JP5585123B2 - Fluorine-containing unsaturated carboxylic acid onium salts - Google Patents

Description

The present invention relates to novel fluorine-containing carboxylic acid onium salts having a polymerizable anion. In particular, KrF excimer laser, ArF excimer laser, near-ultraviolet light generated by the excimer laser or synchrotron radiation, such as F ₂ excimer laser, deep UV, extreme ultraviolet (EUV), a charged particle beam such as an electron beam, soft X-rays, X Resist composition that can be suitably used as a chemically amplified positive resist useful for microfabrication using high-energy rays such as γ-rays and γ-rays, and novel fluorine-containing resins used for the synthesis of new fluororesins that can be used in the composition The present invention relates to fluorine carboxylic acid onium salts.

  In recent years, along with higher integration and higher speed of LSI, pattern rule miniaturization is progressing rapidly. The background of this is the shortening of the wavelength of the exposure light source. For example, by shortening the wavelength from a mercury lamp i-line (365 nm) to a KrF excimer laser (248 nm), a DRAM (dynamic size of 0.25 μm or less) DRAM (dynamic Random access memory) is now available for mass production. Furthermore, ArF lithography using an ArF excimer laser (193 nm) has been studied in earnest in order to realize DRAM manufacturing with an integration degree of 256M and 1G or more, by combining with a high NA lens (NA ≧ 0.9). A 65 nm node device is being studied. ArF immersion lithography has been developed and is now being introduced for 45nm node device fabrication, the next generation. In addition, with a design rule of 45 nm or less, double exposure / double patterning technology applying ArF lithography technology, extreme ultraviolet (EUV) lithography, and the like are considered promising.

  As a resist suitable for such short-wavelength exposure, a “chemically amplified resist composition” has attracted attention. It contains an acid generator (referred to as a “photoacid generator”) that generates an acid upon irradiation with high energy rays (referred to as “exposure”), and the resist film is exposed by a reaction using the generated acid as a catalyst. This is a material for selectively dissolving the resist film in the exposed portion or the non-exposed portion by changing the solubility of the formed portion in the developing solution to form a resist pattern according to the photomask shape.

  By the way, as characteristics required for the photoacid generator in the chemically amplified resist material, it is excellent in transparency to high energy rays, has a high quantum yield in acid generation, has a sufficiently strong acid, The boiling point is sufficiently high, and the diffusion distance (referred to as “diffusion length”) of the generated acid in the resist film is appropriate.

  Among these, regarding the strength, boiling point, and diffusion length of the acid, the structure of the anion moiety is important in the ionic photoacid generator, and the nonionic photoacid having a normal sulfonyl structure or sulfonate structure is used. In the generator, the structure of the sulfonyl moiety is important. For example, in the case of a photoacid generator having a trifluoromethanesulfonyl structure, the generated acid is a sufficiently strong acid and the resolution performance as a photoresist is sufficiently high, but the boiling point of the acid is low and the diffusion length of the acid is long. Therefore, there is a drawback that the photomask dependency as a photoresist increases. Further, in the case of a photoacid generator having a sulfonyl structure bonded to a large organic group such as a 10-camphorsulfonyl structure, the boiling point of the generated acid is sufficiently high and the diffusion length of the acid is sufficiently short. However, since the acid strength is not sufficient, the resolution performance as a photoresist is not sufficient.

  For this reason, as the photoacid generator for the chemically amplified resist composition for ArF excimer laser, those that generate perfluoroalkanesulfonic acid with high acid strength are generally used. The derivatives are problematic in terms of stability (non-degradable) derived from C—F bonds, hydrophobicity, and bioaccumulative properties and accumulation properties derived from lipophilicity. Furthermore, perfluoroalkanesulfonic acids having 5 or more carbon atoms or derivatives thereof are beginning to raise the above problem. In a report by the US Environmental Protection Agency (ENVIRONMENTAL PROTECTION AGENCY), there are proposals to regulate their use.

  Under such circumstances, the number of partially or fully fluorinated carbons having sufficient acidity, suitable acid boiling point and diffusion length, and low environmental impact Development of acid generators that generate low-alkane sulphonic acids has been promoted, and triphenylsulfonium methoxycarbonyldifluoromethanesulfonate (Patent Document 1), (4-methylphenyl) diphenylsulfonyl t-butoxycarbonyldifluoromethanesulfonate (patent) Reference 2) or alkoxycarbonylfluoroalkanesulfonic acid onium salts such as triphenylsulfonium (adamantan-1-ylmethyl) oxycarbonyldifluoromethanesulfonate (Patent Document 3) have been developed as acid generators.

  Recently, however, regulations on perfluoroalkanesulfonic acids (known as PFAS for acronym) are becoming stricter, and alkanesulfones with such a low number of fluorinated carbons, although the number of fluorines is small. There is also concern about the environmental impact of acid generators that generate acids.

  Further, when a higher degree of integration is required, not only a demand for a photoacid generator but also a higher resolution is required for a photosensitive resin composition that is a resist composition. It was. As miniaturization progresses, the demand for reducing the depth of focus margin (hereinafter referred to as “DOF”) and the line edge roughness (hereinafter referred to as “LER”) of the pattern has been increased. As miniaturization progresses in the semiconductor industry, there is an urgent need to develop a resist composition that satisfies such requirements as excellent resolution, wide DOF, low LER, and excellent sensitivity, substrate adhesion, and etching resistance. Yes.

  Under such circumstances, for the purpose of improving sensitivity, a resin (Patent Document 4) having an acroyloxyphenyldiphenylsulfonium salt as a copolymerization component, and the monomer for the purpose of improving LER in a polyhydroxystyrene resin are used. A base resin incorporated as a copolymerization component has been reported (Patent Document 5). However, since the cation side is bonded to the base resin in these, the sulfonic acid generated by irradiation with high energy rays is the same as the sulfonic acid generated from the conventional photoacid generator, and can satisfy the above problems. is not. In addition, for the purpose of improving sensitivity and LER, a sulfonium salt in which an anion side such as polystyrene sulfonic acid is incorporated in a polymer is disclosed (Patent Document 6), and the generated acids are allene sulfonic acid and alkyl sulfone. Since it is an acid derivative and the acid strength of the generated acid is low, it is not sufficient to cleave acid labile groups, particularly acid labile groups of chemically amplified resists using ArF laser light.

  In the immersion exposure, the photoresist film applied and formed on the resist wafer and the lens of the projection exposure apparatus come into contact with an immersion medium such as water. Therefore, the immersion medium may penetrate into the photoresist film, and the resolution of the photoresist may be reduced. Further, there is a problem such as contamination of the lens surface due to dissolution of the constituent components of the photoresist into the immersion medium.

  Furthermore, as an exposure technique after ArF lithography, a fine processing technique using various high energy rays such as extreme ultraviolet rays such as extreme ultraviolet rays (EUV) and charged particle beams such as electron beams is considered promising. , The sulfonic acid component generated from the photoacid generator volatilizes during the exposure because it must be exposed under vacuum (reduced pressure), and a good pattern shape cannot be obtained. May damage the exposure apparatus.

  In order to solve the above-mentioned various lithographic technical problems, partially or completely fluorinated alkanesulfonic acid with a small number of carbon atoms is generated in the side chain, and the generated sulfonic acid component does not volatilize, and the diffusion length is reduced. Polymers having the characteristics of being controllable have been developed (Patent Documents 7 to 10). However, as described above, since there is a concern about the influence on the environment, development of alternative products is being promoted.

  On the other hand, acrylic resin having carboxylic acid in the side chain is often used as a base resin for resist, and resin having fluorocarboxylic acid is also known (Patent Document 11).

JP 2004-117959 A JP 2002-214774 A Japanese Patent Laid-Open No. 2004-4561 JP-A-4-230645 JP 2005-84365 A Japanese Patent No. 3613491 International Publication No. 2006/309446 Pamphlet JP 2006-178317 A JP 2007-197718 A JP 2008-133448 A JP 2009-29802 A

  Excellent pattern shape because it does not contain substances that are likely to affect the environment as described above, has excellent resolution, wide depth of focus (DOF), low line edge roughness (LER), and high sensitivity. The present invention provides a polymerizable monomer (monomer) that can be used to prepare a resist composition capable of forming a resin and that can synthesize a resin having a function as a photoacid generator.

  As a result of intensive studies to solve the above problems, the present inventors have used a resin having a specific fluorine-containing carboxylate structure in the side chain as a photoacid generator, so that the positive resist composition has a resolution. It has been found that a resist composition having a high sensitivity, a large depth of focus margin (DOF), a small line edge roughness (LER), and a high sensitivity can be prepared.

  That is, a resist composition containing a resin obtained by homopolymerizing or copolymerizing the fluorine-containing fluorine-containing carboxylic acid onium salt represented by the general formula (1) is a carboxylic acid onium salt that functions as a photoacid generator. Since the carboxylic acid has two fluorine atoms at the α-position, it generates a very strong carboxylic acid when an acid is generated by irradiation with high energy rays. Therefore, the acid resistance of the base resin contained in the chemically amplified positive resist composition is increased. Since the stable group can be cleaved efficiently, it is highly sensitive to high energy rays.

  In addition, since the polymer type photoacid generator has a site that functions as a chemically amplified photoacid generator fixed to the side chain of the polymer chain, the acid diffusion distance is substantially limited. Although it has the characteristics that the DOF is wide and the LER is small, but the conventional polymer has not yet sufficiently shown the advantages of the polymer type, the present inventors have made the chemistry of the linking group that separates the acid site from the main chain. The inventors have found that the ease of diffusion and the diffusion distance can be adjusted by specifying the structure and the length of the side chain, thereby completing the present invention.

That is, the present invention is as follows.

[Invention 1]
Fluorine-containing unsaturated carboxylic acid onium salt represented by the following general formula (1).

(In the formula, R ¹ represents any of the polymerizable double bond-containing groups represented by the following formula;

R ² represents a fluorine atom or a fluorine-containing alkyl group,
W ¹ represents a divalent organic group,
Q ⁺ represents a sulfonium cation represented by the following general formula (a) or the following general formula (b), or an iodonium cation represented by the following general formula (c).

In the general formula (a), R ³ , R ⁴ and R ⁵ are each independently a substituted or unsubstituted C 1-10 linear or branched alkyl group, alkenyl group or oxoalkyl group, or A substituted or unsubstituted aryl group having 6 to 18 carbon atoms, an aralkyl group or an aryloxoalkyl group, or any two or more of R ³ , R ⁴ and R ⁵ are bonded to each other; A ring may be formed together with the sulfur atom.

In the general formula (b), R ⁶ represents a substituted or unsubstituted linear, branched or cyclic alkyl group or alkenyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms. Indicates a group. m represents an integer of 1 to 5, and n represents 0 (zero) or 1. The substituent for R ⁶ may contain a carbonyl group, a hydroxyl group, an ester, a lactone, an amino group, an amide group, or an ether-bonded oxygen atom.

In the general formula (c), R ⁶ represents a substituted or unsubstituted linear, branched or cyclic alkyl group or alkenyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms. Indicates a group. m represents an integer of 1 to 5, and n represents 0 (zero) or 1. The substituent for R ⁶ may contain a carbonyl group, a hydroxyl group, an ester, a lactone, an amino group, an amide group, or an ether-bonded oxygen atom. )
[Invention 2]
The fluorine-containing unsaturated carboxylic acid onium salt of Invention 1 wherein R ² is a fluorine atom.

[Invention 3]
The fluorine-containing unsaturated carboxylic acid onium salt of the invention 1 or 2, wherein Q ⁺ is a sulfonium cation represented by the general formula (a).

In the general formula (a), R ³ , R ⁴ and R ⁵ are each independently a substituted or unsubstituted C 1-10 linear or branched alkyl group, alkenyl group or oxoalkyl group, or A substituted or unsubstituted aryl group having 6 to 18 carbon atoms, an aralkyl group or an aryloxoalkyl group, or any two or more of R ³ , R ⁴ and R ⁵ are bonded to each other; A ring may be formed together with the sulfur atom.

[Invention 4]
2,2-difluoro-3-methacryloyloxypentanoic acid triphenylsulfonium represented by the following formula:

  The resin having a fluorine-containing carboxylic acid onium salt in the side chain produced by polymerizing or copolymerizing the fluorine-containing unsaturated carboxylic acid onium salt of the present invention itself has an acid labile group and functions as a positive resist. When a resist composition is prepared as a resin to be used, or together with a resin having an acid labile group and functioning as a positive resist, the resolution is excellent, the depth of focus margin (DOF) is wide, and the line edge roughness (LER) is small. In addition, a highly sensitive resist composition can be prepared.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and the following embodiments are performed based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that modifications, improvements, and the like that are appropriately added to the above forms also fall within the scope of the present invention.

<Fluorine-containing unsaturated carboxylic acid onium salt>
Fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1)

In the formula, R ² is a fluorine atom or a fluorine-containing alkyl group. Such a fluorine-containing alkyl group is not particularly limited, but has 1 to 12 carbon atoms, preferably 1 to 3 carbon atoms, trifluoromethyl group, pentafluoroethyl group, 2,2,2 -Trifluoroethyl group, n-heptafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, 3,3,3-trifluoropropyl group, hexafluoroisopropyl group and the like can be mentioned. R ² is more preferably a fluorine atom or a trifluoromethyl group.

R ¹ may be a group having a polymerizable double bond, but is preferably any of a polymerizable double bond-containing group represented by the following formula.

Of these, an acryloyloxy group, a methacryloyloxy group, a trifluoromethacryloyloxy group, and an allyloxy group are more preferable.

The linking group W ¹ represents a single bond or a divalent organic group. The divalent organic group includes an unsubstituted or substituted methylene group, an unsubstituted or substituted divalent alicyclic hydrocarbon group, a divalent aromatic group, an unsubstituted or substituted divalent heterocyclic group, and the like. Or a group consisting of these linking groups and linking groups such as ether-bonded oxygen atoms, ether-bonded sulfur atoms, carbonyl groups, ester groups, oxycarbonyl groups, amide groups, sulfonamide groups, urethane groups, urea groups, etc. A divalent linking group in which one or more selected from the above are bonded to each other, and any number of hydrogen atoms bonded to carbon atoms in the divalent linking group are replaced by fluorine atoms Each carbon atom in the linking group may include a substituent to form a ring.

  The substituted methylene group that is an element of the main skeleton is represented by the following general formula (2).

Here, the monovalent group represented by R ⁷ and R ⁸ of the substituted methylene group is not particularly limited, but is a hydrogen atom, a halogen atom or a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted fat group. A monovalent group having 1 to 30 carbon atoms selected from a cyclic hydrocarbon group, an alkoxyl group, a substituted or unsubstituted aryl group and a substituted or unsubstituted condensed polycyclic aromatic group, The valent group can have a fluorine atom, an oxygen atom, a sulfur atom, a nitrogen atom, or a carbon-carbon double bond. R ⁷ and R ⁸ may be the same or different. R ⁷ and R ⁸ may be combined with atoms in the molecule to form a ring, and this ring preferably has an alicyclic hydrocarbon structure. Examples of the monovalent organic group represented by R ⁷ and R ⁸ include the following.

The acyclic alkyl group for R ⁷ and R ⁸ has 1 to 30 carbon atoms, and preferably 1 to 12 carbon atoms. For example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 1-methylpropyl group, 2-methylpropyl group, tert-butyl group, n-pentyl group, i-pentyl group, 1,1-dimethylpropyl group, 1-methylbutyl group, 1,1-dimethylbutyl group, n-hexyl group, n-heptyl group, i-hexyl group, n-octyl group, i-octyl group, 2-ethylhexyl group , N-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group and the like, and a lower alkyl group is preferable, such as methyl group, ethyl group, n-propyl group, i-propyl group, It can be mentioned as a particularly preferable one. In this specification, “lower” means 1 to 4 carbon atoms, and in the case of a cyclic compound, it means 3 to 7 carbon atoms.

As the acyclic substituted alkyl group in R ⁷ and R ⁸ , one or more hydrogen atoms of the alkyl group are substituted with 1 to 4 carbon atoms alkoxyl group, halogen atom, acyl group, acyloxy group, cyano. Group, a hydroxyl group, a carboxy group, an alkoxycarbonyl group, a nitro group and the like, and a fluoroalkyl group substituted with a fluorine atom is preferred, and specifically, a trifluoromethyl group, a pentafluoroethyl group 2,2,2-trifluoroethyl group, n-heptafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, 3,3,3-trifluoropropyl group, hexafluoroisopropyl group, etc. Of lower fluoroalkyl groups.

The alicyclic hydrocarbon group for R ⁷ and R ^{8 or} the alicyclic hydrocarbon group formed including the carbon atom to which they are bonded may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 3 or more carbon atoms. The number of carbon atoms is preferably 3 to 30, and particularly preferably 3 to 25 carbon atoms. These alicyclic hydrocarbon groups may have a substituent.

  As the monocyclic group, those having 3 to 12 ring carbon atoms are preferable, and those having 3 to 7 ring carbon atoms are more preferable. For example, preferred are a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecanyl group, a cyclododecanyl group, and a 4-tert-butylcyclohexyl group. Examples of the polycyclic group include an adamantyl group having 7 to 15 ring carbon atoms, a noradamantyl group, a decalin residue, a tricyclodecanyl group, a tetracyclododecanyl group, a norbornyl group, and a cedrol group. . The alicyclic hydrocarbon group may be a spiro ring, and is preferably a C 3-6 spiro ring. An adamantyl group, a decalin residue, a norbornyl group, a cedrol group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecanyl group, a cyclododecanyl group, a tricyclodecanyl group and the like are preferable. One or more of the ring carbons of these organic groups or the hydrogen atoms of the linking group are each independently the alkyl group or substituted alkyl group having 1 to 30 carbon atoms, hydroxyl group, alkoxyl group, carboxyl group, alkoxycarbonyl. Examples thereof include monocyclic groups in which one or two or more hydrogen atoms contained therein are substituted with a fluorine atom or a trifluoromethyl group.

  Here, the alkyl group having 1 to 30 carbon atoms is preferably a lower alkyl group, more preferably an alkyl group selected from the group consisting of a methyl group, an ethyl group, a propyl group, and an isopropyl group. In addition, examples of the substituent of the substituted alkyl group include a hydroxyl group, a halogen atom, and an alkoxyl group. Examples of the alkoxyl group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, and an isopropoxycarbonyl group.

Examples of the alkoxyl group in R ⁷ and R ⁸ include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

The substituted or unsubstituted aryl group for R ⁷ and R ⁸ has 1 to 30 carbon atoms. Monocyclic groups are preferably those having 3 to 12 ring carbon atoms, and more preferably those having 3 to 6 ring carbon atoms. For example, phenyl group, biphenyl group, terphenyl group, o-tolyl group, m-tolyl group, p-tolyl group, p-hydroxyphenyl group, p-methoxyphenyl group, mesityl group, o-cumenyl group, 2, 3 -Xylyl group, 2,4-xylyl group, 2,5-xylyl group, 2,6-xylyl group, 3,4-xylyl group, 3,5-xylyl group, o-fluorophenyl group, m-fluorophenyl group P-fluorophenyl group, o-trifluoromethylphenyl group, m-trifluoromethylphenyl group, p-trifluoromethylphenyl group, 2,3-bistrifluoromethylphenyl group, 2,4-bistrifluoromethylphenyl group 2,5-bistrifluoromethylphenyl group, 2,6-bistrifluoromethylphenyl group, 3,4-bistrifluoromethylphenyl group Group, 3,5-bis-trifluoromethylphenyl group, p- chlorophenyl group, p- bromophenyl group, and a p- iodophenyl group.

  Examples of the substituted or unsubstituted condensed polycyclic aromatic group having 1 to 30 carbon atoms include pentalene, indene, naphthalene, azulene, heptalene, biphenylene, indacene, acenaphthylene, fluorene, phenalene, phenanthrene, anthracene, fluoranthene, and acephenant. One hydrogen atom is removed from rylene, asanthrylene, triphenylene, pyrene, chrysene, naphthacene, picene, perylene, pentaphen, pentacene, tetraphenylene, hexaphene, hexacene, rubicene, coronene, trinaphthylene, heptaphene, heptacene, pyranthrene, ovalen, etc. The monovalent organic group obtained by the above can be exemplified, and one or more of these hydrogen atoms are substituted with a fluorine atom, an alkyl group having 1 to 4 carbon atoms or a fluorine-containing alkyl group. It may be mentioned as preferred one.

  Examples of the monocyclic or polycyclic heterocyclic group having 3 to 25 ring atoms include pyridyl group, furyl group, thienyl group, pyranyl group, pyrrolyl group, thiantenyl group, pyrazolyl group, isothiazolyl group, isoxazolyl group, Pyrazinyl group, pyrimidinyl group, pyridazinyl group, tetrahydropyranyl group, tetrahydrofuranyl group, tetrahydrothiopyranyl group, tetrahydrothiofuranyl group, 3-tetrahydrothiophene-1,1-dioxide group and the like and atoms constituting these rings And a heterocyclic group in which one or more hydrogen atoms are substituted with an alkyl group, an alicyclic hydrocarbon group, an aryl group, or a heterocyclic group. Moreover, what has a monocyclic or polycyclic ether ring and a lactone ring is preferable, and it illustrates next.

In formula, R ^<a> , R ^<b > represents a hydrogen atom and a C1-C4 alkyl group each independently. n represents an integer of 2 to 4.

The divalent alicyclic hydrocarbon group constituting the main skeleton of the linking group W ¹ may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 3 or more carbon atoms. The number of carbon atoms is preferably 3 to 30, and particularly preferably 3 to 25 carbon atoms. These alicyclic hydrocarbon groups may have a substituent.

  As the monocyclic group, those having 3 to 12 ring carbon atoms are preferable, and those having 3 to 7 ring carbon atoms are more preferable. For example, preferred are a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclodecanylene group, a cyclododecanylene group, and a 4-tert-butylcyclohexylene group. it can. In addition, examples of the polycyclic group include adamantylene group having 7 to 15 ring carbon atoms, noradamantylene group, divalent residue of decalin, tricyclodecanylene group, tetracyclododecanylene group, norbornylene group, cedrol. Mention may be made of divalent residues. The alicyclic hydrocarbon group may be a spiro ring, in which case a C 3-6 spiro ring is preferred. Also, one or more of the ring carbon or hydrogen atoms of the linking group are each independently substituted with an alkyl group having 1 to 30 carbon atoms or a substituted alkyl group, a hydroxyl group, an alkoxyl group, a carboxyl group, or an alkoxycarbonyl group. Things can be mentioned.

  Here, the alkyl group having 1 to 30 carbon atoms is preferably a lower alkyl group, more preferably an alkyl group selected from the group consisting of a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the substituent of the substituted alkyl group include a hydroxyl group, a halogen atom, and an alkoxyl group. Examples of the alkoxyl group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, and an isopropoxycarbonyl group.

Examples of the divalent aromatic hydrocarbon group constituting the main skeleton of the linking group W ¹ include a monocyclic group having 1 to 30 carbon atoms or a condensed polycyclic aromatic group. Monocyclic groups are preferably those having 3 to 12 ring carbon atoms, and more preferably those having 3 to 6 ring carbon atoms. For example, benzene, biphenyl, terphenyl, toluene, phenol, anisole, mesitylene, cumene, 2,3-xylylene, 2,4-xylene, 2,5-xylene, 2,6-xylene, 3,4-xylene, 3 , 5-xylene, fluorobenzene, trifluoromethylbenzene, o-bistrifluoromethylbenzene, m-bistrifluoromethylbenzene, p-bistrifluoromethylbenzene, chlorobenzene, bromobenzene, iodobenzene, etc., excluding two hydrogen atoms Can be mentioned.

  The condensed polycyclic aromatic group can be substituted or unsubstituted, preferably has 1 to 30 carbon atoms, pentalene, indene, naphthalene, azulene, heptalene, biphenylene, indacene, acenaphthylene, fluorene, phenalene, phenanthrene, Anthracene, fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, naphthacene, picene, perylene, pentaphen, pentacene, tetraphenylene, hexaphene, hexacene, rubicene, coronene, trinaphthylene, heptaphene, heptacene, pyranthrene, ovalene, etc. And divalent organic groups obtained by removing two hydrogen atoms from the above, wherein one or more of these hydrogen atoms are a fluorine atom, an alkyl group having 1 to 4 carbon atoms, or It can by fluorine alkyl group is obtained by replacing.

The monocyclic or polycyclic heterocyclic group having 3 to 25 ring atoms constituting the main skeleton of W ¹ may be an aromatic ring or a non-aromatic ring. For example, pyridine, furan, Divalent obtained by removing two hydrogen atoms from thienine, pyranine, pyrroline, thianthrene, pyrazone, isothiazone, isoxazone, pyrazine, pyrimidine, pyridazine, tetrahydropyranine, tetrahydrofuranine, tetrahydrothiopyranine, tetrahydrothiofuran, etc. Heterocycle in which one or more hydrogen atoms of the atoms constituting the organic group and these rings are substituted with an alkyl group (preferably a lower alkyl group), an alicyclic hydrocarbon group, an aryl group, or a heterocyclic group The group can be mentioned. Of these, monocyclic or polycyclic ether rings are preferred, and they are exemplified below. In the formula, the line segment at the open end indicates a dangling bond.

As described above, the linking group W ¹ may be a divalent group obtained by combining the divalent groups described in the above general formula or specifically exemplified.

  Further, from the group consisting of the above linking group and a linking group such as an ether bondable oxygen atom, an ether bondable sulfur atom, a carbonyl group, an ester group, an oxycarbonyl group, an amide noble, a sulfonamide group, a urethane group, and a urea group. It may be a divalent linking group in which one or more selected ones are bonded to each other, and the following structures can be exemplified. In the formula, each of O and C represents an oxygen atom and a carbon atom adjacent to the substituted methylene group.

The linking group W ^1, substituted methylene group represented by the general formula (2) is most preferred. Specific preferred examples of the substituted methylene group represented by the general formula (2) are shown below. In the formula, each of O and C represents an oxygen atom and a carbon atom adjacent to the substituted methylene group.

Q ⁺ represents a sulfonium cation represented by the following general formula (a) or the following general formula (b), or an iodonium cation represented by the following general formula (c).

In the general formula (a), R ³ , R ⁴ and R ⁵ are each independently a substituted or unsubstituted C 1-10 linear or branched alkyl group, alkenyl group or oxoalkyl group, or A substituted or unsubstituted aryl group having 6 to 18 carbon atoms, an aralkyl group or an aryloxoalkyl group, or any two or more of R ³ , R ⁴ and R ⁵ are bonded to each other; A ring may be formed together with the sulfur atom.

In the general formula (b), R ⁶ represents a substituted or unsubstituted linear, branched or cyclic alkyl group or alkenyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms. Indicates a group. m represents an integer of 1 to 5, and n represents 0 (zero) or 1.

In the general formula (c), R ⁶ represents a substituted or unsubstituted linear, branched or cyclic alkyl group or alkenyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms. Indicates a group. m represents an integer of 1 to 5, and n represents 0 (zero) or 1. )
Hereinafter, the sulfonium cation represented by the general formula (a) and the general formula (b) and the iodonium cation represented by the general formula (c) and the general formula (d) will be described in detail.

[Sulfonium Cation Shown by General Formula (a)]
Specific examples of R ³ , R ⁴ and R ⁵ in the general formula (a) include the following. As the alkyl group, methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, n-pentyl group, cyclopentyl group, n- Hexyl group, n-heptyl group, 2-ethylhexyl group, cyclohexyl group, cycloheptyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, n-octyl group, n-decyl group, 1-adamantyl group, 2-adamantyl group, Bicyclo [2.2.1] hepten-2-yl group, 1-adamantanemethyl group, 2-adamantanemethyl group and the like can be mentioned. Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group. Examples of the oxoalkyl group include 2-oxocyclopentyl group, 2-oxocyclohexyl group, 2-oxopropyl group, 2-oxoethyl group, 2-cyclopentyl-2-oxoethyl group, 2-cyclohexyl-2-oxoethyl group, 2- ( And 4-methylcyclohexyl) -2-oxoethyl group. As the aryl group, phenyl group, naphthyl group, thienyl group and the like, p-methoxyphenyl group, m-methoxyphenyl group, o-methoxyphenyl group, p-ethoxyphenyl group, p-tert-butoxyphenyl group, m-tert. -Alkoxyphenyl groups such as butoxyphenyl group, alkylphenyl groups such as 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, and ethylphenyl group; alkylnaphthyl groups such as methylnaphthyl group and ethylnaphthyl group; Dialkylnaphthyl groups such as diethylnaphthyl group, 2-methoxy-1-naphthyl group, 4-methoxy-1-naphthyl group, 2-ethoxy-1-naphthyl group, 4-ethoxy-1-naphthyl group, 2-butoxy-1 -Monoalkoxynaphthyl groups such as naphthyl group and 4-butoxy-1-naphthyl group; Tokishinafuchiru group, dialkoxy naphthyl group such as diethoxy naphthyl group. Examples of the aralkyl group include a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group. As the aryloxoalkyl group, 2-aryl-2-oxoethyl group such as 2-phenyl-2-oxoethyl group, 2- (1-naphthyl) -2-oxoethyl group, 2- (2-naphthyl) -2-oxoethyl group and the like Groups and the like. When any two or more of R ³ , R ⁴ and R ⁵ are bonded to each other to form a cyclic structure via a sulfur atom, 1,4-butylene, 3-oxa-1, 5-pentylene etc. are mentioned, Furthermore, the cyclic structure of the following structure can be mentioned. (In the following formula, any of the substituents R ³ , R ⁴ or R ⁵ is bonded to the bond represented by a broken line.)

  Furthermore, aryl groups having polymerizable substituents such as an acryloyloxy group and a methacryloyloxy group can be mentioned as a substituent, specifically, 4- (acryloyloxy) phenyl group, 4- (methacryloyloxy) phenyl group, 4 -Vinyloxyphenyl group, 4-vinylphenyl group, etc. are mentioned.

  More specifically, preferred sulfonium cations represented by general formula (a) are triphenylsulfonium, (4-tert-butylphenyl) diphenylsulfonium, bis (4-tert-butylphenyl) phenylsulfonium, tris (4- tert-butylphenyl) sulfonium, (3-tert-butylphenyl) diphenylsulfonium, bis (3-tert-butylphenyl) phenylsulfonium, tris (3-tert-butylphenyl) sulfonium, (3,4-ditert-butyl) Phenyl) diphenylsulfonium, bis (3,4-ditert-butylphenyl) phenylsulfonium, tris (3,4-ditert-butylphenyl) sulfonium, bis (4-tert-butoxyphenyl) phenylsulfone , Tris (4-tert-butoxyphenyl) sulfonium, (3-tert-butoxyphenyl) diphenylsulfonium, bis (3-tert-butoxyphenyl) phenylsulfonium, tris (3-tert-butoxyphenyl) sulfonium, (3 4-ditert-butoxyphenyl) diphenylsulfonium, bis (3,4-ditert-butoxyphenyl) phenylsulfonium, tris (3,4-ditert-butoxyphenyl) sulfonium, diphenyl (4-thiophenoxyphenyl) sulfonium, Tris (4-tert-butoxycarbonylmethyloxyphenyl) sulfonium, (4-tert-butoxyphenyl) bis (4-dimethylaminophenyl) sulfonium, tris (4-dimethylaminophen L) sulfonium, 2-naphthyldiphenylsulfonium, dimethyl (2-naphthyl) sulfonium, (4-hydroxyphenyl) dimethylsulfonium, (4-methoxyphenyl) dimethylsulfonium, trimethylsulfonium, (2-oxocyclohexyl) cyclohexylmethylsulfonium, tri Naphthylsulfonium, tribenzylsulfonium, diphenylmethylsulfonium, dimethylphenylsulfonium, 2-oxo-2-phenylethylthiacyclopentanium, diphenyl 2-thienylsulfonium, 4-n-butoxynaphthyl-1-thiacyclopentanium, 2- n-butoxynaphthyl-1-thiacyclopentanium, 4-methoxynaphthyl-1-thiacyclopentanium, 2-methoxynaphthyl-1-thiaci Lopentanium, 5-phenyldibenzothiophenium, 5- (4-hydroxyphenyl) dibenzothiophenium, 5- (4-methylphenyl) dibenzothiophenium, 5- (4-t-butylphenyl) dibenzothiophenium Examples thereof include 10-phenylphenoxathinium, 10- (4-hydroxyphenyl) phenoxathinium, 10- (4-tert-butoxyphenyl) phenoxathinium, and a sulfonium cation having the following structure.

  More preferably, triphenylsulfonium, (4-tert-butylphenyl) diphenylsulfonium, (4-tert-butoxyphenyl) diphenylsulfonium, tris (4-tert-butylphenyl) sulfonium, (4-tert-butoxycarbonylmethyloxyphenyl) ) Diphenylsulfonium and the like.

    Furthermore, 4- (methacryloyloxy) phenyldiphenylsulfonium, 4- (acryloyloxy) phenyldiphenylsulfonium, 4- (methacryloyloxy) phenyldimethylsulfonium, 4- (acryloyloxy) phenyldimethylsulfonium and the like can be mentioned. Regarding these polymerizable sulfonium cations, reference can be made to JP-A-4-230645 and JP-A-2005-84365.

[Sulfonium Cation Shown by General Formula (b)]
The substitution position of the R ^6- (O) _n -group in the general formula (b) is not particularly limited, but the 4-position or 3-position of the phenyl group is preferable. More preferably, it is the 4th position. Here, n is 0 (zero) or 1. Specific examples of R ⁶ include methyl group, ethyl group, n-propyl group, sec-propyl group, cyclopropyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, n -Pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, n-octyl group, n-decyl group, n-dodecyl group, 1-adamantyl group, 2-adamantyl group, bicyclo [2.2.1] heptene- 2-yl group, phenyl group, 4-methoxyphenyl group, 4-tert-butylphenyl group, 4-biphenyl group, 1-naphthyl group, 2-naphthyl group, 10-anthranyl group, 2-furanyl group, and n = In the case of 1, an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group are exemplified.

    Specific sulfonium cations include (4-methylphenyl) diphenylsulfonium, (4-ethylphenyl) diphenylsulfonium, (4-cyclohexylphenyl) diphenylsulfonium, (4-n-hexylphenyl) diphenylsulfonium, (4-n -Octyl) phenyldiphenylsulfonium, (4-methoxyphenyl) diphenylsulfonium, (4-ethoxyphenyl) diphenylsulfonium, (4-tert-butoxyphenyl) diphenylsulfonium, (4-cyclohexyloxyphenyl) diphenylsulfonium, (4-tri Fluoromethylphenyl) diphenylsulfonium, (4-trifluoromethyloxyphenyl) diphenylsulfonium, (4-tert-butoxycarbonylmethylo) Shifeniru) diphenyl sulfonium, and the like.

[Iodonium cation represented by general formula (c)]
The substitution position of the R ^6- (O) _n -group in the general formula (c) is not particularly limited, but the 4-position or 3-position of the phenyl group is preferable. More preferably, it is the 4th position. Here, n is 0 (zero) or 1. Specific examples of R ⁶ may be mentioned again the same as R ⁶ in formula (b).

    Specific iodonium cations include bis (4-methylphenyl) iodonium, bis (4-ethylphenyl) iodonium, bis (4-tert-butylphenyl) iodonium, bis (4- (1,1-dimethylpropyl) phenyl. ) Iodonium, (4-methoxyphenyl) phenyliodonium, (4-tert-butoxyphenyl) phenyliodonium, 4- (acryloyloxy) phenylphenyliodonium, 4- (methacryloyloxy) phenylphenyliodonium, and the like. (4-tert-butylphenyl) iodonium is preferably used.

<Method for producing fluorine-containing unsaturated carboxylic acid onium salt>
Next, a method for producing the fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1) will be described.

  The fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1) is a fluorine-containing unsaturated carboxylic acid represented by the general formula (4).

^{(Wherein, R 1, R 2, W 1} , Q + has the general formula (1) in ^{R 1, R 2, W 1} , Q + as synonymous.) Can be synthesized in the starting material It is.

  Such a fluorine-containing unsaturated carboxylic acid can be produced using the method shown in the following reaction formula [1] to reaction formula [3] as described in JP-A-2009-29802.

Wherein, ^{R 1} and ^{R 2} have the same meanings as ^{R 1} and ^{R 2} in the general formula (1). R ^d , R ^e and R ^f each independently represent a monovalent organic group, and R ^d is particularly preferably a hydrogen atom. R ^d and R ^e correspond to R ⁷ or R ⁸ in the general formula (2), and the specific description is as described above. The monovalent organic group is preferably an alkyl group, specifically, methyl group, ethyl group, propyl group, butyl group, cyclopentyl group, cyclohexyl group, norbornyl group, adamantyl group, trifluoromethyl group, 2,2 , 2-trifluoroethyl group, 1- (trifluoromethyl) ethyl group and 3,3,3-trifluoropropyl group, and cyclopentyl group, cyclohexyl group or cycloheptyl group formed by bonding R ^d or ^Re to each other Groups. Here, substituted methylene group are exemplified as specific examples listed as the preferred are preferred ^(-CR d ^{R e} - -) is ^(-CR 7 ^{R 8).} Y represents a halogen atom (fluorine, chlorine, bromine, iodine), a trifluoromethanesulfonate group, an alkylsulfonate group having 1 to 4 carbon atoms, an arylsulfonate group, or the like. W represents a divalent linking group, and W—O—CR ^d R ^e corresponds to one embodiment of W ¹ in the general formula (1).

Here, by reacting a halogen-containing carboxylic acid ester (i) having an active halogen fluorine atom at the α-position and a carbonyl compound (ii) in an anhydrous state in the presence of zinc (Reformatsky reaction), a hydroxycarboxylic acid ester (iii) (Scheme [1]). Subsequently, the obtained hydroxycarboxylic acid ester (iii) and the halogenated compound (iv) having a polymerizable double bond are reacted in a solvent in the presence of a base to obtain an unsaturated carboxylic acid ester (v) (reaction formula [2] ]). Next, the obtained ester (v) is hydrolyzed to obtain an unsaturated carboxylic acid (vi) having a fluorine atom at the α-position (reaction formula [3]). In the general formula (vi), W—O—CR ^d R ^e is included in W ¹ , and the general formula (vi) is an example showing one embodiment of the general formula (1).

  The fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1) can be obtained by mixing the fluorine-containing unsaturated carboxylic acid represented by the general formula (4) and the corresponding onium salt. Also, the fluorine-containing unsaturated carboxylic acid represented by the general formula (4) is reacted with an inorganic base to form an inorganic salt (first step), and the resulting inorganic salt is allowed to act on the corresponding onium salt to exchange onium salts. The second method is an efficient method. The inorganic base is not particularly limited and can be used regardless of the valence, but an alkali metal salt is preferably used (Scheme 1).

^{(Wherein, R 1, R 2, W} 1, Q + is, ^{R 1,} is R ^2, W ^{1, Q +} as synonymous in the general formula (1) .B ^- and X ^- is each a monovalent anion M ⁺ represents a monovalent alkali metal cation.)
First, the first step will be described. When the inorganic base is monovalent, the molar ratio of the inorganic base to the fluorine-containing unsaturated carboxylic acid represented by the general formula (4) is usually 0.9 to 3.0, preferably 1.0 to 1.5. Yes, more preferably 1.0 to 1.2. A target inorganic salt can be obtained even at a molar ratio of 1.0 or less, but the yield is lowered, which is not preferable. Therefore, it is preferable to use an inorganic base having a molar ratio of 1.0 or more. Although it is possible to use an inorganic base having a molar ratio of 1.5 or more, it is not preferable because the efficiency of onium salt exchange in the second step is lowered. When the inorganic base is divalent, it is preferable to use an amount that is half that of the monovalent case described above.

  As described above, the inorganic base is not particularly limited and can be used regardless of the valence, but an alkali metal salt is preferably used. Examples of the alkali metal salt include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal hydrogen carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate, and alkali metal carbonates such as sodium carbonate and potassium carbonate. Suitable examples include alkali metal hydroxides.

  This reaction usually uses an aqueous solution of an inorganic base. Although there is no restriction | limiting in particular in the density | concentration of aqueous solution, Since efficiency is bad at too thin density | concentration, the density | concentration of 5%-48% is preferable.

  The reaction can proceed by mixing the fluorine-containing unsaturated carboxylic acid represented by the general formula (4) and an aqueous inorganic base solution.

  Moreover, water and an organic solvent can be used together as needed. There is no restriction | limiting in particular in the organic solvent used together. Organic solvents that are not miscible with water, such as organic solvents that can extract the fluorine-containing unsaturated carboxylic acid inorganic salt represented by the general formula (5) from the aqueous layer, for example, halogenated alkyls such as methylene chloride and chloroform, are preferred.

  The reaction temperature is usually 0 to 100 ° C., preferably 5 to 80 ° C., and the reaction time is usually 10 minutes to 16 hours, preferably 30 minutes to 6 hours, but thin layer chromatography (TLC) It is preferable to use an analytical instrument such as a nuclear magnetic resonance apparatus (NMR) or the like as the end point of the reaction when the fluorine-containing unsaturated carboxylic acid represented by the general formula (4) is consumed.

  The fluorine-containing unsaturated carboxylic acid inorganic salt represented by the general formula (5) thus obtained can be extracted with an organic solvent or purified by recrystallization as necessary.

  However, it is possible to extract the fluorine-containing unsaturated carboxylic acid inorganic salt represented by the general formula (5) from the aqueous layer, use an organic solvent that is not mixed with water, and add only the required amount of an aqueous inorganic base solution. It is an efficient method to proceed to the next second step without isolating the fluorine-containing unsaturated carboxylic acid inorganic salt. As the organic solvent, alkyl halides can be used, and examples thereof include methylene chloride and chloroform.

  Next, the second step will be described. In the second step, the fluorine-containing unsaturated carboxylic acid inorganic salt represented by the general formula (5) obtained in the first step is converted into a monovalent onium salt represented by the general formula (6).

(Wherein, Q ⁺ has the same meaning as Q ⁺ in the general formula (1) .X ^-. Is showing a monovalent anion) and an onium salt exchange with a fluorine-containing represented by the general formula (1) This is a step (onium salt exchange step) for obtaining an unsaturated carboxylic acid onium salt.

As Q ⁺ used here, the above-mentioned Q ⁺ can be exemplified again.

Examples of the monovalent anion of X ⁻ in the general formula (6) include F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , HSO ₄ ⁻ , H ₂ PO ₄ ⁻ , BF ₄ ⁻ and PF _6. ⁻ , SbF ₆ ⁻ , aliphatic sulfonate anion, aromatic sulfonate anion, trifluoromethanesulfonate anion, fluorosulfonate anion, aliphatic carboxylate anion, aromatic carboxylate anion, fluorocarboxylate anion, trifluoroacetate anion Preferred are Cl ⁻ , Br ⁻ , HSO ₄ ⁻ , BF ₄ ⁻ , aliphatic sulfonate ions, etc., and more preferred are Cl ⁻ , Br ⁻ and HSO ₄ ^— .

  The molar ratio of the monovalent onium salt represented by the general formula (6) to the fluorine-containing unsaturated carboxylic acid inorganic salt represented by the general formula (5) is usually 0.5 to 10.0, preferably 0.00. It is 8-2.0, More preferably, it is 0.9-1.2.

This reaction is usually performed in a reaction solvent. The reaction solvent is preferably water or an organic solvent such as lower alcohols, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, more preferably Water, methanol, N, N-dimethylacetamide, acetonitrile, dichloromethane, chloroform and the like are particularly preferable water, dichloromethane and chloroform.
The reaction temperature is usually 0 to 80 ° C., preferably 5 to 30 ° C., and the reaction time is usually 10 minutes to 16 hours, preferably 30 minutes to 6 hours, but thin layer chromatography (TLC) It is preferable to use an analytical instrument such as a nuclear magnetic resonance apparatus (NMR) or the like, and to set the end point of the reaction at the time when the raw fluorine-containing unsaturated carboxylic acid inorganic salt represented by the general formula (5) is consumed.

  The fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1) thus obtained may be concentrated as necessary, or the solvent may be distilled off after extraction with an organic solvent. And can be taken out as a solid. The organic solvent used for extraction here is an organic solvent that is not mixed with water, for example, esters such as ethyl acetate and n-butyl acetate; ethers such as diethyl ether; alkyl halides such as methylene chloride and chloroform. And the like.

  The extracted solid can also be purified by a method such as recrystallization. Thus, the target fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1) can be obtained.

<Resin containing fluorinated carboxylic acid onium salt>
A resin containing a fluorine-containing carboxylic acid onium salt can be produced by homopolymerizing or copolymerizing the fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1) of the present invention.

When this resin is exposed to high energy rays, Q ⁺ is eliminated and the terminal of the subsequent repeating unit is converted to difluorocarboxylic acid. Here, the high energy beam is not particularly limited, but charged particle beam such as near ultraviolet ray, far ultraviolet ray, extreme ultraviolet ray (EUV), electron beam generated by excimer laser such as KrF excimer laser or ArF excimer laser or synchrotron radiation, soft beam, soft High energy rays such as X-rays, X-rays and γ-rays can be exemplified, and in particular, when performing fine processing, near ultraviolet rays generated by excimer lasers such as KrF excimer laser and ArF excimer laser and synchrotron radiation, High energy rays having a wavelength of 300 nm or less such as far ultraviolet rays and extreme ultraviolet rays (EUV) are effective.

The terminal of the repeating unit after elimination of Q ⁺ is difluorocarboxylic acid, which shows very strong acidity and functions as a photoacid generator for a chemically amplified resist composition. Therefore, the resin containing a fluorine-containing carboxylic acid onium salt obtained by homopolymerizing or copolymerizing the fluorine-containing unsaturated carboxylic acid onium salt represented by the general formula (1) of the present invention functions as a photoacid generator. In addition, when the resin has a photosensitive solubility changing function alone, when the resin does not have a photosensitive solubility changing function, at least a combination with a resin having a photosensitive solubility changing function, and further includes at least a solvent. Can be used as a resist composition.

  As a resin containing a fluorine-containing carboxylic acid onium salt, a resin comprising a repeating unit formed from a fluorine-containing carboxylic acid onium salt having a structure represented by the general formula (1) depending on the purpose of use, or an acid labile group A carboxylate resin composed of a repeating unit having a repeating unit formed from a fluorine-containing carboxylic acid onium salt can be used, and any of these is another repeating unit (referred to as “secondary repeating unit” in this specification). Can be included. The secondary repeating unit refers to a repeating unit that does not correspond to either a repeating unit formed from a fluorine-containing carboxylic acid onium salt or a repeating unit having an acid labile group. The secondary monomer is a monomer in which a double bond is cleaved to form a secondary repeating unit.

  Therefore, the resin containing a fluorine-containing carboxylic acid onium salt is a repeating unit formed from a fluorine-containing carboxylic acid onium salt obtained by homopolymerizing a fluorine-containing carboxylic acid onium salt having a structure represented by the general formula (1). It may be a homopolymer consisting only of or may contain secondary repeating units. Although these cannot be used as positive resists themselves, they can constitute a resist composition as a photoacid generator together with a base resin.

<Acid labile group>
The acid labile group in the resin containing the fluorine-containing carboxylic acid onium salt having a photolytic solubility-changing function of the present invention is a group dissociated by an acid generated from a site having an acid generator function such as an acid generator by the action of light. And known ones can be used. A chemical amplification type is preferable, and examples thereof include a 1,1-dimethylpropyl group.

<Base resin>
In this specification, the base resin refers to a resin having an acid labile group and a positive resist function. The resin containing the fluorine-containing carboxylic acid onium salt having the photolytic solubility changing function is also one form of the base resin.

  The resist composition for chemical amplification generally contains a base resin, a photoacid generator, and a solvent. In addition to these, additives such as a basic compound and a dissolution inhibitor may be added as necessary. it can.

  The base resin used in the positive resist composition is a resin having a hydroxyl group contained in a carboxyl group, hydroxyphenyl group, or the like protected with an acid labile group in the side chain as an elimination site. The main chain is composed of repeating units formed by cleavage of a polymerizable double bond.

  The base resin is often a copolymer for adjusting resist characteristics, and various resins have been proposed.

  These base resins can contain a repeating unit of a resin containing the fluorine-containing carboxylic acid onium salt. This base resin also has a function as a photoacid generator possessed by a resin containing a fluorine-containing carboxylic acid onium salt, and a positive resist composition is prepared only from a base resin having an acid labile group and a solvent. You can also. These resist compositions can also be used in combination with a known photoacid generator. Furthermore, other additive components that are usually used in the field of resist compositions can be used in combination.

<Basic compound>
In addition, the resist composition according to the polymerizable monomer of the present invention contains a basic compound as an optional component as a quencher or to improve the resist pattern shape, stability over time, etc. It is preferable to make it.

  This basic compound component may be a known one, for example, primary, secondary, tertiary aliphatic amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a hydroxyphenyl group, alcohols Nitrogenous compounds, amide derivatives and the like can be used, among which secondary aliphatic amines, tertiary aliphatic amines, aromatic amines and heterocyclic amines are preferred. These may be used alone or in combination of two or more.

<Solvent>
As a method of forming the fluorine-containing polymer compound into a thin film, for example, a method of forming a film by dissolving in an organic solvent and applying and drying can be used. The organic solvent to be used is not particularly limited as long as the fluorine-containing polymer compound is soluble. A solvent may be used independently and may be used in mixture of 2 or more types.

<Acid generator>
In the resist composition according to the polymerizable monomer of the present invention, a known photoacid generator can be used together with a resin containing a fluorine-containing carboxylic acid onium salt. As the photoacid generator, an arbitrary one can be selected from those used as the acid generator of the chemically amplified resist. A photo-acid generator may be used independently and may be used in combination of 2 or more type.

<Pattern formation method>
As a method of using the resist composition according to the polymerizable monomer of the present invention, a resist pattern forming method of a conventional photoresist technique can be used. That is, first, a resist composition solution is applied to a substrate such as a silicon wafer or a glass plate coated with a chromium thin film using a spinner or the like, and dried to form a photosensitive layer. A high energy beam or an electron beam is irradiated through a desired mask pattern and heated. Next, this is developed using a developer, for example, an alkaline aqueous solution such as a 0.1 to 10% by mass tetramethylammonium hydroxide aqueous solution. With this forming method, a pattern faithful to the mask pattern can be obtained. Further, additives that are miscible with the resist composition as desired, such as additional resins, quenchers, plasticizers, stabilizers, colorants, surfactants, thickeners, leveling agents, antifoaming agents, compatibilizing agents. Various additives such as an adhesive and an antioxidant can be contained.

  The high energy rays used in the resist material according to the polymerizable monomer of the present invention are not particularly limited. However, particularly in the case of performing fine processing, near-ultraviolet rays (wavelength 380 to 200 nm) such as ArF excimer laser and KrF excimer laser, or vacuum Ultraviolet rays (far ultraviolet rays, VUV, wavelength of 200 to 10 nm), extreme ultraviolet rays such as synchrotron radiation (EUV, wavelength of 10 nm or less), soft X-rays, X-rays, γ-rays, etc., which are 300 nm or less and electron beams are effective. . In the pattern forming method of the present invention, it is effective to use an exposure apparatus provided with such a high-energy ray or electron beam source having a short wavelength of 300 nm or less. An immersion exposure system that uses a medium that absorbs less high-energy rays, such as water or a fluorine-based solvent, in part of the optical path and enables more efficient microfabrication at the same numerical aperture and effective wavelength. Is effective, and the resist composition according to the polymerizable monomer of the present invention is also suitable for use in such an apparatus.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, reference examples, and reference comparative examples, but the present invention is not limited to the following examples. In the following examples, Me represents a methyl group. The copolymer composition ratio is a molar ratio, and the weight average molecular weight (Mw) indicates a polystyrene-converted weight average molecular weight by gel permeation chromatography (GPC).

[Example 1]
Synthesis of triphenylsulfonium 2,2-difluoro-3-methacryloyloxypentanoate

To a 1 L glass flask equipped with a dropping funnel were added 108 g (0.486 mol) of 1-hydroxycarbonyl-1,1-difluoro-2-butyl methacrylate and 108 g of chloroform, and the mixture was cooled to 0 ° C. and stirred. Thereafter, 224 g (0.560 mol / 1.15 equivalent) of a 10% by mass aqueous sodium hydroxide solution was added dropwise, and the mixture was stirred at room temperature for 1 hour. Thereafter, a solution prepared by dissolving 169 g (0.492 mol / 1.01 equivalent) of triphenylsulfonium bromide in 432 g of chloroform was added, and the mixture was further stirred at room temperature for 1 hour. After confirming the completion of the reaction by ¹ H NMR, the layers were separated and the organic layer was washed with 300 g of water three times. The obtained organic layer was concentrated under reduced pressure to obtain 238 g of triphenylsulfonium 2,2-difluoro-3-methacryloyloxypentanoate (yield 81%, purity 80%).

[Physical properties of 2,2-difluoro-3-methacryloyloxypentanoic acid triphenylsulfonium]
¹ H NMR (measurement solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.67 (m, 15H; Ph group), 6.10 (s, 1H; = CH ₂ ), 5.53 (m _{, 1H; CH-O),} 5.47 (s, 1H; = CH 2), 1.86 (s, 3H; CH 3 -C), 1.84 (m, 1H; the _CH-CH 2 CH _{3 CH 2), 1.71 (m,} 1H; CH-CH CH 2) a _{2 CH 3, 0.83 (t,} J = 7.6 Hz, 3H; CH 3 of _CH-CH 2 CH _3).
19F NMR (measurement solvent: deuterated chloroform, reference material: trichlorofluoromethane); δ = −111.52 (d, J = 244 Hz, 1F), −118.07 (d, J = 244 Hz, 1F).

[Reference Example 1] Polymer Synthesis Example 1
In a 200 mL dropping cylinder under nitrogen atmosphere, 13.74 g of 4-hydroquinone monomethacrylate, 3.00 g of acenaphthylene, 12.47 g of 4-amyloxystyrene, 2,2-difluoro-3-methacryloyloxypentanoic acid prepared in Reference Example 1 A solution in which 0.79 g of triphenylsulfonium, 3.02 g of dimethyl-2,2′-azobis- (2-methylpropionate) (trade name V601, manufactured by Wako Pure Chemical Industries, Ltd.) and 42 g of methyl ethyl ketone as a solvent were added. Prepared. Further, 28 g of methyl ethyl ketone was added to another 200 mL polymerization flask under a nitrogen atmosphere, and the previously prepared solution was added dropwise over 4 hours in a state heated to 80 ° C. After completion of the dropping, stirring was continued for 4 hours while maintaining the polymerization temperature at 80 ° C., and then cooled to room temperature. The obtained polymerization solution was dropped into 600 g of hexane, and the precipitated copolymer was separated by filtration. The copolymer separated by filtration was washed twice with 150 g of hexane, and then a solution prepared by dissolving in 70 g of methyl ethyl ketone was passed through a 0.02 μm nylon filter and dropped into 600 g of hexane, and the precipitated copolymer was filtered. Separated. The copolymer separated by filtration was washed twice with 150 g of hexane and dried to obtain 28 g of a white copolymer (Polymer 1, P-01). Molecular weight Mw = 3530 (Mw / Mn = 1.40)).

Reference Example 2 Synthesis of Comparative Polymer Polymer-M (PM) having the following structure was prepared by a known method. Molecular weight Mw = 3940 (Mw / Mn = 1.45).

[Reference Examples 3 to 4, Reference Comparative Example 1] Preparation of Positive Resist Material Polymer 1 and Comparative Polymer-M synthesized above, acid generator (PAG-A) represented by the following formula, basic compound (Base) 1) was dissolved in an organic solvent with the composition shown in Table 1 to prepare a resist material, and further filtered through a 0.02 μm size nylon or UPE filter to prepare positive resist material solutions.

  The organic solvents in Table 1 are PGMEA (propylene glycol monomethyl ether acetate), EL (ethyl lactate), and PGME (propylene glycol monomethyl ether).

  In addition, each solution contains 3-methyl-3- (2,2,2-trifluoroethoxymethyl) oxetane / tetrahydrofuran / 2,2-dimethyl-1,3-propanediol copolymer (Omnova) as a surfactant. (Manufactured by Kogyo Co., Ltd.) (the structural formula is shown below) was added in an amount of 0.1 part by mass per 100 parts by mass of the polymer.

[Reference Example 5] Electron Beam Drawing Evaluation The positive resist material (Reference Examples 1 and 2, Reference Comparative Example 1) prepared above is ACT-M (manufactured by Tokyo Electron Ltd.) and the outermost surface of 152 mm square is a chromium oxynitride film. Was spin-coated on a mask blank, and pre-baked on a hot plate at 110 ° C. for 600 seconds to produce a 60 nm resist film. The film thickness of the obtained resist film was measured using an optical measuring device Nanospec (manufactured by Nanometrics). The measurement was performed at 81 points in the surface of the blank substrate excluding the outer edge portion from the blank outer periphery to the 10 mm inner side, and the film thickness average value and the film thickness range were calculated. Further, exposure was performed using an electron beam exposure apparatus (manufactured by New Flare Technology Co., Ltd., EBM-5000 plus, acceleration voltage 50 keV), baking was performed at 110 ° C. for 600 seconds (PEB: post exposure bake), and 2.38% by mass. When developing with an aqueous solution of tetramethylammonium hydroxide, a positive pattern could be obtained. Furthermore, the obtained resist pattern was evaluated as follows.

The prepared wafer with a pattern is observed with an over-the-air SEM (scanning electron microscope), and the exposure amount for resolving the 200 nm 1: 1 line and space (LS) with 1: 1 is the optimum exposure amount (uC / cm ² ). The minimum dimension at the exposure amount for resolving 200 nm line and space at 1: 1 was defined as the critical resolution, and the edge roughness (LER) of 100 nm LS was measured by SEM. Regarding the pattern shape, it was visually determined whether or not the cross-sectional shape was rectangular. Table 2 shows the evaluation results of the resist material according to the monomer of the present invention and the comparative resist material in EB drawing.

  As shown in Table 2 above, it was shown that the resist material according to the monomer of the present invention was superior in resolution and line edge roughness as compared with the resist material listed in Reference Comparative Example 1. Therefore, by using the monomer of the present invention, a copolymer for preparing a chemically amplified resist material suitable as a fine pattern forming material and a mask pattern forming material by electron beam lithography especially for VLSI manufacturing is synthesized. I understood that I could do it.

  It is useful as a monomer for synthesizing copolymers with photoacid generator function for preparing chemically amplified resist materials suitable as fine pattern forming materials and mask pattern forming materials by high energy beam lithography for VLSI manufacturing. .

Claims (4)

Fluorine-containing unsaturated carboxylic acid onium salt represented by the following general formula (1).

(Wherein R ¹ represents an acryloyloxy group or a methacryloyloxy group ,
R ² represents a fluorine atom or a fluorine-containing alkyl group,
W ¹ is the following formula:

[Wherein, O and C represent an oxygen atom and a carbon atom adjacent to the substituted methylene group. ]
Any one of the substituted methylene groups represented by
Q ⁺ represents a sulfonium cation emission represented by the following general formula (a) or the following general formula (b).

In the general formula ^(a), R 3, ^{R 4} and ^{R 5} indicates a substitution or unsubstituted aryl group having 6 to 18 carbon atoms independently of one another, one of ^R 3, ^{R 4} and ^{R 5} Any two or more may be bonded to each other to form a ring together with the sulfur atom in the formula.

In the general formula (b), R ⁶ represents a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. m represents an integer of 1 to 5, and n represents 0 (zero) or 1. The substituent for R ⁶ may contain a carbonyl group, a hydroxyl group, an ester, a lactone, an amino group, an amide group, or an ether-bonded oxygen atom. ) Fluorine-containing unsaturated carboxylic acid onium salt represented by the following general formula (1).

(Wherein R ¹ Represents an acryloyloxy group or a methacryloyloxy group,
R ² Represents a fluorine atom or a fluorine-containing alkyl group,
W ¹ Is the following formula:

[Wherein, O and C represent an oxygen atom and a carbon atom adjacent to the substituted methylene group. ]
Any one of the substituted methylene groups represented by ⁺ Represents a triphenylsulfonium cation. ) The fluorine-containing unsaturated carboxylic acid onium salt according to claim 1 or ^{2, wherein} R ² is a fluorine atom. 2,2-difluoro-3-methacryloyloxypentanoic acid triphenylsulfonium represented by the following formula: