JP5703662B2 - Salt and resist composition for acid generator - Google Patents

Description

  The present invention relates to a salt for an acid generator and a resist composition.

A resist composition used for fine processing of a semiconductor using a lithography technique contains an acid generator.
Patent Document 1 describes a resist composition containing p-tolyldiphenylsulfonium perfluorooctane sulfonate as a salt for an acid generator.
Patent Document 2 describes a salt represented by the following as a salt for an acid generator.

JP 2003-280200 A JP 2002-214774 A

  In the case of a conventional salt, the line edge roughness of a pattern obtained from a resist composition containing the salt may not always be satisfied.

［式（Ｉ）中、Ｑ^１及びＱ^２は、それぞれ独立に、フッ素原子又はＣ_1-6ペルフルオロアルキル基を表す。
ｎは１〜３の整数を表す。
Ｚ⁺は、式（ｂ２−１）で表されるカチオン、式（ｂ２−２）で表されるカチオン又は式（ｂ２−３）で表されるカチオンを表す。］

［式（ｂ２−１）中、Ｒ^b4〜Ｒ^b6は、それぞれ独立に、Ｃ_1-30脂肪族炭化水素基、Ｃ_3-36飽和環状炭化水素基又はＣ_6-18芳香族炭化水素基を表し、該芳香族炭化水素基に含まれる水素原子は、ハロゲン原子、ヒドロキシ基、Ｃ_1-36脂肪族炭化水素基、Ｃ_3-36飽和環状炭化水素基又はＣ_1-12アルコキシ基で置換されていてもよい。但し、Ｒ^b4〜Ｒ^b6の少なくとも１つは、Ｃ_6-18芳香族炭化水素基を表す。］

［式（ｂ２−２）中、Ｒ^b7及びＲ^b8は、それぞれ独立に、ヒドロキシ基、Ｃ_1-12脂肪族炭化水素基又はＣ_1-12アルコキシ基を表す。
ｍ２及びｎ２は、それぞれ独立に０〜５の整数を表す。ｍ２が２以上である場合、複数のＲ^b7は同じであっても異なっていてもよく、ｎ２が２以上である場合、複数のＲ^b8は同じであっても異なっていてもよい。］

［式（ｂ２−３）中、Ｒ^b9及びＲ^b10は、それぞれ独立に、Ｃ_1-36脂肪族炭化水素基又はＣ_3-36飽和環状炭化水素基を表すか、Ｓとともに環を形成し、該環に含まれる−ＣＨ_２−は、−Ｏ−又は−Ｓ−で置き換わっていてもよい。
Ｒ^b11は、水素原子、Ｃ_1-36脂肪族炭化水素基又はＣ_3-36飽和環状炭化水素基を表す。
Ｒ^b12は、Ｃ_6-18芳香族炭化水素基を表し、該芳香族炭化水素基に含まれる水素原子は、Ｃ_1-12脂肪族炭化水素基、Ｃ_1-12アルコキシ基、ニトロ基、Ｃ_3-18飽和環状炭化水素基又はアルキルカルボニルオキシ基で置換されていてもよい。］ The present invention includes the following inventions.
[1] A salt represented by the formula (I).

[In Formula (I), Q ¹ and Q ² each independently represents a fluorine atom or a C _1-6 perfluoroalkyl group.
n represents an integer of 1 to 3.
Z ⁺ represents a cation represented by the formula (b2-1), a cation represented by the formula (b2-2), or a cation represented by the formula (b2-3). ]

[In formula (b2-1), R ^{b4 to} R ^b6 each independently represents a C _1-30 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group. A hydrogen atom contained in the aromatic hydrocarbon group is substituted with a halogen atom, a hydroxy group, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _1-12 alkoxy group It may be. However, at least one of R ^{b4 to} R ^b6 represents a C _6-18 aromatic hydrocarbon group. ]

[In Formula (b2-2), R ^b7 and R ^b8 each independently represent a hydroxy group, a C _1-12 aliphatic hydrocarbon group, or a C _1-12 alkoxy group.
m2 and n2 each independently represent an integer of 0 to 5. When m2 is 2 or more, the plurality of R ^b7 may be the same or different, and when n2 is 2 or more, the plurality of R ^b8 may be the same or different. ]

[In Formula (b2-3), R ^b9 and R ^b10 each independently represent a C _1-36 aliphatic hydrocarbon group or a C _3-36 saturated cyclic hydrocarbon group, or form a ring with S; —CH ₂ — contained in the ring may be replaced by —O— or —S—.
R ^b11 represents a hydrogen atom, a C _1-36 aliphatic hydrocarbon group, or a C _3-36 saturated cyclic hydrocarbon group.
R ^b12 represents a C _6-18 aromatic hydrocarbon group, and the hydrogen atom contained in the aromatic hydrocarbon group is a C _1-12 aliphatic hydrocarbon group, a C _1-12 alkoxy group, a nitro group, C _It may be substituted with a _3-18 saturated cyclic hydrocarbon group or an alkylcarbonyloxy group. ]

[2] The salt according to [1], wherein n is 1 or 2.

[3] The salt according to [1] or [2], wherein n is 1.

[4] An acid generator containing the salt according to any one of [1] to [3].

[5] The acid generator according to [4] and a resin are contained, the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, and is dissolved in an alkaline aqueous solution by the action of an acid. Resist composition which is resin which can be done.

[6] The resist composition according to [5], which contains a basic compound.

[7] (1) A step of applying the resist composition according to [5] or [6] on a substrate,
(2) The process of drying the composition after application | coating and forming 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 line edge roughness can be formed using a resist composition containing the salt.

［式（Ｉ）中、Ｑ^１及びＱ^２は、それぞれ独立に、フッ素原子又はＣ_1-6ペルフルオロアルキル基を表す。
ｎは１〜３の整数を表す。
Ｚ⁺は、式（ｂ２−１）で表されるカチオン、式（ｂ２−２）で表されるカチオン又は式（ｂ２−３）で表されるカチオンを表す。］

［式（ｂ２−１）中、Ｒ^b4〜Ｒ^b6は、それぞれ独立に、Ｃ_1-30脂肪族炭化水素基、Ｃ_3-36飽和環状炭化水素基又はＣ_6-18芳香族炭化水素基を表し、該芳香族炭化水素基に含まれる水素原子は、ハロゲン原子、ヒドロキシ基、Ｃ_1-36脂肪族炭化水素基、Ｃ_3-36飽和環状炭化水素基又はＣ_1-12アルコキシ基で置換されていてもよい。但し、Ｒ^b4〜Ｒ^b6の少なくとも１つは、Ｃ_6-18芳香族炭化水素基を表す。］

［式（ｂ２−２）中、Ｒ^b7及びＲ^b8は、それぞれ独立に、ヒドロキシ基、Ｃ_1-12脂肪族炭化水素基又はＣ_1-12アルコキシ基を表す。
ｍ２及びｎ２は、それぞれ独立に０〜５の整数を表す。ｍ２が２以上である場合、複数のＲ^b7は同じであっても異なっていてもよく、ｎ２が２以上である場合、複数のＲ^b8は同じであっても異なっていてもよい。］

［式（ｂ２−３）中、Ｒ^b9及びＲ^b10は、それぞれ独立に、Ｃ_1-36脂肪族炭化水素基又はＣ_3-36飽和環状炭化水素基を表すか、Ｓとともに環を形成し、該環に含まれる−ＣＨ_２−は、−Ｏ−又は−Ｓ−で置き換わっていてもよい。
Ｒ^b11は、水素原子、Ｃ_1-36脂肪族炭化水素基又はＣ_3-36飽和環状炭化水素基を表す。
Ｒ^b12は、Ｃ_6-18芳香族炭化水素基を表し、該芳香族炭化水素基に含まれる水素原子は、Ｃ_1-12脂肪族炭化水素基、Ｃ_1-12アルコキシ基、ニトロ基、Ｃ_3-18飽和環状炭化水素基又はアルキルカルボニルオキシ基で置換されていてもよい。］ <Salt represented by formula (I)>

[In Formula (I), Q ¹ and Q ² each independently represents a fluorine atom or a C _1-6 perfluoroalkyl group.
n represents an integer of 1 to 3.
Z ⁺ represents a cation represented by the formula (b2-1), a cation represented by the formula (b2-2), or a cation represented by the formula (b2-3). ]

[In formula (b2-1), R ^{b4 to} R ^b6 each independently represents a C _1-30 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group. A hydrogen atom contained in the aromatic hydrocarbon group is substituted with a halogen atom, a hydroxy group, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _1-12 alkoxy group It may be. However, at least one of R ^{b4 to} R ^b6 represents a C _6-18 aromatic hydrocarbon group. ]

[In Formula (b2-2), R ^b7 and R ^b8 each independently represent a hydroxy group, a C _1-12 aliphatic hydrocarbon group, or a C _1-12 alkoxy group.
m2 and n2 each independently represent an integer of 0 to 5. When m2 is 2 or more, the plurality of R ^b7 may be the same or different, and when n2 is 2 or more, the plurality of R ^b8 may be the same or different. ]

[In Formula (b2-3), R ^b9 and R ^b10 each independently represent a C _1-36 aliphatic hydrocarbon group or a C _3-36 saturated cyclic hydrocarbon group, or form a ring with S; —CH ₂ — contained in the ring may be replaced by —O— or —S—.
R ^b11 represents a hydrogen atom, a C _1-36 aliphatic hydrocarbon group, or a C _3-36 saturated cyclic hydrocarbon group.
R ^b12 represents a C _6-18 aromatic hydrocarbon group, and the hydrogen atom contained in the aromatic hydrocarbon group is a C _1-12 aliphatic hydrocarbon group, a C _1-12 alkoxy group, a nitro group, C _It may be substituted with a _3-18 saturated cyclic hydrocarbon group or an alkylcarbonyloxy group. ]

Q ¹ and Q ² each independently represents a fluorine atom or a C _1-6 perfluoroalkyl group. Examples of the perfluoroalkyl group include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group, and a perfluorohexyl group. . Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.

  n is preferably 1 or 2, and n is more preferably 1.

［式中、Ｚ^＋、Ｑ^１及びＱ^２は、前記と同じ意味を表す。］ The salt represented by the formula (I) is preferably a salt represented by the following.

[Wherein Z ⁺ , Q ¹ and Q ² represent the same meaning as described above. ]

Specific examples of the anion represented by the formula (I) include the following.

Z ⁺ represents a cation represented by the formula (b2-1), a cation represented by the formula (b2-2), or a cation represented by the formula (b2-3).

［式（ｂ２−１）中、Ｒ^b4〜Ｒ^b6は、それぞれ独立に、Ｃ_1-30脂肪族炭化水素基、Ｃ_3-36飽和環状炭化水素基又はＣ_6-18芳香族炭化水素基を表し、該芳香族炭化水素基に含まれる水素原子は、ハロゲン原子、ヒドロキシ基、Ｃ_1-36脂肪族炭化水素基、Ｃ_3-36飽和環状炭化水素基又はＣ_1-12アルコキシ基で置換されていてもよい。但し、Ｒ^b4〜Ｒ^b6の少なくとも１つは、Ｃ_6-18芳香族炭化水素基を表す。］

［式（ｂ２−２）中、Ｒ^b7及びＲ^b8は、それぞれ独立に、ヒドロキシ基、Ｃ_1-12脂肪族炭化水素基又はＣ_1-12アルコキシ基を表す。
ｍ２及びｎ２は、それぞれ独立に０〜５の整数を表す。ｍ２が２以上である場合、複数のＲ^b7は同じであっても異なっていてもよく、ｎ２が２以上である場合、複数のＲ^b8は同じであっても異なっていてもよい。］

［式（ｂ２−３）中、Ｒ^b9及びＲ^b10は、それぞれ独立に、Ｃ_1-36脂肪族炭化水素基又はＣ_3-36飽和環状炭化水素基を表すか、Ｓとともに環を形成し、該環に含まれる−ＣＨ_２−は、−Ｏ−又は−Ｓ−で置き換わっていてもよい。
Ｒ^b11は、水素原子、Ｃ_1-36脂肪族炭化水素基又はＣ_3-36飽和環状炭化水素基を表す。
Ｒ^b12は、Ｃ_6-18芳香族炭化水素基を表し、該芳香族炭化水素基に含まれる水素原子は、Ｃ_1-12脂肪族炭化水素基、Ｃ_1-12アルコキシ基、ニトロ基、Ｃ_3-18飽和環状炭化水素基又はアルキルカルボニルオキシ基で置換されていてもよい。］

[In formula (b2-1), R ^{b4 to} R ^b6 each independently represents a C _1-30 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group. A hydrogen atom contained in the aromatic hydrocarbon group is substituted with a halogen atom, a hydroxy group, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _1-12 alkoxy group It may be. However, at least one of R ^{b4 to} R ^b6 represents a C _6-18 aromatic hydrocarbon group. ]

[In Formula (b2-2), R ^b7 and R ^b8 each independently represent a hydroxy group, a C _1-12 aliphatic hydrocarbon group, or a C _1-12 alkoxy group.
m2 and n2 each independently represent an integer of 0 to 5. When m2 is 2 or more, the plurality of R ^b7 may be the same or different, and when n2 is 2 or more, the plurality of R ^b8 may be the same or different. ]

[In Formula (b2-3), R ^b9 and R ^b10 each independently represent a C _1-36 aliphatic hydrocarbon group or a C _3-36 saturated cyclic hydrocarbon group, or form a ring with S; —CH ₂ — contained in the ring may be replaced by —O— or —S—.
R ^b11 represents a hydrogen atom, a C _1-36 aliphatic hydrocarbon group, or a C _3-36 saturated cyclic hydrocarbon group.
R ^b12 represents a C _6-18 aromatic hydrocarbon group, and the hydrogen atom contained in the aromatic hydrocarbon group is a C _1-12 aliphatic hydrocarbon group, a C _1-12 alkoxy group, a nitro group, C _It may be substituted with a _3-18 saturated cyclic hydrocarbon group or an alkylcarbonyloxy 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 alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, n-hexoxy, heptoxy, octoxy Group, 2-ethylhexyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group and the like. Examples of the ring formed by combining R ^b9 and R ^b10 together with S include, for example, a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathian-4-ium ring. Etc.

  Among cations represented by formula (b2-1), cations represented by formula (b2-2), and cations represented by formula (b2-3), cations represented by formula (b2-1) Is preferable, a cation represented by the formula (b2-1-1) is more preferable, and a triphenylsulfonium cation (v2 = w2 = x2 = 0 in the formula (b2-1-1) is more preferable.

In formula (b2-1-1), R ^{b19 to} R ^b21 each independently represent a halogen atom, a hydroxy group, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or C _{1- 12} represents an alkoxy group. The aliphatic hydrocarbon group preferably has 1 to 12 carbon atoms, and the saturated cyclic hydrocarbon group preferably has 4 to 36 carbon atoms. v2 to x2 each independently represents an integer of 0 to 5 (preferably 0 or 1). When any one of v2 to x2 is 2 or more, any one of the plurality of R ^{b19 to} R ^b21 may be the same as or different from each other.

R ^{b19 to} R ^b21 in formula (b2-1-1) are preferably each independently a halogen atom (more preferably a fluorine atom), a hydroxy group, a C _1-12 alkyl group, or a C _1-12 alkoxy. And v2 to x2 each independently represents an integer of 0 to 5 (preferably 0 or 1).

  Specific examples of the cation represented by the formula (b2-1) include the following.

  Specific examples of the cation represented by the formula (b2-2) include the following.

  Specific examples of the cation represented by the formula (b2-3) include the following.

  The salt represented by the formula (I) is a combination of the above-mentioned anions and cations. The above-mentioned anions and cations can be arbitrarily combined.

As the salt represented by the formula (I), the following salts are preferable.

As a manufacturing method of the salt represented by Formula (I), the manufacturing method represented by the following reaction formula is mentioned, for example.

By reacting a salt represented by the formula (I-aa) obtained by the method described in JP-A-2008-13551 with ammonia and represented by the formula (I-1) where n = 1. A salt can be obtained.
Examples of the solvent include chloroform.
Further, the salt represented by the formula (I-1) where n = 1 and the compound represented by the formula (I-bb) obtained by the method described in JP-A-2008-127367 are subjected to dehydration condensation. Thus, a salt represented by the formula (I-2) where n = 2 can be obtained.
A sulfuric acid etc. are mentioned as a dehydration condensation catalyst.
By dehydrating condensation of a salt represented by the formula (I-2) where n = 2 and a compound represented by the formula (I-bb) obtained by the method described in JP-A-2008-127367 , N = 3, a salt represented by the formula (I-3) can be obtained.

  The acid generator of the present invention contains a salt represented by the formula (I). When used as an acid generator, the salt represented by the formula (I) may be used alone or in combination of two or more. 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 An anion contained in the salt represented by (I) and a salt composed of a known cation may be included.

  The resist composition of the present invention contains an acid generator containing a salt represented by the formula (I) and a resin. The resin here is a resin that has an acid labile group, is insoluble or hardly soluble in an aqueous alkali solution, and can be dissolved in an aqueous alkali solution by the action of an acid. In this resist composition, an acid is generated from the salt represented by the formula (I) by exposure. The acid catalyzes and cleaves the acid labile group in the resin, making the resin soluble in an aqueous alkaline solution. Such a resist composition is suitable as a chemically amplified positive resist composition. However, in the resist composition of the present invention, 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 in the resist composition is preferably in the range of about 0.1 to 40% by weight in the solid content of the resist composition.

<Resin (hereinafter sometimes referred to as “resin (A)”)>
Resin (A) is a resin having an acid labile group and insoluble or hardly soluble in an aqueous alkali solution, and can be dissolved in an aqueous alkaline solution by the action of an acid, that is, an alkali capable by the action of an acid. It is a resin that dissolves. Resin (A) can be produced by polymerizing a monomer having an acid labile group (hereinafter sometimes referred to as “monomer having an acid labile group (a1)”). It becomes melted. The phrase “becomes soluble in an alkali by the action of an acid” means “being insoluble or hardly soluble in an alkaline aqueous solution before contact with an acid, but soluble in an alkaline aqueous solution after contact with an acid”. . As the monomer (a1) having an acid labile group, one type may be used alone, or two or more types may be used in combination.

<Monomer (a1) having an acid labile group>
The “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 (1) in which —O— is bonded to a tertiary carbon atom (excluding a bridgehead carbon atom of a bridged cyclic hydrocarbon group) (ie, Ester bond having a tertiary alcohol residue). Hereinafter, the group represented by the formula (1) may be referred to as “acid-labile group (1)”.

In formula (1), R ^{a1 to} R ^a3 each independently represents an aliphatic hydrocarbon group or a saturated cyclic hydrocarbon group, or R ^a1 and R ^a2 may be bonded to each other. * Represents a bond.

Examples of the acid labile group (1) include a 1,1-dialkylalkoxycarbonyl group (in the group (1), R ^{a1 to} R ^a3 are alkyl groups, preferably a tert-butoxycarbonyl group), 2 -Alkyl-2-adamantyloxycarbonyl group (in formula (1), wherein R ^a1 , R ^a2 and a carbon atom form an adamantyl group, and R ^a3 is an alkyl group), and 1- (1-adamantyl)- 1-alkylalkoxycarbonyl groups (in the formula (1), R ^a1 and R ^a2 are alkyl groups and R ^a3 is an adamantyl group) and the like.

The monomer (a1) having an acid labile group is preferably a monomer having an acid labile group (1) and a carbon-carbon double bond, more preferably an acid labile group (1). (Meth) acrylic monomer having In the present specification, "(meth) acrylic monomer" means "CH ₂ = CH-CO-" or _{"CH 2 = C (CH 3)} -CO- " at least one monomer having the structure To do. Similarly, “(meth) acrylate” and “(meth) acrylic acid” mean “at least one of acrylate and methacrylate” and “at least one of acrylic acid and methacrylic acid”, respectively.

Among the (meth) acrylic monomers having the acid labile group (1), those having a C _5-20 saturated cyclic hydrocarbon group are preferred. If a resin obtained by polymerizing the monomer (a1) having a bulky structure such as a saturated cyclic hydrocarbon group is used, the resolution of the resist can be improved. The saturated cyclic hydrocarbon group may be monocyclic or polycyclic. Examples of the monocyclic saturated cyclic hydrocarbon group include a cycloalkyl group (for example, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group). Examples of the polycyclic saturated cyclic hydrocarbon group include a group obtained by hydrogenating a condensed aromatic hydrocarbon group (for example, a hydronaphthyl group), a bridged cyclic hydrocarbon group (for example, an adamantyl group, a norbornyl group), and the like. . In addition, a group having a shape in which a bridged ring (for example, norbornane ring) and a single ring (for example, cycloheptane ring or cyclohexane ring) or a polycycle (for example, decahydronaphthalene ring) are condensed, or A group having a condensed shape is also included in the saturated cyclic hydrocarbon group.

  Among the (meth) acrylic monomers having the acid labile group (1) and the saturated cyclic hydrocarbon group, the acid labile group represented by the formula (a1-1) or the formula (a1-2) Monomers having are preferred. These may be used alone or in combination of two or more.

In formula (a1-1) and formula (a1-2), L ^a1 and L ^a2 each independently represent —O— or ^* —O— (CH ₂ ) _k1 —CO—O—, and k1 represents 1 Represents an integer of ˜7, and ^* represents a bond with —CO—.
R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group. R ^a6 and R ^a7 each independently represent a C _1-8 aliphatic hydrocarbon group or a C _3-10 saturated cyclic hydrocarbon group, m1 represents an integer of 0-14, and n1 represents 0-10. Represents an integer. The chemical formula in this specification includes stereoisomers.

L ^a1 and L ^a2 are preferably —O— or ^* —O— (CH ₂ ) _f1 —CO—O— (wherein f1 is an integer of 1 to 4), more preferably —O—. It is.

R ^a4 and R ^a5 are preferably methyl groups. The carbon number of the aliphatic hydrocarbon group of R ^a6 and R ^a7 is preferably 6 or less, and the carbon number of the saturated cyclic hydrocarbon group is preferably 8 or less, more preferably 6 or less. Examples of the aliphatic hydrocarbon group represented by R ^a6 and R ^a7 include a methyl group, an ethyl group, a 1-methylethyl group (isopropyl group), a 1,1-dimethylethyl group (tert-butyl group), and 2,2-dimethyl. Ethyl 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, Examples include pentyl group, 1-methylpentyl group, hexyl group, 1,4-dimethylhexyl group, heptyl group, 1-methylheptyl group, octyl group and the like. Examples of the saturated cyclic hydrocarbon group for R ^a6 and R ^a7 include a cycloheptyl group, a methylcycloheptyl group, a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a norbornyl group, and a methylnorbornyl group.

  m1 is preferably an integer of 0 to 3, more preferably 0 or 1. n1 is 0, preferably an integer of 0 to 3, more preferably 0 or 1. k1 is preferably an integer of 1 to 4, more preferably 1.

  Examples of the monomer (a1-1) having an adamantyl group include the following, among which 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, and 2-Isopropyl-2-adamantyl (meth) acrylate is preferred, and the methacrylate form is more preferred.

  Examples of the monomer (a1-2) having a cyclohexyl group include the following, among which 1-ethyl-1-cyclohexyl (meth) acrylate is preferable, and 1-ethyl-1-cyclohexyl methacrylate is more preferable. preferable.

  The content of the structural unit derived from the monomer represented by the formula (a1-1) or the formula (a1-2) in the resin is usually 10 to 95 mol%, preferably 15 to 90, in all units of the resin. It is mol%, More preferably, it is 20-85 mol%.

  Examples of the monomer having an acid labile group (1) and a carbon-carbon double bond include a monomer having a norbornene ring represented by the formula (a1-3). Since the resin having a structural unit derived from the monomer (a1-3) having an acid labile group has a bulky structure, the resolution of the resist can be improved. Furthermore, the monomer (a1-3) having an acid labile group can improve the resistance to dry etching of a resist by introducing a rigid norbornane ring into the main chain of the resin.

In formula (a1-3), R ^a9 represents a hydrogen atom, a C _1-3 aliphatic hydrocarbon group, a carboxy group, a cyano group, or an alkoxycarbonyl group (which may have a substituent (for example, a hydroxy group)). -COOR ^a13 ), R ^a13 represents a C _1-8 aliphatic hydrocarbon group or a C _3-8 saturated cyclic hydrocarbon group, and the hydrogen atoms of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group are It may be substituted with a hydroxy group, and —CH ₂ — in the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group may be replaced with —O— or —CO—. R ^{a10 to} R ^a12 each independently represents a C _1-12 aliphatic hydrocarbon group or a C _3-12 saturated cyclic hydrocarbon group, or R ^a10 and R ^a11 may be bonded to each other, The hydrogen atom of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group may be substituted with a hydroxy group or the like, and —CH ₂ — of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group is —O— or It may be replaced by -CO-.

Examples of the aliphatic hydrocarbon group which may have a substituent for R ^a9 include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group. ^Examples of R ^a13 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 ^{a10 to} R ^a12 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 the saturated cyclic hydrocarbon group formed by R ^a10 , R ^a11 and the carbon to which they are bonded include a cyclohexyl group and an adamantyl group.

  Examples of the monomer (a1-3) having a norbornene ring include, for example, 5-norbornene-2-carboxylic acid-tert-butyl, 5-norbornene-2-carboxylic acid 1-cyclohexyl-1-methylethyl, 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-adap Pentyl) -1-methylethyl and the like.

  The content rate of the structural unit derived from the monomer represented by the formula (a1-3) in the resin is usually 10 to 95 mol%, preferably 15 to 90 mol%, more preferably in all units of the resin. Is 20 to 85 mol%.

［式（ａ１−４）中、Ｒ¹⁰は、水素原子、ハロゲン原子又はハロゲン原子を有してもよいＣ_1-6アルキル基を表す。
Ｒ¹¹は、それぞれ独立に、ハロゲン原子、水酸基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、Ｃ_2-4アシル基、Ｃ_2-4アシルオキシ基、アクリロイル基又はメタクリロイル基を表す。
ｌ^ａは０〜４の整数を表す。ｌ^ａが２以上の整数である場合、複数のＲ¹¹は同一の種類の基であっても異なる種類の基であってもよい。
Ｒ¹²及びＲ¹³はそれぞれ独立に、水素原子又はＣ_1-12炭化水素基を表す。
Ｘ^ａ２は、単結合又は置換基を有していてもよいＣ_1-17飽和炭化水素基を表し、該飽和炭化水素基に含まれる−ＣＨ_２−は−ＣＯ−、−Ｏ−、−Ｓ−、−ＳＯ_２−又は−Ｎ（Ｒ^ｃ）−で置き換わっていてもよい。Ｒ^ｃは、水素原子又はＣ_1-6アルキル基を表す。
Ｙ^ａ３は、Ｃ_1-12脂肪族炭化水素基、Ｃ_3-18飽和環状炭化水素基又はＣ_6-18芳香族炭化水素基であり、該脂肪族炭化水素基、飽和環状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い。］ Examples of the monomer having the acid labile group (1) and the carbon-carbon double bond include a monomer (a1-4) represented by the formula (a1-4).

[In formula (a1-4), R ¹⁰ represents a hydrogen atom, a halogen atom or a C _1-6 alkyl group which may have a halogen atom.
R ¹¹ each independently represents a halogen atom, a hydroxyl group, a C _1-6 alkyl group, a C _1-6 alkoxy group, a C _2-4 acyl group, a C _2-4 acyloxy group, an acryloyl group or a methacryloyl group.
l ^a represents an integer of 0 to 4; If l ^a is an integer of 2 or more, plural R ¹¹ may be the same kind a group even if different types of groups.
R ¹² and R ¹³ each independently represents a hydrogen atom or a C _1-12 hydrocarbon group.
X ^a2 represents a C _1-17 saturated hydrocarbon group which may have a single bond or a substituent, and —CH ₂ — contained in the saturated hydrocarbon group represents —CO—, —O—, —S. -, - SO ₂ - or -N ^{(R c)} - may be replaced by. R ^c represents a hydrogen atom or a C _1-6 alkyl group.
Y ^a3 is a C _1-12 aliphatic hydrocarbon group, a C _3-18 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group, and the aliphatic hydrocarbon group, saturated cyclic hydrocarbon group and aromatic The group hydrocarbon group may have a substituent. ]

Ｃ_6-18芳香族炭化水素基としては、例えば、フェニル基、ナフチル基、アントラニル基、ｐ−メチルフェニル基、ｐ−ｔｅｒｔ−ブチルフェニル基、ｐ−アダマンチルフェニル基等が挙げられる。 Examples of the C _1-6 alkyl group which 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, A perfluoropentyl group, a perfluorohexyl group, etc. are mentioned. Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.
Examples of the C _1-6 alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. A C _1-4 alkyl group is preferred, a C _1-2 alkyl group is more preferred, and a methyl group is particularly preferred.
Examples of the C _1-6 alkoxy group include 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, and an n-hexoxy group. A C _1-4 alkoxy group is preferable, a C _1-2 alkoxy group is more preferable, and a methoxy group is particularly preferable.
Examples of the C _2-4 acyl group include acetyl, propionyl, butyryl and the like.
Examples of the C _2-4 acyloxy group include acetyloxy, propionyloxy, butyryloxy and the like.
Examples of the C _1-12 hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, Examples include 2-ethylhexyl group, cyclohexyl group, adamantyl group, 2-alkyl-2-adamantyl group, 1- (1-adamantyl) -1-alkyl group, isobornyl group and the like.
Examples of the C _1-12 aliphatic hydrocarbon group include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n- Examples include hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl and the like.
Examples of the C _3-18 saturated cyclic hydrocarbon group include 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 group, group shown below, etc. are mentioned.

Examples of the C _6-18 aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthranyl group, a p-methylphenyl group, a p-tert-butylphenyl group, and a p-adamantylphenyl group.

  As a monomer (a1-4), the following monomers are mentioned, for example.

  The content of the structural unit derived from the monomer represented by the formula (a1-4) in the resin is usually 10 to 95 mol%, preferably 15 to 90 mol%, more preferably in all units of the resin. Is 20 to 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.

  As the acid stable monomer, those having a hydroxy group or a lactone ring are preferred. Derived from an acid stable monomer having a hydroxy group (hereinafter referred to as “acid stable monomer having a hydroxy group (a2)”) or an acid stable monomer having a lactone ring (hereinafter referred to as “acid stable monomer having a lactone ring (a3)”) If a resin having a structural unit to be used is used, the resolution of the resist and the adhesion to the substrate can be improved.

<Acid-stable monomer having a hydroxy group (a2)>
When the resist composition is used for KrF excimer laser exposure (248 nm), high energy beam exposure such as electron beam or EUV light, the acid-stable monomer (a2) having a hydroxy group has an acid having a phenolic hydroxyl group which is a hydroxystyrene. It is preferable to use a stable monomer (a2-0). When using short wavelength ArF excimer laser exposure (193 nm) or the like, an acid stable monomer having a hydroxyadamantyl group represented by formula (a2-1) should be used as the acid stable monomer having a hydroxy group (a2). Is preferred. The acid-stable monomer (a2) having a hydroxy group may be used alone or in combination of two or more.

  Examples of the monomer (a2-0) having a phenolic hydroxyl group include styrene monomers such as p- or m-hydroxystyrene represented by the formula (a2-0).

［式（ａ２−０）中、
Ｒ^８は、水素原子、ハロゲン原子又はハロゲン原子を有してもよいＣ_1-6アルキル基を表す。
Ｒ^９は、ハロゲン原子、水酸基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、Ｃ_2-4アシル基、Ｃ_2-4アシルオキシ基、アクリロイル基又はメタクリロイル基を表す。
ｍａは０〜４の整数を表す。ｍａが２以上の整数である場合、複数のＲ^９は同一の種類の基であっても異なる種類の基であってもよい。］

[In the formula (a2-0),
R ⁸ represents a hydrogen atom, a halogen atom or a C _1-6 alkyl group which may have a halogen atom.
R ⁹ represents a halogen atom, a hydroxyl group, a C _1-6 alkyl group, a C _1-6 alkoxy group, a C _2-4 acyl group, a C _2-4 acyloxy group, an acryloyl group or a methacryloyl group.
ma represents an integer of 0 to 4. When ma is an integer of 2 or more, the plurality of R ⁹ may be the same type of group or different types of groups. ]

Examples of the C _1-6 alkyl group which 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, A perfluoropentyl group, a perfluorohexyl group, etc. are mentioned. Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.
Examples of the C _1-6 alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. A C _1-4 alkyl group is preferred, a C _1-2 alkyl group is more preferred, and a methyl group is particularly preferred.
Examples of the C _1-6 alkoxy group include 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, and an n-hexoxy group. A C _1-4 alkoxy group is preferable, a C _1-2 alkoxy group is more preferable, and a methoxy group is particularly preferable.
Examples of the C _2-4 acyl group include acetyl, propionyl, butyryl and the like.
Examples of the C _2-4 acyloxy group include acetyloxy, propionyloxy, butyryloxy and the like.

When obtaining a copolymer resin having a structural unit derived from a monomer having such a phenolic hydroxyl group, the corresponding (meth) acrylic acid ester monomer, acetoxystyrene, and styrene are radically polymerized and then deacetylated with an acid. Can be obtained.
Examples of the monomer having a phenolic hydroxyl group include the following monomers.

  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 (a2-0) in the resin is usually from 5 to 90 mol%, preferably from 10 to 85 mol%, more preferably, in all units of the resin. Is 15 to 80 mol%.

  Examples of the acid stable monomer having a hydroxyadamantyl group include a monomer represented by the formula (a2-1).

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

L ^a3 is preferably —O—, ^* —O— (CH ₂ ) _f1 —CO—O— (wherein f1 is an integer of 1 to 4), more preferably —O—. R ^a14 is preferably a methyl group. R ^a15 is preferably a hydrogen atom. R ^a16 is preferably a hydrogen atom or a hydroxy group. o1 is preferably an integer of 0 to 3, more preferably 0 or 1.

  Examples of the acid-stable monomer (a2-1) having a hydroxyadamantyl group include the following. Among these, 3-hydroxy-1-adamantyl (meth) acrylate, 3,5-dihydroxy-1-adamantyl ( 1- (3,5-dihydroxy-1-adamantyloxycarbonyl) methyl (meth) acrylate and (meth) acrylate are preferred, and 3-hydroxy-1-adamantyl (meth) acrylate and 3,5-dihydroxy-1-adamantyl ( (Meth) acrylate is more preferable, and 3-hydroxy-1-adamantyl methacrylate and 3,5-dihydroxy-1-adamantyl methacrylate are more preferable.

  The content of the structural unit derived from the monomer represented by the formula (a2-1) in the resin is usually 3 to 40 mol%, preferably 5 to 35 mol%, more preferably, in all units of the resin. Is 5 to 30 mol%.

<Acid-stable monomer having a lactone ring (a3)>
The lactone ring possessed by the acid-stable monomer (a3) may be a monocycle such as a β-propiolactone ring, γ-butyrolactone ring, or δ-valerolactone ring, or 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 (a3) having a lactone ring is preferably represented by the formula (a3-1), the formula (a3-2) or the formula (a3-3). These 1 type may be used independently and may use 2 or more types together.

In formula (a3-1) to formula (a3-3), L ^{a4 to} L ^a6 each independently represent —O— or ^* —O— (CH ₂ ) _k3 —CO—O—, and k3 represents 1 Represents an integer of ˜7, and ^* represents a bond with —CO—. R ^{a18 to} R ^a20 each independently represents a hydrogen atom or a methyl group. R ^a21 represents a C _1-4 aliphatic hydrocarbon group, and p1 represents an integer of 0 to 5. R ^a22 and R ^a23 each independently represent a carboxy group, a cyano group or a C _1-4 aliphatic hydrocarbon group, and q1 and r1 each independently represent an integer of 0 to 3. When p1, q1 or r1 is 2 or more, a plurality of R ^a21 , R ^a22 or R ^a23 may be the same as or different from each other.

Examples of L ^{a4 to} L ^a6 include those described for L ^a3 . L ^{a4 to} L ^a6 are each independently preferably —O—, ^* —O— (CH ₂ ) _d1 —CO—O— (the d1 is an integer of 1 to 4), more preferably. Is —O—.
R ^{a18 to} R ^a20 are preferably methyl groups. R ^a21 is preferably a methyl group. R ^a22 and R ^a23 are each independently preferably a carboxy group, a cyano group or a methyl group. p1 to r1 are each independently preferably 0 to 2, more preferably 0 or 1.

  Examples of the acid stable monomer (a3-1) having a γ-butyrolactone ring include the following.

  As the acid stable monomer (a3-1) having a γ-butyrolactone ring, an acid labile monomer can also be exemplified. For example, the following are mentioned.

  Examples of the acid stable monomer (a3-2) having a condensed ring of γ-butyrolactone ring and norbornane ring include the following.

  As the acid stable monomer (a3-2) having a condensed ring of γ-butyrolactone ring and norbornane ring, an acid labile monomer can be exemplified. For example, the following are mentioned.

  Examples of the acid stable monomer (a3-3) having a condensed ring of γ-butyrolactone ring and cyclohexane ring include the following.

  An acid labile monomer can also be exemplified as the monomer (a3-3) having a condensed ring of γ-butyrolactone ring and cyclohexane ring. For example, the following are mentioned.

Among acid-stable monomers (a3) having a lactone ring, (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 rate of the structural unit derived from the monomer represented by the formula (a3-1), the formula (a3-2) or the formula (a3-3) in the resin is usually 5 to 50 mol% in all the units of the resin. Yes, preferably 10 to 45 mol%, more preferably 15 to 40 mol%.

<Other acid stable monomers (a4)>
Examples of the other acid stable monomer (a4) include maleic anhydride represented by formula (a4-1), itaconic anhydride represented by formula (a4-2), and formula (a4-3). And acid-stable monomers having a norbornene ring.

In formula (a4-3), R ^a25 and R ^a26 each independently represent a hydrogen atom, a C _1-3 aliphatic hydrocarbon group ^optionally having a substituent (for example, a hydroxy group), a cyano group, or a carboxy group. R ^a25 and R ^a26 are bonded to each other to form —CO—O—CO—, and R ^a27 is a C _1-36 aliphatic hydrocarbon group, or an alkoxycarbonyl group (—COOR ^a27 ), Alternatively, it represents a C _3-36 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 ^a27 is an acid labile group are excluded (that is, R ^a27 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 ^a25 and R ^a26 include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group. The carbon number of the aliphatic hydrocarbon group of R ^a27 is preferably 1 to 8, more preferably 1 to 6, and the saturated cyclic hydrocarbon group preferably has 4 to 36, more preferably 4 to 12 carbon atoms. is there. ^Examples of R ^a27 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 (a4-3) having a norbornene ring include 2-norbornene, 2-hydroxy-5-norbornene, 5-norbornene-2-carboxylic acid, methyl 5-norbornene-2-carboxylate, and 5-norbornene. Examples include 2-hydroxy-1-ethyl-2-carboxylate, 5-norbornene-2-methanol, 5-norbornene-2,3-dicarboxylic acid anhydride, and the like.

  The content of the structural unit derived from the monomer represented by the formula (a4-1), the formula (a4-2) or the formula (a4-3) in the resin is usually 2 to 40 mol% in all the 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 (a1) having an acid labile group, an acid stable monomer (a2) having a hydroxy group, and / or an acid stable monomer (a3) having a lactone ring. It is a polymer. In this preferred copolymer, the monomer (a1) having an acid labile group is more preferably at least one of a monomer (a1-1) having an adamantyl group and a monomer (a1-2) having a cyclohexyl group. A species (more preferably a monomer (a1-1) having an adamantyl group), and an acid stable monomer (a2) having a hydroxy group, preferably an acid stable monomer (a2-1) having a hydroxyadamantyl group, and a lactone The acid-stable monomer (a3) having a ring is more preferably an acid-stable monomer (a3-1) having a γ-butyrolactone ring and an acid-stable monomer (a3-2) 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).

  It is preferable that the content rate of resin (A) is 80 mass% or more in solid content of a resist composition. In the present specification, the “solid content in the resist composition” means the total of the resist composition components excluding the solvent (E). The solid content in the resist 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 contains 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 the formula (C2), Ar ^c1 represents an aromatic hydrocarbon group. R ^c5 and R ^c6 each independently represent a hydrogen atom, an aliphatic hydrocarbon group (preferably an alkyl group or a cycloalkyl group), a saturated cyclic hydrocarbon group or an aromatic hydrocarbon group. However, the hydrogen atom of the aliphatic hydrocarbon group, the saturated cyclic hydrocarbon group or the aromatic hydrocarbon group may be substituted with a hydroxy group, an amino group, or a C _1-6 alkoxy group, and the amino group _May be substituted with a C _1-4 alkyl group. The carbon number of the aliphatic hydrocarbon group is preferably about 1 to 6, the carbon number of the saturated cyclic hydrocarbon group is preferably about 5 to 10, and the carbon number of the aromatic hydrocarbon group is Preferably, it is about 6-10.

In formula (C2-1), R ^c5 and R ^c6 are the same as described above. R ^c7 represents an aliphatic hydrocarbon group (preferably an alkyl group or a cycloalkyl group), an alkoxy group, a saturated cyclic hydrocarbon group, or an aromatic hydrocarbon group. However, the hydrogen atom of an aliphatic hydrocarbon group, an alkoxy group, a saturated cyclic hydrocarbon group, and an aromatic hydrocarbon group may have the substituent demonstrated by Formula (C2). m3 represents an integer of 0 to 3. When m3 is 2 or more, the plurality of R ^c7 may be the same as or different from each other. Aliphatic hydrocarbon group R ^c7, preferable number of carbon atoms of the saturated cyclic hydrocarbon group and the aromatic hydrocarbon group are the same as those of the formula (C2), the carbon number of the alkoxy group R ^c7 is independently in, preferably 1 It is about ~ 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. Of these, diisopropylaniline (particularly 2,6-diisopropylaniline) is preferable.

  Moreover, as a basic compound (C), the compound represented by Formula (C3)-Formula (C11) is mentioned.

R ^c8 in formula (C3) represents any of the groups described for R ^c7 in formula (C2). R ^c9 , R ^c10 , R ^{c11 to} R ^c14 , R ^{c16 to} R ^c19 and R ^c22 bonded to the nitrogen atom in formula (C3) to formula (C8) are each independently R ^{c5 in} formula (C2) and It represents one of the groups described for R ^c6 . R ^c20 , R ^c21 and R ^{c23 to} R ^c28 bonded to the aromatic carbon in formula (C7) to formula (C11) are each independently any group described for R ^c7 in formula (C2-1) Represents. O3 to u3 in Formula (C7) and Formula (C9) to Formula (C11) each independently represents an integer of 0 to 3. When any of o3 to u3 is 2 or more, any of the plurality of R ^{c20 to} R ^c28 may be the same as or different from each other.

R ^c15 in formula (C6) represents an aliphatic hydrocarbon group, a saturated cyclic hydrocarbon group, or an alkanoyl group, and n3 represents an integer of 0 to 8. When n3 is 2 or more, the plurality of R ^c15 may be the same as or different from each other. The number of carbon atoms of the aliphatic hydrocarbon group R ^c15 is preferably about 1 to 6 carbon atoms in the saturated cyclic hydrocarbon group R ^c15 is preferably about 3 to 6, alkanoyl group R ^c15 Preferably carbon number is about 2-6.

L ^c1 and L ^{c2 in} formula (C7) and formula (C10) are each independently a divalent aliphatic hydrocarbon group (preferably an alkylene group), —CO—, —C (═NH) —, —C (= NR ^c3 )-, -S-, -SS-, or a combination thereof. The divalent aliphatic hydrocarbon group preferably has about 1 to 6 carbon atoms. R ^c3 represents a C _1-4 alkyl 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 (sometimes referred to as "solvent (E)")
The resist composition of the present invention may contain the solvent (E) in an amount of 90% by mass or more in the composition. The resist composition of the present invention containing the solvent (E) is suitable for producing a thin film resist. The content rate of a solvent (E) is 90 mass% or more (preferably 92 mass% or more, more preferably 94 mass% or more) in a composition, and 99.9 mass% or less (preferably 99 mass% or less). The content rate of a solvent (E) can be measured by well-known analysis means, such as a liquid chromatography or a gas chromatography, for example.

  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. Moreover, the compound which has an alicyclic hydrocarbon skeleton of Unexamined-Japanese-Patent No. 2003-280200, for example, pinacol diadamantylate, etc. may be included.

<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) The process of drying the composition after application | coating and forming 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 composition after application is dried to remove the solvent. 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, 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.

<Application>
The resist composition containing the salt of the present invention is particularly useful for a chemically amplified photoresist composition, microfabrication of semiconductors, 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, since the line edge roughness of the obtained pattern can be further improved, as a chemically amplified photoresist composition suitable for excimer laser lithography such as ArF and KrF, ArF immersion exposure lithography, electron beam lithography, and EUV exposure lithography. Can be used. 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)

A salt represented by the formula (B1-a) was synthesized by the method described in Synthesis Example 6 of JP-A-2008-13551.
19.30 parts of the salt represented by the formula (B1-a), 80.70 parts of chloroform and 90.80 parts of 4% ammonia-methanol solution were charged and stirred at 23 ° C. for 48 hours. After concentrating the obtained reaction product, 50.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 10.00 parts of acetonitrile and tert-butyl methyl ether 40 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 10.00 parts of acetonitrile and 50.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the obtained residue, 10.00 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. This operation was performed three times. The obtained residue was dissolved in chloroform and concentrated to obtain 10.70 parts of a salt represented by the formula (B1) as an oily substance.

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 174.0

Example 2: Synthesis of a salt represented by the formula (B2)

A salt represented by the formula (B2-a) was synthesized by the method described in Example 6 of JP-A-2008-127367.
1.15 parts of the salt represented by the formula (B2-a), 1.14 parts of the salt represented by the formula (B1), 23.80 parts of chloroform and 0.17 parts of sodium acetate were charged, and the mixture was heated at 80 ° C. for 2 hours. Refluxed. Acetic anhydride (22.57 parts) was added to the obtained reaction mass, and the mixture was further refluxed at 80 ° C. for 2 hours. The obtained reaction product was charged with 6.20 parts of chloroform and 15.00 parts of ion-exchanged water, and stirred and separated. Water washing was performed 6 times. After concentrating the obtained reaction product, 5.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 1.00 part of acetonitrile and tert-butyl methyl ether 4 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 1.00 parts of acetonitrile and 5.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the resulting residue, 2.00 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 0.42 part of a salt represented by the formula (B2) as an oily substance.

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (−) Spectrum): M ⁻ 330.9

Example 3: Synthesis of a salt represented by the formula (B3)

  21.09 parts of the salt represented by the formula (B3-a), 88.16 parts of chloroform and 90.80 parts of 4% ammonia-methanol solution were charged and stirred at 23 ° C. for 48 hours. After concentrating the obtained reaction product, 50.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 10.00 parts of acetonitrile and tert-butyl methyl ether 40 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 10.00 parts of acetonitrile and 50.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the obtained residue, 10.00 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. This operation was performed three times. The obtained residue was dissolved in chloroform and concentrated to obtain 10.98 parts of the salt represented by the formula (B3).

MS (ESI (+) Spectrum): M ⁺ 305.1
MS (ESI (-) Spectrum): M ^- 174.0

Example 4: Synthesis of salt represented by formula (B4)

  1.26 parts of a salt represented by the formula (B4-a), 1.25 parts of a salt represented by the formula (B3), 26.10 parts of chloroform and 0.17 parts of sodium acetate are charged and the mixture is heated at 80 ° C. for 2 hours. Refluxed. Acetic anhydride (22.57 parts) was added to the obtained reaction mass, and the mixture was further refluxed at 80 ° C. for 2 hours. To the obtained reaction product, 3.90 parts of chloroform and 15.00 parts of ion-exchanged water were added, and the mixture was stirred and separated. Water washing was performed 6 times. After concentrating the obtained reaction product, 5.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 1.00 part of acetonitrile and tert-butyl methyl ether 4 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 1.00 parts of acetonitrile and 5.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the resulting residue, 2.00 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 0.44 parts of the salt represented by the formula (B4).

MS (ESI (+) Spectrum): M ⁺ 305.1
MS (ESI (−) Spectrum): M ⁻ 330.9

Example 5: Synthesis of salt represented by formula (B5)

  20.05 parts of the salt represented by the formula (B5-a), 83.81 parts of chloroform and 90.80 parts of 4% ammonia-methanol solution were charged and stirred at 23 ° C. for 48 hours. After concentrating the obtained reaction product, 50.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 10.00 parts of acetonitrile and tert-butyl methyl ether 40 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 10.00 parts of acetonitrile and 50.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the obtained residue, 10.00 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. This operation was performed three times. The obtained residue was dissolved in chloroform and concentrated, and the resulting concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain the formula (B5). 9.21 parts of the salt represented were obtained.

MS (ESI (+) Spectrum): M ⁺ 281.0
MS (ESI (-) Spectrum): M ^- 174.0

Example 6: Synthesis of salt represented by formula (B6)

  1.20 parts of a salt represented by the formula (B6-a), 1.19 parts of a salt represented by the formula (B5), 24.86 parts of chloroform and 0.17 parts of sodium acetate are charged and the mixture is heated at 80 ° C. for 2 hours. Refluxed. Acetic anhydride (22.57 parts) was added to the obtained reaction mass, and the mixture was further refluxed at 80 ° C. for 2 hours. To the obtained reaction product, 5.14 parts of chloroform and 15.00 parts of ion-exchanged water were added, and the mixture was stirred and separated. Water washing was performed 6 times. After concentrating the obtained reaction product, 5.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 1.00 part of acetonitrile and tert-butyl methyl ether 4 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 1.00 parts of acetonitrile and 5.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the resulting residue, 2.00 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 (B6). 0.33 part of the salt represented was obtained.

MS (ESI (+) Spectrum): M ⁺ 281.0
MS (ESI (−) Spectrum): M ⁻ 330.9

Example 7: Synthesis of salt represented by formula (B7)

  16.90 parts of the salt represented by the formula (B7-a), 70.66 parts of chloroform, and 90.80 parts of 4% ammonia-methanol solution were charged and stirred at 23 ° C. for 48 hours. After concentrating the obtained reaction product, 50.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 10.00 parts of acetonitrile and tert-butyl methyl ether 40 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 10.00 parts of acetonitrile and 50.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the obtained residue, 10.00 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. This operation was performed three times. The obtained residue was dissolved in chloroform and concentrated, and the resulting concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain the formula (B7). 5.71 parts of the salt represented were obtained.

MS (ESI (+) Spectrum): M ^<+> 207.1
MS (ESI (-) Spectrum): M ^- 174.0

Example 8: Synthesis of salt represented by formula (B8)

  1.00 parts of a salt represented by the formula (B8-a), 0.99 parts of a salt represented by the formula (B7), 20.70 parts of chloroform and 0.17 parts of sodium acetate are charged and the mixture is heated at 80 ° C. for 2 hours. Refluxed. Acetic anhydride (22.57 parts) was added to the obtained reaction mass, and the mixture was further refluxed at 80 ° C. for 2 hours. To the obtained reaction product, 9.30 parts of chloroform and 15.00 parts of ion-exchanged water were added, and the mixture was stirred and separated. Water washing was performed 5 times. After concentrating the obtained reaction product, 5.00 parts of acetonitrile was added to the resulting concentrate to dissolve, and then concentrated. To the resulting residue, 1.00 part of acetonitrile and tert-butyl methyl ether 4 were added. After adding 0.000 parts and stirring, it concentrated. To the obtained residue, 1.00 parts of acetonitrile and 5.00 parts of ethyl acetate were added and stirred, and the supernatant was removed. To the resulting residue, 2.00 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 the resulting concentrate is fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain the formula (B8). 0.18 part of the salt represented was obtained.

MS (ESI (+) Spectrum): M ^<+> 207.1
MS (ESI (−) Spectrum): M ⁻ 330.9

Synthesis Example 1: Synthesis of Resin A1 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 was purified by pouring it into a large amount of a mixed solvent of methanol and water (3: 1) and precipitating three times to obtain a copolymer having a weight average molecular weight of about 8,000 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 A1.

合成例２：樹脂Ａ２の合成
モノマーＥ、モノマーＦ、モノマーＢ、モノマーＣ及びモノマーＤを、モル比３０：１４：６：２０：３０の割合で仕込んだ。次いで、全モノマーの合計質量に対して、１．５質量倍のジオキサンを加えた。得られた混合物に、開始剤としてアゾビスイソブチロニトリルとアゾビス（２，４−ジメチルバレロニトリル）とを全モノマーの合計モル数に対して、それぞれ、１．００ｍｏｌ％と３．００ｍｏｌ％との割合で添加し、これを７３℃で約５時間加熱した。その後、反応液を、大量のメタノールと水との混合溶媒（４：１）に注いで沈殿させる操作を３回行うことにより精製し、重量平均分子量が約８．１×１０^３である共重合体を収率６５％で得た。得られた共重合体は、次式の各モノマーから導かれる構造単位を有するものであり、これを樹脂Ａ２とした。

Synthesis Example 2: Synthesis of Resin A2 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 A2.

Synthesis Example 3: Synthesis of Resin A3 Monomer A, Monomer B, Monomer C, and Monomer D were charged at a molar ratio of 35: 15: 20: 30, and then 1.5 mass with respect to the total mass of all monomers. Double the dioxane was added. Into the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) were used as initiators at a ratio of 1 mol% and 3 mol%, respectively, with respect to the total number of moles of all monomers. This was added and heated at 77 ° C. for about 5 hours. Thereafter, the reaction solution was purified by pouring it into a large amount of methanol / water mixed solvent and precipitating three times to obtain a copolymer having a weight average molecular weight of about 8.1 × 10 ³ in a yield of 78. %. The obtained copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin A3.

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

<Resin>
Resins A1 to A3
<Acid generator>
Acid generators B1 to B8: a salt represented by formula (B1) to a hydrochloric acid generator represented by formula (B8) H1: p-tolyldiphenylsulfonium perfluorooctane sulfonate acid generator H2:

<Basic compound: Quencher>
Quencher C1: 2,6-diisopropylaniline <additive>
Additive F1: Pinacol diadamantylate <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 Co., Ltd.] was applied onto a 12-inch silicon wafer and baked at 205 ° C. for 60 seconds to obtain a thickness of 780 mm. An organic antireflection film was formed. Next, the above resist composition was spin-coated on the organic antireflection film so that the film thickness after drying was 85 nm.
After applying the resist composition, 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 the ArF excimer stepper for immersion exposure [XT: 1900 Gi; manufactured by ASML, NA = 1.35, 3/4 Annular XY deflection] on the wafer on which the resist composition film is formed in this manner, the exposure amount is stepwise. The line and space pattern was subjected to immersion exposure.
After the exposure, post exposure bake (PEB) is performed on the hot plate at a temperature described in the “PEB” column of Table 1 for 60 seconds, and further with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 60 seconds. Paddle development was performed.

  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.

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 5 nm or less. did.
These results are shown in Table 2. The numerical value in the parenthesis indicates the touch width (nm) of the unevenness on the side wall of the resist pattern.

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

Claims (6)

A salt represented by the formula (I).

[In Formula (I), Q ¹ and Q ² each independently represents a fluorine atom or a C _1-6 perfluoroalkyl group.
n represents an integer of 2 to 3.
Z ⁺ represents a cation represented by the formula (b2-1), a cation represented by the formula (b2-2), or a cation represented by the formula (b2-3). ]

[In formula (b2-1), R ^{b4 to} R ^b6 each independently represents a C _1-30 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group. A hydrogen atom contained in the aromatic hydrocarbon group is substituted with a halogen atom, a hydroxy group, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _1-12 alkoxy group It may be. However, at least one of R ^{b4 to} R ^b6 represents a C _6-18 aromatic hydrocarbon group. ]

[In Formula (b2-2), R ^b7 and R ^b8 each independently represent a hydroxy group, a C _1-12 aliphatic hydrocarbon group, or a C _1-12 alkoxy group.
m2 and n2 each independently represent an integer of 0 to 5. When m2 is 2 or more, the plurality of R ^b7 may be the same or different, and when n2 is 2 or more, the plurality of R ^b8 may be the same or different. ]

[In Formula (b2-3), R ^b9 and R ^b10 each independently represent a C _1-36 aliphatic hydrocarbon group or a C _3-36 saturated cyclic hydrocarbon group, or form a ring with S; —CH ₂ — contained in the ring may be replaced by —O— or —S—.
R ^b11 represents a hydrogen atom, a C _1-36 aliphatic hydrocarbon group, or a C _3-36 saturated cyclic hydrocarbon group.
R ^b12 represents a C _6-18 aromatic hydrocarbon group, and the hydrogen atom contained in the aromatic hydrocarbon group is a C _1-12 aliphatic hydrocarbon group, a C _1-12 alkoxy group, a nitro group, C _It may be substituted with a _3-18 saturated cyclic hydrocarbon group or an alkylcarbonyloxy group. ] The salt according to claim 1 , wherein n is 2 . The acid generator containing the salt of Claim 1 or 2 . A resin comprising the acid generator according to claim 3 and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, and is soluble in an alkaline aqueous solution by the action of an acid. A resist composition. The resist composition according to claim 4 containing a basic compound. (1) The process of apply | coating the resist composition of Claim 4 or 5 on a board | substrate,
(2) The process of drying the composition after application | coating and forming 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: