JP6897071B2 - Film forming material for resist process, pattern forming method and polymer - Google Patents

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 laminated on a substrate to be processed via an organic antireflection film and a silicon-containing film is exposed and developed, and the obtained resist pattern is used as a mask for etching. The process is heavily used. In recent years, as the resist pattern has become finer, the resist pattern has become a problem of collapse, deterioration of rectangularness, and the like. Therefore, it is required to suppress the collapse of the resist pattern and maintain a good shape. Here, conventionally, a material for a silicon-containing film that improves the shape of a resist pattern and a method for forming a pattern on a substrate using such a material for a silicon-containing film have been studied (Japanese Patent Laid-Open No. 2004-310019). See Gazette, International Publication No. 2012/039337).

Japanese Unexamined Patent Publication No. 2004-310019 International Publication No. 2012/0393337

However, when the line width of the resist pattern is reduced to 40 nm or less, the conventional silicon-containing film cannot satisfy these requirements. Further, as the resist pattern becomes finer, the silicon-containing film is also required to be made thinner, so that it is necessary to further enhance the oxygen etching resistance. Further, since 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 forming the pattern of the silicon-containing film using the resist pattern as a mask, fluorine in the silicon-containing film is used. It is also necessary to improve the system gas etching removability.

The present invention has been made based on the above circumstances, and an object of the present invention is to form a silicon-containing film having excellent resist pattern shape and collapse suppressing property, fluorine-based gas etching removability, and oxygen etching resistance. It is an object of the present invention to provide a film-forming material for a resist process capable of forming a film, a pattern forming method using the same, and a polymer suitable as 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。） The present invention made to solve the above problems is a film-forming material for a resist process containing a polymer having a structure represented by the following formula (1) and an organic solvent.

In equation (1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms including an oxygen atom (excluding the hydrocarbyloxy group), and the ^{ratio of the oxygen atom number in R 1 to} the carbon atom number (hereinafter, “O /”). Also referred to as "C ratio") is 0.35 or more. Here, the "organic group" means 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 ^2s may be the same or different. when a is 2, the plurality of R ² may be combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (excluding those corresponding to ^{R 1 above).}
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms ( ^{excluding those corresponding to R 1} above), a hydrogen atom or a hydroxy group. b is 0, 1 or 2. When b is 2, the plurality of R ^4s 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 above), a hydrogen atom or a hydroxy group. c is an integer from 0 to 3. When c is 2 or more, the plurality of R ^5s may be the same or different. If c is 2 or more, plural R ^5, are combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the polymer.
e represents the molar ratio _{of the structural unit U Y} to all the 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 Ux, the structural unit U _Y, and the structural unit U _Z are different from each other. )

Another invention made to solve the above problems is a step of forming a silicon-containing film on at least one surface side of a substrate by the film-forming material for a resist process, a polymer having an acid dissociable group, and a polymer having an acid dissociable group. A step of forming a resist film on the surface side of the silicon-containing film opposite to the substrate by a radiation-sensitive resin composition containing a radiation-sensitive acid generator, a step of exposing the resist film, and the exposure. This is a pattern forming method including a step of developing the resist film. The "acid dissociative group" refers to 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 equation (1),
R ¹ is a monovalent organic group having 1 to 6 carbon atoms including an oxygen atom (excluding the 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 ^2s may be the same or different. when a is 2, the plurality of R ² may be combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (excluding those corresponding to ^{R 1 above).}
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms ( ^{excluding those corresponding to R 1} above), a hydrogen atom or a hydroxy group. b is 0, 1 or 2. When b is 2, the plurality of R ^4s 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 above), a hydrogen atom or a hydroxy group. c is an integer from 0 to 3. When c is 2 or more, the plurality of R ^5s may be the same or different. If c is 2 or more, plural R ^5, are combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the polymer.
e represents the molar ratio _{of the structural unit U Y} to all the 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 Ux, the structural unit U _Y, and the structural unit U _Z are different from each other. )

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

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

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

<[A] Polymer>
The polymer [A] 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 including an oxygen atom (excluding the 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 ^2s may be the same or different. when a is 2, the plurality of R ² may be combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (excluding those corresponding to ^{R 1 above).}
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms ( ^{excluding those corresponding to R 1} above), a hydrogen atom or a hydroxy group. b is 0, 1 or 2. When b is 2, the plurality of R ^4s 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 above), a hydrogen atom or a hydroxy group. c is an integer from 0 to 3. When c is 2 or more, the plurality of R ^5s may be the same or different. If c is 2 or more, plural R ^5, are combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the [A] polymers.
e represents the molar ratio _{of the structural unit U Y} to all the structural units constituting the [A] polymer.
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. The structural unit Ux, the structural unit U _Y, and the structural unit U _Z are different from each other.

The molar ratio of each structural unit in the [A] polymer can be regarded as 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 the resist film formed on the silicon-containing film after the silicon-containing film is formed from the film-forming material containing the polymer, the shape of the resist pattern becomes better. The collapse suppressing property of the resist pattern is further improved, and the fluorine-based 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] polymer to have a structural unit U _x, thereby improving the fluorine-based gas etching removal of the silicon-containing film, which shape of the resist pattern is improved, also improved collapse inhibitory resist pattern It is inferred that.

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 including an oxygen atom (excluding the 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 ^2s may be the same or different. when a is 2, the plurality of R ² may be combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the [A] polymers.

^{As a monovalent organic group having 1 to 6 carbon atoms containing an oxygen atom represented by R 1} of the above formula (U-1), for example, the carbon of a monovalent hydrocarbon group having 1 to 6 carbon atoms- A group having one or more linking groups containing oxygen atoms between carbons, a group in which one or more hydrogen atoms of a monovalent hydrocarbon group having 1 to 6 carbon atoms are substituted with a monovalent substituent containing an oxygen atom. And so on. Some or all of the hydrogen atoms of these hydrocarbon groups may be substituted with arbitrary substituents, and between the carbons of these hydrocarbon groups, a sulfide group (-S-) or the like may be used. It may contain a linking group that does not contain an oxygen atom.

Here, the "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group. This "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 contain a cyclic structure and is composed only of a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The "alicyclic hydrocarbon group" refers to a hydrocarbon group containing only an alicyclic structure as a cyclic structure and not containing an aromatic ring structure. However, it does not have to be composed only of an alicyclic structure, and a chain structure may be included as a part thereof. The "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a cyclic structure. However, it does not have to be composed only of an aromatic ring structure, and a chain structure or an alicyclic structure may be included as a part thereof. In the present invention, ^{as the hydrocarbon group in R 1} , a chain hydrocarbon group or an alicyclic hydrocarbon group is preferable.

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-), and a sulfonyl group (-SO-). -SO _2- ), 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 containing no oxygen atom among the above-mentioned arbitrary 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. Be done.

The carbon atom number of the monovalent organic group represented by R ^1, in order to increase the oxygen etching resistance and fluorine gas etching removal property, 1-5, more preferably 1 to 4, 1 to 3 further Preferably, 1 and 2 are particularly preferred.

As the oxygen atoms of the monovalent organic group represented by R ^1, in order to increase the oxygen etching resistance and fluorine gas etching removal property, 1-5, more preferably 1 to 4, 1 to 3 further preferable.

The lower limit of the O / C ratio of 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, as the upper limit, 3 is preferable, 2 is more preferable, and 1.5 is particularly preferable.

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.

The monovalent chain hydrocarbon group having 1 to 20 carbon atoms includes a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group and a 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.

Hydrocarbyloxy groups having 1 to 20 carbon atoms include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, 2-methylpropoxy group, 1-methylpropoxy group and t-butoxy group. , N-hexyloxy group, n-heptyloxy group, n-octyloxy group and the like.

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

Structural units U _X, for example the R ¹ in the formula (1), obtained by hydrolytic condensation of silane monomer having a hydrolyzable group bonded to a silicon atom (I). Examples of the hydrolyzable group include an alkoxy group such as a methoxy group and an ethoxy group, an asyloxy group such as an acetoxy group, and a halogen atom such as a chlorine atom.

Specific examples of the silane monomer (I) include compounds represented by the following formulas (i-1) to (i-13), respectively. The silane monomer (I) may be used alone or in admixture of a plurality of types.

[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, as the upper limit, 0.5 is preferable, 0.45 is more preferable, and 0.4 is further preferable. The molar ratio d of the structural unit U _X within the above lower limit or more, it is possible to increase the fluorine-based gas etching removability. 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 _UZ ]
The structural unit U _Z 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 by 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 R 1} and R ³ above), a hydrogen atom or a hydroxy group. c is an integer from 0 to 3. When c is 2 or more, the plurality of R ^5s may be the same or different. If c is 2 or more, plural R ^5, are combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
f represents the molar ratio of structural units U _Z to the total structural units constituting the [A] polymers.

The monovalent organic group having 1 to 20 carbon atoms represented by ^{R 5 corresponds to, for example, R 1} and R ³ from the monovalent organic group having 1 to 20 carbon atoms exemplified in ^{R 2.} Examples include those excluding the group.

As the R ^5, preferably a monovalent chain-like hydrocarbon group having 1 to 20 carbon atoms, a monovalent more preferably chain hydrocarbon group, an ethyl group and methyl group of 1 to 4 carbon atoms further Preferably, a methyl group is particularly preferred.

As c in the above formula (U-3), 0 and 1 are preferable, and 0 is more preferable. By setting c to 0, the silicon content ratio of the polymer [A] can be increased, and the solvent resistance, oxygen etching resistance, and the like of the silicon-containing film formed by 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, as the upper limit, 0.95 is preferable, 0.9 is more preferable, 0.85 is further preferable, and 0.8 is particularly preferable. 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 U _Y is a structural unit represented by the following formula (U-2). [A] Since the polymer has the structural unit U _Y, it is possible to enhance the antireflection property from the silicon-containing film during exposure when forming a resist pattern, and suppress interference due to reflected light during exposure. The polymer [A] preferably contains the structural unit Uy because the shape of the resist pattern becomes better.

In the above formula (U-2),
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (excluding those corresponding to ^{R 1 above).}
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms ( ^{excluding those corresponding to R 1} above), a hydrogen atom or a hydroxy group. b is 0, 1 or 2. When b is 2, the plurality of R ^4s 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 the molar ratio _{of the structural unit U Y} to all the structural units constituting the [A] polymer.

Examples of the ^{monovalent organic group having 6 to 20 carbon atoms including the aromatic ring represented by R 3} include an aromatic group having 6 to 20 carbon atoms and an aromatic group having 6 to 20 carbon atoms such as an aralkyl group. Examples include hydrocarbon groups. This aromatic hydrocarbon group may have a substituent.

Examples of the aryl group include a phenyl group, a tolyl group, a xsilyl group, a naphthyl group, an anthrasenyl group and the like.

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

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.

As the R ^3, preferably an aryl group having 6 to 20 carbon atoms, a phenyl group, methylphenyl group, and a fluorophenyl group are more preferable.

As the monovalent organic group having 1 to 20 carbon atoms represented by ^{R 4} , for example, the group corresponding ^{to R 1} is excluded from the monovalent organic group having 1 to 20 carbon atoms exemplified in ^{R 2.} And so on.

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

_{[A] As the lower limit of the molar ratio e of the structural unit U Y} to all the structural units constituting the polymer, 0.01 is preferable, 0.05 is more preferable, 0.08 is further preferable, and 0.1 is particularly preferable. preferable. On the other hand, as the upper limit, 0.4 is preferable, 0.3 is more preferable, 0.25 is further preferable, and 0.2 is particularly preferable. By setting the molar ratio e of the structural unit U _Y to be equal to or greater than the above lower limit and equal to or less than the above upper limit, the antireflection property, the shape of the resist pattern, the collapse suppressing property, and the like can be exhibited in a better and well-balanced manner.

[Other structural units]
[A] The polymer, the structural unit U _X, may have other structural units other than 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, and polydimethoxymethylcarbosilane. When the [A] polymer has other structural units, the upper limit of the molar ratio of the other structural units to all the 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, further preferably 80% by mass, and particularly 90% by mass, based on the total solid content of the film-forming material. preferable. By setting the content of the polymer [A] to the above lower limit or more, the shape and collapse suppressing property of the resist pattern, the fluorine-based gas etching removability of the silicon-containing film, and the oxygen etching resistance 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. The polymer [A] may contain only one type or two or more types.

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

As the Mw of the [A] polymer in the present specification, a GPC column (2 “G2000HXL”, 1 “G3000HXL” and 1 “G4000HXL”) manufactured by Toso Co., Ltd. is used, and the elution solvent: tetrahydrofuran, flow rate: 1. It is a value measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under analytical conditions of 0 mL / min and a column temperature of 40 ° C.

The polymer [A] can be obtained by the method of hydrolyzing and condensing the 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, more preferably 5% by mass. An alcohol solvent having a boiling point of 100 ° C. or lower may be generated during hydrolysis and condensation of each of the above silane monomers, and the content of the alcohol 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>
As the [B] organic solvent, any solvent can be used as long as it can dissolve or disperse the [A] polymer and arbitrary components.

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

Examples of alcohol-based solvents include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, and the like. sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol , Se-octanol, n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol , Methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, phenylmethylcarbinol, diacetone alcohol, cresol and other monoalcoholic solvents;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptandiol, 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 and methyl-n-. Examples thereof include hexyl ketone, di-i-butyl ketone, trimethylnonanone, cyclohexanone, methylcyclohexanone, 2,4-pentandione, acetonylacetone, diacetone alcohol, acetophenone and fenchone.

Examples of the ether solvent include diethyl ether, ethyl methyl ether, ethylene oxide, 1,2-propylene oxide, dioxolane, 4-methyldioxolane, dioxane, dimethyldioxane, 2-methoxyethanol, 2-ethoxyethanol, ethylene glycol diethyl ether, and the like. 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-hexyl ether, ethoxytriglycol, tetraethylene glycol di-n-butyl ether, 1-n-butoxy-2-propanol, 1-phenoxy-2-propanol, Propropylene 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-methyl tetrahydrofuran, etc. Can be mentioned.

Examples of the ester solvent 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, and the like. N-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, aceto Ethyl acetate, ethylene glycol monomethyl ether acetate, 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 acetate Glycol monopropyl ether, 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, dimethyl phthalate, diethyl phthalate and the like.

[B] Among the organic solvents, an ether solvent and an ester solvent are preferable, and an ether solvent having a glycol structure and an ester solvent are more preferable.

Examples of the ether solvent and ester solvent 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, and propylene glycol monopropyl acetate. Examples include ether.

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

The lower limit of the content of the [B] organic solvent in the film-forming material is preferably 90% by mass, more preferably 92% by mass, and even more preferably 96% by mass. The upper limit of the content is preferably 99.5% by mass, more preferably 99.0% by mass.

<[C] Water>
The film-forming material may contain [C] water, if 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 at the time of film formation is promoted, and a more dense 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 0. 3% by mass is more preferable. The upper limit of the content is preferably 10% by mass, more preferably 5% by mass, further 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 the [D] nitrogen-containing compound, the ability to suppress the collapse of the resist pattern can be further improved. In addition, curing at the time of film formation progresses, and the strength of the obtained silicon-containing film can be further increased. [D] As the nitrogen-containing compound, only one kind may be used, or two or more kinds may be used in combination.

[D] As the nitrogen-containing compound, in order to promote the above-mentioned cross-linking reaction, a compound having a basic amino group and a compound that produces a basic amino group by the action of an acid or heat are preferable.

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

Examples of amine compounds include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylaniline 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.

Examples of the amide group-containing compound include N-t-butoxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonyl-2-carboxy-4-hydroxypyrrolidine, Nt-butoxycarbonyl-2-carboxypyrrolidine and the like. -T-Butoxycarbonyl group-containing amino compounds;
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, etc. Can be mentioned.

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

When the film-forming material contains the [D] nitrogen-containing compound, the lower limit of the content of the [D] nitrogen-containing compound is preferably 0.1 part by mass with respect to 100 parts by mass of the [A] polymer. 1 part by mass is more preferable, and 3 parts by mass is further preferable. The upper limit of the content is preferably 30 parts by mass, more preferably 15 parts by mass, and even more preferably 10 parts by mass. [D] By setting the content of the nitrogen-containing compound to be equal to or higher than the above lower limit and equal to or lower than the above upper limit, the ability to suppress collapse of the resist pattern can be further improved.

<[E] Acid generator>
[E] The acid generator is a compound that generates an acid by irradiation with radiation such as ultraviolet rays and / or heating. When the film-forming material contains the [E] acid generator, curing during 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. It can increase resistance. Examples of the [E] 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, and 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 Difluoroethan sulfonate, triphenyl sulfonium N, N'-bis (nonafluoro-n-butane sulfonyl) immunodate, triphenyl sulfonium salicylate, triphenyl sulfonium camphor sulfonate, triphenyl sulfonium tricyclo [3.3.1.1 ^{3, 7} ] Triphenylsulfonium salts such as decanyldifluoromethanesulfonate;
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-cyclohexylphenyldiphenylsulfonium N, N'-bis (nonafluoro-n-butanesulfonyl) imidazolate, 4-cyclohexylphenyldiphenylsulfonium such as 4-cyclohexylphenyldiphenylsulfonium camphorsulfonate. salt;
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-butylphenyldiphenylsulfonium2- (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 4-t-Butylphenyldiphenylsulfonium salt such as phenyldiphenylsulfonium camphorsulfonate;
Tri (4-t-butylphenyl) sulfonium trifluoromethanesulfonate, tri (4-t-butylphenyl) sulfonium nonafluoro-n-butane sulfonate, tri (4-t-butylphenyl) sulfonium perfluoro-n-octane sulfonate, 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 - Examples thereof include tri (4-t-butylphenyl) sulfonium salts such as n-butanesulfonyl) imidazole and tri (4-t-butylphenyl) sulfonium sulfonium sulfonate.

Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, and 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) immediate, diphenyliodonium camphorsulfonate;
Bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butane sulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octane sulfonate, 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 Examples thereof include bis (4-t-butylphenyl) iodonium salt such as −n-butanesulfonyl) imidazole and bis (4-t-butylphenyl) iodonium camphor sulfonate.

Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) succinimide, N- (nonafluoro-n-butanesulfonyloxy) succinimide, N- (perfluoro-n-octanesulfonyloxy) succinimide, and 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- (kanfersulfonyloxy) succinimide compounds such as succinimide;
N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-en-2,3-dicarboxyimide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [2.2.1] hept -5-en-2,3-dicarboxyimide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] Hept-5-en-2,3-dicarboxyimide, 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 -5 -En-2,3-dicarboxyimide, N- (campersulfonyloxy) bicyclo [2.2.1] hept-5-en-2,3-dicarboxyimide and other bicyclo [2.2.1] hept Examples thereof include -5-ene-2,3-dicarboxyimide compounds.

Only one kind of these [E] acid generators may be used, or two or more kinds thereof may be used in combination.

[E] As the acid generator, an onium salt is preferable, and a sulfonium salt is more preferable.

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, and 0. 1 part by mass is more preferable, 0.5 part by mass is further preferable, and 1 part by mass is particularly preferable. The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass, and even more preferably 5 parts by mass. [E] By setting the content of the acid generator to be equal to or higher than the above lower limit and equal to or lower than the above upper limit, the ability to suppress the collapse of the resist pattern can be further improved.

<Other optional ingredients>
The film-forming material may contain other optional components in addition to the above-mentioned [A] to [E] components. Other optional components include, for example, surfactants, colloidal silica, colloidal alumina, organic polymers and the like. When the film-forming material contains other optional components, the upper limit of the content is preferably 2 parts by mass and more preferably 1 part by mass with respect to 100 parts by mass of the [A] polymer.

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

The lower limit of the solid content concentration of the film-forming material is preferably 0.01% by mass, more preferably 0.1% by mass, further preferably 0.5% by mass, and particularly preferably 1% by mass. 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 firing 0.5 g of the film-forming material at 250 ° C. for 30 minutes. Value (mass%).

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

The silicon-containing film is formed by applying the above-mentioned film-forming material to the surface of a substrate or another underlayer film such as an organic underlayer film, and the coating film is heat-treated and cured. Can be formed by

Examples of the method for applying the film-forming material include a spin coating method, a roll coating method, and a dip method. The temperature of the heat treatment is usually 50 ° C. or higher and 550 ° C. or lower. As the lower limit of the average thickness of the silicon-containing film formed, 5 nm is preferable, and 10 nm is more preferable. 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 (reversal pattern) forming material obtained through an inversion process.

<Pattern formation method>
The pattern forming method includes a step of forming a silicon-containing film on at least one surface side of the substrate by the film-forming material (hereinafter, also referred to as a "silicon-containing film forming step") and a weight having an acid dissociable group. A step of forming a resist film on the surface side of the silicon-containing film opposite to the substrate by the radiation-sensitive resin composition containing the coalesced and radiation-sensitive acid generator (hereinafter, also referred to as "resist film forming 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 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”) before the silicon-containing film forming step. After the development step, a step of etching the silicon-containing film or the organic underlayer film (hereinafter, also referred to as “etching step”) may be provided using the resist pattern as a mask. Hereinafter, each step will be described.

(Organic underlayer film 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, and a resin substrate. For example, an interlayer insulating film such as a wafer coated with a low dielectric insulating film formed of "Black Diamond" of AMAT, "Silk" of Dow Chemical, "LKD5109" of JSR, etc. can be used. As this substrate, a patterned substrate such as a wiring groove (trench) and 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 function of the silicon-containing film and / or the resist film in resist pattern formation and to obtain a function that these films do not have. It is a film that imparts properties, flatness of the coating film, and high etching resistance to fluorine-based gas).

Examples of the organic underlayer film include an antireflection film and the like. Examples of the antireflection film forming composition 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 the film.

(Silicon-containing film forming process)
In this step, a silicon-containing film is formed on at least one surface side of the substrate by 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. As a result, it is possible to obtain a substrate with a silicon-containing film in which a silicon-containing film is formed on the substrate.

The method for forming the silicon-containing film is not particularly limited, but for example, a coating film formed by applying the film-forming material onto a 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-ray, electron beam, γ-ray, molecular beam, ion beam and the like. As the lower limit of the temperature when heating the coating film, 50 ° C. is preferable, 90 ° C. is more preferable, 150 ° C. is further preferable, and 200 ° C. is particularly preferable. The upper limit of the temperature is preferably 550 ° C, more preferably 450 ° C, even more preferably 400 ° C, and particularly preferably 300 ° C. The lower limit of the average thickness of the silicon-containing film formed is preferably 5 nm, more preferably 10 nm, and even more preferably 12 nm. As the upper limit, 200 nm is preferable, 100 nm is more preferable, 40 nm is further preferable, and 30 nm is particularly preferable.

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

The resist composition used for forming the resist film is a positive type including a polymer having an acid dissociative group, a radiation-sensitive resin composition containing a radiation-sensitive acid generator, an alkali-soluble resin, and a quinonediazide-based photosensitizer. Examples thereof include a negative resist composition containing a resist composition, an alkali-soluble resin and a cross-linking agent, and the above-mentioned radiation-sensitive resin composition is preferable. When the above-mentioned 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 forming 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 appropriately used.

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. Further, as the resist composition, one filtered using a filter having a pore size of about 0.2 μm can be preferably used. 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 of applying the resist composition is not particularly limited, and the resist composition 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 obtained resist film has a predetermined film thickness.

The resist film can be formed by volatilizing the solvent in the coating film by prebaking the coating film formed by applying the resist composition. The prebake temperature is appropriately adjusted according to the type of resist composition used and the like, but the lower limit of the prebake temperature is preferably 30 ° C., more preferably 50 ° C. The upper limit of the temperature is preferably 200 ° C., more preferably 150 ° C.

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

The radiation used for the above exposure includes visible light, ultraviolet rays, far ultraviolet rays, X-rays, electron beams, γ-rays, molecular beams, ion beams, etc., depending on the type of acid generator used in the resist composition. Although is suitably selected from, among these, far ultraviolet rays are preferred, 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 rays (wavelength of 13 nm, etc.) are more preferable. Further, the exposure method is not particularly limited, and the exposure method can be performed according to 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 alkaline development or organic solvent development, but in the case of organic solvent development, the shape of the resist pattern becomes better, and the resist pattern collapse inhibitory property can be further improved.

Examples of the developing solution used for alkaline 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-An aqueous solution of nonen or the like can be mentioned. Further, these aqueous solutions may be prepared by adding an appropriate amount of a water-soluble organic solvent, for example, alcohols such as methanol and ethanol, and a surfactant.

Examples of the organic solvent developing solution 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 [B] organic solvent. These solvents may be used alone, in combination of two or more, or mixed 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 is made more hydrophilic by the acid generated by the acid generator. Therefore, the adhesion between the resist film and the silicon-containing film is high with respect to the organic solvent which is the developing solution, and the ability to suppress the collapse of the resist pattern can be further improved.

A predetermined resist pattern corresponding to a photomask can be formed by washing and drying after developing with a developing solution.

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

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

The dry etching can be performed using a known dry etching apparatus. The source gas during dry etching depends on the elemental composition of the film to be etched, but is, for example, a fluorogas such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ , Cl ₂ , Chlorine-based gas such as BCl ₃ , oxygen-based gas such as _{O 2} , 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 gases such as H ₄ , C ₃ H ₆ , C ₃ H ₈ , HF, HI, HBr, HCl, NO, NH ₃ , BCl _{3 and inert gases such as He, N 2} , Ar are used. These gases can be mixed and used. A fluorine-based gas is usually used for dry etching of the silicon-containing film, and a mixture of an oxygen-based gas and an inert gas is preferably used.

When a substrate on which an organic underlayer film is formed is used, 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 each of the above steps.

<Silicon-containing film removal process>
In this step, the pattern is formed by the pattern forming method, the substrate to be processed is treated, and then the silicon-containing film is removed by dry etching. The dry etching can be performed using a known dry etching apparatus. As the source gas for dry etching, for example, fluorogas such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ and chlorine gas such as Cl ₂ and BCl _{3 are used.} , These gases can be mixed and used.

<Polymer>
The polymer according to one embodiment of the present invention is a polymer having a structure represented by the above formula (1). The details of the polymer are as described above as the [A] polymer which is a component of the “resist process film-forming material”, and the description thereof will be omitted here. The polymer can be suitably used as a component of a film-forming material for a resist process.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The solid content concentration of the polymer solution and the weight average molecular weight (Mw) of the polymer [A] in this example were measured by the following methods.

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

[Weight average molecular weight (Mw)]
Using Toso's GPC columns (2 "G2000HXL", 1 "G3000HXL" and 1 "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] The silane monomer used for the synthesis of the polymer is 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 solution of oxalic acid was prepared by mixing 5.93 g of a 10 mass% aqueous solution of oxalic acid dihydrate and 3.56 g of water. Then, 12.38 g (66 mol%) of compound (M-1), 2.50 g (14 mol%) of compound (M-2), 4.00 g (20 mol%) of compound (M-4) and methanol 11. A cooling tube and a dropping funnel containing the above-prepared oxalic acid aqueous solution were set in a flask containing 62 g. Next, the flask was heated to 60 ° C. in an oil bath, and then the aqueous oxalic acid solution was slowly added dropwise, and the flask was reacted at 60 ° C. for 4 hours. After completion of the reaction, the flask containing the reaction solution was allowed to cool, replaced with propylene glycol monomethyl ether acetate, set in an evaporator, and methanol was removed to obtain 74 g of a resin solution. The solid content in this resin solution is designated as a polymer (A-1). The content ratio of the solid content in the obtained resin solution was 9.8% by mass. The 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) Synthetic)
Polymers (A-2) to (A-8) and polymers (a-1) were prepared in the same manner as in Example 1 except that the types and amounts of silane monomers shown in Table 1 below 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 also shown in Table 1. The numerical values shown in parentheses in the columns of M-4 to M-11 in Table 1 are the O / C ratios of the compounds (M-4) to (M-11).

In Table 1 below, in the polymer (a-1), the amount of the compound (M-1) that gives the structural unit Uz is 40 mol%, and f in the above formula (1) is less than 0.45. , It does not correspond to the Example and is referred to as "Synthesis Example 1-1". Further, 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 correspond to the examples and is referred to as “Synthesis Example 1-2”. ..

[Preparation of film-forming material for resist process]
The components other than the [A] polymer used for preparing the film-forming material for the 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. Was mixed, 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 a resist process.

[Examples 2-2-2-8 and Comparative Examples 2-1 and 2-2]
The resist process film-forming materials (J-2) to (J-8) and (j) were prepared 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 above-mentioned film-forming materials for the process obtained above was applied on a silicon wafer by a spin coating method using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited), and then on a hot plate at 220 ° C. for 1 minute. 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. Obtained a substrate. The average thickness of the silicon-containing film was measured with a film thickness measuring device (“M-2000D” manufactured by JA Woollam).

<Evaluation>
The following items were evaluated for the formed silicon-containing film by the method shown below. The evaluation results are shown in Table 3 below.

[Substrate reflectance]
Refractive index parameters (n) and erasure of each of the formed silicon-containing film, underlayer film forming composition (JSR's "NFC HM8006") and radiation-sensitive resin composition (JSR's "ARF AR2772JN"). The refractive index (k) is measured by a high-speed spectroscopic ellipsometer (“M-2000” by JA Woollam), and based on this measured value, simulation software (“Prolis” by KLA-TENCOR) is used. The substrate reflectance of the laminate of the resist film / silicon-containing film / organic underlayer film under the conditions of NA1.3 and Spectro was determined. The substrate reflectance was evaluated as "A" (good) when it was 1% or less, and as "B" (bad) when it exceeded 1%.

[Solvent resistance]
The substrate on which the obtained silicon-containing film was formed was immersed in cyclohexane at room temperature for 10 seconds. The average thickness of the silicon-containing film before and after immersion 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 rate of change in film thickness (%) due to solvent immersion was calculated 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 film thickness change rate was less than 1%, and as "B" (poor) when the film thickness change rate was 1% or more.

[Resist pattern collapse inhibitory property and resist pattern shape]
The collapsing inhibitory property of the resist pattern and the shape of the resist pattern were evaluated by performing the lithography evaluation shown below.

(Lilithography evaluation, organic solvent development)
An organic underlayer film forming material (JSR's "NFC HM8006") 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. .. The obtained film-forming material for the resist process is spin-coated on the organic underlayer film with the spin coater, heat-treated at 220 ° C. for 60 seconds, and then cooled at 23 ° C. for 60 seconds to achieve an average thickness of 25 nm. Silicon-containing film was formed. Next, a radiation-sensitive resin composition (JSR's "ARF AR2772JN") is spin-coated on this silicon-containing film by the spin coater, heat-treated at 90 ° C. for 60 seconds, and then cooled at 23 ° C. for 30 seconds. 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 optical conditions of NA: 1.30 and Dipole. Post-bake at 100 ° C. for 60 seconds on a "Lithius Pro-i" hot plate, cool at 23 ° C. for 30 seconds, paddle-develop with butyl acetate as a developer for 30 seconds, and methylisobutylcarbinol (MIBC). Rinse with. By spin-drying at 2,000 rpm for 15 seconds with shaking off, an evaluation substrate on which a resist pattern of 40 nm line / 80 nm pitch was formed was obtained.

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

In the formation of the resist pattern, the exposure amount is gradually reduced and the resist is sequentially exposed, 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 pre-collapse dimension (nm) and the resist is formed. It was used as an index of pattern collapse suppression. When the minimum pre-collapse dimension was 32 nm or less, it was evaluated as "A" (good), when it exceeded 32 nm and 38 nm or less, it was evaluated as "B" (slightly good), and when it exceeded 38 nm, it was evaluated as "C" (defective).

The shape of the resist pattern was evaluated as "A" (good) when the resist pattern had no hemming, and as "B" (poor) when the resist pattern had collapsed or hemming.

[Fluorine-based gas etching removability]
The substrate on which the obtained silicon-containing film was formed was subjected to CF ₄ = 200 sccm, PRESS. Etching treatment was performed under the conditions of = 75 mT, HF RF = 250 W, LF RF = 0 W, DCS = -150 V, RDC = 50%, 5 sec, and the etching rate (nm / min) was calculated from the average film thickness before and after the treatment. The etching removability by the fluorine-based gas was evaluated. When the etching rate is 60 (nm / min) or more, it is "A" (good), and when it is 55 (nm / min) or more and less than 60 (nm / min), it is "B" (slightly good) and 55 (nm). If it was less than / minute), it was rated as "C" (defective).

[Oxygen etching resistance]
The substrate on which the obtained silicon-containing film was formed was subjected to O ₂ = 400 sccm, PRESS. Etching treatment is performed under the conditions of = 25 mT, HF RF = 200 W, LF RF = 0 W, DCS = 0 V, RDC = 50%, 60 sec, and the etching rate (nm / min) is calculated from the average film thickness before and after the treatment to obtain oxygen. Etching resistance was evaluated. If the etching rate is less than 4.5 (nm / min), it is "A" (good), and if it is 4.5 (nm / min) or more and less than 5.0 (nm / min), it is "B" (slightly good). ) And 5.0 (nm / min) or more, it was evaluated as "C" (defective).

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

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 (8)

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

(In equation (1),
R ¹ is a monovalent organic group having 1 to 4 carbon atoms containing an oxygen atom (excluding a group containing a sulfonyl group and a hydrocarbyloxy group), and the ^{number of carbon atoms in R 1} is the number of carbon atoms of the oxygen atom. The ratio to 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 ^2s may be the same or different. when a is 2, the plurality of R ² may be combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (excluding those corresponding to ^{R 1 above).}
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms ( ^{excluding those corresponding to R 1} above), a hydrogen atom or a hydroxy group. b is 0, 1 or 2. When b is 2, the plurality of R ^4s 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 above), a hydrogen atom or a hydroxy group. c is an integer from 0 to 3. When c is 2 or more, the plurality of R ^5s may be the same or different. If c is 2 or more, plural R ^5, are combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the polymer.
e represents the molar ratio _{of the structural unit U Y} to all the 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. ) R of the above formula (1) ¹ Is a group having one linking group containing an oxygen atom between one or more sets of monovalent hydrocarbon groups and a monovalent hydrocarbon group containing an oxygen atom, or a monovalent substituent containing an oxygen atom. Is a group substituted with one or more hydrocarbon atoms of
The linking group containing an oxygen atom is an ether group, a carbonyl group or an ester group.
The film-forming material for a resist process according to claim 1, wherein the monovalent substituent containing an oxygen atom is a hydroxy group, a carboxy group, a formyl group or a group represented by -OC (= O) H. The film-forming material for a resist process according to claim 1 or 2 , wherein e of the above formula (1) satisfies 0 <e <0.5. The film-forming material for a resist process according to claim 1, claim 2 or claim 3 , wherein the ratio of the number of oxygen atoms to the number of carbon atoms in ^{R 1} of the above formula (1) is 0.45 or more. The film-forming material for a resist process according to any one of claims 1 to 4 , wherein f in the above formula (1) satisfies 0.55 ≦ f <1. The film-forming material for the resist process according to any one of claims 1 to 5.
A process of forming a silicon-containing film on at least one surface side of the substrate,
A step of forming a resist film on the surface side of the silicon-containing film opposite to the substrate by using a radiation-sensitive resin composition containing a polymer having an acid dissociative group and a radiation-sensitive acid generator.
The process of exposing the resist film and
A pattern forming method including a step of developing the exposed resist film. The pattern forming method according to claim 6 , wherein the resist film is developed with an organic solvent-containing liquid. A polymer having a structural unit represented by the following formula (1).

(In equation (1),
R ¹ is a monovalent organic group having 1 to 4 carbon atoms containing an oxygen atom (excluding a group containing a sulfonyl group and a hydrocarbyloxy group), and the ^{number of carbon atoms in R 1} is the number of carbon atoms of the oxygen atom. The ratio to 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 ^2s may be the same or different. when a is 2, the plurality of R ² may be combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
R ³ is a monovalent organic group having 6 to 20 carbon atoms including an aromatic ring (excluding those corresponding to ^{R 1 above).}
R ⁴ is a monovalent organic group having 1 to 20 carbon atoms ( ^{excluding those corresponding to R 1} above), a hydrogen atom or a hydroxy group. b is 0, 1 or 2. When b is 2, the plurality of R ^4s 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 above), a hydrogen atom or a hydroxy group. c is an integer from 0 to 3. When c is 2 or more, the plurality of R ^5s may be the same or different. If c is 2 or more, plural R ^5, are combined with each other, the ring structure of ring members 3-20 and may form together with the silicon atom to which they are attached.
d represents the molar ratio of the structural unit U _x to the total structural units constituting the polymer.
e represents the molar ratio _{of the structural unit U Y} to all the 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 Ux, the structural unit U _Y, and the structural unit U _Z are different from each other. )