JP2011051981A - Salt for acid generator, resist composition, and production method for resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a salt which becomes an acid generator which gives a resist composition which shows high resolution, a good form, and good line edge roughness. <P>SOLUTION: The salt is expressed by formula (I-BB). In the formula, Q<SP>1</SP>and Q<SP>2</SP>each denotes F or a perfluoroalkyl group; X<SP>1</SP>denotes a single bond or a divalent saturated hydrocarbon group in which the methylene group in the group may be substituted by -O- or -CO-; Y<SP>1</SP>denotes an aliphatic hydrocarbon group, an alicyclic hydrocarbon group or an aromatic hydrocarbon group, which may have a substituent, and in which the methylene group in these groups may be substituted by -O- or -CO-; A<SP>1</SP>and A<SP>2</SP>each denotes an aliphatic hydrocarbon group or an alicyclic hydrocarbon group or the like which may have a substituent, or A<SP>1</SP>and A<SP>2</SP>together form a ring which may have a substituent; Ar<SP>1</SP>denotes an aromatic hydrocarbon group which may have a substituent; and m<SB>1</SB>and m<SB>2</SB>denote an integer of 0-2; m<SB>3</SB>denotes an integer of 1-3; m<SB>4</SB>denotes an integer of 1-3, where, m<SB>1</SB>+m<SB>2</SB>+m<SB>3</SB>=3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

Patent Document 1 includes 3,5-dimethyl-4-hydroxyphenyldiphenylsulfonium perfluorobutanesulfonate as a salt for an acid generator, and the following monomer (A) and monomer (C) as a resin: 55: A resist composition containing a polymer obtained by charging and polymerizing at a molar ratio of 45 is described.

JP 2003-140344 A

  In the case of a conventional salt, the shape, resolution, and line edge roughness (LER) of a pattern obtained from a resist composition containing the salt may not always be satisfied.

［式（Ｉ−ＢＢ）中、
Ｑ^１及びＱ^２は、互いに独立に、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。
Ｘ^１は、単結合又は炭素数１〜１７の飽和炭化水素基を表し、該飽和炭化水素基に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよい。
Ｙ^１は、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６〜３６の芳香族炭化水素基を表し、該脂肪族炭化水素基、脂環式炭化水素基及び芳香族炭化水素基は、置換基を有していてもよく、該脂肪族炭化水素基及び脂環式炭化水素基に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよい。
Ａ^１及びＡ^２は、互いに独立に、炭素数１〜２０の脂肪族炭化水素基、炭素数３〜２０の脂環式炭化水素基又は炭素数６〜２０の芳香族炭化水素基を表すか、Ａ^１とＡ^２とが一緒になって炭素数３〜２０の環を形成し、該脂肪族炭化水素基、脂環式炭化水素基、芳香族炭化水素基及び環は、置換基を有していてもよい。
Ａｒ^１は、置換基を有していてもよい（ｍ_４＋１）価の炭素数６〜２０の芳香族炭化水素基を表す。
ｍ_１及びｍ_２は、互いに独立に、０〜２の整数を表す。
ｍ_３は、１〜３の整数を表す。ただし、ｍ_１＋ｍ_２＋ｍ_３＝３である。
ｍ_４は、１〜３の整数を表す。］ The present invention includes the following inventions.
[1] A salt represented by the formula (I-BB).

[In the formula (I-BB)
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
X ¹ represents a single bond or a saturated hydrocarbon group having 1 to 17 carbon atoms, and the methylene group contained in the saturated hydrocarbon group may be substituted with an oxygen atom or a carbonyl group.
Y ¹ represents 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 36 carbon atoms, the aliphatic hydrocarbon group, The alicyclic hydrocarbon group and the aromatic hydrocarbon group may have a substituent, and the methylene group contained in the aliphatic hydrocarbon group and the alicyclic hydrocarbon group is substituted with an oxygen atom or a carbonyl group. May be.
Do A ¹ and A ² each independently represent an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms? A ¹ and A ² together form a ring having 3 to 20 carbon atoms, and the aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group and ring have a substituent. You may do it.
Ar ¹ represents an (m ₄ +1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a substituent.
m ₁ and m ₂ each independently represent an integer of 0 to 2.
m ₃ represents an integer of 1 to 3. _However, it is _{m 1 + m 2 + m 3} = 3.
m ₄ represents an integer of 1 to 3. ]

［式（Ｘ^１−１）中、
Ｘ^a１は、単結合又は炭素数１〜１５の飽和炭化水素基を表し、該飽和炭化水素基に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよい。
＊は、−Ｃ（Ｑ^１）（Ｑ^２）−との結合手を表す。］
［５］Ｙ^１が、式（Ｙ^１−１）〜式（Ｙ^１−３）のいずれかで表される基である［１］〜［４］のいずれか記載の塩。

［式（Ｙ^１−１）〜式（Ｙ^１−３）中、
環に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよく、環に含まれる水素原子は、置換されていてもよい。］
［６］上記［１］〜［５］のいずれか記載の塩を含有する酸発生剤。
［７］上記［６］記載の酸発生剤と樹脂とを含有し、
該樹脂は酸に不安定な基を有し、酸の作用によりアルカリ水溶液で溶解し得る樹脂であるレジスト組成物。
［８］さらに塩基性化合物を含有する［７］記載のレジスト組成物。
［９］（１）上記［７］又は［８］記載のレジスト組成物を基板上に塗布する工程、
（２）塗布後の組成物から溶剤を除去して組成物層を形成する工程、
（３）組成物層に露光機を用いて露光する工程、
（４）露光後の組成物層を加熱する工程、
（５）加熱後の組成物層を、現像装置を用いて現像する工程を含むレジストパターンの製造方法。 [2] The salt according to [1], wherein Ar ¹ is a phenylene group.
[3] The salt according to [1] or [2], wherein m ₁ , m ₂ and m ₃ are 1.
[4] ^{X 1} is, salts according to any one of a group represented by the formula ^{(X 1 -1) [1]} ~ [3].

[In the formula (X ¹ -1),
X ^a1 represents a single bond or a saturated hydrocarbon group having 1 to 15 carbon atoms, and the methylene group contained in the saturated hydrocarbon group may be substituted with an oxygen atom or a carbonyl group.
* Represents a bond with —C (Q ¹ ) (Q ² ) —. ]
[5] ^{Y 1} is, salts according to any one of a group represented by any of formulas ^(Y 1 -1) ~ formula ^{(Y 1 -3) [1]} ~ [4].

[In the formula (Y ¹ -1) to the formula (Y ¹ -3),
The methylene group contained in the ring may be substituted with an oxygen atom or a carbonyl group, and the hydrogen atom contained in the ring may be substituted. ]
[6] An acid generator containing the salt according to any one of [1] to [5] above.
[7] It contains an acid generator and a resin as described in [6] above,
A resist composition, which is a resin having an acid labile group and capable of being dissolved in an alkaline aqueous solution by the action of an acid.
[8] The resist composition according to [7], further containing a basic compound.
[9] (1) A step of applying the resist composition according to [7] or [8] on a substrate,
(2) a step of removing the solvent from the composition after coating to form a composition layer;
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) A method for producing a resist pattern, comprising a step of developing the heated composition layer using a developing device.

  According to the salt of the present invention, a pattern having excellent shape, resolution and line edge roughness can be obtained from a resist composition containing the salt.

［式（Ｉ−ＢＢ）中、
Ｑ^１及びＱ^２は、互いに独立に、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。
Ｘ^１は、単結合又は２価の炭素数１〜１７の飽和炭化水素基を表し、該飽和炭化水素基に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよい。
Ｙ^１は、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６〜３６の芳香族炭化水素基を表し、該脂肪族炭化水素基、脂環式炭化水素基及び芳香族炭化水素基は、置換基を有していてもよく、該脂肪族炭化水素基及び脂環式炭化水素基に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよい。
Ａ^１及びＡ^２は、互いに独立に、炭素数１〜２０の脂肪族炭化水素基、炭素数３〜２０の脂環式炭化水素基又は炭素数６〜２０の芳香族炭化水素基を表すか、Ａ^１とＡ^２とが一緒になって炭素数３〜２０の環を形成し、該脂肪族炭化水素基、脂環式炭化水素基、芳香族炭化水素基及び環は、置換基を有していてもよい。
Ａｒ^１は、置換基を有していてもよい（ｍ_４＋１）価の炭素数６〜２０の芳香族炭化水素基を表す。
ｍ_１及びｍ_２は、互いに独立に、０〜２の整数を表す。
ｍ_３は、１〜３の整数を表す。ただし、ｍ_１＋ｍ_２＋ｍ_３＝３である。
ｍ_４は、１〜３の整数を表す。］ The salt of the present invention is represented by the formula (I-BB).

[In the formula (I-BB)
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
X ¹ represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, and the methylene group contained in the saturated hydrocarbon group may be substituted with an oxygen atom or a carbonyl group.
Y ¹ represents 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 36 carbon atoms, the aliphatic hydrocarbon group, The alicyclic hydrocarbon group and the aromatic hydrocarbon group may have a substituent, and the methylene group contained in the aliphatic hydrocarbon group and the alicyclic hydrocarbon group is substituted with an oxygen atom or a carbonyl group. May be.
Do A ¹ and A ² each independently represent an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms? A ¹ and A ² together form a ring having 3 to 20 carbon atoms, and the aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group and ring have a substituent. You may do it.
Ar ¹ represents an (m ₄ +1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a substituent.
m ₁ and m ₂ each independently represent an integer of 0 to 2.
m ₃ represents an integer of 1 to 3. _However, it is _{m 1 + m 2 + m 3} = 3.
m ₄ represents an integer of 1 to 3. ]

In this specification, unless otherwise specified, specific chemical substituents described later can be applied to any chemical structural formula having the same substituents while appropriately selecting the number of carbon atoms. Those which can take any of linear, branched or cyclic are included unless otherwise specified, and in the same group, linear, branched and / or cyclic partial structures are mixed. It may be. When stereoisomers exist, all of those stereoisomers are included.
Further, "(meth) acrylic monomer" means at least one monomer having a structure of "CH ₂ = CH-CO-" or _{"CH 2 = C (CH 3)} -CO- ". 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.

  Examples of perfluoroalkyl groups include perfluoromethyl group, perfluoroethyl group, perfluoro-n-propyl group, perfluoroisopropyl group, perfluoro-n-butyl group, perfluoro-sec-butyl group, perfluoro-tert-butyl group, perfluoro-n- A pentyl group, a perfluoro-n-hexyl group, etc. are mentioned. Of these, a perfluoromethyl group is preferable.

Examples of the divalent saturated hydrocarbon group include divalent groups including an alkylene group and a cycloalkylene group.
Examples of the alkylene group include a methylene group, a dimethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, a nonamethylene group, a decamethylene group, an undecamethylene group, and a dodecamethylene group. , Tridecamethylene group, tetradecamethylene group, pentadecamethylene group, hexadecamethylene group, heptacamethylene group, ethylene group, propylene group, isopropylene group, sec-butylene group, tert-butylene group, propylidene group, etc. Be mentioned

［式（Ｘ^１−Ａ）〜式（Ｘ^１−Ｃ）中、
Ｘ^１Ａ及びＸ^１Ｂは、それぞれ独立に、炭素数１〜６のアルキレン基を表す。ただし、式（Ｘ^１−Ａ）〜式（Ｘ^１−Ｃ）で表される基の炭素数は１〜１７である。］ Examples of the divalent group containing a cycloalkylene group include groups represented by the formula (X ¹ -A) to the formula (X ¹ -C).

[In the formula (X ¹ -A) to formula (X ¹ -C),
X ^1A and X ^1B each independently represent an alkylene group having 1 to 6 carbon atoms. However, the number of carbon atoms of the group represented by the formula ^(X 1 -A) ~ Formula ^(X 1 -C) is 1 to 17. ]

The one or more methylene groups contained in the divalent saturated hydrocarbon group substituted by an oxygen atom or a carbonyl group group, for ^{example, -X 11 -O -, - X} 11 -CO-O -, - X 11 —O—CO—, —X ¹¹ —O—X ¹² — and the like are preferable, —X ¹¹ —O— and —X ¹¹ —CO—O— are preferable, and —X ¹¹ —CO— is more preferable. O- is mentioned.
Here, X < ¹¹ > and X < ¹² > represent a single bond or a C1-C15 alkylene group mutually independently. However, in the group in which the methylene group contained in the alkylene group is substituted, the number of atoms constituting the main chain of each of the above groups is 1 to 17, which is the same as k.

Examples of the aliphatic hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, heptyl. Groups, alkyl groups such as 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, and the like.
Examples of the alicyclic hydrocarbon group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a norbornyl group, a 1-adamantyl group, and a 2-adamantyl group. And a cycloalkyl group such as an isobornyl group.
Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group, a naphthyl group, and an antonyl group.

  Examples of the ring include a heterocyclic ring containing at least one sulfur atom. For example, thiirane, thiane, thiin, thiazoline, iazolidine, oxathiolane and the like can be mentioned.

Examples of the substituent that Y ¹ may have include, for example, a halogen atom, a hydroxyl group, a cyano group, an oxo group, a glycidyloxy group, an acyl group having 2 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, carbon An alkoxycarbonyl group having 1 to 7 carbon atoms or an aliphatic hydrocarbon group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, and 7 to 7 carbon atoms And hydrocarbon groups such as 21 aralkyl groups.

Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group.
As an alkoxy group, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, an n-hexoxy group, a heptoxy group, an octoxy group , 2-ethylhexoxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group and the like.

Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propioxycarbonyl group, an isopropoxycarbonyl group, an n-butoxycarbonyl group, a sec-butoxycarbonyl group, a tert-butoxycarbonyl group, and an n-pentoxycarbonyl group. Etc.
Examples of the aralkyl group include benzyl group, phenethyl group, phenylpropyl group, trityl group, naphthylmethyl group, naphthylethyl group and the like.

Examples of the substituent that A ¹ and A ² may have include, for example, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms that may have a hydroxyl group, an alkoxy group having 1 to 12 carbon atoms, or 4 carbon atoms. -36 alicyclic hydrocarbon is mentioned, The hydrogen atom contained in this alicyclic hydrocarbon group is a halogen atom, a hydroxyl group, a C1-C12 alkyl group, a C1-C12 alkoxy group, carbon The aryl group having 6 to 12 carbon atoms, the aralkyl group having 7 to 12 carbon atoms, the glycidyloxy group, or the acyl group having 2 to 4 carbon atoms may be substituted.
Examples of the alkyl group which may have a hydroxyl group include a hydroxymethyl group and a hydroxyethyl group.

Examples of the substituent that Ar ¹ may have include, for example, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms that may have a hydroxyl group, an alkoxy group having 1 to 12 carbon atoms, or a group having 4 to 36 carbon atoms. An alicyclic hydrocarbon is mentioned, The hydrogen atom contained in this alicyclic hydrocarbon group is a halogen atom, a hydroxyl group, a C1-C12 alkyl group, a C1-C12 alkoxy group, C6-C6. It may be substituted with a 12 aryl group, a C7-12 aralkyl group, a glycidyloxy group or a C2-4 acyl group.

In the salt represented by the formula (I-BB), Q ¹ and Q ² are preferably each independently a fluorine atom or —CF ₃ , and more preferably a fluorine atom.

［式（Ｘ^１−１）中、
Ｘ^a１は、単結合又は炭素数１〜１５の飽和炭化水素基を表し、該飽和炭化水素基に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよい。
＊は、−Ｃ（Ｑ^１）（Ｑ^２）−との結合手を表す。］ X ¹ is preferably a group represented by the formula (X ¹ -1).

[In the formula (X ¹ -1),
X ^a1 represents a single bond or a saturated hydrocarbon group having 1 to 15 carbon atoms, and the methylene group contained in the saturated hydrocarbon group may be substituted with an oxygen atom or a carbonyl group.
* Represents a bond with —C (Q ¹ ) (Q ² ) —. ]

Specific examples of X ¹ include the following groups.

Y ¹ is preferably an alicyclic hydrocarbon group having 3 to 36 carbon atoms which may have a substituent.
Examples of Y ¹ include groups represented by formulas (W1) to (W26).

Y ¹ is a group in which a hydrogen atom contained in Y ¹ is not substituted or substituted only with a hydrocarbon group (provided that a methylene group contained in Y ¹ may be substituted with an oxygen atom) And a group substituted with a hydroxyl group or a group containing a hydroxyl group (excluding those having a lactone structure) and a lactone in which two adjacent methylene groups contained in Y ¹ are substituted with an oxygen atom and a carbonyl group A group having a structure and a group having a ketone structure in which one methylene group contained in Y ¹ is substituted with a carbonyl group, and a hydrogen atom contained in Y ¹ is substituted with an aromatic hydrocarbon group or a group having an aromatic ring And a group having an ether structure in which one methylene group contained in Y ¹ is substituted with an oxygen atom.

［式（Ｙ^１−１）〜式（Ｙ^１−３）中、
環に含まれるメチレン基は酸素原子又はカルボニル基で置換されていてもよく、環に含まれる水素原子は、置換されていてもよい。］
環に含まれる水素原子が置換されていてもよい置換基としては、Ｙ^１の置換基として例示したものが挙げられる。 In particular, Y ¹ is preferably a group represented by any one of formulas (Y ¹ -1) to (Y ¹ -3).

[In the formula (Y ¹ -1) to the formula (Y ¹ -3),
The methylene group contained in the ring may be substituted with an oxygen atom or a carbonyl group, and the hydrogen atom contained in the ring may be substituted. ]
Examples of the substituent in which the hydrogen atom contained in the ring may be substituted include those exemplified as the substituent for Y ¹ .

Examples of Y ¹ include the following groups.

A ¹ and A ² are preferably aromatic hydrocarbon groups, more preferably phenyl groups or naphthyl groups.
Ar ¹ is preferably a phenylene group, and more preferably a p-phenylene group.
m ₁ , m ₂ , m ₃ and m ₄ are preferably 1.

  Examples of the anion of the salt represented by the formula (I-BB) include anions represented by the following formula (IA), formula (IB), formula (IC) or formula (ID). An anion etc. which are represented by (IA) and a formula (IB) are mentioned.

[In formula (IA), formula (IB), formula (IC) and formula (ID),
Q ¹ , Q ² and Y ¹ are the same as defined in formula (I-BB).
X ¹⁰ represents a single bond or an alkylene group having 1 to 15 carbon atoms.
X ¹¹ and X ¹² each independently represent an alkylene group having 1 to 15 carbon atoms. ]

  Examples of the anion include the following.

［式（ＢＢ−ａ１）中、
Ａ^１、Ａ^２、ｍ_１及びｍ_２は、前記と同じ意味を表す。
Ｐ^３３は、互いに独立に、水酸基、水酸基を有していてもよい炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基又は炭素数４〜３６の脂環式炭化水素を表し、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、水酸基、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基、炭素数６〜１２のアリール基、炭素数７〜１２のアラルキル基、グリシジルオキシ基又は炭素数２〜４のアシル基で置換されていてもよい。
ｔは、０〜４の整数である。］ Examples of the cation of the salt represented by the formula (I-BB) include a cation represented by the formula (BB-a1).

[In the formula (BB-a1),
A ¹ , A ² , m ₁ and m ₂ represent the same meaning as described above.
P ³³ represents independently, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms which may have a hydroxyl group, an alicyclic hydrocarbon alkoxy group or a C 4 to 36 from 1 to 12 carbon atoms, The hydrogen atom contained in the alicyclic hydrocarbon group is a halogen atom, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or 7 to 7 carbon atoms. It may be substituted with 12 aralkyl groups, glycidyloxy groups or acyl groups having 2 to 4 carbon atoms.
t is an integer of 0-4. ]

［式（ＢＢ−ａ２）中、
Ｐ^３３及びｔは、前記と同じ意味を表す。
Ｐ^３２及びＰ^３４は、互いに独立に、水酸基、水酸基を有していてもよい炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基又は炭素数４〜３６の脂環式炭化水素を表し、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、水酸基、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基、炭素数６〜１２のアリール基、炭素数７〜１２のアラルキル基、グリシジルオキシ基又は炭素数２〜４のアシル基で置換されていてもよい。
ｓ及びｕは、互いに独立に、０〜５の整数である。］ The cation of the salt represented by the formula (I-BB) is preferably a cation represented by the formula (BB-a2).

[In the formula (BB-a2),
P ³³ and t represent the same meaning as described above.
P ³² and P ³⁴ are each independently a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an alicyclic hydrocarbon having 4 to 36 carbon atoms, which may have a hydroxyl group. The hydrogen atom contained in the alicyclic hydrocarbon group is a halogen atom, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, carbon It may be substituted with an aralkyl group having 7 to 12 carbon atoms, a glycidyloxy group or an acyl group having 2 to 4 carbon atoms.
s and u are integers of 0 to 5 independently of each other. ]

［式（ＢＢ−ａ３）中、Ｐ^３３及びｔは、前記と同じ意味を表す。］ More preferred examples of the cation in the salt represented by the formula (I-BB) include a cation represented by the formula (BB-a3).

[In the formula (BB-a3), P ³³ and t represent the same meaning as described above. ]

Examples of the cation in the salt represented by the formula (I-BB) include the following cations.

  In the salt of this invention, the anion and cation mentioned above can be combined arbitrarily.

  Examples of the salt represented by the formula (I-BB) include salts represented by the formula (I-BB-1 ') to the formula (I-BB-8').

［式（Ｉ−ＢＢ−１’）〜式（Ｉ−ＢＢ−８’）中、
Ｐ^３２、Ｐ^３３、Ｐ^３４、ｓ、ｔ及びｕは、前記と同じ意味を表す。］

[In formula (I-BB-1 ′) to formula (I-BB-8 ′),
P ³² , P ³³ , P ³⁴ , s, t, and u represent the same meaning as described above. ]

中でも、式（Ｉ−ＢＢ−１）〜式（Ｉ−ＢＢ−８）で表される塩が好ましい。 Of the above combinations, the following salts are preferable.

Among these, salts represented by the formula (I-BB-1) to the formula (I-BB-8) are preferable.

溶剤としては、クロロホルム等が挙げられる。
式（Ｉ−ＢＢ−ａ）で表される塩は、例えば、国際公開番号ＷＯ２００５／１０９１０２号に記載された方法に準じて製造することができる。
式（Ｉ−ＢＢ−ｂ）で表される塩は、例えば、特開第２００８−２０９９１７号公報に記載された方法に準じて製造することができる。
The salt (I-BB) can be obtained, for example, by reacting a salt represented by the formula (I-BB-a) with a salt represented by the formula (I-BB-b) in a solvent. .

Examples of the solvent include chloroform.
The salt represented by the formula (I-BB-a) can be produced, for example, according to the method described in International Publication No. WO2005 / 109102.
The salt represented by the formula (I-BB-b) can be produced, for example, according to the method described in JP-A-2008-209917.

  The acid generator of the present invention contains a salt represented by the formula (I-BB). When using the salt represented by a formula (I-BB) as an acid generator, you may use individually or in combination of 2 or more types. The acid generator of the present invention further comprises a known salt other than the salt represented by the formula (I-BB), a cation contained in the salt represented by the formula (I-BB), and a known anion. You may use it in combination with the salt which consists of a salt, the anion contained in the salt represented by a formula (I-BB), and a well-known cation.

式（ＩＸｚ）中、
Ｐ^ａ、Ｐ^ｂ及びＰ^ｃは、互いに独立に、炭素数１〜３０のアルキル基、炭素数３〜３０の脂環式炭化水素基又は炭素数６〜２０の芳香族炭化水素基を表し、該アルキル基に含まれる水素原子は、水酸基、炭素数１〜１２のアルコキシ基又は炭素数３〜１２の環式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又は芳香族炭化水素に含まれる水素原子は、水酸基、ハロゲン原子、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基又は炭素数４〜３６の脂環式炭化水素で置換されていてもよい。
式（ＩＸｂ）中、Ｐ^４及びＰ^５は、互いに独立に、水素原子、水酸基、炭素数１〜１２のアルキル基又は炭素数１〜１２のアルコキシ基を表す。 Examples of the known cation include a cation represented by the formula (IXz), the formula (IXb), the formula (IXc), or the formula (IXd).

In the formula (IXz),
P ^a , P ^b and P ^c each independently represent an alkyl group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms, The hydrogen atom contained in the alkyl group may be substituted with a hydroxyl group, an alkoxy group having 1 to 12 carbon atoms or a cyclic hydrocarbon group having 3 to 12 carbon atoms, and the alicyclic hydrocarbon group or aromatic group. The hydrogen atom contained in the hydrocarbon may be substituted with a hydroxyl group, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an alicyclic hydrocarbon having 4 to 36 carbon atoms. .
In formula (IXb), P ⁴ and P ⁵ each independently represent a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

In formula (IXc),
P ⁶ and P ⁷ each independently represent an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms, or P ⁶ and P ⁷ together represent 3 to 12 carbon atoms. Form a ring.
P ⁸ represents a hydrogen atom, and P ⁹ represents an alkyl group having 1 to 12 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a substituent, or P ⁸ and P ^{8 9} together form a ring having 3 to 12 carbon atoms.

In formula (IXd),
P ¹⁰ to P ²¹ are independently of each other, represent a hydrogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 12 carbon atoms having 1 to 12 carbon atoms.
E represents a sulfur atom or an oxygen atom.
m represents 0 or 1. ]

なかでも、テトラヒドロチオフェニウム基が好ましい。
Ｐ^８における芳香族炭化水素基の置換基としては、炭素数１〜１２のアルキル基等が挙げられる。
Ｐ^８とＰ^９とが互いに結合して環を形成する場合、−ＣＨ（Ｐ^８）−ＣＯ−Ｐ^９基としては、以下の基などが挙げられる。

ここで、＊は硫黄原子との結合手を示す。 The ring formed by P ⁶ and P ⁷ or P ⁸ and P ⁹ together may be either an aromatic or non-aromatic ring.
Examples of the ring formed by combining P ⁶ and P ⁷ with each other include a heterocyclic ring containing at least one sulfur atom. For example, examples of the —S ⁺ (P ⁶ ) (P ⁷ ) group include groups represented by the following.

Of these, a tetrahydrothiophenium group is preferable.
The substituent of the aromatic hydrocarbon group for P ^8, include alkyl groups of 1 to 12 carbon atoms.
When P ⁸ and P ⁹ are bonded to each other to form a ring, examples of the —CH (P ⁸ ) —CO—P ⁹ group include the following groups.

Here, * indicates a bond with a sulfur atom.

Specific examples of the cation represented by the formula (IXz) include the following.

  Specific examples of the cation represented by the formula (IXb) include the followings.

  Specific examples of the cation represented by the formula (IXc) include the followings.

  Specific examples of the cation represented by the formula (IXd) include the followings.

The resist composition of the present invention contains the acid generator described above and a resin.
The resin is a resin having an acid labile group, insoluble or hardly soluble in an alkaline aqueous solution, and soluble in an alkaline aqueous solution by the action of an acid.

  In the resist composition of the present invention, the salt represented by the formula (I-BB), which is an acid generator, generates an acid upon exposure and is catalytic to a group in the resin that is unstable to the acid. To cause the resin to be soluble in an aqueous alkali solution. Such a resist composition is suitable as a chemically amplified positive resist composition.

  Examples of the acid labile group include a group having an alkyl ester in which the carbon atom adjacent to the oxygen atom is a quaternary carbon atom, a group having a carboxylic acid ester such as an alicyclic ester, and a carbon atom adjacent to the oxygen atom. And a group having a lactone ring which is a quaternary carbon atom. Here, the quaternary carbon atom means a carbon atom bonded to a substituent other than a hydrogen atom and not bonded to hydrogen. The acid labile group is preferably a group having a quaternary carbon atom in which a carbon atom adjacent to an oxygen atom of an ether bond is bonded to three carbon atoms.

Acid labile groups, for example, when exemplified as R ester -COOR a group having a carboxylic acid ester (a -COO-C (CH _{3) 3} is referred to as a tert- butyl ester),
an alkyl ester in which the carbon atom adjacent to the oxygen atom represented by tert-butyl ester is a quaternary carbon atom;
Methoxymethyl ester, ethoxymethyl ester, 1-ethoxyethyl ester, 1-isobutoxyethyl ester, 1-isopropoxyethyl ester, 1-ethoxypropyl ester, 1- (2-methoxyethoxy) ethyl ester, 1- (2- Acetoxyethoxy) ethyl ester, 1- [2- (1-adamantyloxy) ethoxy] ethyl ester, 1- [2- (1-adamantanecarbonyloxy) ethoxy] ethyl ester, tetrahydro-2-furyl ester and tetrahydro-2- Acetal-type esters such as pyranyl esters;
The carbon atom adjacent to the oxygen atom such as isobornyl ester, 1-alkyl cycloalkyl ester, 2-alkyl-2-adamantyl ester, 1- (1-adamantyl) -1-alkylalkyl ester is a quaternary carbon atom. Examples include alicyclic esters.

  Examples of the group having a carboxylic acid ester include a group having a (meth) acrylic acid ester, a norbornene carboxylic acid ester, a tricyclodecene carboxylic acid ester, and a tetracyclodecene carboxylic acid ester.

The resin can be produced by addition polymerization of a monomer having an acid labile group and an olefinic double bond.
Such monomers include bulky groups such as alicyclic structures such as 2-alkyl-2-adamantyl groups and 1- (1-adamantyl) -1-alkylalkyl groups as acid labile groups. Monomers are preferred because the resolution of the resulting resist tends to be excellent.

  Specific examples of the monomer containing a bulky group include 2-alkyl-2-adamantyl (meth) acrylate, 1- (1-adamantyl) -1-alkylalkyl (meth) acrylate, and 5-norbornene-2. -2-alkyl-2-adamantyl carboxylate, 1- (1-adamantyl) -1-alkylalkyl 5-norbornene-2-carboxylate, 2-alkyl-2-adamantyl α-chloroacrylate, α-chloroacrylic acid 1- (1-adamantyl) -1-alkylalkyl and the like.

  In particular, when 2-alkyl-2-adamantyl (meth) acrylate or 2-alkyl-2-adamantyl α-chloroacrylate is used as a monomer, it is preferable because the resolution of the resulting resist tends to be excellent.

  Specifically, as 2-alkyl-2-adamantyl (meth) acrylate, for example, 2-methyl-2-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-acrylate Examples include adamantyl, 2-ethyl-2-adamantyl methacrylate, 2-n-butyl-2-adamantyl acrylate, and the like. Examples of the α-chloro-2-alkyl-2-adamantyl α-chloroacrylate include 2-methyl-2-adamantyl α-chloroacrylate, 2-ethyl-2-adamantyl α-chloroacrylate, and the like.

  Among these, when 2-ethyl-2-adamantyl (meth) acrylate or 2-isopropyl-2-adamantyl (meth) acrylate is used, the resulting resist tends to have excellent sensitivity and heat resistance. preferable.

  (Meth) acrylic acid 2-alkyl-2-adamantyl can be usually produced by a reaction of 2-alkyl-2-adamantanol or a metal salt thereof with acrylic acid halide or methacrylic acid halide.

The resin may contain repeating units derived from acid stable monomers. Here, the structure derived from an acid-stable monomer means a structure that is not cleaved by the acid generator of the present invention.
Specifically, a repeating unit derived from a monomer having a free carboxylic acid group such as acrylic acid or methacrylic acid, a repeating unit derived from an aliphatic unsaturated dicarboxylic anhydride such as maleic anhydride or itaconic anhydride , A repeating unit derived from 2-norbornene, a repeating unit derived from (meth) acrylonitrile, an alkyl ester or 1-adamantyl ester in which the carbon atom adjacent to the oxygen atom is a secondary or tertiary carbon atom (meth) Derived from a repeating unit derived from an acrylate ester, a repeating unit derived from a styrene monomer such as p- or m-hydroxystyrene, and a (meth) acryloyloxy-γ-butyrolactone in which the lactone ring may be substituted with an alkyl group And the like. In the 1-adamantyl ester, the carbon atom adjacent to the oxygen atom is a quaternary carbon atom. However, the 1-adamantyl ester is an acid-stable group, and a hydroxyl group or the like may be bonded to the 1-adamantyl ester.

  Specific examples of the acid-stable monomer include 3-hydroxy-1-adamantyl (meth) acrylate, 3,5-dihydroxy-1-adamantyl (meth) acrylate, α- (meth) acryloyloxy-γ-butyrolactone, β- (meth) acryloyloxy-γ-butyrolactone, a monomer that gives a repeating unit represented by the formula (a), a monomer that gives a repeating unit represented by the formula (b), hydroxystyrene, norbornene, etc. Examples thereof include an alicyclic compound having a bond, an aliphatic unsaturated dicarboxylic acid anhydride such as maleic anhydride, and itaconic anhydride.

  Among them, in particular, a repeating unit derived from a styrenic monomer such as p- or m-hydroxystyrene, a repeating unit derived from 3-hydroxy-1-adamantyl (meth) acrylate, (meth) acrylic acid 3,5- A resist obtained from a resin containing any one of a repeating unit derived from dihydroxy-1-adamantyl, a repeating unit represented by the formula (a), and a repeating unit represented by the formula (b) has the following characteristics: This is preferable because the resolution tends to improve.

（式中、Ｒ¹及びＲ²は、互いに独立に、水素原子又はメチル基を表し、Ｒ³及びＲ⁴は、互いに独立に水素原子、メチル基、トリフルオロメチル基又はハロゲン原子を表し、ｉ及びｊは、１〜３の整数を表す。ｉが２または３のときには、Ｒ³は互いに異なる基であってもよく、ｊが２または３のときには、Ｒ⁴は互いに異なる基であってもよい。）

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a methyl group; R ³ and R ⁴ each independently represent a hydrogen atom, a methyl group, a trifluoromethyl group, or a halogen atom; And j represents an integer of 1 to 3. When i is 2 or 3, R ³ may be a different group, and when j is 2 or 3, R ⁴ may be a different group. Good.)

  Monomers such as (meth) acrylic acid 3-hydroxy-1-adamantyl and (meth) acrylic acid 3,5-dihydroxy-1-adamantyl are commercially available. For example, it can also be produced by reacting the corresponding hydroxyadamantane with (meth) acrylic acid or its halide.

  In addition, a monomer such as (meth) acryloyloxy-γ-butyrolactone is obtained by reacting α- or β-bromo-γ-butyrolactone whose lactone ring may be substituted with an alkyl group with acrylic acid or methacrylic acid, or lactone. It can be produced by reacting an α- or β-hydroxy-γ-butyrolactone whose ring may be substituted with an alkyl group with an acrylic acid halide or a methacrylic acid halide.

  Examples of the monomer that gives the repeating unit represented by the formulas (a) and (b) include (meth) acrylic acid esters of alicyclic lactones having the following hydroxyl groups, and mixtures thereof. These esters can be produced, for example, by a reaction between a corresponding alicyclic lactone having a hydroxyl group and (meth) acrylic acid (see, for example, JP-A No. 2000-26446).

  Here, as (meth) acryloyloxy-γ-butyrolactone, for example, α-acryloyloxy-γ-butyrolactone, α-methacryloyloxy-γ-butyrolactone, α-acryloyloxy-β, β-dimethyl-γ-butyrolactone, α- Methacryloyloxy-β, β-dimethyl-γ-butyrolactone, α-acryloyloxy-α-methyl-γ-butyrolactone, α-methacryloyloxy-α-methyl-γ-butyrolactone, β-acryloyloxy-γ-butyrolactone, β- Examples include methacryloyloxy-γ-butyrolactone, β-methacryloyloxy-α-methyl-γ-butyrolactone, and the like.

In the case of KrF excimer laser exposure and EUV exposure, sufficient transmittance can be obtained even when a repeating unit derived from a styrene monomer such as p- or m-hydroxystyrene is used as the resin repeating unit. Such a copolymer resin can be obtained by radically polymerizing the corresponding (meth) acrylic acid ester monomer, acetoxystyrene, and styrene and then deacetylating with an acid.
As a monomer which gives the repeating unit derived from a styrene-type monomer, the following compounds are mentioned, for example.

  Of the above monomers, 4-hydroxystyrene or 4-hydroxy-α-methylstyrene is particularly preferred.

  Moreover, since the resin containing a repeating unit derived from 2-norbornene has an alicyclic skeleton directly in its main chain, it has a strong structure and exhibits excellent dry etching resistance. The repeating unit derived from 2-norbornene can be introduced into the main chain by radical polymerization using, in addition to the corresponding 2-norbornene, an aliphatic unsaturated dicarboxylic anhydride such as maleic anhydride or itaconic anhydride. Therefore, the one formed by opening the double bond of the norbornene structure can be represented by the formula (c), and the one formed by opening the double bond of maleic anhydride and itaconic anhydride is respectively It can represent with Formula (d) and Formula (e).

Here, R ⁵ and R ⁶ in formula (c) are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a carboxyl group, a cyano group, or —COOU (U is an alcohol residue). Or R ⁵ and R ⁶ are bonded to each other to represent a carboxylic anhydride residue represented by —C (═O) OC (═O) —.
When R ⁵ and R ⁶ are a group —COOU, the carboxyl group is an ester group, and the alcohol residue corresponding to U has, for example, about 1 to 8 carbon atoms that may be substituted. And an alkyl group, a 2-oxooxolan-3- or -4-yl group. Here, in the alkyl group, a hydroxyl group, an alicyclic hydrocarbon residue, or the like may be bonded as a substituent.
Specific examples when R ⁵ and R ⁶ are alkyl groups include a methyl group, an ethyl group, and a propyl group. Specific examples of the alkyl group to which a hydroxyl group is bonded include a hydroxymethyl group and 2-hydroxyethyl group. Groups and the like.

Thus, specific examples of the norbornene structure represented by the formula (c), which is a monomer that gives a stable repeating unit to an acid, include the following compounds.
2-norbornene,
2-hydroxy-5-norbornene,
5-norbornene-2-carboxylic acid,
Methyl 5-norbornene-2-carboxylate,
2-hydroxy-1-ethyl 5-norbornene-2-carboxylate,
5-norbornene-2-methanol,
5-norbornene-2,3-dicarboxylic anhydride.

In addition, if U of R ⁵ and R ⁶ —COOU in the formula (c) is an acid labile group such as an alicyclic ester in which the carbon atom adjacent to the oxygen atom is a quaternary carbon atom, Even though it has a norbornene structure, it is a repeating unit having an acid labile group. Examples of the monomer containing a norbornene structure and an acid labile group include, for example, 5-norbornene-2-carboxylic acid-t-butyl, 5-norbornene-2-carboxylic acid 1-cyclohexyl-1-methylethyl, and 5-norbornene. 2-carboxylate 1-methylcyclohexyl, 5-norbornene-2-carboxylic acid 2-methyl-2-adamantyl, 5-norbornene-2-carboxylic acid 2-ethyl-2-adamantyl, 5-norbornene-2-carboxylic acid 1- (4-methylcyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1- (4-hydroxycyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1-methyl-1- (4-Oxocyclohexyl) ethyl, 5-norbornene-2-carboxylic acid 1- (1-adama) Chill) -1-methylethyl and the like.

  Further, the acid-stable group may contain a repeating unit represented by the formula (b1) and a repeating unit containing a fluorine atom.

［式（ｂ１）中、Ｒ^１は、水素原子、メチル基又はトリフルオロメチル基を表す。
ＡＲは、炭素数１〜３０の炭化水素基を表し、該炭化水素基に含まれる水素原子の少なくとも１個以上がフッ素原子に置換されている。該炭化水素基に含まれるメチレン基は、酸素原子、硫黄原子又は−Ｎ（Ｒ^ｃ）−で置換されていてもよく、該炭化水素基に含まれる水素原子は、水酸基又は炭素数１〜６の脂肪族炭化水素基で置換されていてもよい。Ｒ^ｃは、上記と同じ意味を表す。］

[In formula (b1), R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group.
AR represents a hydrocarbon group having 1 to 30 carbon atoms, and at least one hydrogen atom contained in the hydrocarbon group is substituted with a fluorine atom. The methylene group contained in the hydrocarbon group may be substituted with an oxygen atom, a sulfur atom or —N (R ^c ) —, and the hydrogen atom contained in the hydrocarbon group is a hydroxyl group or a carbon number of 1-6. May be substituted with an aliphatic hydrocarbon group. R ^c represents the same meaning as described above. ]

  Specific examples of the monomer that gives the repeating unit represented by the formula (b1) include the following monomers.

  The resin varies depending on the type of radiation for patterning exposure, the type of acid labile group, etc., but the content of repeating units derived from monomers having an acid labile group in the resin is usually 10 to 10. Adjust to the range of 80 mol%.

  As repeating units derived from monomers having acid labile groups, in particular, 2-alkyl-2-adamantyl methacrylate, 2-alkyl-2-adamantyl acrylate 1- (1-adamantyl) -1-alkyl methacrylate In the case of containing a repeating unit derived from alkyl, 2-alkyl-2-adamantyl methacrylate 1- (1-adamantyl) -1-alkylalkyl acrylate, 15 of all repeating units constituting the resin. When it is at least mol%, the resin has an alicyclic group, so that it has a sturdy structure, which is advantageous in terms of dry etching resistance of the resist to be provided.

  When an alicyclic compound having an olefinic double bond in the molecule and an aliphatic unsaturated dicarboxylic acid anhydride are used as monomers, they tend to be difficult to undergo addition polymerization. It is preferable to use in excess.

  As the monomer used, monomers having the same olefinic double bond but different acid labile groups may be used in combination, or monomers having the same acid labile group and different olefinic double bonds may be used in combination. Alternatively, monomers having different combinations of acid-labile groups and olefinic double bonds may be used in combination.

  The weight average molecular weight of the resin is preferably 2,500 or more and 100,000 or less, more preferably 2,700 or more and 50,000 or less, and still more preferably 3,000 or more and 40,000 or less.

  When the composition containing the acid generator and the resin described above is used as a resist composition, a basic compound, preferably a basic nitrogen-containing organic compound, more preferably an amine or ammonium salt is contained. By adding a basic compound as a quencher, it is possible to improve the performance degradation due to the deactivation of the acid accompanying the holding after exposure. Specific examples of the basic compound used for the quencher include those represented by the following formulas.

In the formula, R ¹¹ , R ¹² and R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, The hydrogen atom contained in the alkyl group, cycloalkyl group and aryl group may be substituted with a hydroxyl group, an amino group or an alkoxy group having 1 to 6 carbon atoms, and the hydrogen atom contained in the amino group is a carbon atom. It may be substituted with an alkyl group of formulas 1-4.

R ¹³ and R ¹⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R ¹³ and R ¹⁴ are combined to form an aromatic ring, and the hydrogen atom contained in the alkyl group, cycloalkyl group, aryl group and alkoxy group is a hydroxyl group, an amino group or a carbon number of 1 to 6 may be substituted with an alkoxy group, and the hydrogen atom contained in the amino group may be substituted with an alkyl group having 1 to 4 carbon atoms.

R ¹⁵ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a nitro group. The hydrogen atom contained in the alkyl group, cycloalkyl group, aryl group and alkoxy group may be substituted with a hydroxyl group, an amino group or an alkoxy group having 1 to 6 carbon atoms, and is contained in the amino group. The hydrogen atom to be substituted may be substituted with an alkyl group having 1 to 4 carbon atoms.

R ¹⁶ represents an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and the hydrogen atom contained in the alkyl group and cycloalkyl group is a hydroxyl group, an amino group, or a carbon number 1 to 6 The hydrogen atom contained in the amino group may be substituted with an alkyl group having 1 to 4 carbon atoms.

R ¹⁸ , R ¹⁹ and R ²⁰ each independently represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and the alkyl group or cycloalkyl group And the hydrogen atom contained in the aryl group may be substituted with a hydroxyl group, an amino group, or an alkoxy group having 1 to 6 carbon atoms, and the hydrogen atom contained in the amino group is an alkyl group having 1 to 4 carbon atoms. May be substituted.

  W represents an alkylene group having 2 to 6 carbon atoms, a carbonyl group, an imino group, a sulfide group or a disulfide group.

  Specific examples of such compounds include hexylamine, heptylamine, octylamine, nonylamine, decylamine, aniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, diisopropylaniline, 1- or 2- Naphthylamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diamino-1,2-diphenylethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, 4,4′-diamino-3, 3'-diethyldiphenylmethane, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, N-methylaniline, piperidine, diphenylamine, triethylamine, trimethylamine, tripro Ruamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, 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, triisopropanolamine, N, N-dimethylaniline, 2,6-diisopropylaniline Imidazole, pyridine, 4-methylpyridine, 4-methylimidazole, bipyridine, 2,2′-dipyridylamine, di-2-pyridyl ketone, 1,2-di (2-pyridyl) ethane, 1,2-di (4 -Pyridyl) ethane, 1,3-di (4-pyridyl) propane, 1,2-bis (2-pyridyl) ethylene, 1,2-bis (4-pyridyl) ethylene, 1,2-bis (4-pyridyl) Oxy) ethane, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide, 1,2-bis (4-pyridyl) ethylene, 2,2′-dipiconylamine, 3,3′-dipiconylamine, Tetramethylammonium hydroxide, tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetra-n-hexylammonium Examples thereof include hydroxide, tetra-n-octylammonium hydroxide, phenyltrimethylammonium hydroxide, 3-trifluoromethylphenyltrimethylammonium hydroxide, (2-hydroxyethyl) trimethylammonium hydroxide (common name: choline), and the like. . Of these, diisopropylaniline is preferable.

  Furthermore, a hindered amine compound having a piperidine skeleton as disclosed in JP-A-11-52575 can be used as a quencher.

The resist composition of the present invention preferably contains the resin in the range of about 80 to 99.9% by weight and the acid generator in the range of about 0.1 to 20% by weight based on the total solid content.
Further, when a basic compound that is a quencher is used as the chemically amplified resist composition, it is preferably contained in a range of about 0.01 to 1% by weight based on the total solid content of the resist composition.
The resist composition may further contain small amounts of various additives such as sensitizers, dissolution inhibitors, other resins, surfactants, stabilizers, and dyes as necessary.

  The resist composition of the present invention is usually used as a resist solution composition in a state in which each of the above components is dissolved in a solvent, and is usually used in industrial processes such as spin coating on a substrate such as a silicon wafer. Applied by. The solvent used here may be any solvent that dissolves each component, has an appropriate drying rate, and gives a uniform and smooth coating film after the solvent evaporates, and is usually used industrially in this field. A solvent can be used.

  For example, 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, esters such as ethyl lactate, butyl acetate, amyl acetate and ethyl pyruvate And ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone, and cyclic esters such as γ-butyrolactone. These solvents can be used alone or in combination of two or more.

The method for producing a resist pattern of the present invention comprises:
(1) The process of apply | coating the resist composition of this invention mentioned above on a board | substrate,
(2) a step of removing the solvent from the composition after coating to form a composition layer;
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) The process which develops the composition layer after a heating using a image development apparatus is included.

Application of the resist composition onto the substrate can be performed by a commonly used apparatus such as a spin coater.
The removal of the solvent is performed, for example, by evaporating the solvent using a heating device such as a hot plate or by using a decompression device to form a composition layer from which the solvent has been removed. As for the temperature in this case, about 50-200 degreeC is illustrated, for example. The pressure is exemplified by about 1 to 1.0 × 10 ⁵ Pa.

The obtained composition layer is exposed using an exposure machine. The exposure machine here may be an immersion exposure machine. At the time of exposure, exposure is usually performed through a mask corresponding to a required pattern. The exposure light source emits ultraviolet laser light such as KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F ₂ laser (wavelength 157 nm), solid-state laser light source (YAG or semiconductor laser, etc.) Various types of laser beam can be used, such as those that convert the wavelength of the laser beam from) to radiate a harmonic laser beam in the far ultraviolet region or the vacuum ultraviolet region.

The composition layer after the exposure is subjected to heat treatment for promoting the deprotection group reaction. As heating temperature, it is about 50-200 degreeC normally, Preferably it is about 70-150 degreeC.
The heated composition layer is usually developed using an alkali developer using a developing device. The alkaline developer used here may be various alkaline aqueous solutions used in this field. Examples thereof include an aqueous solution of tetramethylammonium hydroxide and (2-hydroxyethyl) trimethylammonium hydroxide (commonly called choline).
After development, it is preferable to rinse with ultrapure water to remove water remaining on the substrate and the pattern.

  The salt of the present invention is used in a chemically amplified resist composition used for semiconductor microfabrication, and as an acid generator for a resist composition exhibiting high resolution, good shape, and good line edge roughness. Among them, it can be preferably used as an acid generator for resist compositions suitable for excimer laser lithography such as ArF and KrF and ArF immersion exposure lithography.

  Hereinafter, the present invention will be described more specifically with reference to examples. In Examples and Comparative Examples, “%” and “part” representing the content or amount used are based on mass unless otherwise specified.

The weight average molecular weight of the resin is a value determined by gel permeation chromatography using polystyrene as a standard product.
Apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)
Column: 3 TSKgel Multipore HXL-M + guardcolumn (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min
Detector: RI detector Column temperature: 40 ° C
Injection volume: 100 μL
Molecular weight standard: Standard polystyrene (manufactured by Tosoh Corporation)

  The structure of the compound was confirmed by NMR (EX-270 type manufactured by JEOL Ltd.) and mass spectrometry (LC: Agilent 1100 type, MASS: Agilent LC / MSD type or LC / MSD TOF type).

Example 1: Synthesis of salt A1

  To 100 parts of difluoro (fluorosulfonyl) acetic acid methyl ester and 150 parts of ion-exchanged water, 230 parts of a 30% aqueous sodium hydroxide solution was added dropwise in an ice bath. The resulting mixture was refluxed at 100 ° C. for 3 hours, cooled to 23 ° C. and neutralized with 88 parts of concentrated hydrochloric acid. The obtained mixture was concentrated to obtain 164.4 parts of difluorosulfoacetate sodium salt (containing inorganic salt, purity 62.7%). To 1.9 parts (purity 62.7%) of difluorosulfoacetic acid sodium salt and 9.5 parts of N, N-dimethylformamide, 1.0 part of 1,1′-carbonyldiimidazole was added for 2 hours. A mixture was prepared by stirring.

  On the other hand, 0.2 part of sodium hydride was added to 1.1 parts of 3-hydroxyadamantyl methanol and 5.5 parts of N, N-dimethylformamide, and stirred for 2 hours. To this solution was added the above mixture. The resulting mixture was stirred for 15 hours, and the resulting solution containing difluorosulfoacetic acid-3-hydroxy-1-adamantylmethyl ester sodium salt (a salt represented by the formula (I-BB-1-a)) was used as it was. Used for the reaction.

  To a solution containing 1.81 parts of the salt represented by the formula (I-BB-1-a), 3.2 parts of chloroform and 1.57 parts of the salt represented by the formula (I-BB-1-b) are added. Added. The resulting mixture was stirred for 15 hours and washed with ion exchanged water. To the resulting mixture, 1.2 parts of activated carbon was added, stirred and filtered. The obtained filtrate was concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated to obtain 1.22 parts of a salt represented by the formula (I-BB-1) in the form of amber oil. The salt represented by the formula (I-BB-1) was designated as salt A1.

MS (ESI (+) Spectrum): M ⁺ 279.1
MS (ESI (-) Spectrum): M ^- 339.1
¹ H-NMR (dimethylsulfoxide-d ₆ , internal standard substance tetramethylsilane): δ (ppm) 1.35 to 1.80 (m, 12H), 2.10 (m, 2H), 3.31 (brs , 1H), 3.85 (s, 2H), 4.42 (brs, 1H), 7.05-7.14 (m, 2H), 7.65-7.90 (m, 12H)

Example 2: Synthesis of salt A2

To 100 parts of difluoro (fluorosulfonyl) acetic acid methyl ester and 250 parts of ion-exchanged water, 230 parts of a 30% aqueous sodium hydroxide solution was added dropwise in an ice bath. The resulting mixture was refluxed at 100 ° C. for 3 hours, cooled to 23 ° C. and neutralized with 88 parts of concentrated hydrochloric acid. The obtained mixture was concentrated to obtain 164.8 parts of difluorosulfoacetate sodium salt (containing inorganic salt, purity 62.6%). To a mixture of 5.0 parts (purity 62.6%) of the obtained sodium difluorosulfoacetate, 2.6 parts of 4-oxo-1-adamantanol and 100 parts of ethylbenzene, 0.8 part of concentrated sulfuric acid was added, Heated to reflux for hours. The resulting mixture was cooled and filtered, and the resulting filtration residue was washed with tert-butyl methyl ether to give difluorosulfoacetic acid-4-oxo-1-adamantyl ester sodium salt (formula (I-BB-2 The salt represented by -a)) 5.5 parts was obtained.
As a result of purity analysis by ¹ H-NMR, the purity was 35.6%.

  15 parts of acetonitrile and 15 parts of ion-exchanged water were added to 4.86 parts (purity 35.6%) of the salt represented by the formula (I-BB-2-a). Further, 1.57 parts of the salt represented by the formula (I-BB-2-b), 5 parts of acetonitrile and 5 parts of ion-exchanged water were added. The resulting mixture was stirred for 15 hours and concentrated. The organic layer was recovered by extracting the resulting mixture with 50 parts of chloroform. The collected organic layer was washed with ion exchange water. To the organic layer, 1.2 parts of activated carbon was added, stirred and filtered. The obtained filtrate was concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated to obtain 1.88 parts of a salt represented by the formula (I-BB-2) in the form of an amber oil. The salt represented by the formula (I-BB-2) was designated as salt A2.

MS (ESI (+) Spectrum): M ⁺ 279.1
MS (ESI (−) Spectrum): M ⁻ 323.0
¹ H-NMR (dimethylsulfoxide-d ₆ , internal standard substance tetramethylsilane): δ (ppm) 1.72-2.10 (m, 4H), 2.28-2.38 (m, 7H), 2 .50 (s, 2H), 3.31 (brs, 1H), 7.05-7.14 (m, 2H), 7.65-7.90 (m, 12H)

ジフルオロ（フルオロスルホニル）酢酸メチルエステル１００部及びイオン交換水１５０部に、氷浴下、３０％水酸化ナトリウム水溶液２３０部を滴下した。得られた混合物を１００℃で３時間還流し、冷却した。その後、これを濃塩酸８８部で中和した。得られた溶液を濃縮することによりジフルオロスルホ酢酸ナトリウム塩１６４．４部（無機塩含有、純度６２．７％）を得た。得られたジフルオロスルホ酢酸ナトリウム塩３０．０部（純度６２．７％）、ヘキサヒドロ−６−ヒドロキシ−３，５−メタノ−２Ｈ−シクロペンタ〔ｂ〕フラン−２−オン１４．７部及びトルエン３００部を仕込み、さらにｐ−トルエンスルホン酸１８．１部を加え、１２時間加熱還流した。その後、得られた混合物を濾過し、残渣にアセトニトリル１００部を添加し、撹拌した。その溶液を濾過し、得られたろ液を濃縮することにより、式（Ｉ−ＢＢ−３−ａ）で表される塩２６．７部を得た。
^１Ｈ−ＮＭＲによる純度分析の結果、その純度は２８．６％であった。 Example 3: Synthesis of salt A3

To 100 parts of difluoro (fluorosulfonyl) acetic acid methyl ester and 150 parts of ion-exchanged water, 230 parts of a 30% aqueous sodium hydroxide solution was added dropwise in an ice bath. The resulting mixture was refluxed at 100 ° C. for 3 hours and cooled. Thereafter, this was neutralized with 88 parts of concentrated hydrochloric acid. The obtained solution was concentrated to obtain 164.4 parts of sodium difluorosulfoacetate (containing inorganic salt, purity 62.7%). 30.0 parts of obtained difluorosulfoacetic acid sodium salt (purity 62.7%), hexahydro-6-hydroxy-3,5-methano-2H-cyclopenta [b] furan-2-one 14.7 parts and toluene 300 Then, 18.1 parts of p-toluenesulfonic acid was added and heated to reflux for 12 hours. Thereafter, the obtained mixture was filtered, and 100 parts of acetonitrile was added to the residue, followed by stirring. The solution was filtered, and the obtained filtrate was concentrated to obtain 26.7 parts of a salt represented by the formula (I-BB-3-a).
As a result of purity analysis by ¹ H-NMR, the purity was 28.6%.

  20 parts of acetonitrile and 20 parts of ion-exchanged water were added to 5.84 parts (purity 28.6%) of the salt represented by the formula (I-BB-3-a). Further, 1.57 parts of a salt represented by the formula (I-BB-3-b), 5 parts of acetonitrile and 5 parts of ion-exchanged water were added. The resulting mixture was stirred for 15 hours and concentrated. The organic layer was recovered by extracting the resulting mixture with 50 parts of chloroform. The collected organic layer was washed with ion exchange water. To the recovered organic layer, 1.2 parts of activated carbon was added, stirred and filtered. The obtained filtrate was concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated to obtain 0.66 parts of a salt represented by the amber oil-form formula (I-BB-3). The salt represented by the formula (I-BB-3) was designated as salt A3.

MS (ESI (+) Spectrum): M ⁺ 279.1
MS (ESI (-) Spectrum): M ^- 311.0
¹ H-NMR (dimethyl sulfoxide-d ₆ , internal standard substance tetramethylsilane): δ (ppm) 1.57-1.67 (m, 2H), 1.91-2.06 (m, 2H), 2 .53 (m, 2H), 3.21 (m, 1H), 3.31 (brs, 1H), 4.51 (m, 1H), 4.62 (s, 1H), 7.05-7. 14 (m, 2H), 7.65-7.90 (m, 12H)

リチウムアルミニウムハイドライド１０．４部、無水テトラヒドロフラン１２０部を仕込み２３℃で３０分間攪拌した。次いで、式（Ａ４−ａ）で表される塩６２．２部を無水ＴＨＦ９００部に溶かした溶液を氷冷下で滴下し、２３℃で５時間攪拌した。反応マスに酢酸エチル５０．０部、６Ｎ塩酸５０．００部を添加、攪拌後、分液を行った。有機層を濃縮後、カラム（メルク シリカゲル６０−２００メッシュ 展開溶媒：クロロホルム／メタノール＝５／１）分取することにより、式（Ａ４−ｂ）で表される塩を８４．７部（純度６０％）を得た。
式（Ａ４−ｃ）で表される化合物３．５１部、無水ＴＨＦ７５部を仕込み２３℃で３０分間攪拌した。次いで、カルボニルジイミダゾール２．８９部、無水ＴＨＦ５０部の混合溶液を２３℃で滴下し、２３℃で４時間攪拌した。得られた反応液を、式（Ａ４−ｂ）で表される塩６．０４部（純度６０％）、無水ＴＨＦ５０部の混合液中に５４〜６０℃で、２５分間で滴下し、６５℃で１８時間加熱し、冷却後、ろ過した。得られたろ液を濃縮し、濃縮物をカラム（メルク シリカゲル６０−２００メッシュ 展開溶媒：クロロホルム／メタノール＝５／１）分取することにより、式（Ａ４−ｄ）で表される塩２．９９部を得た。

式（Ａ４−ｄ）で表される塩１．０部、クロロホルム３０部を仕込み２３℃で３０分間攪拌した。次いで、式（Ａ４−ｅ）で表される塩０．８７部を２３℃で１２時間攪拌した後、分液を行った。有機層にイオン交換水１０部を添加、分液水洗を行った。この操作を３回行った。得られた有機層に活性炭１．００部を仕込み、２３℃で３０分間攪拌した後、ろ過した。ろ液を濃縮した後、得られた濃縮物に、アセトニトリル２０部を添加して溶解し、濃縮し、酢酸エチル２０部を加えて攪拌し、上澄液を除去した。得られた残渣にｔｅｒｔ−ブチルメチルエーテル２０部を加えて攪拌し、上澄液を除去した。得られた残渣をクロロホルムに溶解し、濃縮した後、得られた濃縮物をカラム（メルク シリカゲル６０−２００メッシュ 展開溶媒：クロロホルム／メタノール＝５／１）分取することにより、式（Ａ４）で表される塩０．６９部を得た。式（Ａ４）で表される塩を塩Ａ４とした。 Example 4: Synthesis of salt A4

10.4 parts of lithium aluminum hydride and 120 parts of anhydrous tetrahydrofuran were charged and stirred at 23 ° C. for 30 minutes. Next, a solution prepared by dissolving 62.2 parts of the salt represented by the formula (A4-a) in 900 parts of anhydrous THF was added dropwise under ice cooling, and the mixture was stirred at 23 ° C. for 5 hours. To the reaction mass, 50.0 parts of ethyl acetate and 50.00 parts of 6N hydrochloric acid were added, followed by liquid separation. After concentrating the organic layer, by separating the column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1), 84.7 parts of salt represented by the formula (A4-b) (purity 60) %).
3.51 parts of a compound represented by the formula (A4-c) and 75 parts of anhydrous THF were charged and stirred at 23 ° C. for 30 minutes. Next, a mixed solution of 2.89 parts of carbonyldiimidazole and 50 parts of anhydrous THF was added dropwise at 23 ° C., and the mixture was stirred at 23 ° C. for 4 hours. The obtained reaction solution was dropped in a mixed solution of 6.04 parts (purity 60%) of the salt represented by the formula (A4-b) and 50 parts of anhydrous THF at 25 to 60 ° C. over 25 minutes, and 65 ° C. For 18 hours, cooled and filtered. The obtained filtrate is concentrated, and the concentrate is fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain a salt 2.99 represented by the formula (A4-d). Got a part.

1.0 part of the salt represented by the formula (A4-d) and 30 parts of chloroform were charged and stirred at 23 ° C. for 30 minutes. Next, 0.87 parts of the salt represented by the formula (A4-e) was stirred at 23 ° C. for 12 hours, and then separated. 10 parts of ion-exchanged water was added to the organic layer, followed by liquid separation washing. This operation was performed three times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. After the filtrate was concentrated, 20 parts of acetonitrile was added to the resulting concentrate to dissolve it, concentrated, 20 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 20 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue is dissolved in chloroform and concentrated, and then the obtained concentrate is fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain the formula (A4). 0.69 parts of the salt represented were obtained. The salt represented by the formula (A4) was designated as salt A4.

MS (ESI (+) Spectrum): M ⁺ 279.1
MS (ESI (-) Spectrum): M ^- 339.1

Synthesis Example: [Synthesis of Resin (B1)]
Monomer (A), monomer (B) and monomer (C) are mixed so that the molar ratio [monomer (A): monomer (B): monomer (C)] is a ratio of 50:25:25. Furthermore, 1.5 mass times dioxane was mixed with respect to the total mass of all monomers. To the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) were added as initiators in proportions of 1 mol% and 3 mol%, respectively, with respect to the total number of moles of all monomers. Then, this was heated at 77 ° C. for about 5 hours to carry out polymerization. Thereafter, the polymerization reaction solution was poured into a large amount of a mixed solvent of methanol and water (mass ratio methanol: water = 4: 1) to precipitate the resin. This resin is filtered and collected, dissolved again in dioxane, poured into a large amount of methanol / water mixed solvent to precipitate the resin, and the precipitated resin is filtered and collected three times for reprecipitation. Purification gave a copolymer having a weight average molecular weight of about 8.0 × 10 ³ in a yield of 60%. This copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin B1.

[Synthesis of Resin B2]
Monomer (A), monomer (E), monomer (B), monomer (C), and monomer (F) are in a molar ratio [monomer (A): monomer (E): monomer (B): monomer (C): The monomer (F)] was mixed at a ratio of 30: 14: 6: 20: 30, and 1.5 mass times dioxane was further mixed with respect to the total mass of all monomers. Into the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were respectively added to 1.00 mol% and 3.00 mol% with respect to the total number of moles of all monomers. Polymerization was carried out by heating at 73 ° C. for about 5 hours. Thereafter, the polymerization reaction solution was poured into a large amount of a mixed solvent of methanol and water (mass ratio methanol: water = 4: 1) to precipitate the resin. This resin is filtered and collected, dissolved again in dioxane, poured into a large amount of methanol / water mixed solvent to precipitate the resin, and the precipitated resin is filtered and collected three times for reprecipitation. Purification gave a copolymer having a weight average molecular weight of about 7.8 × 10 ³ in a yield of 68%. This copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin B2.

[Synthesis of Resin B3]
Monomer (D), monomer (E), monomer (B), monomer (C) and monomer (F) are mixed in a molar ratio [monomer (D): monomer (E): monomer (B): monomer (C): Monomer (F)] is mixed at a ratio of 30: 14: 6: 20: 30, and 1.5 mass times of dioxane is further mixed with this monomer mixture with respect to the total mass of all monomers. did. Into the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were respectively added to 1.00 mol% and 3.00 mol% with respect to the total number of moles of all monomers. Polymerization was carried out by heating at 73 ° C. for about 5 hours. Thereafter, the polymerization reaction solution was poured into a large amount of a mixed solvent of methanol and water (mass ratio methanol: water = 4: 1) to precipitate the resin. This resin is filtered and recovered, dissolved again in dioxane, poured into a large amount of methanol / water mixed solvent to precipitate the resin, and the precipitated resin is filtered and recovered twice to perform reprecipitation. Purification gave a copolymer having a weight average molecular weight of about 8.1 × 10 ³ in a yield of 65%. This copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin B3.

[Synthesis of Resin B4]
Monomer A and monomer C are mixed so that the molar ratio [monomer (A): monomer (C)] is a molar ratio of 55:45, and further 1.5 weight times dioxane of the total monomer amount is added. Added and mixed. To the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) were added as initiators in an amount of 0.9 mol% and 2.7 mol%, respectively, based on the total amount of monomers, and about 70 ° C. Heated for 5 hours. Thereafter, the reaction solution was poured into a large amount of a mixed solvent of methanol and water (mass ratio methanol: water = 4: 1) to cause precipitation. This resin is filtered and recovered, dissolved again in dioxane, poured into a large amount of methanol / water mixed solvent to precipitate the resin, and the precipitated resin is filtered and recovered twice to perform reprecipitation. Purification gave a copolymer having a weight average molecular weight of 1.1 × 10 ^{4 in} a yield of 68%. This copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin B4.

Examples and Comparative Examples As shown in Table 1, a chemically amplified photoresist composition was prepared by filtering a mixture obtained by mixing and dissolving the following components through a fluororesin filter having a pore size of 0.2 μm. A product was prepared.

<Acid generator>
Acid generator C1: 3,5-dimethyl-4-hydroxyphenyldiphenylsulfonium perfluorobutanesulfonate <Basic compound (quencher)>
Basic compound (quencher) Q1: 2,6-diisopropylaniline <Solvent>
Propylene glycol monomethyl ether acetate 265 parts 2-heptanone 20.0 parts Propylene glycol monomethyl ether 20.0 parts γ-butyrolactone 3.5 parts

  An organic antireflective coating composition (ARC-29; manufactured by Nissan Chemical Industries, Ltd.) is applied to a silicon wafer and baked at 205 ° C. for 60 seconds to form an organic antireflective coating having a thickness of 78 nm Formed. Next, the chemical amplification photoresist composition was spin-coated on the organic antireflection film so that the film thickness after drying was 120 nm.

After applying the resist composition, the obtained silicon wafer was pre-baked (PB) for 60 seconds at a temperature described in the “PB” column of Table 1 on a direct hot plate. Using the ArF excimer stepper [FPA5000-AS3; manufactured by Canon Inc., NA = 0.75, 2 / 3Annular] on the silicon wafer on which the film of the chemically amplified photoresist composition is formed in this manner, the exposure amount is stepped. The line-and-space pattern was exposed with various changes.
After exposure, post-exposure baking (PEB) was performed for 60 seconds on a hot plate at the temperature described in the “PEB” column of Table 1, and further with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 60 seconds. Paddle development was performed.

Shape evaluation: Exposure was performed with an exposure amount at which a 100 nm line and space pattern was 1: 1, and the resist pattern was observed with a scanning electron microscope.
A case where the top shape and the skirt shape of the 85 nm line pattern were close to a rectangle was good, and a case where the top shape was round or close to a T-shape or a skirt was seen was judged as x.

Resolution evaluation: 100 nm line and space pattern was exposed at an exposure amount of 1: 1, and the resist pattern was observed with a scanning electron microscope.
A sample having a resolution of 85 nm was marked with ◯. A sample with no resolution, or a symbol with a pattern fall observed, was marked with ×.

Line edge roughness evaluation (LER): The wall surface of the resist pattern after the lithography process is observed with a scanning electron microscope.
If it is 8 nm or less, ◎,
O exceeding 8 nm and 9 nm or less
Δ is greater than 9 nm and less than or equal to 9.5 nm
What exceeded 9.5 nm was set as x.
These results are shown in Table 2.

  According to the salt of the present invention, a pattern having excellent shape, resolution and line edge roughness can be obtained from a resist composition containing the salt.

Claims (9)

A salt represented by the formula (I-BB).

[In the formula (I-BB)
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
X ¹ represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, and the methylene group contained in the saturated hydrocarbon group may be substituted with an oxygen atom or a carbonyl group.
Y ¹ represents 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 36 carbon atoms, the aliphatic hydrocarbon group, The alicyclic hydrocarbon group and the aromatic hydrocarbon group may have a substituent, and the methylene group contained in the aliphatic hydrocarbon group and the alicyclic hydrocarbon group is substituted with an oxygen atom or a carbonyl group. May be.
Do A ¹ and A ² each independently represent an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms? A ¹ and A ² together form a ring having 3 to 20 carbon atoms, and the aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group and ring have a substituent. You may do it.
Ar ¹ represents an (m ₄ +1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a substituent.
m ₁ and m ₂ each independently represent an integer of 0 to 2.
m ₃ represents an integer of 1 to 3. _However, it is _{m 1 + m 2 + m 3} = 3.
m ₄ represents an integer of 1 to 3. ] The salt according to claim 1, wherein Ar ¹ is a phenylene group. The salt according to claim 1 or 2, wherein m ₁ , m ₂ and m ₃ are 1. X ¹ is, salts according to any one of claims 1 to 3 is a group represented by the formula ^(X 1 -1).

[In the formula (X ¹ -1),
X ^a1 represents a single bond or a saturated hydrocarbon group having 1 to 15 carbon atoms, and the methylene group contained in the saturated hydrocarbon group may be substituted with an oxygen atom or a carbonyl group.
* Represents a bond with —C (Q ¹ ) (Q ² ) —. ] Y ¹ is, salts according to any one of claims 1 to 4 is a group represented by any of formulas ^(Y 1 -1) ~ formula ^(Y 1 -3).

[In the formula (Y ¹ -1) to the formula (Y ¹ -3),
The methylene group contained in the ring may be substituted with an oxygen atom or a carbonyl group, and the hydrogen atom contained in the ring may be substituted. ]   The acid generator containing the salt in any one of Claims 1-5. The acid generator according to claim 6 and a resin are contained,
A resist composition, which is a resin having an acid labile group and capable of being dissolved in an alkaline aqueous solution by the action of an acid.   The resist composition according to claim 7, further comprising a basic compound. (1) The process of apply | coating the resist composition of Claim 7 or 8 on a board | substrate,
(2) a step of removing the solvent from the composition after coating to form a composition layer;
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) A method for producing a resist pattern, comprising a step of developing the heated composition layer using a developing device.