JP2005060638A - Polymer, production method, resist composition and method for forming pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polymer useful as a resist material, or the like, especially the polymer as the resist material suitable for a fine processing using an ArF excimer laser or an electron beam, to provide a method for producing the same, to obtain a resist composition by using the same, and to provide a method for forming a pattern. <P>SOLUTION: The polymer contains a constitution unit expressed by formula (1) [wherein, (n) is 0-3 integer; R1 is H or methyl; R2 is a 1-6C straight chain or branched chain alkyl; R3, R4 are each independently H or a 1-4C straight chain or branched chain alkyl, or R3 and R4 together form a 1-6C alkylene chain, O, S or NH; X1, X2 are each a direct bond or a 1-3C alkylene chain; Y1 is O, C(O), O-C(O) or C(O)-O; and also a cycloalkyl ring, alkyl, alkylene, X1 and X2 are each independently a 1-6C straight chain or branched chain alkyl, hydroxy, carboxyl, or the like]. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polymer useful for a resist material and the like, in particular, a polymer for a resist material suitable for microfabrication using an ArF excimer laser or an electron beam, a production method thereof, a resist composition using the polymer, and The present invention relates to a pattern forming method.

  In recent years, in the field of microfabrication in the manufacture of semiconductor elements and liquid crystal elements, miniaturization has rapidly progressed due to advances in lithography technology. As a method for miniaturization, generally, the wavelength of irradiation light emitted from an exposure light source is shortened. Specifically, it is represented by conventional g-line (wavelength: 438 nm) and i-line (wavelength: 365 nm). Irradiation light is changing from ultraviolet rays to DUV (Deep Ultra Violet).

At present, KrF excimer laser (wavelength: 248 nm) lithography technology is introduced into the market, and ArF excimer laser (wavelength: 193 nm) lithography technology for further shortening the wavelength is about to be introduced. Further, as a next-generation technique, an F ₂ excimer laser (wavelength: 157 nm) lithography technique has been studied. In addition, an electron beam lithography technique has been energetically studied as a slightly different type of lithography technique.

  As a high-resolution resist for such short-wavelength irradiation light or electron beam, a “chemically amplified resist” containing a photoacid generator has been proposed. At present, improvement and development of this chemically amplified resist are energetic. It is advanced to.

  Corresponding to the shortening of the wavelength of the irradiation light, the structure of the resin used for the resist has also changed. For example, polyhydroxystyrene used in KrF excimer laser lithography and those whose hydroxyl groups are protected with an acid dissociable, dissolution inhibiting group are not necessarily sufficiently transparent to irradiation light with a wavelength of 193 nm in ArF excimer laser lithography. In many cases, it cannot be used.

Therefore, an acrylic resin that is transparent with respect to irradiation light with a wavelength of 193 nm has attracted attention as a resist resin used in ArF excimer laser lithography. As such an acrylic resin, for example, Patent Document 1, Patent Document 2, Patent Document 3 and the like describe a methacrylic ester of a bridged cyclic saturated hydrocarbon having a lactone ring.
JP 2000-26446 A JP 2002-275215 A However, a resin obtained by copolymerizing these methacrylic acid esters often does not have sufficient solubility in a solvent when preparing a resist solution. Occurrence of the resist increases the number of manufacturing steps, which may hinder the preparation of the resist solution.

  The present invention is a polymer having high transparency with respect to light having a wavelength of 250 nm or less, particularly ArF excimer laser light, and excellent solubility in organic solvents, and a method for producing such a polymer suitable for a resist composition, sensitivity Another object of the present invention is to provide a resist composition suitable for far-ultraviolet excimer laser lithography, electron beam lithography, and the like excellent in dry etching resistance, and a highly accurate fine pattern forming method using the resist composition.

  As a result of intensive studies to achieve the above object, the present inventors have found that a polymer containing a specific monomer constituent unit that is highly transparent to light having a wavelength of 250 nm or less and excellent in solubility in an organic solvent. The present invention has found a resist composition suitable for far-ultraviolet excimer laser lithography, electron beam lithography, etc., which has excellent sensitivity, resolution, and dry etching resistance, and a pattern formation method using this resist composition. Reached.

That is, the first gist of the present invention is the following formula (1).

(In the formula (1), n represents an integer of 0 to 3, R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear or branched alkyl group having 1 to 6 carbon atoms, R ³ , R ⁴ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, or an alkylene chain having 1 to 6 carbon atoms represented by R ³ and R ⁴ , —O—, —S—, or — NH ¹ is formed, X ¹ and X ² represent a direct bond or an alkylene chain having 1 to 3 carbon atoms, and Y ¹ represents an oxygen atom, C (O), O—C (O) or C (O) —O. In addition, the cyclohexyl ring, the alkyl group, the alkylene group, X ¹ and X ² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, and 1 to 6 carbon atoms. Carboxyl group, amino group, cyano esterified with alcohol It may have.)
It is a polymer containing the structural unit represented by these.

The second gist of the present invention is the following formula (2).

(In the formula ^(2), R 1 ~R ^{4 is, X 1, X 2, Y} 1 is as defined for formula (1) ^.R 5 ~R ⁸ each independently represent a hydrogen atom and a A linear or branched alkyl group, a hydroxy group, a carboxy group, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, an amino group or a cyano group, and the linear or branched alkyl having 1 to 6 carbon atoms. The group may have a hydroxy group, a carboxy group, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an amino group, or a cyano group.)
It is a polymer containing the structural unit represented by these.

The third gist of the present invention is the following formula (3).

(In the formula ^{(3), R 1, X} 1, X 2, Y 1 is as defined for formula ^(1), R 5 ~R ⁸ are as defined in the formula (2) .Z is 1 to carbon atoms 3 methylene chains or oxygen atoms.)
It is a polymer containing the structural unit represented by these.

  The fourth gist of the present invention is the polymerization according to any one of claims 1 to 5, wherein the polymerization is carried out while dropping a monomer that becomes a constituent unit of the polymer of the present invention into a polymerization vessel. It is a manufacturing method of coalescence.

  The fifth gist of the present invention is a resist composition containing the polymer.

  The sixth gist of the present invention is a pattern forming method comprising a step of applying the resist composition onto a substrate to be processed, a step of exposing with light having a wavelength of 250 nm or less, and a step of developing using a developer. It is.

  The seventh gist of the present invention is a pattern forming method comprising a step of applying the resist composition onto a substrate to be processed, a step of exposing with an electron beam, and a step of developing using a developer.

  The polymer of the present invention is highly transparent to light having a wavelength of 250 nm or less, particularly ArF excimer laser light, and is excellent in solubility in an organic solvent. In addition, a resist composition using this is excellent in sensitivity and dry etching resistance, and can be suitably used particularly for lithography using an ArF excimer laser. Moreover, it is possible to manufacture resin suitable for a resist composition by the manufacturing method of this invention.

  According to the pattern forming method of the present invention using such a resist composition, a highly accurate fine resist pattern can be stably formed. This pattern forming method is suitable for deep ultraviolet excimer laser lithography and electron beam lithography, particularly for lithography using an ArF excimer laser.

  The present invention will be described in detail below.

In the present invention, “(meth) acrylic acid” is a general term for acrylic acid and methacrylic acid.

The polymer characterized by containing one or more selected from the structural units represented by the formula (1) of the present invention as a structural unit is represented by the following formula (4):

(In the formula, n, R ^{1 to} R ⁴ , X ¹ , X ² and Y ¹ have the same meanings as in formula (1).)
It can be obtained by polymerizing one or more selected from monomers represented by the formula:

  The monomer represented by the formula (4) may be copolymerized with a monomer other than the monomer represented by the formula (4).

  In the present invention, the monomer is a concept including all geometric isomers, optical isomers and the like, and can be used as a pure isomer or a mixture thereof. Moreover, it can be used even if it contains an intermediate. If necessary, it may be purified by means of ordinary distillation, thin film distillation, recrystallization, column chromatography and the like.

  This polymer is excellent in transparency and solubility in organic solvents, and resist materials formulated with this polymer as a base resin can be used for deep ultraviolet excimer laser lithography without compromising resist performance such as sensitivity, resolution, and dry etching resistance. And is suitable for electron beam lithography.

Examples of C _n H _2n in the formula (1) include a single bond (n = 0), CH ₂ , CH ₂ —CH ₂ , CH ₂ —CH ₂ —CH ₂ , CH (CH ₃ ) —CH _2. Is mentioned. From the viewpoint of dry etching resistance when a polymer is used as a resist composition material, a single bond (n = 0) is preferred.

Examples of the linear or branched alkyl group having 1 to 6 carbon atoms represented by R ² are methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, tert- An amyl group, n-pentyl group, n-hexyl group, etc. are mentioned. From the viewpoint of high substrate adhesion, a methyl group, an ethyl group, and an isopropyl group are preferable, and a methyl group is more preferable.

R ² O can be bonded to any carbon atom in the cyclohexyl ring, but the position represented by the above formulas (2) and (3) is preferable from the viewpoint of high solubility of the polymer in an organic solvent. .

Examples of R ³ and R ^{4 in} the formulas (1) to (2) include a hydrogen atom or a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group. and the like, also in ^{R 3} and _{^{R 4, -CH 2 -, -}} O -, - S -, - NH -, - CH 2 -CH 2 -, - CH 2 -O-CH 2 -, - _{CH 2 -O-C 2 H 4} -, - CH 2 -O-C 3 H 6 -, - CH 2 -O-C 4 H 8 -, - CH 2 -O-C 5 H 10 -, - C 2 H ₄ —O—C ₂ H ₄ —, —C ₂ H ₄ —O—C ₃ H ₆ —, —C ₂ H ₄ —O—C ₄ H ₈ —, —C ₃ H ₆ —O—C ₃ H _6- , —CH ₂ —S—CH ₂ —, —CH ₂ —S—C ₂ H ₄ —, —CH ₂ —S—C ₃ H ₆ —, —CH ₂ —S—C ₄ H ₈ —, — CH _{2 -S-C 5 H 10 -} , - C 2 H 4 -S-C 2 H 4 -, - C 2 H 4 -S-C 3 H 6 -, - C 2 H 4 -S-C 4 H 8 _{-, - C 3 H 6 -S} -C 3 H 6 -, - CH 2 -NH-CH 2 -, - CH 2 -NH-C 2 H 4 -, - CH 2 -NH-C 3 H 6 -, _{-CH 2 -NH-C 4 H 8} -, - CH 2 -NH-C 5 H 10 -, - C 2 H 4 -NH-C 2 H 4 -, - C 2 H 4 -NH-C 3 H 6 _{-, - C 2 H 4 -NH} -C 4 H 8 -, - C 3 H 6 -NH-C 3 H 6 - include structure forming the like. From the viewpoint of the stability and transparency of the polymer, -O- or a methylene chain having 1 to 3 carbon atoms is preferably formed. Stability of the monomer, the dry etching resistance in terms of _-CH 2 in ^{R 3} and _{^{R 4 -, - CH 2 -CH}} 2 - is more preferable to form the, in terms high substrate adhesion, ^{R 3} And R ⁴ more preferably form —O—.

X ¹ and X ² are preferably a direct bond or a methylene chain having 1 to 2 carbon atoms from the viewpoint of high substrate adhesion, and other substituents may be attached to the carbon atom to which X ¹ and X ² are bonded. It is preferable that there is no.

From the viewpoint of the stability of the polymer, a direct bond or —CH ₂ — is more preferable.

Examples of the linear or branched alkyl group having 1 to 6 carbon atoms that X ¹ and X ² may have include the same examples as described above.

Examples of the carboxy group esterified with an alcohol having 1 to 6 carbon atoms that X ¹ and X ² may have include —COOCH ₃ , —COOC ₂ H ₅ , —COOC ₃ H ₇ , and —COOC _4. H ₉ , —COOC ₅ H ₁₀ , —COOC ₆ H ₁₃ (where C ₃ H ₇ is an n-propyl group, iso-propyl group, C ₄ H ₉ is an n-butyl group, sec-butyl group, tert- Butyl group, C ₅ H ₁₀ represents an n-pentyl group, and C ₆ H ₁₃ represents an n-hexyl group).

Examples of the alkoxy group having 1 to 6 carbon atoms that X ¹ and X ² may have include —OCH ₃ , —OC ₂ H ₅ , —OC ₃ H ₇ , —OC ₄ H ₉ , —OC _5. H ₁₀ , —OC ₆ H ₁₃ (where C ₃ H ₇ is n-propyl group, iso-propyl group, C ₄ H ₉ is n-butyl group, sec-butyl group, tert-butyl group, C ₅ H ₁₀ represents an n-pentyl group, and C ₆ H ₁₃ represents an n-hexyl group).

In formulas (1) to (3), a cyclohexyl ring, a linear or branched alkyl group, X ¹ and X ² are not substituted, hydrogen atom, carbon number 1 from the viewpoint of stability and light transmittance of the polymer. It preferably has a -6 linear or branched alkyl group, a hydroxy group, a carboxy group, or a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, adhesion to the substrate, wettability to a developer In view of the above, it is preferable that there is no substituent, or a linear or branched alkyl group having 1 to 3 carbon atoms, a hydroxy group, or a hydroxymethyl group. Or it is more preferable that it has a branched alkyl group.

Y ¹ is preferably O—C (O) or C (O) —O from the viewpoint of high substrate adhesion.

  In summary, the structural unit represented by the formula (1) is preferably the formula (2), and more preferably the formula (3).

Examples of the monomer represented by the formula (4) include monomers represented by the following formulas (6) to (41) and various isomers of these monomers.

(In the formula, R represents hydrogen or a methyl group.)
In addition, a structure in which a hydrogen atom in the above structure is substituted with a hydroxy group, a carboxy group, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an amino group, or a cyano group, etc. Is mentioned.

  Above all, the above formulas (8) to (13), the above formulas (20) to (27), and the above formulas (30) to (30) from the viewpoint of high dry etching resistance and substrate adhesion when a polymer is used for the resist composition. The monomer represented by (35) and various isomers of these monomers are preferable, and the monomer represented by the above formulas (8) to (11), the above formula (30) to (35), and Various isomers of these monomers are more preferable.

  Regarding the ratio of the structural units represented by the above formulas (1) to (3) in the polymer (sum of two or more types), the lower limit is preferably 15 mol% or more in terms of sensitivity and resolution, 30 mol% or more is more preferable. The upper limit is preferably 70 mol% or less, and more preferably 60 mol% or less, in terms of high adhesion to the substrate surface and the like and high solubility in an organic solvent.

The production of the monomer used in the present invention can be carried out in the following steps (Scheme 1 and Scheme 2) as an example, but is not limited thereto.

  Raw materials such as 5-norbornene-2,3-dicarboxylic acid anhydride, 1-cyclohexene-1,2-dicarboxylic acid anhydride and derivatives thereof can be commercially available or synthesized by known production methods.

  A method for obtaining a lactone from an acid anhydride using sodium borohydride as a reducing agent is widely known. Org. Chem. , 35, 3574 (1970) describe a method of synthesizing a lactone compound using sodium borohydride as a reducing agent in THF or DMF solvent, and Synthesis, 42 (1974) describes a method under an ethanol solvent. Describes a method of synthesizing a lactone compound by reduction with sodium borohydride.

  The reaction of oxidizing an unsaturated bond to an epoxy using an organic peroxide such as performic acid or perbenzoic acid is described in “J. Chem. Soc. , 221 (1959).

  As a method for alkylating a hydroxy group into an alkoxy group, various methods such as a method of reacting an alkyl halide in the presence of an alkali are known, and any of them can be used.

  The esterification reaction can be used by any known method. When a carboxylic acid halide such as acrylic acid chloride or methacrylic acid chloride is used, there is a method of adding a base such as triethylamine in a solvent such as methylene chloride.

  In addition, raw materials such as crotonolactone, 5,6-dihydro-2H-pyran-2-one, and derivatives thereof can be commercially available or synthesized by a known production method. The Diels-Alder reaction in which 1,3-butadiene, cyclopentadiene, cyclohexadiene, furan or the like is added to these raw materials proceeds easily by a known method.

  The product of the reaction may contain several structural isomers, geometric isomers, optical isomers. The present invention can be used as an isolated isomer, a mixture of isomers, or an intermediate. If necessary, it may be purified by means such as ordinary distillation, thin film distillation, recrystallization or column chromatography.

  In the present invention, it is preferable to copolymerize a monomer having an acid leaving group in addition to the monomer used in the present invention.

  Here, the “acid leaving group” means a group that decomposes or leaves by the action of an acid.

  When the polymer contains an acid leaving group, the resist composition containing the polymer has excellent sensitivity.

The acid leaving group is not particularly limited as long as it is a group that decomposes or leaves by the action of an acid, but preferably has an alicyclic skeleton from the viewpoint of high dry etching resistance required for a resist. Specifically, the following groups are preferable.

(In the formula, R ²⁴ , R ²⁵¹ and R ²⁵² each independently represent a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms. R ²⁶ and R ²⁷ each independently represent a hydrogen atom or a hetero atom. Represents a monovalent hydrocarbon group which may contain a monovalent hydrocarbon group or a heteroatom, and in this case, examples of the heteroatom include an oxygen atom, a sulfur atom and a nitrogen atom, and —OH , —OR ²⁸ , —O—, —S—, —S (═O) —, —NH ₂ , —NHR ²⁸ , —N (R ²⁸ ) ₂ , —NH—, —NR ²⁸ — and the like R ²⁸ represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms.)
The structural unit having an alicyclic skeleton is a structural unit having a structure having one or more cyclic hydrocarbon groups.

The structural unit having an acid leaving group is represented by the following formula (42-1) or the following formula (42-2) from the viewpoint of high dry etching resistance required for a resist. The structural unit represented by the following formula (42-3) is particularly preferred.

(In formulas (42-1) to (42-3), R represents a hydrogen atom or a methyl group, R ¹ and R ² each independently represents an alkyl group having 1 to 3 carbon atoms, and X represents a substituent. And having at least one group selected from the group consisting of a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an ester group having 1 to 6 carbon atoms and an amino group A linear or branched alkyl group, a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an ester group having 1 to 6 carbon atoms or an amino group, and m is 0 to 4 (In the case where m is 2 or more, X includes a plurality of different groups.)
The “ester group having 1 to 6 carbon atoms” means “carboxy group esterified with an alcohol having 1 to 6 carbon atoms”.

  In formulas (42-1) to (42-3), the position substituted with X may be independently any position of the cyclic structure.

Such a structural unit is usually a group in which a cyclic hydrocarbon group is eliminated by the action of an acid.

R ¹ and R ^{2 in} formulas (42-1) to (42-3) are preferably a methyl group, an ethyl group, or an isopropyl group from the viewpoint of sensitivity and resolution.

  M in the formulas (42-1) to (42-3) is preferably 0 from the viewpoint of high dry etching resistance.

  In order to introduce a structural unit having an acid leaving group into a polymer, a monomer having an acid leaving group may be copolymerized. Monomers having an acid leaving group can be used alone or in combination of two or more as required.

Specific examples of the monomer having an acid leaving group include monomers represented by the following formulas (43-1) to (43-18). In formulas (43-1) to (43-18), R represents a hydrogen atom or a methyl group.

  As the monomer having an acid leaving group, the above formula (43-1), the above formula (43-2), the above formula (43-5), and the above formula (43-5) are particularly preferable in terms of sensitivity and resolution. 43-16) or a monomer represented by the above formula (43-1) and the above formula (43-2) are more preferable. Is particularly preferred.

In addition, examples of the structural unit having an acid leaving group include those shown below.

(In the formula, R ⁸⁰ represents an acid leaving group.)
The polymer of the present invention may further contain structural units other than those described above. That is, the polymer of the present invention may contain a structural unit having a lactone skeleton, a structural unit having a polar group, and other structural units in addition to the above structural units, as appropriate, in combination as necessary. Good.

  In order to introduce a structural unit having a lactone skeleton into the copolymer, for example, copolymerization may be performed using a monomer having a lactone skeleton.

  Examples of the monomer having a lactone skeleton include (meth) acrylic acid derivatives having a δ-valerolactone ring, (meth) acrylic acid derivatives having a γ-butyrolactone ring, and (meth) acrylic acid having an alicyclic lactone. Derivatives and the like, and derivatives having a substituent on the lactone ring of these compounds are exemplified.

Specific examples are shown below.

  Resist copolymers containing structural units having a lactone skeleton have excellent adhesion to highly polar surfaces such as metal surfaces, and excellent sensitivity when these structural units contain acid-eliminable groups. Have Furthermore, when these structural units contain a high carbon density, they have excellent dry etching resistance.

  The ratio of the structural units having a lactone skeleton in the copolymer (excluding the structural units represented by formulas (1) to (3)) is preferably in the range of 1 to 50 mol%, and is preferably 5 to 40 mol%. A range is more preferred.

  In order to improve the pattern shape rectangularity, the polymer of the present invention more preferably includes a structural unit having a polar group.

  In order to introduce a structural unit having a polar group into a polymer, a monomer having a polar group may be copolymerized. The monomer having a polar group having a polar group has at least one of a hydroxyl group, a cyano group, an amino group, and an anhydrous carboxy group, and a monomer having an ethylenic double bond as a polymerizable functional group. It is a mer. Monomers having a polar group can be used alone or in combination of two or more.

  The ratio of the structural unit having a polar group in the copolymer (excluding those containing a lactone skeleton or an acid leaving group) is preferably in the range of 1 to 50 mol%, more preferably in the range of 5 to 40 mol%. preferable.

Examples of the monomer having such a polar group include hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, cyanonorbornyl (meth) acrylate, hydroxyadamantyl (meth) acrylate, ( (Meth) acrylic acid cyanotricyclodecanyl, (meth) acrylic acid hydroxytricyclodecanyl, maleic anhydride, itaconic anhydride, (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) Specific examples of monomers having polar groups include acrylamide and monomers having substituents on the cyclic hydrocarbon groups of these compounds, p-hydroxystyrene, and the like. Monomers represented by 1) to (45-18)

Is mentioned. Among these, the above formulas (45-4) to (45-13) are preferable from the viewpoint of high dry etching resistance. R represents a hydrogen atom or a methyl group.

In addition, as other copolymerizable monomers, for example, the hydrogen atom of the carboxy group of (meth) acrylic acid is methyl, ethyl, 2-ethylhexyl, n-propyl, isopropyl, butyl, isobutyl, t-butyl, adamantyl, methoxymethyl, n-propoxyethyl, i-propoxyethyl, n-butoxyethyl, i-butoxyethyl, t-butoxyethyl, 2-ethoxyethyl, 1-ethoxyethyl, 2,2,2- (Meth) acrylic acid derivatives substituted with functional groups such as trifluoroethyl, 2,2,3,3-tetrafluoro-n-propyl, 2,2,3,3,3-pentafluoro-n-propyl;
The hydrogen atom of the carboxy group of α- (tri) fluoromethylacrylic acid is methyl, ethyl, 2-ethylhexyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, methoxymethyl, ethoxyethyl An α- (tri) fluoromethylacrylic acid derivative having a linear or branched structure, such as n-propoxyethyl, i-propoxyethyl, n-butoxyethyl, i-butoxyethyl, t-butoxyethyl;
Aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyltoluene;
Unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, itaconic acid;
Ethylene, propylene, norbornene, tetrafluoroethylene, vinyl chloride, ethylene, vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, vinylpyrrolidone, etc.
Is mentioned. These monomers can be used singly or in combination of two or more, if necessary, within a range that does not significantly impair the effects of the present invention. Usually, the proportion of structural units derived from these monomers is preferably 20 mol% or less.

  In the polymer of the present invention, when the structural unit having an acid leaving group is contained, the ratio of the structural units represented by the above formulas (1) to (3) is the sum, and the lower limit is 10 mol% or more. Preferably, 20 mol% or more is more preferable. An upper limit is 70 mol% or less, and 60 mol% or less is more preferable. The ratio of the structural units having an acid leaving group is the total, and the lower limit is preferably 30 mol% or more, more preferably 40 mol% or more. An upper limit is 70 mol% or less, and 60 mol% or less is more preferable.

  In the polymer of the present invention, when the structural unit having an acid leaving group and a polar group is contained, the ratio of the structural units represented by the above formulas (1) to (3) is the total, and the lower limit is 10 mol. % Or more, more preferably 20 mol% or more, and the upper limit is preferably 65 mol% or less, more preferably 55 mol% or less. The total ratio of the structural units having an acid leaving group is preferably 30 mol% or more, more preferably 40 mol% or more, and the upper limit is preferably 65 mol% or less, more preferably 60 mol% or less. The total number of structural units having polar groups is preferably 1 mol% or more, more preferably 5 mol% or more, and the upper limit is preferably 30 mol% or less, more preferably 20 mol% or less.

Examples of the polymer of the present invention include the monomer and the following formulas (D) to (K):

And those obtained by copolymerizing one or more selected from the monomers represented by formula (1). In the monomer to be used, an acrylic acid derivative and a methacrylic acid derivative can be used without distinction.

  The above polymers are suitable for resist composition materials, particularly chemically amplified resist composition materials.

  The raw material monomer used in the polymer of the present invention is arbitrarily selected depending on the light source used for lithography.

  For example, when a KrF excimer laser or an electron beam is used as a light source, a polymer obtained by polymerizing the monomer represented by the formula (4) and p-hydroxystyrene or a derivative thereof is preferable in consideration of etching resistance. Used. In this case, the proportion of the structural unit derived from the formula (4) in the polymer is preferably 5 mol% or more, and preferably 60 mol% or less.

  When the polymer of the present invention is used as a chemically amplified resist using an ArF excimer laser as a light source, the polymer containing a structural unit represented by the above formulas (1) to (3) and a structural unit having acid detachability is included. Coalescence is preferred. Such a polymer can improve dry etching resistance without impairing resist performance such as high sensitivity, high resolution, sensitivity, resolution and substrate adhesion, and wettability to a developing solution.

  The mass average molecular weight of the polymer of the present invention is not particularly limited, but the lower limit is preferably 1,000 or more, more preferably 2,000 or more, and further preferably 4,000 or more. The upper limit is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less. If the mass average molecular weight is larger than this, the solubility in the resist solution is lowered and the resolution is lowered. If the mass average molecular weight is smaller than this, the dry etching resistance tends to decrease and the resist shape tends to deteriorate.

  The method for producing the polymer of the present invention is not particularly limited, but a polymerization method called drop polymerization, which is generally performed by solution polymerization and a monomer is dropped into a polymerization vessel, is preferable.

  Among them, from the viewpoint that a polymer having a narrow composition distribution and molecular weight distribution can be easily obtained, a monomer (a monomer alone or a solution obtained by dissolving a monomer in an organic solvent) may be used. It is preferable to produce the polymer of the present invention by a polymerization method called dropping polymerization in which polymerization is performed while dropping in a polymerization vessel.

  In the dropping polymerization method, for example, an organic solvent is previously charged in a polymerization vessel, heated to a predetermined polymerization temperature, and then a monomer, a polymerization initiator, and a chain transfer agent dissolved in an organic solvent as required. The body solution is dropped into the organic solvent in the polymerization vessel. The monomer may be dropped without being dissolved in the organic solvent. In that case, a solution in which the polymerization initiator and, if necessary, the chain transfer agent are dissolved in the monomer is dropped into the organic solvent. Further, the monomer may be dropped into the polymerization vessel without previously charging the organic solvent into the polymerization vessel. Moreover, a monomer, a polymerization initiator, and a chain transfer agent can each be dripped individually or in arbitrary combinations. The polymerization temperature in the dropping polymerization method is not particularly limited, but is preferably in the range of 50 to 150 ° C.

  Although it does not specifically limit as an organic solvent used for manufacture of the polymer of this invention, When using a monomer, a polymerization initiator, the obtained polymer, and also a chain transfer agent, all the chain transfer agents can be dissolved. A solvent is preferable, and examples thereof include 1,4-dioxane, isopropyl alcohol, acetone, tetrahydrofuran (hereinafter also referred to as “THF”), ethyl lactate, and the like. In addition, the usage-amount of an organic solvent is not specifically limited, What is necessary is just to determine suitably.

  The polymerization initiator used in the production of the polymer of the present invention is not particularly limited. For example, azobisisobutyronitrile (hereinafter also referred to as AIBN), 2,2′-azobis (2,4-dimethylvaleronitrile) ) And other organic peroxides such as benzoyl peroxide. Further, mercaptans such as n-butyl mercaptan, n-octyl mercaptan and 2-mercaptoethanol may be used as a chain transfer agent. In addition, the usage-amount of a polymerization initiator and a chain transfer agent is not specifically limited, What is necessary is just to determine suitably.

  Next, an example of a method for using the resist copolymer of the present invention will be described.

  The resist copolymer solution produced by a method such as solution polymerization is used as it is or 1,4-dioxane, acetone, THF, methyl isobutyl ketone, γ-butyrolactone, propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMEA). In some cases, after diluting to a suitable solution viscosity with a good solvent such as ethyl lactate, the solution is dropped into a large amount of poor solvent such as methanol or water to precipitate a resist copolymer. This step is generally called “reprecipitation” and may be unnecessary in some cases, but is very effective for removing unreacted monomers remaining in the polymerization solution, polymerization initiators, and the like. If these unreacted substances remain as they are, there is a possibility of adversely affecting the resist performance. Therefore, it is preferable to remove them as much as possible.

  Then, the resist copolymer of the present invention can be obtained by filtering the precipitate and drying it sufficiently. Moreover, after filtering off, it can also be used with a moist powder without drying. Further, the produced copolymer solution can be used as a resist composition as it is or after being diluted with an appropriate solvent. At that time, additives such as a storage stabilizer may be appropriately added.

  The resist composition of the present invention is obtained by dissolving the resist polymer of the present invention as described above in a solvent. The chemically amplified resist composition of the present invention is obtained by dissolving the resist polymer of the present invention and a photoacid generator as described above in a solvent. The resist polymer of the present invention may be used alone or in combination of two or more. In addition, without separating the polymer from the polymer solution obtained by solution polymerization or the like, this polymer solution can be used as it is in the resist composition, or the polymer solution can be diluted with an appropriate solvent to form a resist. It can also be used in a composition.

  The lower limit of the content of the polymer of the present invention in the resist composition of the present invention is preferably 1% by mass or more and more preferably 5% by mass or more in terms of excellent resist performance. Moreover, an upper limit is a point with low viscosity, 80 mass% or less is preferable and 50 mass% or less is more preferable.

  When the resist composition of the present invention is used for a chemically amplified resist, it is necessary to use a photoacid generator. Here, the photoacid generator is a compound that generates an acid upon irradiation with actinic rays or radiation. A photo-acid generator may use 1 type or may use 2 or more types together.

  Examples of such a photoacid generator include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, quinonediazide compounds, diazomethane compounds, and the like. Among them, it is preferable to use an onium salt compound such as a sulfonium salt, an iodonium salt, a phosphonium salt, a diazonium salt, or a pyridinium salt. Specifically, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, (hydroxyphenyl) benzylmethylsulfonium toluenesulfonate, diphenyliodonium triflate, diphenyliodonium pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate And diphenyliodonium hexafluoroantimonate.

The content of the photoacid generator is appropriately determined depending on the type of the photoacid generator used and the like, but is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the polymer of the present invention, 0.5 More preferably, it is at least part by mass. By setting the content of the photoacid generator within this range, a chemical reaction due to the catalytic action of the acid generated by exposure can be sufficiently caused. Moreover, it is preferable that it is 20 mass parts or less with respect to 100 mass parts of polymers of this invention, and, as for content of a photo-acid generator, it is more preferable that it is 10 mass parts or less. By setting the content of the photoacid generator within this range, the stability of the resist composition is improved, and the occurrence of uneven coating during application of the composition and scum during development is reduced. One or more photoacid generators are selected as necessary.

  The solvent used in the resist composition of the present invention is arbitrarily selected according to the purpose, but the choice of the solvent is limited due to reasons other than the solubility of the resin, such as uniformity of the coating film, appearance, or safety. I may receive it.

  Solvents usually used in the present invention include linear ketones such as methyl ethyl ketone, 2-pentanone and 2-hexanone, cyclic ketones such as cyclopentanone and cyclohexanone, propylene glycol monoalkyl acetates such as PGMEA, ethylene Ethylene glycol monoalkyl ether acetates such as glycol monomethyl ether acetate, propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, diethylene glycol alkyl ethers such as diethylene glycol dimethyl ether, Esters such as ethyl acetate and ethyl lactate, n-propyl alcohol, isopropyl alcohol, n- Chiruaruko - le, tert- butyl alcohol - le, cyclohexanol, alcohols such as 1-octanol, 1,4-dioxane, ethylene carbonate, .gamma.-butyrolactone. These solvents may be used alone or in combination of two or more.

  The amount of the solvent used is usually 200 parts by mass or more and more preferably 300 parts by mass or more with respect to 100 parts by mass of the resist polymer (the polymer of the present invention). Moreover, the usage-amount of a solvent is 5000 mass parts or less normally with respect to 100 mass parts of resist polymers (polymer of this invention), and it is more preferable that it is 2000 mass parts or less.

  Furthermore, various additives such as surfactants, quenchers, sensitizers, antihalation agents, storage stabilizers, antifoaming agents, and the like can be blended with the resist composition of the present invention as necessary. Any of these additives can be used as long as it is known in the art. Moreover, the compounding quantity of these additives is not specifically limited, What is necessary is just to determine suitably.

  Next, an example of the pattern forming method of the present invention will be described.

  First, the chemically amplified resist composition of the present invention is applied to the surface of a substrate to be processed such as a silicon wafer on which a pattern is formed by spin coating or the like. Then, the substrate to be processed coated with the chemically amplified resist composition is dried by baking (pre-baking) or the like, and a resist film is formed on the substrate to be processed.

  Next, the resist film thus obtained is irradiated with light or an electron beam having a wavelength of 250 nm or less through a photomask (exposure). The light used for exposure is preferably a KrF excimer laser or an ArF excimer laser, and particularly preferably an ArF excimer laser.

  After light irradiation (exposure), baking treatment (PEB) is appropriately performed, the substrate is immersed in an alkaline developer, and the exposed portion is dissolved and removed in the developer (development). Any known alkaline developer may be used. Then, after development, the substrate is appropriately rinsed with pure water or the like. In this way, a resist pattern is formed on the substrate to be processed.

  Usually, a substrate to be processed on which a resist pattern is formed is appropriately baked (post-baked) to strengthen the resist and selectively etch a portion without the resist. After etching, the resist is usually removed using a release agent.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these description. Here, “part” in each example and comparative example means “part by mass” unless otherwise specified.

  The physical properties of the polymer and the resist were evaluated by the following methods.

<Mass average molecular weight (Mw), dispersity (Mw / Mn)>
It calculated | required in polystyrene conversion with the gel permeation chromatography (henceforth GPC). As the solvent, chloroform or THF was used.

<Average copolymer composition (mol%)>
^It calculated | required by the measurement of < ¹ > H-NMR and < ¹³ > C-NMR. As the solvent, deuterated chloroform or deuterated dimethyl sulfoxide was used.

<Solubility in resist solvent>
Each polymer was dissolved in a predetermined amount of resist solvent (PGMEA) with stirring at room temperature so that the solid content concentration was 20% by mass, and the time until complete dissolution was measured. The results are shown in Tables 2 and 3.

  The meanings of the symbols in the table are as follows.

◎: Time until the polymer is completely dissolved is less than 1 hour ○: Time until the polymer is completely dissolved is 1 hour or more and less than 6 hours Δ: Time until the polymer is completely dissolved is 6 hours Or more and less than 24 hours x: time until the polymer is completely dissolved is 24 hours or more, or insoluble <Preparation of Resist Composition and Resist Film>
100 parts of a copolymer, 2 parts of triphenylsulfonium triflate, 630 parts of PGMEA, and 70 parts of γ-butyrolactone were mixed to form a uniform solution, and then filtered using a Teflon (registered trademark) filter to obtain a resist composition solution. Prepared. A resist composition solution was spin-coated on a silicon wafer and pre-baked at 120 ° C. for 60 seconds using a hot plate to form a thin film having a thickness of 400 nm. <Sensitivity>
The resulting resist film was exposed using a 193 nm light irradiation apparatus (SP193 manufactured by Nikon), and immediately post-exposure baked at 120 ° C. for 60 seconds. Subsequently, it was developed for 60 seconds at room temperature using a 2.38 mass% aqueous tetramethylammonium hydroxide solution, washed with pure water and dried.

  Sensitivity was defined as the minimum exposure amount at which the resist film was completely dissolved and the silicon wafer surface was exposed.

<Etching rate>
A silicon wafer coated with a resist film having a thickness of 400 nm was subjected to a dry etching process using an SPE-220T type dry etching apparatus manufactured by Showa Vacuum Co., Ltd. The gas was a CF ₄ / O ₂ mixed gas, and the treatment time was 2 minutes. The film thickness of the resist film before and after the dry etching process was measured using a Lambda Ace VM-8000J type optical interference type film thickness measuring device manufactured by Dainippon Screen Mfg. Co., Ltd. The etching rate was used. The etching rate was normalized with the novolac resin etching rate set to 1.

  The smaller the etching rate, the better the dry etching resistance.

[Synthesis Example 1] Synthesis of polymer P-1 represented by the following formula (46)

A separable flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer was charged with 24.0 parts of ethyl lactate under a nitrogen atmosphere, and the temperature of the hot water bath was raised to 70 ° C. while stirring. 14.0 parts of the mixture of the formulas (8 ′) and (9 ′), 11.0 parts of 2-methacryloyloxy-2-methyladamantane (hereinafter referred to as MAdMA), 24.0 parts of THF, and 0.98 parts of AIBN The mixed monomer solution was dropped into the flask at a constant rate over 6 hours, and then kept at 70 ° C. for 2 hours. Next, the obtained reaction solution was added dropwise to 800 parts of methanol with stirring to obtain a white precipitate. The precipitate was filtered off and dried under reduced pressure at 60 ° C. for about 10 hours. The precipitate was dissolved in 45 parts of THF and added dropwise to 800 parts of methanol while stirring. The resulting precipitate was filtered off and dried at 60 ° C. under reduced pressure for about 40 hours.

When each physical property was measured, the mass average molecular weight (hereinafter referred to as Mw) by GPC analysis was 12400, the dispersity (hereinafter referred to as Mw / Mn) was 1.68, and the copolymerization ratio was an integral ratio of ¹ H-NMR. To a mixture of the above formulas (8 ′) and (9 ′): MAdMA = 50: 50.

ＭＡｄＭＡ：２−メタクリロイルオキシ−２−メチルアダマンタン

ＥＡｄＭＡ：２−メタクリロイルオキシ−２−エチルアダマンタン

ＩＡｄＭＡ：１−メタクリロイルオキシイソプロピルアダマンタン

ＨＡｄＭＡ：１−メタクリロイルオキシ−３−ヒドロキシアダマンタン

ＯＴＤＭＡ：８−または９−メタクリロイルオキシ−４−オキサトリシクロ[５.２.１.０^２,６]デカン−３−オン
[実施例１〜７、比較例１〜２]
合成例１〜９でそれぞれ得られた重合体Ｐ−１〜Ｐ−９を用いて調製したレジスト組成物の感度およびエッチング速度を測定して表３に示した。

[Synthesis Examples 2-9] (Synthesis of Polymers P-2 to P-9)
Polymers P-2 to P-9 were obtained in the same manner as in Synthesis Example 1. Table 2 shows the average copolymer composition, mass average molecular weight Mw, and degree of dispersion Mw / Mn of the obtained polymer.

MAdMA: 2-methacryloyloxy-2-methyladamantane

EAdMA: 2-methacryloyloxy-2-ethyladamantane

IAdMA: 1-methacryloyloxyisopropyl adamantane

HAdMA: 1-methacryloyloxy-3-hydroxyadamantane

OTDMA: 8- or 9-methacryloyloxy-4-oxatricyclo [5.2.1.0 ^2,6 ] decan-3-one
[Examples 1-7, Comparative Examples 1-2]
The sensitivity and the etching rate of the resist compositions prepared using the polymers P-1 to P-9 obtained in Synthesis Examples 1 to 9, respectively, were measured and shown in Table 3.

  As described above, the chemically amplified resist composition using the polymer of the present invention has sufficient sensitivity and excellent dry etching resistance, and also has excellent solubility in an organic solvent.

Claims (11)

Following formula (1)

(In the formula (1), n represents an integer of 0 to 3, R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear or branched alkyl group having 1 to 6 carbon atoms, R ³ , R ⁴ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, or an alkylene chain having 1 to 6 carbon atoms represented by R ³ and R ⁴ , —O—, —S—, or — NH ¹ is formed, X ¹ and X ² represent a direct bond or an alkylene chain having 1 to 3 carbon atoms, and Y ¹ represents an oxygen atom, C (O), O—C (O) or C (O) —O. In addition, the cyclohexyl ring, the alkyl group, the alkylene group, X ¹ and X ² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, and 1 to 6 carbon atoms. Carboxyl group, amino group, cyano esterified with alcohol It may have.)
The polymer containing the structural unit represented by these. Following formula (2)

(In the formula ^(2), R 1 ~R ^{4 is, X 1, X 2, Y} 1 is as defined for formula (1) ^.R 5 ~R ⁸ each independently represent a hydrogen atom and a A linear or branched alkyl group, a hydroxy group, a carboxy group, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, an amino group or a cyano group, and the linear or branched alkyl having 1 to 6 carbon atoms. The group may have a hydroxy group, a carboxy group, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an amino group, or a cyano group.)
The polymer containing the structural unit represented by these. Following formula (3)

(In the formula ^{(3), R 1, X} 1, X 2, Y 1 is as defined for formula ^(1), R 5 ~R ⁸ are as defined in the formula (2) .Z is 1 to carbon atoms 3 methylene chains or oxygen atoms.)
The polymer containing the structural unit represented by these.



  Furthermore, the polymer in any one of Claims 1-3 containing the structural unit which has an acid leaving group.   The polymer according to any one of claims 1 to 4, which has a mass average molecular weight of 1,000 to 100,000.   The method for producing a polymer according to any one of claims 1 to 5, wherein the polymerization is performed while dropping the monomer into the polymerization vessel.   A resist composition comprising the polymer according to claim 1.   The resist composition according to claim 7, further comprising a photoacid generator.   A pattern forming method comprising: a step of applying the resist composition according to claim 7 on a substrate to be processed; a step of exposing with light having a wavelength of 250 nm or less; and a step of developing using a developer. .   The pattern forming method according to claim 9, wherein the light used for exposure is an ArF excimer laser.   A pattern forming method comprising a step of applying the resist composition according to claim 7 or 8 onto a substrate to be processed, a step of exposing with an electron beam, and a step of developing using a developer.