JP5677668B2 - Salt, resist composition and method for producing resist pattern - Google Patents

Description

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

A resist composition used for fine processing of a semiconductor using a lithography technique contains an acid generator.
Patent Document 1 describes a salt represented by the following formula as a salt for an acid generator.

JP 2007-161707 A

  A conventional salt for an acid generator may not always satisfy the resolution and line edge roughness (LER) of a pattern obtained from a resist composition containing the salt.

The present invention includes the following inventions [1] to [10].
[1] A salt represented by the formula (I).
[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C ₁ -C ₆ perfluoroalkyl group.
L represents a divalent C _{1 to} C ₁₇ saturated hydrocarbon group, and —CH ₂ — contained in the divalent saturated hydrocarbon group may be replaced by —O— or —CO—.
W ¹ represents a C _{2 to} C ₃₆ heterocycle, and the hydrogen atom contained in the heterocycle is a halogen atom, a hydroxyl group, a C _{1 to} C ₂₄ hydrocarbon group, a C _{1 to} C ₁₂ alkoxy group, C it may be substituted by ₂ -C ₄ acyl group or an acyloxy group of _{C 2} ~C _4, -CH 2 contained in the heterocycle - may be replaced by -O-.
Z ⁺ represents an organic counter ion. ]
[2] The salt according to [1], wherein the salt represented by the formula (I) is a salt represented by the formula (I-1).
[In the formula (I-1),
Q ¹ , Q ² , L and Z ⁺ represent the same meaning as described above.
R ^{34 to} R ³⁹ each independently represent a hydrogen atom or a C _{1 to} C ₂₄ hydrocarbon group, or at least two selected from R ^{34 to} R ³⁹ are bonded to each other to form C _{3 to} C ₃₀ . It forms a ring, hydrogen atom contained in the hydrocarbon group and the ring, a halogen atom, a hydroxyl _group, an alkyl group of C 1 _{-C 12,} alkoxy group of C 1 _{-C 12,} acyl group C 2 -C ₄ Alternatively, it may be substituted with a C _{2 to} C ₄ acyloxy group, and —CH ₂ — contained in the hydrocarbon group and the ring may be replaced with —CO— or —O—.
n represents an integer of 0 to 3. ]
[3] The salt according to [1] or [2], wherein the salt represented by the formula (I) is a salt represented by the formula (I-2).
[In the formula (I-2),
Q ¹ , Q ² , L, Z ⁺ and n represent the same meaning as described above.
R ^{42 to} R ⁵¹ each independently represents a hydrogen atom or a C _{1 to} C ₁₂ hydrocarbon group, or at least two selected from R ^{42 to} R ⁵¹ are bonded to each other to form C _{3 to} C ₂₄ . It forms a ring, hydrogen atom contained in the hydrocarbon group and the ring, a halogen atom, a hydroxyl _group, an alkyl group of C 1 _{-C 12,} alkoxy group of C 1 _{-C 12,} acyl group C 2 -C ₄ Alternatively, it may be substituted with a C _{2 to} C ₄ acyloxy group, and —CH ₂ — contained in the hydrocarbon group and the ring may be replaced with —CO— or —O—.
m represents an integer of 0 to 3. ]
[4] Any one of [1] to [3], wherein the salt represented by the formula (I) is a salt represented by the formula (I-3) or a salt represented by the formula (I-4). Salt.
[In formula (I-3) and formula (I-4), Q ¹ , Q ² , L and Z ⁺ represent the same meaning as described above. ]
[5] L is * —CO— or * —CO—O—CH ₂ —CO— (* represents a bond with —C (Q ¹ ) (Q ² ) —) [1] to The salt according to any one of [4].
[6] The salt according to any one of [1] to [5], wherein Z ⁺ is an arylsulfonium cation.
[7] An acid generator containing the salt according to any one of [1] to [6] as an active ingredient.

[8] The acid generator according to [7] above and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an aqueous alkali solution, and acts on an acid to form an alkali. A resist composition that is a resin that can be dissolved in an aqueous solution.
[9] The resist composition according to [8], which contains a basic compound.

[10] (1) A step of applying the resist composition according to [8] or [9] 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 step of developing the heated composition layer using a developing device;
A method for producing a resist pattern including:

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

In this specification, unless otherwise specified, examples of each substituent are applied to any chemical structural formula having the same substituent while appropriately selecting the number of carbon atoms. Those which can be linear, branched or cyclic include any of them, and they may be mixed. Each substituent can be a monovalent or divalent or higher substituent depending on the binding site. When stereoisomers exist, all 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.

<Salt represented by formula (I)>
The salt of the present invention is represented by the formula (I) (hereinafter sometimes referred to as “salt (I)”).
[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C ₁ -C ₆ perfluoroalkyl group.
L represents a divalent C _{1 to} C ₁₇ saturated hydrocarbon group, and —CH ₂ — contained in the divalent saturated hydrocarbon group may be replaced by —O— or —CO—.
W ¹ represents a C _{2 to} C ₃₆ heterocycle, and the hydrogen atom contained in the heterocycle is a halogen atom, a hydroxyl group, a C _{1 to} C ₂₄ hydrocarbon group, a C _{1 to} C ₁₂ alkoxy group, C it may be substituted by ₂ -C ₄ acyl group or an acyloxy group of _{C 2} ~C _4, -CH 2 contained in the heterocycle - may be replaced by -O-.
Z ⁺ represents an organic counter ion. ]

  Examples of the perfluoroalkyl group include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluoro sec-butyl group, a perfluoro tert-butyl group, a perfluoropentyl group, and a perfluorohexyl group. It is done.

Examples of the divalent saturated hydrocarbon group include linear alkylene, branched alkylene, monocyclic or polycyclic saturated cyclic hydrocarbon group, and the like.
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, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1, Linear alkylene groups such as 17-diyl group, methylidene group, ethylidene group, propylidene group, 2-propylidene group;
A linear alkylene group, the side of the alkyl group (in particular, C ₁ -C ₄ alkyl group, e.g., methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec- butyl group, tert- butyl group, etc.) Having a chain, for example, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2-propylene group, 1-methyl-1,4-butylene A branched alkylene group such as a 2-methyl-1,4-butylene group;
Monocyclic saturated cyclic hydrocarbon groups which are cycloalkylene groups such as 1,3-cyclobutylene group, 1,3-cyclopentylene group, 1,4-cyclohexylene group, 1,5-cyclooctylene group;
Examples thereof include polycyclic saturated cyclic hydrocarbon groups such as 1,4-norbornylene group, 2,5-norbornylene group, 1,5-adamantylene group, 2,6-adamantylene group and the like.
Moreover, what combined 2 or more types of these groups may be used. Further, a divalent group may be formed by using any one hydrogen atom in a monovalent saturated cyclic hydrocarbon described later as a bond.

Examples of the group in which —CH ₂ — contained in the divalent saturated hydrocarbon group is replaced by —O— or —CO— include groups represented by formulas (L1) to (L3). Formula (L1) ~ formula (L3), in the left ^{C (Q 1) (Q 2} ) - bound to, binds to the ring ^{W 1} on the right. The same applies to specific examples of the following formulas (L1) to (L3).

In Formula (L1) to Formula (L3), L ¹ represents a C _{1 to} C ₁₅ saturated hydrocarbon group.
L ² and L ³ each independently represent a C _{1 to} C ₁₂ saturated hydrocarbon group.

Examples of the divalent group represented by the formula (L1) include the following.

Examples of the divalent group represented by the formula (L2) include the following.
Of these, a group represented by formula (L1) or formula (L3) is preferred, and a group represented by formula (L3) is more preferred.

The heterocyclic ring may be monocyclic or polycyclic. Moreover, an aromatic heterocyclic ring may be sufficient and it may not have aromaticity, for example, the following groups are mentioned. * Represents a bond with L.

In addition, examples of the group in which —CH ₂ — contained in the heterocyclic ring is replaced by —O— include the following.

Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
As a hydrocarbon group, any of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group may be sufficient, and the combination of these groups may be sufficient.
For example, as the aliphatic hydrocarbon group, for example, methyl group, ethyl group, 1-methylethyl group (isopropyl group), 1,1-dimethylethyl group (tert-butyl group), 2,2-dimethylethyl group, Propyl group, 1-methylpropyl group, 2,2-dimethylpropyl group, 1-ethylpropyl group, butyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-propylbutyl group, pentyl group, 1-methylpentyl group, hexyl group, 1,4-dimethylhexyl group, heptyl group, 1-methylheptyl group, octyl group, methyloctyl group, methylnonyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, Examples thereof include alkyl groups such as dodecyl group.
The alicyclic hydrocarbon group includes cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, norbornyl group, 1-adamantyl group, 2-adamantyl group, isobornyl And a cycloalkyl group such as a group.
As aromatic hydrocarbon group, phenyl group, naphthyl group, anthranyl group, p-methylphenyl group, p-tert-butylphenyl group, p-adamantylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, biphenyl Groups, anthryl groups, phenanthryl groups, 2,6-diethylphenyl groups, aryl groups such as 2-methyl-6-ethylphenyl, and the like.

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 acyl group include an acetyl group, a propionyl group, and a butyryl group.
Examples of the acyloxy group include an acetyloxy group, a propionyloxy group, a butyryloxy group, and an isobutyryloxy group.

In the salt represented by the formula (I), Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.
Ring W ¹ is a 4-6 membered heterocyclic ring containing a nitrogen atom or a heterocyclic ring containing such a 4-6 membered ring (eg, preferably 4-20 membered, more preferably 4-16 membered polycycle). Or a polycyclic bridged ring). -CO- is preferably arranged at a position adjacent to the nitrogen atom.
The hydrocarbon group in the ring ^{W 1} _{substituents,} C 1 _{-C 12} alkyl group are preferable.

Examples of the salt represented by the formula (I) include a salt represented by the formula (I-1).
[In the formula (I-1),
Q ¹ , Q ² , L and Z ⁺ represent the same meaning as described above.
R ^{34 to} R ³⁹ each independently represent a hydrogen atom or a C _{1 to} C ₂₄ hydrocarbon group, or at least two selected from R ^{34 to} R ³⁹ are bonded to each other to form C _{3 to} C ₃₀ . It forms a ring, hydrogen atom contained in the hydrocarbon group and the ring, a halogen atom, a hydroxyl _group, an alkyl group of C 1 _{-C 12,} alkoxy group of C 1 _{-C 12,} acyl group C 2 -C ₄ Alternatively, it may be substituted with a C _{2 to} C ₄ acyloxy group, and —CH ₂ — contained in the hydrocarbon group and the ring may be replaced with —CO— or —O—.
n represents an integer of 0 to 3. ]

Examples of the salt represented by the formula (I) include the salt represented by the formula (I-2).
[In the formula (I-2),
Q ¹ , Q ² , L, Z ⁺ and n represent the same meaning as described above.
R ^{42 to} R ⁵¹ each independently represents a hydrogen atom or a C _{1 to} C ₁₂ hydrocarbon group, or at least two selected from R ^{42 to} R ⁵¹ are bonded to each other to form C _{3 to} C ₂₄ . It forms a ring, hydrogen atom contained in the hydrocarbon group and the ring, a halogen atom, a hydroxyl _group, an alkyl group of C 1 _{-C 12,} alkoxy group of C 1 _{-C 12,} acyl group C 2 -C ₄ Alternatively, it may be substituted with a C _{2 to} C ₄ acyloxy group, and —CH ₂ — contained in the hydrocarbon group and the ring may be replaced with —CO— or —O—.
m represents an integer of 0 to 3. ]

In formula (I-1) and formula (I-2), the ring formed by combining two of R ^{34 to} R ³⁹ or R ^{42 to} R ⁵¹ is an alicyclic hydrocarbon or the above-described heterocyclic ring. Preferably, it is an alicyclic hydrocarbon.

In the formula (I-1), n is preferably 0 or 1, more preferably 0.
In the formula (I-2), n is preferably 0 or 1, more preferably 0. Further, m is preferably 1 or 2, and more preferably 1.

Specifically, a salt represented by the formula (I-3) or a salt represented by the formula (I-4) is preferable.
[In formula (I-3) and formula (I-4), Q ¹ , Q ² , L and Z ⁺ represent the same meaning as described above. ]

Examples of the salt represented by the formula (I) include the following salts.

Examples of Z ⁺ include onium cations such as sulfonium cations, iodonium cations, ammonium cations, benzothiazolium cations, and phosphonium cations. Among these, a sulfonium cation and an iodonium cation are preferable, and an arylsulfonium cation is more preferable.

Z ⁺ is preferably represented by any one of formulas (Z1) to (Z4).

In these formulas, P ^{a to} P ^c each independently represents a C _{1 to} C ₃₀ aliphatic hydrocarbon group, a C _{3 to} C ₃₆ saturated cyclic hydrocarbon group, or a C _{6 to} C ₁₈ aromatic hydrocarbon group. the aliphatic hydrocarbon group, hydroxy group, may be substituted by C ₁ -C ₁₂ alkoxy or C ₆ -C ₁₈ aromatic hydrocarbon group, the saturated cyclic hydrocarbon group, a halogen atom, C ₂ -C ₄ may be substituted with an acyl group or glycidyl group, the aromatic hydrocarbon group, a halogen atom, hydroxy group, C ₁ -C ₃₆ aliphatic hydrocarbon group, C ₃ -C ₃₆ saturated cyclic it may be substituted with a hydrocarbon group or a C ₁ -C ₁₂ alkoxy group.
P ⁴ and P ⁵ each independently represent a hydroxy group, a C _{1 to} C ₁₂ aliphatic hydrocarbon group or a C _{1 to} C ₁₂ alkoxy group.
P ⁶ and P ⁷ each independently represent a C _{1 to} C ₃₆ aliphatic hydrocarbon group or a C _{3 to} C ₃₆ saturated cyclic hydrocarbon group.
P ⁸ represents a hydrogen atom, C ₁ -C ₃₆ aliphatic hydrocarbon group, C ₃ -C ₃₆ saturated cyclic hydrocarbon group or a C ₆ -C ₁₈ aromatic hydrocarbon group.
The aliphatic hydrocarbon group of P ^{6 to} P ⁸ is preferably C _{1 to} C ₁₂ , and the saturated cyclic hydrocarbon group is preferably C _{3 to} C ₃₆ , more preferably C _{4 to} C ₁₂ .
P ⁹ represents a C ₁ -C ₁₂ aliphatic hydrocarbon group, C ₃ -C ₁₈ saturated cyclic hydrocarbon group, C ₆ -C ₁₈ aromatic hydrocarbon group, the aromatic hydrocarbon group, C ₁ ~ C ₁₂ aliphatic hydrocarbon group, C ₁ -C ₁₂ alkoxy group, C ₃ -C ₁₈ saturated cyclic hydrocarbon group or alkylcarbonyloxy group may be substituted.
P ⁶ and P ⁷ and P ⁸ and P ⁹ may be independently bonded to each other to form a 3-membered ring to a 12-membered ring (preferably a 3-membered ring to a 7-membered ring). —CH ₂ — may be replaced by —O—, —S—, or —CO—.
P ^{10 to} P ¹⁵ each independently represents a hydroxy group, a C _{1 to} C ₁₂ aliphatic hydrocarbon group, or a C _{1 to} C ₁₂ alkoxy group.
E represents -S- or -O-.
i and j, p, r, x and y each independently represents an integer of 0 to 5;
q represents 0 or 1;
v and w each independently represent an integer of 0 to 4.
When any one of p, r, x, y, v, and w is 2, the plurality of P ^{10 to} P ¹⁵ may be the same as or different from each other.

Examples of the aliphatic hydrocarbon group, aromatic hydrocarbon group and alkoxy group are the same as those described above.
The saturated cyclic hydrocarbon group may be monocyclic or polycyclic as a monovalent saturated cyclic hydrocarbon group. For example, a monocyclic saturated cyclic hydrocarbon group such as a cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, methylcyclohexyl group, dimethylcyclohexyl group, cycloheptyl group, cyclooctyl group); condensed aromatic carbon Polycyclic saturated cyclic hydrocarbon groups such as groups obtained by hydrogenating hydrogen groups (for example, hydronaphthyl groups) and bridged cyclic hydrocarbon groups (for example, adamantyl groups, norbornyl groups, methylnorbornyl groups) Can be mentioned. Further, a group in which a bridged ring (for example, a norbornane ring) and a single ring (for example, a cycloheptane ring or a cyclohexane ring) or a polycycle (for example, a decahydronaphthalene ring) or bridged rings are condensed as shown below. Group; group which these combined, etc. are mentioned. In the following formula, * represents a bond.

  Examples of the alkylcarbonyloxy group include a methylcarbonyloxy group, an ethylcarbonyloxy group, an n-propylcarbonyloxy group, an isopropylcarbonyloxy group, an n-butylcarbonyloxy group, a sec-butylcarbonyloxy group, a tert-butylcarbonyloxy group, Examples thereof include a pentylcarbonyloxy group, a hexylcarbonyloxy group, an octylcarbonyloxy group, and a 2-ethylhexylcarbonyloxy group.

Preferred aliphatic hydrocarbon groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, and 2-ethylhexyl. It is a group.
Preferred saturated cyclic hydrocarbon groups are cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclodecyl group, 2-alkyl-2-adamantyl group, 1- (1-adamantyl) -1-alkyl group, And an isobornyl group.
Preferred aromatic hydrocarbon groups are phenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-cyclohexylphenyl group, 4-methoxyphenyl group, biphenylyl group, naphthyl group. It is.
Examples of the aliphatic hydrocarbon group (aralkyl group) whose substituent is an aromatic hydrocarbon group include a benzyl group.
Examples of the 3-membered to 12-membered ring formed by combining P ⁶ and P ⁷ and P ⁸ and P ⁹ with each other include saturated cyclic hydrocarbon groups, aromatic hydrocarbon groups, and combinations thereof.
Among them, examples of the ring formed by P ⁶ and P ⁷ include a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathian-4-ium ring. Can be mentioned. Examples of the ring formed by P ⁸ and P ⁹ include an oxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, and an oxoadamantane ring.

  Among the cations represented by the formulas (Z1) to (Z4), the formula (Z1) is preferable, the cation represented by the formula (Z5) is more preferable, and the triphenylsulfonium cation (in the formula (Z5), More preferably, z is 0).

In formula (Z5), P ^{1 to} P ³ each independently represent a halogen atom, a hydroxy group, a C _{1 to} C ₃₆ aliphatic hydrocarbon group, a C _{3 to} C ₃₆ saturated cyclic hydrocarbon group, or C _{1 to} C _12. Represents an alkoxy group.
The aliphatic hydrocarbon group may be substituted with a hydroxy group, a C _{1 to} C ₁₂ alkoxy group or a C _{6 to} C ₁₈ aromatic hydrocarbon group, and the saturated cyclic hydrocarbon group is a halogen atom, C ₂ -C ₄ acyl group or glycidyl group may be substituted.
z represents the integer of 0-5 each independently. When any one of z is 2 or more, the plurality of P ^{1 to} P ³ may be the same as or different from each other.
In the formula (Z5),
The aliphatic hydrocarbon group is preferably C _{1 to} C ₁₂ , and the saturated cyclic hydrocarbon group is preferably C _{4 to} C ₃₆ .
P ^{1 to} P ³ preferably each independently represent a halogen atom (more preferably a fluorine atom), a hydroxy group, a C _{1 to} C ₁₂ alkyl group or a C _{1 to} C ₁₂ alkoxy group.
Each z is independently preferably 0 or 1.

Examples of the cation represented by the formula (Z1) or (Z5) include the following.

Specific examples of the cation (Z2) include the following.

Specific examples of the cation (Z3) include the following.

Specific examples of the cation (Z4) include the following.

The salt represented by the formula (I) can be arbitrarily combined with the above-mentioned anions and organic cations. Especially, the salt represented by the following is preferable.

The salt represented by the formula (I) can be produced by a method known in the art.
For example, the salt represented by the formula (Ia) can be produced by the following production method.
In the following formula, W ′ represents a C ₂ -C ₃₅ heterocycle.

The salt represented by the formula (Ia-b) can be synthesized by the method described in JP-A-2008-13551.
The salt represented by the formula (Ia) can be obtained by reacting the compound represented by the formula (Ia-a) with the salt represented by the formula (Ia-b) in the presence of a catalyst.
Examples of the solvent include chloroform. Examples of the catalyst include lithium amide.
Examples of the compound represented by the formula (Ia-a) include 2-pyrrolidinone, 3-pyrrolidinone, racemic β-cyclopentane obtained by the reaction of cyclopentene and chlorosulfonyl isocyanate described in JP-T-2007-514775. And lactam, 1,2-dihydro-3H-indol-3-one, and the like.

Moreover, the salt represented by Formula (Ib) can be manufactured with the following manufacturing methods.
First, the compound represented by the formula (Ia-c) can be obtained by reacting the compound represented by the formula (Ia-a) with formaldehyde in the presence of a catalyst.
Examples of the solvent include tetrahydrofuran. Examples of the base catalyst include potassium carbonate.
Subsequently, the salt represented by the formula (Ib) can be obtained by reacting the compound represented by the formula (Ia-c) with the salt represented by the formula (Ia-b) under a catalyst. .
Examples of the solvent include chloroform. Examples of the catalyst include lithium amide.

<Acid generator>
The acid generator of the present invention contains a salt represented by the formula (I) as an active ingredient. When using the salt represented by Formula (I) as an acid generator, you may use individually or in multiple types simultaneously. The acid generator of the present invention further includes a known salt other than the salt represented by the formula (I), a salt composed of a cation and a known anion contained in the salt represented by the formula (I), and a formula ( A salt composed of an anion contained in the salt represented by I) and a known cation may be included.
Such a salt is suitably used as an acid generator used in a resist composition.

<Resist composition>
The resist composition of the present invention contains an acid generator containing a salt represented by formula (I) as an active ingredient and a resin (hereinafter sometimes referred to as “resin (A)”).
In the resist composition of the present invention, as described above, a known salt other than the salt represented by the formula (I) may be used in combination as the acid generator. The content of the acid generator is preferably in the range of about 0.1 to 30% by weight in the solid content of the resist composition.
The resin (A) contained in the resist composition is a resin having an acid labile group and insoluble or hardly soluble in an alkaline aqueous solution. The resin that has reacted with an acid is a resin that can be dissolved in an alkaline aqueous solution. is there. That is, it is insoluble or hardly soluble in the alkaline aqueous solution before contact with the acid, but becomes soluble in the alkaline aqueous solution after contact with the acid. Therefore, in this resist composition, an acid is generated from the salt represented by the formula (I) by exposure, and the acid acts catalytically on an acid-labile group in the resin, thereby preventing the acid. The stable group is cleaved to make the resin soluble in an alkaline aqueous solution.
Such a resist composition is suitable as a chemically amplified positive resist composition.

<Resin (A)>
The resin (A) can be produced by polymerizing a monomer having an acid labile group. As the monomer having an acid labile group, one type may be used alone, or two or more types may be used in combination.

<Monomer having acid-labile group>
The term “acid-labile group” means a group that cleaves a leaving group upon contact with an acid to form a hydrophilic group (for example, a hydroxy group or a carboxy group). Examples of the acid labile group include an alkoxycarbonyl group represented by the formula (a) in which —O— is bonded to a tertiary carbon atom (excluding a bridgehead carbon atom of a bridged cyclic hydrocarbon group) ( That is, an ester bond having a tertiary alcohol residue). The group represented by the formula (a) may be referred to as “acid-labile group (a)”.

In the formula (a), R ^{1 to} R ³ each independently represents an aliphatic hydrocarbon group or a saturated cyclic hydrocarbon group, or R ¹ and R ² may be bonded to each other to form a ring. . * Represents a bond.
Here, examples of the ring formed by combining R ¹ and R ² with each other include a saturated cyclic hydrocarbon group and an aromatic hydrocarbon group.

In Formula (a), in R ^{1 to} R ³ , the hydrogen atom of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group may be substituted with a hydroxy group or the like. In addition, —CH ₂ — in the aliphatic hydrocarbon group and saturated cyclic hydrocarbon group may be replaced with —O— or —CO—.
R ^{1 to} R ³ are preferably C _{1 to} C ₂₀ groups, and more preferably C _{1 to} C ₁₂ groups.

Examples of the acid labile group (a) include:
1,1-dialkylalkoxycarbonyl group (in the formula (a), R ^{1 to} R ³ are alkyl groups, preferably tert-butoxycarbonyl group),
2-alkyl-2-adamantyloxycarbonyl group (in the formula (a), R ¹ , R ² and a carbon atom form an adamantyl group and R ³ is an alkyl group), and 1- (1-adamantyl) -1-alkylalkoxycarbonyl group (in the formula (a), R ¹ and R ² are alkyl groups and R ³ is an adamantyl group) and the like.

  The monomer having an acid labile group is preferably a monomer having an acid labile group (a) and a carbon-carbon double bond, more preferably an acid labile group (a) ( It is a (meth) acrylic monomer.

Among the (meth) acrylic monomers having an acid labile group (a), those having a C _{5 to} C ₂₀ saturated cyclic hydrocarbon group are preferred. If a resin obtained by polymerizing a monomer having a bulky structure such as a saturated cyclic hydrocarbon group is used, the resolution of the resist can be improved.
Examples of the saturated cyclic hydrocarbon group are the same as those described above.

  Among (meth) acrylic monomers having an acid labile group (a) and a saturated cyclic hydrocarbon group, a monomer having an adamantyl group represented by formula (a-1) or a formula (a-2) Monomers having a cyclohexyl group represented are preferred. These may be used alone or in combination of two or more.

In formula (a-1) and formula (a-2),
M is independently, -O- or _{-O- (CH 2) k -CO-} O- the stands, k is an integer of 1-7. However, —O— and the like enumerated in M are bonded to the —CO— of the formula (a-1) and the formula (a-2) on the left side and to the adamantyl group or the cyclohexyl group on the right side. Means.
R ⁴ each independently represents a hydrogen atom or a methyl group.
R ⁵ each independently represents a C _{1 to} C ₈ aliphatic hydrocarbon group or a C _{3 to} C ₁₀ saturated cyclic hydrocarbon group.
s represents an integer of 0 to 14, and t represents an integer of 0 to 10.

M is preferably —O— or —O— (CH ₂ ) _f —CO—O— (wherein f is an integer of 1 to 4), more preferably —O—.
R ⁴ is preferably a methyl group.
The aliphatic hydrocarbon group for R ⁵ is preferably C ₆ or less. Saturated cyclic hydrocarbon group is preferably C ₈ or less, more preferably C ₆ or less.
s is preferably an integer of 0 to 3, more preferably 0 or 1.
t is preferably an integer of 0 to 3, more preferably 0 or 1.

Examples of the monomer represented by the formula (a-1) include the following.

Among these, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, and 2-isopropyl-2-adamantyl (meth) acrylate are preferable, and those in the form of methacrylate are more preferable. .

Examples of the monomer represented by the formula (a-2) include the following.
Among these, 1-ethyl-1-cyclohexyl (meth) acrylate is preferable, and 1-ethyl-1-cyclohexyl methacrylate is more preferable.

  The content of the structural unit derived from the monomer represented by the formula (a-1) or the formula (a-2) in the resin (A) is usually 10 to 95 mol% in all units of the resin, preferably It is 15-90 mol%, More preferably, it is 20-85 mol%.

  Examples of the monomer having an acid labile group (a) and a carbon-carbon double bond include a monomer having a norbornene ring represented by the formula (a-3). Since the resin having a structural unit derived from the monomer (a-3) having a norbornene ring has a bulky structure, the resolution of the resist can be improved. In addition, since a rigid norbornane ring is introduced into the main chain of the resin, the resistance to dry etching of the resist can be improved.

In formula (a-3), R ⁶ represents a hydrogen atom, a C ₁ -C ₃ aliphatic hydrocarbon group optionally having a substituent (for example, a hydroxy group), a carboxy group, a cyano group, or —COOR ^a R ^a represents ^a C _{1 to} C ₈ aliphatic hydrocarbon group or a C _{3 to} C ₈ saturated cyclic hydrocarbon group.
R ^{7 to} R ⁹ each independently represent a C _{1 to} C ₁₂ aliphatic hydrocarbon group or a C _{3 to} C ₁₂ saturated cyclic hydrocarbon group, or R ⁸ and R ⁹ are bonded to each other to form a ring. It may be.
The hydrogen atom of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group in R ^{6 to} R ⁹ may be substituted with a hydroxy group or the like, and —CH ₂ — of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group. May be replaced by —O— or —CO—.

Examples of the aliphatic hydrocarbon group which may have a substituent for R ⁶ include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group.
Examples of R ^a include a methyl group, an ethyl group, a propyl group, a 2-oxo-oxolan-3-yl group, and a 2-oxo-oxolan-4-yl group.

Examples of R ^{7 to} R ⁹ include a methyl group, an ethyl group, a cyclohexyl group, a methylcyclohexyl group, a hydroxycyclohexyl group, an oxocyclohexyl group, and an adamantyl group.
Examples of R ⁸ , R ⁹ and the ring formed by combining these with each other include saturated cyclic hydrocarbon groups, and cyclohexyl group, adamantyl group and the like are particularly suitable.

  Examples of the monomer (a-3) having a norbornene ring include 5-norbornene-2-carboxylic acid-tert-butyl, 5-norbornene-2-carboxylic acid 1-cyclohexyl-1-methylethyl, and 5-norbornene-2. -1-methylcyclohexyl carboxylate, 2-methyl-2-adamantyl 5-norbornene-2-carboxylate, 2-ethyl-2-adamantyl 5-norbornene-2-carboxylate, 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.

  The content of the structural unit derived from the monomer represented by the formula (a-3) in the resin (A) is usually 10 to 95 mol%, preferably 15 to 90 mol% in all the units of the resin. More preferably, it is 20-85 mol%.

Examples of the monomer having an acid labile group (a) and a carbon-carbon double bond include monomers represented by the formula (a-4).
[In the formula (a-4), R ¹⁰ represents a hydrogen atom, a halogen atom or a C ₁ -C ₆ alkyl group which may have a halogen atom.
R ¹¹ is independently a halogen atom, a hydroxyl group, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkoxy group, a C ₂ -C ₄ acyl group, a C ₂ -C ₄ acyloxy group, an acryloyl group or a methacryloyl group. Represents.
h represents an integer of 0 to 4. When h is an integer of 2 or more, the plurality of R ¹¹ may be the same type of group or different types of groups.
R ¹² and R ¹³ each independently represents a hydrogen atom or a C _{1 to} C ₁₂ hydrocarbon group.
X ⁴ represents a C _{1 to} C ₁₇ saturated hydrocarbon group which may have a single bond or a substituent, and —CH ₂ — contained in the saturated hydrocarbon group is —CO—, —O—, -S -, - SO ₂ - or -N ^{(R c)} - may be replaced by. R ^c represents a hydrogen atom or a C _{1 to} C ₆ aliphatic hydrocarbon group.
Y ⁴ is a C _{1 to} C ₁₂ aliphatic hydrocarbon group, a C _{3 to} C ₁₈ saturated cyclic hydrocarbon group or a C _{6 to} C ₁₈ aromatic hydrocarbon group, and the aliphatic hydrocarbon group and saturated cyclic hydrocarbon The group and the aromatic hydrocarbon group may have a substituent. ]

Examples of the alkyl group that may have a halogen atom include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, and a perfluoropentyl group. Perfluorohexyl group, perchloromethyl group, perbromomethyl group, periodomethyl group and the like.
Examples of the substituent such as an alkyl group and an alkoxy group are the same as those described above.

In the formula ^(a-4), the alkyl group in ^{R 10} and ^{R 11} are preferably C ₁ -C ₄ alkyl group, more preferably a C ₁ -C ₂ alkyl group, a methyl group is particularly preferred.
The alkoxy group for R ¹¹ is preferably a C ₁ -C ₄ alkoxy group, more preferably a C ₁ -C ₂ alkoxy group, and particularly preferably a methoxy group.
Examples of the substituent that may be substituted on the group of X ⁴ and Y ⁴ include a halogen atom, a hydroxy group, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkoxy group, a C ₂ -C ₄ acyl group, ₂ -C ₄ acyloxy group, and the like. Of these, a hydroxy group is preferable.

As a monomer (a-4), the following monomers are mentioned, for example.

  The content of the structural unit derived from the monomer represented by the formula (a-4) in the resin (A) is usually 10 to 95 mol%, preferably 15 to 90 mol% in all units of the resin. More preferably, it is 20-85 mol%.

Examples of other acid labile monomers having an acid labile group (a) include the following monomers.

  Content of the structural unit derived from the other acid labile monomer in the resin (A) is usually 10 to 95 mol%, preferably 15 to 90 mol%, more preferably 20 in all units of the resin. -85 mol%.

The resin (A) is preferably a co-polymerization of a monomer (a1) having an acid labile group and a monomer having no acid labile group (hereinafter sometimes referred to as “acid stable monomer”). It is a coalescence. An acid stable monomer may be used individually by 1 type, and may use 2 or more types together.
When the resin (A) is a copolymer of a monomer (a1) having an acid labile group and an acid stable monomer, the structural units derived from the monomer (a1) having an acid labile group are all Preferably it is 10-80 mol% with respect to 100 mol% of structural units, More preferably, it is 20-60 mol%. Further, the structural unit derived from the monomer having an adamantyl group (particularly the monomer (a1-1) having an acid labile group) is added in an amount of 15 mol with respect to 100 mol% of the monomer (a1) having an acid labile group. % Or more is preferable. When the ratio of the monomer having an adamantyl group is increased, the dry etching resistance of the resist is improved.

<Acid stable monomer>
As the acid stable monomer, those having a hydroxy group (b) or a lactone ring (c) are preferable. If a resin having a structural unit derived from an acid-stable monomer having a hydroxy group or an acid-stable monomer containing a lactone ring is used, the resolution of the resist and the adhesion to the substrate can be improved.

<Acid-stable monomer having a hydroxy group (b)>
When the resist composition is used for KrF excimer laser exposure (248 nm), high energy beam exposure such as electron beam or EUV light, an acid stable monomer having a phenolic hydroxyl group (hydroxystyrenes) as an acid stable monomer having a hydroxy group ( It is preferable to use b-1). When using short-wavelength ArF excimer laser exposure (193 nm) or the like, it is preferable to use an acid-stable monomer having a hydroxyadamantyl group represented by the formula (b-2) as the acid-stable monomer having a hydroxy group. The acid stable monomer having a hydroxy group may be used alone or in combination of two or more.

Examples of the monomer having a phenolic hydroxyl group include styrene monomers such as p- or m-hydroxystyrene represented by the formula (b-1).
[In the formula (b-1),
R ¹⁴ represents a hydrogen atom, a halogen atom or a C ₁ -C ₆ alkyl group which may have a halogen atom.
R ¹⁵ represents a halogen atom, a hydroxyl group, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkoxy group, a C ₂ -C ₄ acyl group, a C ₂ -C ₄ acyloxy group, an acryloyl group or a methacryloyl group.
b represents an integer of 0 to 4. When b is an integer of 2 or more, the plurality of R ¹⁵ may be the same type of group or different types of groups. ]

The alkyl group in R ^14, preferably C ₁ -C ₄ alkyl group, C ₁ -C more preferably ₂ alkyl group, a methyl group is particularly preferred.
Further, the alkoxy group is preferably a C ₁ -C ₄ alkoxy group, more preferably C ₁ -C ₂ alkoxy group, a methoxy group is particularly preferred.

  When obtaining a copolymer resin having a structural unit derived from the monomer (b-1) having such a phenolic hydroxyl group, after radical polymerization of the corresponding (meth) acrylic acid ester monomer, acetoxystyrene and styrene, an acid is obtained. Can be obtained by deacetylation.

Examples of the monomer represented by the formula (b-1) include the following.

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

  The content of the structural unit derived from the monomer represented by the formula (b-1) in the resin (A) is usually from 5 to 90 mol%, preferably from 10 to 85 mol%, in all units of the resin. More preferably, it is 15-80 mol%.

  Examples of the acid stable monomer having a hydroxyadamantyl group include a monomer represented by the formula (b-2).

In formula (b-2), M ² represents —O— or —O— (CH ₂ ) _k —CO—O—, and k represents an integer of 1 to 7.
R ¹⁶ represents a hydrogen atom or a methyl group.
R ¹⁷ and R ¹⁸ each independently represents a hydrogen atom, a methyl group or a hydroxy group.
c represents an integer of 0 to 10.

M ² is preferably —O—, —O— (CH ₂ ) _f —CO—O— (wherein f is an integer of 1 to 4), and more preferably —O—.
R ¹⁶ is preferably a methyl group.
R ¹⁷ is preferably a hydrogen atom.
R ¹⁸ is preferably a hydrogen atom or a hydroxy group.
c is preferably an integer of 0 to 3, more preferably 0 or 1.

Examples of the monomer represented by the formula (b-2) include the following.

Among these, 3-hydroxy-1-adamantyl (meth) acrylate, 3,5-dihydroxy-1-adamantyl (meth) acrylate and 1- (3,5-dihydroxy-1-adamantyloxycarbonyl) methyl (meth) acrylate 3-hydroxy-1-adamantyl (meth) acrylate and 3,5-dihydroxy-1-adamantyl (meth) acrylate are more preferred, 3-hydroxy-1-adamantyl methacrylate and 3,5-dihydroxy-1-adamantyl More preferred is methacrylate.

  The content of the structural unit derived from the monomer represented by the formula (b-2) in the resin (A) is usually 3 to 40 mol%, preferably 5 to 35 mol%, in all units of the resin. More preferably, it is 5-30 mol%.

<Acid-stable monomer having a lactone ring (c)>
The lactone ring (c) possessed by the acid-stable monomer may be a single ring such as a β-propiolactone ring, γ-butyrolactone ring, or δ-valerolactone ring, and may be a monocyclic lactone ring and other rings. The condensed ring may be used. Among these lactone rings, a γ-butyrolactone ring and a condensed ring of a γ-butyrolactone ring and another ring are preferable.

  The acid-stable monomer having a lactone ring is represented by, for example, the formula (c-1), the formula (c-2), or the formula (c-3). These 1 type may be used independently and may use 2 or more types together.

In formula (c-1) to formula (c-3),
M ² each independently, -O- or _{-O- (CH 2) k -CO-} O- the stands, k is an integer of 1-7.
R ¹⁹ each independently represents a hydrogen atom or a methyl group.
R ²⁰ represents a C ₁ -C ₄ aliphatic hydrocarbon group,
d represents an integer of 0 to 5.
R ²¹ and R ²² each independently represent a carboxy group, a cyano group, or a C ₁ -C ₄ aliphatic hydrocarbon group, and e and g each independently represent an integer of 0 to 3.
When d, e, or g is 2 or more, the plurality of R ²⁰ , R ^21, or R ²² may be the same as or different from each other.

M ² is each independently preferably —O—, —O— (CH ₂ ) _f —CO—O— (wherein f is an integer of 1 to 4), more preferably —O—. It is. However, —O— and the like listed for M ² mean that they are bonded to —CO— in the formula (c-1) to the formula (c-3) on the left side and to the lactone ring on the right side.
R ¹⁹ is preferably a methyl group.
R ²⁰ is preferably a methyl group.
R ²¹ and R ²² are preferably each independently a carboxy group, a cyano group or a methyl group.
d, e and g are each independently preferably 0 to 2, more preferably 0 or 1.

Examples of the monomer represented by the formula (c-1) include the following.

Examples of the monomer represented by the formula (c-2) include the following.

Examples of the monomer represented by the formula (c-3) include the following.

Among acid stable monomers having a lactone ring (c), (meth) acrylic acid (5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonan-2-yl, (meth) acrylic Acid tetrahydro-2-oxo-3-furyl, 2- (5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonan-2-yloxy) -2-oxoethyl (meth) acrylate Are preferred, and those in the form of methacrylate are more preferred.

The content of the structural unit derived from the monomer represented by the formula (c-1), the formula (c-2) or the formula (c-3) in the resin (A) is usually 5 to 50 in all units of the resin. It is mol%, Preferably it is 10-45 mol%, More preferably, it is 15-40 mol%.

<Other acid stable monomers>
Other acid stable monomers include, for example, maleic anhydride represented by formula (d-1), itaconic anhydride represented by formula (d-2), or norbornene ring represented by formula (d-3) And acid-stable monomers having
In formula (d-3), R ²³ and R ²⁴ are each independently a hydrogen atom, a C ₁ -C ₃ aliphatic hydrocarbon group optionally having a substituent (for example, a hydroxy group), or a cyano group. , A carboxy group or —COOR ²⁵ , or R ²³ and R ²⁴ are bonded to each other to form —CO—O—CO—, and R ²⁵ is a C _{1 to} C ₃₆ aliphatic hydrocarbon group or C ₃ to C ₃₆ represents a saturated cyclic hydrocarbon group, and —CH ₂ — in the aliphatic hydrocarbon group and saturated cyclic hydrocarbon group may be replaced by —O— or —CO—. However, those in which —COOR ²⁵ is an acid labile group are excluded (that is, R ²⁵ does not include those in which a tertiary carbon atom is bonded to —O—).

Examples of the aliphatic hydrocarbon group which may have a substituent for R ²³ and R ²⁴ include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group.
The aliphatic hydrocarbon group for R ²⁵ is preferably C _{1 to} C ₈ , more preferably C _{1 to} C ₆ , and the saturated cyclic hydrocarbon group is preferably C _{4 to} C ₃₆ , more preferably C ₄ to C ₆ . it is a C _12. Examples of R ²⁵ include a methyl group, an ethyl group, a propyl group, a 2-oxo-oxolan-3-yl group, and a 2-oxo-oxolan-4-yl group.

  Examples of the acid-stable monomer (d-3) having a norbornene ring include 2-norbornene, 2-hydroxy-5-norbornene, 5-norbornene-2-carboxylic acid, methyl 5-norbornene-2-carboxylate, 5- Examples include norbornene-2-carboxylic acid 2-hydroxy-1-ethyl, 5-norbornene-2-methanol, and 5-norbornene-2,3-dicarboxylic acid anhydride.

  Content of the structural unit derived from the monomer represented by Formula (d-1), Formula (d-2), or Formula (d-3) in the resin is usually 2 to 40 mol% in all units of the resin. Yes, preferably 3-30 mol%, more preferably 5-20 mol%.

A preferred resin (A) is a copolymer obtained by polymerizing at least a monomer (a) having an acid labile group, an acid stable monomer (b) having a hydroxy group and / or an acid stable monomer (c) having a lactone ring. It is a polymer. In this preferred copolymer, the monomer (a) having an acid labile group is more preferably at least one of a monomer (a-1) having an adamantyl group and a monomer (a-2) having a cyclohexyl group. A species (more preferably a monomer (a-1) having an adamantyl group), and an acid-stable monomer (b) having a hydroxy group, preferably an acid-stable monomer (b-2) having a hydroxyadamantyl group, and a lactone The acid-stable monomer (c) having a ring is more preferably an acid-stable monomer (c-1) having a γ-butyrolactone ring and an acid-stable monomer (c-2) having a condensed ring of a γ-butyrolactone ring and a norbornane ring At least one of the following.
Resin (A) can be manufactured by a well-known polymerization method (for example, radical polymerization method).

  The weight average molecular weight of the resin (A) is preferably 2,500 or more (more preferably 3,000 or more) and 50,000 or less (more preferably 30,000 or less). In addition, as described in the Examples, the weight average molecular weight is a value obtained by gel permeation chromatography using polystyrene as a standard product.

  It is preferable that content of resin (A) is 80 mass% or more in solid content of a composition. In the present specification, the “solid content in the composition” means the total of the composition components excluding the solvent. The solid content in the composition and the content of the resin (A) relative thereto can be measured by known analytical means such as liquid chromatography or gas chromatography.

<Basic compound (hereinafter sometimes referred to as “basic compound (C)”)>
The resist composition of the present invention may further contain a basic compound (C). The content of the basic compound (C) is preferably about 0.01 to 1% by mass based on the solid content of the resist composition.

  The basic compound (C) is preferably a basic nitrogen-containing organic compound (for example, an amine). The amine may be an aliphatic amine or an aromatic amine. As the aliphatic amine, any of primary amine, secondary amine and tertiary amine can be used. The aromatic amine may be any of an amino group bonded to an aromatic ring such as aniline and a heteroaromatic amine such as pyridine. Preferable basic compound (C) includes an aromatic amine represented by the formula (C2), particularly an aniline represented by the formula (C2-1).

In formula (C2) and formula (C2-1),
Ar represents an aromatic hydrocarbon group.
T ¹ and T ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group, a saturated cyclic hydrocarbon group, or an aromatic hydrocarbon group,
T ³ represents an aliphatic hydrocarbon group, an alkoxy group, a saturated cyclic hydrocarbon group, an aromatic hydrocarbon group,
Even if the hydrogen atom of the aliphatic hydrocarbon group, saturated cyclic hydrocarbon group, aromatic hydrocarbon group or alkoxy group in T ^{1 to} T ³ is substituted with a hydroxy group, an amino group or a C _{1 to} C ₆ alkoxy group well, wherein the amino group may be substituted by C ₁ -C ₄ alkyl group.
o represents an integer of 0 to 3, and when o is 2 or more, the plurality of T ³ may be the same as or different from each other.

The aliphatic hydrocarbon group is preferably an alkyl group or a cycloalkyl group. The aliphatic hydrocarbon group is preferably about C _{1 to} C ₆ , the saturated cyclic hydrocarbon group is preferably about C _{5 to} C ₁₀ , and the aromatic hydrocarbon group is preferably C ₆ to C ₆ . is about C _10, alkoxy group is preferably about _C 1 -C _6.

Examples of the aromatic amine (C2) include 1-naphthylamine and 2-naphthylamine.
Examples of aniline (C2-1) include aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, N-methylaniline, N, N-dimethylaniline, diphenylamine and the like. Among these, diisopropylaniline (particularly 2,6-diisopropylaniline) is preferable.

Moreover, as a basic compound (C), the compound represented by Formula (C3)-Formula (C11) is mentioned.
In formula (C3) to formula (C11),
T ¹ , T ² , T ³ and o have the same meaning as above.
T ⁴ represents an aliphatic hydrocarbon group, a saturated cyclic hydrocarbon group, or an alkanoyl group.
u represents an integer of 0 to 8. When o or u is an integer of 2 or more, the plurality of T ³ or T ⁴ may be the same as or different from each other.
Each A is independently a divalent aliphatic hydrocarbon group, —CO—, —C (═NH) —, —C (═NR ^{36 ′} ) —, —S—, —S—S—, or Represents a combination. R ^{36 ′} represents a C ₁ -C ₄ alkyl group.

Here, the aliphatic hydrocarbon group is preferably about C _{1 to} C ₆ , the saturated cyclic hydrocarbon group is preferably about C _{3 to} C ₆ , and the alkanoyl group is preferably C _{2 to} C _6. Degree.
The divalent aliphatic hydrocarbon group is preferably an alkylene group, and more preferably about C _{1 to} C ₆ .
Here, examples of the alkanoyl group include an acetyl group, an ethylcarbonyl group, and a heptylcarbonyl group.

  Examples of the compound (C3) include hexylamine, heptylamine, octylamine, nonylamine, decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine, tripropylamine, Tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctyl Amine, methyl dinonyl amine, methyl didecyl amine, ethyl dibutyl amine, ethyl dipentyl amine, ethyl di Silamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine, tris [2- (2-methoxyethoxy) ethyl] amine, triisopropanolamine ethylenediamine, tetramethylenediamine, hexamethylene Examples include diamine, 4,4′-diamino-1,2-diphenylethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, 4,4′-diamino-3,3′-diethyldiphenylmethane, and the like.

Examples of the compound (C4) include piperazine.
Examples of the compound (C5) include morpholine.
Examples of the compound (C6) include piperidine and hindered amine compounds having a piperidine skeleton described in JP-A No. 11-52575.
Examples of the compound (C7) include 2,2′-methylenebisaniline.
Examples of the compound (C8) include imidazole and 4-methylimidazole.
Examples of the compound (C9) include pyridine and 4-methylpyridine.
Examples of the compound (C10) include 1,2-di (2-pyridyl) ethane, 1,2-di (4-pyridyl) ethane, 1,2-di (2-pyridyl) ethene, and 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 and the like can be mentioned.
Examples of the compound (C11) include bipyridine.

<Solvent (hereinafter sometimes referred to as “solvent (E)”)>
The resist composition of the present invention may contain a solvent (E). The resist composition of the present invention containing the solvent (E) is suitable for producing a thin film resist.
The content of the solvent (E) is 90% by mass or more (preferably 92% by mass or more, more preferably 94% by mass or more) and 99.9% by mass or less (preferably 99% by mass or less) in the composition. The content of the solvent (E) can be measured by a known analysis 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 And esters such as ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; cyclic esters such as γ-butyrolactone; A solvent (E) may be used individually by 1 type, and may use 2 or more types together.

<Other components (hereinafter sometimes referred to as “other components (F)”)>
The resist composition of this invention may contain the other component (F) as needed. Component (F) is not particularly limited, and additives known in the resist field, such as sensitizers, dissolution inhibitors, surfactants, stabilizers, dyes, and the like can be used.

<Method for producing resist pattern>
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. At this time, an immersion exposure machine may be used. Usually, exposure is 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.

<Application>
The composition of the present invention is useful for a resist composition, particularly a chemically amplified photoresist composition, such as semiconductor microfabrication, production of circuit boards such as liquid crystals and thermal heads, and other photofabrication processes. It can be suitably used for a wide range of applications. In particular, it can be used as a chemically amplified photoresist composition suitable for excimer laser lithography such as ArF and KrF, ArF immersion exposure lithography, EB exposure lithography, and EUV exposure lithography. In addition to immersion exposure, it can also be used for dry exposure. Furthermore, it can be used for double imaging and is industrially useful.

Hereinafter, the present invention will be described in detail by way of examples.
In Examples and Comparative Examples, “%” and “part” representing content and use amount are based on mass unless otherwise specified.
The weight average molecular weight is a value obtained by gel permeation chromatography (HLC-8120GPC, manufactured by Tosoh Corporation, three columns are “TSKgel Multipore HXL-M”, and the solvent is tetrahydrofuran) using polystyrene as a standard product.
Column: TSKgel Multipore H _XL -M x 3 + 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)

Example 1: Synthesis of a salt represented by the formula (B1)
First, a salt represented by the formula (B1-b) was synthesized by the method described in JP-A-2008-13551.
Subsequently, 4.52 parts of a compound represented by the formula (B1-b), 30.00 parts of chloroform, a compound represented by the formula (B1-a) (trade name: 6-azabicyclo [3.2.0] heptane -7-one manufactured by Kanto Chemical Co., Ltd.) 1.33 parts, molecular sieve (trade name: molecular sieve 5A, manufactured by Wako Pure Chemical Industries, Ltd.) 5.00 parts and lithium amide 0.14 parts were charged and heated to reflux at 80 ° C. for 6 hours. Filtered. The obtained filtrate was charged with 10 parts of ion-exchanged water, stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 parts of activated carbon, stirred at 23 ° C. for 30 minutes, and filtered. The filtrate was concentrated and 5.00 parts of acetonitrile was added and dissolved in the resulting concentrate. This was concentrated, 5 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 0.12 part of a salt represented by the formula (B1) as an oily substance.

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 268.0

Example 2: Synthesis of a salt represented by the formula (B2)
1.67 parts of the compound represented by the formula (B1-a) and 25 parts of tetrahydrofuran were charged and stirred at 23 ° C. for 30 minutes. Thereafter, 1.43 parts of pyridine was charged and the temperature was raised to 40 ° C. Further, a mixed solution of 2.55 parts of chloroacetyl chloride and 5 parts of tetrahydrofuran was added dropwise over 1 hour. Thereafter, the mixture was stirred at 40 ° C. for 3 hours, and the temperature was lowered to 5 ° C. 10 parts of ion-exchanged water cooled to 5 ° C. and 40 parts of ethyl acetate were added, stirred and separated. The recovered organic layer was washed by adding 10 parts of a 10% aqueous potassium carbonate solution at 5 ° C. and separated to recover the organic layer. Further, 10 parts of ion-exchanged water was added to the recovered organic layer and washed with water, followed by liquid separation to recover the organic layer. This washing operation was repeated 5 times. The recovered organic layer was concentrated and fractionated in a column under the following conditions to obtain 1.61 parts of a compound represented by the formula (B2-a).
Developing medium; silica gel 60-200 mesh; made by Merck developing solvent: ethyl acetate

2.50 parts of a salt represented by the formula (B2-b) and 12.50 parts of dimethylformamide were charged and stirred at 23 ° C. for 30 minutes. To the obtained mixture, 0.79 part of potassium carbonate and 0.24 part of potassium iodide were charged and stirred at 40 ° C. for 1 hour. Thereafter, a solution prepared by dissolving 1.07 parts of the compound represented by the formula (B2-a) in 5.00 parts of dimethylformamide was added dropwise over 1 hour. Stir at 40 ° C. for 6 hours and cool to 23 ° C. The obtained reaction product was charged with 100 parts of chloroform, 15 parts of a 5% oxalic acid aqueous solution and 10 parts of ion-exchanged water, and stirred and separated. Into the collected organic layer, 40 parts of ion-exchanged water was charged, stirred and separated. Water washing was performed 5 times. The obtained organic layer was charged with 1.00 parts of activated carbon, stirred at 23 ° C. for 30 minutes, and filtered. The filtrate was concentrated. The resulting concentrate was dissolved by adding 10 parts of acetonitrile, concentrated, added with 10 parts of ethyl acetate 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. The obtained concentrate was separated by column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain 0.58 parts of the salt represented by the formula (B2).

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 326.0

Example 3: Synthesis of a salt represented by the formula (B3)
4.95 parts of a compound represented by the formula (B3-b), 30.00 parts of chloroform, a compound represented by the formula (B1-a) (trade name: 6-azabicyclo [3.2.0] heptane-7 -ON manufactured by Kanto Chemical Co., Ltd.) 1.33 parts, molecular sieve (trade name: Molecular sieve 5A, manufactured by Wako Pure Chemical Industries, Ltd.) 5.00 parts and lithium amide 0.14 parts were charged, heated to reflux at 80 ° C. for 6 hours, and filtered. . The obtained filtrate was charged with 10 parts of ion-exchanged water, stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 parts of activated carbon, stirred at 23 ° C. for 30 minutes, and filtered. The filtrate was concentrated and 5.00 parts of acetonitrile was added and dissolved in the resulting concentrate. This was concentrated, 5 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. The resulting concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain 0.48 parts of the salt represented by the formula (B3).

MS (ESI (+) Spectrum): M ⁺ 305.1
MS (ESI (-) Spectrum): M ^- 268.0

Example 4: Synthesis of salt represented by formula (B4)
4.70 parts of a compound represented by the formula (B4-b), 30.00 parts of chloroform, a compound represented by the formula (B1-a) (trade name: 6-azabicyclo [3.2.0] heptane-7 -ON manufactured by Kanto Chemical Co., Ltd.) 1.33 parts, molecular sieve (trade name: Molecular sieve 5A, manufactured by Wako Pure Chemical Industries, Ltd.) 5.00 parts and lithium amide 0.14 parts were charged, heated to reflux at 80 ° C. for 6 hours, and filtered. . The obtained filtrate was charged with 10 parts of ion-exchanged water, stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 parts of activated carbon, stirred at 23 ° C. for 30 minutes, and filtered. The filtrate was concentrated. To the obtained concentrate, 5.00 parts of acetonitrile was added and dissolved. This was concentrated, 5 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. The obtained concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain 0.16 parts of the salt represented by the formula (B4).

MS (ESI (+) Spectrum): M ⁺ 281.0
MS (ESI (-) Spectrum): M ^- 268.0

Example 5: Synthesis of salt represented by formula (B5)
3.96 parts of a compound represented by the formula (B5-b), 30.00 parts of chloroform, a compound represented by the formula (B1-a) (trade name: 6-azabicyclo [3.2.0] heptane-7 -ON manufactured by Kanto Chemical Co., Ltd.) 1.33 parts, molecular sieve (trade name: Molecular sieve 5A, manufactured by Wako Pure Chemical Industries, Ltd.) 5.00 parts and lithium amide 0.14 parts were charged, heated to reflux at 80 ° C. for 6 hours, and filtered. . The obtained filtrate was charged with 10 parts of ion-exchanged water, stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 parts of activated carbon, stirred at 23 ° C. for 30 minutes, and filtered. The filtrate was concentrated and 5.00 parts of acetonitrile was added and dissolved in the resulting concentrate. This was concentrated, 5 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. The obtained concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain 0.16 parts of the salt represented by the formula (B5).

MS (ESI (+) Spectrum): M ^<+> 207.1
MS (ESI (-) Spectrum): M ^- 268.0

Example 6: Synthesis of salt represented by formula (B6)
4.95 parts of the compound represented by the formula (B3-b), 30.00 parts of chloroform, 2.12 parts of the compound represented by the formula (B6-a), molecular sieve (trade name: Molecular sieve 5A Wako Pure Chemical Industries, Ltd.) 5.00 parts) and lithium amide 0.14 parts were charged, heated to reflux at 80 ° C. for 6 hours, and filtered. The obtained filtrate was charged with 10 parts of ion-exchanged water, stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 parts of activated carbon, stirred at 23 ° C. for 30 minutes, and filtered. The filtrate was concentrated and 5.00 parts of acetonitrile was added and dissolved in the resulting concentrate. This was concentrated, 5 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. The obtained concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain 0.44 parts of the salt represented by the formula (B6).

MS (ESI (+) Spectrum): M ⁺ 305.1
MS (ESI (-) Spectrum): M ^- 334.1

Synthesis Example 1: Synthesis of Resin A1 Monomer E, monomer F, monomer B, monomer C and monomer D were charged in a molar ratio of 30: 14: 6: 20: 30. Subsequently, 1.5 mass times dioxane was added with respect to the total mass of all the 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. And heated at 73 ° C. for about 5 hours. Thereafter, the reaction solution is purified by performing the operation of pouring into a large amount of methanol / water mixed solvent (4: 1) and precipitating three times, and the weight average molecular weight is about 8.1 × 10 ^3. The coalescence was obtained with a yield of 65%. The obtained copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin A1.

Synthesis Example 2: Synthesis of Resin A2 Monomer A, monomer B and monomer C were charged in a molar ratio of 50:25:25, and then 1.5 mass times dioxane was added to the total mass of all monomers. It was. 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. This was heated at 77 ° C. for about 5 hours. Thereafter, the reaction solution is purified by pouring it into a large amount of methanol / water mixed solvent (3: 1) and precipitating three times, and the weight average molecular weight is about 8.0 × 10 ^3. The coalescence was obtained in 60% yield. This copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin A2.

Examples and Comparative Examples The above components and the following components were mixed and dissolved in the compositions shown in Table 1 and further filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist composition.

<Acid generator>
Acid generator B7:
Acid generator B8:
Acid generator B9:

<Basic compound: Quencher>
Quencher C1: 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

(Formation and evaluation of resist pattern)
An organic antireflective coating composition [ARC-29; manufactured by Nissan Chemical Industries, Ltd.] was applied onto a 12-inch silicon wafer and baked at 205 ° C. for 60 seconds to obtain a thickness of 78 nm. An organic antireflection film was formed.
Next, the resist composition was spin-coated on the organic antireflection film so that the film thickness after drying was 85 nm.
The obtained silicon wafer was pre-baked (PB) for 60 seconds on a direct hot plate at the temperature described in the “PB” column of Table 1. Using this silicon wafer, an ArF excimer stepper for immersion exposure [XT: 1900 Gi; manufactured by ASML, NA = 1.35, 3/4 Annular XY-polarized light] is used to change the exposure amount step by step. The space pattern was exposed.
After the exposure, post-exposure baking (PEB) was performed on the hot plate at the temperature described in the “PEB” column of Table 1 for 60 seconds.
Further, paddle development was performed for 60 seconds with an aqueous 2.38 mass% tetramethylammonium hydroxide solution.

  In each resist film, the exposure amount at which the 50 nm line and space pattern becomes an exposure amount of 1: 1 was defined as the effective sensitivity.

  Resolution evaluation: In terms of effective sensitivity, the resist pattern was observed with a scanning electron microscope, and the resolution of 43 nm was evaluated as ◎, the resolution of 45 nm as ◯, and the resolution as low as ×.

Line edge roughness evaluation (LER): The surface of the resist pattern after the lithography process is observed with a scanning electron microscope, and the contact width of the unevenness on the side wall of the resist pattern is 4.5 nm or less. Is over 5 nm.
These results are shown in Table 2.

Thus, according to the resist composition of the present invention, the resolution and line edge roughness of the resulting pattern can be significantly improved.

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

Claims (10)

A salt represented by the formula (I).
[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C ₁ -C ₆ perfluoroalkyl group.
L represents a divalent C _{1 to} C ₁₇ saturated hydrocarbon group, and —CH ₂ — contained in the divalent saturated hydrocarbon group may be replaced by —O— or —CO—.
W ¹ represents a C _{2 to} C ₃₆ heterocycle, and the hydrogen atom contained in the heterocycle is a halogen atom, a hydroxyl group, a C _{1 to} C ₂₄ hydrocarbon group, a C _{1 to} C ₁₂ alkoxy group, C may be substituted by ₂ -C ₄ acyloxy group the acyl group or a _{C 2} ~C _4, -CH 2 contained in the heterocycle - may rather good be replaced by -O-, in ^{W 1} -CO- is arranged adjacent to the nitrogen atom in the same ring .
Z ⁺ represents an organic counter ion. ] The salt according to claim 1, wherein the salt represented by the formula (I) is a salt represented by the formula (I-1).
[In the formula (I-1),
Q ¹ , Q ² , L and Z ⁺ represent the same meaning as described above.
R ^{34 to} R ³⁹ each independently represent a hydrogen atom or a C _{1 to} C ₂₄ hydrocarbon group, or at least two selected from R ^{34 to} R ³⁹ are bonded to each other to form C _{3 to} C ₃₀ . It forms a ring, hydrogen atom contained in the hydrocarbon group and the ring, a halogen atom, a hydroxyl _group, an alkyl group of C 1 _{-C 12,} alkoxy group of C 1 _{-C 12,} acyl group C 2 -C ₄ Alternatively, it may be substituted with a C _{2 to} C ₄ acyloxy group, and —CH ₂ — contained in the hydrocarbon group and the ring may be replaced with —CO— or —O—.
n represents an integer of 0 to 3. ] The salt according to claim 1 or 2, wherein the salt represented by the formula (I) is a salt represented by the formula (I-2).
[In the formula (I-2),
Q ¹ , Q ² , L, Z ⁺ and n represent the same meaning as described above.
R ^{42 to} R ⁵¹ each independently represents a hydrogen atom or a C _{1 to} C ₁₂ hydrocarbon group, or at least two selected from R ^{42 to} R ⁵¹ are bonded to each other to form C _{3 to} C ₂₄ . It forms a ring, hydrogen atom contained in the hydrocarbon group and the ring, a halogen atom, a hydroxyl _group, an alkyl group of C 1 _{-C 12,} alkoxy group of C 1 _{-C 12,} acyl group C 2 -C ₄ Alternatively, it may be substituted with a C _{2 to} C ₄ acyloxy group, and —CH ₂ — contained in the hydrocarbon group and the ring may be replaced with —CO— or —O—.
m represents an integer of 0 to 3. ] The salt according to any one of claims 1 to 3, wherein the salt represented by the formula (I) is a salt represented by the formula (I-3) or a salt represented by the formula (I-4).
[In formula (I-3) and formula (I-4), Q ¹ , Q ² , L and Z ⁺ represent the same meaning as described above. ] L is, * - CO- or _{* -CO-O-CH 2 -CO} - (* ^{is, -C (Q 1) (Q} 2) - bond to a representative) of any of claims 1 to 4 Or a salt thereof. The salt according to any one of claims 1 to 5, wherein Z ⁺ is an arylsulfonium cation.   The acid generator which contains the salt in any one of Claims 1-6 as an active ingredient.   The acid generator according to claim 7 and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, and can be dissolved in an alkaline aqueous solution by acting with an acid. Resist composition which is resin.   The resist composition according to claim 8 containing a basic compound. (1) The process of apply | coating the resist composition of Claim 8 or 9 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.