JP5677673B2 - Salt for acid generator, 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, and more specifically, a salt suitably used for an acid generator, a chemically amplified resist composition containing the salt as an acid generator, and The present invention relates to a method for manufacturing 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 triphenylsulfonium 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate as a salt for an acid generator.

JP 2007-224008 A

  A resist composition containing a conventional acid generator may not always satisfy the line edge roughness of the resulting pattern.

［式（Ｉ）中、
Ｗは、炭素数３〜３６の飽和炭化水素環を表し、該飽和炭化水素環に含まれる−ＣＨ_２−は、−Ｏ−、−ＳＯ_２−又は−ＣＯ−で置き換わっていてもよい。
Ｌ^１は、単結合又は２価の炭素数１〜１７の飽和炭化水素基を表し、該２価の飽和炭化水素基に含まれる水素原子はフッ素原子で置換されていてもよく、該２価の飽和炭化水素基に含まれる−ＣＨ_２−は、−Ｏ−又は−ＣＯ−で置き換わっていてもよい。
Ｑ¹及びＱ²は、それぞれ独立に、フッ素原子又は炭素数１〜６のペルフルオロアルキル基を表す。
Ｚ^＋は、有機カチオンを表す。］
〔２〕式（ＩＩ）で表される〔１〕記載の塩。

［式（ＩＩ）中、Ｌ^１、Ｑ¹、Ｑ²及びＺ^＋は、上記と同じ意味を表す。］ The present invention includes the following inventions.
[1] A salt represented by the formula (I).

[In the formula (I),
W represents a saturated hydrocarbon ring having 3 to 36 carbon atoms, and —CH ₂ — contained in the saturated hydrocarbon ring may be replaced by —O—, —SO ₂ — or —CO—.
L ¹ represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, a hydrogen atom contained in the divalent saturated hydrocarbon group may be substituted with a fluorine atom, and the divalent —CH ₂ — contained in the saturated hydrocarbon group may be replaced by —O— or —CO—.
Q ¹ and Q ² each independently represents a fluorine atom or a C 1-6 perfluoroalkyl group.
Z ⁺ represents an organic cation. ]
[2] The salt according to [1] represented by the formula (II).

[In Formula (II), L ¹ , Q ¹ , Q ² and Z ⁺ represent the same meaning as described above. ]

[3] An acid generator containing the salt described in [1] or [2] above.
[4] The acid generator according to the above [3] and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, Resist composition which resin is resin which can be dissolved with alkaline aqueous solution.
[5] The resist composition according to [4], which contains a basic compound.

[6] (1) A step of applying the resist composition according to [4] or [5] 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 method for producing a resist pattern, comprising a step of developing the heated composition layer using a developing device.

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

ここで、芳香族炭化水素としては、ベンゼン、ナフタレン、アントラセン、ｐ−トルエン、ｐ−ｔｅｒｔ−ブチルベンゼン、ｐ−アダマンチルベンゼン、１，２−ジメチルベンゼン、１，３−ジメチルベンゼン、１，４−ジメチルベンゼン、（１−メチルエチル）ベンゼン、１，３，５−トリメチルベンゼン、ジフェニル、フェナントレン、２，６−ジエチルベンゼン、２−メチル−６−エチルベンゼン等が挙げられる。 <salt>
The salt of the present invention (hereinafter sometimes referred to as “salt (I)”) is represented by the formula (I).
In the formula (I), the saturated hydrocarbon ring may be monocyclic or polycyclic. For example, a monocyclic saturated hydrocarbon ring such as cycloalkane (for example, cycloalkane such as cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, and cyclooctane) can be used. Examples thereof include polycyclic saturated hydrocarbon rings such as a ring obtained by hydrogenating a condensed aromatic hydrocarbon (for example, hydronaphthalene) and a bridged cyclic hydrocarbon (for example, adamantane, norbornane, methylnorbornane). Further, a ring in which a bridged ring (for example, norbornane) and a single ring (for example, cycloheptane, cyclohexane) or a polycycle (for example, decahydronaphthalene) is condensed or a ring in which the bridged rings are condensed; Combined rings (methylcyclohexane, dimethylcyclohexane, methylnorbornane) and the like can be mentioned.

Here, examples of the aromatic hydrocarbon include benzene, naphthalene, anthracene, p-toluene, p-tert-butylbenzene, p-adamantylbenzene, 1,2-dimethylbenzene, 1,3-dimethylbenzene, 1,4- Examples thereof include dimethylbenzene, (1-methylethyl) benzene, 1,3,5-trimethylbenzene, diphenyl, phenanthrene, 2,6-diethylbenzene, 2-methyl-6-ethylbenzene and the like.

Examples of the group in which —CH ₂ — contained in the saturated hydrocarbon ring is replaced by —O—, —SO ₂ — or —CO— include the following groups.

The saturated hydrocarbon ring may have a substituent. Examples of the substituent include a hydroxyl group, an alicyclic hydrocarbon group having 3 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aromatic hydrocarbon group having 6 to 10 carbon atoms.
Examples of the alicyclic hydrocarbon group having 3 to 12 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, an adamantyl group, and a norbornyl group.
Examples of the 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, an n-hexoxy group, and an octyloxy group. , 2-ethylhexyloxy group and the like.
Examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenyl group, a naphthyl group, and an anthryl group.

Examples of the divalent saturated hydrocarbon group include a linear alkanediyl group, a branched alkanediyl group, a monocyclic or polycyclic saturated hydrocarbon group, and two or more of these groups are combined. It may be a thing.
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 alkanediyl groups such as 17-diyl group, methylidene group, ethylidene group, propylidene group, 2-propylidene group;
An alkyl group (particularly an alkyl group having 1 to 4 carbon atoms, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, etc.) is added to the linear alkanediyl. Those having a side 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-propylene group Branched alkanediyl such as butylene group, 2-methyl-1,4-butylene group;
A monocyclic saturated hydrocarbon group which is a cycloalkylene group such as a 1,3-cyclobutylene group, a 1,3-cyclopentylene group, a 1,4-cyclohexylene group, a 1,5-cyclooctylene group;
Examples thereof include polycyclic saturated hydrocarbon groups such as 1,4-norbornylene group, 2,5-norbornylene group, 1,5-adamantylene group and 2,6-adamantylene group.

Examples of the group in which —CH ₂ — contained in the saturated hydrocarbon group is replaced by —O— or —CO— include formula (b1-1) to formula (b1-6).
In addition, the formula (b1-1) to the formula (b1-6) are described in accordance with the formula (I) on the left and right sides, combined with C (Q ¹ ) (Q ² )-on the left side, and on the right side. Bonded with ring W. The same applies to specific examples of the following formulas (b1-1) to (b1-6).

式（ｂ１−１）〜式（ｂ１−６）中、
Ｌ^b2は、単結合又は炭素数１〜１５の飽和炭化水素基を表す。
Ｌ^b3は、単結合又は炭素数１〜１２の飽和炭化水素基を表す。
Ｌ^b4は、炭素数１〜１３の飽和炭化水素基を表す。但しＬ^b3及びＬ^b4の炭素数上限は１３である。
Ｌ^b5は、炭素数１〜１５の飽和炭化水素基を表す。
Ｌ^b6及びＬ^b7は、それぞれ独立に、炭素数１〜１５の飽和炭化水素基を表す。但しＬ^b6及びＬ^b7の炭素数上限は１６である。
Ｌ^b8は、炭素数１〜１４の飽和炭化水素基を表す。
Ｌ^b9は、炭素数１〜１１の飽和炭化水素基を表す。
Ｌ^b10は、炭素数１〜１１の飽和炭化水素基を表す。但しＬ^ｂ９及びＬ^ｂ１０の炭素数上限は１２である。

In formula (b1-1) to formula (b1-6),
L ^b2 represents a single bond or a saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^b3 represents a single bond or a saturated hydrocarbon group having 1 to 12 carbon atoms.
L ^b4 represents a saturated hydrocarbon group having 1 to 13 carbon atoms. However, the upper limit of the carbon number of L ^b3 and L ^b4 is 13.
L ^b5 represents a saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^b6 and L ^b7 each independently represent a saturated hydrocarbon group having 1 to 15 carbon atoms. However, the upper limit of the carbon number of L ^b6 and L ^b7 is 16.
L ^b8 represents a saturated hydrocarbon group having 1 to 14 carbon atoms.
L ^b9 represents a saturated hydrocarbon group having 1 to 11 carbon atoms.
L ^b10 represents a saturated hydrocarbon group having 1 to 11 carbon atoms. However, the upper limit of the carbon number of L ^b9 and L ^b10 is 12.

The saturated hydrocarbon group for L ^{b2 to} L ^b9 is preferably an alkanediyl group, and the saturated hydrocarbon group for L ^b10 is preferably an alkanediyl group and an alicyclic hydrocarbon group having 3 to 10 carbon atoms, A group, a cyclohexyl group and an adamantyl group are more preferred.

Examples of the divalent group represented by the formula (b1-1) include the following.

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

Examples of the divalent group represented by the formula (b1-3) include the following.

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

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

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

  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.

  In the present specification, unless otherwise specified, any of the chemical structural formulas having the same substituents may be applied to the specific substituents described above or described later while appropriately selecting the number of carbon atoms. it can. Those which can take any of linear, branched or cyclic are included unless otherwise specified, and in the same group, linear, branched and / or cyclic partial structures are mixed. It may be. When stereoisomers exist, all of those stereoisomers are included. Furthermore, each substituent can be a monovalent or divalent or higher substituent depending on the bonding site and the bonding mode.

W is preferably a ring represented by the formula (a1-1) to the formula (a1-3). Note that bond to L ¹ may be any position.

L ¹ is preferably any of formula (b1-1) to formula (b1-4), more preferably formula (b1-1) or formula (b1-2). Among these, a divalent group represented by the formula (b1-1) is preferable, and a divalent group represented by the formula (b1-1) in which L ^b2 is a single bond or —CH ₂ — is more preferable.
Note that a hydrogen atom contained in L ¹ may be substituted with a fluorine atom.
Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.

Examples of the salt (I) include the following salts.

Especially, what has a bivalent group represented by Formula (b1-1) and Formula (b1-2) is preferable, for example, the following salts are mentioned.

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 (b2-1) to (b2-4).

In these formulas (b2-1) to (b2-4),
R ^{b4 to} R ^b6 each independently represents an aliphatic hydrocarbon group having 1 to 30 carbon atoms, a saturated hydrocarbon group having 3 to 36 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms. The aliphatic hydrocarbon group may be substituted with a hydroxy group, an alkoxy group having 1 to 12 carbon atoms or an aromatic hydrocarbon group having 6 to 18 carbon atoms, and the saturated hydrocarbon group includes a halogen atom, a carbon atom The aromatic hydrocarbon group may be substituted with an acyl group of 2 to 4 or a glycidyloxy group, and the aromatic hydrocarbon group is a halogen atom, a hydroxy group, an aliphatic hydrocarbon group of 1 to 36 carbon atoms, or 3 to 36 carbon atoms. May be substituted with a saturated hydrocarbon group or an alkoxy group having 1 to 12 carbon atoms.

R ^b7 and R ^b8 each independently represent a hydroxy group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
m2 and n2 each independently represent an integer of 0 to 5.

R ^b9 and R ^b10 each independently represent an aliphatic hydrocarbon group having 1 to 36 carbon atoms or a saturated hydrocarbon group having 3 to 36 carbon atoms.
R ^b11 represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 36 carbon atoms, a saturated hydrocarbon group having 3 to 36 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms.
The aliphatic hydrocarbon group of R ^{b9 to} R ^b11 preferably has 1 to 12 carbon atoms, and the saturated hydrocarbon group preferably has 3 to 36 carbon atoms, more preferably 4 to 12 carbon atoms.
R ^b12 represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a saturated hydrocarbon group having 3 to 18 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms. The aromatic hydrocarbon group may be substituted with an aliphatic hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a saturated hydrocarbon group having 3 to 18 carbon atoms, or an alkylcarbonyloxy group. Good.
R ^b9 and R ^b10 may be bonded to each other together with the sulfur atom to which they are bonded to form a 3- to 12-membered ring (preferably a 3- to 7-membered ring), and R ^b11 and R ^b12 are , And -CH-CO- to which they are bonded may form a 3- to 12-membered ring (preferably a 3- to 7-membered ring).

R ^{b13 to} R ^b18 each independently represent a hydroxy group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
L ^b11 represents -S- or -O-.
o2, p2, s2, and t2 each independently represents an integer of 0 to 5.
q2 and r2 each independently represents an integer of 0 to 4.
u2 represents 0 or 1.
When any one of o2 to t2 is 2, any one of the plurality of R ^{b13 to} R ^b18 is the same as or different from each other.

Examples of the aliphatic hydrocarbon group include methyl group, ethyl group, n-propyl group, 1-methylethyl group (isopropyl group), n-butyl group, 1,1-dimethylethyl group (tert-butyl group), 2, 2-dimethylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, 1-ethylpropyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, n-hexyl group, 1-propylbutyl group, pentyl group, 1-methylpentyl group, 1,4-dimethylhexyl group, heptyl group, 1-methylheptyl group, octyl group, Examples thereof include alkyl groups such as nonyl group, decyl group, undecyl group, and dodecyl group.
Examples of the alkoxy group include methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, decyloxy group and dodecyloxy group.
Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
Examples of the saturated hydrocarbon include monocyclic cycloalkylene groups such as 1,3-cyclobutylene group, 1,3-cyclopentylene group, 1,4-cyclohexylene group, and 1,5-cyclooctylene group. Alicyclic hydrocarbon groups; polycyclic alicyclic hydrocarbon groups such as 1,4-norbornylene group, 2,5-norbornylene group, 1,5-adamantylene group, 2,6-adamantylene group, etc. Can be mentioned.

  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.

In the formulas (b2-1) to (b2-4), preferred aliphatic hydrocarbon groups are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl. Group, pentyl group, hexyl group, octyl group and 2-ethylhexyl group.
Preferred saturated hydrocarbon groups are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclodecyl, 2-alkyl-2-adamantyl, 1- (1-adamantyl) -1-alkyl and isobornyl. It is a 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 ring formed by R ^b9 and R ^b10 include a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathian-4-ium ring.
^Examples of the ring formed by R ^b11 and R ^b12 include an oxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, and an oxoadamantane ring.

  Among the cations (b2-1) to (b2-4), the cation (b2-1) is preferable, the cation represented by the formula (b2-1-1) is more preferable, and the triphenylsulfonium cation (formula (b2) In (1-1), v2 = w2 = x2 = 0) is more preferable.

式（ｂ２−１−１）中、
Ｒ^b19〜Ｒ^b21は、それぞれ独立に、ハロゲン原子（より好ましくはフッ素原子）、ヒドロキシ基、炭素数１〜３６の脂肪族炭化水素基、炭素数３〜３６の飽和炭化水素基又は炭素数１〜１２のアルコキシ基を表す。
脂肪族炭化水素基は、好ましくは炭素数１〜１２であり、飽和炭化水素基は、好ましくは炭素数４〜３６である。
前記脂肪族炭化水素基は、ヒドロキシ基、炭素数１〜１２のアルコキシ基又は炭素数６〜１８の芳香族炭化水素基で置換されていてもよい。
前記飽和炭化水素基は、ハロゲン原子、炭素数２〜４のアシル基又はグリシジルオキシ基で置換されていてもよい。
ｖ２〜ｘ２は、それぞれ独立に０〜５の整数（好ましくは０又は１）を表す。ｖ２〜ｘ２のいずれかが２以上のとき、それぞれ、複数のＲ^b19〜Ｒ^b21のいずれかは、互いに同一又は相異なる。
なかでも、Ｒ^b19〜Ｒ^b21は、それぞれ独立に、好ましくは、ハロゲン原子（より好ましくはフッ素原子）、ヒドロキシ基、炭素数１〜１２のアルキル基又は炭素数１〜１２のアルコキシ基である。

In formula (b2-1-1),
R ^{b19 to} R ^b21 each independently represent a halogen atom (more preferably a fluorine atom), a hydroxy group, an aliphatic hydrocarbon group having 1 to 36 carbon atoms, a saturated hydrocarbon group having 3 to 36 carbon atoms, or 1 carbon atom. Represents an alkoxy group of ˜12.
The aliphatic hydrocarbon group preferably has 1 to 12 carbon atoms, and the saturated hydrocarbon group preferably has 4 to 36 carbon atoms.
The aliphatic hydrocarbon group may be substituted with a hydroxy group, an alkoxy group having 1 to 12 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms.
The saturated hydrocarbon group may be substituted with a halogen atom, an acyl group having 2 to 4 carbon atoms, or a glycidyloxy group.
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, each of the plurality of R ^{b19 to} R ^b21 is the same as or different from each other.
Among these, R ^{b19 to} R ^b21 are preferably each independently a halogen atom (more preferably a fluorine atom), a hydroxy group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

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

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

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

Specific examples of the cation (b2-4) include the following.

  Salt (I) is a combination of the anions and organic cations described above. Although the above-mentioned anion and cation can be combined arbitrarily, the salt represented below is preferable.

ここで用いる溶媒としては、無水酢酸等が挙げられる。
触媒としては、硫酸等が挙げられる。
式（ｂ２−ｂ）で表される塩としては、トリフェニルスルホニウム ４−オキソ−１−アダマンチルオキシカルボニルジフルオロメタンスルホナートが好ましい。 The salt (I) can be obtained, for example, by reacting the compound represented by the formula (b2-a) with the salt represented by the formula (b2-b) in the presence of an acid catalyst. it can.

Examples of the solvent used here include acetic anhydride.
Examples of the catalyst include sulfuric acid.
As the salt represented by the formula (b2-b), triphenylsulfonium 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate is preferable.

<Acid generator>
The acid generator of the present invention contains a salt (I). When the salt (I) is used as an acid generator, it may be used alone or in combination. The acid generator of the present invention further comprises a known salt other than the salt (I), a salt comprising a cation and a known anion contained in the salt (I), and an anion and a known cation contained in the salt (I). The salt which consists of, etc. may be included.

<Resist composition>
The resist composition of the present invention comprises an acid generator containing salt (I) and a resin.
The content of the acid generator containing the salt (I) is preferably 1 part by mass or more (more preferably 3 parts by mass or more), preferably 40 parts by mass or less (more preferably) with respect to 100 parts by mass of the resin described later. Is 35 parts by mass or less).

<Resin (hereinafter sometimes referred to as “resin (A)”)>
Resin (A) is a resin that becomes alkali-soluble by the action of an acid. A resin that becomes alkali-soluble by the action of an acid 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 alkali-soluble by the action of acid. 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 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 (1) in which —O— is bonded to a tertiary carbon atom (excluding a bridgehead carbon atom of a bridged cyclic hydrocarbon group) (ie, An ester bond having a tertiary alcohol residue). Hereinafter, the group represented by the formula (1) may be referred to as “acid-labile group (1)”.

式（１）中、Ｒ^a1〜Ｒ^a3は、それぞれ独立に、脂肪族炭化水素基又は飽和炭化水素基を表すか或いはＲ^a1及びＲ^a2は互いに結合して環を形成していてもよい。＊は結合手を表す（以下同じ）。

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

In the formula (1), the saturated hydrocarbon group preferably has 3 to 20 carbon atoms, more preferably 3 to 12 carbon atoms.
Examples of the ring formed by combining R ^a1 and R ^a2 with each other include a saturated hydrocarbon group and an aromatic hydrocarbon group. Such a ring preferably has 3 to 20 carbon atoms, more preferably 3 to 12 carbon atoms.

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 the formula (1), 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
Among the (meth) acrylic monomers having the acid-labile group (1), those having a saturated hydrocarbon group having 5 to 20 carbon atoms are preferable. If a resin obtained by polymerizing the monomer (a1) having a bulky structure such as a saturated hydrocarbon group is used, the resolution of the resist can be improved.

  Among (meth) acrylic monomers having an acid labile group (1) and a saturated hydrocarbon group, an acid labile group represented by formula (a1-1) or formula (a1-2) The monomer which has is preferable. These may be used alone or in combination of two or more.

式（ａ１−１）及び式（ａ１−２）中、
Ｌ^a1及びＬ^a2は、それぞれ独立に、−Ｏ−又は−Ｏ−（ＣＨ₂）_k1−ＣＯ−Ｏ−を表し、ｋ１は１〜７の整数を表す。但しＬ^a1及びＬ^a2で列挙した−Ｏ−等は、それぞれ、左側で式（ａ１−１）及び式（ａ１−２）の−ＣＯ−と結合し、右側でアダマンチル基又はシクロへキシル基と結合することを意味する。
Ｒ^a4及びＲ^a5は、それぞれ独立に、水素原子又はメチル基を表す。
Ｒ^a6及びＲ^a7は、それぞれ独立に、炭素数１〜８の脂肪族炭化水素基又は炭素数３〜１０の飽和炭化水素基を表す。
ｍ１は０〜１４の整数を表す。
ｎ１は０〜１０の整数を表す。
ｎ２は０又は１の整数を表す。

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 an integer of 1 to 7. However, —O— and the like enumerated for L ^a1 and L ^a2 are respectively bonded to —CO— of the formula (a1-1) and the formula (a1-2) on the left side, and to an adamantyl group or cyclohexyl group on the right side. Means to join.
R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group.
R ^a6 and R ^a7 each independently represent an aliphatic hydrocarbon group having 1 to 8 carbon atoms or a saturated hydrocarbon group having 3 to 10 carbon atoms.
m1 represents the integer of 0-14.
n1 represents an integer of 0 to 10.
n2 represents an integer of 0 or 1.

In the formula (a1-1) and the formula (a1-2), L ^a1 and L ^a2 are preferably, -O- or _{-O- (CH 2) f1 -CO-} O- and is (wherein f1 is 1 to 4), and more preferably -O-.
R ^a4 and R ^a5 are preferably methyl groups.
The aliphatic hydrocarbon group represented by R ^a6 and R ^a7 preferably has 6 or less carbon atoms. The saturated hydrocarbon group preferably has 8 or less carbon atoms, more preferably 6 or less carbon atoms.
m1 is preferably an integer of 0 to 3, more preferably 0 or 1.
n1 is preferably an integer of 0 to 3, more preferably 0 or 1.
k1 is preferably an integer of 1 to 4, more preferably 1.

  As a monomer (a1-1) which has an adamantyl group, the following are mentioned, for example. Among them, 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.

  As a monomer (a1-2) which has a cyclohexyl group, the following are mentioned, for example. 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 (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.

式（ａ１−３）中、
Ｒ^a9は、水素原子、置換基（例えば、ヒドロキシ基）を有していてもよい炭素数１〜３の脂肪族炭化水素基、カルボキシ基、シアノ基又は基−ＣＯＯＲ^a13（Ｒ^a13は、炭素数１〜８の脂肪族炭化水素基又は炭素数３〜８の飽和炭化水素基を表し、前記脂肪族炭化水素基及び前記飽和炭化水素基の水素原子はヒドロキシ基で置換されていてもよく、前記脂肪族炭化水素基及び前記飽和炭化水素基の−ＣＨ_２−は−Ｏ−又は−ＣＯ−で置き換わっていてもよい）を表す。
Ｒ^a10〜Ｒ^a12は、それぞれ独立に、炭素数１〜１２の脂肪族炭化水素基又は炭素数３〜１２の飽和炭化水素基を表すか、或いはＲ^a10及びＲ^a11は互いに結合して環を形成していてもよく、前記脂肪族炭化水素基及び前記飽和炭化水素基の水素原子はヒドロキシ基等で置換されていてもよく、前記脂肪族炭化水素基及び前記飽和炭化水素基の−ＣＨ_２−は−Ｏ−又は−ＣＯ−で置き換わっていてもよい。

In formula (a1-3),
R ^a9 represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 3 carbon atoms which may have a substituent (for example, a hydroxy group), a carboxy group, a cyano group, or a group —COOR ^a13 (R ^a13 represents carbon Represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms or a saturated hydrocarbon group having 3 to 8 carbon atoms, and the hydrogen atom of the aliphatic hydrocarbon group and the saturated hydrocarbon group may be substituted with a hydroxy group, In the aliphatic hydrocarbon group and the saturated hydrocarbon group, —CH ₂ — may be replaced by —O— or —CO—.
R ^{a10 to} R ^a12 each independently represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated hydrocarbon group having 3 to 12 carbon atoms, or R ^a10 and R ^a11 are bonded to each other to form a ring. The hydrogen atom of the aliphatic hydrocarbon group and the saturated hydrocarbon group may be substituted with a hydroxy group or the like, and —CH _{2 of the} aliphatic hydrocarbon group and the saturated hydrocarbon group may be formed. -May be replaced by -O- or -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 ring formed by R ^a10 , R ^a11 and the carbon to which they are bonded include saturated hydrocarbon groups. Specific examples 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 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炭素数１〜６のアルキル基を表す。
Ｒ¹¹は、それぞれ独立に、ハロゲン原子、ヒドロキシ基、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基、炭素数２〜４のアシル基、炭素数２〜４のアシルオキシ基、アクリロイル基又はメタクリロイル基を表す。
ｌａは０〜４の整数を表す。ｌａが２以上の整数である場合、複数のＲ¹¹は同一又は相異なる。
Ｒ¹²及びＲ¹³はそれぞれ独立に、水素原子又は炭素数１〜１２の炭化水素基を表す。
Ｘ^ａ２は、単結合又は置換基を有していてもよい２価の炭素数１〜１７の飽和炭化水素基を表し、該飽和炭化水素基に含まれる−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、水素原子又は炭素数１〜６のアルキル基を表す。
Ｙ^ａ３は、炭素数１〜１２の脂肪族炭化水素基、炭素数３〜１８の飽和炭化水素基又は炭素数６〜１８の芳香族炭化水素基であり、該脂肪族炭化水素基、飽和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 an acid labile group and a carbon-carbon double bond include a monomer (a1-4) represented by the formula (a1-4).

[In the formula (a1-4),
R ¹⁰ represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
R ¹¹ each independently represents a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 4 carbon atoms, an acyloxy group having 2 to 4 carbon atoms, Represents an acryloyl group or a methacryloyl group.
la represents an integer of 0 to 4. When la is an integer of 2 or more, the plurality of R ¹¹ are the same or different.
R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms.
X ^a2 represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms which may have a substituent, and —CH ₂ — contained in the saturated hydrocarbon group is —CO—, — O—, —S—, —SO ₂ — or —N (R ^c ) — may be substituted. R ^c represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Y ^a3 is an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a saturated hydrocarbon group having 3 to 18 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms, and the aliphatic hydrocarbon group, saturated hydrocarbon group The hydrogen 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 acyl group include an acetyl group, a propionyl group, and a butyryl group.
Examples of the acyloxy group include acetyloxy, propionyloxy, butyryloxy and the like.
Examples of the hydrocarbon group include an aliphatic hydrocarbon group, a saturated hydrocarbon group, and an aromatic hydrocarbon group.

In formula (a1-4), the alkyl group of R ¹⁰ and R ¹¹ preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably a methyl group.
As the alkoxy group for R ¹¹ , C 1 or 2 is more preferable, and a methoxy group is particularly preferable.
Examples of the hydrocarbon group for R ¹² and R ¹³ include isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, cyclohexyl group, adamantyl group, A 2-alkyl-2-adamantyl group, a 1- (1-adamantyl) -1-alkyl group, an isobornyl group, and the like are preferable.
Examples of the group that may be substituted with the groups X ^a2 and Y ^a3 include a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an acyl group having 2 to 4 carbon atoms. And an acyloxy group having 2 to 4 carbon atoms. Of these, a hydroxy group is preferable.

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%.

Furthermore, a monomer that derives another structural unit having an acid labile group (1) and a carbon-carbon double bond in the molecule may be used.
Examples of such other acid labile monomers include the following monomers.

  When the resin (A) has a structural unit derived from another acid labile monomer, the content is preferably 10 to 95 mol% with respect to the total structural unit (100 mol%) of the resin (A). More preferably, it is 15-90 mol%, More preferably, it is 20-85 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 converted to 15 mol per 100 mol% of the monomer (a1) having an acid labile group. It is preferable to make it mol% or more. 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 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炭素数１〜６のアルキル基を表す。
Ｒ^９は、ハロゲン原子、ヒドロキシ基、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基、炭素数２〜４のアシル基、炭素数２〜４のアシルオキシ基、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は同一又は相異なる。］

[In the formula (a2-0),
R ⁸ represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
R ⁹ is a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 4 carbon atoms, an acyloxy group having 2 to 4 carbon atoms, an acryloyl group, or methacryloyl. Represents a group.
ma represents an integer of 0 to 4. When ma is an integer of 2 or more, the plurality of R ⁹ are the same or different. ]

As the alkyl group for R ^8, an alkyl group having 1 to 4 carbon atoms is preferable, an alkyl group having 1 or 2 carbon atoms is more preferable, and a methyl group is particularly preferable.
Moreover, as an alkoxy group, a C1-C4 alkoxy group is preferable, a C1-C2 alkoxy group is more preferable, and a methoxy group is especially preferable.
ma is preferably 0 to 2, more preferably 0 or 1, and particularly preferably 0.

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).

式（ａ２−１）中、
Ｌ^a3は、−Ｏ−又は−Ｏ−（ＣＨ₂）_k2−ＣＯ−Ｏ−を表し、
ｋ２は１〜７の整数を表す。
Ｒ^a14は、水素原子又はメチル基を表す。
Ｒ^a15及びＲ^a16は、それぞれ独立に、水素原子、メチル基又はヒドロキシ基を表す。
ｏ１は、０〜１０の整数を表す。

In formula (a2-1),
L ^a3 represents —O— or —O— (CH ₂ ) _k2 —CO—O—,
k2 represents an integer of 1 to 7.
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.

In the formula (a2-1), L ^a3 is preferably, -O -, - O- (CH 2) f1 -CO-O- and is (wherein f1 is an integer from 1 to 4), more preferably Is —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.

  As an acid stable monomer (a2-1) which has a hydroxyadamantyl group, the following are mentioned, for example. Among them, 3-hydroxy-1-adamantyl (meth) acrylate, 3,5-dihydroxy-1-adamantyl (meth) acrylate, and 1- (3,5-dihydroxy-1-adamantyloxycarbonyl) methyl (meth) acrylate are Preferably, 3-hydroxy-1-adamantyl (meth) acrylate and 3,5-dihydroxy-1-adamantyl (meth) acrylate are more preferable, 3-hydroxy-1-adamantyl methacrylate and 3,5-dihydroxy-1-adamantyl methacrylate Is more preferable.

  The content of the structural unit derived from the monomer represented by the formula (a2-1) in the resin is usually from 3 to 45 mol%, preferably from 5 to 40 mol%, more preferably in all units of the resin. Is 5 to 35 mol%.

<Acid-stable monomer having a lactone ring (a3)>
The lactone ring possessed by the acid stable monomer (a3) may be, for example, a monocyclic ring such as a β-propiolactone ring, a γ-butyrolactone ring, or a δ-valerolactone ring, or a monocyclic lactone ring and another ring. 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.

式（ａ３−１）〜式（ａ３−３）中、
Ｌ^a4〜Ｌ^a6は、それぞれ独立に、−Ｏ−又は−Ｏ−（ＣＨ₂）_k3−ＣＯ−Ｏ−を表す。
ｋ３は１〜７の整数を表す。
Ｒ^a18〜Ｒ^a20は、それぞれ独立に、水素原子又はメチル基を表す。
Ｒ^a21は、炭素数１〜４の脂肪族炭化水素基を表す。
ｐ１は０〜５の整数を表す。
Ｒ^a22及びＲ^a23は、それぞれ独立に、カルボキシ基、シアノ基又は炭素数１〜４の脂肪族炭化水素基を表す。
ｑ１及びｒ１は、それぞれ独立に０〜３の整数を表す。ｐ１、ｑ１又はｒ１が２以上のとき、それぞれ、複数のＲ^a21、Ｒ^a22又はＲ^a23は、互いに同一又は相異なる。

In formula (a3-1) to formula (a3-3),
L ^{a4 to} L ^a6 each independently represent —O— or —O— (CH ₂ ) _k3 —CO—O—.
k3 represents an integer of 1 to 7.
R ^{a18 to} R ^a20 each independently represents a hydrogen atom or a methyl group.
R ^a21 represents an aliphatic hydrocarbon group having 1 to 4 carbon atoms.
p1 represents an integer of 0 to 5.
R ^a22 and R ^a23 each independently represent a carboxy group, a cyano group, or an aliphatic hydrocarbon group having 1 to 4 carbon atoms.
q1 and r1 each independently represents 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 are the same or different from each other.

In the formula (a3-1) to the formula (a3-3), 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— (wherein d1 is an integer of 1 to 4), more preferably -O-. However, —O— and the like enumerated in L ^{a4 to} L ^a6 mean that they are bonded to —CO— of the formula (a3-1) to the formula (a3-3) on the left side and to the lactone ring on the right side. To do.
R ^{a18 to} R ^a21 are preferably methyl groups.
R ^a22 and R ^a23 are each independently preferably a carboxy group, a cyano group or a methyl group.
p1 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.

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

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

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.

  Content of the structural unit derived from the monomer represented by Formula (a3-1), Formula (a3-2) or Formula (a3-3) in the resin is usually 5 to 70 mol% in all units of the resin. Yes, preferably 10 to 65 mol%, more preferably 10 to 60 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.

式（ａ４−３）中、
Ｒ^a25及びＲ^a26は、それぞれ独立に、水素原子、置換基（例えば、ヒドロキシ基）を有していてもよい炭素数１〜３の脂肪族炭化水素基、シアノ基、カルボキシ基又は基−ＣＯＯＲ^a27を表すか、或いはＲ^a25及びＲ^a26は互いに結合して−ＣＯ−Ｏ−ＣＯ−を形成し、
Ｒ^a27は、炭素数１〜３６の脂肪族炭化水素基又は炭素数３〜３６の飽和炭化水素基を表し、脂肪族炭化水素基及び飽和炭化水素基の−ＣＨ_２−は、−Ｏ−又は−ＣＯ−で置き換わっていてもよい。但し−ＣＯＯＲ^a27が酸不安定基となるものは除く（即ちＲ^a27は、３級炭素原子が−Ｏ−と結合するものを含まない）。

In formula (a4-3),
R ^a25 and R ^a26 each independently represent a hydrogen atom, an aliphatic hydrocarbon group having 1 to 3 carbon atoms which may have a substituent (for example, a hydroxy group), a cyano group, a carboxy group, or a group —COOR. ^{a 27} or R ^a25 and R ^a26 combine with each other to form —CO—O—CO—;
R ^a27 represents an aliphatic hydrocarbon group having 1 to 36 carbon atoms or a saturated hydrocarbon group having 3 to 36 carbon atoms, and —CH ₂ — of the aliphatic hydrocarbon group and the saturated hydrocarbon group is —O— or It may be replaced by -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 aliphatic hydrocarbon group for R ^a27 preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms. The saturated hydrocarbon group preferably has 4 to 36 carbon atoms, more preferably 4 to 12 carbon atoms.
^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, 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 (a4-1), Formula (a4-2), or Formula (a4-3) 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 (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 content of resin (A) is 80 mass% or more in solid content of a composition. Here, the “solid content in the composition” means the total of the resist composition components excluding the solvent (E) described later. The solid content in the composition and the content of the resin (A) relative thereto can be measured by a known analysis 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 suitably 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, amine or ammonium salt). 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).

ここで、Ａｒ^c1は、芳香族炭化水素基を表す。
Ｒ^c5及びＲ^c6は、それぞれ独立に、水素原子、脂肪族炭化水素基（好ましくはアルキル基又はシクロアルキル基）、飽和炭化水素基又は芳香族炭化水素基を表す。
Ｒ^c7は、脂肪族炭化水素基（好ましくはアルキル基又はシクロアルキル基）、アルコキシ基、飽和炭化水素基又は芳香族炭化水素基を表す。
但し脂肪族炭化水素基、アルコキシ基、飽和炭化水素基及び芳香族炭化水素基の水素原子は、ヒドロキシ基、アミノ基又は炭素数１〜６のアルコキシ基で置換されていてもよく、前記アミノ基は、炭素数１〜４のアルキル基で置換されていてもよい。
脂肪族炭化水素基は、好ましくは炭素数１〜６程度である。アルコキシ基は、好ましくは炭素数１〜６程度である。飽和炭化水素基は、好ましくは炭素数５〜１０程度である。芳香族炭化水素基は、好ましくは炭素数６〜１０程度である。
ｍ３は０〜３の整数を表す。ｍ３が２以上のとき、複数のＲ^c7は、互いに同一又は相異なる。

Here, Ar ^c1 represents an aromatic hydrocarbon group.
R ^c5 and R ^c6 each independently represents a hydrogen atom, an aliphatic hydrocarbon group (preferably an alkyl group or a cycloalkyl group), a saturated hydrocarbon group or an aromatic hydrocarbon group.
R ^c7 represents an aliphatic hydrocarbon group (preferably an alkyl group or a cycloalkyl group), an alkoxy group, a saturated hydrocarbon group, or an aromatic hydrocarbon group.
However, the hydrogen atom of the aliphatic hydrocarbon group, alkoxy group, saturated hydrocarbon group and aromatic hydrocarbon group may be substituted with a hydroxy group, an amino group or an alkoxy group having 1 to 6 carbon atoms, and the amino group May be substituted with an alkyl group having 1 to 4 carbon atoms.
The aliphatic hydrocarbon group preferably has about 1 to 6 carbon atoms. The alkoxy group preferably has about 1 to 6 carbon atoms. The saturated hydrocarbon group preferably has about 5 to 10 carbon atoms. The aromatic hydrocarbon group preferably has about 6 to 10 carbon atoms.
m3 represents an integer of 0 to 3. When m3 is 2 or more, the plurality of R ^c7 are the same or different from each other.

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.

ここで、
Ｒ^c8、Ｒ^c20、Ｒ^c21、Ｒ^c23〜Ｒ^c28は、それぞれ独立に、上記Ｒ^c7で説明したいずれかの基を表す。
Ｒ^c9、Ｒ^c10、Ｒ^c11〜Ｒ^c14、Ｒ^c16〜Ｒ^c19及びＲ^c22は、それぞれ独立に、Ｒ^c5及びＲ^c6で説明したいずれかの基を表す。
Ｒ^c15は、脂肪族炭化水素基、飽和炭化水素基又はアルカノイル基を表す。
ｎ３は０〜８の整数を表す。ｎ３が２以上のとき、複数のＲ^c15は、互いに同一又は相異なる。
ｏ３〜ｕ３は、それぞれ独立に０〜３の整数を表す。ｏ３〜ｕ３のいずれかが２以上であるとき、それぞれ、複数のＲ^c20〜Ｒ^c28のいずれかは互いに同一又は相異なる。
アルカノイル基としては、アセチル基、２−メチルアセチル基、２，２−ジメチルアセチル基、プロピオニル基、ブチリル基、イソブチリル基、ペンタノイル基、２，２−ジメチルプロピオニル基等が挙げられる。
Ｒ^c15の脂肪族炭化水素基は、好ましくは炭素数１〜６程度であり、飽和炭化水素基は、好ましくは炭素数３〜６程度であり、アルカノイル基は、好ましくは炭素数２〜６程度である。
Ｌ^c1及びＬ^c2は、それぞれ独立に、２価の脂肪族炭化水素基（好ましくはアルキレン基）、−ＣＯ−、−Ｃ（＝ＮＨ）−、−Ｃ（＝ＮＲ^c3）−、−Ｓ−、−Ｓ−Ｓ−又はこれらの組合せを表す。前記２価の脂肪族炭化水素基は、好ましくは炭素数１〜６程度である。
Ｒ^c3は、炭素数１〜４のアルキル基を表す。 Examples of the basic compound (C) include compounds represented by the formulas (C3) to (C11).

here,
R ^c8 , R ^c20 , R ^c21 , R ^{c23 to} R ^c28 each independently represents any of the groups described for R ^c7 above.
R ^c9 , R ^c10 , R ^{c11 to} R ^c14 , R ^{c16 to} R ^c19 and R ^c22 each independently represent any of the groups described for R ^c5 and R ^c6 .
R ^c15 represents an aliphatic hydrocarbon group, a saturated hydrocarbon group or an alkanoyl group.
n3 represents an integer of 0 to 8. When n3 is 2 or more, the plurality of R ^c15 are the same or different from each other.
o3 to u3 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 is the same as or different from each other.
Examples of the alkanoyl group include acetyl group, 2-methylacetyl group, 2,2-dimethylacetyl group, propionyl group, butyryl group, isobutyryl group, pentanoyl group, and 2,2-dimethylpropionyl group.
The aliphatic hydrocarbon group for R ^c15 preferably has about 1 to 6 carbon atoms, the saturated hydrocarbon group preferably has about 3 to 6 carbon atoms, and the alkanoyl group preferably has about 2 to 6 carbon atoms. It is.
L ^c1 and L ^c2 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 an alkyl group having 1 to 4 carbon atoms.

  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.

  As ammonium salts, tetramethylammonium hydroxide, tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, phenyltrimethylammonium hydroxide, 3- (trifluoromethyl) phenyltrimethyl Ammonium hydroxide, tetra-n-butylammonium salicylate, choline and the like can be mentioned.

<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 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. The component (F) is not particularly limited, and additives known in the resist field, for example, 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) 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 usually exposed using an exposure machine. The exposure machine may be an immersion 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 of the present invention is suitable as a resist composition for KrF excimer laser exposure, a resist composition for ArF excimer laser exposure, a resist composition for EB, or a resist composition for EUV exposure machines.

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

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

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

Example 1: Synthesis of salt B1

20.00 parts of acetic anhydride and 5.00 parts of malonic acid were charged and stirred at 23 ° C. for 30 minutes. Thereafter, 0.24 part of sulfuric acid was added to the obtained mixture, stirred at 23 ° C. for 30 minutes, and 28.19 parts of (B1-a) was added. The resulting mixture was stirred at 23 ° C. for 30 minutes, heated to 80 ° C., and further stirred for 3 hours. The mixture was cooled to 23 ° C, 100 parts of ethyl acetate was added to the resulting mixture, and the mixture was stirred at 23 ° C for 30 minutes. Thereafter, the supernatant was removed and concentrated. To the resulting concentrate, 90 parts of chloroform and 50 parts of ion-exchanged water were added, stirred at 23 ° C. for 30 minutes, and separated to recover the organic layer. This washing operation was performed 5 times. The collected organic layer was concentrated, 100 parts of acetonitrile was added to the resulting concentrate, and the mixture was stirred at 23 ° C. for 30 minutes and concentrated. To the obtained concentrate, 15 parts of acetonitrile and 100 parts of ethyl acetate were added, stirred at 23 ° C. for 3 hours, and filtered to obtain 18.90 parts of (B1) as a solid.
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 409.0

Example 2: Synthesis of salt B2

20.00 parts of acetic anhydride and 5.00 parts of malonic acid were charged and stirred at 23 ° C. for 30 minutes. Thereafter, 0.24 part of sulfuric acid was added to the obtained mixture, stirred at 23 ° C. for 30 minutes, and 30.21 parts of (B2-a) was added. The resulting mixture was stirred at 23 ° C. for 30 minutes, heated to 80 ° C., and further stirred for 3 hours. The mixture was cooled to 23 ° C, 100 parts of ethyl acetate was added to the resulting mixture, and the mixture was stirred at 23 ° C for 30 minutes. Thereafter, the supernatant was removed and concentrated. To the resulting concentrate, 100 parts of chloroform and 50 parts of ion-exchanged water were added, stirred at 23 ° C. for 30 minutes, and separated to recover the organic layer. This washing operation was performed 5 times. The collected organic layer was concentrated, 100 parts of acetonitrile was added to the resulting concentrate, and the mixture was stirred at 23 ° C. for 30 minutes and concentrated. To the obtained concentrate, 10 parts of acetonitrile and 100 parts of ethyl acetate were added, stirred at 23 ° C. for 5 hours, and filtered to obtain 19.42 parts of (B2).
MS (ESI (+) Spectrum): M ⁺ 305.1
MS (ESI (-) Spectrum): M ^- 409.0

Example 3: Synthesis of salt B3

20.00 parts of acetic anhydride and 5.00 parts of malonic acid were charged and stirred at 23 ° C. for 30 minutes. Thereafter, 0.24 part of sulfuric acid was added to the obtained mixture, stirred at 23 ° C. for 30 minutes, and 29.04 parts of (B3-a) was added. The resulting mixture was stirred at 23 ° C. for 30 minutes, heated to 80 ° C., and further stirred for 3 hours. The mixture was cooled to 23 ° C, 100 parts of ethyl acetate was added to the resulting mixture, and the mixture was stirred at 23 ° C for 30 minutes. Thereafter, the supernatant was removed and concentrated. To the resulting concentrate, 100 parts of chloroform and 50 parts of ion-exchanged water were added, stirred at 23 ° C. for 30 minutes, and separated to recover the organic layer. This washing operation was performed 5 times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. The filtrate was concentrated, and 20 parts of acetonitrile was added to dissolve the resulting concentrate. This was concentrated, 40 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 40 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 14.81 parts of (B3).
MS (ESI (+) Spectrum): M ⁺ 281.0
MS (ESI (-) Spectrum): M ^- 409.0

Example 4: Synthesis of salt B4

20.00 parts of acetic anhydride and 5.00 parts of malonic acid were charged and stirred at 23 ° C. for 30 minutes. Thereafter, 0.24 part of sulfuric acid was added to the obtained mixture, stirred at 23 ° C. for 30 minutes, and 25.49 parts of (B4-a) was added. The resulting mixture was stirred at 23 ° C. for 30 minutes, heated to 80 ° C., and further stirred for 3 hours. The mixture was cooled to 23 ° C, 100 parts of ethyl acetate was added to the resulting mixture, and the mixture was stirred at 23 ° C for 30 minutes. Thereafter, the supernatant was removed and concentrated. To the obtained concentrate, 80 parts of chloroform and 40 parts of ion-exchanged water were charged, stirred at 23 ° C. for 30 minutes, and separated to recover the organic layer. This washing operation was performed 5 times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. The filtrate was concentrated, and 20 parts of acetonitrile was added to dissolve the resulting concentrate. This was concentrated, 30 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 30 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 9.84 parts of (B4).
MS (ESI (+) Spectrum): M ^<+> 207.1
MS (ESI (-) Spectrum): M ^- 409.0

Resin synthesis Monomers used for resin synthesis are shown below.

[Synthesis of Resin A1]
Monomer D, monomer E, monomer B, monomer C and monomer F were charged at 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%. This copolymer has a structural unit of the following formula, and this is designated as resin A1.

[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. 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. did. 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 of the following formula, and this is designated as resin A2.

Examples and Comparative Examples As shown in Table 1, chemical amplification was performed by filtering a mixture obtained by mixing and dissolving the above-described components and the following components through a fluororesin filter having a pore size of 0.2 μm. Type photoresist composition was prepared.

<Resin>
Resins A1 and A2 synthesized in the above synthesis example
<Acid generator>
Salts B1 to B4 synthesized in the above synthesis example and acid generator H1:

<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

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 above 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 the direct hot plate at the temperature described in the “PB” column of Table 1. An ArF excimer stepper for immersion exposure [XT: 1900 Gi; manufactured by ASML, NA = 1.35, 3/4 Annular XY polarized light] was used for the wafer formed with the resist composition film thus obtained. The line and space pattern was subjected to immersion exposure by changing the exposure amount stepwise.
Thereafter, post-exposure baking (PEB) was performed for 60 seconds on the hot plate at the temperature described in the “PEB” column of Table 1.
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.
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. The thing was set as x.
The results are shown in Table 2. The numerical value in the parenthesis indicates the touch width (nm) of the unevenness on the side wall.

  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.

Claims (6)

A salt represented by the formula (I).

[In the formula (I),
W is a ring represented by any one of formulas (a1-1) to (a1-3), and —CH ₂ — contained in the ring is —O—, —SO ₂ — or —CO—. The bond with L ¹ may be at any position.

L ¹ is a divalent group represented by any one of formula (b1-1), formula (b1-2), formula (b1-3), formula (b1-5) and formula (b1-6). Yes, a hydrogen atom contained in the divalent group may be substituted with a fluorine atom.

Where
L ^b2 represents a single bond or a saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^b3 represents a single bond or a saturated hydrocarbon group having 1 to 12 carbon atoms.
L ^b4 represents a saturated hydrocarbon group having 1 to 13 carbon atoms. However, the upper limit of the carbon number of L ^b3 and L ^b4 is 13.
L ^b5 represents a saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^b8 represents a saturated hydrocarbon group having 1 to 14 carbon atoms.
L ^b9 represents a saturated hydrocarbon group having 1 to 11 carbon atoms.
L ^b10 represents a saturated hydrocarbon group having 1 to 11 carbon atoms. However, the upper limit of the carbon number of L ^b9 and L ^b10 is 12.
Q ¹ and Q ² each independently represents a fluorine atom or a C 1-6 perfluoroalkyl group.
Z ⁺ represents an organic cation. ] The salt according to claim 1 represented by formula (II).

[In the formula (II), L ¹ , Q ¹ , Q ² and Z ⁺ represent the same meaning as described above. ]   The acid generator containing the salt of Claim 1 or 2.   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 dissolved in an alkaline aqueous solution by the action of an acid. A resist composition which is a resin to be obtained.   Furthermore, the resist composition of 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 method for producing a resist pattern, comprising a step of developing the heated composition layer using a developing device.