JP2012229199A - Salt, photoresist composition, and method for producing resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist composition capable of producing a resist pattern with an excellent focus margin (DOF).SOLUTION: There is provided a salt represented by formula (I), wherein Qand Qeach independently represent a fluorine atom or a 1-6C perfluoroalkyl group; Lrepresents *-CO-O-, *-CO-O-(CH)-CO-O-, *-CH-O-CO-, or *-CO-O-(CH)-O-CO- (wherein *represents a bonding hand with a carbon atom of -C(Q)(Q)-, and l represents an integer of 1-6); m represents an integer of 0-2, n represents an integer of 1-12, and o represents 0 or 1; Rrepresents a hydrogen atom, a fluorine atom, or a hydroxy group; and Z1represents an organic counter ion.

Description

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

  Patent Document 1 describes a resist composition containing p-tolyldiphenylsulfonium perfluorooctane sulfonate as a salt for an acid generator.

Japanese Patent Laid-Open No. 2002-296783

  Conventionally known photoresist compositions containing the above-mentioned acid generators may not always satisfy the CD uniformity (CDU) of the resulting pattern.

［式（Ｉ）中、
Ｑ^１及びＱ^２は、互いに独立に、フッ素原子又は炭素数１〜６のペルフルオロアルキル基を表す。
Ｌ^１は、＊^１−ＣＯ−Ｏ−、＊^１−ＣＯ−Ｏ−（ＣＨ_２）_ｌ−ＣＯ−Ｏ−、＊^１−ＣＨ_２−Ｏ−ＣＯ−又は＊^１−ＣＯ−Ｏ−（ＣＨ_２）_ｌ−Ｏ−ＣＯ−（＊^１は、−Ｃ（Ｑ^１）（Ｑ^２）−の炭素原子との結合手を表し、ｌは１〜６の整数を表す。）を表す。
ｍは０〜２の整数を表し、ｎは１〜１２の整数を表し、ｏは０又は１を表す。
Ｒ^１は、水素原子、フッ素原子又はヒドロキシ基を表す。）
Ｚ１^＋は、有機対イオンを表す。］ The present invention includes the following inventions.
[1] A salt represented by the formula (I).

[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
L ^{1 _{is, * 1 -CO-O -,}} * 1 -CO-O- (CH 2) l--CO O -, * 1 -CH 2 -O-CO- or ^* 1 -CO-O- (CH _{2) l -O-CO - (} * 1 ^{is, -C (Q 1) (Q} 2) - represents a bond to the carbon atoms of, l represents represents) an integer of 1-6..
m represents an integer of 0 to 2, n represents an integer of 1 to 12, and o represents 0 or 1.
R ¹ represents a hydrogen atom, a fluorine atom or a hydroxy group. )
Z1 ⁺ represents an organic counter ion. ]

[2] An acid generator containing the salt according to [1].
[3] The acid generator according to [2] and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution. A resist composition, which is a resin that can be dissolved in water.
[4] The resist composition according to [3], further including a basic compound.
[5] The resist composition according to [3] or [4], further including a basic compound.
[6] (1) A step of applying the resist composition according to any one of [3] to [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 including a step of developing the composition layer after heating.

  If the resist composition containing the salt of the present invention is used as an acid generator, a resist pattern having excellent CD uniformity (CDU) can be produced.

［式（Ｉ）中、
Ｑ^１及びＱ^２は、互いに独立に、フッ素原子又は炭素数１〜６のペルフルオロアルキル基を表す。
Ｌ^１は、＊^１−ＣＯ−Ｏ−、＊^１−ＣＯ−Ｏ−（ＣＨ_２）_ｌ−ＣＯ−Ｏ−、＊^１−ＣＨ_２−Ｏ−ＣＯ−又は＊^１−ＣＯ−Ｏ−（ＣＨ_２）_ｌ−Ｏ−ＣＯ−（＊^１は、−Ｃ（Ｑ^１）（Ｑ^２）−の炭素原子との結合手を表し、ｌは１〜６の整数を表す。）を表す。
ｍは０〜２の整数を表し、ｎは１〜１２の整数を表し、ｏは０又は１を表す。
Ｒ^１は、水素原子、フッ素原子またはヒドロキシ基を表す。）
Ｚ１^＋は、有機対イオンを表す。］
塩（Ｉ）のうち、正電荷を有する側を「有機カチオン」と、負電荷を有する側を「スルホン酸アニオン」と、それぞれ称することがある。 <Salt>
The salt of the present invention is a salt represented by the formula (I) (hereinafter sometimes referred to as “salt (I)”).

[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
L ^{1 _{is, * 1 -CO-O -,}} * 1 -CO-O- (CH 2) l--CO O -, * 1 -CH 2 -O-CO- or ^* 1 -CO-O- (CH _{2) l -O-CO - (} * 1 ^{is, -C (Q 1) (Q} 2) - represents a bond to the carbon atoms of, l represents represents) an integer of 1-6..
m represents an integer of 0 to 2, n represents an integer of 1 to 12, and o represents 0 or 1.
R ¹ represents a hydrogen atom, a fluorine atom or a hydroxy group. )
Z1 ⁺ represents an organic counter ion. ]
In the salt (I), the side having a positive charge may be referred to as an “organic cation”, and the side having a negative charge may be referred to as a “sulfonate anion”.

Examples of the perfluoroalkyl group of Q ¹ and Q ² include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluoro sec-butyl group, a perfluoro tert-butyl group, and a perfluoropentyl group. And perfluorohexyl group.
Q ¹ and Q ² in formula (I) are each independently preferably a trifluoromethyl group or a fluorine atom, more preferably a fluorine atom.

Examples of L ¹ include divalent groups represented by the following.

^{_{* 2 - (CH 2) m}} - (CF 2) n - (CH 2) o -R 1 (. * 2 is representative of a bond to ^{L 1)} include, for example, a group represented by the following Is mentioned.

Examples of the anion of the salt represented by the formula (I) include the sulfonate anions shown below.

Examples of the organic counter ion represented by Z1 ⁺ include organic onium cations such as an organic sulfonium cation, an organic iodonium cation, an organic ammonium cation, a benzothiazolium cation, and an organic phosphonium cation. Among these, an organic sulfonium cation and an organic iodonium cation are preferable, and an arylsulfonium cation is more preferable.

More preferably, an organic cation represented by any of the following formulas (b2-1) to (b2-4) [hereinafter, depending on the number of each formula, “cation (b2-1)”, “cation” (B2-2) "," cation (b2-3) "and" cation (b2-4) "in some cases.

In formula (b2-1) to formula (b2-4),
R ^b4 , R ^b5 and R ^b6 each independently represent an alkyl group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms. The hydrogen atom contained in the alkyl 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 is included in the alicyclic hydrocarbon group. The hydrogen atom may be substituted with a halogen atom, an acyl group having 2 to 4 carbon atoms or a glycidyloxy group, and the hydrogen atom contained in the aromatic hydrocarbon group is a halogen atom, a hydroxy group, or a carbon number of 1 It may be substituted with an aliphatic hydrocarbon group having 18 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. R ^b4 and R ^b5 may be combined to form a ring containing a sulfur atom.

The ring containing a sulfur atom which R ^b4 and R ^b5 may form together may be any of monocyclic, polycyclic, aromatic, non-aromatic, saturated and unsaturated rings. If it contains one or more sulfur atoms, it may further contain one or more sulfur atoms and / or one or more oxygen atoms. As the ring, a ring having 3 to 18 carbon atoms is preferable, and a ring having 4 to 13 carbon atoms is more preferable.

R ^b7 and R ^b8 each independently represent a hydroxy group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
m2 and n2 each independently represent an integer of 0 to 5. When m2 is 2 or more, all or some of the plurality of R ^b7 may be the same. When n2 is 2 or more, all or some of the plurality of R ^b8 may be the same.

R ^b9 and R ^b10 each independently represent an alkyl group having 1 to 18 carbon atoms or an alicyclic hydrocarbon group having 3 to 18 carbon atoms.
R ^b11 represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms.
R ^b12 represents an alkyl group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms, and hydrogen contained in the aromatic hydrocarbon group The atom may be substituted with an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or an alkylcarbonyloxy group having 1 to 12 carbon atoms. 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 alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
L ^b11 represents an oxygen atom or a sulfur atom.
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 o2 is 2 or more, all or some of the plurality of R ^b13 may be the same. When p2 is 2 or more, all or some of the plurality of R ^b14 may be the same. When q2 is 2 or more, all or some of the plurality of R ^b15 may be the same. When r2 is 2 or more, all or some of the plurality of R ^b16 may be the same. When s2 is 2 or more, all or some of the plurality of R ^b15 may be the same. When t2 is 2 or more, all or some of the plurality of R ^b18 may be the same.

芳香族炭化水素基としては、フェニル基、ナフチル基、アントリル基、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、トリル基、キシリル基、クメニル基、メシチル基、ビフェニル基、フェナントリル基、２，６−ジエチルフェニル基、２−メチル−６−エチルフェニル等のアリール基等が挙げられる。 Examples of the alkyl 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 and 2-ethylhexyl group. .
The alicyclic hydrocarbon group may be monocyclic or polycyclic. Examples of the monocyclic alicyclic hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, and dimethylcyclohexane. Examples thereof include a cycloalkyl group such as a hexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic saturated hydrocarbon group include decahydronaphthyl group, adamantyl group, norbornyl group, methylnorbornyl group, and the following groups. * Represents a bond with an adamantane ring or a cyclohexane ring.

Aromatic hydrocarbon groups include phenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl Groups, phenanthryl groups, 2,6-diethylphenyl groups, aryl groups such as 2-methyl-6-ethylphenyl, and the like.

Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a decyloxy group, and a dodecyloxy group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group.
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.

The alkyl group of R ^{b9 to} R ^b12 preferably has 1 to 12 carbon atoms, and in particular, a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group , A pentyl group, a hexyl group, an octyl group and a 2-ethylhexyl group are preferred.
The alicyclic hydrocarbon group of R ^{b9 to} R ^b11 preferably has 3 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, and in particular, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl. Group, cyclodecyl group, 2-alkyladamantan-2-yl group, 1- (adamantan-1-yl) alkane-1-yl group and isobornyl group are preferable.
The aromatic hydrocarbon group for R ^b12 includes a phenyl group, a 4-methylphenyl group, a 4-ethylphenyl group, a 4-tert-butylphenyl group, a 4-cyclohexylphenyl group, a 4-methoxyphenyl group, a biphenylyl group, and A naphthyl group and the like are preferable.
A group in which an aromatic hydrocarbon group of R ^b12 and an alkyl group are bonded is typically an aralkyl group.

Examples of the ring formed together with the sulfur atom to which R ^b9 and R ^b10 are bonded include, for example, a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and 1,4-oxathian-4-ium. A ring etc. are mentioned.
Examples of the ring formed with —CH—CO— in which R ^b11 and R ^b12 are bonded include an oxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, and an oxoadamantane ring.

  Specific examples of the organic counter ion represented by each of formula (b2-1) to formula (b2-4) include cations described in JP 2010-204646 A.

式（ｂ２−１−１）中、
Ｒ^b19、Ｒ^b20及び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１〜１８のアルキル基、炭素数３〜１８の脂環式炭化水素基又は炭素数１〜１２のアルコキシ基を表す。Ｒ^b19〜Ｒ^b21から選ばれる２つが一緒になってヘテロ原子を有してもよい環を形成してもよい。
ｖ２、ｗ２及びｘ２は、それぞれ独立に０〜５の整数を表す。
ｖ２が２以上のとき、複数のＲ^b19の全部又は一部は同じであってもよい。ｗ２が２以上のとき、複数のＲ^b20の全部又は一部は同じであってもよい。ｘ２が２以上のとき、複数のＲ^b21の全部又は一部は同じであってもよい。 Among these, a cation (b2-1) is preferable, and an organic counter ion represented by the following formula (b2-1-1) [hereinafter referred to as “cation (b2-1-1)” may be used. ], More preferably a triphenylsulfonium cation (in formula (b2-1-1), v2 = w2 = x2 = 0) or a tolylsulfonium cation (in formula (b2-1-1), v2 = w2 = X2 = 1, and R ^b19 , R ^b20 and R ^b21 are all methyl groups).

In formula (b2-1-1),
R ^b19 , R ^b20 and R ^b21 each independently represent a halogen atom (more preferably a fluorine atom), a hydroxy group, an alkyl group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or carbon. The number 1-12 alkoxy group is represented. ^{Two members} selected from R ^b19 to R ^b21 may be combined to form a ring which may have a hetero atom.
v2, w2 and x2 each independently represent an integer of 0 to 5.
When v2 is 2 or more, all or some of the plurality of R ^b19 may be the same. When w2 is 2 or more, all or some of the plurality of R ^b20 may be the same. When x2 is 2 or more, all or some of the plurality of R ^b21 may be the same.

The alkyl group of R ^{b19 to} R ^b21 preferably has 1 to 12 carbon atoms.
The alicyclic hydrocarbon group preferably has 4 to 18 carbon atoms.
Among them, R ^b19 , R ^b20 and 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. It is.
v2, w2 and x2 are preferably 0 or 1.

Examples of the cation (b2-1-1) include the following cations.

カチオン（ｂ２−３）としては、以下のカチオンが挙げられる。

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

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

Although salt (I) has been described for each of its sulfonate anion and organic counterion, salt (I) is a combination of the sulfonate anion and organic counterion. The sulfonate anion and the organic counter ion can be arbitrarily combined.
Examples of the salt (I) include the salts shown in Table 1 below.

Of these, the salts shown below are preferred.

In the compound represented by the salt (I), the compound represented by the formula (I1) in which L ¹ is * ¹ —CO—O— includes, for example, the compound represented by the formula (I1-a) and the formula (I It can be obtained by reacting the salt represented by I1-b) in a solvent. In the following formulas, Q ¹ and Q ² , m, n, o, R ¹ and Z1 ⁺ represent the same meaning as described above.
Examples of the solvent include chloroform.

Examples of the compound represented by the formula (I1-a) include compounds represented by the following.

式（Ｉ−ｃ）で表される塩は、例えば、特開２００８−１２７３６７号公報に記載された方法で合成することができる。 The compound represented by the formula (I1-b) can be obtained by reacting a salt represented by the formula (I1-c) with a compound represented by the formula (I1-d) in a solvent. .
Examples of the solvent include chloroform.

The salt represented by the formula (Ic) can be synthesized, for example, by the method described in JP 2008-127367 A.

溶媒としては、クロロホルム等が挙げられる。 In addition, in the compound represented by the salt (I), the compound represented by the formula (I2) in which L ¹ is * ¹ —CH ₂ —O—CO— is represented by, for example, the formula (I2-a). And a salt represented by the formula (I2-b) in a solvent.

Examples of the solvent include chloroform.

この反応の溶媒としては、クロロホルム、アセトニトリルなどが用いられる。
式（Ｉ２−ｃ）で表される化合物は、例えば、以下で表される化合物等が挙げられる。

The compound represented by the formula (I2-a) can be obtained by reacting the compound represented by the formula (I2-c) with the compound represented by the formula (I2-d) in a solvent. .

As a solvent for this reaction, chloroform, acetonitrile or the like is used.
Examples of the compound represented by the formula (I2-c) include compounds represented by the following.

この反応の溶媒としては、クロロホルムなどが用いられる。
この反応の還元剤としては、水素化アルミニウムリチウムなどが用いられる。
式（Ｉ２−ｅ）で表される化合物は、例えば、特開２００８−１３５５１号公報に記載された方法で製造することができる。 The salt represented by the formula (I2-b) can be obtained by reducing the salt represented by the formula (I2-e).

As a solvent for this reaction, chloroform or the like is used.
As a reducing agent for this reaction, lithium aluminum hydride or the like is used.
The compound represented by the formula (I2-e) can be produced, for example, by the method described in JP-A-2008-13551.

<Acid generator>
The acid generator of the present invention contains a salt (I). The acid generator of the present invention may contain one or more salts (I).
In addition, the acid generator of the present invention further includes a salt as a known acid generator other than the salt (I) (for example, an organic counter ion contained in the salt (I) and a known anion (included in the salt (I)). And a sulfonate anion contained in the salt (I) and a known cation (a salt comprising a cation other than the organic counter ion contained in the salt (I)). Also good. Salts other than the salt (I) contained in the acid generator may be referred to as “acid generator (B)”. The acid generator (B) may contain one or more salts.

  As an acid generator (B) used together with salt (I), the compound which consists of a sulfonate anion and organic sulfonium cation contained in salt (I) is mentioned. For example, what is represented by Formula (B1-1)-Formula (B1-20) is mentioned. Among these, those containing a triarylsulfonium cation are preferable, and a triphenylsulfonium cation and a tolylsulfonium cation are more preferable. In particular, Formula (B1-1), Formula (B1-2), Formula (B1-3), Formula (B1-6), Formula (B1-7), Formula (B1-11), Formula (B1-12) Further preferred are salts selected from formula (B1-13) and formula (B1-14).

In the acid generator, the content of the salt (I) is 5 parts by mass or more, preferably 10 parts by mass or more (more preferably 30 parts by mass or more), 100 parts by mass with respect to 100 parts by mass of the total amount of the acid generator. Part or less, preferably 95 parts by weight or less (more preferably 90 parts by weight or less).
The ratio (mass) of the content of the salt (I) and the acid generator (B) is, for example, 5:95 to 100: 0, preferably 5:95 to 95: 5, and more preferably 10:90. It is -90: 10, More preferably, it is 15: 85-85: 15, More preferably, it is 30: 70-70: 30.

<Resist composition>
The resist composition of the present invention includes the acid generator described above and a resin (hereinafter sometimes referred to as “resin (A)”).
The resist composition preferably further contains a basic compound (hereinafter sometimes referred to as “basic compound (C)”) and a solvent (hereinafter sometimes referred to as “solvent (E)”).

<Acid generator>
In the resist composition of the present invention, the content of the salt (I) is preferably 1 part by mass or more (more preferably 3 parts by mass or more), preferably 40 parts, relative to 100 parts by mass of the resin (A) described later. It is not more than part by mass (more preferably not more than 35 parts by mass).
When the salt (I) and the acid generator (B) are contained, the total content of the salt (I) and the acid generator (B) is 100 parts by mass of the resin (A). The amount 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 35 parts by mass or less).

<Resin (A)>
The resin (A) contained in the resist composition of the present invention is a resin having an acid labile group and insoluble or hardly soluble in an alkaline aqueous solution, and becomes soluble in an alkaline aqueous solution by the action of an acid. Resin. “Can be dissolved in an alkaline aqueous solution by the action of an acid” means “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”. means. The 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 alkali-soluble. 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.

In the present specification, "(meth) acrylic monomer", "CH ₂ = CH-CO-" or _{"CH 2 = C (CH 3)} -CO- " at least one monomer having the structure Means. 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.

<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 a group represented by the formula (1) and a group represented by the formula (2).

［式（１）中、Ｒ^a1〜Ｒ^a3は、それぞれ独立に、炭素数１〜８のアルキル基又は炭素数３〜２０の脂環式炭化水素基を表すか、Ｒ^a1及びＲ^a2は互いに結合して炭素数２〜２０の２価の炭化水素基を形成する。＊は結合手を表す。］

［式（２）中、Ｒ^ａ１’及びＲ^ａ２’は、それぞれ独立に、水素原子又は炭素数１〜１２の炭化水素基を表し、Ｒ^ａ３’は、炭素数１〜２０の炭化水素基を表すか、Ｒ^ａ２’及びＲ^ａ３’は互いに結合して炭素数２〜２０の２価の炭化水素基を形成し、該炭化水素基及び２価の基に含まれる−ＣＨ_２−は、−Ｏ―又は―Ｓ−で置き換わってもよい。］

In Expression (1), R ^a1 ~R ^a3 each independently represent a cycloaliphatic hydrocarbon radical of the alkyl group or 3 to 20 carbon atoms having 1 to 8 carbon atoms, R ^a1 and R ^a2 are each Bonding to form a divalent hydrocarbon group having 2 to 20 carbon atoms. * Represents a bond. ]

[In formula (2), R ^{a1 ′} and R ^{a2 ′} each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and R ^{a3 ′} represents a hydrocarbon group having 1 to 20 carbon atoms. R ^{a2 ′} and R ^{a3 ′} are bonded to each other to form a divalent hydrocarbon group having 2 to 20 carbon atoms, and —CH ₂ — contained in the hydrocarbon group and the divalent group is — O- or -S- may be substituted. ]

^Examples of the alkyl group represented by R ^{a1 to} R ^a3 include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group.
The alicyclic hydrocarbon group may be monocyclic or polycyclic. Examples of the monocyclic alicyclic hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, and dimethylcyclohexane. Examples thereof include a cycloalkyl group such as a hexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic saturated hydrocarbon group include a decahydronaphthyl group, an adamantyl group, a norbornyl group, a methylnorbornyl group, and the following groups. In the formula (1), the alicyclic hydrocarbon group preferably has 3 to 16 carbon atoms.

In the case where R ^a1 and R ^a2 are bonded to each other to form a divalent hydrocarbon group, examples of the —C (R ^a1 ) (R ^a2 ) (R ^a3 ) group include the following groups. The carbon number of the divalent hydrocarbon group is preferably 3 to 12 carbon atoms.

Examples of the acid labile group represented by the formula (1) include a 1,1-dialkylalkoxycarbonyl group (in the formula (1), R ^{a1 to} R ^a3 are alkyl groups, preferably tert- Butoxycarbonyl group), 2-alkyladamantan-2-yloxycarbonyl 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- (Adamantan-1-yl) -1-alkylalkoxycarbonyl group (in the formula (1), R ^a1 and R ^a2 are alkyl groups, and R ^a3 is an adamantyl group).

Examples of the hydrocarbon group for R ^{a1 ′ to} R ^{a3 ′} include an alkyl group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.
Examples of the alkyl group and alicyclic hydrocarbon group are the same as those described above.
Aromatic hydrocarbon groups include phenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl Groups, phenanthryl groups, 2,6-diethylphenyl groups, aryl groups such as 2-methyl-6-ethylphenyl, and the like.
Examples of the divalent hydrocarbon group include those similar to the divalent hydrocarbon group formed by combining R ^a1 and R ^a2 with each other.

Preferably, at least one of R ^{a1 ′} and R ^{a2 ′} is a hydrogen atom.
Specific examples of the group represented by the formula (2) include the following groups.

  The monomer (a1) having an acid labile group is preferably a monomer having an acid labile group and a carbon-carbon double bond, more preferably a (meth) acryl having an acid labile group. Monomer.

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

  The (meth) acrylic monomer having an acid labile group and an alicyclic hydrocarbon group is preferably a structural unit represented by the formula (a1-1) (hereinafter referred to as “structural unit (a1-1)”). Or a structural unit represented by formula (a1-2) or formula (a1-2) (hereinafter referred to as “structure”). And a monomer for deriving the unit (sometimes referred to as “a1-2)” (hereinafter, sometimes referred to as “monomer (a1-2)”). 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の整数を表し、＊は−ＣＯ−との結合手を表す。
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のアルキル基又は炭素数３〜１０の脂環式炭化水素基を表す。
ｍ１は０〜１４の整数を表す。
ｎ１は０〜１０の整数を表す。
ｎ１’は０〜３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—, k1 represents an integer of 1 to 7, and * represents a bond to —CO—. Represents a hand.
R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group.
R ^a6 and R ^a7 each independently represent an alkyl group having 1 to 8 carbon atoms or an alicyclic hydrocarbon group having 3 to 10 carbon atoms.
m1 represents the integer of 0-14.
n1 represents an integer of 0 to 10.
n1 ′ represents an integer of 0 to 3. ]

脂環式炭化水素基は、好ましくは炭素数８以下、より好ましくは６以下である。
ｍ１は、好ましくは０〜３の整数、より好ましくは０又は１である。
ｎ１は、好ましくは０〜３の整数、より好ましくは０又は１である。
ｎ１’は好ましくは０又は１である。 L ^a1 and L ^a2 are preferably —O— or ^* —O— (CH ₂ ) _k1 —CO—O—, more preferably —O—. k1 is preferably an integer of 1 to 4, more preferably 1.
R ^a4 and R ^a5 are preferably methyl groups.
^Examples of the alkyl group for R ^a6 and R ^a7 include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. The alkyl group for R ^a6 and R ^a7 preferably has 6 or less carbon atoms.
The alicyclic hydrocarbon group for R ^a6 and R ^a7 may be monocyclic or polycyclic, and examples of the monocyclic alicyclic hydrocarbon group include a cyclopentyl group, a cyclohexyl group, Examples thereof include cycloalkyl groups such as methylcyclohexyl group, dimethylcyclohexyl group, cycloheptyl group, and cyclooctyl group. Examples of the polycyclic saturated hydrocarbon group include a decahydronaphthyl group, an adamantyl group, a norbornyl group, a methylnorbornyl group, and the following groups.

The alicyclic hydrocarbon group preferably has 8 or less carbon atoms, more preferably 6 or less.
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.
n1 ′ is preferably 0 or 1.

Examples of the monomer represented by the formula (a1-1) include monomers described in JP 2010-204646 A. Monomers represented by the following formulas (a1-1-1) to (a1-1-8) are preferred, and monomers represented by the following formulas (a1-1-1) to (a1-1-4) are more preferred. .

Examples of the monomer represented by the formula (a1-2) include 1-ethylcyclopentan-1-yl (meth) acrylate, 1-ethylcyclohexane-1-yl (meth) acrylate, 1-ethylcycloheptane-1 -Yl (meth) acrylate, 1-methylcyclopentan-1-yl (meth) acrylate, 1-isopropylcyclopentan-1-yl (meth) acrylate and the like. Monomers represented by the following formulas (a1-2-1) to (a1-2-6) are preferred, and monomers represented by the following formulas (a1-2-3) to (a1-2-4) are more preferred. A monomer represented by the following formula (a1-2-3) is more preferable.

  The content of the structural unit (a1-1) and / or the structural unit (a1-2) in the resin (A) is usually 10 to 95 mol% in all structural units of the resin (A), preferably 15 to It is 90 mol%, More preferably, it is 20-85 mol%.

式（ａ１−５）中、
Ｒ^３１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、水素原子又はハロゲン原子を表す。
Ｌ^３〜Ｌ^５は、オキシ基、チオキシ基又は^＊−Ｏ−（ＣＨ₂）_k4−ＣＯ−Ｏ−で表される基を表す。ここで、ｋ４は１〜７の整数を表し、＊はカルボニル基（−ＣＯ−）との結合手である。
Ｚ^１’は、単結合又は炭素数１〜６のアルカンジイル基であり、該アルカンジイル基中に含まれるメチレン基は、オキシ基又はカルボニル基に置き換わっていてもよい。
ｓ１及びｓ１’は、それぞれ独立して、０〜４の整数を表す。 As the other monomer (a1), for example, a monomer represented by the formula (a1-5) which is a (meth) acrylic monomer having an acid labile group (2) (hereinafter referred to as “monomer (a1-5)”) May be used).

In formula (a1-5),
R ³¹ represents a C 1-6 alkyl group which may have a halogen atom, a hydrogen atom or a halogen atom.
L ^{3 to} L ⁵ represent an oxy group, a thioxy group, or a group represented by ^* —O— (CH ₂ ) _k4 —CO—O—. Here, k4 represents an integer of 1 to 7, and * is a bond with a carbonyl group (—CO—).
Z ^{1 ′} is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the methylene group contained in the alkanediyl group may be replaced with an oxy group or a carbonyl group.
s1 and s1 ′ each independently represents an integer of 0 to 4.

In formula (a1-5), R ³¹ is preferably a hydrogen atom, a methyl group, or a trifluoromethyl group.
L ⁵ is preferably an oxygen atom.
One of L ³ and L ⁴ is preferably an oxygen atom and the other is a sulfur atom.
s1 is preferably 1.
s1 ′ is preferably an integer of 0 to 2.
Z ^{1 ′} is preferably a single bond or —CH ₂ —CO—O—.

Examples of the monomer (a1-5) include the following monomers.

  When the resin (A) has a structural unit derived from the monomer (a1-5), the content thereof is in the range of 1 to 95 mol% with respect to all the structural units (100 mol%) of the resin (A). Is preferable, the range of 3-90 mol% is more preferable, and the range of 5-85 mol% is further more preferable.

<Acid stable monomer>
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 content of the structural unit derived from the monomer having an adamantyl group (particularly the monomer (a1-1) having an acid labile group) is preferably relative to the monomer (a1) having an acid labile group. 15 mol% or more. When the ratio of the monomer having an adamantyl group is increased, the dry etching resistance of the resist is improved.

  As an acid stable monomer, Preferably, the monomer which has a hydroxyl group or a lactone ring is mentioned. Acid-stable monomer having a hydroxy group (hereinafter sometimes referred to as “acid-stable monomer having a hydroxy group (a2)”) or 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 derived from (sometimes) 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 is preferably a phenolic hydroxy which is a hydroxystyrene. The acid-stable monomer (a2-0) having a group is used.
On the other hand, when using short-wavelength ArF excimer laser exposure (193 nm) or the like, the acid-stable monomer (a2) having a hydroxy group is preferably acid-stable having a hydroxyadamantyl group represented by the formula (a2-1) Use monomers. The acid-stable monomer (a2) having a hydroxy group may be used alone or in combination of two or more.

［式（ａ２−０）中、
Ｒ^a30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、水素原子又はハロゲン原子を表す。
Ｒ^a31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^a31は同一であっても異なってもよい。］ Examples of the monomer (a2-0) having a phenolic hydroxy group include styrene monomers such as p- or m-hydroxystyrene represented by the formula (a2-0).

[In the formula (a2-0),
R ^a30 represents a C 1-6 alkyl group which may have a halogen atom, a hydrogen atom or a halogen atom.
R ^a31 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 ^a31 may be the same or different. ]

^Examples of the alkyl group for R ^a30 and R ^a31 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, and n-hexyl group. Preferably, it is a C1-C4 alkyl group, More preferably, it is a C1-C2 alkyl group, Most preferably, it is a methyl group.
Examples of the alkoxy group for R ^a31 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. Preferably an alkoxy group having 1 to 4 carbon atoms, more preferably an alkoxy group having 1 or 2 carbon atoms, and particularly preferably a methoxy group.
Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group.
Examples of the acyloxy group include an acetyloxy group, a propionyloxy group, a butyryloxy group, and an isobutyryloxy group.
ma is preferably 0 to 2, more preferably 0 or 1, and particularly preferably 0.

In order to obtain a copolymer resin having a structural unit derived from a monomer having such a phenolic hydroxy group, the corresponding (meth) acrylic acid ester monomer and acetoxystyrene and / or other polymerizable monomer were radically polymerized. Thereafter, it can be obtained by deacetylation using a base.
As a monomer which has a phenolic hydroxy group, the monomer described in Unexamined-Japanese-Patent No. 2010-204634 is mentioned, for example. Monomers represented by the following formulas (a2-0-1) and (a2-0-2) are preferred. When the resin (A) is produced, it is possible to use a resin in which a phenolic hydroxy group in the resin (A) is protected with an appropriate protective group.

  When the resin (A) has a structural unit derived from the acid-stable monomer (a2-0), the content is usually from 5 to 90 mol%, preferably from 10 to 85 mol% in all units of the resin. More preferably, it is 15-80 mol%.

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。＊は−ＣＯ−との結合手を表す。
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。 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. * Represents a bond with -CO-.
R ^a14 represents a hydrogen atom or a methyl group.
R ^a15 and R ^a16 each independently represent a hydrogen atom, a methyl group or a hydroxy group.
o1 represents an integer 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 monomer described in Unexamined-Japanese-Patent No. 2010-204646 is mentioned, for example. Monomers represented by the following formulas (a2-1-1) to (a2-1-6) are preferable, respectively, and monomers represented by the following formulas (a2-1-1) to (a2-1-4) are respectively used. More preferred are monomers represented by the following formulas (a2-1-1) or (a2-1-3), respectively.

  When the resin (A) contains a structural unit derived from the monomer represented by the formula (a2-1), the content is usually 3 to 45 mol% in all units of the resin (A), preferably Is from 5 to 40 mol%, more preferably from 5 to 35 mol%, still more preferably from 5 to 20 mol%.

<Acid-stable monomer having a lactone ring (a3)>
The lactone ring possessed by the acid stable monomer (a3) may be, for example, a monocycle such as a β-propiolactone ring, γ-butyrolactone ring, or δ-valerolactone ring, and a monocyclic lactone ring and other rings The condensed ring may be used. Among these lactone rings, a γ-butyrolactone ring or a condensed ring of γ-butyrolactone ring and another ring is 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。＊は−ＣＯ−との結合手を表す。
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のアルキル基を表す。
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のアルキル基を表す。
ｑ１及びｒ１は、それぞれ独立に０〜３の整数を表す。
ｐ１が２以上のとき、複数のＲ^a21の全部又は一部は同じであってもよい。
ｑ１が２以上のとき、複数のＲ^a22の全部又は一部は同じであってもよい。
ｒ１が２以上のとき、複数のＲ^a23の全部又は一部は同じであってもよい。

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. * Represents a bond with -CO-.
R ^{a18 to} R ^a20 each independently represents a hydrogen atom or a methyl group.
R ^a21 represents an alkyl 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 alkyl group having 1 to 4 carbon atoms.
q1 and r1 each independently represents an integer of 0 to 3.
When p1 is 2 or more, all or some of the plurality of R ^a21 may be the same.
When q1 is 2 or more, all or some of the plurality of R ^a22 may be the same.
When r1 is 2 or more, all or some of the plurality of R ^a23 may be the same.

In Formula (a3-1) to Formula (a3-3), examples of L ^a4 , L ^a5, and L ^a6 include those described for L ^a3 .
L ^{a4 to} L ^a6 are each independently preferably —O— or ^* —O— (CH ₂ ) _k3 —CO—O—, more preferably —O—. k3 is preferably an integer of 1 to 4, more preferably 1.
R ^{a18 to} R ^a21 are each independently 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) having a lactone ring include monomers described in JP 2010-204646 A. The following formulas (a3-1-1) to (a3-1-4), (a3-2-1) to (a3-2-4), (a3-3-1) to (a3-3-4), respectively Are preferable, and monomers represented by the following formulas (a3-1-1) to (a3-1-2) and (a3-2-3) to (a3-2-4) are more preferable, respectively. More preferably, monomers represented by the following formula (a3-1-1) or (a3-2-3), respectively.

When the resin (A) contains a structural unit derived from the acid-stable monomer (a3) having a lactone ring, the total content is usually 5 to 70 mol% in all the structural units of the resin (A), Preferably it is 10-65 mol%, More preferably, it is 15-60 mol%.
The content of each of the structural unit derived from the monomer (a3-1), the structural unit derived from the monomer (a3-2), and the structural unit derived from the monomer (a3-3) is the total structure of the resin (A). 5-60 mol% is preferable with respect to a unit (100 mol%), the range of 5-50 mol% is more preferable, and the range of 10-50 mol% is especially preferable.

<Other monomer (a4)>
The resin may have a structural unit derived from another known monomer (a4) other than the monomers described above.

  Preferably, the resin (A) polymerizes at least the monomer (a1) having an acid labile group, the acid stable monomer (a2) having a hydroxy group, and / or the acid stable monomer (a3) having a lactone ring. Copolymer. In this 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. (More preferably, the monomer (a1-1) having an adamantyl group), and the acid-stable monomer (a2) having a hydroxy group is preferably an acid-stable monomer (a2-1) having a hydroxyadamantyl group, and a lactone ring More preferably, the acid-stable monomer (a3) having a γ-butyrolactone ring and an acid-stable monomer (a3-1) having a condensed ring of a γ-butyrolactone ring and a norbornane ring are used. At least one. 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 further preferably 4,000 or more. The upper limit of the weight average molecular weight is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 15,000 or less.
The content of the resin (A) is preferably 80% by mass or more and 99% by mass or less in the solid content of the composition. The “solid content in the composition” means the total of 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, for example, by a known analysis means such as liquid chromatography or gas chromatography.

<Basic compound (hereinafter sometimes referred to as “basic compound (C)”)>
The basic compound (C) acts as a quencher.
The basic compound (C) is preferably a basic nitrogen-containing organic compound, and examples thereof include amines and ammonium salts. Examples of amines include aliphatic amines and aromatic amines. Aliphatic amines include primary amines, secondary amines and tertiary amines. The basic compound (C) is preferably a compound represented by the formula (C1) to a compound represented by the formula (C8), more preferably a compound represented by the formula (C1-1). It is done.

［式（Ｃ１）中、Ｒ^c1、Ｒ^c2及びＲ^c3は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基、炭素数５〜１０の脂環式炭化水素基又は炭素数６〜１０の芳香族炭化水素基を表し、該アルキル基及び該脂環式炭化水素基に含まれる水素原子は、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、該芳香族炭化水素基に含まれる水素原子は、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５〜１０の脂環式炭化水素又は炭素数６〜１０の芳香族炭化水素基で置換されていてもよい。］

[In formula (C1), R ^c1 , R ^c2 and R ^c3 each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alicyclic hydrocarbon group having 5 to 10 carbon atoms, or 6 to 6 carbon atoms. 10 represents an aromatic hydrocarbon group, and the hydrogen atom contained in the alkyl group and the alicyclic hydrocarbon group may be substituted with a hydroxy group, an amino group or an alkoxy group having 1 to 6 carbon atoms, The hydrogen atom contained in the aromatic hydrocarbon group is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alicyclic hydrocarbon having 5 to 10 carbon atoms, or an aromatic group having 6 to 10 carbon atoms. It may be substituted with a group hydrocarbon group. ]

［式（Ｃ１−１）中、Ｒ^c2及びＲ^c3は、上記と同じ意味を表す。
Ｒ^c4は、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５〜１０の脂環式炭化水素又は炭素数６〜１０の芳香族炭化水素基を表す。
ｍ３は０〜３の整数を表し、ｍ３が２以上のとき、複数のＲ^c4は、互いに同一でも異なってもよい。］

[In Formula (C1-1), R ^c2 and R ^c3 represent the same meaning as described above.
R ^c4 represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alicyclic hydrocarbon having 5 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms.
m3 represents an integer of 0 to 3, and when m3 is 2 or more, a plurality of R ^{c4 s} may be the same as or different from each other. ]

［式（Ｃ２）、式（Ｃ３）及び式（Ｃ４）中、Ｒ^c5、Ｒ^c6、Ｒ^c7及びＲ^c8は、それぞれ独立に、Ｒ^c1と同じ意味を表す。
Ｒ^c9は、炭素数１〜６のアルキル基、炭素数３〜６の脂環式炭化水素基又は炭素数２〜６のアルカノイル基を表す。
ｎ３は０〜８の整数を表し、ｎ３が２以上のとき、複数のＲ^c9は、互いに同一でも異なってもよい。］

[In Formula (C2), Formula (C3) and Formula (C4), R ^c5 , R ^c6 , R ^c7 and R ^c8 each independently represent the same meaning as R ^c1 .
R ^c9 represents an alkyl group having 1 to 6 carbon atoms, an alicyclic hydrocarbon group having 3 to 6 carbon atoms, or an alkanoyl group having 2 to 6 carbon atoms.
n3 represents an integer of 0 to 8, and when n3 is 2 or more, the plurality of R ^c9 may be the same as or different from each other. ]

［式（Ｃ５）及び式（Ｃ６）中、Ｒ^c10、Ｒ^c11、Ｒ^c12、Ｒ^c13及びＲ^c16は、それぞれ独立に、Ｒ^c1と同じ意味を表す。
Ｒ^c14、Ｒ^c15及びＲ^c17は、それぞれ独立に、Ｒ^c4と同じ意味を表す。
ｏ３及びｐ３は、それぞれ独立に０〜３の整数を表し、ｏ３又はｐ３が２以上であるとき、それぞれ、複数のＲ^c14及びＲ^c15は互いに同一でも異なってもよい。
Ｌ^c1は、炭素数１〜６のアルカンジイル基、−ＣＯ−、−Ｃ（＝ＮＨ）−、−Ｓ−又はこれらを組合せた２価の基を表す。］

[In Formula (C5) and Formula (C6), R ^c10 , R ^c11 , R ^c12 , R ^c13 and R ^c16 each independently represent the same meaning as R ^c1 .
R ^c14 , R ^c15 and R ^c17 each independently represent the same meaning as R ^c4 .
o3 and p3 each independently represent an integer of 0 to 3, and when o3 or p3 is 2 or more, the plurality of R ^c14 and R ^c15 may be the same as or different from each other.
L ^c1 represents an alkanediyl group having 1 to 6 carbon atoms, —CO—, —C (═NH) —, —S—, or a divalent group obtained by combining these. ]

［式（Ｃ７）及び式（Ｃ８）中、Ｒ^c18、Ｒ^c19及びＲ^c20は、それぞれ独立に、Ｒ^c4と同じ意味を表す。
ｑ３、ｒ３及びｓ３は、それぞれ独立に０〜３の整数を表し、ｑ３、ｒ３及びｓ３が２以上であるとき、それぞれ、複数のＲ^c18、Ｒ^c19及びＲ^c20は互いに同一でも異なってもよい。
Ｌ^c2は、単結合又は炭素数１〜６のアルカンジイル基、−ＣＯ−、−Ｃ（＝ＮＨ）−、−Ｓ−又はこれらを組合せた２価の基を表す。］

Wherein (C7) and formula ^{(C8), R c18, R} c19 and R ^c20 in each occurrence independently represent the same meaning as R ^c4.
q3, r3 and s3 each independently represent an integer of 0 to 3, q3, when r3 and s3 is 2 or more, each of a plurality of R ^c18, R ^c19 and R ^{c 20} may be the same or different from each other .
L ^c2 represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, —CO—, —C (═NH) —, —S—, or a divalent group obtained by combining these. ]

In the formulas (C1) to (C8), examples of the alkyl group, the alicyclic hydrocarbon group, the aromatic hydrocarbon group, the alkoxy group, and the alkanediyl group are the same as those described above.
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.

  Examples of the compound represented by the formula (C1) include 1-naphthylamine, 2-naphthylamine, aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, N-methylaniline, N, N- Dimethylaniline, diphenylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine, tripropylamine, tributylamine, tri Pentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyl Hexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine, methyldinonylamine, methyldidecylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonyl Amine, ethyldidecylamine, dicyclohexylmethylamine, tris [2- (2-methoxyethoxy) ethyl] amine, triisopropanolamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diamino-1,2- Examples include diphenylethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, 4,4′-diamino-3,3′-diethyldiphenylmethane, and preferably diisopropyl. Piruanirin. Particularly preferred include 2,6-diisopropylaniline.

Examples of the compound represented by the formula (C2) include piperazine.
Examples of the compound represented by the formula (C3) include morpholine.
Examples of the compound represented by the formula (C4) include piperidine and hindered amine compounds having a piperidine skeleton described in JP-A No. 11-52575.
Examples of the compound represented by the formula (C5) include 2,2′-methylenebisaniline.
Examples of the compound represented by the formula (C6) include imidazole and 4-methylimidazole.
Examples of the compound represented by the formula (C7) include pyridine and 4-methylpyridine.
Examples of the compound represented by the formula (C8) include 1,2-di (2-pyridyl) ethane, 1,2-di (4-pyridyl) ethane, 1,2-di (2-pyridyl) ethene, 1, 2-di (4-pyridyl) ethene, 1,3-di (4-pyridyl) propane, 1,2-di (4-pyridyloxy) ethane, di (2-pyridyl) ketone, 4,4′-dipyridyl sulfide 4,4′-dipyridyl disulfide, 2,2′-dipyridylamine, 2,2′-dipiconylamine, bipyridine and the like.

  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.

  The content of the basic compound (C) is preferably about 0.01 to 5% by mass, more preferably about 0.01 to 3% by mass, and particularly preferably based on the solid content of the resist composition. It is about 0.01-1 mass%.

<Solvent (sometimes referred to as "solvent (E)")
The resist composition of the present invention preferably contains a solvent (E). The content of the solvent (E) is, for example, 90% by mass or more, preferably 92% by mass or more, more preferably 94% by mass or more in the resist composition, for example, 99.9% by mass or less, preferably Is contained at 99% by 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. There is no particular limitation on the component (F), and additives known in the resist field, for example, polymer compounds other than the resin (A) (for example, the above-mentioned acid-stable monomer and / or copolymer of known monomers), Sensitizers, dissolution inhibitors, surfactants, stabilizers, dyes and the like can be used.

<Method for preparing resist composition>
The resist composition comprises a resin (A), an acid generator represented by the formula (I), optionally an acid generator (B), a solvent (E), a basic compound (C) or other component (F). It can be prepared by mixing. The mixing order is arbitrary and is not particularly limited. The temperature at the time of mixing can select an appropriate temperature range from the range of 10-40 degreeC according to the kind etc. of resin, the solubility with respect to solvent (E), such as resin. What is necessary is just to select mixing time according to mixing temperature, and 0.5 to 24 hours are preferable. The mixing means is not particularly limited, and stirring and mixing can be used.

  Thus, the resin (A) of the acid generator represented by formula (I) and the acid generator (B), solvent (E), basic compound (C) or component (F) used as necessary After mixing each with a preferable content, a resist composition can be prepared by filtering using a filter having a pore size of about 0.003 to 0.2 μm.

<Method for producing resist pattern>
The method for producing a resist pattern of the present invention comprises:
(1) The process of apply | coating the resist composition of this invention 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;
(4) A step of heating the composition layer after exposure,
(5) A step of developing the composition layer after heating 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. Drying is performed by, for example, heating means using a heating device such as a hot plate (so-called pre-baking), decompressing means using a decompressing device, or a combination of these means. The temperature in this case is preferably about 50 to 200 ° C., for example. The pressure is preferably 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 (photomask) on which a required pattern is formed. Exposure light sources include those that emit laser light in the ultraviolet region such as KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F ₂ excimer laser (wavelength 157 nm), solid-state laser light source (YAG or semiconductor laser) Etc.) can be used such as those that convert the wavelength of the laser light from the above and radiate the harmonic laser light in the far ultraviolet region or the vacuum ultraviolet region. The exposure machine may irradiate an electron beam or extreme ultraviolet light (EUV). In this specification, irradiating these radiations may be collectively referred to as “exposure”.

The composition layer after exposure is subjected to heat treatment (so-called post-exposure baking) 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 includes a resist composition for KrF excimer laser exposure, a resist composition for ArF excimer laser exposure, a resist composition for electron beam (EB) irradiation, or a resist composition or liquid for an EUV exposure machine. It is suitable as a resist composition for immersion exposure and useful for fine processing of semiconductors.

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 determined by gel permeation chromatography.
Apparatus: HLC-8120GPC type (manufactured by Tosoh Corporation)
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)
Further, the structure of the compound was confirmed by measuring molecular peaks using mass spectrometry (LC is Agilent Model 1100, MS is Agilent LC / MSD Model). In the following examples, the value of this molecular peak is indicated by “MS”.

式（Ｉ１−１）で表される塩を、特開２００８−１２７３６７号公報に記載された方法で合成した。
式（Ｉ１−１）で表される塩７．００部及びクロロホルム４２．００部を仕込み、２３℃で３０分間攪拌し、式（Ｉ１−２）で表される化合物２．７２部を仕込み、６０℃で１時間攪拌した。得られた反応物を２３℃まで冷却し、ろ過することにより、式（Ｉ１−３）で表される化合物を含む溶液を得た。式（Ｉ１−３）で表される化合物を含む溶液に、式（Ｉ１−４）で表される化合物６．９０部を仕込み、２３℃で３時間攪拌した。得られた反応物に、クロロホルム２８．００部及びイオン交換水２１．００部を仕込み、攪拌、分液を行った。水洗を５回行った。得られた有機層を濃縮し、得られた濃縮物をアセトニトリル２６．００部に溶解し、濃縮した。得られた濃縮物に、ｔｅｒｔ−ブチルメチルエーテル３０．００部を加えて攪拌し、上澄液を除去した。得られた残渣をアセトニトリルに溶解し、濃縮することにより、式（Ｉ１）で表される塩８．８４部を得た。 Example 1: Synthesis of a salt represented by the formula (I1)

The salt represented by the formula (I1-1) was synthesized by the method described in JP 2008-127367 A.
7.00 parts of the salt represented by the formula (I1-1) and 42.00 parts of chloroform were charged, stirred at 23 ° C. for 30 minutes, and 2.72 parts of the compound represented by the formula (I1-2) were charged. Stir at 60 ° C. for 1 hour. The obtained reaction product was cooled to 23 ° C. and filtered to obtain a solution containing the compound represented by the formula (I1-3). A solution containing the compound represented by the formula (I1-3) was charged with 6.90 parts of the compound represented by the formula (I1-4) and stirred at 23 ° C. for 3 hours. To the obtained reaction product, 28.00 parts of chloroform and 21.00 parts of ion-exchanged water were added, followed by stirring and liquid separation. Water washing was performed 5 times. The obtained organic layer was concentrated, and the resulting concentrate was dissolved in 26.00 parts of acetonitrile and concentrated. To the resulting concentrate, 30.00 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 8.84 parts of the salt represented by the formula (I1).

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 588.9

式（Ｉ１８５−１）で表される化合物４．４６部及びアセトニトリル５０部を仕込み、４０℃で３０分間攪拌した。その後、式（Ｉ１８５−２）で表される化合物１．６２部を添加し、６０℃程度まで昇温した後、同温度で２時間攪拌し、式（Ｉ１８５−３）で表される化合物を含む溶液を得た。

クロロホルム１３．５０部に、０℃で、水素化アルミニウムリチウム０．３４部を少しづつ添加した。次いで、式（Ｉ１８５−４）で表される塩４．５３部及びクロロホルム１３．５９部の混合溶液を滴下し、２３℃で１８時間攪拌した。その後、得られた反応マスに、６Ｎ塩酸５．００部を滴下攪拌後、ろ過した。回収されたろ液を濃縮し、回収された残渣に、アセトニトリル１５部を添加し、２３℃で３０分間攪拌することにより、式（Ｉ１８５−５）で表される化合物を含む溶液を得た。

式（Ｉ１８５−５）で表される化合物を含む溶液に、先に得られた式（Ｉ１８５−３）で表される化合物を含む溶液を滴下し、２３℃で１８時間攪拌した。得られた反応物に、クロロホルム５０部及びイオン交換水２０部を加え、２３℃で３０分間攪拌した。その後、静置し、分液して有機層を得た。この水洗操作をさらに５回繰り返した。回収された有機層に活性炭１．００部を加えて攪拌し、ろ過した。回収されたろ液を濃縮した。得られた濃縮物に、アセトニトリル２０部を添加して溶解し、濃縮し、酢酸エチル３０部を加えて攪拌し、上澄液を除去した。得られた残渣にｔｅｒｔ−ブチルメチルエーテル３０部を加えて攪拌し、ろ過することにより、式（Ｉ１８５）で表される塩４．８３部を得た。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ２６３．１
ＭＡＳＳ（ＥＳＩ（−）Ｓｐｅｃｔｒｕｍ）：Ｍ⁻ ５８８．９ Example 2: Synthesis of a salt represented by the formula (I185)

4.46 parts of a compound represented by the formula (I185-1) and 50 parts of acetonitrile were charged and stirred at 40 ° C. for 30 minutes. Thereafter, 1.62 parts of the compound represented by the formula (I185-2) was added, and the temperature was raised to about 60 ° C., followed by stirring at the same temperature for 2 hours to obtain the compound represented by the formula (I185-3). A solution containing was obtained.

To 13.50 parts of chloroform, 0.34 parts of lithium aluminum hydride was added little by little at 0 ° C. Subsequently, a mixed solution of 4.53 parts of the salt represented by the formula (I185-4) and 13.59 parts of chloroform was dropped, and the mixture was stirred at 23 ° C. for 18 hours. Thereafter, 5.00 parts of 6N hydrochloric acid was added dropwise to the resulting reaction mass, followed by filtration. The collected filtrate was concentrated, 15 parts of acetonitrile was added to the collected residue, and the mixture was stirred at 23 ° C. for 30 minutes to obtain a solution containing the compound represented by the formula (I185-5).

The solution containing the compound represented by the formula (I185-3) obtained previously was added dropwise to the solution containing the compound represented by the formula (I185-5), followed by stirring at 23 ° C. for 18 hours. To the obtained reaction product, 50 parts of chloroform and 20 parts of ion-exchanged water were added and stirred at 23 ° C. for 30 minutes. Then, it left still and liquid-separated and obtained the organic layer. This washing operation was further repeated 5 times. To the collected organic layer, 1.00 part of activated carbon was added, stirred and filtered. The collected filtrate was concentrated. The obtained concentrate was dissolved by adding 20 parts of acetonitrile, concentrated, added with 30 parts of ethyl acetate and stirred, and the supernatant was removed. To the obtained residue, 30 parts of tert-butyl methyl ether was added, stirred and filtered to obtain 4.83 parts of the salt represented by the formula (I185).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (−) Spectrum): M ^- 588.9

Resin Synthesis The compounds (monomers) used in the resin synthesis are shown below. These monomers are referred to as “monomer (A)” to “monomer (H)”.

[Synthesis of Resin A1]
Monomer (D), monomer (E), monomer (B), monomer (C) and monomer (F) are mixed in a molar ratio [monomer (D): monomer (E): monomer (B): monomer (C): Monomer (F)] was mixed at 30: 14: 6: 20: 30, and 1.5 mass times of dioxane was further mixed into this monomer mixture with respect to the total mass of all monomers. Into the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were respectively added to 1.00 mol% and 3.00 mol% with respect to the total number of moles of all monomers. Polymerization was carried out by heating at 73 ° C. for about 5 hours. Thereafter, the polymerization reaction solution was poured into a large amount of a mixed solvent of methanol and water (mass ratio methanol: water = 4: 1) to precipitate the resin. This resin was filtered and collected. This is dissolved again in dioxane, poured into a large amount of methanol / water mixed solvent to precipitate the resin, and the precipitated resin is filtered and recovered twice, followed by reprecipitation purification, weight average molecular weight Of about 8.1 × 10 ³ was obtained in a yield of 65%. This copolymer has the following structural units, and is designated as resin A1.

[Synthesis of Resin A2]
Monomer (A), monomer (E), monomer (B), monomer (C), and monomer (F) are in a molar ratio [monomer (A): monomer (E): monomer (B): monomer (C): Monomer (F)] was mixed at 30: 14: 6: 20: 30, and 1.5 mass times dioxane was further mixed with respect to the total mass of all monomers. Into the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were respectively added to 1.00 mol% and 3.00 mol% with respect to the total number of moles of all monomers. Polymerization was carried out by heating at 73 ° C. for about 5 hours. Thereafter, the polymerization reaction solution was poured into a large amount of a mixed solvent of methanol and water (mass ratio methanol: water = 4: 1) to precipitate the resin. This resin was filtered and collected. This is dissolved again in dioxane, poured into a large amount of methanol / water mixed solvent to precipitate the resin, and the precipitated resin is filtered and recovered three times to perform reprecipitation purification, and the weight average molecular weight A copolymer having a yield of about 7.8 × 10 ³ was obtained with a yield of 68%. This copolymer has the following structural units and is designated as resin A2.

[Synthesis of Resin A3]
Monomer (A), monomer (B) and monomer (G) are mixed so that the molar ratio [monomer (A): monomer (B): monomer (G)] is 50:25:25, , 1.5 mass times dioxane was mixed with respect to the total mass of all monomers. To the resulting mixture, azobisisobutyronitrile as an initiator was added at a ratio of 2 mol% with respect to the total number of moles of all monomers, and this was heated at 85 ° C. for about 5 hours for polymerization. Went. Thereafter, the polymerization reaction liquid was poured into a large amount of n-heptane to precipitate the resin. This resin was filtered and collected. This is dissolved again in dioxane, poured into a large amount of n-heptane to precipitate the resin, and the precipitated resin is filtered and recovered three times for reprecipitation purification, and the weight average molecular weight is about 9. A copolymer of 3 × 10 ³ was obtained with a yield of 29%. This copolymer has structural units derived from the following monomers, and is referred to as Resin A3.

[Synthesis of Resin A4]
Monomer (D), monomer (E), monomer (B), monomer (F), and monomer (C) are in a molar ratio [monomer (D): monomer (E): monomer (B): monomer (F): Monomer (C)] was mixed at 30: 14: 6: 20: 30, and 1.5 mass times dioxane of the total monomer amount was added to prepare a solution. To this solution, 1 mol% and 3 mol% of azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were added to the total monomer amount, respectively, and these were heated at 75 ° C. for about 5 hours. did. The obtained reaction mixture was poured into a large amount of methanol / water mixed solvent to precipitate the resin, and this resin was filtered. The obtained resin was dissolved again in dioxane, and the resulting solution was poured into a methanol / water mixed solvent to precipitate the resin, followed by two reprecipitation operations of filtering the resin, and a weight average molecular weight of 7.0. A × 10 ³ resin A4 (copolymer) was obtained in a yield of 60%. This resin A4 has the following structural units.

[Synthesis of Resin A5]
Monomer (D), monomer (H), monomer (B), monomer (F) and monomer (C) are in a molar ratio [monomer (D): monomer (H): monomer (B): monomer (F): Monomer (C)] was mixed at 30: 14: 6: 20: 30, and 1.5 mass times dioxane of the total monomer amount was added to prepare a solution. To this solution, 1 mol% and 3 mol% of azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were added to the total monomer amount, respectively, and these were heated at 75 ° C. for about 5 hours. did. The obtained reaction mixture was poured into a large amount of methanol / water mixed solvent to precipitate the resin, and this resin was filtered. The obtained resin was again dissolved in dioxane, and the resulting solution was poured into a methanol / water mixed solvent to precipitate the resin, followed by two reprecipitation operations of filtering the resin, and a weight average molecular weight of 7.4. × give 10 ^third resin A5 (copolymer) in 62% yield. This resin A5 has the following structural units.

<Preparation of resist composition>
As shown in Table 2, the following components were mixed, and the resulting mixture was filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist composition.

酸発生剤Ｂ２：ｐ−トリルジフェニルスルホニウム パーフルオロオクタンスルホネート（特開２００２−２９６７８３号公報の実施例に従って合成） <Resin>
Resins A1 to A5
<Acid generator>
Acid generator I1: salt represented by formula (I1) Acid generator I185: salt represented by formula (I185) Acid generator B1: synthesized according to examples of JP 2010-152341 A

Acid generator B2: p-tolyldiphenylsulfonium perfluorooctane sulfonate (synthesized according to Examples in Japanese Patent Application Laid-Open No. 2002-296783)

<Basic compound: Quencher>
Quencher C1: 2,6-diisopropylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.)
<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

<Immersion exposure evaluation of resist composition>
An organic antireflective coating composition (ARC-29; manufactured by Nissan Chemical Co., Ltd.) is applied to a silicon wafer and baked at 205 ° C. for 60 seconds to form an organic reflective film having a thickness of 78 nm on the wafer. A prevention film was formed. Next, the resist composition was applied (spin coated) on the organic antireflection film so that the film thickness after drying (pre-baking) was 85 nm. After coating, the silicon wafer was pre-baked on a direct hot plate at the temperature described in the “PB” column of Table 2 for 60 seconds to form a composition layer. ArF excimer stepper for immersion exposure (XT: 1900 Gi; manufactured by ASML, NA = 1.35, 3/4 Annular XY polarized light) on a silicon wafer on which the composition layer is formed, and a contact hole pattern (hole pitch 100 nm) Using a mask for forming a hole diameter of 70 nm), the exposure amount was changed stepwise to perform exposure. Note that ultrapure water was used as the immersion medium.
After the exposure, the silicon wafer was heated (post-exposure baking process) on a hot plate at the temperature described in the “PEB” column of Table 2 for 60 seconds. Next, this silicon wafer was subjected to paddle development for 60 seconds with a 2.38% tetramethylammonium hydroxide aqueous solution to obtain a resist pattern.

  In the resist pattern obtained after development, the exposure amount at which the hole diameter formed using a mask was 55 nm was defined as the effective sensitivity.

<CD Uniformity (CDU) evaluation>
In terms of effective sensitivity, the hole diameter of a pattern formed with a mask having a hole diameter of 70 nm was measured 24 times per hole, and the average value was taken as the average hole diameter of one hole. A standard deviation is obtained using a population obtained by measuring 400 average hole diameters of a pattern formed with a mask having a hole diameter of 70 nm in the same wafer,
When the standard deviation is less than 1.85 nm,
When the standard deviation is 1.85 nm or more and less than 2.00 nm, “◯”,
A standard deviation of 2.00 nm or more was judged as “x”.
The results are shown in Table 3.

  If the resist composition containing the salt of the present invention is used, a resist pattern having excellent CD uniformity (CDU) can be produced.

Claims (6)

A salt represented by the formula (I).

[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group.
L ^{1 _{is, * 1 -CO-O -,}} * 1 -CO-O- (CH 2) l--CO O -, * 1 -CH 2 -O-CO- or ^* 1 -CO-O- (CH _{2) l -O-CO - (} * 1 ^{is, -C (Q 1) (Q} 2) - represents a bond to the carbon atoms of, l represents represents) an integer of 1-6..
m represents an integer of 0 to 2, n represents an integer of 1 to 12, and o represents 0 or 1.
R ¹ represents a hydrogen atom, a fluorine atom or a hydroxy group. )
Z1 ⁺ represents an organic counter ion. ]   An acid generator containing the salt according to claim 1.   A resin comprising an acid generator according to claim 2 and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, and can be dissolved in an alkaline aqueous solution by the action of an acid. Resist composition which is resin.   Furthermore, the resist composition of Claim 3 containing a solvent.   Furthermore, the resist composition of Claim 3 or 4 containing a basic compound. (1) The process of apply | coating the resist composition in any one of Claims 3-5 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;
(4) A step of heating the composition layer after exposure,
(5) a step of developing the composition layer after heating;
A method for producing a resist pattern including: