woollam “M-2000”), and based on this measurement value, simulation software (KLA-TENCOR “Prolith”) was used. The substrate reflectance of the laminate of resist film / silicon-containing film / organic underlayer film under the conditions of NA 1.3 and Dipole was determined. The substrate reflectance was evaluated as “A” (good) when 1% or less, and “B” (defective) when it exceeded 1%.

[Solvent resistance]
The obtained substrate on which the silicon-containing film was formed was immersed in cyclohexane for 10 seconds at room temperature. The average thickness before and after immersion of the silicon-containing film was measured using a spectroscopic ellipsometer (“UV1280E” manufactured by KLA-TENCOR). When the average thickness before immersion was T ₀ and the average thickness after immersion was T ₁ , the film thickness change rate (%) due to solvent immersion was determined by the following formula.
Film thickness change rate (%) = | T ₁ −T ₀ | × 100 / T ₀
The solvent resistance was evaluated as “A” (good) when the rate of change in film thickness was less than 1%, and “B” (bad) when 1% or more.

[Resistence of resist pattern collapse and resist pattern shape]
The resist pattern collapse inhibition property and the resist pattern shape were evaluated by performing the following lithography evaluation.

(Lithography evaluation, organic solvent development)
An organic underlayer film forming material (“NFC HM8006” manufactured by JSR) was spin-coated on a 12-inch silicon wafer with a spin coater, and then heat-treated at 250 ° C. for 60 seconds to form an organic underlayer film having an average thickness of 100 nm. . On the organic underlayer film, the obtained film forming material for a resist process is spin-coated by the spin coater, heat-treated at 220 ° C. for 60 seconds, and then cooled at 23 ° C. for 60 seconds to obtain an average thickness of 25 nm. A silicon-containing film was formed. Next, a radiation-sensitive resin composition (“ARF AR2772JN” from JSR) is spin-coated on the silicon-containing film by the above spin coater, heat-treated at 90 ° C. for 60 seconds, and then cooled at 23 ° C. for 30 seconds. Thus, a resist film having an average thickness of 100 nm was formed.

  Next, using an ArF immersion exposure apparatus (“S610C” manufactured by NIKON), exposure was performed through a mask having a mask size for forming a 40 nm line / 80 nm pitch under the optical conditions of NA: 1.30 and Dipole. Post baking at 100 ° C. for 60 seconds on a “Lithius Pro-i” hot plate, cooling at 23 ° C. for 30 seconds, and then paddle development with butyl acetate as a developer for 30 seconds, methyl isobutyl carbinol (MIBC) Rinse with. An evaluation substrate on which a resist pattern of 40 nm line / 80 nm pitch was formed was obtained by spin-drying by shaking off at 2,000 rpm for 15 seconds.

(Evaluation of resist pattern shape and collapse inhibition)
The shape of the resist pattern and the collapse inhibition property were measured as follows. A scanning electron microscope (“CG-4000” manufactured by Hitachi High-Technologies Corporation) was used for length measurement and observation of the resist pattern on the evaluation substrate.

  In the formation of the resist pattern, the exposure amount is gradually decreased and the exposure is sequentially performed, and the line width corresponding to the minimum exposure amount at which the collapse of the resist pattern is not confirmed is defined as the minimum dimension before collapse (nm). It was used as an index of pattern collapse inhibition. When the dimension before the minimum collapse was 32 nm or less, it was evaluated as “A” (good), when it exceeded 32 nm and 38 nm or less, “B” (somewhat good), and when it exceeded 38 nm, it was evaluated as “C” (bad).

  The resist pattern was evaluated as “A” (good) when the resist pattern was not skirted and “B” (bad) when the pattern was collapsed or skirted.

[Fluorine gas etching removability]
The substrate on which the silicon-containing film obtained above was formed was subjected to CF ₄ = 200 sccm, PRESS. Using an etching apparatus (“TACTRAS” manufactured by Tokyo Electron Ltd.). = 75 mT, HF RF = 250 W, LF RF = 0 W, DCS = -150 V, RDC = 50%, RDC = 50%, etching for 5 seconds, the etching rate (nm / min) is calculated from the average film thickness before and after the treatment, The etching removability with a fluorine-based gas was evaluated. When the etching rate is 60 (nm / min) or more, “A” (good) and when the etching rate is 55 (nm / min) or more and less than 60 (nm / min), “B” (somewhat good) and 55 (nm) / C), it was determined as “C” (defective).

[Oxygen etching resistance]
The substrate on which the silicon-containing film obtained above was formed was etched using an etching apparatus (“TACTRAS” manufactured by Tokyo Electron Ltd.) with O ₂ = 400 sccm, PRESS. = 25 mT, HF RF = 200 W, LF RF = 0 W, DCS = 0 V, RDC = 50%, 60 sec. Etching is performed, and the etching rate (nm / min) is calculated from the average film thickness before and after the treatment. Etching resistance was evaluated. “A” (good) when the etching rate is less than 4.5 (nm / min), and “B” (somewhat better) when the etching rate is 4.5 (nm / min) or more and less than 5.0 (nm / min) ) And 5.0 (nm / min) or more, it was determined as “C” (defective).

  From the results of Table 3, according to the resist process film forming material of the example, in addition to substrate reflectivity and solvent resistance, resist pattern collapse inhibition, resist pattern shape, fluorine-based gas etching removability and oxygen etching resistance It can be seen that a silicon-containing film excellent in all of the above can be formed.

The film forming material for a resist process according to the present invention can be suitably used as a material for forming various silicon-containing films such as a resist intermediate film in a resist process.

Claims (7)

A film forming material for a resist process, comprising a polymer having a structure represented by the following formula (1) and an organic solvent.

(In the formula (1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms including an oxygen atom (excluding a hydrocarbyloxy group), and the ratio of the number of oxygen atoms in R ^{1 to} the number of carbon atoms is 0.35 or more. It is.
R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, or a hydroxy group. a is 0, 1 or 2. When a is 2, the plurality of R ² may be the same or different. When a is 2, a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (except for those corresponding to R ¹ above).
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to the above R ¹ ), a hydrogen atom or a hydroxy group. b is 0, 1 or 2; When b is 2, the plurality of R ⁴ may be the same or different. If b is 2, a plurality of R ⁴ may be combined together, may form a ring structure ring members 3 to 20 together with the silicon atom to which they are attached.
R ⁵ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to R ¹ and those corresponding to R ³ ), a hydrogen atom or a hydroxy group. c is an integer of 0-3. When c is 2 or more, the plurality of R ⁵ may be the same or different. When c is 2 or more, a plurality of R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
d represents the molar ratio of the structural unit U _x to all structural units constituting the polymer.
e represents a molar ratio of structural units U _Y to the total structural units constituting the polymer.
f represents the molar ratio of structural units U _Z to the total structural units constituting the polymer.
d, e, and f satisfy 0 <d ≦ 0.55, 0 ≦ e <0.55, and 0.45 ≦ f <1, respectively, and d + e + f ≦ 1. The structural unit U _x , the structural unit U _Y and the structural unit U _Z are different from each other. )   The film forming material for a resist process according to claim 1, wherein e in the formula (1) satisfies 0 <e <0.5. 3. The film forming material for a resist process according to claim 1, wherein the ratio of the number of oxygen atoms to the number of carbon atoms in R ¹ of the formula (1) is 0.45 or more.   The film forming material for a resist process according to claim 1, wherein f in the formula (1) satisfies 0.55 ≦ f <1. The film forming material for a resist process according to any one of claims 1 to 4,
Forming a silicon-containing film on at least one surface side of the substrate;
A step of forming a resist film on the side of the silicon-containing film opposite to the substrate by using a radiation-sensitive resin composition containing a polymer having an acid-dissociable group and a radiation-sensitive acid generator;
Exposing the resist film;
And a step of developing the exposed resist film.   The pattern forming method according to claim 5, wherein the development of the resist film is performed with an organic solvent-containing liquid. The polymer which has a structural unit represented by following formula (1).

(In the formula (1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms including an oxygen atom (excluding a hydrocarbyloxy group), and the ratio of the number of oxygen atoms in R ^{1 to} the number of carbon atoms is 0.35 or more. It is.
R ² is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, or a hydroxy group. a is 0, 1 or 2. When a is 2, the plurality of R ² may be the same or different. When a is 2, a plurality of R ² may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (except for those corresponding to R ¹ above).
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to the above R ¹ ), a hydrogen atom or a hydroxy group. b is 0, 1 or 2; When b is 2, the plurality of R ⁴ may be the same or different. If b is 2, a plurality of R ⁴ may be combined together, may form a ring structure ring members 3 to 20 together with the silicon atom to which they are attached.
R ⁵ is a monovalent organic group having 1 to 20 carbon atoms (excluding those corresponding to R ¹ and those corresponding to R ³ ), a hydrogen atom or a hydroxy group. c is an integer of 0-3. When c is 2 or more, the plurality of R ⁵ may be the same or different. When c is 2 or more, a plurality of R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the silicon atom to which they are bonded.
d represents the molar ratio of the structural unit U _x to all structural units constituting the polymer.
e represents a molar ratio of structural units U _Y to the total structural units constituting the polymer.
f represents the molar ratio of structural units U _Z to the total structural units constituting the polymer.
d, e, and f satisfy 0 <d ≦ 0.55, 0 ≦ e <0.55, and 0.45 ≦ f <1, respectively, and d + e + f ≦ 1. Structural units Ux, the structural unit _{U Y} and structural units _{U Z} different. )