JP7233948B2 - Salt, acid generator, resist composition and method for producing resist pattern - Google Patents

Description

The present invention relates to a salt, an acid generator, a resist composition, and a method for producing a resist pattern.

特許文献２には、下記式で表される塩を酸発生剤として含有するレジスト組成物が記載されている。

Patent Document 1 describes a resist composition containing a salt represented by the following formula as an acid generator.

Patent Document 2 describes a resist composition containing a salt represented by the following formula as an acid generator.

JP 2013-035829 A JP 2012-236816 A

An object of the present invention is to provide a salt capable of producing a resist pattern with better CD uniformity (CDU) than a resist pattern formed from a resist composition containing the above salt.

［式（Ｉ）中、
Ｒ^１は、置換基を有してもよい炭素数６～１８の芳香族炭化水素基を表す。
Ｘ^Ａは、硫黄原子又はヨウ素原子を表す。
Ｘ^１は、置換基を有してもよい炭素数１～３６の脂肪族炭化水素基を表し、該脂肪族炭化水素基に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていてもよい。ただし、該脂肪族炭化水素基に含まれる水素原子の少なくとも１つは、式（ＩＡ）で表される基で置換されている。
Ｘ^Ａが硫黄原子の時、ｎは１～３のいずれかの整数を表し、ｍは０～２のいずれかの整数を表す。但し、ｍ＋ｎ＝３である。
Ｘ^Ａがヨウ素原子の時、ｎは１又は２を表し、ｍは０又は１を表す。但し、ｍ＋ｎ＝２である。
ｍ及びｎが２以上である場合、複数のＲ^１、Ｘ^１は、同じでも異なっていてもよい。
ｎが２以上の場合、式（ＩＡ）で表される基は、少なくとも１つがＸ^１に置換していれば、残りのＸ^１が無置換でもよい。
Ａ^－は、有機アニオンを表す。］

［式（ＩＡ）中、
Ｌ^２は、置換基を有していてもよい炭素数１～３６の炭化水素基を表す。
Ｒ^Ａは、炭素数１～１２の飽和炭化水素基を表す。
ｕ１は、０～２の整数を表し、ｕ１が２である場合、複数のＲ ^Ａ は同一であるか、相異なる。
ｓ１は、１又は２を表す。
ｔ１は、０又は１を表す。但し、ｓ１とｔ１との和は、１又は２である。
＊は、結合手を表す。］
［２］Ｘ^１が、置換基を有してもよい炭素数１～６の鎖式炭化水素基（該鎖式炭化水素基に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていてもよい。ただし、該鎖式炭化水素基に含まれる水素原子の少なくとも１つは、式（ＩＡ）で表される基で置換されている。）である［１］に記載の塩。
［３］Ｒ^１が、置換基を有していてもよいフェニル基である［１］又は［２］記載の塩。
［４］ｍが、１である［１］～［３］のいずれかに記載の塩。
［５］Ａ^－は、式（Ｉ－Ａ）で表されるスルホン酸アニオンである［１］～［４］のいずれかに記載の塩。

［式（Ｉ－Ａ）中、
Ｑ^１及びＱ^２は、それぞれ独立に、フッ素原子又は炭素数１～６のペルフルオロアルキル基を表す。
Ｌ^１は、炭素数１～２４の飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基で置換されていてもよい。
Ｙ^１は、置換基を有していてもよいメチル基又は置換基を有していてもよい炭素数３～１８の脂環式炭化水素基を表し、該脂環式炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－ＳＯ_２－又は－ＣＯ－に置き換わっていてもよい。］
［６］［１］～［５］のいずれかに記載の塩を含有する酸発生剤。
［７］［６］に記載の酸発生剤と酸不安定基を有する樹脂とを含有するレジスト組成物。
［８］さらに、酸発生剤から発生する酸よりも酸性度の弱い酸を発生する塩を含有する［７］に記載のレジスト組成物。
［９］（１）［７］又は［８］に記載のレジスト組成物を基板上に塗布する工程、
（２）塗布後の組成物を乾燥させて組成物層を形成する工程、
（３）組成物層に露光する工程、
（４）露光後の組成物層を加熱する工程、及び
（５）加熱後の組成物層を現像する工程を含むレジストパターンの製造方法。 The present invention includes the following inventions.
[1] A salt represented by formula (I).

[in the formula (I),
R ¹ represents an aromatic hydrocarbon group having 6 to 18 carbon atoms which may have a substituent.
^XA represents a sulfur atom or an iodine atom.
X ¹ represents an optionally substituted aliphatic hydrocarbon group having 1 to 36 carbon atoms, and —CH ₂ — contained in the aliphatic hydrocarbon group is —O—, —S—, — CO- or -SO ₂ - may be substituted. However, at least one hydrogen atom contained in the aliphatic hydrocarbon group is substituted with a group represented by formula (IA).
X When ^A is a sulfur atom, n represents an integer of 1-3 and m represents an integer of 0-2. However, m+n=3.
X When ^A is an iodine atom, n represents 1 or 2 and m represents 0 or 1. However, m+n=2.
When m and n are 2 or more, a plurality of R ¹ and X ¹ may be the same or different.
When n is 2 or more, in the group represented by formula (IA), as long as at least one X 1 is substituted on X ¹ , the remaining X ¹ may be unsubstituted.
A ⁻ represents an organic anion. ]

[In the formula (IA),
L ² represents an optionally substituted hydrocarbon group having 1 to 36 carbon atoms.
R ^A represents a saturated hydrocarbon group having 1 to 12 carbon atoms.
u1 represents an integer of 0 to 2, and when u1 is 2, multiple RAs are ^the same or different.
s1 represents 1 or 2;
t1 represents 0 or 1; However, the sum of s1 and t1 is 1 or 2.
* represents a bond. ]
[2] X ¹ is an optionally substituted chain hydrocarbon group having 1 to 6 carbon atoms (-CH ₂ - contained in the chain hydrocarbon group is -O-, -S-, —CO— or —SO ₂ —, provided that at least one hydrogen atom contained in the chain hydrocarbon group is substituted with a group represented by formula (IA).) The salt according to [1].
[3] The salt according to [1] or [2], wherein R ¹ is an optionally substituted phenyl group.
[4] The salt according to any one of [1] to [3], wherein m is 1.
[5] The salt according to any one of [1] to [4], wherein A ^- is a sulfonate anion represented by formula (IA).

[In the formula (IA),
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
L ¹ represents a saturated hydrocarbon group having 1 to 24 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O— or —CO—; A hydrogen atom contained in may be substituted with a fluorine atom or a hydroxy group.
Y ¹ represents an optionally substituted methyl group or an optionally substituted alicyclic hydrocarbon group having 3 to 18 carbon atoms, and is included in the alicyclic hydrocarbon group -CH ₂ - may be replaced with -O-, -SO ₂ - or -CO-. ]
[6] An acid generator containing the salt according to any one of [1] to [5].
[7] A resist composition containing the acid generator of [6] and a resin having an acid-labile group.
[8] The resist composition of [7], further comprising a salt that generates an acid weaker in acidity than the acid generated from the acid generator.
[9] (1) a step of applying the resist composition according to [7] or [8] onto a substrate;
(2) a step of drying the applied composition to form a composition layer;
(3) exposing the composition layer;
(4) A process of heating the composition layer after exposure, and (5) a process of developing the composition layer after heating.

To provide a salt or the like capable of producing a resist pattern with good CD uniformity (CDU).

As used herein, "(meth)acrylic monomer" means at least one monomer having a structure of "CH ₂ =CH-CO-" or "CH ₂ =C(CH ₃ )-CO-". do. Similarly, "(meth)acrylate" and "(meth)acrylic acid" mean "at least one of acrylate and methacrylate" and "at least one of acrylic acid and methacrylic acid", respectively. In addition, among the groups described in this specification, any group that can have both a linear structure and a branched structure may be used. Where stereoisomers exist, all stereoisomers are included.
As used herein, "the solid content of the resist composition" means the total amount of components excluding the solvent (E) described below from the total amount of the resist composition.

<Salt Represented by Formula (I)>
The salt of the present invention is a salt represented by formula (I) (hereinafter sometimes referred to as salt (I)).
The aromatic hydrocarbon group for R ¹ includes aryl groups such as a phenyl group, naphthyl group, anthryl group, biphenyl group, phenanthryl group, and fluorenyl group, preferably a phenyl group, a naphthyl group and an anthryl group, and a phenyl group and A naphthyl group is more preferred, and a phenyl group is even more preferred.
Substituents possessed by the aromatic hydrocarbon group of R ¹ include an alkyl group having 1 to 12 carbon atoms (-CH ₂ - contained in the alkyl group may be replaced with -O- or -CO- ), an alicyclic hydrocarbon group having 3 to 12 carbon atoms, a group represented by the formula (IA) described later, and a combination thereof.
A group in which —CH ₂ — contained in an alkyl group is replaced by —O— or —CO— includes a hydroxy group (a group in which —CH ₂ — contained in a methyl group is replaced by —O—), carboxy group (group in which —CH ₂ —CH ₂ — contained in an ethyl group is replaced with —O—CO—), alkoxy group having 1 to 12 carbon atoms (containing in an alkyl group having 2 to 13 carbon atoms, A group in which -O- is substituted for CH ₂ -), an alkoxycarbonyl group having 2 to 13 carbon atoms (the -CH ₂ -CH ₂ - contained in an alkyl group having 4 to 15 carbon atoms is -O-CO- a group substituted with ), an alkylcarbonyl group having 2 to 13 carbon atoms (a group in which —CH ₂ — contained in an alkyl group having 3 to 14 carbon atoms is replaced with —CO—), an alkyl group having 2 to 13 carbon atoms Includes carbonyloxy groups (groups in which --CH ₂ --CH ₂ -- contained in alkyl groups having 4 to 15 carbon atoms are replaced with --CO--O--).
Examples of alkyl groups having 1 to 12 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group and dodecyl group. .
Examples of alkoxy groups having 1 to 12 carbon atoms include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, and undecyloxy. group, dodecyloxy group, and the like.
An alkoxycarbonyl group having 2 to 13 carbon atoms, an alkylcarbonyl group having 2 to 13 carbon atoms and an alkylcarbonyloxy group having 2 to 13 carbon atoms are groups in which a carbonyl group or a carbonyloxy group is bonded to the alkyl group or alkoxy group described above. represents
The alkoxycarbonyl group having 2 to 13 carbon atoms includes methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group and the like, and the alkylcarbonyl group having 2 to 13 carbon atoms includes acetyl group, propionyl group, butyryl group and the like. Examples of the alkylcarbonyloxy group having 2 to 13 carbon atoms include acetyloxy group, propionyloxy group and butyryloxy group.
The alicyclic hydrocarbon group having 3 to 12 carbon atoms may be monocyclic, polycyclic or spirocyclic, and may be saturated or unsaturated. The alicyclic hydrocarbon group includes monocyclic cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclononyl, cyclodecyl, and cyclododecyl, norbornyl, and adamantyl. and polycyclic cycloalkyl groups such as
Among them, R1 is preferably substituted with one or more groups represented by formula (IA).
R ¹ is a phenyl group (the phenyl group is an alkyl group having 1 to 12 carbon atoms, a group obtained by combining an alkyl group having 1 to 12 carbon atoms and an alicyclic hydrocarbon group having 3 to 12 carbon atoms, and carbon It may have a group in which an alkyl group of numbers 1 to 12 and a group represented by formula (IA) are combined, and -CH ₂ - contained in the alkyl group is -O- or -CO- may be substituted) is preferred.

The aliphatic hydrocarbon group for X ¹ includes a linear or branched chain hydrocarbon group (e.g., alkyl group, alkanediyl group, alkenediyl group, alkynediyl group) and monocyclic or polycyclic alicyclic and the like, and groups in which two or more of these groups are combined may be used.

Alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group and decyl group. linear or branched alkyl groups such as , undecyl and dodecyl groups.
The alkanediyl groups include methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane- 1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group linear alkanediyl groups such as groups;
ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2,4-diyl group, 2-methylpropane- Branched alkanediyl groups such as 1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group and 2-methylbutane-1,4-diyl group can be mentioned.
Alkenediyl groups include ethenediyl, propenediyl, isopropenediyl, butenediyl, isobutenediyl, tert-butenediyl, pentenediyl, hexenediyl, heptenediyl, octynediyl, isooctynediyl, and nonenediyl groups. .
The alkynediyl group includes ethynediyl, propynediyl, isopropynediyl, butynediyl, isobutynediyl, tert-butynediyl, pentynediyl, hexynediyl, octynediyl, nonynediyl, and the like.
The monocyclic alicyclic hydrocarbon groups include cyclobutane-1,3-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,4-diyl group, cyclohexene-3,6-diyl group, and monocyclic cycloalkanediyl groups such as cyclooctane-1,5-diyl group.
Polycyclic alicyclic hydrocarbon groups include norbornane-1,4-diyl group, norbornane-2,5-diyl group, 5-norbornene-2,3-diyl group and adamantane-1,5-diyl group , adamantane-2,6-diyl group and other polycyclic cycloalkanediyl groups.
Examples of the hydrocarbon group in which two or more types are combined include a group in which a chain hydrocarbon group (e.g., an alkanediyl group, etc.) and an alicyclic hydrocarbon group are combined, and the like, - alicyclic hydrocarbon group group - Chain hydrocarbon group - (eg, - cycloalkanediyl group - alkanediyl group - etc.), - Chain hydrocarbon group - alicyclic hydrocarbon group - (eg, - alkanediyl group - cycloalkanediyl group - etc.), - chain hydrocarbon group - alicyclic hydrocarbon group - chain hydrocarbon group - (eg - alkanediyl group - cycloalkanediyl group - alkanediyl group - etc.) and the like.

A halogen atom, a cyano group, etc. are mentioned as a substituent which the aliphatic hydrocarbon group of ^X1 has.
Halogen atoms include fluorine, chlorine, bromine and iodine atoms.
The aliphatic hydrocarbon group having 1 to 36 carbon atoms represented by X ¹ may have one substituent or multiple substituents.

-CH ₂ - contained in the hydrocarbon group having 1 to 36 carbon atoms of X ¹ may be replaced with -O-, -S-, -CO- or -SO ₂ -.
When the hydrocarbon group having 1 to 36 carbon atoms of X ¹ has a substituent, the carbon number of the hydrocarbon group does not include the carbon number of the substituent. In addition, when —CH ₂ — contained in a hydrocarbon group is replaced with —O—, —S—, —CO— or —SO ₂ —, the number of carbon atoms before replacement is the number of carbon atoms in the hydrocarbon group.

X ¹ is a chain hydrocarbon group having 1 to 8 carbon atoms (eg, an alkyl group, an alkanediyl group, etc.) (-CH ₂ - contained in the chain hydrocarbon group may be -O- or -CO- may be substituted) or a chain hydrocarbon group having 1 to 6 carbon atoms (eg, an alkanediyl group) (-CH ₂ - contained in the chain hydrocarbon group may be substituted with -O- or -CO- may be substituted) and an alicyclic hydrocarbon group having 3 to 18 carbon atoms (-CH ₂ - contained in the alicyclic hydrocarbon group is -O-, -S-, -CO- or -SO ₂ - may be substituted), and a chain hydrocarbon group having 1 to 8 carbon atoms (e.g., an alkyl group, an alkanediyl group, etc.) (the chain hydrocarbon group -CH ₂ - contained is more preferably a chain hydrocarbon group having 1 to 6 carbon atoms (eg, an alkyl group, an alkanediyl group, etc., which may be replaced by -O- or -CO-). ) (-CH ₂ - contained in the chain hydrocarbon group may be replaced with -O- or -CO-).

The aliphatic hydrocarbon group contained in X ¹ has at least one group represented by formula (IA), preferably two.

Examples of hydrocarbon groups having 1 to 36 carbon atoms for L ² include aliphatic hydrocarbon groups (alkanediyl groups, alkenediyl groups, alkynediyl groups and monocyclic or polycyclic alicyclic hydrocarbon groups), aromatic hydrocarbon groups, A hydrogen group and the like may be mentioned, and a divalent hydrocarbon group in which two or more of these groups are combined may be used.

The alkanediyl groups include methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane- 1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group linear alkanediyl groups such as groups;
ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2,4-diyl group, 2-methylpropane- Branched alkanediyl groups such as 1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group and 2-methylbutane-1,4-diyl group can be mentioned.
Alkenediyl groups include ethenediyl, propenediyl, isopropenediyl, butenediyl, isobutenediyl, tert-butenediyl, pentenediyl, hexenediyl, heptenediyl, octynediyl, isooctynediyl, and nonenediyl groups. .
The alkynediyl group includes ethynediyl, propynediyl, isopropynediyl, butynediyl, isobutynediyl, tert-butynediyl, pentynediyl, hexynediyl, octynediyl, nonynediyl, and the like.
The monocyclic alicyclic hydrocarbon groups include cyclobutane-1,3-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,4-diyl group, cyclohexene-3,6-diyl group, monocyclic cycloalkanediyl groups such as cyclooctane-1,5-diyl groups;
Polycyclic alicyclic hydrocarbon groups include norbornane-1,4-diyl group, norbornane-2,5-diyl group, 5-norbornene-2,3-diyl group and adamantane-1,5-diyl group , adamantane-2,6-diyl group and other polycyclic cycloalkanediyl groups.
The divalent aromatic hydrocarbon group includes a phenylene group, naphthylene group, anthrylene group, biphenylene group, phenanthrylene group and the like.
Examples of hydrocarbon groups in which two or more types are combined include a group in which an alkanediyl group and an alicyclic hydrocarbon group and/or an aromatic hydrocarbon group are combined, and the like, -cycloalkanediyl group-alkanediyl group- , -alkanediyl group-cycloalkanediyl group-, -alkanediyl group-cycloalkanediyl group-alkanediyl group-, -alkanediyl group-aromatic hydrocarbon group-, -aromatic hydrocarbon group-alkanediyl group- etc.

Examples of substituents possessed by the hydrocarbon group of L ² include a halogen atom, a cyano group, a hydroxy group, a carboxy group, an alkoxy group having 1 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 13 carbon atoms, and an alkoxycarbonyl group having 2 to 13 carbon atoms. Examples include an alkylcarbonyl group, an alkylcarbonyloxy group having 2 to 13 carbon atoms, an alkoxycarbonyl group having 2 to 13 carbon atoms, an alkylcarbonyl group having 2 to 13 carbon atoms, an alkylcarbonyloxy group having 2 to 13 carbon atoms, and the like.
Examples of the halogen atom include the same as those exemplified for the substituent of the aliphatic hydrocarbon group of ^X1 .
an alkoxy group having 1 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 13 carbon atoms,
Examples of the alkoxycarbonyl group having 2 to 13 carbon atoms are the same as those exemplified for the substituent of the aromatic hydrocarbon group for R ¹ .
The divalent hydrocarbon group having 1 to 36 carbon atoms represented by L ² may have one or more substituents.

L ² is preferably an alkanediyl group having 1 to 6 carbon atoms, more preferably an alkanediyl group having 1 to 3 carbon atoms, and even more preferably a methylene group.

s1 is preferably 1, t1 is preferably 1, and the sum of s1 and t1 is preferably 2.
The group represented by formula (IA) is preferably a group represented by the following.

Ｒ^Ａの飽和炭化水素基としては、アルキル基、脂環式炭化水素基及びこれらの２種以上の組み合わせが挙げられる。
Ｒ^Ａのアルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔｅｒｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基、ノニル基等のアルキル基が挙げられる。アルキル基の炭素数は、好ましくは１～９であり、より好ましくは１～４である。
脂環式炭化水素基は、単環式、多環式及びスピロ環のいずれでもよい。脂環式炭化水素基としては、シクロプロピル基、シクロブチル基、シクロペンチル基、シクロへキシル基、シクロオクチル基、シクロノニル基、シクロデシル基、シクロドデシル基等の単環式シクロアルキル基、ノルボルニル基、アダマンチル基等の多環式シクロアルキル基が挙げられる。
組み合わせた基は、上述したアルキル基と脂環式炭化水素基とを１つずつ組み合わせたものでも、いずれかを２以上又は双方を２以上組み合わせた基でもよい。 In the group represented by formula (IA), the group in which u1 is 1 and ^RA is bonded to the carbon atom adjacent to ^L2 is represented by the following formula.

Saturated hydrocarbon groups for ^RA include alkyl groups, alicyclic hydrocarbon groups, and combinations of two or more thereof.
The alkyl group of ^RA includes alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, octyl group and nonyl group. The number of carbon atoms in the alkyl group is preferably 1-9, more preferably 1-4.
Alicyclic hydrocarbon groups may be monocyclic, polycyclic or spirocyclic. The alicyclic hydrocarbon group includes monocyclic cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclononyl, cyclodecyl, and cyclododecyl, norbornyl, and adamantyl. and polycyclic cycloalkyl groups such as
The combined group may be a combination of one each of the alkyl group and the alicyclic hydrocarbon group described above, or a combination of two or more of either or two or more of both.

Specific examples of cations constituting salt (I) include cations represented by the following formulas (Ic-1) to (Ic-27).

Cation (I) is preferably a cation represented by formula (Ic-1) ~ formula (Ic-12), formula (Ic-16) ~ formula (Ic-23), formula (Ic-1) ~ Formula (Ic-3), Formula (Ic-16) ~ Formula (Ic-19), Formula (Ic-21), Formula (Ic- 25) to the cations represented by formulas (Ic-27) are more preferred.

［式（Ｉ－Ａ）中、
Ｑ^１及びＱ^２は、それぞれ独立に、フッ素原子又は炭素数１～６のペルフルオロアルキル基を表す。
Ｌ^１は、炭素数１～２４の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基で置換されていてもよい。
Ｙ^１は、置換基を有していてもよいメチル基又は置換基を有していてもよい炭素数３～１８の脂環式炭化水素基を表し、該脂環式炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－ＳＯ_２－又は－ＣＯ－に置き換わっていてもよい。］
式（Ｉ－Ａ）において、飽和炭化水素基、脂環式炭化水素基に含まれる－ＣＨ_２－が－Ｏ－、－Ｃ（＝Ｏ）－又は－ＳＯ_２－に置き換わっている場合、置き換わる前の炭素数をそれぞれ該飽和炭化水素基、該脂環式炭化水素基の炭素数とする。 <Organic Anion Constituting Salt (I)>
Organic anions (A ⁻ ) constituting salt (I) include sulfonate anions, sulfonylimide anions, sulfonylmethide anions and carboxylate anions. Among these, sulfonate anions are preferred, and sulfonate anions represented by formula (IA) are more preferred.

[In the formula (IA),
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
L ¹ represents a divalent saturated hydrocarbon group having 1 to 24 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O— or —CO—, and the saturated A hydrogen atom contained in the hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
Y ¹ represents an optionally substituted methyl group or an optionally substituted alicyclic hydrocarbon group having 3 to 18 carbon atoms, and is included in the alicyclic hydrocarbon group -CH ₂ - may be replaced with -O-, -SO ₂ - or -CO-. ]
In formula (IA), when —CH ₂ — contained in a saturated hydrocarbon group or alicyclic hydrocarbon group is replaced with —O—, —C(=O)— or —SO ₂ —, it is replaced Let the number of carbon atoms in front be the number of carbon atoms of the saturated hydrocarbon group and the alicyclic hydrocarbon group, respectively.

The perfluoroalkyl groups represented by Q ¹ and Q ² include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group and A perfluorohexyl group and the like can be mentioned.
Q ¹ and Q ² are each independently preferably a fluorine atom or a trifluoromethyl group, more preferably both a fluorine atom.

The divalent saturated hydrocarbon group for L ¹ includes a linear alkanediyl group, a branched alkanediyl group, a monocyclic or polycyclic bivalent alicyclic saturated hydrocarbon group, and these A group formed by combining two or more of the groups may also be used.
Specifically, methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1 ,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group , tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group and heptadecane-1,17-diyl group. alkanediyl group;
ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2,4-diyl group, 2-methylpropane- Branched alkanediyl groups such as 1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group;
monocyclic 2 which is a cycloalkanediyl group such as cyclobutane-1,3-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,4-diyl group, cyclooctane-1,5-diyl group; alicyclic saturated hydrocarbon group;
Polycyclic divalent alicyclic saturated hydrocarbons such as norbornane-1,4-diyl group, norbornane-2,5-diyl group, adamantane-1,5-diyl group, and adamantane-2,6-diyl group and the like.

Groups in which —CH ₂ — contained in the divalent saturated hydrocarbon group represented by L ¹ is replaced with —O— or —CO— include, for example, formulas (b1-1) to (b1-3) A group represented by any one of is mentioned. In addition, in the groups represented by formulas (b1-1) to (b1-3) and the groups represented by formulas (b1-4) to (b1-11) which are specific examples thereof, * and * * represents the binding site and * represents the bond with ^-Y1 .

［式（ｂ１－１）中、
Ｌ^ｂ２は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^ｂ３は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよく、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
ただし、Ｌ^ｂ２とＬ^ｂ３との炭素数合計は、２２以下である。
式（ｂ１－２）中、
Ｌ^ｂ４は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^ｂ５は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよく、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
ただし、Ｌ^ｂ４とＬ^ｂ５との炭素数合計は、２２以下である。
式（ｂ１－３）中、
Ｌ^ｂ６は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
Ｌ^ｂ７は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよく、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
ただし、Ｌ^ｂ６とＬ^ｂ７との炭素数合計は、２３以下である。］

[In formula (b1-1),
L ^b2 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b3 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and the saturated —CH ₂ — contained in the hydrocarbon group may be replaced with —O— or —CO—.
However, the total number of carbon atoms of L ^b2 and L ^b3 is 22 or less.
In formula (b1-2),
L ^b4 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b5 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and the saturated —CH ₂ — contained in the hydrocarbon group may be replaced with —O— or —CO—.
However, the total number of carbon atoms of L ^b4 and L ^b5 is 22 or less.
In formula (b1-3),
L ^b6 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
L ^b7 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and the saturated —CH ₂ — contained in the hydrocarbon group may be replaced with —O— or —CO—.
However, the total number of carbon atoms of L ^b6 and L ^b7 is 23 or less. ]

In the groups represented by formulas (b1-1) to (b1-3), when —CH ₂ — contained in the saturated hydrocarbon group is replaced with —O— or —CO—, carbon before replacement Let the number be the number of carbon atoms of the saturated hydrocarbon group.
As the divalent saturated hydrocarbon group, the same divalent saturated hydrocarbon group as L ^b1 can be mentioned.

L ^b2 is preferably a single bond.
L ^b3 is preferably a divalent saturated hydrocarbon group having 1 to 4 carbon atoms.
L ^b4 is preferably a divalent saturated hydrocarbon group having 1 to 8 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b5 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b6 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 4 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b7 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group; —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O— or —CO—.

The group in which —CH ₂ — contained in the divalent saturated hydrocarbon group represented by L ^b1 is replaced with —O— or —CO— is represented by formula (b1-1) or formula (b1-3). are preferred.

［式（ｂ１－４）中、
Ｌ^ｂ８は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
式（ｂ１－５）中、
Ｌ^ｂ９は、炭素数１～２０の２価の飽和炭化水素基を表し、該２価の飽和炭化水素基に含まれる－ＣＨ_２－は－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｌ^ｂ１０は、単結合又は炭素数１～１９の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ９及びＬ^ｂ１０の合計炭素数は２０以下である。
式（ｂ１－６）中、
Ｌ^ｂ１１は、炭素数１～２１の２価の飽和炭化水素基を表す。
Ｌ^ｂ１２は、単結合又は炭素数１～２０の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ１１及びＬ^ｂ１２の合計炭素数は２１以下である。
式（ｂ１－７）中、
Ｌ^ｂ１３は、炭素数１～１９の２価の飽和炭化水素基を表す。
Ｌ^ｂ１４は、単結合又は炭素数１～１８の２価の飽和炭化水素基を表し、該２価の飽和炭化水素基に含まれる－ＣＨ_２－は－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｌ^ｂ１５は、単結合又は炭素数１～１８の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ１３～Ｌ^ｂ１５の合計炭素数は１９以下である。
式（ｂ１－８）中、
Ｌ^ｂ１６は、炭素数１～１８の２価の飽和炭化水素基を表し、該２価の飽和炭化水素基に含まれる－ＣＨ_２－は－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｌ^ｂ１７は、炭素数１～１８の２価の飽和炭化水素基を表す。
Ｌ^ｂ１８は、単結合又は炭素数１～１７の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ１６～Ｌ^ｂ１８の合計炭素数は１９以下である。］ Examples of the group represented by formula (b1-1) include groups represented by formulas (b1-4) to (b1-8).

[In formula (b1-4),
L ^b8 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
In formula (b1-5),
L ^b9 represents a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and —CH ₂ — contained in the divalent saturated hydrocarbon group may be replaced with —O— or —CO—.
L ^b10 represents a single bond or a divalent saturated hydrocarbon group having 1 to 19 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
However, the total carbon number of L ^b9 and L ^b10 is 20 or less.
In formula (b1-6),
L ^b11 represents a divalent saturated hydrocarbon group having 1 to 21 carbon atoms.
L ^b12 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
However, the total carbon number of L ^b11 and L ^b12 is 21 or less.
In formula (b1-7),
L ^b13 represents a divalent saturated hydrocarbon group having 1 to 19 carbon atoms.
L ^b14 represents a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and —CH ₂ — contained in the divalent saturated hydrocarbon group is replaced with —O— or —CO— good too.
L ^b15 represents a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
However, the total carbon number of L ^b13 to L ^b15 is 19 or less.
In formula (b1-8),
L ^b16 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and —CH ₂ — contained in the divalent saturated hydrocarbon group may be replaced with —O— or —CO—.
L ^b17 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms.
L ^b18 represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
However, the total carbon number of L ^b16 to L ^b18 is 19 or less. ]

L ^b8 is preferably a divalent saturated hydrocarbon group having 1 to 4 carbon atoms.
L ^b9 is preferably a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b10 is preferably a single bond or a C 1-19 divalent saturated hydrocarbon group, more preferably a single bond or a C 1-8 divalent saturated hydrocarbon group.
L ^b11 is preferably a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b12 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b13 is preferably a divalent saturated hydrocarbon group having 1 to 12 carbon atoms.
L ^b14 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 6 carbon atoms.
L ^b15 is preferably a single bond or a C 1-18 divalent saturated hydrocarbon group, more preferably a single bond or a C 1-8 divalent saturated hydrocarbon group.
L ^b16 is preferably a divalent saturated hydrocarbon group having 1 to 12 carbon atoms.
L ^b17 is preferably a divalent saturated hydrocarbon group having 1 to 6 carbon atoms.
L ^b18 is preferably a single bond or a C 1-17 divalent saturated hydrocarbon group, more preferably a single bond or a C 1-4 divalent saturated hydrocarbon group.

式（ｂ１－９）中、
Ｌ^b19は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^b20は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子、ヒドロキシ基又はアルキルカルボニルオキシ基に置換されていてもよい。該アルキルカルボニルオキシ基に含まれる－ＣＨ₂－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該アルキルカルボニルオキシ基に含まれる水素原子は、ヒドロキシ基に置換されていてもよい。
ただし、Ｌ^b19及びＬ^b20の合計炭素数は２３以下である。
式（ｂ１－１０）中、
Ｌ^b21は、単結合又は炭素数１～２１の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^b22は、単結合又は炭素数１～２１の２価の飽和炭化水素基を表す。
Ｌ^b23は、単結合又は炭素数１～２１の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子、ヒドロキシ基又はアルキルカルボニルオキシ基に置換されていてもよい。該アルキルカルボニルオキシ基に含まれる－ＣＨ₂－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該アルキルカルボニルオキシ基に含まれる水素原子は、ヒドロキシ基に置換されていてもよい。
ただし、Ｌ^b21、Ｌ^b22及びＬ^b23の合計炭素数は２１以下である。
式（ｂ１－１１）中、
Ｌ^b24は、単結合又は炭素数１～２０の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^b25は、炭素数１～２１の２価の飽和炭化水素基を表す。
Ｌ^b26は、単結合又は炭素数１～２０の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる水素原子は、フッ素原子、ヒドロキシ基又はアルキルカルボニルオキシ基に置換されていてもよい。該アルキルカルボニルオキシ基に含まれる－ＣＨ₂－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該アルキルカルボニルオキシ基に含まれる水素原子は、ヒドロキシ基に置換されていてもよい。
ただし、Ｌ^b24、Ｌ^b25及びＬ^b26の合計炭素数は２１以下である。 Examples of the group represented by formula (b1-3) include groups represented by formulas (b1-9) to (b1-11).

In formula (b1-9),
L ^b19 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b20 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group being substituted with a fluorine atom, a hydroxy group or an alkylcarbonyloxy group; good too. --CH ₂ -- contained in the alkylcarbonyloxy group may be replaced with --O-- or --CO--, and a hydrogen atom contained in the alkylcarbonyloxy group may be substituted with a hydroxy group.
However, the total carbon number of L ^b19 and L ^b20 is 23 or less.
In formula (b1-10),
L ^b21 represents a single bond or a divalent saturated hydrocarbon group having 1 to 21 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b22 represents a single bond or a divalent saturated hydrocarbon group having 1 to 21 carbon atoms.
L ^b23 represents a single bond or a divalent saturated hydrocarbon group having 1 to 21 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group is substituted with a fluorine atom, a hydroxy group or an alkylcarbonyloxy group; good too. --CH ₂ -- contained in the alkylcarbonyloxy group may be replaced with --O-- or --CO--, and a hydrogen atom contained in the alkylcarbonyloxy group may be substituted with a hydroxy group.
However, the total carbon number of L ^b21 , L ^b22 and L ^b23 is 21 or less.
In formula (b1-11),
L ^b24 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b25 represents a divalent saturated hydrocarbon group having 1 to 21 carbon atoms.
L ^b26 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group is substituted with a fluorine atom, a hydroxy group or an alkylcarbonyloxy group; good too. --CH ₂ -- contained in the alkylcarbonyloxy group may be replaced with --O-- or --CO--, and a hydrogen atom contained in the alkylcarbonyloxy group may be substituted with a hydroxy group.
However, the total carbon number of L ^b24 , L ^b25 and L ^b26 is 21 or less.

In addition, in the group represented by formula (b1-9) to the group represented by formula (b1-11), when the hydrogen atom contained in the saturated hydrocarbon group is substituted with an alkylcarbonyloxy group, it is substituted Let the previous carbon number be the carbon number of this saturated hydrocarbon group.

The alkylcarbonyloxy group includes an acetyloxy group, a propionyloxy group, a butyryloxy group, a cyclohexylcarbonyloxy group, an adamantylcarbonyloxy group and the like.

Examples of the group represented by formula (b1-4) include the following.

Examples of the group represented by formula (b1-5) include the following.

Examples of the group represented by formula (b1-6) include the following.

Examples of the group represented by formula (b1-7) include the following.

Examples of the group represented by formula (b1-8) include the following.

Examples of the group represented by formula (b1-2) include the following.

Examples of the group represented by formula (b1-9) include the following.

Examples of the group represented by formula (b1-10) include the following.

Examples of the group represented by formula (b1-11) include the following.

The alicyclic hydrocarbon group represented by Y ¹ includes groups represented by formulas (Y1) to (Y11) and formulas (Y36) to (Y38).
When —CH ₂ — contained in the alicyclic hydrocarbon group represented by Y ¹ is replaced with —O—, —S(O) ₂ — or —CO—, the number may be 1, or 2 or more. It's okay. Such groups include groups represented by formulas (Y12) to (Y35) and formulas (Y39) to (Y41).

The alicyclic hydrocarbon group represented by Y ¹ is preferably represented by formulas (Y1) to (Y20), formula (Y26), formula (Y27), formula (Y30), formula (Y31) and formula (Y39). ) to a group represented by any one of formula (Y41), more preferably formula (Y11), formula (Y15), formula (Y16), formula (Y20), formula (Y26), formula (Y27), Groups represented by formulas (Y30) to (Y31), formula (Y39) or formula (Y40), more preferably formula (Y11), formula (Y15), formula (Y20), formula (Y30), It is a group represented by formula (Y39) or formula (Y40).
When the alicyclic hydrocarbon group represented by Y ¹ is a spiro ring containing an oxygen atom such as formulas (Y28) to (Y35), formula (Y39) or formula (Y40), two oxygen The interatomic alkanediyl group preferably has one or more fluorine atoms. Further, among the alkanediyl groups contained in the ketal structure, the methylene group adjacent to the oxygen atom is preferably not substituted with a fluorine atom.

Examples of substituents of the methyl group represented by Y ¹ include a halogen atom, a hydroxy group, an alicyclic hydrocarbon group having 3 to 16 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, a glycidyloxy group, - (CH ₂ ) _ja —CO—O—R ^b1 group or —(CH ₂ ) _ja —O—CO—R ^b1 group (wherein R ^b1 is an alkyl group having 1 to 16 carbon atoms, represents an alicyclic hydrocarbon group or an aromatic hydrocarbon group having 6 to 18 carbon atoms or a group combining these.ja represents any integer of 0 to 4. Alkyl group having 1 to 16 carbon atoms , and —CH ₂ — contained in an alicyclic hydrocarbon group having 3 to 16 carbon atoms may be replaced with —O—, —S(O) ₂ — or —CO—.) and the like. .
Substituents for the alicyclic hydrocarbon group represented by Y ¹ include a halogen atom, a hydroxy group, an alkyl group having 1 to 12 carbon atoms which may be substituted with a hydroxy group, and an alicyclic ring having 3 to 16 carbon atoms. formula hydrocarbon group, alkoxy group having 1 to 12 carbon atoms, aromatic hydrocarbon group having 6 to 18 carbon atoms, aralkyl group having 7 to 21 carbon atoms, alkylcarbonyl group having 2 to 4 carbon atoms, glycidyloxy group, - (CH ₂ ) _ja —CO—O—R ^b1 group or —(CH ₂ ) _ja —O—CO—R ^b1 group (wherein R ^b1 is an alkyl group having 1 to 16 carbon atoms, represents an alicyclic hydrocarbon group or an aromatic hydrocarbon group having 6 to 18 carbon atoms or a group combining these.ja represents any integer of 0 to 4. Alkyl group having 1 to 16 carbon atoms , and —CH ₂ — contained in an alicyclic hydrocarbon group having 3 to 16 carbon atoms may be replaced with —O—, —S(O) ₂ — or —CO—.) and the like. .

Halogen atoms include fluorine, chlorine, bromine and iodine atoms.
Examples of alicyclic hydrocarbon groups include cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, and adamantyl groups.
The alicyclic hydrocarbon group may have a chain hydrocarbon group such as a methylcyclohexyl group and a dimethylcyclohexyl group.
Examples of aromatic hydrocarbon groups include aryl groups such as phenyl, biphenylyl, naphthyl, anthryl and phenanthryl groups.
The aromatic hydrocarbon group may have a chain hydrocarbon group or an alicyclic hydrocarbon group, and an aromatic hydrocarbon group having a chain hydrocarbon group having 1 to 18 carbon atoms (tolyl group, xylyl group, cumenyl group, mesityl group, p-ethylphenyl group, p-tert-butylphenyl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), and lipids having 3 to 18 carbon atoms. Examples thereof include aromatic hydrocarbon groups having a cyclic hydrocarbon group (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.).
Examples of alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group and nonyl. group, decyl group, undecyl group, dodecyl group and the like.
Alkyl groups substituted with a hydroxy group include hydroxyalkyl groups such as a hydroxymethyl group and a hydroxyethyl group.
Alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy and dodecyloxy groups.
Aralkyl groups include benzyl, phenethyl, phenylpropyl, naphthylmethyl and naphthylethyl groups.
Examples of alkylcarbonyl groups include acetyl group, propionyl group and butyryl group.

Examples of ^Y1 include the following.

Y ¹ is preferably an optionally substituted alicyclic hydrocarbon group having 3 to 18 carbon atoms, more preferably an optionally substituted adamantyl group, the alicyclic —CH ₂ — constituting a hydrocarbon group or adamantyl group may be replaced with —CO—, —S(O) ₂ — or —CO—. Y ¹ is more preferably an adamantyl group, a hydroxyadamantyl group, an oxoadamantyl group, or a group represented below.

Examples of the sulfonate anion in the salt represented by formula (I) include anions represented by formulas (B1-A-1) to (B1-A-55) [hereinafter referred to as "anion (B1 -A-1)”, etc. ] is preferable, formula (B1-A-1) ~ formula (B1-A-4), formula (B1-A-9), formula (B1-A-10), formula (B1-A-24) ~ formula (B1-A-33), represented by any of formulas (B1-A-36) to (B1-A-40), formulas (B1-A-47) to (B1-A-55) Anions are more preferred.

ここで、Ｒ^ｉ２～Ｒ^ｉ７は、それぞれ独立に、例えば、炭素数１～４のアルキル基、好ましくはメチル基又はエチル基である。Ｒ^ｉ８は、例えば、炭素数１～１２の脂肪族炭化水素基、好ましくは炭素数１～４のアルキル基、炭素数５～１２の脂環式炭化水素基又はこれらを組合せることにより形成される基、より好ましくはメチル基、エチル基、シクロヘキシル基又はアダマンチル基である。Ｌ^Ａ４１は、単結合又は炭素数１～４のアルカンジイル基である。
Ｑ^１及びＱ^２は、上記と同じ意味を表す。
式（Ｉ）で表される塩におけるスルホン酸アニオンとしては、具体的には、特開２０１０－２０４６４６号公報に記載されたアニオンが挙げられる。

Here, R ⁱ² to R ⁱ⁷ are each independently, for example, an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group. R ⁱ⁸ is, for example, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, an alicyclic hydrocarbon group having 5 to 12 carbon atoms, or a combination thereof. group, more preferably a methyl group, an ethyl group, a cyclohexyl group or an adamantyl group. L ^A41 is a single bond or an alkanediyl group having 1 to 4 carbon atoms.
Q ¹ and Q ² have the same meanings as above.
Specific examples of the sulfonate anion in the salt represented by formula (I) include anions described in JP-A-2010-204646.

Preferred examples of the sulfonate anion in the salt represented by formula (I) include anions represented by formulas (B1a-1) to (B1a-34).

Among them, formula (B1a-1) ~ formula (B1a-3) and formula (B1a-7) ~ formula (B1a-16), formula (B1a-18), formula (B1a-19), formula (B1a-22 ) to Formula (B1a-30) are preferred.

Salt (I) can be obtained by arbitrarily combining the above cations and organic anions. Specific examples of salt (I) are shown in Table 1.

In Table 1, salt (I-1) is the salt shown below.

Among them, salt (I) includes salt (I-2) to salt (I-5), salt (I-13) to salt (I-15), salt (I-17) to salt (I-19) , Salt (I-26) ~ Salt (I-29), Salt (I-37) ~ Salt (I-39), Salt (I-41) ~ Salt (I-43), Salt (I-50) ~ Salt (I-53), Salt (I-61) to Salt (I-63), Salt (I-65) to Salt (I-67), Salt (I-74) to Salt (I-77), Salt (I-85) to salt (I-87), salt (I-89) to salt (I-91), salt (I-98) to salt (I-101), salt (I-109) to salt ( I-111), salt (I-113) to salt (I-115), salt (I-122) to salt (I-125), salt (I-133) to salt (I-135), salt (I -137) to salt (I-139), salt (I-146) to salt (I-149), salt (I-157) to salt (I-159), salt (I-161) to salt (I- 163), salt (I-170) to salt (I-173), salt (I-181) to salt (I-183), salt (I-185) to salt (I-187), salt (I-194 ) to salt (I-197), salt (I-205) to salt (I-207), salt (I-209) to salt (I-211), salt (I-218) to salt (I-221) , Salt (I-229) ~ Salt (I-231), Salt (I-233) ~ Salt (I-235), Salt (I-242) ~ Salt (I-245), Salt (I-253) ~ Salt (I-255), salt (I-257) to salt (I-259) are preferred.

（式中、全ての符号は、それぞれ前記と同じ意味を表す。Ｘ⁰¹は、Ｘ¹から－（ＣＯ）ｎｎ－（式（ＩＡ）で表される基）を除いた基を表す。ｎｎは、Ｘ01末端が－ＣＯ－又は－ＳＯ_２－の時のみ０を表す。それ以外は、１である。）
この反応における溶剤としては、クロロホルム、アセトニトリル等が挙げられる。
反応温度は通常５℃～８０℃であり、反応時間は通常０．５時間～２４時間である。
式（Ｉ－ａ）で表される塩は、特開２０１３－０３５８２９号公報、特開２０１２－２３６８１６号公報に記載された方法を参考にして合成することができ、以下で表される塩などが挙げられる。

式（Ｉ－ｂ）で表される化合物としては、下記式で表される化合物等が挙げられ、市場より容易に入手することができる。

<Method for producing salt (I)>
Salt (I) is obtained by reacting a salt represented by formula (Ia) with carbonyldiimidazole in a solvent, and then further reacting with a compound represented by formula (Ib). can be manufactured.

(In the formula, all symbols have the same meanings as above. X ⁰¹ represents a group excluding -(CO)nn- (group represented by formula (IA)) from X ¹ nn is , X01 represents 0 only when the terminal is —CO— or —SO ₂ —, otherwise it is 1.)
Solvents in this reaction include chloroform, acetonitrile and the like.
The reaction temperature is usually 5° C. to 80° C., and the reaction time is usually 0.5 hour to 24 hours.
The salt represented by the formula (Ia) can be synthesized with reference to the methods described in JP-A-2013-035829 and JP-A-2012-236816, and the salts represented by the following, etc. are mentioned.

Examples of the compound represented by formula (Ib) include compounds represented by the following formula, etc., which are readily available on the market.

<Acid generator>
The acid generator of the present invention is an acid generator containing salt (I). One salt (I) may be contained, or two or more salts (I) may be contained in combination.
The acid generator of the present invention may contain an acid generator known in the resist field (hereinafter sometimes referred to as "acid generator (B)") in addition to salt (I). The acid generator (B) may be used alone or in combination of two or more.

The acid generator (B) may be either nonionic or ionic. Nonionic acid generators include sulfonate esters (eg 2-nitrobenzyl ester, aromatic sulfonate, oxime sulfonate, N-sulfonyloxyimide, sulfonyloxyketone, diazonaphthoquinone 4-sulfonate), sulfones (eg disulfone, ketosulfone, sulfonyldiazomethane) and the like. Typical ionic acid generators are onium salts containing onium cations (eg, diazonium salts, phosphonium salts, sulfonium salts, iodonium salts). The anions of the onium salts include sulfonate anions, sulfonylimide anions, sulfonylmethide anions, and the like.

Examples of the acid generator (B) include JP-A-63-26653, JP-A-55-164824, JP-A-62-69263, JP-A-63-146038, JP-A-63-163452, JP-A-62-153853, JP-A-63-146029, US Pat. No. 3,779,778, US Pat. A compound that generates an acid upon exposure to radiation as described in 1. above can be used. Moreover, you may use the compound manufactured by the well-known method. The acid generator (B) may be used in combination of two or more.

［式（Ｂ１）中、
Ｑ^ｂ１及びＱ^ｂ２は、それぞれ独立に、フッ素原子又は炭素数１～６のペルフルオロアルキル基を表す。
Ｌ^ｂ１は、炭素数１～２４の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水素基に含まれる水素原子は、フッ素原子又はヒドロキシ基で置換されていてもよい。
Ｙは、置換基を有していてもよいメチル基又は置換基を有していてもよい炭素数３～１８の脂環式炭化水素基を表し、該脂環式炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ（Ｏ）_２－又は－ＣＯ－に置き換わっていてもよい。
Ｚ１^＋は、有機カチオンを表す。］ The acid generator (B) is preferably a fluorine-containing acid generator, more preferably a salt represented by formula (B1) (hereinafter sometimes referred to as "acid generator (B1)").

[In the formula (B1),
Q ^b1 and Q ^b2 each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
L ^b1 represents a divalent saturated hydrocarbon group having 1 to 24 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O— or —CO—, and the saturated A hydrogen atom contained in the hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
Y represents an optionally substituted methyl group or an optionally substituted alicyclic hydrocarbon group having 3 to 18 carbon atoms, and included in the alicyclic hydrocarbon group- CH ₂ - may be replaced by -O-, -S(O) ₂ - or -CO-.
Z1 ⁺ represents an organic cation. ]

Q ^b1 and Q ^b2 , L ^b1 and Y in the acid generator (B1) are respectively the same as Q ¹ and Q ² , L ¹ and Y ^{1 of} the organic anion A in the salt (I); Examples of the anion in the acid generator (B1) include the same as the organic anion ^A- in the salt (I).

Organic cations include organic onium cations, organic sulfonium cations, organic iodonium cations, organic ammonium cations, benzothiazolium cations and organic phosphonium cations. Among these, organic sulfonium cations and organic iodonium cations are preferred, and arylsulfonium cations are more preferred. Specifically, a cation represented by any one of formulas (b2-1) to (b2-4) (hereinafter sometimes referred to as "cation (b2-1)" etc. depending on the formula number) is mentioned.

式（ｂ２－１）～式（ｂ２－４）において、
Ｒ^b4～Ｒ^b6は、それぞれ独立に、炭素数１～３０の脂肪族炭化水素基、炭素数３～３６の脂環式炭化水素基又は炭素数６～３６の芳香族炭化水素基を表し、該脂肪族炭化水素基に含まれる水素原子は、ヒドロキシ基、炭素数１～１２のアルコキシ基、炭素数３～１２の脂環式炭化水素基又は炭素数６～１８の芳香族炭化水素基で置換されていてもよく、該脂環式炭化水素基に含まれる水素原子は、ハロゲン原子、炭素数１～１８の脂肪族炭化水素基、炭素数２～４のアルキルカルボニル基又はグリシジルオキシ基で置換されていてもよく、該芳香族炭化水素基に含まれる水素原子は、ハロゲン原子、ヒドロキシ基又は炭素数１～１２のアルコキシ基で置換されていてもよい。
Ｒ^b4とＲ^b5とは、互いに結合してそれらが結合する硫黄原子と一緒になって環を形成してもよく、該環に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わってもよい。
Ｒ^b7及びＲ^b8は、それぞれ独立に、ヒドロキシ基、炭素数１～１２の脂肪族炭化水素基又は炭素数１～１２のアルコキシ基を表す。
ｍ２及びｎ２は、それぞれ独立に０～５のいずれかの整数を表す。
ｍ２が２以上のとき、複数のＲ^b7は同一でも異なってもよく、ｎ２が２以上のとき、複数のＲ^b8は同一でも異なってもよい。
Ｒ^b9及びＲ^b10は、それぞれ独立に、炭素数１～３６の脂肪族炭化水素基又は炭素数３～３６の脂環式炭化水素基を表す。
Ｒ^b9とＲ^b10とは、互いに結合してそれらが結合する硫黄原子と一緒になって環を形成してもよく、該環に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わってもよい。
Ｒ^b11は、水素原子、炭素数１～３６の脂肪族炭化水素基、炭素数３～３６の脂環式炭化水素基又は炭素数６～１８の芳香族炭化水素基を表す。
Ｒ^b12は、炭素数１～１２の脂肪族炭化水素基、炭素数３～１８の脂環式炭化水素基又は炭素数６～１８の芳香族炭化水素基を表し、該脂肪族炭化水素に含まれる水素原子は、炭素数６～１８の芳香族炭化水素基で置換されていてもよく、該芳香族炭化水素基に含まれる水素原子は、炭素数１～１２のアルコキシ基又は炭素数１～１２のアルキルカルボニルオキシ基で置換されていてもよい。
Ｒ^b11とＲ^b12とは、互いに結合してそれらが結合する－ＣＨ－ＣＯ－を含めて環を形成していてもよく、該環に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わってもよい。
Ｒ^b13～Ｒ^b18は、それぞれ独立に、ヒドロキシ基、炭素数１～１２の脂肪族炭化水素基又は炭素数１～１２のアルコキシ基を表す。
Ｌ^b31は、硫黄原子又は酸素原子を表す。
ｏ２、ｐ２、ｓ２、及びｔ２は、それぞれ独立に、０～５のいずれかの整数を表す。
ｑ２及びｒ２は、それぞれ独立に、０～４のいずれかの整数を表す。
ｕ２は０又は１を表す。
ｏ２が２以上のとき、複数のＲ^b13は同一又は相異なり、ｐ２が２以上のとき、複数のＲ^b14は同一又は相異なり、ｑ２が２以上のとき、複数のＲ^b15は同一又は相異なり、ｒ２が２以上のとき、複数のＲ^b16は同一又は相異なり、ｓ２が２以上のとき、複数のＲ^b17は同一又は相異なり、ｔ２が２以上のとき、複数のＲ^b18は同一又は相異なる。
脂肪族炭化水素基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、ｓｅｃ－ブチル基、ｔｅｒｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基及び２－エチルヘキシル基のアルキル基が挙げられる。特に、Ｒ^b9～Ｒ^b12の脂肪族炭化水素基は、好ましくは炭素数１～１２である。
脂環式炭化水素基としては、単環式又は多環式のいずれでもよく、単環式の脂環式炭化水素基としては、シクロプロピル基、シクロブチル基、シクロペンチル基、シクロへキシル基、シクロヘプチル基、シクロオクチル基、シクロデシル基等のシクロアルキル基が挙げられる。多環式の脂環式炭化水素基としては、デカヒドロナフチル基、アダマンチル基、ノルボルニル基及び下記の基等が挙げられる。

特に、Ｒ^b9～Ｒ^b12の脂環式炭化水素基は、好ましくは炭素数３～１８、より好ましくは炭素数４～１２である。
水素原子が脂肪族炭化水素基で置換された脂環式炭化水素基としては、メチルシクロヘキシル基、ジメチルシクロへキシル基、２－メチルアダマンタン－２－イル基、２－エチルアダマンタン－２－イル基、２－イソプロピルアダマンタン－２－イル基、メチルノルボルニル基、イソボルニル基等が挙げられる。水素原子が脂肪族炭化水素基で置換された脂環式炭化水素基においては、脂環式炭化水素基と脂肪族炭化水素基との合計炭素数が好ましくは２０以下である。
芳香族炭化水素基としては、フェニル基、トリル基、キシリル基、クメニル基、メシチル基、ｐ－エチルフェニル基、ｐ－ｔｅｒｔ－ブチルフェニル基、ｐ－シクロへキシルフェニル基、ｐ－アダマンチルフェニル基、ビフェニリル基、ナフチル基、フェナントリル基、２，６－ジエチルフェニル基、２－メチル－６－エチルフェニル基等のアリール基が挙げられる。
なお、芳香族炭化水素基に、脂肪族炭化水素基又は脂環式炭化水素基が含まれる場合は、炭素数１～１８の脂肪族炭化水素基及び炭素数３～１８の脂環式炭化水素基が好ましい。
水素原子がアルコキシ基で置換された芳香族炭化水素基としては、ｐ－メトキシフェニル基等が挙げられる。
水素原子が芳香族炭化水素基で置換された脂肪族炭化水素基としては、ベンジル基、フェネチル基、フェニルプロピル基、トリチル基、ナフチルメチル基、ナフチルエチル基等のアラルキル基が挙げられる。
アルコキシ基としては、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基、ペンチルオキシ基、ヘキシルオキシ基、ヘプチルオキシ基、オクチルオキシ基、デシルオキシ基及びドデシルオキシ基等が挙げられる。
アルキルカルボニル基としては、アセチル基、プロピオニル基及びブチリル基等が挙げられる。
ハロゲン原子としては、フッ素原子、塩素原子、臭素原子及びヨウ素原子等が挙げられる。
アルキルカルボニルオキシ基としては、メチルカルボニルオキシ基、エチルカルボニルオキシ基、プロピルカルボニルオキシ基、イソプロピルカルボニルオキシ基、ブチルカルボニルオキシ基、ｓｅｃ－ブチルカルボニルオキシ基、ｔｅｒｔ－ブチルカルボニルオキシ基、ペンチルカルボニルオキシ基、ヘキシルカルボニルオキシ基、オクチルカルボニルオキシ基及び２－エチルヘキシルカルボニルオキシ基等が挙げられる。
Ｒ^b4とＲ^b5とが互いに結合してそれらが結合する硫黄原子と一緒になって形成する環は、単環式、多環式、芳香族性、非芳香族性、飽和及び不飽和のいずれの環であってもよい。この環は、炭素数３～１８の環が挙げられ、好ましくは炭素数４～１８の環である。また、硫黄原子を含む環は、３員環～１２員環が挙げられ、好ましくは３員環～７員環であり、例えば下記の環が挙げられる。

Ｒ^b9とＲ^b10とが一緒になって形成する環は、単環式、多環式、芳香族性、非芳香族性、飽和及び不飽和のいずれの環であってもよい。この環は、３員環～１２員環が挙げられ、好ましくは３員環～７員環である。例えば、チオラン－１－イウム環（テトラヒドロチオフェニウム環）、チアン－１－イウム環、１，４－オキサチアン－４－イウム環等が挙げられる。
Ｒ^b11とＲ^b12とが一緒になって形成する環は、単環式、多環式、芳香族性、非芳香族性、飽和及び不飽和のいずれの環であってもよい。この環は、３員環～１２員環が挙げられ、好ましくは３員環～７員環である。オキソシクロヘプタン環、オキソシクロヘキサン環、オキソノルボルナン環、オキソアダマンタン環等が挙げられる。

In formulas (b2-1) to (b2-4),
R ^b4 to R ^b6 each independently represents an aliphatic hydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 36 carbon atoms or an aromatic hydrocarbon group having 6 to 36 carbon atoms; The hydrogen atom contained in the aliphatic hydrocarbon group is a hydroxy group, an alkoxy group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 12 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms. It may be substituted, and the hydrogen atom contained in the alicyclic hydrocarbon group is a halogen atom, an aliphatic hydrocarbon group having 1 to 18 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, or a glycidyloxy group. It may be substituted, and a hydrogen atom contained in the aromatic hydrocarbon group may be substituted with a halogen atom, a hydroxy group, or an alkoxy group having 1 to 12 carbon atoms.
R ^b4 and R ^b5 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, and —CH ₂ — contained in the ring may be —O—, —S— or -CO- may be substituted.
R ^b7 and R ^b8 each independently represent a hydroxy group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms.
m2 and n2 each independently represent an integer of 0 to 5;
When m2 is 2 or more, multiple R ^b7 may be the same or different, and when n2 is 2 or more, multiple R ^b8 may be the same or different.
R ^b9 and R ^b10 each independently represent an aliphatic hydrocarbon group having 1 to 36 carbon atoms or an alicyclic hydrocarbon group having 3 to 36 carbon atoms.
R ^b9 and R ^b10 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, and —CH ₂ — contained in the ring may be —O—, —S— or -CO- may be substituted.
R ^b11 represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 36 carbon atoms, an alicyclic hydrocarbon group having 3 to 36 carbon atoms or an aromatic hydrocarbon group having 6 to 18 carbon atoms.
R ^b12 represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms or an aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be substituted with an aromatic hydrocarbon group having 6 to 18 carbon atoms, and the hydrogen atoms contained in the aromatic hydrocarbon group are alkoxy groups having 1 to 12 carbon atoms or 1 to 1 carbon atoms. It may be substituted with 12 alkylcarbonyloxy groups.
R ^b11 and R ^b12 may be bonded to each other to form a ring including —CH—CO— to which they are bonded, and —CH ₂ — contained in the ring may be —O—, —S - or -CO- may be substituted.
R ^b13 to R ^b18 each independently represent a hydroxy group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms.
L ^b31 represents a sulfur atom or an oxygen atom.
o2, p2, s2, and t2 each independently represent an integer of 0 to 5;
q2 and r2 each independently represent an integer of 0 to 4;
u2 represents 0 or 1;
When o2 is 2 or more, multiple R ^b13 are the same or different, when p2 is 2 or more, multiple R ^b14 are the same or different, and when q2 is 2 or more, multiple R ^b15 are the same or different. , when r2 is 2 or more, the plurality of R ^b16 are the same or different; when s2 is 2 or more, the plurality of R ^b17 are the same or different; when t2 is 2 or more, the plurality of R ^b18 are the same or different; different.
Examples of aliphatic hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl and 2-ethylhexyl groups. mentioned. In particular, the aliphatic hydrocarbon groups of R ^b9 to R ^b12 preferably have 1 to 12 carbon atoms.
The alicyclic hydrocarbon group may be either monocyclic or polycyclic, and the monocyclic alicyclic hydrocarbon group includes a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclo Cycloalkyl groups such as a heptyl group, a cyclooctyl group, and a cyclodecyl group can be mentioned. The polycyclic alicyclic hydrocarbon group includes decahydronaphthyl group, adamantyl group, norbornyl group and the following groups.

In particular, the alicyclic hydrocarbon groups of R ^b9 to R ^b12 preferably have 3 to 18 carbon atoms, more preferably 4 to 12 carbon atoms.
Alicyclic hydrocarbon groups in which hydrogen atoms are substituted with aliphatic hydrocarbon groups include methylcyclohexyl group, dimethylcyclohexyl group, 2-methyladamantan-2-yl group, and 2-ethyladamantan-2-yl group. , 2-isopropyladamantan-2-yl group, methylnorbornyl group, isobornyl group and the like. In the alicyclic hydrocarbon group in which a hydrogen atom is substituted with an aliphatic hydrocarbon group, the total carbon number of the alicyclic hydrocarbon group and the aliphatic hydrocarbon group is preferably 20 or less.
The aromatic hydrocarbon group includes a phenyl group, a tolyl group, a xylyl group, a cumenyl group, a mesityl group, a p-ethylphenyl group, a p-tert-butylphenyl group, a p-cyclohexylphenyl group and a p-adamantylphenyl group. , biphenylyl group, naphthyl group, phenanthryl group, 2,6-diethylphenyl group and 2-methyl-6-ethylphenyl group.
When the aromatic hydrocarbon group contains an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, an aliphatic hydrocarbon group having 1 to 18 carbon atoms and an alicyclic hydrocarbon group having 3 to 18 carbon atoms groups are preferred.
Aromatic hydrocarbon groups in which a hydrogen atom is substituted with an alkoxy group include a p-methoxyphenyl group and the like.
Aliphatic hydrocarbon groups in which hydrogen atoms are substituted with aromatic hydrocarbon groups include aralkyl groups such as benzyl, phenethyl, phenylpropyl, trityl, naphthylmethyl and naphthylethyl groups.
Alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy and dodecyloxy groups.
An acetyl group, a propionyl group, a butyryl group, etc. are mentioned as an alkylcarbonyl group.
Halogen atoms include fluorine, chlorine, bromine and iodine atoms.
The alkylcarbonyloxy group includes a methylcarbonyloxy group, an ethylcarbonyloxy group, a propylcarbonyloxy group, an isopropylcarbonyloxy group, a butylcarbonyloxy group, a sec-butylcarbonyloxy group, a tert-butylcarbonyloxy group and a pentylcarbonyloxy group. , hexylcarbonyloxy group, octylcarbonyloxy group and 2-ethylhexylcarbonyloxy group.
The ring formed by R ^b4 and R ^b5 bonded together with the sulfur atom to which they are bonded may be monocyclic, polycyclic, aromatic, non-aromatic, saturated or unsaturated. may be a ring of This ring includes a ring having 3 to 18 carbon atoms, preferably a ring having 4 to 18 carbon atoms. Further, the ring containing a sulfur atom includes a 3- to 12-membered ring, preferably a 3- to 7-membered ring, and examples thereof include the following rings.

The ring formed by R ^b9 and R ^b10 together may be a monocyclic, polycyclic, aromatic, non-aromatic, saturated or unsaturated ring. This ring includes a 3- to 12-membered ring, preferably a 3- to 7-membered ring. Examples thereof include thiolan-1-ium ring (tetrahydrothiophenium ring), thian-1-ium ring, 1,4-oxathian-4-ium ring and the like.
The ring formed by R ^b11 and R ^b12 together may be a monocyclic, polycyclic, aromatic, non-aromatic, saturated or unsaturated ring. This ring includes a 3- to 12-membered ring, preferably a 3- to 7-membered ring. oxocycloheptane ring, oxocyclohexane ring, oxonorbornane ring, oxoadamantane ring and the like.

Among the cations (b2-1) to (b2-4), the cation (b2-1) is preferred.
Examples of the cation (b2-1) include the following cations.

Examples of the cation (b2-2) include the following cations.

Examples of the cation (b2-3) include the following cations.

Examples of the cation (b2-4) include the following cations.

The acid generator (B) is a combination of the above sulfonate anion and the above organic cation, and these can be combined arbitrarily. As the acid generator (B), preferably formulas (B1a-1) to (B1a-3) and formulas (B1a-7) to (B1a-16), formulas (B1a-18), and formulas (B1a- 19), a combination of an anion represented by any one of formulas (B1a-22) to (B1a-34) and a cation (b2-1) or a cation (b2-3).

As the acid generator (B), those represented by formulas (B1-1) to (B1-48) are preferred. Among them, those containing an arylsulfonium cation are preferable, and formulas (B1-1) to (B1-3), formulas (B1-5) to (B1-7), formulas (B1-11) to (B1-14) ), formulas (B1-20) to (B1-26), formulas (B1-29), and formulas (B1-31) to (B1-48) are particularly preferred.

When the acid generator contains the salt (I) and the acid generator (B), the ratio of the contents of the salt (I) and the acid generator (B) (mass ratio; salt (I): acid generator ( B)) is generally 1:99 to 99:1, preferably 2:98 to 98:2, more preferably 5:95 to 95:5, still more preferably 10:90 to 90 :10, particularly preferably 15:85 to 85:15.

<Resist composition>
The resist composition of the present invention contains an acid generator containing salt (I) and a resin having an acid-labile group (hereinafter sometimes referred to as "resin (A)"). Here, the term "acid-labile group" refers to a structure having a leaving group, the leaving group being eliminated by contact with an acid, and having a constitutional unit having a hydrophilic group (for example, a hydroxy group or a carboxy group). means a group that converts to units.
The resist composition of the present invention preferably contains a quencher (hereinafter sometimes referred to as "quencher (C)") such as a salt that generates an acid that is weaker in acidity than the acid generated by the acid generator. , a solvent (hereinafter sometimes referred to as "solvent (E)").

<Acid generator>
In the resist composition of the present invention, the content of the acid generator is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 3 parts by mass or more and 35 parts by mass or less, relative to 100 parts by mass of the resin (A). is.

<Resin (A)>
Resin (A) has a structural unit having an acid-labile group (hereinafter sometimes referred to as "structural unit (a1)"). The resin (A) preferably further contains structural units other than the structural unit (a1). Structural units other than the structural unit (a1) include structural units having no acid-labile group (hereinafter sometimes referred to as "structural unit (s)"), structural units other than the structural unit (a1) and the structural unit (s). Structural units (for example, structural units having a halogen atom described later (hereinafter sometimes referred to as "structural unit (a4)"), structural units having a non-eliminating hydrocarbon group described later (hereinafter referred to as "structural unit (a5) ) and other structural units derived from monomers known in the art.

［式（１）中、Ｒ^ａ１、Ｒ^ａ２及びＲ^ａ３は、それぞれ独立に、炭素数１～８のアルキル基、炭素数３～２０の脂環式炭化水素基又はこれらを組み合わせた基を表すか、Ｒ^a1及びＲ^a2は互いに結合してそれらが結合する炭素原子とともに炭素数３～２０の非芳香族炭化水素環を形成する。
ｍａ及びｎａは、それぞれ独立して、０又は１を表し、ｍａ及びｎａの少なくとも一方は１を表す。
＊は結合部位を表す。］

［式（２）中、Ｒ^ａ１’及びＲ^ａ２’は、それぞれ独立に、水素原子又は炭素数１～１２の炭化水素基を表し、Ｒ^ａ３’は、炭素数１～２０の炭化水素基を表すか、Ｒ^ａ２’及びＲ^ａ３’は互いに結合してそれらが結合する炭素原子及びＸとともに炭素数３～２０の複素環を形成し、該炭化水素基及び該複素環に含まれる－ＣＨ_２－は、－Ｏ－又は－Ｓ－で置き換わってもよい。
Ｘは、酸素原子又は硫黄原子を表す。
ｎａ’は、０又は１を表す。
＊は結合部位を表す。］ <Structural unit (a1)>
The structural unit (a1) is derived from a monomer having an acid-labile group (hereinafter sometimes referred to as "monomer (a1)").
The acid-labile group contained in the resin (A) is a group represented by formula (1) (hereinafter also referred to as group (1)) and/or a group represented by formula (2) (hereinafter referred to as group (2 )) is preferable.

[In formula (1), R ^a1 , R ^a2 and R ^a3 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a group combining these; Alternatively, R ^a1 and R ^a2 are bonded to each other to form a non-aromatic hydrocarbon ring having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded.
ma and na each independently represent 0 or 1, and at least one of ma and na represents 1;
* represents a binding site. ]

[In formula (2), R ^a1′ and R ^a2′ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and R ^a3′ represents a hydrocarbon group having 1 to 20 carbon atoms. or R ^a2′ and R ^a3′ are bonded to each other to form a heterocyclic ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded and X, and —CH ₂ contained in the hydrocarbon group and the heterocyclic ring - may be replaced by -O- or -S-.
X represents an oxygen atom or a sulfur atom.
na' represents 0 or 1;
* represents a binding site. ]

アルキル基と脂環式炭化水素基とを組み合わせた基としては、例えば、メチルシクロヘキシル基、ジメチルシクロへキシル基、メチルノルボルニル基、シクロヘキシルメチル基、アダマンチルメチル基、アダマンチルジメチル基、ノルボルニルエチル基等が挙げられる。
好ましくは、ｍａは０であり、ｎａは１である。
Ｒ^a1及びＲ^a2が互いに結合して非芳香族炭化水素環を形成する場合の－Ｃ（Ｒ^a1）（Ｒ^a2）（Ｒ^a3）としては、下記の環が挙げられる。非芳香族炭化水素環は、好ましくは炭素数３～１２である。＊は－Ｏ－との結合部位を表す。

Examples of alkyl groups for R ^a1 , R ^a2 and R ^a3 include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group and octyl group.
The alicyclic hydrocarbon groups for R ^a1 , R ^a2 and R ^a3 may be either monocyclic or polycyclic. The monocyclic alicyclic hydrocarbon group includes cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group and cyclooctyl group. Examples of polycyclic alicyclic hydrocarbon groups include decahydronaphthyl group, adamantyl group, norbornyl group and the following groups (* represents a bonding site). The alicyclic hydrocarbon groups of R ^a1 , R ^a2 and R ^a3 preferably have 3 to 16 carbon atoms.

Groups in which an alkyl group and an alicyclic hydrocarbon group are combined include, for example, methylcyclohexyl group, dimethylcyclohexyl group, methylnorbornyl group, cyclohexylmethyl group, adamantylmethyl group, adamantyldimethyl group, norbornyl An ethyl group etc. are mentioned.
Preferably, ma is 0 and na is 1.
-C(R ^a1 )(R ^a2 )(R ^a3 ) when R ^a1 and R ^a2 combine to form a non-aromatic hydrocarbon ring include the following rings. The non-aromatic hydrocarbon ring preferably has 3 to 12 carbon atoms. * represents a binding site with -O-.

Ｒ^ａ１’及びＲ^ａ２’のうち、少なくとも１つは水素原子であることが好ましい。
ｎａ’は、好ましくは０である。 Examples of hydrocarbon groups for R ^a1′ , R ^a2′ and R ^a3′ include alkyl groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, groups formed by combining these groups, and the like.
Examples of the alkyl group and the alicyclic hydrocarbon group include the same groups as those listed for R ^a1 , R ^a2 and R ^a3 .
Aromatic hydrocarbon groups include aryl groups such as phenyl, naphthyl, anthryl, biphenyl, and phenanthryl groups.
Examples of the combined group include a group obtained by combining the aforementioned alkyl group and an alicyclic hydrocarbon group (for example, a cycloalkylalkyl group), an aralkyl group such as a benzyl group, an aromatic hydrocarbon group having an alkyl group (p-methyl phenyl group, p-tert-butylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), alicyclic hydrocarbon groups aromatic hydrocarbon groups (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as phenylcyclohexyl group, and the like.
When R ^a2′ and R ^a3′ are bonded to each other to form a heterocyclic ring together with the carbon atom to which they are bonded and X, —C(R ^a1′ )(R ^a3′ )—X—R ^a2′ is represented by the following ring. * represents the binding site.

At least one of R ^a1′ and R ^a2′ is preferably a hydrogen atom.
na' is preferably zero.

Group (1) includes the following groups.
A group in which R ^a1 , R ^a2 and R ^a3 in formula (1) are alkyl groups, ma=0 and na=1. The group is preferably a tert-butoxycarbonyl group.
In formula (1), R ^a1 and R ^a2 form an adamantyl group together with the carbon atoms to which they are attached, R ^a3 is an alkyl group, ma = 0 and na = 1. .
A group in which R ^a1 and R ^a2 are each independently an alkyl group, R ^a3 is an adamantyl group, ma=0 and na=1 in formula (1).
Specific examples of the group (1) include the following groups. * represents a binding site.

Specific examples of group (2) include the following groups. * represents a binding site.

Monomer (a1) is preferably a monomer having an acid labile group and an ethylenically unsaturated bond, more preferably a (meth)acrylic monomer having an acid labile group.

Among (meth)acrylic monomers having an acid-labile group, those having an alicyclic hydrocarbon group having 5 to 20 carbon atoms are preferred. When the resin (A) having a structural unit derived from the monomer (a1) having a bulky structure such as an alicyclic hydrocarbon group is used in the resist composition, the resolution of the resist pattern can be improved.

［式（ａ１－０）、式（ａ１－１）及び式（ａ１－２）中、
Ｌ^a01、Ｌ^ａ１及びＬ^ａ２は、それぞれ独立に、－Ｏ－又は＊－Ｏ－（ＣＨ_２）_ｋ１－ＣＯ－Ｏ－を表し、ｋ１は１～７のいずれかの整数を表し、＊は－ＣＯ－との結合部位を表す。
Ｒ^a01、Ｒ^ａ４及びＲ^ａ５は、それぞれ独立に、水素原子又はメチル基を表す。
Ｒ^a02、Ｒ^a03及びＲ^a04は、それぞれ独立に、炭素数１～８のアルキル基、炭素数３～１８の脂環式炭化水素基又はこれらを組み合わせた基を表す。
Ｒ^ａ６及びＲ^ａ７は、それぞれ独立に、炭素数１～８のアルキル基、炭素数３～１８の脂環式炭化水素基又はこれらを組合せることにより形成される基を表す。
ｍ１は０～１４のいずれかの整数を表す。
ｎ１は０～１０のいずれかの整数を表す。
ｎ１’は０～３のいずれかの整数を表す。］ The structural unit derived from a (meth)acrylic monomer having group (1) is preferably a structural unit represented by formula (a1-0) (hereinafter sometimes referred to as structural unit (a1-0).) , a structural unit represented by formula (a1-1) (hereinafter sometimes referred to as structural unit (a1-1)) or a structural unit represented by formula (a1-2) (hereinafter, structural unit (a1- 2) may be mentioned). These may be used alone or in combination of two or more.

[In formula (a1-0), formula (a1-1) and formula (a1-2),
L ^a01 , L ^a1 and L ^a2 each independently represent -O- or *-O-(CH ₂ ) _k1 -CO-O-, k1 represents an integer of 1 to 7, * is represents the binding site with -CO-.
R ^a01 , R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group.
R ^a02 , R ^a03 and R ^a04 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or a combination thereof.
R ^a6 and R ^a7 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or a group formed by combining these.
m1 represents any integer from 0 to 14;
n1 represents any integer from 0 to 10;
n1' represents an integer of 0 to 3; ]

R ^a01 , R ^a4 and R ^a5 are preferably methyl groups.
L ^a01 , L ^a1 and L ^a2 are preferably an oxygen atom or *—O—(CH ₂ ) _k01 —CO—O— (provided that k01 is preferably any integer of 1 to 4, more preferably is 1.), more preferably an oxygen atom.
The alkyl groups, alicyclic hydrocarbon groups and groups in which these are combined for R ^a02 , R ^a03 , R ^a04 , R ^a6 and R ^a7 are the same as the groups listed for R ^a1 to R ^a3 in formula (1). groups.
The alkyl group in R ^a02 , R ^a03 and R ^a04 preferably has 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group, still more preferably a methyl group.
The alkyl group in R ^a6 and R ^a7 preferably has 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group or an isopropyl group, still more preferably an ethyl group or an isopropyl group.
The alicyclic hydrocarbon groups of R ^a02 , R ^a03 , R ^a04 , R ^a6 and R ^a7 preferably have 5 to 12 carbon atoms, more preferably 5 to 10 carbon atoms.
It is preferable that the combined group of an alkyl group and an alicyclic hydrocarbon group have a total carbon number of 18 or less.
R ^a02 and R ^a03 are each independently preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group.
R ^a04 is preferably an alkyl group having 1 to 6 carbon atoms or an alicyclic hydrocarbon group having 5 to 12 carbon atoms, more preferably a methyl group, an ethyl group, a cyclohexyl group or an adamantyl group.
R ^a6 and R ^a7 are each independently preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group or an isopropyl group, still more preferably an ethyl group or an isopropyl group.
m1 is preferably an integer from 0 to 3, more preferably 0 or 1.
n1 is preferably an integer from 0 to 3, more preferably 0 or 1.
n1' is preferably 0 or 1.

As the structural unit (a1-0), for example, a structural unit represented by any one of formulas (a1-0-1) to (a1-0-12) and R ^a01 in the structural unit (a1-0) Structural units in which the corresponding methyl group is replaced with a hydrogen atom are exemplified, and structural units represented by any one of formulas (a1-0-1) to (a1-0-10) are preferred.

Examples of structural units (a1-1) include structural units derived from monomers described in JP-A-2010-204646. Among them, a structural unit represented by any one of formulas (a1-1-1) to (a1-1-4) and a methyl group corresponding to R ^a4 in structural unit (a1-1) is replaced with a hydrogen atom. Structural units are preferred, and structural units represented by any one of formulas (a1-1-1) to (a1-1-4) are more preferred.

The structural unit (a1-2) corresponds to a structural unit represented by any one of formulas (a1-2-1) to (a1-2-6) and R ^a5 in the structural unit (a1-2). Structural units in which a methyl group is substituted with a hydrogen atom are included, and formulas (a1-2-2), (a1-2-5) and (a1-2-6) are preferred.

When the resin (A) contains the structural unit (a1-0) and/or the structural unit (a1-1) and/or the structural unit (a1-2), the total content of these is the total structure of the resin (A) It is usually 10 to 95 mol%, preferably 15 to 90 mol%, more preferably 15 to 85 mol%, even more preferably 15 to 70 mol%, still more preferably It is 15 to 65 mol %, particularly preferably 20 to 65 mol %.

［式（ａ１－４）中、
Ｒ^a32は、水素原子、ハロゲン原子、又は、ハロゲン原子を有していてもよい炭素数１～６のアルキル基を表す。
Ｒ^a33は、ハロゲン原子、ヒドロキシ基、炭素数１～６のアルキル基、炭素数１～６のアルコキシ基、炭素数２～４のアルキルカルボニル基、炭素数２～４のアルキルカルボニルオキシ基、アクリロイルオキシ基又はメタクリロイルオキシ基を表す。
ｌａは０～４のいずれかの整数を表す。ｌａが２以上である場合、複数のＲ^a33は互いに同一であっても異なってもよい。
Ｒ^a34及びＲ^a35はそれぞれ独立に、水素原子又は炭素数１～１２の炭化水素基を表し、Ｒ^a36は、炭素数１～２０の炭化水素基を表すか、Ｒ^a35及びＲ^a36は互いに結合してそれらが結合する－Ｃ－Ｏ－とともに炭素数２～２０の２価の炭化水素基を形成し、該炭化水素基及び該２価の炭化水素基に含まれる－ＣＨ₂－は、－Ｏ－又は－Ｓ－で置き換わってもよい。］ Structural units having group (2) in structural unit (a1) include structural units represented by formula (a1-4) (hereinafter sometimes referred to as “structural unit (a1-4)”). .

[In the formula (a1-4),
R ^a32 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
R ^a33 is a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, acryloyl It represents an oxy group or a methacryloyloxy group.
la represents an integer of 0 to 4; When la is 2 or more, a plurality of R ^a33 may be the same or different.
R ^a34 and R ^a35 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, R ^a36 represents a hydrocarbon group having 1 to 20 carbon atoms, or R ^a35 and R ^a36 are bonded to each other to form a C2-C20 divalent hydrocarbon group together with -C-O- to which they are bonded, and -CH ₂ - contained in the hydrocarbon group and the divalent hydrocarbon group is - O- or -S- may be substituted. ]

Examples of alkyl groups for R ^a32 and R ^a33 include methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group and hexyl group. The alkyl group is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group, even more preferably a methyl group.
Halogen atoms in R ^a32 and R ^a33 include fluorine, chlorine and bromine atoms.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom include trifluoromethyl group, difluoromethyl group, methyl group, perfluoroethyl group, 2,2,2-trifluoroethyl group, 1,1 , 2,2-tetrafluoroethyl group, ethyl group, perfluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, propyl group, perfluorobutyl group, 1,1,2,2,3,3 , 4,4-octafluorobutyl group, butyl group, perfluoropentyl group, 2,2,3,3,4,4,5,5,5-nonafluoropentyl group, pentyl group, hexyl group, perfluorohexyl group, etc. are mentioned.
Alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy and hexyloxy groups. Among them, an alkoxy group having 1 to 4 carbon atoms is preferable, a methoxy group or an ethoxy group is more preferable, and a methoxy group is even more preferable.
Alkylcarbonyl groups include acetyl, propionyl and butyryl groups.
An acetyloxy group, a propionyloxy group, a butyryloxy group, etc. are mentioned as an alkylcarbonyloxy group.
Hydrocarbon groups for R ^a34 , R ^a35 and R ^a36 include alkyl groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups in which these are combined. Examples include the same alkyl groups and alicyclic hydrocarbon groups as R ^a02 , R ^a03 , R ^a04 , R ^a6 and R ^a7 .
Aromatic hydrocarbon groups include aryl groups such as phenyl, naphthyl, anthryl, biphenyl, and phenanthryl groups.
Examples of the combined group include a group obtained by combining the aforementioned alkyl group and an alicyclic hydrocarbon group (for example, a cycloalkylalkyl group), an aralkyl group such as a benzyl group, an aromatic hydrocarbon group having an alkyl group (p-methyl phenyl group, p-tert-butylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), alicyclic hydrocarbon groups aromatic hydrocarbon groups (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.), aryl-cyclohexyl groups such as phenylcyclohexyl group, and the like. In particular, R ^a36 is an alkyl group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group formed by combining these groups. are mentioned.

In formula (a1-4), R ^a32 is preferably a hydrogen atom.
R ^a33 is preferably an alkoxy group having 1 to 4 carbon atoms, more preferably a methoxy group or an ethoxy group, and still more preferably a methoxy group.
la is preferably 0 or 1, more preferably 0.
R ^a34 is preferably a hydrogen atom.
R ^a35 is preferably an alkyl group having 1 to 12 carbon atoms or an alicyclic hydrocarbon group, more preferably a methyl group or an ethyl group.
The hydrocarbon group of R ^a36 is preferably an alkyl group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a combination of these A group to be formed, more preferably an alkyl group having 1 to 18 carbon atoms, an alicyclic aliphatic hydrocarbon group having 3 to 18 carbon atoms or an aralkyl group having 7 to 18 carbon atoms. The alkyl group and alicyclic hydrocarbon group in R ^a36 are preferably unsubstituted. The aromatic hydrocarbon group for R ^a36 is preferably an aromatic ring having an aryloxy group with 6 to 10 carbon atoms.
--OC(R ^a34 )(R ^a35 )-OR ^a36 in the structural unit (a1-4) is eliminated upon contact with an acid (eg, p-toluenesulfonic acid) to form a hydroxy group.

Examples of structural units (a1-4) include structural units derived from monomers described in JP-A-2010-204646. Preferably, structural units represented by formulas (a1-4-1) to (a1-4-12) and structures in which the hydrogen atom corresponding to R ^a32 in the structural unit (a1-4) is replaced with a methyl group units, more preferably structural units represented by formulas (a1-4-1) to (a1-4-5) and formula (a1-4-10).

When the resin (A) contains the structural unit (a1-4), the content thereof is preferably 10 to 95 mol%, preferably 15 to 90 mol%, based on the total of all structural units of the resin (A). It is more preferably 20 to 85 mol %, even more preferably 20 to 70 mol %, and particularly preferably 20 to 60 mol %.

式（ａ１－５）中、
Ｒ^a8は、ハロゲン原子を有していてもよい炭素数１～６のアルキル基、水素原子又はハロゲン原子を表す。
Ｚ^a1は、単結合又は＊－（ＣＨ₂）_h3－ＣＯ－Ｌ⁵⁴－を表し、ｈ３は１～４のいずれかの整数を表し、＊は、Ｌ⁵¹との結合部位を表す。
Ｌ⁵¹、Ｌ⁵²、Ｌ⁵³及びＬ⁵⁴は、それぞれ独立に、－Ｏ－又は－Ｓ－を表す。
ｓ１は、１～３のいずれかの整数を表す。
ｓ１’は、０～３のいずれかの整数を表す。 Structural units derived from (meth)acrylic monomers having group (2) include structural units represented by formula (a1-5) (hereinafter sometimes referred to as “structural unit (a1-5)”). be done.

In formula (a1-5),
R ^a8 represents an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, a hydrogen atom or a halogen atom.
Z ^a1 represents a single bond or *—(CH ₂ ) _h3 —CO—L ⁵⁴ —, h3 represents an integer of 1 to 4, and * represents a binding site with L ⁵¹ .
L ⁵¹ , L ⁵² , L ⁵³ and L ⁵⁴ each independently represent -O- or -S-.
s1 represents an integer of 1 to 3;
s1' represents any integer from 0 to 3;

Halogen atoms include fluorine atoms and chlorine atoms, with fluorine atoms being preferred.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, fluoromethyl group and trifluoro A methyl group is mentioned.
In formula (a1-5), R ^a8 is preferably a hydrogen atom, a methyl group or a trifluoromethyl group.
L ⁵¹ is preferably an oxygen atom.
Preferably, one of L ⁵² and L ⁵³ is —O— and the other is —S—.
As for s1, 1 is preferable.
s1' is preferably an integer of 0-2.
Z ^a1 is preferably a single bond or *—CH ₂ —CO—O—.

Examples of structural units (a1-5) include structural units derived from monomers described in JP-A-2010-61117. Among them, structural units represented by formulas (a1-5-1) to (a1-5-4) are preferable, and represented by formula (a1-5-1) or formula (a1-5-2) Structural units are more preferred.

When the resin (A) contains the structural unit (a1-5), its content is preferably 1 to 50 mol%, more preferably 3 to 45 mol%, based on the total structural units of the resin (A). , more preferably 5 to 40 mol %, and even more preferably 5 to 30 mol %.

The structural unit (a1) also includes the following structural units.

When the resin (A) contains structural units such as the above (a1-3-1) to (a1-3-7), the content is 10 to 10 to the total structural units of the resin (A). 95 mol % is preferred, 15 to 90 mol % is more preferred, 20 to 85 mol % is even more preferred, 20 to 70 mol % is even more preferred, and 20 to 60 mol % is particularly preferred.

<Structural unit (s)>
Structural unit (s) is derived from a monomer having no acid-labile group (hereinafter sometimes referred to as "monomer (s)"). As a monomer leading to the structural unit (s), a monomer having no acid-labile group known in the field of resists can be used.
The structural unit (s) preferably has a hydroxy group or a lactone ring. A structural unit having a hydroxy group and no acid-labile group (hereinafter sometimes referred to as "structural unit (a2)") and/or a structure having a lactone ring and no acid-labile group When a resin having a unit (hereinafter sometimes referred to as "structural unit (a3)") is used in the resist composition of the present invention, the resolution of the resist pattern and adhesion to the substrate can be improved.

<Structural unit (a2)>
The hydroxy group possessed by the structural unit (a2) may be an alcoholic hydroxy group or a phenolic hydroxy group.
When producing a resist pattern from the resist composition of the present invention, when using a high-energy beam such as a KrF excimer laser (248 nm), an electron beam, or EUV (extreme ultraviolet light) as an exposure light source, the structural unit (a2) , it is preferable to use a structural unit (a2) having a phenolic hydroxy group. When using an ArF excimer laser (193 nm) or the like, the structural unit (a2) is preferably a structural unit (a2) having an alcoholic hydroxy group, and more preferably a structural unit (a2-1) described later. preferable. As the structural unit (a2), one type may be contained alone, or two or more types may be contained.

［式（ａ２－Ａ）中、
Ｒ^a50は、水素原子、ハロゲン原子又はハロゲン原子を有していてもよい炭素数１～６のアルキル基を表す。
Ｒ^a51は、ハロゲン原子、ヒドロキシ基、炭素数１～６のアルキル基、炭素数１～６のアルコキシ基、炭素数２～４のアルキルカルボニル基、炭素数２～４のアルキルカルボニルオキシ基、アクリロイルオキシ基又はメタクリロイルオキシ基を表す。
Ａ^a50は、単結合又は＊－Ｘ^a51－（Ａ^a52－Ｘ^a52）_nb－を表し、＊は－Ｒ^a50が結合する炭素原子との結合部位を表す。
Ａ^a52は、それぞれ独立に、炭素数１～６のアルカンジイル基を表す。
Ｘ^a51及びＸ^a52は、それぞれ独立に、－Ｏ－、－ＣＯ－Ｏ－又は－Ｏ－ＣＯ－を表す。
ｎｂは、０又は１を表す。
ｍｂは０～４のいずれかの整数を表す。ｍｂが２以上のいずれかの整数である場合、複数のＲ^a51は互いに同一であっても異なってもよい。］ Structural units having a phenolic hydroxy group in structural units (a2) include structural units represented by formula (a2-A) (hereinafter sometimes referred to as “structural unit (a2-A)”).

[In the formula (a2-A),
R ^a50 represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
R ^a51 is a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, acryloyl It represents an oxy group or a methacryloyloxy group.
A ^a50 represents a single bond or *-X ^a51 -(A ^a52 -X ^a52 ) _nb -, and * represents a bonding site with the carbon atom to which -R ^a50 bonds.
Each A ^a52 independently represents an alkanediyl group having 1 to 6 carbon atoms.
X ^a51 and X ^a52 each independently represent -O-, -CO-O- or -O-CO-.
nb represents 0 or 1;
mb represents an integer from 0 to 4; When mb is any integer of 2 or more, multiple R ^a51 may be the same or different. ]

Halogen atoms in R ^a50 include fluorine, chlorine and bromine atoms.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom for R ^a50 include a trifluoromethyl group, a difluoromethyl group, a methyl group, a perfluoroethyl group, a 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, ethyl group, perfluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, propyl group, perfluorobutyl group, 2,2,3,3, 4,4,4-heptafluorobutyl group, 1,1,2,2,3,3,4,4-octafluorobutyl group, butyl group, perfluoropentyl group, 2,2,3,3,4,4 , 5,5,5-nonafluoropentyl, pentyl, hexyl and perfluorohexyl groups.
R ^a50 is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, a methyl group or an ethyl group, even more preferably a hydrogen atom or a methyl group.
Examples of alkyl groups for R ^a51 include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl and hexyl groups.
Alkoxy groups for R ^a51 include methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy and tert-butoxy groups. An alkoxy group having 1 to 4 carbon atoms is preferred, a methoxy group or an ethoxy group is more preferred, and a methoxy group is even more preferred.
The alkylcarbonyl group for R ^a51 includes an acetyl group, a propionyl group and a butyryl group.
The alkylcarbonyloxy group for R ^a51 includes an acetyloxy group, a propionyloxy group and a butyryloxy group.
R ^a51 is preferably a methyl group.

*-X ^a51 -(A ^a52 -X ^a52 ) _nb - includes *-O-, *-CO-O-, *-O-CO-, *-CO-O-A ^a52 -CO-O-, *-O-CO-A ^a52 -O-, *-O-A ^a52 -CO-O-, *-CO-O-A ^a52 -O-CO-, *-O-CO-A ^a52 -O-CO -, and the like. Among them, *-CO-O-, *-CO-OA ^a52 -CO-O- or *-OA ^a52 -CO-O- is preferred.

The alkanediyl groups include methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane- 1,6-diyl group, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group and 2 -methylbutane-1,4-diyl group and the like.
A ^a52 is preferably a methylene group or an ethylene group.

A ^a50 is preferably a single bond, *—CO—O— or *—CO—O—A ^a52 —CO—O—, a single bond, *—CO—O— or *—CO—O—CH ₂ --CO--O-- is more preferred, and a single bond or *--CO--O-- is even more preferred.

mb is preferably 0, 1 or 2, more preferably 0 or 1, and particularly preferably 0.
The hydroxy group is preferably bonded to the o-position or p-position of the benzene ring, more preferably bonded to the p-position.

Examples of the structural unit (a2-A) include structural units derived from monomers described in JP-A-2010-204634 and JP-A-2012-12577.

The structural unit (a2-A) includes structural units represented by formulas (a2-2-1) to (a2-2-6) and formulas (a2-2-1) to (a2-2- In the structural unit represented by 6), a structural unit in which the methyl group corresponding to R ^a50 in the structural unit (a2-A) is replaced with a hydrogen atom can be mentioned. Structural unit (a2-A) includes a structural unit represented by formula (a2-2-1), a structural unit represented by formula (a2-2-3), and a structural unit represented by formula (a2-2-6). and the structural unit represented by formula (a2-2-1), the structural unit represented by formula (a2-2-3) or the structural unit represented by formula (a2-2-6), A structural unit in which the methyl group corresponding to R ^a50 in the structural unit (a2-A) is replaced with a hydrogen atom is preferred.

When the structural unit (a2-A) is contained in the resin (A), the content of the structural unit (a2-A) is preferably 5 to 80 mol% of the total structural units, more preferably It is 10 to 70 mol %, more preferably 15 to 65 mol %, still more preferably 20 to 65 mol %.
The structural unit (a2-A) can be included in the resin (A), for example, by polymerizing the structural unit (a1-4) and then treating with an acid such as p-toluenesulfonic acid. Also, the structural unit (a2-A) can be included in the resin (A) by polymerizing with acetoxystyrene or the like and then treating with an alkali such as tetramethylammonium hydroxide.

式（ａ２－１）中、
Ｌ^a3は、－Ｏ－又は＊－Ｏ－（ＣＨ₂）_k2－ＣＯ－Ｏ－を表し、
ｋ２は１～７のいずれかの整数を表す。＊は－ＣＯ－との結合部位を表す。
Ｒ^a14は、水素原子又はメチル基を表す。
Ｒ^a15及びＲ^a16は、それぞれ独立に、水素原子、メチル基又はヒドロキシ基を表す。
ｏ１は、０～１０のいずれかの整数を表す。 A structural unit having an alcoholic hydroxy group in the structural unit (a2) includes a structural unit represented by formula (a2-1) (hereinafter sometimes referred to as "structural unit (a2-1)").

In formula (a2-1),
L ^a3 represents -O- or *-O-(CH ₂ ) _k2 -CO-O-,
k2 represents any integer from 1 to 7; * represents a bonding site with -CO-.
R ^a14 represents a hydrogen atom or a methyl group.
R ^a15 and R ^a16 each independently represent a hydrogen atom, a methyl group or a hydroxy group.
o1 represents an integer from 0 to 10;

In formula (a2-1), L ^a3 is preferably -O-, -O-(CH ₂ ) _f1 -CO-O- (f1 represents an integer of 1 to 4) , more preferably -O-.
R ^a14 is preferably a methyl group.
R ^a15 is preferably a hydrogen atom.
R ^a16 is preferably a hydrogen atom or a hydroxy group.
o1 is preferably any integer from 0 to 3, more preferably 0 or 1.

Examples of the structural unit (a2-1) include structural units derived from monomers described in JP-A-2010-204646. Structural units represented by any one of formulas (a2-1-1) to (a2-1-6) are preferred, and any one of formulas (a2-1-1) to (a2-1-4) Structural units represented by formula (a2-1-1) or formula (a2-1-3) are more preferable.

When the resin (A) contains the structural unit (a2-1), its content is usually 1 to 45 mol%, preferably 1 to 40 mol%, based on the total structural units of the resin (A). Yes, more preferably 1 to 35 mol %, still more preferably 2 to 20 mol %, still more preferably 2 to 10 mol %.

<Structural unit (a3)>
The lactone ring of the structural unit (a3) may be a monocyclic ring such as a β-propiolactone ring, γ-butyrolactone ring, δ-valerolactone ring, or a condensed ring of a monocyclic lactone ring and another ring. It's okay. Preferable examples include a γ-butyrolactone ring, an adamantanelactone ring, or a bridged ring containing a γ-butyrolactone ring structure (for example, a structural unit represented by the following formula (a3-2)).

［式（ａ３－１）、式（ａ３－２）、式（ａ３－３）及び式（ａ３－４）中、
Ｌ^ａ４、Ｌ^ａ５及びＬ^ａ６は、それぞれ独立に、－Ｏ－又は＊－Ｏ－（ＣＨ_２）_ｋ３－ＣＯ－Ｏ－（ｋ３は１～７のいずれかの整数を表す。）で表される基を表す。
Ｌ^ａ７は、－Ｏ－、＊－Ｏ－Ｌ^ａ８－Ｏ－、＊－Ｏ－Ｌ^ａ８－ＣＯ－Ｏ－、＊－Ｏ－Ｌ^ａ８－ＣＯ－Ｏ－Ｌ^ａ９－ＣＯ－Ｏ－又は＊－Ｏ－Ｌ^ａ８－Ｏ－ＣＯ－Ｌ^ａ９－Ｏ－を表す。
Ｌ^ａ８及びＬ^ａ９は、それぞれ独立に、炭素数１～６のアルカンジイル基を表す。
＊はカルボニル基との結合部位を表す。
Ｒ^ａ１８、Ｒ^ａ１９及びＲ^ａ２０は、それぞれ独立に、水素原子又はメチル基を表す。
Ｒ^ａ２４は、ハロゲン原子を有していてもよい炭素数１～６のアルキル基、水素原子又はハロゲン原子を表す。
Ｒ^ａ２１は炭素数１～４の脂肪族炭化水素基を表す。
Ｒ^ａ２２、Ｒ^ａ２３及びＲ^ａ２５は、それぞれ独立に、カルボキシ基、シアノ基又は炭素数１～４の脂肪族炭化水素基を表す。
Ｘ^ａ３は、－ＣＨ_２－又は酸素原子を表す。
ｐ１は０～５のいずれかの整数を表す。
ｑ１は、０～３のいずれかの整数を表す。
ｒ１は、０～３のいずれかの整数を表す。
ｗ１は、０～８のいずれかの整数を表す。
ｐ１、ｑ１、ｒ１及び／又はｗ１が２以上のとき、複数のＲ^ａ２１、Ｒ^ａ２２、Ｒ^ａ２３及び／又はＲ^ａ２５は互いに同一であってもよく、異なっていてもよい。］ Structural unit (a3) is preferably a structural unit represented by formula (a3-1), formula (a3-2), formula (a3-3) or formula (a3-4). One of these may be contained alone, or two or more may be contained.

[In formula (a3-1), formula (a3-2), formula (a3-3) and formula (a3-4),
L ^a4 , L ^a5 and L ^a6 are each independently represented by —O— or *—O—(CH ₂ ) _k3 —CO—O— (k3 represents an integer of 1 to 7); represents a group.
L ^a7 is -O-, *-OL ^a8 -O-, *-OL ^a8 -CO-O-, *-OL ^a8 -CO-OL ^a9 -CO-O- or * -OL ^a8 -O-CO-L ^a9 -O-.
L ^a8 and L ^a9 each independently represent an alkanediyl group having 1 to 6 carbon atoms.
* represents a bonding site with a carbonyl group.
R ^a18 , R ^a19 and R ^a20 each independently represent a hydrogen atom or a methyl group.
R ^a24 represents an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, a hydrogen atom or a halogen atom.
R ^a21 represents an aliphatic hydrocarbon group having 1 to 4 carbon atoms.
R ^a22 , R ^a23 and R ^a25 each independently represent a carboxy group, a cyano group or an aliphatic hydrocarbon group having 1 to 4 carbon atoms.
X ^a3 represents —CH ₂ — or an oxygen atom.
p1 represents any integer from 0 to 5;
q1 represents an integer of 0 to 3;
r1 represents an integer of 0 to 3;
w1 represents any integer from 0 to 8;
When p1, q1, r1 and/or w1 are 2 or more, a plurality of R ^a21 , R ^a22 , R ^a23 and/or R ^a25 may be the same or different. ]

Examples of the aliphatic hydrocarbon group for R ^a21 , R ^a22 , R ^a23 and R ^a25 include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group and tert-butyl group. be done.
Halogen atoms in R ^a24 include fluorine, chlorine, bromine and iodine atoms.
Examples of the alkyl group for R ^a24 include methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, pentyl group and hexyl group, preferably having 1 to 4 carbon atoms. and more preferably a methyl group or an ethyl group.
The alkyl group having a halogen atom for R ^a24 includes a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group, and a perfluoro A hexyl group, a trichloromethyl group, a tribromomethyl group, a triiodomethyl group and the like can be mentioned.

The alkanediyl group for L ^a8 and L ^a9 includes methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5 -diyl group, hexane-1,6-diyl group, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1, 4-diyl group, 2-methylbutane-1,4-diyl group and the like.

（式中、Ｒ^ａ２４、Ｌ^ａ７は、上記と同じ意味を表す。） In formulas (a3-1) to (a3-3), L ^a4 to L ^a6 are each independently preferably —O— or *—O—(CH ₂ ) _k3 —CO—O—, k3 is an integer of 1 to 4, more preferably -O- and *-O-CH ₂ -CO-O-, more preferably an oxygen atom.
R ^a18 to R ^a21 are preferably methyl groups.
R ^a22 and R ^a23 are each independently preferably a carboxy group, a cyano group or a methyl group.
p1, q1 and r1 are each independently preferably an integer of 0 to 2, more preferably 0 or 1.
In formula (a3-4), R ^a24 is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, a methyl group or an ethyl group, still more preferably a hydrogen atom or a methyl group is.
R ^a25 is preferably a carboxy group, a cyano group or a methyl group.
L ^a7 is preferably -O- or *-O-L ^a8 -CO-O-, more preferably -O-, -O-CH ₂ -CO-O- or -O-C ₂ H ₄ - It is CO—O—.
w1 is preferably an integer from 0 to 2, more preferably 0 or 1.
In particular, formula (a3-4) is preferably formula (a3-4)'.

(In the formula, R ^a24 and L ^a7 have the same meanings as above.)

As the structural unit (a3), the monomer described in JP-A-2010-204646, the monomer described in JP-A-2000-122294, the structure derived from the monomer described in JP-A-2012-41274 units. As the structural unit (a3), formula (a3-1-1), formula (a3-1-2), formula (a3-2-1), formula (a3-2-2), formula (a3-3- 1), a structural unit represented by any one of formulas (a3-3-2) and formulas (a3-4-1) to (a3-4-12), and in said structural unit, formula (a3-1 ) to R ^a18 , R ^a19 , R ^a20 and R ^a24 in formulas (a3-4) are preferably structural units in which methyl groups are replaced with hydrogen atoms.

When the resin (A) contains the structural unit (a3), the total content is usually 5 to 70 mol%, preferably 10 to 65 mol%, based on the total structural units of the resin (A). , more preferably 10 to 60 mol %, still more preferably 20 to 55 mol %, particularly preferably 30 to 50 mol %.
Further, the content of structural unit (a3-1), structural unit (a3-2), structural unit (a3-3) or structural unit (a3-4) is is preferably 5 to 60 mol %, more preferably 5 to 50 mol %, even more preferably 10 to 50 mol %.

［式（ａ４）中、
Ｒ⁴¹は、水素原子又はメチル基を表す。
Ｒ⁴²は、炭素数１～２４のハロゲン原子を有する飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ₂－は、－Ｏ－又は－ＣＯに置き換わっていてもよい。］
Ｒ⁴²で表される飽和炭化水素基は、鎖式飽和炭化水素基及び単環又は多環の脂環式飽和炭化水素基、並びに、これらを組み合わせることにより形成される基等が挙げられる。 <Structural unit (a4)>
Structural units (a4) include the following structural units.

[In formula (a4),
R ⁴¹ represents a hydrogen atom or a methyl group.
R ⁴² represents a saturated hydrocarbon group having a halogen atom of 1 to 24 carbon atoms, and --CH ₂ -- contained in the saturated hydrocarbon group may be replaced with --O-- or --CO. ]
The saturated hydrocarbon group represented by R ⁴² includes chain saturated hydrocarbon groups, monocyclic or polycyclic saturated alicyclic hydrocarbon groups, and groups formed by combining these groups.

組み合わせにより形成される基としては、１以上のアルキル基又は１以上のアルカンジイル基と、１以上の脂環式飽和炭化水素基とを組み合わせることにより形成される基が挙げられ、－アルカンジイル基－脂環式飽和炭化水素基、－脂環式飽和炭化水素基－アルキル基、－アルカンジイル基－脂環式飽和炭化水素基－アルキル基等が挙げられる。 Chain saturated hydrocarbon groups include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, decyl group, dodecyl group, pentadecyl group, hexadecyl group, heptadecyl group and octadecyl group. is mentioned. The monocyclic or polycyclic saturated alicyclic hydrocarbon group includes cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group; decahydronaphthyl group, adamantyl group, norbornyl group and the following polycyclic alicyclic saturated hydrocarbon groups such as groups (* represents a bonding site).

Groups formed by combination include groups formed by combining one or more alkyl groups or one or more alkanediyl groups and one or more alicyclic saturated hydrocarbon groups, and -alkanediyl groups Examples include - alicyclic saturated hydrocarbon group, - alicyclic saturated hydrocarbon group - alkyl group, - alkanediyl group - alicyclic saturated hydrocarbon group - alkyl group, and the like.

［式（ａ４－０）中、
Ｒ⁵⁴は、水素原子又はメチル基を表す。
Ｌ^4ａは、単結合又は炭素数１～４のアルカンジイル基を表す。
Ｌ^3ａは、炭素数１～８のペルフルオロアルカンジイル基又は炭素数３～１２のペルフルオロシクロアルカンジイル基を表す。
Ｒ⁶⁴は、水素原子又はフッ素原子を表す。］ The structural unit (a4) is at least selected from the group consisting of formula (a4-0), formula (a4-1), formula (a4-2), formula (a4-3) and formula (a4-4) Structural units represented by one are exemplified.

[In the formula (a4-0),
^R54 represents a hydrogen atom or a methyl group.
L ^4a represents a single bond or an alkanediyl group having 1 to 4 carbon atoms.
L ^3a represents a perfluoroalkanediyl group having 1 to 8 carbon atoms or a perfluorocycloalkanediyl group having 3 to 12 carbon atoms.
^R64 represents a hydrogen atom or a fluorine atom. ]

The alkanediyl group for L ^4a includes linear alkanediyl groups such as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl, ethane-1,1-diyl, branched alkanediyl groups such as propane-1,2-diyl group, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group and 2-methylpropane-1,2-diyl group; be done.

The perfluoroalkanediyl group for L ^3a includes a difluoromethylene group, a perfluoroethylene group, a perfluoroethylfluoromethylene group, a perfluoropropane-1,3-diyl group, a perfluoropropane-1,2-diyl group, and a perfluoropropane-2,2 -diyl group, perfluorobutane-1,4-diyl group, perfluorobutane-2,2-diyl group, perfluorobutane-1,2-diyl group, perfluoropentane-1,5-diyl group, perfluoropentane-2,2 -diyl group, perfluoropentane-3,3-diyl group, perfluorohexane-1,6-diyl group, perfluorohexane-2,2-diyl group, perfluorohexane-3,3-diyl group, perfluoroheptane-1,7 -diyl group, perfluoroheptane-2,2-diyl group, perfluoroheptane-3,4-diyl group, perfluoroheptane-4,4-diyl group, perfluorooctane-1,8-diyl group, perfluorooctane-2,2 -diyl group, perfluorooctane-3,3-diyl group, perfluorooctane-4,4-diyl group and the like.
The perfluorocycloalkanediyl group for L ^3a includes a perfluorocyclohexanediyl group, a perfluorocyclopentanediyl group, a perfluorocycloheptanediyl group, a perfluoroadamantanediyl group, and the like.

L ^4a is preferably a single bond, a methylene group or an ethylene group, more preferably a single bond or a methylene group.
L ^3a is preferably a C 1-6 perfluoroalkanediyl group, more preferably a C 1-3 perfluoroalkanediyl group.

Examples of the structural unit (a4-0) include structural units shown below and structural units in which the methyl group corresponding to R ⁵⁴ in the structural unit (a4-0) in the following structural units is replaced with a hydrogen atom.

［式（ａ４－１）中、
Ｒ^a41は、水素原子又はメチル基を表す。
Ｒ^a42は、置換基を有していてもよい炭素数１～２０の飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ａ^a41は、置換基を有していてもよい炭素数１～６のアルカンジイル基又は式（ａ－ｇ１）で表される基を表す。ただし、Ａ^ａ４１及びＲ^ａ４２のうち少なくとも１つは、置換基としてハロゲン原子（好ましくはフッ素原子）を有する。

〔式（ａ－ｇ１）中、
ｓは０又は１を表す。
Ａ^a42及びＡ^a44は、それぞれ独立に、置換基を有していてもよい炭素数１～５の２価の飽和炭化水素基を表す。
Ａ^a43は、単結合又は置換基を有していてもよい炭素数１～５の２価の飽和炭化水素基を表す。
Ｘ^a41及びＸ^a42は、それぞれ独立に、－Ｏ－、－ＣＯ－、－ＣＯ－Ｏ－又は－Ｏ－ＣＯ－を表す。
ただし、Ａ^a42、Ａ^a43、Ａ^a44、Ｘ^a41及びＸ^a42の炭素数の合計は７以下である。〕
＊は結合部位であり、右側の＊が－Ｏ－ＣＯ－Ｒ^a42との結合部位である。］

[In formula (a4-1),
R ^a41 represents a hydrogen atom or a methyl group.
R ^a42 represents an optionally substituted saturated hydrocarbon group having 1 to 20 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group is replaced with —O— or —CO— may
A ^a41 represents an optionally substituted alkanediyl group having 1 to 6 carbon atoms or a group represented by formula (a-g1). However, at least one of A ^a41 and R ^a42 has a halogen atom (preferably a fluorine atom) as a substituent.

[In formula (a-g1),
s represents 0 or 1;
A ^a42 and A ^a44 each independently represent an optionally substituted divalent saturated hydrocarbon group having 1 to 5 carbon atoms.
A ^a43 represents a single bond or an optionally substituted C 1-5 divalent saturated hydrocarbon group.
X ^a41 and X ^a42 each independently represent -O-, -CO-, -CO-O- or -O-CO-.
However, the total number of carbon atoms of A ^a42 , A ^a43 , A ^a44 , X ^a41 and X ^a42 is 7 or less. ]
* is a binding site, and * on the right side is a binding site with --O--CO--R ^a42 . ]

Examples of saturated hydrocarbon groups for R ^a42 include chain hydrocarbon groups, monocyclic or polycyclic alicyclic hydrocarbon groups, and groups formed by combining these groups.

組み合わせにより形成される基としては、１以上のアルキル基又は１以上のアルカンジイル基と、１以上の脂環式炭化水素基とを組み合わせることにより形成される基が挙げられ、－アルカンジイル基－脂環式炭化水素基、－脂環式炭化水素基－アルキル基、－アルカンジイル基－脂環式炭化水素基－アルキル基等が挙げられる。 Chain hydrocarbon groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl groups. mentioned. Monocyclic or polycyclic alicyclic hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl; decahydronaphthyl, adamantyl, norbornyl and the following groups (* represents a bond) and other polycyclic alicyclic hydrocarbon groups.

Groups formed by combination include groups formed by combining one or more alkyl groups or one or more alkanediyl groups and one or more alicyclic hydrocarbon groups, and -alkanediyl groups- Alicyclic hydrocarbon group, -alicyclic hydrocarbon group-alkyl group, -alkanediyl group-alicyclic hydrocarbon group-alkyl group and the like.

［式（ａ－ｇ３）中、
Ｘ^a43は、酸素原子、カルボニル基、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊はＲ^a42との結合部位を表す。）。
Ａ^a45は、ハロゲン原子を有していてもよい炭素数１～１７の飽和炭化水素基を表す。
＊は結合部位を表す。］
ただし、Ｒ^a42－Ｘ^a43－Ａ^a45において、Ｒ^a42がハロゲン原子を有しない場合は、Ａ^a45は、少なくとも１つのハロゲン原子を有する炭素数１～１７の飽和炭化水素基を表す。 Examples of the substituent that R ^a42 may have include at least one selected from the group consisting of halogen atoms and groups represented by formulas (a-g3). A halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, preferably a fluorine atom.

[In the formula (a-g3),
X ^a43 represents an oxygen atom, a carbonyl group, *--O--CO-- or *--CO--O-- (* represents a bonding site with R ^a42 ).
A ^a45 represents a saturated hydrocarbon group having 1 to 17 carbon atoms which may have a halogen atom.
* represents a binding site. ]
However, in R ^a42 -X ^a43 -A ^a45 , when R ^a42 does not have a halogen atom, A ^a45 represents a C 1-17 saturated hydrocarbon group having at least one halogen atom.

The saturated hydrocarbon group for A ^a45 includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl Alkyl groups such as groups;
Monocyclic alicyclic hydrocarbon groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group; and decahydronaphthyl group, adamantyl group, norbornyl group and the following groups (* represents a bond ) and other polycyclic alicyclic hydrocarbon groups.

R ^a42 is preferably a saturated hydrocarbon group which may have a halogen atom, more preferably an alkyl group having a halogen atom and/or a saturated hydrocarbon group having a group represented by formula (a-g3).
When R ^a42 is a saturated hydrocarbon group having a halogen atom, it is preferably a saturated hydrocarbon group having a fluorine atom, more preferably a perfluoroalkyl group or a perfluorocycloalkyl group, still more preferably having 1 to 1 carbon atoms. A perfluoroalkyl group having 6 carbon atoms, particularly preferably a perfluoroalkyl group having 1 to 3 carbon atoms. Perfluoroalkyl groups include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, perfluoroheptyl and perfluorooctyl groups. A perfluorocyclohexyl group etc. are mentioned as a perfluorocycloalkyl group.
When R ^a42 is a saturated hydrocarbon group having a group represented by formula (a-g3), the total carbon number of R ^a42 including the number of carbon atoms contained in the group represented by formula (a-g3) The number is preferably 15 or less, more preferably 12 or less. When it has a group represented by formula (a-g3) as a substituent, the number thereof is preferably one.

［式（ａ－ｇ２）中、
Ａ^a46は、ハロゲン原子を有していてもよい炭素数１～１７の飽和炭化水素基を表す。
Ｘ^a44は、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊はＡ^a46との結合部位を表す。）。
Ａ^a47は、ハロゲン原子を有していてもよい炭素数１～１７の飽和炭化水素基を表す。
ただし、Ａ^a46、Ａ^a47及びＸ^a44の炭素数の合計は１８以下であり、Ａ^a46及びＡ^a47のうち、少なくとも一方は、少なくとも１つのハロゲン原子を有する。
＊はカルボニル基との結合部位を表す。］ When R ^a42 is a saturated hydrocarbon group having a group represented by formula (a-g3), R ^a42 is more preferably a group represented by formula (a-g2).

[In the formula (a-g2),
A ^a46 represents a saturated hydrocarbon group having 1 to 17 carbon atoms which may have a halogen atom.
X ^a44 represents *--O--CO-- or *--CO--O-- (* represents a binding site with A ^a46 ).
A ^a47 represents a saturated hydrocarbon group having 1 to 17 carbon atoms which may have a halogen atom.
However, the total number of carbon atoms of A ^a46 , A ^a47 and X ^a44 is 18 or less, and at least one of A ^a46 and A ^a47 has at least one halogen atom.
* represents a bonding site with a carbonyl group. ]

The saturated hydrocarbon group of A ^a46 preferably has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms.
The saturated hydrocarbon group of A ^a47 preferably has 4 to 15 carbon atoms, more preferably 5 to 12 carbon atoms, and A ^a47 is more preferably a cyclohexyl group or an adamantyl group.

A preferred structure of the group represented by formula (a-g2) is the following structure (* is the bonding site with the carbonyl group).

Alkanediyl group for A ^a41 includes methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group straight-chain alkanediyl groups such as; Branched alkanediyl groups such as 2-methylbutane-1,4-diyl group can be mentioned.
Examples of substituents on the alkanediyl group represented by A ^a41 include a hydroxy group and an alkoxy group having 1 to 6 carbon atoms.
A ^a41 is preferably an alkanediyl group having 1 to 4 carbon atoms, more preferably an alkanediyl group having 2 to 4 carbon atoms, and still more preferably an ethylene group.

The divalent saturated hydrocarbon groups represented by A ^a42 , A ^a43 and A ^a44 in the group represented by the formula (a-g1) include linear or branched alkanediyl groups and monocyclic divalent alicyclic A saturated hydrocarbon group, a divalent saturated hydrocarbon group formed by combining an alkanediyl group and a divalent saturated alicyclic hydrocarbon group, and the like are included. Specifically, methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, 1-methylpropane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group and the like.
Examples of substituents of the divalent saturated hydrocarbon groups represented by A ^a42 , A ^a43 and A ^a44 include a hydroxy group and an alkoxy group having 1 to 6 carbon atoms.
s is preferably zero.

Among the groups represented by the formula (a-g1), examples of groups in which X ^a42 is -O-, -CO-, -CO-O- or -O-CO- include the following groups. In the following examples, * and ** each represent a binding site, and ** is the binding site with --O--CO--R ^a42 .

The structural unit represented by formula (a4-1) includes the structural units shown below and the methyl group corresponding to R ^a41 in the structural unit represented by formula (a4-1) in the following structural units is replaced with a hydrogen atom. Structural units replaced are included.

［式（ａ４－２）中、
Ｒ^f5は、水素原子又はメチル基を表す。
Ｌ⁴⁴は、炭素数１～６のアルカンジイル基を表し、該アルカンジイル基に含まれる－ＣＨ₂－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｒ^f6は、炭素数１～２０のフッ素原子を有する飽和炭化水素基を表す。
ただし、Ｌ⁴⁴及びＲ^f6の合計炭素数の上限は２１である。］

[In formula (a4-2),
R ^f5 represents a hydrogen atom or a methyl group.
L ⁴⁴ represents an alkanediyl group having 1 to 6 carbon atoms, and --CH ₂ -- contained in the alkanediyl group may be replaced with --O-- or --CO--.
R ^f6 represents a saturated hydrocarbon group having 1 to 20 carbon atoms and a fluorine atom.
However, the upper limit of the total carbon number of L ⁴⁴ and R ^f6 is 21. ]

Examples of the C 1-6 alkanediyl group for L ⁴⁴ include the same groups as those exemplified for A ^a41 .
Examples of the saturated hydrocarbon group for R ^f6 include the same groups as those exemplified for R ^a42 .
The alkanediyl having 1 to 6 carbon atoms in L ⁴⁴ is preferably an alkanediyl group having 2 to 4 carbon atoms, more preferably an ethylene group.

Examples of structural units represented by formula (a4-2) include structural units represented by formulas (a4-1-1) to (a4-1-11). A structural unit in which the methyl group corresponding to R ^f5 in the structural unit (a4-2) is replaced with a hydrogen atom is also included as the structural unit represented by the formula (a4-2).

［式（ａ４－３）中、
Ｒ^f7は、水素原子又はメチル基を表す。
Ｌ⁵は、炭素数１～６のアルカンジイル基を表す。
Ａ^f13は、フッ素原子を有していてもよい炭素数１～１８の２価の飽和炭化水素基を表す。
Ｘ^f12は、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊はＡ^f13との結合部位を表す。）。
Ａ^f14は、フッ素原子を有していてもよい炭素数１～１７の飽和炭化水素基を表す。
但し、Ａ^f13及びＡ^f14の少なくとも１つは、フッ素原子を有し、Ｌ⁵、Ａ^f13及びＡ^f14の合計炭素数の上限は２０である。］

[In formula (a4-3),
R ^f7 represents a hydrogen atom or a methyl group.
L ⁵ represents an alkanediyl group having 1 to 6 carbon atoms.
A ^f13 represents a C 1-18 divalent saturated hydrocarbon group which may have a fluorine atom.
X ^f12 represents *--O--CO-- or *--CO--O-- (* represents a binding site with A ^f13 ).
A ^f14 represents a C 1-17 saturated hydrocarbon group which may have a fluorine atom.
However, at least one of A ^f13 and A ^f14 has a fluorine atom, and the upper limit of the total carbon number of L ⁵ , A ^f13 and A ^f14 is 20. ]

Examples of the alkanediyl group for L ⁵ include the same groups as those exemplified for the alkanediyl group for A ^a41 .

The divalent saturated hydrocarbon group which may have a fluorine atom in A ^f13 preferably has a divalent chain saturated hydrocarbon group which may have a fluorine atom and a fluorine atom is a divalent saturated alicyclic hydrocarbon group, more preferably a perfluoroalkanediyl group.
Examples of the divalent chain saturated hydrocarbon group which may have a fluorine atom include alkanediyl groups such as a methylene group, an ethylene group, a propanediyl group, a butanediyl group and a pentanediyl group; a difluoromethylene group, a perfluoroethylene group, perfluoroalkanediyl groups such as perfluoropropanediyl group, perfluorobutanediyl group and perfluoropentanediyl group;
The divalent saturated alicyclic hydrocarbon group which may have a fluorine atom may be either monocyclic or polycyclic. Monocyclic groups include a cyclohexanediyl group, a perfluorocyclohexanediyl group, and the like. Examples of polycyclic groups include an adamantanediyl group, a norbornanediyl group, a perfluoroadamantanediyl group, and the like.

Examples of saturated hydrocarbon groups and optionally fluorine-containing saturated hydrocarbon groups for A ^f14 include groups similar to those exemplified for R ^a42 . Among them, trifluoromethyl group, difluoromethyl group, methyl group, perfluoroethyl group, 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, ethyl group, perfluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, propyl group, perfluorobutyl group, 2,2,3,3,4,4,4-heptafluorobutyl group, 1,1,2,2,3 , 3,4,4-octafluorobutyl group, butyl group, perfluoropentyl group, 2,2,3,3,4,4,5,5,5-nonafluoropentyl group, pentyl group, hexyl group, perfluorohexyl fluorinated alkyl groups such as heptyl, perfluoroheptyl, octyl and perfluorooctyl groups, cyclopropylmethyl, cyclopropyl, cyclobutylmethyl, cyclopentyl, cyclohexyl, perfluorocyclohexyl, adamantyl, adamantyl Methyl group, adamantyldimethyl group, norbornyl group, norbornylmethyl group, perfluoroadamantyl group, perfluoroadamantylmethyl group and the like are preferred.

In formula (a4-3), L ⁵ is preferably an ethylene group.
The divalent saturated hydrocarbon group of A ^f13 is preferably a group containing a chain saturated hydrocarbon group having 1 to 6 carbon atoms and an alicyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and Chain saturated hydrocarbon groups are more preferred.
The saturated hydrocarbon group of A ^f14 is preferably a group containing a chain saturated hydrocarbon group having 3 to 12 carbon atoms and an alicyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and a saturated chain hydrocarbon group having 3 to 10 carbon atoms. Groups containing a hydrocarbon group and an alicyclic saturated hydrocarbon group having 3 to 10 carbon atoms are more preferred. Among them, A ^f14 is preferably a group containing an alicyclic saturated hydrocarbon group having 3 to 12 carbon atoms, more preferably a cyclopropylmethyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group and an adamantyl group. .

Examples of structural units represented by formula (a4-3) include structural units represented by formulas (a4-1′-1) to (a4-1′-11). A structural unit in which the methyl group corresponding to R ^f7 in the structural unit (a4-3) is replaced with a hydrogen atom is also included as the structural unit represented by the formula (a4-3).

［式（ａ４－４）中、
Ｒ^f21は、水素原子又はメチル基を表す。
Ａ^f21は、－（ＣＨ₂）_j1－、－（ＣＨ₂）_j2－Ｏ－（ＣＨ₂）_j3－又は－（ＣＨ₂）_j4－ＣＯ－Ｏ－（ＣＨ₂）_j5－を表す。
ｊ１～ｊ５は、それぞれ独立に、１～６のいずれかの整数を表す。
Ｒ^f22は、フッ素原子を有する炭素数１～１０の飽和炭化水素基を表す。］

[In the formula (a4-4),
R ^f21 represents a hydrogen atom or a methyl group.
A ^f21 represents -(CH ₂ ) _j1 -, -(CH ₂ ) _j2 -O-(CH ₂ ) _j3 - or -(CH ₂ ) _j4 -CO-O-(CH ₂ ) _j5 -.
j1 to j5 each independently represent an integer of 1 to 6;
R ^f22 represents a C 1-10 saturated hydrocarbon group having a fluorine atom. ]

The saturated hydrocarbon group represented by R ^f22 includes the same saturated hydrocarbon group represented by R ^a42 . R ^f22 is preferably an alkyl group having 1 to 10 carbon atoms having a fluorine atom or an alicyclic saturated hydrocarbon group having 1 to 10 carbon atoms having a fluorine atom, and an alkyl group having 1 to 10 carbon atoms having a fluorine atom is preferably More preferred is an alkyl group having 1 to 6 carbon atoms and having a fluorine atom.

In formula (a4-4), A ^f21 is preferably —(CH ₂ ) _j1 —, more preferably an ethylene group or a methylene group, even more preferably a methylene group.

As the structural unit represented by formula (a4-4), for example, in structural units represented by the following structural units and structural units represented by the following formulas, the methyl group corresponding to R ^f21 in structural unit (a4-4) is hydrogen Structural units replaced with atoms are included.

When the resin (A) has the structural unit (a4), the content thereof is preferably 1 to 20 mol%, more preferably 2 to 15 mol%, based on the total structural units of the resin (A), and 3 ~10 mol% is more preferred.

［式（ａ５－１）中、
Ｒ⁵¹は、水素原子又はメチル基を表す。
Ｒ⁵²は、炭素数３～１８の脂環式炭化水素基を表し、該脂環式炭化水素基に含まれる水素原子は炭素数１～８の脂肪族炭化水素基で置換されていてもよい。
Ｌ⁵⁵は、単結合又は炭素数１～１８の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。］ <Structural unit (a5)>
Examples of non-leaving hydrocarbon groups possessed by the structural unit (a5) include groups having linear, branched or cyclic hydrocarbon groups. Among them, the structural unit (a5) is preferably a group having an alicyclic hydrocarbon group.
Examples of the structural unit (a5) include structural units represented by formula (a5-1).

[In formula (a5-1),
^R51 represents a hydrogen atom or a methyl group.
R ⁵² represents an alicyclic hydrocarbon group having 3 to 18 carbon atoms, and a hydrogen atom contained in the alicyclic hydrocarbon group may be substituted with an aliphatic hydrocarbon group having 1 to 8 carbon atoms. .
L ⁵⁵ represents a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O— or —CO— . ]

The alicyclic hydrocarbon group for R ⁵² may be either monocyclic or polycyclic. Examples of monocyclic alicyclic hydrocarbon groups include cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups. Examples of polycyclic alicyclic hydrocarbon groups include adamantyl groups and norbornyl groups.
Aliphatic hydrocarbon groups having 1 to 8 carbon atoms are, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group and 2 - alkyl groups such as ethylhexyl groups.
Alicyclic hydrocarbon groups having a substituent include a 3-hydroxyadamantyl group and a 3-methyladamantyl group.
R ⁵² is preferably an unsubstituted alicyclic hydrocarbon group having 3 to 18 carbon atoms, more preferably an adamantyl group, a norbornyl group or a cyclohexyl group.

The divalent saturated hydrocarbon group for L ⁵⁵ includes a divalent saturated chain hydrocarbon group and a saturated divalent alicyclic hydrocarbon group, preferably a saturated chain divalent hydrocarbon group. .
Examples of divalent chain saturated hydrocarbon groups include alkanediyl groups such as methylene, ethylene, propanediyl, butanediyl and pentanediyl groups.
The bivalent alicyclic saturated hydrocarbon group may be either monocyclic or polycyclic. The monocyclic alicyclic saturated hydrocarbon group includes cycloalkanediyl groups such as cyclopentanediyl group and cyclohexanediyl group. Examples of the polycyclic divalent alicyclic saturated hydrocarbon group include an adamantanediyl group and a norbornanediyl group.

Groups in which —CH ₂ — contained in the divalent saturated hydrocarbon group represented by L ⁵⁵ is replaced with —O— or —CO— include, for example, formulas (L1-1) to (L1-4) and the group represented by In the following formulas, * and ** each represent a bonding site, and * represents a bonding site with an oxygen atom.

式（Ｌ１－１）中、
Ｘ^x1は、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊はＬ^ｘ１との結合部位を表す。）。
Ｌ^x1は、炭素数１～１６の２価の脂肪族飽和炭化水素基を表す。
Ｌ^x2は、単結合又は炭素数１～１５の２価の脂肪族飽和炭化水素基を表す。
ただし、Ｌ^x1及びＬ^x2の合計炭素数は、１６以下である。
式（Ｌ１－２）中、
Ｌ^x3は、炭素数１～１７の２価の脂肪族飽和炭化水素基を表す。
Ｌ^x4は、単結合又は炭素数１～１６の２価の脂肪族飽和炭化水素基を表す。
ただし、Ｌ^x3及びＬ^x4の合計炭素数は、１７以下である。
式（Ｌ１－３）中、
Ｌ^x5は、炭素数１～１５の２価の脂肪族飽和炭化水素基を表す。
Ｌ^x6及びＬ^x7は、それぞれ独立に、単結合又は炭素数１～１４の２価の脂肪族飽和炭化水素基を表す。
ただし、Ｌ^x5、Ｌ^x6及びＬ^x7の合計炭素数は、１５以下である。
式（Ｌ１－４）中、
Ｌ^x8及びＬ^x9は、単結合又は炭素数１～１２の２価の脂肪族飽和炭化水素基を表す。
Ｗ^x1は、炭素数３～１５の２価の脂環式飽和炭化水素基を表す。
ただし、Ｌ^x8、Ｌ^x9及びＷ^x1の合計炭素数は、１５以下である。 Groups in which —CH ₂ — contained in the divalent saturated hydrocarbon group represented by L ⁵⁵ is replaced with —O— or —CO— include, for example, formulas (L1-1) to (L1-4) and the group represented by In the following formulas, * and ** each represent a bonding site, and * represents a bonding site with an oxygen atom.

In formula (L1-1),
X ^x1 represents *-O-CO- or *-CO-O- (* represents a binding site with L ^x1 ).
L ^x1 represents a divalent aliphatic saturated hydrocarbon group having 1 to 16 carbon atoms.
L ^x2 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 15 carbon atoms.
However, the total carbon number of L ^x1 and L ^x2 is 16 or less.
In formula (L1-2),
L ^x3 represents a divalent aliphatic saturated hydrocarbon group having 1 to 17 carbon atoms.
L ^x4 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 16 carbon atoms.
However, the total carbon number of L ^x3 and L ^x4 is 17 or less.
In formula (L1-3),
L ^x5 represents a divalent aliphatic saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^x6 and L ^x7 each independently represent a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 14 carbon atoms.
However, the total carbon number of L ^x5 , L ^x6 and L ^x7 is 15 or less.
In formula (L1-4),
L ^x8 and L ^x9 each represent a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms.
W ^x1 represents a divalent saturated alicyclic hydrocarbon group having 3 to 15 carbon atoms.
However, the total carbon number of L ^x8 , L ^x9 and W ^x1 is 15 or less.

L ^x1 is preferably a C 1-8 divalent aliphatic saturated hydrocarbon group, more preferably a methylene group or an ethylene group.
L ^x2 is preferably a single bond or a C 1-8 divalent aliphatic saturated hydrocarbon group, more preferably a single bond.
L ^x3 is preferably a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^x4 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^x5 is preferably a C 1-8 divalent aliphatic saturated hydrocarbon group, more preferably a methylene group or an ethylene group.
L ^x6 is preferably a single bond or a C 1-8 divalent aliphatic saturated hydrocarbon group, more preferably a methylene group or an ethylene group.
L ^x7 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^x8 is preferably a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, more preferably a single bond or a methylene group.
L ^x9 is preferably a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, more preferably a single bond or a methylene group.
W ^x1 is preferably a divalent saturated alicyclic hydrocarbon group having 3 to 10 carbon atoms, more preferably a cyclohexanediyl group or an adamantanediyl group.

Examples of the group represented by formula (L1-1) include the divalent groups shown below.

Examples of the group represented by formula (L1-2) include groups shown below.

Examples of the group represented by formula (L1-3) include groups shown below.

Examples of the group represented by formula (L1-4) include groups shown below.

L ⁵⁵ is preferably a single bond or a group represented by formula (L1-1).

樹脂（Ａ）が、構造単位（ａ５）を有する場合、その含有率は、樹脂（Ａ）の全構造単位に対して、１～３０モル％が好ましく、２～２０モル％がより好ましく、３～１５モル％がさらに好ましい。 Examples of the structural unit (a5-1) include the following structural units and structural units in which the methyl group corresponding to R ⁵¹ in the structural unit (a5-1) in the following structural units is replaced with a hydrogen atom.

When the resin (A) has the structural unit (a5), the content thereof is preferably 1 to 30 mol%, more preferably 2 to 20 mol%, based on the total structural units of the resin (A), and 3 ~15 mol% is more preferred.

<Structural unit (II)>
The resin (A) may further contain a structural unit that is decomposed by exposure to generate an acid (hereinafter sometimes referred to as "structural unit (II)"). Examples include structural units described in JP 2016-79235 A, a structural unit having a sulfonate group or a carboxylate group and an organic cation in a side chain or a structural unit having a sulfonio group and an organic anion in a side chain. is preferably

［式（ＩＩ－２－Ａ’）中、
Ｘ^ＩＩＩ３は、炭素数１～１８の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水素基に含まれる水素原子は、ハロゲン原子、ハロゲン原子を有していてもよい炭素数１～６のアルキル基又はヒドロキシ基で置き換わっていてもよい。
Ａ^ｘ１は、炭素数１～８のアルカンジイル基を表し、該アルカンジイル基に含まれる水素原子は、フッ素原子又は炭素数１～６のペルフルオロアルキル基で置換されていてもよい。
ＲＡ^－は、スルホナート基又はカルボキシレート基を表す。
Ｒ^ＩＩＩ３は、水素原子、ハロゲン原子又はハロゲン原子を有していてもよい炭素数１～６のアルキル基を表す。
ＺＡ^＋は、有機カチオンを表す。］ A structural unit having a sulfonate group or carboxylate group and an organic cation in a side chain is preferably a structural unit represented by formula (II-2-A').

[In the formula (II-2-A '),
X ^III3 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O—, —S— or —CO— A hydrogen atom contained in the saturated hydrocarbon group may be replaced with a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, or a hydroxy group.
A ^x1 represents an alkanediyl group having 1 to 8 carbon atoms, and a hydrogen atom contained in the alkanediyl group may be substituted with a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms.
^RA- represents a sulfonate group or a carboxylate group.
R ^III3 represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
ZA ⁺ represents an organic cation. ]

Halogen atoms represented by R ^III3 include fluorine, chlorine, bromine and iodine atoms.
The alkyl group having 1 to 6 carbon atoms and optionally having a halogen atom represented by R ^III3 includes an alkyl group having 1 to 6 carbon atoms and optionally having a halogen atom represented by R ^a8 . The same can be mentioned.
The alkanediyl group having 1 to 8 carbon atoms represented by A ^x1 includes methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group and pentane-1,5-diyl group. , hexane-1,6-diyl group, ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2, 4-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, 2-methylbutane-1,4-diyl group, etc. mentioned.

Examples of the divalent saturated hydrocarbon group having 1 to 18 carbon atoms represented by X ^III3 include a linear or branched alkanediyl group and a monocyclic or polycyclic divalent alicyclic saturated hydrocarbon group. and may be a combination of these.
Specifically, methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1 ,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group , dodecane-1,12-diyl group and other linear alkanediyl groups; butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group , pentane-1,4-diyl group, 2-methylbutane-1,4-diyl group and other branched alkanediyl groups; cyclobutane-1,3-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1 ,4-diyl group, cycloalkanediyl group such as cyclooctane-1,5-diyl group; norbornane-1,4-diyl group, norbornane-2,5-diyl group, adamantane-1,5-diyl group, adamantane Divalent polycyclic alicyclic saturated hydrocarbon groups such as -2,6-diyl group and the like can be mentioned.

Examples of saturated hydrocarbon groups in which —CH ₂ — is replaced with —O—, —S— or —CO— include divalent groups represented by formulas (X1) to (X53). mentioned. However, -CH ₂ - contained in the saturated hydrocarbon group has 17 or less carbon atoms before being replaced with -O-, -S- or -CO-. In the formula below, * and ** represent binding sites, and * represents a binding site with ^Ax1 .

X ³ represents a divalent saturated hydrocarbon group having 1 to 16 carbon atoms.
X ⁴ represents a divalent saturated hydrocarbon group having 1 to 15 carbon atoms.
X ⁵ represents a divalent saturated hydrocarbon group having 1 to 13 carbon atoms.
X ⁶ represents a divalent saturated hydrocarbon group having 1 to 14 carbon atoms.
X ⁷ represents a trivalent saturated hydrocarbon group having 1 to 14 carbon atoms.
X ⁸ represents a divalent saturated hydrocarbon group having 1 to 13 carbon atoms.

Examples of the organic cation represented by ZA ⁺ include those similar to the cation Z1 ⁺ in the acid generator (B1).

［式（ＩＩ－２－Ａ）中、Ｒ^ＩＩＩ３、Ｘ^ＩＩＩ３及びＺＡ^＋は、上記と同じ意味を表す。
ｚは、０～６のいずれかの整数を表す。
Ｒ^ＩＩＩ２及びＲ^ＩＩＩ４は、それぞれ独立して、水素原子、フッ素原子又は炭素数１～６のペルフルオロアルキル基を表し、ｚが２以上のとき、複数のＲ^ＩＩＩ２及びＲ^ＩＩＩ４は互いに同一であってもよいし、異なっていてもよい。
Ｑ^ａ及びＱ^ｂは、それぞれ独立して、フッ素原子又は炭素数１～６のペルフルオロアルキル基を表す。］ The structural unit represented by formula (II-2-A') is preferably a structural unit represented by formula (II-2-A).

[In formula (II-2-A), R ^III3 , X ^III3 and ZA ⁺ have the same meanings as above.
z represents any integer from 0 to 6;
R ^III2 and R ^III4 each independently represent a hydrogen atom, a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms, and when z is 2 or more, a plurality of R ^III2 and R ^III4 are the same may be different.
Q ^a and Q ^b each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group. ]

Examples of the perfluoroalkyl group having 1 to 6 carbon atoms represented by R ^III2 , R ^III4 , Q ^a and Q ^b include the same perfluoroalkyl groups having 1 to 6 carbon atoms represented by Q ^b1 described above. .

［式（ＩＩ－２－Ａ－１）中、
Ｒ^ＩＩＩ２、Ｒ^ＩＩＩ３、Ｒ^ＩＩＩ４、Ｑ^a、Ｑ^b、ｚ及びＺＡ^＋は、上記と同じ意味を表す。
Ｒ^ＩＩＩ５は、炭素数１～１２の飽和炭化水素基を表す。
Ｘ^Ｉ2は、炭素数１～１１の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水素基に含まれる水素原子は、ハロゲン原子又はヒドロキシ基で置換されていてもよい。］ The structural unit represented by formula (II-2-A) is preferably a structural unit represented by formula (II-2-A-1).

[In formula (II-2-A-1),
R ^III2 , R ^III3 , R ^III4 , Q ^a , Q ^b , z and ZA ⁺ have the same meanings as above.
R ^III5 represents a saturated hydrocarbon group having 1 to 12 carbon atoms.
X ^I2 represents a divalent saturated hydrocarbon group having 1 to 11 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O—, —S— or —CO—. A hydrogen atom contained in the saturated hydrocarbon group may be substituted with a halogen atom or a hydroxy group. ]

Examples of saturated hydrocarbon groups having 1 to 12 carbon atoms represented by R ^III5 include methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, Linear or branched alkyl groups such as heptyl group, octyl group, nonyl group, decyl group, undecyl group and dodecyl group can be mentioned.
The divalent saturated hydrocarbon group represented by X ^I2 includes the same divalent saturated hydrocarbon groups as those represented by X ^III3 .

［式（ＩＩ－２－Ａ－２）中、Ｒ^ＩＩＩ３、Ｒ^ＩＩＩ５及びＺＡ^＋は、上記と同じ意味を表す。
ｍ及びｎは、それぞれ独立に、１又は２を表す。］ As the structural unit represented by formula (II-2-A-1), a structural unit represented by formula (II-2-A-2) is preferable.

[In formula (II-2-A-2), R ^III3 , R ^III5 and ZA ⁺ have the same meanings as above.
m and n each independently represent 1 or 2; ]

The structural unit represented by formula (II-2-A′) includes, for example, the following structural units and structural units described in International Publication No. 2012/050015. ZA ⁺ represents an organic cation.

［式（ＩＩ－１－１）中、
Ａ^ＩＩ１は、単結合又は２価の連結基を表す。
Ｒ^ＩＩ１は、炭素数６～１８の２価の芳香族炭化水素基を表す。
Ｒ^ＩＩ２及びＲ^ＩＩ３は、それぞれ独立して、炭素数１～１８の炭化水素基を表し、Ｒ^ＩＩ２及びＲ^ＩＩ３は互いに結合してそれらが結合する硫黄原子とともに環を形成していてもよい。
Ｒ^ＩＩ４は、水素原子、ハロゲン原子又はハロゲン原子を有していてもよい炭素数１～６のアルキル基を表す。
Ａ^－は、有機アニオンを表す。］
Ｒ^ＩＩ１で表される炭素数６～１８の２価の芳香族炭化水素基としては、フェニレン基及びナフチレン基等が挙げられる。
Ｒ^ＩＩ２及びＲ^ＩＩ３で表される炭化水素基としては、Ｒ^ａ３’で表される炭化水素基と同じものが挙げられる。
Ｒ^ＩＩ４で表されるハロゲン原子としては、フッ素原子、塩素原子、臭素原子及びヨウ素原子等が挙げられる。
Ｒ^ＩＩ４で表されるハロゲン原子を有していてもよい炭素数１～６のアルキル基としては、Ｒ^ａ８で表されるハロゲン原子を有していてもよい炭素数１～６のアルキル基と同じものが挙げられる。
Ａ^ＩＩ１で表される２価の連結基としては、例えば、炭素数１～１８の２価の飽和炭化水素基が挙げられ、該２価の飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－又は－ＣＯ－で置き換わっていてもよい。具体的には、Ｘ^ＩＩＩ３で表される炭素数１～１８の２価の飽和炭化水素基と同じものが挙げられる。 A structural unit having a sulfonio group and an organic anion in a side chain is preferably a structural unit represented by formula (II-1-1).

[In the formula (II-1-1),
^AII1 represents a single bond or a divalent linking group.
R ^II1 represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.
R ^II2 and R ^II3 each independently represent a hydrocarbon group having 1 to 18 carbon atoms, and R ^II2 and R ^II3 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.
R ^II4 represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
A ⁻ represents an organic anion. ]
Examples of the divalent aromatic hydrocarbon group having 6 to 18 carbon atoms represented by R ^II1 include a phenylene group and a naphthylene group.
The hydrocarbon groups represented by R ^II2 and R ^II3 include the same hydrocarbon groups as those represented by R ^a3′ .
Halogen atoms represented by ^RII4 include fluorine, chlorine, bromine and iodine atoms.
The alkyl group having 1 to 6 carbon atoms which may have a halogen atom represented by R ^II4 includes an alkyl group having 1 to 6 carbon atoms which may have a halogen atom represented by R ^a8 . The same can be mentioned.
The divalent linking group represented by A ^II1 includes, for example, a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and —CH ₂ — contained in the divalent saturated hydrocarbon group is -O-, -S- or -CO- may be substituted. Specific examples thereof include the same divalent saturated hydrocarbon groups having 1 to 18 carbon atoms represented by X ^III3 .

Examples of structural units containing cations in formula (II-1-1) include structural units represented below.

Organic anions represented by A ⁻ include sulfonate anions, sulfonylimide anions, sulfonylmethide anions and carboxylate anions. The organic anion represented by A ⁻ is preferably a sulfonate anion, and the sulfonate anion is more preferably an anion contained in the salt represented by the above formula (B1).

Sulfonylimide anions represented by A ⁻ include the following.

Sulfonylmethide anions include the following.

Carboxylate anions include the following.

Examples of structural units represented by formula (II-1-1) include structural units represented below.

When the resin (A) contains the structural unit (II), the content of the structural unit (II) is preferably 1 to 20 mol% of the total structural units of the resin (A), and more It is preferably 2 to 15 mol %, more preferably 3 to 10 mol %.

Resin (A) may have structural units other than the structural units described above, and examples of such structural units include structural units well known in the art.

Resin (A) is preferably a resin composed of structural unit (a1) and structural unit (s), that is, a copolymer of monomer (a1) and monomer (s).
Structural unit (a1) is preferably a group consisting of structural unit (a1-0), structural unit (a1-1) and structural unit (a1-2) (preferably the structural unit having a cyclohexyl group and a cyclopentyl group) is at least one selected from, more preferably at least two.
Structural unit (s) is preferably at least one selected from the group consisting of structural unit (a2) and structural unit (a3). Structural unit (a2) is preferably a structural unit represented by formula (a2-1). Structural unit (a3) is preferably a group consisting of a structural unit represented by formula (a3-1), a structural unit represented by formula (a3-2) and a structural unit represented by formula (a3-4) is at least one selected from

Each structural unit that constitutes the resin (A) may be used alone or in combination of two or more, and is produced by a known polymerization method (e.g., radical polymerization method) using a monomer that leads to these structural units. be able to. The content of each structural unit in the resin (A) can be adjusted by adjusting the amount of monomer used for polymerization.
The weight average molecular weight of the resin (A) is preferably 2,000 or more (more preferably 2,500 or more, still more preferably 3,000 or more) and 50,000 or less (more preferably 30,000 or less, further preferably is 15,000 or less). As used herein, the weight average molecular weight is a value obtained by gel permeation chromatography under the conditions described in Examples.

<Resins other than resin (A)>
Examples of the resin other than the resin (A) include a resin containing the structural unit (a4) or the structural unit (a5) (hereinafter sometimes referred to as resin (X)).

As the resin (X), among others, a resin containing the structural unit (a4) is preferable.
In the resin (X), the content of the structural unit (a4) is preferably 30 mol% or more, more preferably 40 mol% or more, based on the total of all structural units of the resin (X). , more preferably 45 mol % or more.
Structural units that the resin (X) may further include structural units (a1), structural units (a2), structural units (a3), and structural units derived from other known monomers. Among them, the resin (X) is preferably a resin consisting only of the structural unit (a4) and/or the structural unit (a5), more preferably a resin consisting only of the structural unit (a4).

Each structural unit that constitutes the resin (X) may be used alone or in combination of two or more. Using a monomer that induces these structural units, the resin (X) is produced by a known polymerization method (e.g., radical polymerization method). can do. The content of each structural unit in the resin (X) can be adjusted by adjusting the amount of the monomer used for polymerization.
The weight average molecular weights of resin (X) are each independently preferably 6,000 or more (more preferably 7,000 or more) and 80,000 or less (more preferably 60,000 or less). The means for measuring the weight-average molecular weight of resin (X) is the same as for resin (A).
Further, when the resist composition contains the resin (X), its content is preferably 1 to 60 parts by mass, more preferably 1 to 50 parts by mass, relative to 100 parts by mass of the resin (A). , More preferably 1 to 40 parts by mass, particularly preferably 1 to 30 parts by mass, particularly preferably 1 to 8 parts by mass.

The content of the resin (A) in the resist composition is preferably 80% by mass or more and 99% by mass or less, more preferably 90% by mass or more and 99% by mass or less, relative to the solid content of the resist composition. Further, when a resin other than the resin (A) is included, the total content of the resin (A) and the resin other than the resin (A) is 80% by mass or more and 99% by mass with respect to the solid content of the resist composition. It is preferably less than or equal to 90% by mass or more, and more preferably 90% by mass or more and 99% by mass or less. The solid content and resin content of the resist composition can be measured by known analytical means such as liquid chromatography or gas chromatography.

<Solvent (E)>
The content of the solvent (E) in the resist composition is usually 90% by mass or more and 99.9% by mass or less, preferably 92% by mass or more and 99% by mass or less, more preferably 94% by mass or more and 99% by mass. % or less. The content of the solvent (E) can be measured by known analytical means such as liquid chromatography or gas chromatography.
Examples of the solvent (E) include glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate and propylene glycol monomethyl ether acetate; glycol ethers such as propylene glycol monomethyl ether; ethyl lactate, butyl acetate, amyl acetate and ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; cyclic esters such as γ-butyrolactone; One kind of the solvent (E) may be used alone, or two or more kinds may be used.

<Quencher (C)>
Examples of the quencher (C) include basic nitrogen-containing organic compounds and salts that generate an acid that is weaker in acidity than the acid generated from the acid generator (B). The content of the quencher (C) is preferably about 0.01 to 5% by mass based on the solid content of the resist composition.
Basic nitrogen-containing organic compounds include amines and ammonium salts. Amines include aliphatic amines and aromatic amines. Aliphatic amines include primary, secondary and tertiary amines.
Amines include 1-naphthylamine, 2-naphthylamine, aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, tri heptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine, methyldinonylamine, methyldidecylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine, tri isopropanolamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4'-diamino-1,2-diphenylethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3 , 3′-diethyldiphenylmethane, 2,2′-methylenebisaniline, imidazole, 4-methylimidazole, pyridine, 4-methylpyridine, 1,2-di(2-pyridyl)ethane, 1,2-di(4- pyridyl)ethane, 1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene, 1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy ) ethane, di(2-pyridyl) ketone, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide, 2,2′-dipyridylamine, 2,2′-dipicolylamine, bipyridine and the like, Aromatic amines such as diisopropylaniline are preferred, and 2,6-diisopropylaniline is more preferred.
Ammonium salts include tetramethylammonium hydroxide, tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, phenyltrimethylammonium hydroxide, 3-(trifluoromethyl)phenyltrimethyl ammonium hydroxide, tetra-n-butylammonium salicylate and choline;

The acidity of a salt that generates an acid weaker than the acid generated from the acid generator (B) is indicated by the acid dissociation constant (pKa). The salt that generates an acid weaker in acidity than the acid generated from the acid generator (B) has an acid dissociation constant of -3<pKa, preferably -1<. Salts with pKa<7, more preferably salts with 0<pKa<5.
Examples of the salt that generates an acid weaker in acidity than the acid generated from the acid generator (B) include salts represented by the following formula, and salts represented by the formula (D) described in JP-A-2015-147926. (Hereinafter, it may be referred to as "weak acid inner salt (D)".), and JP-A-2012-229206, JP-A-2012-6908, JP-A-2012-72109, JP-A-2011-39502. and salts described in JP-A-2011-191745. The salt that generates an acid weaker in acidity than the acid generated from the acid generator (B) is preferably a weak acid inner salt (D).

The weak acid inner salt (D) includes the following salts.

When the resist composition contains the quencher (C), the content of the quencher (C) is usually 0.01 to 5% by mass, preferably 0.01 to 5% by mass, based on the solid content of the resist composition. It is 3% by mass.

<Other ingredients>
If necessary, the resist composition of the present invention may contain components other than the components described above (hereinafter sometimes referred to as "other components (F)"). Other components (F) are not particularly limited, and additives known in the field of resists, such as sensitizers, dissolution inhibitors, surfactants, stabilizers, dyes, etc., can be used.

<Preparation of resist composition>
The resist composition of the present invention comprises a salt (I), a resin (A), and, if necessary, an acid generator (B), a resin other than the resin (A), a solvent (E), and a quencher (C). and other components (F). The mixing order is arbitrary and not particularly limited. The temperature during mixing can be appropriately selected from 10 to 40° C. depending on the type of resin or the like and the solubility of the resin or the like in the solvent (E). An appropriate mixing time can be selected from 0.5 to 24 hours depending on the mixing temperature. The mixing means is also not particularly limited, and stirring and mixing can be used.
After mixing each component, it is preferable to filter using a filter having a pore size of about 0.003 to 0.2 μm.

<Method for producing resist pattern>
The method for producing a resist pattern of the present invention comprises:
(1) a step of applying the resist composition of the present invention onto a substrate;
(2) a step of drying the applied composition to form a composition layer;
(3) exposing the composition layer;
(4) heating the exposed composition layer; and (5) developing the heated composition layer.
The coating of the resist composition on the substrate can be carried out using a commonly used device such as a spin coater. Examples of substrates include inorganic substrates such as silicon wafers. Before applying the resist composition, the substrate may be washed, and an antireflection film or the like may be formed on the substrate.
By drying the applied composition, the solvent is removed and a composition layer is formed. Drying is carried out, for example, by evaporating the solvent using a heating device such as a hot plate (so-called pre-baking), or by using a decompression device. The heating temperature is preferably 50 to 200° C., and the heating time is preferably 10 to 180 seconds. Moreover, the pressure for drying under reduced pressure is preferably about 1 to 1.0×10 ⁵ Pa.
The resulting composition layer is usually exposed using an exposure machine. The exposure machine may be an immersion exposure machine. As the exposure light source, a KrF excimer laser (wavelength: 248 nm), an ArF excimer laser (wavelength: 193 nm), an _F2 excimer laser (wavelength: 157 nm) that emits a laser beam in the ultraviolet region, a solid-state laser source (YAG or semiconductor laser etc.) and emits harmonic laser light in the far ultraviolet region or vacuum ultraviolet region by wavelength conversion, electron beam, and extreme ultraviolet light (EUV). can be done. In the present specification, these irradiations with radiation may be collectively referred to as "exposure". During exposure, exposure is usually performed through a mask corresponding to the desired pattern. When the exposure light source is an electron beam, exposure may be performed by direct drawing without using a mask.
The exposed composition layer is subjected to a heat treatment (so-called post-exposure bake) in order to promote the deprotection reaction at the acid-labile groups. The heating temperature is usually about 50 to 200°C, preferably about 70 to 150°C.
The composition layer after heating is usually developed using a developer using a developing device. The developing method includes a dipping method, a paddle method, a spraying method, a dynamic dispensing method, and the like. The development temperature is preferably, for example, 5 to 60° C., and the development time is preferably, for example, 5 to 300 seconds. A positive resist pattern or a negative resist pattern can be produced by selecting the type of developer as follows.
When producing a positive resist pattern from the resist composition of the present invention, an alkaline developer is used as the developer. The alkaline developer may be any of various alkaline aqueous solutions used in this field. Examples thereof include aqueous solutions of tetramethylammonium hydroxide and (2-hydroxyethyl)trimethylammonium hydroxide (commonly known as choline). The alkaline developer may contain a surfactant.
After development, the resist pattern is preferably washed with ultrapure water, and then water remaining on the substrate and pattern is removed.
When producing a negative resist pattern from the resist composition of the present invention, a developer containing an organic solvent (hereinafter sometimes referred to as "organic developer") is used as the developer.
Examples of organic solvents contained in the organic developer include ketone solvents such as 2-hexanone and 2-heptanone; glycol ether ester solvents such as propylene glycol monomethyl ether acetate; ester solvents such as butyl acetate; glycols such as propylene glycol monomethyl ether. ether solvents; amide solvents such as N,N-dimethylacetamide; aromatic hydrocarbon solvents such as anisole;
The content of the organic solvent in the organic developer is preferably 90% by mass or more and 100% by mass or less, more preferably 95% by mass or more and 100% by mass or less, and still more preferably substantially only the organic solvent.
Among them, as the organic developer, a developer containing butyl acetate and/or 2-heptanone is preferable. The total content of butyl acetate and 2-heptanone in the organic developer is preferably 50% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and substantially contains butyl acetate and/or 2-heptanone. - more preferably only heptanone.
The organic developer may contain a surfactant. In addition, the organic developer may contain a trace amount of water.
During development, the development may be stopped by replacing the organic developer with a solvent of a different type.
It is preferable to wash the resist pattern after development with a rinsing liquid. The rinse liquid is not particularly limited as long as it does not dissolve the resist pattern, and a solution containing a general organic solvent can be used, preferably an alcohol solvent or an ester solvent.
After cleaning, it is preferable to remove the rinse liquid remaining on the substrate and pattern.

<Application>
The resist composition of the present invention is a resist composition for KrF excimer laser exposure, a resist composition for ArF excimer laser exposure, a resist composition for electron beam (EB) exposure or a resist composition for EUV exposure, particularly ArF It is suitable as a resist composition for excimer laser exposure and useful for fine processing of semiconductors.

EXAMPLES The present invention will be described more specifically with reference to examples. In the examples, "%" and "parts" representing the content or amount used are based on mass unless otherwise specified.
A weight average molecular weight is the value calculated|required by the gel permeation chromatography. The analysis conditions for gel permeation chromatography are as follows.
Column: TSKgel Multipore HXL-M x 3+guardcolumn (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min
Detector: RI detector Column temperature: 40℃
Injection volume: 100 μl
Molecular weight standard: Standard polystyrene (manufactured by Tosoh Corporation)
The structure of the compound was confirmed by measuring the molecular ion peak using mass spectrometry (LC: Agilent Model 1100, MASS: Agilent Model LC/MSD). In the following examples, the value of this molecular ion peak is indicated by "MASS".

式（Ｉ－２－ａ）で表される塩６．２７部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物１．７８部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物１．１６部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮し、濃縮マスをカラム（シリカゲル６０Ｎ（球状、中性）１００－２１０μｍ；関東化学（株）製、展開溶媒：クロロホルム／メタノール＝１／１）分取することにより、式（Ｉ－２）で表される塩４．２２部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ４２９．２
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３３９．１ Example 1: Synthesis of salt represented by formula (I-2)

6.27 parts of the salt represented by the formula (I-2-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 1.78 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 1.16 parts of the compound represented by formula (I-2-c) was added, stirred at 50°C for 2 hours, and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. The obtained organic layer was concentrated, and the concentrated mass was collected by column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Ltd., developing solvent: chloroform/methanol=1/1). 4.22 parts of the salt represented by the formula (I-2) were obtained.
MASS (ESI (+) Spectrum): M ⁺ 429.2
MASS (ESI (-) Spectrum): M ^- 339.1

式（Ｉ－３－ａ）で表される塩６．１０部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物１．７８部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物１．１６部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮した後、濃縮残渣に、ｔｅｒｔ－ブチルメチルエーテル３０部を加えて、２３℃で３０分間攪拌した後、上澄み液を除去し、濃縮することにより、式（Ｉ－３）で表される塩６．１４部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ４２９．２
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３２３．０ Example 2: Synthesis of salt represented by formula (I-3)

6.10 parts of the salt represented by formula (I-3-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 1.78 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 1.16 parts of the compound represented by formula (I-2-c) was added, stirred at 50°C for 2 hours, and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether was added to the concentrated residue and stirred at 23° C. for 30 minutes. ) are obtained.
MASS (ESI (+) Spectrum): M ⁺ 429.2
MASS (ESI (-) Spectrum): M ^- 323.0

式（Ｉ－７４－ａ）で表される塩５．７８部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物１．７８部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物１．１６部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮し、濃縮マスをカラム（シリカゲル６０Ｎ（球状、中性）１００－２１０μｍ；関東化学（株）製、展開溶媒：クロロホルム／メタノール＝１／１）分取することにより、式（Ｉ－７４）で表される塩５．１１部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ３８１．２
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３３９．１ Example 3: Synthesis of salt represented by formula (I-74)

5.78 parts of the salt represented by the formula (I-74-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 1.78 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 1.16 parts of the compound represented by formula (I-2-c) was added, stirred at 50°C for 2 hours, and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. The obtained organic layer was concentrated, and the concentrated mass was collected by column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Ltd., developing solvent: chloroform/methanol=1/1). 5.11 parts of the salt represented by the formula (I-74) were obtained.
MASS (ESI (+) Spectrum): M ⁺ 381.2
MASS (ESI (-) Spectrum): M ^- 339.1

式（Ｉ－７５－ａ）で表される塩５．６２部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物１．７８部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物１．１６部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮した後、濃縮残渣に、ｔｅｒｔ－ブチルメチルエーテル３０部を加えて、２３℃で３０分間攪拌した後、上澄み液を除去し、濃縮することにより、式（Ｉ－７５）で表される塩５．６８部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ３８１．２
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３２３．０ Example 4: Synthesis of salt represented by formula (I-75)

5.62 parts of the salt represented by the formula (I-75-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 1.78 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 1.16 parts of the compound represented by formula (I-2-c) was added, stirred at 50°C for 2 hours, and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether was added to the concentrated residue and stirred at 23° C. for 30 minutes. ) were obtained.
MASS (ESI (+) Spectrum): M ⁺ 381.2
MASS (ESI (-) Spectrum): M ^- 323.0

式（Ｉ－１２２－ａ）で表される塩５．９４部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物３．５６部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物２．３２部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮し、濃縮マスをカラム（シリカゲル６０Ｎ（球状、中性）１００－２１０μｍ；関東化学（株）製、展開溶媒：クロロホルム／メタノール＝１／１）分取することにより、式（Ｉ－１２２）で表される塩５．９９部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ５３９．３
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３３９．１ Example 5: Synthesis of salt represented by formula (I-122)

5.94 parts of the salt represented by the formula (I-122-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 3.56 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 2.32 parts of the compound represented by formula (I-2-c) was added, and the mixture was stirred at 50°C for 2 hours and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. The obtained organic layer was concentrated, and the concentrated mass was collected by column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Ltd., developing solvent: chloroform/methanol=1/1). 5.99 parts of the salt represented by the formula (I-122) were obtained.
MASS (ESI (+) Spectrum): M ⁺ 539.3
MASS (ESI (-) Spectrum): M ^- 339.1

式（Ｉ－１２３－ａ）で表される塩５．７９部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物３．５６部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物２．３２部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮した後、濃縮残渣に、ｔｅｒｔ－ブチルメチルエーテル３０部を加えて、２３℃で３０分間攪拌した後、上澄み液を除去し、濃縮することにより、式（Ｉ－１２３）で表される塩６．１２部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ５３９．３
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３２３．０ Example 6: Synthesis of salt represented by formula (I-123)

5.79 parts of the salt represented by the formula (I-123-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 3.56 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 2.32 parts of the compound represented by formula (I-2-c) was added, and the mixture was stirred at 50°C for 2 hours and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether was added to the concentrated residue and stirred at 23° C. for 30 minutes. ) are obtained.
MASS (ESI (+) Spectrum): M ⁺ 539.3
MASS (ESI (-) Spectrum): M ^- 323.0

式（Ｉ－１４６－ａ）で表される塩５．８３部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物３．５６部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物２．３２部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮し、濃縮マスをカラム（シリカゲル６０Ｎ（球状、中性）１００－２１０μｍ；関東化学（株）製、展開溶媒：クロロホルム／メタノール＝１／１）分取することにより、式（Ｉ－１４６）で表される塩４．２４部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ５２７．２
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３３９．１ Example 7: Synthesis of salt represented by formula (I-146)

5.83 parts of the salt represented by the formula (I-146-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 3.56 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 2.32 parts of the compound represented by formula (I-2-c) was added, and the mixture was stirred at 50°C for 2 hours and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. The obtained organic layer was concentrated, and the concentrated mass was collected by column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Ltd., developing solvent: chloroform/methanol=1/1). 4.24 parts of the salt represented by the formula (I-146) were obtained.
MASS (ESI (+) Spectrum): M ⁺ 527.2
MASS (ESI (-) Spectrum): M ^- 339.1

式（Ｉ－１４７－ａ）で表される塩５．６７部及びアセトニトリル３０部を混合し、２３℃で３０分間攪拌した。得られた混合物に、式（Ｉ－２－ｂ）で表される化合物３．５６部を添加し、さらに、５０℃で２時間攪拌した。得られた反応混合物に、式（Ｉ－２－ｃ）で表される化合物２．３２部を添加し、さらに、５０℃で２時間攪拌した後、２３℃まで冷却した。得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮し、濃縮マスをカラム（シリカゲル６０Ｎ（球状、中性）１００－２１０μｍ；関東化学（株）製、展開溶媒：クロロホルム／メタノール＝１／１）分取することにより、式（Ｉ－１４７）で表される塩４．８８部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ５２７．２
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３２３．０ Example 8: Synthesis of salt represented by formula (I-147)

5.67 parts of the salt represented by the formula (I-147-a) and 30 parts of acetonitrile were mixed and stirred at 23° C. for 30 minutes. To the obtained mixture, 3.56 parts of the compound represented by formula (I-2-b) was added, and the mixture was further stirred at 50°C for 2 hours. To the resulting reaction mixture, 2.32 parts of the compound represented by formula (I-2-c) was added, and the mixture was stirred at 50°C for 2 hours and then cooled to 23°C. 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23° C. for 30 minutes. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. The obtained organic layer was concentrated, and the concentrated mass was collected by column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Ltd., developing solvent: chloroform/methanol=1/1). 4.88 parts of the salt represented by the formula (I-147) were obtained.
MASS (ESI (+) Spectrum): M ⁺ 527.2
MASS (ESI (-) Spectrum): M ^- 323.0

式（Ｉ－１４６）で表される塩３．３５部及びジメチルホルムアミド１５部との溶液
に、炭酸カリウム０．２７部とヨウ化カリウム０．０３部とを加えて、２３℃で１時間攪拌した。得られた混合溶液に、式（Ｉ－１７０－ａ）で表される化合物１．１０部を加えて、５０℃で２時間攪拌した。得られた反応溶液を２３℃まで冷却し、得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮し、濃縮マスをカラム（シリカゲル６０Ｎ（球状、中性）１００－２１０μｍ；関東化学（株）製、展開溶媒：クロロホルム／メタノール＝１／１）分取することにより、式（Ｉ－１７０）で表される塩２．１２部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ６８３．３
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３３９．１ Example 9: Synthesis of salt represented by formula (I-170)

0.27 parts of potassium carbonate and 0.03 parts of potassium iodide were added to a solution of 3.35 parts of the salt represented by the formula (I-146) and 15 parts of dimethylformamide, and the mixture was stirred at 23°C for 1 hour. bottom. 1.10 parts of the compound represented by the formula (I-170-a) was added to the obtained mixed solution, and the mixture was stirred at 50° C. for 2 hours. The resulting reaction solution was cooled to 23°C, 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23°C for 30 minutes. rice field. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. The obtained organic layer was concentrated, and the concentrated mass was collected by column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Ltd., developing solvent: chloroform/methanol=1/1). 2.12 parts of the salt represented by the formula (I-170) were obtained.
MASS (ESI (+) Spectrum): M ⁺ 683.3
MASS (ESI (-) Spectrum): M ^- 339.1

式（Ｉ－１４７）で表される塩３．２９部及びジメチルホルムアミド１５部との溶液
に、炭酸カリウム０．２７部とヨウ化カリウム０．０３部とを加えて、２３℃で１時間攪拌した。得られた混合溶液に、式（Ｉ－１７０－ａ）で表される化合物１．１０部を加えて、５０℃で２時間攪拌した。得られた反応溶液を２３℃まで冷却し、得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮した後、濃縮残渣に、ｔｅｒｔ－ブチルメチルエーテル３０部を加えて、２３℃で３０分間攪拌した後、上澄み液を除去し、濃縮することにより、式（Ｉ－１７１）で表される塩３．１１部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ６８３．３
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３２３．０ Example 10: Synthesis of Salt Represented by Formula (I-171)

0.27 parts of potassium carbonate and 0.03 parts of potassium iodide were added to a solution of 3.29 parts of the salt represented by the formula (I-147) and 15 parts of dimethylformamide, and the mixture was stirred at 23°C for 1 hour. bottom. 1.10 parts of the compound represented by the formula (I-170-a) was added to the obtained mixed solution, and the mixture was stirred at 50° C. for 2 hours. The resulting reaction solution was cooled to 23°C, 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23°C for 30 minutes. rice field. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether was added to the concentrated residue, and after stirring at 23° C. for 30 minutes, the supernatant was removed and concentrated to obtain formula (I-171 ) are obtained.
MASS (ESI (+) Spectrum): M ⁺ 683.3
MASS (ESI (-) Spectrum): M ^- 323.0

式（Ｉ－１４６－ａ）で表される塩２．２５部及びジメチルホルムアミド１５部との溶液に、炭酸カリウム０．８１部とヨウ化カリウム０．０９部とを加えて、２３℃で１時間攪拌した。得られた混合溶液に、式（Ｉ－１７０－ａ）で表される化合物３．３０部を加えて、５０℃で８時間攪拌した。得られた反応溶液を２３℃まで冷却し、得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮し、濃縮マスをカラム（シリカゲル６０Ｎ（球状、中性）１００－２１０μｍ；関東化学（株）製、展開溶媒：クロロホルム／メタノール＝１／１）分取することにより、式（Ｉ－１９４）で表される塩０．６８部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ７１１．３
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３３９．１ Example 11: Synthesis of Salt Represented by Formula (I-194)

To a solution of 2.25 parts of the salt represented by the formula (I-146-a) and 15 parts of dimethylformamide, 0.81 parts of potassium carbonate and 0.09 parts of potassium iodide were added, and the mixture was stirred at 23°C for 1 hour. Stirred for hours. 3.30 parts of the compound represented by the formula (I-170-a) was added to the obtained mixed solution, and the mixture was stirred at 50° C. for 8 hours. The resulting reaction solution was cooled to 23°C, 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23°C for 30 minutes. rice field. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. The obtained organic layer was concentrated, and the concentrated mass was collected by column (silica gel 60N (spherical, neutral) 100-210 μm; manufactured by Kanto Chemical Co., Ltd., developing solvent: chloroform/methanol=1/1). 0.68 parts of the salt represented by the formula (I-194) was obtained.
MASS (ESI (+) Spectrum): M ⁺ 711.3
MASS (ESI (-) Spectrum): M ^- 339.1

式（Ｉ－１４７－ａ）で表される塩２．１９部及びジメチルホルムアミド１５部との溶液に、炭酸カリウム０．８１部とヨウ化カリウム０．０９部とを加えて、２３℃で１時間攪拌した。得られた混合溶液に、式（Ｉ－１７０－ａ）で表される化合物１．１０部を加えて、５０℃で８時間攪拌した。得られた反応溶液を２３℃まで冷却し、得られた反応混合物に、クロロホルム５０部及び５％シュウ酸水溶液２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。得られた有機層にイオン交換水２０部を加えて２３℃で３０分間攪拌した後、分液して有機層を取り出した。この水洗操作を５回繰り返した。得られた有機層を濃縮した後、濃縮残渣に、ｔｅｒｔ－ブチルメチルエーテル３０部を加えて、２３℃で３０分間攪拌した後、上澄み液を除去し、濃縮することにより、式（Ｉ－１９５）で表される塩０．８９部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ７１１．３
ＭＡＳＳ（ＥＳＩ（－）Ｓｐｅｃｔｒｕｍ）：Ｍ^－ ３２３．０ Example 12: Synthesis of Salt Represented by Formula (I-195)

To a solution of 2.19 parts of the salt represented by the formula (I-147-a) and 15 parts of dimethylformamide, 0.81 parts of potassium carbonate and 0.09 parts of potassium iodide were added, and the mixture was stirred at 23°C for 1 hour. Stirred for hours. 1.10 parts of the compound represented by the formula (I-170-a) was added to the obtained mixed solution, and the mixture was stirred at 50° C. for 8 hours. The resulting reaction solution was cooled to 23°C, 50 parts of chloroform and 20 parts of a 5% aqueous oxalic acid solution were added to the resulting reaction mixture, and the mixture was stirred at 23°C for 30 minutes. rice field. After adding 20 parts of ion-exchanged water to the obtained organic layer and stirring at 23° C. for 30 minutes, the liquid was separated and the organic layer was taken out. This washing operation was repeated 5 times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether was added to the concentrated residue, and after stirring at 23° C. for 30 minutes, the supernatant was removed and concentrated to obtain formula (I-195 ) is obtained.
MASS (ESI (+) Spectrum): M ⁺ 711.3
MASS (ESI (-) Spectrum): M ^- 323.0

Synthesis of Resin Compounds (monomers) used for synthesizing resin (A) are shown below. Hereinafter, these compounds are referred to as "monomer (a1-1-3)" and the like according to their formula numbers.

Synthesis Example 1: Synthesis of Resin A1 As monomers, monomer (a1-1-3), monomer (a1-2-6), monomer (a2-1-1) and monomer (a3-4-2) are used, The molar ratio [monomer (a1-1-3):monomer (a1-2-6):monomer (a2-1-1):monomer (a3-4-2)] was 45:14:2.5:38. 5, and propylene glycol monomethyl ether acetate in an amount 1.5 times the total amount of monomers was added to obtain a solution. To this solution, 1 mol % and 3 mol % of azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were added as initiators to the total amount of monomers, respectively, and these were heated at 73° C. for about 5 hours. bottom. The resulting reaction mixture was poured into a large amount of methanol/water mixed solvent to precipitate the resin, which was filtered. The resulting resin is again dissolved in propylene glycol monomethyl ether acetate, the resulting solution is poured into a methanol/water mixed solvent to precipitate the resin, and the resin is filtered. Resin A1 with a molecular weight of 7.8×10 ³ was obtained with a yield of 69%. This resin A1 has the following structural units.

Synthesis Example 2: Synthesis of Resin X1 Monomer (a5-1-1) and monomer (a4-0-12) were used as monomers, and the molar ratio [monomer (a5-1-1):monomer (a4-0- 12)] were mixed at a ratio of 50:50, and methyl isobutyl ketone was added in an amount of 1.2 times the mass of the total amount of monomers to obtain a solution. To this solution, 3 mol % of azobis(2,4-dimethylvaleronitrile) was added as an initiator with respect to the total amount of monomers, and the mixture was heated at 70° C. for about 5 hours. The resulting reaction mixture was poured into a large amount of methanol/water mixed solvent to precipitate the resin, which was filtered to obtain Resin X1 having a weight average molecular weight of 1.0×10 ⁴ with a yield of 91%. This resin X1 has the following structural units.

<Preparation of resist composition>
As shown in Table 2, a resist composition was prepared by mixing the following components and filtering the resulting mixture through a fluororesin filter having a pore size of 0.2 μm.

ＩＸ－１：特開２０１３－０３５８２９号公報の実施例に従って合成

ＩＸ－２：特開２０１３－０３５８２９号公報の実施例に従って合成

ＩＸ－３：特開２０１２－２３６８１６号公報の実施例に従って合成

＜クエンチャー（Ｃ）＞
Ｄ１：（東京化成工業（株）製）

＜溶剤＞
プロピレングリコールモノメチルエーテルアセテート ２６５部
プロピレングリコールモノメチルエーテル ２０部
２－ヘプタノン ２０部
γ－ブチロラクトン ３．５部 <Resin>
A1, X1: Resin A1, Resin X1
<Salt (I)>
I-2: salt represented by formula (I-2) I-3: salt represented by formula (I-3) I-74: salt represented by formula (I-74) I-75: formula Salt represented by (I-75) I-122: Salt represented by formula (I-122) I-123: Salt represented by formula (I-123) I-146: Formula (I-146) A salt represented by I-147: a salt represented by the formula (I-147) I-170: a salt represented by the formula (I-170) I-171: a salt represented by the formula (I-171) I-194: a salt represented by the formula (I-194) I-195: a salt represented by the formula (I-195) <acid generator (B)>
B1-21: a salt represented by the formula (B1-21) (synthesized according to the examples of JP-A-2012-224611)
B1-22: a salt represented by the formula (B1-22) (synthesized according to the examples of JP-A-2012-224611)

IX-1: synthesized according to the examples of JP-A-2013-035829

IX-2: synthesized according to the examples of JP-A-2013-035829

IX-3: synthesized according to the examples of JP-A-2012-236816

<Quencher (C)>
D1: (manufactured by Tokyo Chemical Industry Co., Ltd.)

<Solvent>
Propylene glycol monomethyl ether acetate 265 parts Propylene glycol monomethyl ether 20 parts 2-heptanone 20 parts γ-butyrolactone 3.5 parts

<Production of resist pattern and its evaluation>
An organic antireflection film composition (ARC-29; manufactured by Nissan Chemical Industries, Ltd.) was applied to a silicon wafer and baked at 205° C. for 60 seconds to form an organic reflective film having a film thickness of 78 nm on the wafer. A protective film was formed. Then, the above resist composition was applied (spin-coated) onto the organic antireflection film so that the film thickness after drying was 85 nm. After coating, the silicon wafer was pre-baked on a direct hot plate at the temperature indicated in the "PB" column of Table 2 for 60 seconds to form a composition layer. A contact hole pattern (hole pitch 90 nm) was formed on a silicon wafer having a composition layer formed thereon, using an ArF excimer stepper for immersion exposure (XT: 1900Gi; manufactured by ASML, NA = 1.35, 3/4 Annular XY polarization). A mask for forming a hole diameter of 55 nm) was used to perform exposure while changing the exposure dose stepwise. Ultrapure water was used as the liquid immersion medium.
After the exposure, post-exposure baking was performed for 60 seconds on a hot plate at the temperature indicated in the "PEB" column of Table 2. Next, the composition layer on the silicon wafer is developed using butyl acetate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a developer by a dynamic dispensing method at 23° C. for 20 seconds to form a negative resist pattern. manufactured.

In the resist pattern obtained after development, the effective sensitivity was defined as the amount of exposure at which the hole diameter formed using the mask was 45 nm.

<CD uniformity (CDU) evaluation>
In the effective sensitivity, the hole diameter of a pattern formed with a mask having a hole diameter of 55 nm was measured 24 times for each hole, and the average value was taken as the average hole diameter of one hole. A standard deviation was determined by using a population of 400 measurement points of the average hole diameter of a pattern formed by a mask with a hole diameter of 55 nm in the same wafer.
Table 3 shows the results. Numerical values in parentheses indicate standard deviations (nm).

比較組成物１～５と比較して、組成物１～１８での標準偏差が小さく、ＣＤ均一性（ＣＤＵ）評価が良好であった。

CD uniformity (CDU) ratings were good with smaller standard deviations for compositions 1-18 compared to comparative compositions 1-5.

INDUSTRIAL APPLICABILITY The salt of the present invention and the resist composition containing the salt can form a resist pattern having excellent CD uniformity (CDU), and are therefore suitable for microfabrication of semiconductors and extremely useful industrially.

Claims (10)

A salt of the formula (I).

[in the formula (I),
R ¹ represents an aromatic hydrocarbon group having 6 to 18 carbon atoms which may have a substituent.
^XA represents a sulfur atom or an iodine atom.
X ¹ represents an optionally substituted aliphatic hydrocarbon group having 1 to 36 carbon atoms, and —CH ₂ — contained in the aliphatic hydrocarbon group is —O—, —S—, — CO- or -SO ₂ - may be substituted. However, at least one hydrogen atom contained in the aliphatic hydrocarbon group is substituted with a group represented by formula (IA).
X When ^A is a sulfur atom, n represents an integer of 1-3 and m represents an integer of 0-2. However, m+n=3.
X When ^A is an iodine atom, n represents 1 or 2 and m represents 0 or 1. However, m+n=2.
When m and n are 2 or more, a plurality of R ¹ and X ¹ may be the same or different.
When n is 2 or more, in the group represented by formula (IA), as long as at least one X 1 is substituted on X ¹ , the remaining X ¹ may be unsubstituted.
A ⁻ represents an organic anion. ]

[In the formula (IA),
L ² represents an optionally substituted hydrocarbon group having 1 to 36 carbon atoms.
R ^A represents a saturated hydrocarbon group having 1 to 12 carbon atoms.
u1 represents an integer of 0 to 2, and when u1 is 2, multiple RAs are ^the same or different.
s1 represents 1 or 2;
t1 represents 0 or 1; However, the sum of s1 and t1 is 1 or 2.
* represents a bond. ] X ¹ is an optionally substituted chain hydrocarbon group having 1 to 6 carbon atoms (-CH ₂ - contained in the chain hydrocarbon group is -O-, -S-, -CO- or —SO ₂ —, provided that at least one hydrogen atom contained in the chain hydrocarbon group is substituted with a group represented by formula (IA)). Item 1. The salt according to item 1. 3. The salt according to claim 1 or 2, wherein ^R1 is a phenyl group optionally having a substituent. The salt according to any one of claims 1 to 3, wherein m is 1. A salt according to any one of claims 1 to 4, wherein A ^- is a sulfonate anion represented by formula (IA).

[In the formula (IA),
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
L ¹ represents a saturated hydrocarbon group having 1 to 24 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon group may be replaced with —O— or —CO—; A hydrogen atom contained in may be substituted with a fluorine atom or a hydroxy group.
Y ¹ represents an optionally substituted methyl group or an optionally substituted alicyclic hydrocarbon group having 3 to 18 carbon atoms, and is included in the alicyclic hydrocarbon group -CH ₂ - may be replaced with -O-, -SO ₂ - or -CO-. ] An acid generator containing the salt according to any one of claims 1 to 5. A resist composition comprising the acid generator according to claim 6 and a resin (A) having an acid-labile group. 8. The resist composition according to claim 7, further comprising a salt that generates an acid weaker in acidity than the acid generated from the acid generator. 9. The resist composition according to claim 7, further comprising a resin (X) containing a structural unit represented by formula (a4).

[In formula (a4),
R ⁴¹ represents a hydrogen atom or a methyl group.
R ⁴² represents a saturated hydrocarbon group having a halogen atom of 1 to 24 carbon atoms, and -CH 2 - contained in the saturated hydrocarbon group may be replaced with _-O- or -CO. ] (1) a step of applying the resist composition according to any one of claims 7 to 9 onto a substrate;
(2) a step of drying the applied composition to form a composition layer;
(3) exposing the composition layer;
(4) heating the composition layer after exposure; and (5) developing the composition layer after heating;
A method of manufacturing a resist pattern comprising: