JP2010191221A - Chemically amplified photoresist composition for exposure to extreme-ultraviolet ray - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoresist composition having high sensitivity in exposure to extreme-UV rays. <P>SOLUTION: The chemically amplified photoresist composition for exposure to extreme-UV rays contains a polymer compound having a repeating unit expressed by formula (I) as a structural unit, and a photoacid generator. In the formula (I), R<SP>1</SP>represents a hydrogen atom, a methyl group, or the like; R<SP>2</SP>, R<SP>3</SP>and R<SP>4</SP>each may be a hydrogen atom, a 1-6C straight-chain alkyl group, a 3-6C branched alkyl group or a 3-6C cyclic alkyl group; and A and B each represents an oxygen atom or a sulfur atom. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a chemically amplified photoresist composition for extreme ultraviolet (EUV) exposure.

In recent years, in the field of electronic device manufacturing typified by integrated circuit element manufacturing, there has been an increasing demand for higher integration of devices, and therefore, a photolithography technique for forming a fine pattern is required.
As a next-generation technology corresponding to a half pitch of 22 nm or more, a lithography technology using extreme ultraviolet [Extreme Ultra Violet (hereinafter abbreviated as EUV)] having a wavelength of 13.5 nm is the most promising and can be used for it. There is a need for photoresists with sensitivity and high resolution. Regarding the photoresist performance, there is a strong demand for improving the sensitivity, particularly from the viewpoint of maintaining the resolution of a fine pattern and increasing the productivity.

By the way, it is said that most of acid generation in EUV exposure is not via direct excitation of the photoacid generator but via ionization of the resist polymer. For this reason, it is considered that the molecular structure of the monomer and the polymer composition contribute greatly to the acid generation efficiency and sensitivity (Non-patent Document 1).
In recent years, it has been reported that the acid generation efficiency and sensitivity of the photoresist composition in EUV exposure have been improved by introducing halogen atoms into the resist polymer. (See Non-Patent Documents 2 and 3.) On the other hand, it has also been reported that the acid generation amount and sensitivity are improved when the hydroxy group content in the resist polymer is increased (see Non-Patent Documents 4 and 5).

“Proceeding SPIE”, vol. 3999, p. 204 (2000) “Journal of Vacuum Science and Technology”, vol. B23, p. 2728 (2005) “Proceeding SPIE”, vol. 6923, p. 471 (2008) “Japan Journal of Applied Physics”, vol. 45, no. 9A, p. 6866 (2006) “Applied Physics Express”, vol. 1, p. 067001 (2008)

However, it is also known that when EUV hits a halogen atom-containing polymer as disclosed in Non-Patent Documents 2 and 3, some of the carbon-halogen bonds are broken and hydrogen halide is generated. The generation of such hydrogen halide contributes to improving the resist sensitivity, but is not suitable for industrial implementation because it causes contamination of the optical system in the exposure apparatus and corrosion in the chamber. Further, as disclosed in Non-Patent Documents 4 and 5, when the content of hydroxy groups in the polymer is large, the hydrophilicity of the whole polymer is increased, and the resist pattern may swell.
Accordingly, an object of the present invention is to provide a highly sensitive photoresist composition for EUV exposure that solves the above-mentioned problems.

  That is, the present invention provides [1] the following general formula (I)

(Wherein R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group.
The combination of R ² , R ³ and R ⁴ is
1) R ² , R ³ and R ⁴ are each independently a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclic group having 3 to 6 carbon atoms. Represents an alkyl group. ;
2) R ² and R ³ are linked to each other to represent an alkylene group having 3 to 6 carbon atoms, and R ⁴ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 3 to 6 carbon atoms. Represents a group or a cyclic alkyl group having 3 to 6 carbon atoms. Or 3) R ² represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, and R ³ and R ⁴ represents an alkylene group having 3 to 6 carbon atoms by linking. One of them.
R ⁵ and R ⁸ each independently represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.
Each of R ⁶ and R ⁷ independently represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms; Or R ⁶ and R ⁷ are linked to each other to represent an alkylene group having 3 to 6 carbon atoms.
A and B each independently represent an oxygen atom or a sulfur atom. )
A chemically amplified photoresist composition for extreme ultraviolet exposure, comprising a polymer compound having a repeating unit represented by the following structural units, a photoacid generator and a solvent:
[2] The following general formula (1-1)

(In the formula, R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group. A and B each independently represent an oxygen atom or a sulfur atom.)
A chemically amplified photoresist composition for extreme ultraviolet exposure, comprising a polymer compound having a repeating unit represented by the following structural units, a photoacid generator and a solvent:
[3] The chemically amplified photoresist composition for extreme ultraviolet exposure according to the above [1] or [2], wherein the photoacid generator is an onium salt,
[4] The chemically amplified photoresist composition for extreme ultraviolet exposure according to [3] above, wherein the onium salt is a fluorine-containing onium salt, and [5] any one of [1] to [4] above. Forming a resist film on a substrate using a chemically amplified photoresist composition for extreme ultraviolet exposure, and exposing the resist film to extreme ultraviolet light, followed by alkali development,
Is achieved by providing

  The chemically amplified photoresist composition obtained by the present invention is suitable for EUV exposure. By using the chemically amplified photoresist composition to form a resist pattern using EUV exposure, a finer resist pattern can be formed with higher productivity than in the past.

[Chemically amplified photoresist composition for EUV exposure]
The chemically amplified photoresist composition for EUV exposure of the present invention (hereinafter simply referred to as a photoresist composition) comprises (1) a polymer compound, (2) a photoacid generator and (3) a solvent, and Accordingly, (4) a basic compound, (5) a surfactant, and (6) other additives are contained.

((1) polymer compound)
As the polymer compound, the solubility in an alkali developer is changed by reaction with an acid, and the repeating unit represented by the following general formula (I) [hereinafter referred to as repeating unit (I)]. ] Is contained.

In the repeating unit (I), R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group.
The combination of R ² , R ³ and R ⁴ is
1) R ² , R ³ and R ⁴ are each independently a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclic group having 3 to 6 carbon atoms. Represents an alkyl group. ;
2) R ² and R ³ are linked to each other to represent an alkylene group having 3 to 6 carbon atoms, and R ⁴ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 3 to 6 carbon atoms. Represents a group or a cyclic alkyl group having 3 to 6 carbon atoms. Or 3) R ² represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, and R ³ and R ⁴ represents an alkylene group having 3 to 6 carbon atoms by linking. One of them.
Examples of the linear alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group. Examples of the branched alkyl group having 3 to 6 carbon atoms include an isopropyl group, an isobutyl group, and a sec-butyl group. Examples of the cyclic alkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.
Examples of the alkylene group having 3 to 6 carbon atoms when R ² and R ³ are connected include, for example, a propane-1,3-diyl group, a butane-1,4-diyl group, and a pentane-1,5-diyl group. And hexane-1,6-diyl group. Among these, a butane-1,4-diyl group is preferable.
Examples of the alkylene group having 3 to 6 carbon atoms when R ³ and R ⁴ are linked include, for example, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5- Examples thereof include a diyl group and a hexane-1,6-diyl group.
The combination of R ^2, R ³ and R ⁴ are, from the viewpoint of acid generation efficiency and sensitivity in the EUV exposure is preferably from above 1), R ^2, R ³ and R ⁴ are each a hydrogen atom or a methyl group More preferably, both are hydrogen atoms.

In the repeating unit (I), R ⁵ and R ⁸ are each independently a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, or 3 to 6 carbon atoms. Represents a cyclic alkyl group.
Each of R ⁶ and R ⁷ independently represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms; Or R ⁶ and R ⁷ are linked to each other to represent an alkylene group having 3 to 6 carbon atoms.
Examples of the linear alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group. Examples of the branched alkyl group having 3 to 6 carbon atoms include an isopropyl group, an isobutyl group, and a sec-butyl group. Examples of the cyclic alkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.
Examples of the alkylene group having 3 to 6 carbon atoms in which R ⁶ and R ⁷ are linked include a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, and hexane. And a -1,6-diyl group. Among these, a butane-1,4-diyl group is preferable.
R ⁵ , R ⁶ , R ⁷ and R ⁸ are all preferably hydrogen atoms from the viewpoint of acid generation efficiency and sensitivity in EUV exposure.
In the repeating unit (I), A and B each independently represent an oxygen atom or a sulfur atom.

The ratio of the repeating unit (I) to the total repeating units in the polymer compound is more than 0 mol% and 100 mol%, preferably 10 to 80 mol%, more preferably 20 to 70 mol%.
Specific examples of the repeating unit (I) include the following formulas (2-1) to (2-20) [wherein A and B are as defined above. p represents 1 or 2. However, it is not particularly limited to these.

  The polymer compound used in the present invention is a homopolymer of a monomer (hereinafter referred to as monomer (II)) that generates repeating unit (I), or monomer (II) and another polymerizable compound. [Hereinafter referred to as polymerizable compound (III). ] Is obtained by copolymerization.

(Monomer (II))
Specific examples of the monomer (II) include acrylic acid ester derivatives represented by the following formulas (3-1) to (3-20) [wherein A, B and p are as defined above. However, it is not particularly limited to this.

(Method for producing monomer (II))
The monomer (II) can be produced, for example, by the method shown in the chemical reaction formula below.

In the above chemical reaction formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , A and B are as defined above. R ⁹ and R ¹⁰ each independently represents a linear alkyl group having 1 to 3 carbon atoms or a branched alkyl group having 3 to 6 carbon atoms. X represents a chlorine atom, a bromine atom or an iodine atom.
Hereinafter, although the manufacturing method of monomer (II) shown to the said chemical-reaction formula is demonstrated, it does not specifically limit to this.

The acrylic acid ester can be produced by using the acetal (III) and the heteroalcohol (IV) as raw materials and going through the following first to third steps.
(First step)
The first step is a step of producing hydroxyacetal (V) by reacting acetal (III) and heteroalcohol (IV) in the presence of a base.

Acetal (III) is commercially available or can be produced by subjecting the corresponding α-haloketone compound or α-haloaldehyde to a conventional acetalization reaction.
As acetal (III), chloroacetaldehyde = dimethyl = acetal, chloroacetaldehyde = diethyl = acetal, bromoacetaldehyde = dimethyl = acetal, bromoacetaldehyde = diethyl = acetal, 1-bromo-2,2-dimethoxypropane, 1-iodo- 2,2-diethoxypropane, 2-bromo-3,3-diethoxybutane, 1-chloro-2,2-dimethoxyhexane, 1-chloro-2,2-dimethoxyheptane, 1-chloro-2,2- Examples include dimethoxycyclopentane, 1-chloro-2,2-dimethoxycyclohexane, 1-bromo-2,2-dimethoxycycloheptane and the like.

  Examples of the heteroalcohol (IV) include 3-mercapto-1-butanol, 2-methyl-3-mercapto-1-propanol, 4-mercapto-2-butanol, 3-methyl-3-mercapto-1-butanol, 2,2-dimethyl-3-mercapto-1-propanol, 2-isopropyl-2-methyl-3-mercapto-1-propanol, 2-methyl-4-mercapto-2-butanol, 2-ethyl-2-methyl- 3-mercapto-1-propanol, 1-mercapto-3-pentanol, 2-ethyl-3-mercapto-1-propanol, 3-mercapto-1-propanol, 4-mercapto-1-butanol, 5-mercapto-2 -Pentanol, 2-methyl-5-mercapto-2-pentanol, 4-mercapto-1-pentano 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2, 2-diethyl-1,3-propanediol, 1,3-butanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,4-dimethyl-2,4-pentanediol, 2 2,4-trimethyl-1,3-pentanediol, 1,4-butanediol, 1,4-pentanediol, 2,5-dimethyl-2,5-hexanediol and the like.

  Among the heteroalcohols (IV), those in which B represents a sulfur atom are commercially available, or a method of reacting a corresponding halogenated alcohol with sodium hydrosulfide or potassium hydrosulfide, and corresponding halogenation It can be produced by a method of reducing alcohol after reacting with benzyl sulfide. Among the heteroalcohols (IV), those in which B represents an oxygen atom are commercially available, or the corresponding dihalide or halogenated alcohol is substituted with a hydroxyl group using silver nitrate and water. It can be produced by reducing the corresponding diketone compound or diester compound.

  Examples of the base used in the first step include inorganic bases such as sodium hydride, sodium hydroxide, and sodium carbonate; alcohol salts such as sodium methylate; triethylamine, N, N-dimethylaniline, pyridine, diazabicyclo [2. 2.2] Organic bases such as octane. It is preferable that the usage-amount of a basic substance is the range of 0.8-5 mol with respect to 1 mol of heteroalcohol (IV) from a viewpoint of economical efficiency and a post-process.

  The first step can be carried out without a solvent or by adding a solvent. As the solvent used, for example, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as toluene; halogenated hydrocarbons such as methylene chloride; alcohols such as methanol; ethers such as tetrahydrofuran can be preferably used. It is also possible to use acetal (III) or heteroalcohol (IV) as a solvent / reactant.

In general, the reaction temperature in the first step is preferably in the range of 0 to 100 ° C.
The pressure in the first step is not particularly limited, but normal pressure is preferable from the viewpoint of ease of operation.
The target hydroxyacetal (V) produced in the first step can be separated and purified by, for example, filtering off the salt produced by the reaction after completion of the reaction, concentrating the filtrate obtained, and distilling it.

(Second step)
The second step is a step of hydrolyzing and cyclizing the hydroxyacetal (V) obtained in the first step in the presence of an acid catalyst.
Examples of the acid catalyst used in the second step include carboxylic acids such as acetic acid; sulfonic acids such as p-toluenesulfonic acid; and mineral acids such as hydrochloric acid. It is preferable that the usage-amount of an acid catalyst is the range of 0.0001-1 times mole with respect to a hydroxyacetal (V) from a viewpoint of economical efficiency and the ease of post-processing.

  The water used in the second step is not particularly limited as long as it is not less than the required theoretical amount (1 mol per mol of hydroxyacetal (V)), but in order to produce the desired cyclic alcohol (VI) advantageously. It is preferable to use a large excess with respect to the hydroxyacetal (V), and from the viewpoint of economy and ease of post-treatment, it is preferably in the range of 1 to 10,000 times the molar amount relative to the hydroxyacetal (V).

The second step can be carried out without a solvent or by adding a solvent. As the solvent used, for example, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as toluene; halogenated hydrocarbons such as methylene chloride; ethers such as tetrahydrofuran can be preferably used. It is also possible to use water as a solvent and reactant.
When using a solvent, it is preferable that the usage-amount is the range of 0.1-10 mass times with respect to a hydroxyacetal (V) from a viewpoint of economical efficiency and the ease of post-processing.

In general, the reaction temperature in the second step is preferably in the range of 0 to 100 ° C.
The pressure in the second step can be carried out at normal pressure or under reduced pressure.
The reaction in the second step can be stopped by neutralizing the acid catalyst. Examples of the neutralizing agent include sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, triethylamine, pyridine and the like.

  Separation and purification of the cyclic alcohol (VI) from the reaction mixture obtained in the second step may be performed by appropriately combining ordinary organic chemical operations such as solvent extraction, distillation, column chromatography, and recrystallization.

(Third step)
In the third step, the cyclic alcohol (VI) produced in the second step is represented by the general formula CH ₂ = CR ¹ COX ^{1 in} the presence of a basic substance (wherein R ¹ is as defined above. X ¹ is (Represents a chlorine atom, a bromine atom or an iodine atom).
Specific examples of the polymerizable group introducing agent represented by the general formula CH ₂ = CR ¹ COX ¹ include acrylic acid chloride, methacrylic acid chloride, 2-trifluoromethylacrylic acid chloride and the like.
It is preferable that the usage-amount of a polymeric group introduction | transduction agent is the range of 0.8-5 mol with respect to 1 mol of cyclic alcohol (VI) from a viewpoint of economical efficiency and the ease of post-processing.

  Examples of the basic substance used in the third step include inorganic bases such as sodium hydride, sodium hydroxide, and sodium carbonate; organic bases such as triethylamine, pyridine, and diazabicyclo [2.2.2] octane. It is preferable that the usage-amount of a basic substance is the range of 0.8-5 mol with respect to 1 mol of cyclic alcohol (VI) from a viewpoint of economical efficiency and a post-process.

The third step can be performed in the presence or absence of a solvent. Examples of the solvent include ethers such as tetrahydrofuran; aliphatic hydrocarbons such as hexane; halogenated hydrocarbons such as methylene chloride; aromatic hydrocarbons such as toluene; amides such as N, N-dimethylformamide; dimethyl sulfoxide and the like. It is done.
When using a solvent, there is no restriction | limiting in particular in the usage-amount, However, Usually, it is preferable that it is the range of 0.1-20 mass parts with respect to 1 mass part of cyclic alcohol (VI).
It is preferable to implement 3rd process in the range of -80-100 degreeC. The reaction time is usually in the range of 10 minutes to 10 hours.

  The third step can be stopped by adding water and / or alcohol. Examples of such alcohol include methanol, ethanol, n-propanol, i-propanol and the like. The amount of water and / or alcohol used may be 1 mol or more per 1 mol of the polymerizable group-introducing agent relative to the cyclic alcohol (VI).

The monomer (II) thus obtained is preferably separated and purified by a conventional method as necessary. For example, the reaction mixture can be washed with water, concentrated, and purified by a method used for separation and purification of ordinary organic compounds such as distillation, column chromatography, or recrystallization.
In addition, if necessary, metal with nitrilotriacetic acid, ethylenediaminetetraacetic acid, etc., or with Zeta Plus (trade name: Cuno Co., Ltd.) or Protego (product name: Nihon Microlith Co., Ltd.) It is also possible to reduce the metal content in the obtained monomer (II) by the removal filter treatment.

(Polymerizable compound (III))
Specific examples of the polymerizable compound (III) that can be copolymerized with the monomer (II) include compounds (4-1) to (4-10) represented by the following chemical formulas. However, it is not particularly limited to these.

In the above formula, R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ¹² represents a polymerizable group. R ¹³ represents a hydrogen atom or —COOR ¹⁴ , and R ¹⁴ represents an alkyl group having 1 to 3 carbon atoms. R ¹⁵ represents an alkyl group. R ¹⁶ represents a hydrogen atom or —COOR ¹⁷ , and R ¹⁷ represents an alkyl group or a cycloalkyl group.
Examples of the alkyl group having 1 to 3 carbon atoms independently represented by R ¹¹ and R ¹⁴ include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Examples of the alkyl group independently represented by R ¹⁵ and R ¹⁷ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, and a t-butyl group. Examples thereof include an alkyl group having 1 to 8 carbon atoms. Examples of the cycloalkyl group represented by R ¹⁷ include a cyclopentyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a cyclooctyl group, and an adamantyl group. Examples of the polymerizable group represented by R ¹² include an acryloyl group, a methacryloyl group, a vinyl group, and a crotonoyl group.
R ¹¹ is preferably a hydrogen atom, a methyl group, an ethyl group, or an isopropyl group. R ¹² is preferably an acryloyl group or a methacryloyl group. R ¹³ is preferably a hydrogen atom. R ¹⁵ is preferably an alkyl group having 1 to 8 carbon atoms. The R ^16, preferably -COOR ^17, examples of the R ^17, preferably an alkyl group having 1 to 8 carbon atoms.
The polymerizable compound (III) that can be copolymerized with the monomer (II) is preferably the compound (4-2).

((1) Production method of polymer compound)
The aforementioned polymer compound can be produced by radical polymerization according to a conventional method. In particular, examples of the method for synthesizing a polymer having a small molecular weight distribution include living radical polymerization. A general radical polymerization method includes one or more types of monomers (II) and, if necessary, one or more types of polymerizable compounds (III), a radical polymerization initiator and a solvent, and, if necessary, In the presence of a chain transfer agent.
Hereinafter, this radical polymerization method will be described.

The method for carrying out radical polymerization is not particularly limited, and conventional methods such as those used in the production of acrylic polymer compounds such as solution polymerization, emulsion polymerization, suspension polymerization and bulk polymerization can be used.
Examples of the radical polymerization initiator include hydroperoxide compounds such as t-butyl hydroperoxide and cumene hydroperoxide; dialkyl such as di-t-butyl peroxide, t-butyl-α-cumyl peroxide and di-α-cumyl peroxide. Peroxide compounds; diacyl peroxide compounds such as benzoyl peroxide and diisobutyryl peroxide; and azo compounds such as 2,2′-azobisisobutyronitrile and dimethyl-2,2′-azobisisobutyrate.
The amount of radical polymerization initiator used can be appropriately selected according to the polymerization conditions such as the monomer (II), polymerizable compound (III), chain transfer agent, solvent used in the polymerization reaction; Is the total polymerizable compound [the total of the monomer (II) and the polymerizable compound (III), and so on. ] It is usually in the range of 0.005 to 0.2 mol and preferably in the range of 0.01 to 0.15 mol with respect to 1 mol.

  Examples of the chain transfer agent include thiol compounds such as dodecanethiol, mercaptoethanol, mercaptopropanol, mercaptoacetic acid, and mercaptopropionic acid. You may use these individually by 1 type or in mixture of 2 or more types. When a chain transfer agent is used, the amount used is usually in the range of 0.005 to 0.2 mol and in the range of 0.01 to 0.15 mol with respect to 1 mol of the total polymerizable compound. Is preferred.

The radical polymerization is usually carried out in the presence of a solvent. The solvent is not particularly limited as long as the polymerization reaction is not inhibited. For example, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether propionate, ethylene glycol Glycol ethers such as monobutyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether; esters such as ethyl lactate, methyl 3-methoxypropionate, methyl acetate, ethyl acetate, propyl acetate; acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, Methyl amyl ketone, cyclopentanone, cyclohexanone What ketone diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, ethers such as 1,4-dioxane. You may use a solvent individually by 1 type or in mixture of 2 or more types.
The usage-amount of a solvent is the range of 0.5-20 mass parts normally with respect to 1 mass part of all the polymeric compounds, and it is preferable that it is the range of 1-10 mass parts from a viewpoint of economical efficiency. .

The reaction temperature for radical polymerization is usually preferably 40 to 150 ° C., more preferably 60 to 120 ° C. from the viewpoint of the stability of the polymer compound produced.
The reaction time for radical polymerization varies depending on the monomer (II), polymerizable compound (III), polymerization initiator, type and amount of solvent used, and polymerization conditions such as reaction temperature, but is usually from 30 minutes to 48 hours. It is preferable that it is the range of 1 hour-24 hours, and it is more preferable.

The polymer compound thus obtained can be isolated by ordinary operations such as reprecipitation.
Examples of the solvent used in the reprecipitation operation include aliphatic hydrocarbons such as pentane and hexane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene and xylene; methylene chloride, chloroform, chlorobenzene, and dichlorobenzene. Nitrogenated hydrocarbons such as nitromethane; Nitriles such as acetonitrile and benzonitrile; Ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran and 1,4-dioxane; Ketones such as acetone and methyl ethyl ketone; Acetic acid and the like Carboxylic acid; Esters such as ethyl acetate and butyl acetate; Carbonates such as dimethyl carbonate, diethyl carbonate, and ethylene carbonate; Methanol, ethanol, propanol, isopropyl alcohol Le, alcohols such as butanol; and water. You may use these individually by 1 type or in mixture of 2 or more types.
The amount of the solvent used varies depending on the type of polymer compound and the type of solvent, but it is usually preferably in the range of 0.5 to 100 parts by mass with respect to 1 part by mass of the polymer compound, from the viewpoint of economy. Is more preferably in the range of 1 to 50 parts by mass.
The polymer compound isolated in this way can also be dried by vacuum drying or the like.

Specific examples of the polymer compound shown above include those represented by the following chemical structural formulas (5-1) to (5-168) and (6-1) to (6-175) (in the chemical structural formula) , R ¹⁸ to R ⁵⁰ each independently represent a hydrogen atom or a methyl group, and a, b, c, d, and e represent the molar ratio of each repeating unit, and a + b = 1, c + d + e = 1), but is not particularly limited thereto.

  Although there is no restriction | limiting in particular in the weight average molecular weight (Mw) of the high molecular compound used by this invention, Preferably it is the range of 500-50000, More preferably, it is the range of 1000-30000 of the photoresist composition of this invention. Highly useful as an ingredient. In addition, the measuring method of a weight average molecular weight (Mw) is as the description in an Example.

((2) Photoacid generator)
As the photoacid generator to be contained in the photoresist composition of the present invention, a known photoacid generator usually used in a conventional chemically amplified resist can be used. Examples of the photoacid generator include onium salt photoacid generators such as iodonium salts and sulfonium salts; oxime sulfonate photoacid generators; bisalkyl or bisarylsulfonyldiazomethane photoacid generators; nitrobenzyl sulfonate photoacids Examples include generators; iminosulfonate photoacid generators; disulfone photoacid generators. You may use these individually by 1 type or in mixture of 2 or more types. Among these, an onium salt photoacid generator is preferable, and the following fluorine-containing onium salt containing a fluorine-containing alkyl sulfonate ion as an anion is preferable from the viewpoint that the strength of the generated acid is strong.

  Specific examples of the fluorine-containing onium salt include, for example, diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate; bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate; triphenylsulfonium trifluoromethane. Sulfonate, heptafluoropropane sulphonate or nonafluorobutane sulphonate; tri (4-methylphenyl) sulphonium trifluoromethane sulphonate, heptafluoropropane sulphonate or nonafluorobutane sulphonate; dimethyl (4-hydroxynaphthyl) sulphonium trifluoromethane sulphonate, heptafluoro Propanesulfonate or nonafluorobuta Sulfonate; Triphenylmethane sulfonate, heptafluoropropane sulfonate or nonafluorobutane sulfonate of monophenyldimethylsulfonium; Trifluoromethane sulfonate, heptafluoropropane sulfonate or nonafluorobutane sulfonate of diphenylmonomethylsulfonium; Trifluoro of (4-methylphenyl) diphenylsulfonium L-methanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate; (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate; tri (4-tert-butyl) phenylsulfonium trifluoromethanes Honeto and heptafluoropropane sulfonate or nonafluorobutane sulfonates. You may use these individually by 1 type or in mixture of 2 or more types.

  The content of the photoacid generator is usually preferably in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of the polymer compound from the viewpoint of ensuring the sensitivity and developability of the photoresist composition. More preferably, it is in the range of 0.5 to 10 parts by mass.

((3) Solvent)
Examples of the solvent contained in the photoresist composition of the present invention include propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether propionate, and ethylene glycol monobutyl ether. Glycol ethers such as ethylene glycol monobutyl ether acetate and diethylene glycol dimethyl ether; esters such as ethyl lactate, methyl 3-methoxypropionate, methyl acetate, ethyl acetate, propyl acetate; acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl Ketone, cyclopentanone, cyclohexanone What ketone diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, ethers such as 1,4-dioxane. You may use these individually by 1 type or in mixture of 2 or more types.
The content of the solvent is usually in the range of 1 to 50 parts by mass and preferably in the range of 2 to 25 parts by mass with respect to 1 part by mass of the polymer compound.

((4) Basic compound)
Furthermore, in order to improve the resolution by suppressing the diffusion rate of acid in the photoresist film, the photoresist composition of the present invention has a basic compound as a characteristic of the photoresist composition of the present invention. A range of uninhibited amounts can be included.
Examples of such basic compounds include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N- (1-adamantyl) acetamide, benzamide, N-acetyl. Ethanolamine, 1-acetyl-3-methylpiperidine, pyrrolidone, N-methylpyrrolidone, ε-caprolactam, δ-valerolactam, 2-pyrrolidinone, acrylamide, methacrylamide, t-butylacrylamide, methylenebisacrylamide, methylenebismethacrylamide Amides such as N-methylolacrylamide, N-methoxyacrylamide and diacetoneacrylamide; pyridine, 2-methylpyridine, 4-methylpyridine, nicotine, quinoline, Lysine, imidazole, 4-methylimidazole, benzimidazole, pyrazine, pyrazole, pyrrolidine, piperidine, tetrazole, morpholine, 4-methylmorpholine, piperazine, 1,4-diazabicyclo [2.2.2] octane, tributylamine, tripentyl Examples include amines such as amine, trihexylamine, triheptylamine, trioctylamine, and triethanolamine. You may use these individually by 1 type or in mixture of 2 or more types.
When the basic compound is contained, the content thereof varies depending on the type of the basic compound, but it is usually preferably in the range of 0.01 to 10 mol per mol of the photoacid generator. The range of 05 to 1 mol is more preferable.

((5) Surfactant)
In order to improve the coating property, the photoresist composition of the present invention may further contain a surfactant in an amount that does not impair the properties of the photoresist composition of the present invention.
Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, and the like. You may use these individually by 1 type or in mixture of 2 or more types.
When the surfactant is contained, the content thereof is usually 2 parts by mass or less with respect to 100 parts by mass of the polymer compound.

((6) Other additives)
Further, the photoresist composition of the present invention has other properties such as a sensitizer, an antihalation agent, a shape improver, a storage stabilizer, an antifoaming agent, and the like. A range of uninhibited amounts can be included.

[Method of forming resist pattern]
A desired resist pattern can be formed by forming a resist film on a substrate using the photoresist composition of the present invention, exposing the resist film to EUV, and then performing alkali development.
First, a photoresist composition is applied to a substrate and prebaked to form a resist film on the substrate. As temperature at the time of prebaking, 70-160 degreeC is preferable, 80-150 degreeC is more preferable, and 100-140 degreeC is further more preferable. Although the heating time at the time of pre-baking changes with temperature, 1 minute-10 minutes are preferable normally and 1 minute-5 minutes are more preferable.
The resist film obtained by pre-baking is exposed through a desired mask. At this time, EUV having a wavelength of 10 to 15 nm (preferably 13.5 nm) is used. The photoresist composition of the present invention is highly sensitive to the EUV and has high acid generation efficiency.
After irradiation (exposure) with EUV, post-exposure baking is performed to form a latent image pattern. As temperature at the time of post-exposure baking, 70-160 degreeC is preferable, 80-150 degreeC is more preferable, 100-140 degreeC is further more preferable. Although the heating time at the time of post-exposure baking varies depending on the temperature, it is usually preferably 1 minute to 10 minutes, more preferably 1 minute to 5 minutes.
Next, a desired resist pattern can be formed by alkali development using the following developer. Examples of the developer include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate and aqueous ammonia; alkylamines such as ethylamine, diethylamine and triethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; tetramethylammonium hydroxy And an alkaline aqueous solution in which a quaternary ammonium salt such as tetraethylammonium hydroxide is dissolved. Among these, an alkaline aqueous solution in which a quaternary ammonium salt is dissolved is preferable, and an alkaline aqueous solution in which tetramethylammonium hydroxide and tetraethylammonium hydroxide are dissolved is more preferable.
Usually, the alkali concentration in the developer is preferably in the range of 0.1 to 20% by mass, and more preferably in the range of 0.1 to 10% by mass.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited at all by this Example. In addition, the measuring method of Mw and Mn in each example and the calculation method of dispersion degree are as follows.

(Measurement of Mw and Mn and calculation of dispersity)
The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) using a differential refractometer as a detector and tetrahydrofuran (THF) as an eluent under the following conditions. It calculated | required as a conversion value by the calibration curve created with the standard polystyrene. Further, the dispersity (Mw / Mn) was determined by dividing the weight average molecular weight (Mn) by the number average molecular weight (Mn).
GPC measurement: TSK-gel SUPER HZM-H (trade name: 4.6 mm × 150 mm) and TSK-gel SUPER HZ2000 (trade name: Tosoh Corp., 4.6 mm × 150 mm) as columns ) Using one connected in series, measurement was performed under the conditions of a column temperature of 40 ° C., a differential refractometer temperature of 40 ° C., and an eluent flow rate of 0.35 mL / min.

<Synthesis Example 1-1> Production of 1,4-oxathian-2-ol

(First step)
691 g of methanol was placed in a 2 L four-necked flask equipped with a thermometer, a reflux condenser, and a stirrer. The flask was cooled in an ice bath, and 128.1 g (3.20 mol) of sodium hydroxide was added little by little with stirring so that the temperature did not exceed 50 ° C. Stirring was continued after the addition of sodium hydroxide was completed, and when the temperature reached 2 to 5 ° C, 250.3 g (3.20 mol) of mercaptoethanol was brought into the range of 5 to 10 ° C from the dropping funnel. Was slowly added dropwise.
After completion of the dropwise addition, stirring was continued for 1 hour, and 295.6 g (2.37 mol) of chloroacetaldehyde = dimethyl = acetal was dropped from the dropping funnel so that the temperature was in the range of 5 to 10 ° C. Heating was started after completion | finish of dripping, and it stirred for 14 hours in temperature within the range of 70-75 degreeC. At this time, when analyzed by gas chromatography, the conversion of chloroacetaldehyde = dimethyl = acetal was 95.5%.
After the temperature of the reaction solution was lowered to room temperature, the reaction solution was filtered to remove the generated salt, and the filtrate was concentrated under reduced pressure and subjected to simple distillation. (2-hydroxyethylthio) acetaldehyde = dimethyl = acetal 334.0 g (1.89 mol) having the following physical properties under the conditions of pressure 545 Pa, kettle temperature 146 ° C. and distillation temperature 122 ° C. as a pale yellow transparent liquid Obtained (purity 94.3%, yield 80%).

¹ H-NMR (300 MHz, CDCl ₃ , TMS, ppm) δ: 2.60-2.67 (1H, br), 2.71 (2H, d, J = 5.4 Hz), 2.77 (2H, t, J = 5.8 Hz), 3.37 (6H, s), 3.73 (2H, dt, J = 5.7, 5.8 Hz), 4.48 (1H, t, J = 5.4 Hz) )

(Second step)
Next, 672.3 g of water, (2-hydroxyethylthio) acetaldehyde = dimethyl = acetal 100.0 g (565 mmol) and 5.0 were added to a 1 L four-necked flask equipped with a thermometer, a distillation head and a stirrer. 1.67 g of a mass% sulfuric acid aqueous solution was added. The mixture was stirred for 4 hours while distilling off water and generated methanol under the conditions of a pressure of 16.0 kPa and an internal temperature of 70 ° C. At this time, when analyzed by gas chromatography, the conversion rate of (2-hydroxyethylthio) acetaldehyde = dimethyl = acetal was 94.2%.
After the temperature in the kettle was lowered to room temperature, the pH was adjusted to 8.0 with a 4.0 mass% aqueous sodium hydroxide solution, and extraction was performed three times with 400 g of ethyl acetate. The obtained three extractions were combined and concentrated under reduced pressure to obtain 63.3 g of a concentrate. The concentrate was dissolved in 158 g of diisopropyl ether at 50 ° C., slowly cooled to 8 ° C., and the precipitated white crystals were filtered off to obtain 35.1 g (287 mol) of 1,4-oxathian-2-ol as white. Obtained as crystals (purity 98.2%, yield 51%).

<Synthesis Example 1-2> Production of 1,4-oxathian-2-yl methacrylate

(Third step)
To a 2 L four-necked flask equipped with a thermometer, a dropping funnel and a stirrer, 431 g of THF, 42.9 g (351 mmol) of 1,4-oxathian-2-ol obtained in Synthesis Example 1-1, and 0.61 g of phenothiazine were obtained. And the inside of the flask was purged with nitrogen. With the flask cooled in an ice bath, 71.1 g (703 mmol) of triethylamine was added dropwise from the dropping funnel so that the temperature was in the range of 2 to 5 ° C. Next, 51.3 g (486 mmol) of methacrylic acid chloride was added dropwise so that the temperature was in the range of 5 to 10 ° C. After completion of the dropwise addition, stirring was continued at 3 to 6 ° C. for 1.5 hours. At this time, when analyzed by gas chromatography, the conversion of 1,4-oxathian-2-ol was 99.9%.
From the dropping funnel, 290 g of water was slowly dropped so that the temperature was less than 20 ° C., and the ice bath was removed and the internal temperature was adjusted to 24 ° C. after the dropping. 4-dimethylaminopyridine (3.0 g) was added and stirred at 24-26 ° C for 3 hours. At this time, when analyzed by gas chromatography, the ratio of methacrylic anhydride to 1,4-oxathian-2-yl methacrylate was methacrylic anhydride: 1,4-dithian-2-yl methacrylate = 0. 3: 99.7 (area ratio).
The mixture was transferred to a 2 L separatory funnel and extracted three times with 285 g of ethyl acetate. Three times of the obtained extract was put into a separatory funnel having a content volume of 2 L, and washed with 285 g of a 1% aqueous hydrochloric acid solution three times and 285 g of water. 0.017 g of p-methoxyphenol and 0.017 g of phenothiazine were added, and the solvent was distilled off under reduced pressure to obtain 82.4 g of a distilled stock solution. For distillation, a molecular distillation apparatus “MS-300” (manufactured by SHIBATA) was used. The high-boiling fraction obtained by flowing the distillation stock solution at a pressure of 13.3 to 26.6 Pa and a temperature of 30 to 35 ° C. is flowed at a pressure of 9.3 to 13.3 Pa and a temperature of 40 to 45 ° C. As a result, 54.4 g (285 mmol) of 1,4-oxathian-2-yl methacrylate having the following physical properties was obtained as a colorless and transparent liquid (purity 98.7%, yield 81%).

¹ H-NMR (300 MHz, CDCl ₃ , TMS, ppm) δ: 1.97 (3H, s), 2.58-2.2.63 (2H, m), 2.73 (1H, dd, J = 6.0, 13.4 Hz), 2.83 (1H, dd, J = 2.4, 13.4 Hz), 3.97 (1 H, m), 4.29 (1 H, m), 5.66 ( 1H, m), 5.98 (1H, ddd = 1.1, 2.4, 6.0 Hz), 6.23 (1H, s)

<Synthesis Example 2-1> Production of 1,4-dioxan-2-ol

(First step)
350.0 g (5.64 mol) of 1,2-ethanediol was placed in a four-necked flask having an internal volume of 1 L equipped with a thermometer, a reflux condenser, and a stirrer. The flask was cooled in an ice bath, and 237.0 g (4.23 mol) of potassium hydroxide was added little by little with stirring so that the temperature did not exceed 50 ° C. After the addition of potassium hydroxide was completed, 351.2 g (2.82 mol) of chloroacetaldehyde = dimethyl = acetal was added dropwise so that the temperature was in the range of 40 to 50 ° C. Heating was started after completion | finish of dripping, and it stirred for 22 hours in the range whose temperature is 110-112 degreeC. At this time, when analyzed by gas chromatography, the conversion of chloroacetaldehyde = dimethyl = acetal was 78.6%.
After the temperature of the reaction solution was lowered to room temperature, the reaction solution was filtered to remove the generated salt, and the filtrate was simply distilled. Under the conditions of a pressure of 533 to 933 Pa, an internal temperature of 105 to 119 ° C., and a distillation temperature of 96 to 102 ° C., 315.6 g of a transparent liquid was obtained. When this liquid was analyzed by gas chromatography, the purity of 2- (2,2-dimethoxyethyloxy) ethanol was 50.0%. Next, the obtained liquid was distilled using a distillation column with McMahon as a filler. 101.8 g of 2- (2,2-dimethoxyethyloxy) ethanol was obtained as a colorless and transparent liquid under the conditions of a pressure of 133 to 493 Pa, an internal temperature of 113 to 137 ° C., and a distillation temperature of 82.5 to 87.0 ° C. (Purity 97.5%, yield 23.5% based on chloroacetaldehyde = dimethyl = acetal).
(Second step)
Next, in a four-necked flask having an internal volume of 200 mL equipped with a thermometer, a distillation head and a stirrer, 137.4 g of water, 42.2 mg of sulfuric acid and 20.0 g (130 mmol) of 2- (2,2-dimethoxyethyloxy) ethanol were added. ) The mixture was stirred for 11 hours while distilling off water and methanol produced under the conditions of a pressure of 18.0 kPa and an internal temperature of 60 ° C. At this time, when analyzed by gas chromatography, the conversion of 2- (2,2-dimethoxyethyloxy) ethanol was 99.6%.
After the temperature in the kettle was lowered to room temperature, the pH was adjusted to 8.3 with 10.0 mass% aqueous sodium hydroxide solution, and the mixture was extracted 3 times with 300 g of ethyl acetate. The obtained three extractions were combined and concentrated under reduced pressure, and 17.41 g of the resulting concentrate was simply evaporated. Under the conditions of a pressure of 1.60 kPa, a kettle temperature of 97 to 115 ° C., and a distillation temperature of 92 to 96 ° C., 8.50 g of 1,4-dioxan-2-ol was obtained as a colorless transparent liquid (purity 92.5% Yield 58.1% based on 2- (2,2-dimethoxyethyloxy) ethanol).

<Synthesis Example 2-2> Production of 1,4-dioxan-2-yl methacrylate

(Third step)
A four-necked flask with an internal volume of 50 mL equipped with a thermometer and a stirrer was purged with nitrogen, and then 10.23 g of THF and 3.00 g (26.7 mmol) of 1,4-dioxane-2-ol obtained in Synthesis Example 2-1. , 53 mg of phenothiazine, 5.56 g (54.9 mmol) of triethylamine and 0.23 g (1.87 mmol) of 4- (dimethylamino) pyridine were successively added. Next, 4.01 g (38.4 mmol) of methacrylic acid chloride was added dropwise so that the temperature was in the range of 3 to 5 ° C. After completion of dropping, stirring was continued at 4 to 10 ° C. for 4 hours. At this time, when analyzed by gas chromatography, the conversion of 1,4-dioxane-2-ol was 99.9%. 20 g of water was slowly added dropwise so that the temperature was less than 10 ° C. After the addition, the ice bath was removed and the internal temperature was set to 22 ° C., followed by stirring for 1 hour. At this time, when analyzed by gas chromatography, the ratio of methacrylic anhydride to 1,4-dioxane-2-yl methacrylate was methacrylic anhydride: 1,4-dioxane-2-yl methacrylate = 0. 1: 99.9 (area ratio).
The mixture was transferred to a separatory funnel having a content of 100 mL and extracted three times with 20 g of ethyl acetate. Three times of the obtained extract was put into a separatory funnel having an internal volume of 100 mL and washed successively with 20% of 2% hydrochloric acid aqueous solution, 20 g of 1% sodium hydroxide aqueous solution, 20 g of 5% sodium hydrogen carbonate aqueous solution and 10 g of saturated brine. did. By purifying the concentrate obtained by distilling off the solvent by silica gel column chromatography (developing solvent is n-hexane: ethyl acetate = 8: 1 (volume ratio)), 1,4 having the following physical properties -Dioxane-2-yl methacrylate 4.10g (23.6mmol) was obtained as a colorless and transparent liquid (purity 99.1%, yield 88.5%).

¹ H-NMR (300 MHz, CDCl ₃ , TMS, ppm) δ: 1.98 (3H, s), 3.65 (1H, dt, J = 11.7, 2.7 Hz), 3.74-3. 87 (m, 4H), 4.07-4.21 (m, 1H), 5.65-5.68 (m, 1H), 5.91 (1H, t, J = 2.0 Hz), 6. 25 (s, 1H)

<Synthesis Example 3-1> Synthesis of 1,4-dithian-2-ol

(First step)
1390 g of 1,2-dimethoxyethane was placed in a 3 L four-necked flask equipped with a thermometer, a dropping funnel and a stirrer, and the atmosphere in the flask was replaced with nitrogen. While cooling the flask in a water bath, 79.0 g (1.96 mol) of sodium hydride (60%) was added and stirred for 30 minutes. After attaching a reflux condenser, 181.2 g (1.92 mol) of 1,2-ethanedithiol was slowly added dropwise from the dropping funnel so that the temperature was in the range of 25 to 30 ° C. At this time, gas generation was observed. After stirring for about 30 minutes from the end of dropping, 154.3 g (0.96 mol) of 2-chloro-1-methoxyethyl = acetate obtained in Synthesis Example 1-1 from the dropping funnel was adjusted to a temperature in the range of 25 to 30 ° C. The solution was slowly dripped into. After completion of the dropwise addition, stirring was continued at 25 to 35 ° C. for 3 hours. When analyzed by gas chromatography at this time, the conversion of 2-chloro-1-methoxyethyl acetate was 99.2%.
(Second step)
906.5 g of water was slowly dropped from the dropping funnel at a temperature in the range of 25 to 60 ° C., and after the dropping, the water bath was heated and the temperature was kept at 60 ° C. for 12 hours. At this time, when analyzed by gas chromatography, the ratio of 1,4-dithian-2-ol to 1,4-dithian-2-yl acetate is 1,4-dithian-2-ol: 1,4-dithiane- 2-yl = acetate = 85: 15 (area ratio).
From the dropping funnel, a 10% aqueous hydrochloric acid solution was added dropwise at a temperature in the range of 10 to 15 ° C. to adjust the pH to 8.1 (drop amount 112.6 g). The obtained liquid was transferred to a separatory funnel having an internal volume of 5 L, and extracted twice with 1670 g of diisopropyl ether. Two portions of the extract thus obtained were put into a separatory funnel having an internal volume of 5 L, washed successively with 801 g of water and 504 g of saturated brine, and the solvent was distilled off under reduced pressure to obtain 285.9 g of concentrate. The obtained concentrate was charged with 47.5 g of diisopropyl ether, 85.2 g of n-hexane and a small amount of crystal seeds, and slowly cooled to 0 ° C. The precipitate was collected by filtration, transferred to a 300 mL eggplant flask, added with 320 g of n-hexane, and stirred at 25 ° C. for 1 hour. The precipitate was filtered again and dried at room temperature under reduced pressure to obtain 73.8 g (0.52 mol) of 1,4-dithian-2-ol having the following physical properties as a white solid (purity 94). 0.1%, yield 53%).

¹ H-NMR (300 MHz, CDCl ₃ , TMS, ppm) δ: 2.52-2.62 (3H, m), 2.85 (1H, dd, J = 2.1, 13.4 Hz); 52-3.64 (1H, br), 3.86 (1H, ddd, J = 5.0, 5.2, 12.1 Hz), 4.28 (1H, ddd, J = 4.8, 4. 9, 12.1 Hz), 5.03 (1H, ddd, J = 1.9, 5.8, 7.7 Hz)

<Synthesis Example 3-2> Synthesis of 1,4-dithian-2-yl methacrylate

(Third step)
To a 4-liter flask having an internal volume of 1 L equipped with a thermometer, a dropping funnel and a stirrer, 34.5 g (238 mmol) of 1,4-dithian-2-ol obtained in Synthesis Example 1-2, 349.3 g of THF, phenothiazine 0 .47 g was added and the atmosphere in the flask was replaced with nitrogen. With the flask cooled in an ice bath, 48.2 g (476 mmol) of triethylamine was added dropwise from the dropping funnel so that the temperature was in the range of 5 to 8 ° C.
Next, 30.4 g (287.9 g) of methacrylic acid chloride was added dropwise so that the temperature was in the range of 5 to 10 ° C. After completion of the dropwise addition, stirring was continued at 3 to 6 ° C. for 2.5 hours. At this time, when analyzed by gas chromatography, the conversion of 1,4-dithian-2-ol was 99.6%.
From the dropping funnel, 233 g of water was slowly added dropwise so that the temperature was less than 20 ° C., and after the addition, the ice bath was removed and the internal temperature was adjusted to 24 ° C. 1.46 g of 4-dimethylaminopyridine was added and stirred at 24-26 ° C. for 2 hours. At this time, when analyzed by gas chromatography, the ratio of methacrylic anhydride to 1,4-dithian-2-yl methacrylate is methacrylic anhydride: 1,4-dithian-2-yl methacrylate = 0. 1: 99.9 (area ratio).
The obtained liquid was transferred to a separatory funnel having an internal volume of 2 L and extracted three times with 240 g of ethyl acetate. Three times of the obtained extract was put into a separatory funnel having a content volume of 2 L, washed with 230 g of 1% aqueous hydrochloric acid solution three times, 116 g of water, 118 g of saturated aqueous sodium hydrogen carbonate solution, twice with 118 g of water, and washed successively with 100 g of saturated brine. did. 0.010 g of p-methoxyphenol and 0.020 g of phenothiazine were added, and the solvent was distilled off under reduced pressure to obtain 55.0 g of a distilled stock solution. For distillation, a molecular distillation apparatus “MS-300” (manufactured by SHIBATA) was used. The distillation stock solution was allowed to flow at a pressure of 13.3 to 20.0 Pa and a temperature of 40 to 45 ° C. to obtain 47.4 g of a high-boiling fraction. The high-boiling fraction was allowed to flow at a pressure of 10.7 to 13.3 Pa and a temperature of 55 to 60 ° C., and 37.8 g of 1,4-dithian-2-yl methacrylate showing the following physical properties in the low-boiling fraction. 182 mmol) was obtained as a colorless and transparent liquid (purity 98.4%, yield 76%).

¹ H-NMR (300 MHz, CDCl ₃ , TMS, ppm) δ: 2.00 (3H, s), 2.68-2.82 (2H, m), 2.94 (1H, dd, J = 5. 2, 14.1 Hz), 3.10 (1 H, ddd, J = 2.2, 13.2 Hz), 3.30-3.41 (2 H, m), 5.67 (1 H, s), 5. 87-5.92 (1H, m), 6.28 (1H, s)

<Synthesis Example 4> Synthesis of Polymer Compound a In a 300 ml round bottom flask equipped with an electromagnetic stirrer, a reflux condenser and a thermometer, 1,4-oxathian-2-yl methacrylate 8 was added in a nitrogen atmosphere. .48 g (42.5 mmol), 3-hydroxy-1-adamantyl methacrylate 10.05 g (42.5 mmol), 1,4-dioxane 150.2 g and 2,2′-azobis (2,4-dimethylvaleronitrile) ) 1.96 g (7.90 mmol) was charged, and a polymerization reaction was performed at 60 to 62 ° C. for 6 hours.
The obtained reaction mixture was dropped into diisopropyl ether having a mass of about 20 times the reaction mixture at room temperature while stirring, and the produced precipitate was collected by filtration.
A solution obtained by dissolving the precipitate in 150.0 g of THF was dropped into a diisopropyl ether / methanol mixed solution (mass ratio diisopropyl ether: methanol = 4: 1) having the same mass as above while stirring, and the generated precipitate was collected by filtration. Then, a white precipitate was obtained by washing with a diisopropyl ether / methanol mixed solution having the same mass as above (mass ratio diisopropyl ether: methanol = 4: 1).
The precipitate was dried at 50 ° C. under reduced pressure (26.7 Pa) for 10 hours to obtain 11.3 g of a polymer compound a consisting of the following repeating units. The obtained polymer compound a had an Mw of 17,700 and a dispersity of 1.95.

<Synthesis Example 5> Synthesis of polymer compound b In Synthesis Example 4, 1,4-dioxan-2-yl methacrylate was used instead of 8.48 g (42.5 mmol) of 1,4-oxathian-2-yl methacrylate. The polymerization reaction was carried out under the same charge and conditions as in Synthesis Example 4 except that 7.32 g (42.5 mmol) of lato was used.
The obtained reaction mixture was dropped into diisopropyl ether having a mass of about 10 times the reaction mixture at room temperature while stirring, and the resulting precipitate was collected by filtration.
A solution obtained by dissolving the precipitate in 150.0 g of THF was dropped into a diisopropyl ether / methanol mixed solution (mass ratio diisopropyl ether: methanol = 4: 1) having the same mass as above while stirring, and the generated precipitate was collected by filtration. Then, a white precipitate was obtained by washing with a diisopropyl ether / methanol mixed solution having the same mass as above (mass ratio diisopropyl ether: methanol = 4: 1).
The precipitate was dried at 50 ° C. under reduced pressure (26.7 Pa) for 10 hours to obtain 10.3 g of a polymer compound b consisting of the following repeating units. Mw of the obtained polymer compound b was 10400, and the degree of dispersion was 1.93.

<Synthesis Example 6> Synthesis of polymer compound c In Synthesis Example 4, 1,4-dithian-2-yl methacrylate was used instead of 8.48 g (42.5 mmol) of 1,4-oxathian-2-yl methacrylate. The polymerization reaction was carried out under the same charging amount and conditions as in Synthesis Example 4 except that 8.67 g (42.5 mmol) of lath was used.
The obtained reaction mixture was dropped into diisopropyl ether having a mass of about 10 times the reaction mixture at room temperature while stirring, and the resulting precipitate was collected by filtration.
A solution obtained by dissolving the precipitate in 150.0 g of THF was dropped into a diisopropyl ether / methanol mixed solution (mass ratio diisopropyl ether: methanol = 4: 1) having the same mass as above while stirring, and the generated precipitate was collected by filtration. Then, a white precipitate was obtained by washing with a diisopropyl ether / methanol mixed solution having the same mass as above (mass ratio diisopropyl ether: methanol = 4: 1).
The precipitate was dried at 50 ° C. under reduced pressure (26.7 Pa) for 10 hours to obtain 11.1 g of a polymer compound c consisting of the following repeating units. The obtained polymer compound c had an Mw of 13700 and a dispersity of 1.50.

<Synthesis Example 7> Synthesis of Polymer Compound d 10.0 g of 2-methyl-2-adamantyl methacrylate was added to a 200 ml round bottom flask equipped with an electromagnetic stirrer, a reflux condenser and a thermometer under a nitrogen atmosphere. (42.3 mmol), 3-hydroxy-1-adamantyl methacrylate 10.0 g (42.7 mmol), propylene glycol monomethyl ether 80.0 g and 2,2′-azobisisobutyronitrile 1.40 g (8. 53 mmol), and a polymerization reaction was carried out at 81 to 87 ° C. for 2 hours.
The obtained reaction mixture was added dropwise with stirring to about 20 times the mass of methanol at room temperature with stirring, and the resulting precipitate was collected by filtration. A solution obtained by dissolving the precipitate in 100.0 g of THF was dropped into methanol of the same mass as above while stirring, and the resulting precipitate was collected by filtration and washed with methanol of the same mass as above to obtain a white precipitate. Obtained.
The precipitate was dried at 50 ° C. under reduced pressure (26.7 Pa) for 10 hours to obtain 13.2 g of a polymer compound d having the following repeating units. The obtained polymer compound d had an Mw of 16,100 and a dispersity of 1.68.

<Examples 1-3 and Comparative Example 1> Sensitivity measurement under EUV exposure 100 parts by mass of the polymer compound a, b, c or d obtained in Synthesis Examples 4-7 and TPS- as a photoacid generator 109 parts (product name, component; triphenylsulfonium nonafluoro-n-butanesulfonate, manufactured by Midori Chemical Co., Ltd.) and a mixed solvent of propylene glycol monomethyl ether acetate / cyclohexanone = 1/1 (mass ratio) Photoresist compositions A to D having a polymer compound concentration of 5 mass% were prepared.
Each of the obtained photoresist compositions was filtered using a filter [made of tetrafluoroethylene resin (PTFE), pore size: 0.2 μm]. Each of the filtrates was applied onto a silicon wafer having a diameter of 10 cm by spin coating, and pre-baked on a hot plate at 130 ° C. for 90 seconds to form a resist film having a thickness of about 100 nm.
The obtained resist film was subjected to EUV (wavelength 13.5) by using an EUV exposure apparatus (see “Japanes Journal of Applied Physics”, vol. 44, p. 5556 (2005)) installed at the University of Hyogo Newsbar Synchrotron Radiation Facility BL3. 5 nm) was irradiated (exposure). The exposure time is measured by measuring the exposure energy per unit time (0.026 mJ / cm ² · S) with a photoelectric plate installed in the apparatus before exposure to the resist film, and converting it to the desired exposure energy. Were determined.
After the exposure, the film was post-exposure baked at 130 ° C. for 90 seconds, and then developed with an aqueous 2.38 mass% tetramethylammonium hydroxide solution for 60 seconds.
The resist film thickness of the exposed part after development processing was measured. This operation was performed several times while changing the exposure energy, and a sensitivity curve was prepared for each photoresist composition. Sensitivity (E ₀ ) was determined from the obtained sensitivity curve. The results are shown in Table 1.

  From Table 1, it was confirmed that the photoresist composition of the present invention has higher EUV exposure sensitivity than the conventional photoresist composition.

  The photoresist composition obtained by the present invention is particularly suitable for EUV exposure, and can perform fine pattern formation required in the field of electronic device production with higher productivity than in the past.

Claims (5)

The following general formula (I)

(Wherein R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group.
The combination of R ² , R ³ and R ⁴ is
1) R ² , R ³ and R ⁴ are each independently a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclic group having 3 to 6 carbon atoms. Represents an alkyl group. ;
2) R ² and R ³ are linked to each other to represent an alkylene group having 3 to 6 carbon atoms, and R ⁴ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 3 to 6 carbon atoms. Represents a group or a cyclic alkyl group having 3 to 6 carbon atoms. Or 3) R ² represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, and R ³ and R ⁴ represents an alkylene group having 3 to 6 carbon atoms by linking. One of them.
R ⁵ and R ⁸ each independently represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.
Each of R ⁶ and R ⁷ independently represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms; Or R ⁶ and R ⁷ are linked to each other to represent an alkylene group having 3 to 6 carbon atoms.
A and B each independently represent an oxygen atom or a sulfur atom. )
A chemically amplified photoresist composition for extreme ultraviolet exposure, comprising a polymer compound having a repeating unit represented by formula (1) as a constituent unit, a photoacid generator and a solvent. The following general formula (1-1)

(In the formula, R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group. A and B each independently represent an oxygen atom or a sulfur atom.)
A chemically amplified photoresist composition for extreme ultraviolet exposure, comprising a polymer compound having a repeating unit represented by formula (1) as a constituent unit, a photoacid generator and a solvent.   The chemically amplified photoresist composition for extreme ultraviolet exposure according to claim 1 or 2, wherein the photoacid generator is an onium salt.   The chemically amplified photoresist composition for extreme ultraviolet exposure according to claim 3, wherein the onium salt is a fluorine-containing onium salt.   A step of forming a resist film on a substrate using the chemically amplified photoresist composition for extreme ultraviolet exposure according to any one of claims 1 to 4 and exposing the resist film to extreme ultraviolet light, followed by alkali development. And a resist pattern forming method.