JP6135058B2 - Resist composition and method for producing resist pattern - Google Patents

Description

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

  A chemically amplified resist composition used for microfabrication of a semiconductor using a lithography technique includes an acid generator composed of a salt, a resin that 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. Containing.

For example, Patent Document 1 describes a resist composition containing an acid generator composed of a salt represented by the following formula (Z1) and a resin.
.

JP 2011-75827 A

  In the conventional resist compositions, the line edge roughness (LER) at the time of producing a resist pattern may not always be sufficient.

［式（Ｉ）中、
Ｑ^１及びＱ^２は、同一又は相異なり、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、炭素数１〜１７の２価の脂肪族飽和炭化水素基を表し、該２価の脂肪族飽和炭化水素基を構成するメチレン基は、酸素原子又はカルボニル基に置き換わっていてもよい。
Ｘ^１は、単結合又は−ＮＲ^１−を表す。
Ｘ^２は、炭素数１〜６の２価の脂肪族炭化水素基を表す。
Ｗは、炭素数３〜３６の脂環式炭化水素基を表し、該脂環式炭化水素基を構成するメチレン基は、酸素原子、硫黄原子、カルボニル基又はスルホニル基で置き換わっていてもよく、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、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基、炭素数３〜１２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に置き換わっていてもよい。
Ｒ^１は、水素原子又は炭素数１〜６のアルキル基を表す。
Ｚ^＋は、有機カチオンを表す。］
〔２〕 式（Ｉ）のＷが、アダマンチル基、シクロヘキシル基又はノルボルニル基であり、該アダマンチル基、シクロヘキシル基又はノルボルニル基を構成するメチレン基は、酸素原子、硫黄原子、カルボニル基又はスルホニル基で置き換わっていてもよく、該アダマンチル基、シクロヘキシル基又はノルボルニル基に含まれる水素原子は、ヒドロキシ基、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基、炭素数３〜１２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に置き換わっていてもよい〔１〕記載のレジスト組成物。
〔３〕 式（Ｉ）のＬ^１が、＊−ＣＯ−Ｏ−（ＣＨ_２）_ｕ１−Ｏ−ＣＯ−（ＣＨ_２）_ｕ２−又は式（Ｌ^１−Ａ）で表される基である〔１〕又は〔２〕記載のレジスト組成物。

（ｕ１及びｕ２は、同一又は相異なり、１〜６の整数を表す。ｕ３は、０又は１を表す。
＊は、Ｑ^１及びＱ^２と結合した炭素原子との結合手を表す。）
〔４〕 式（Ｉ）のＬ^１が、式（Ｌ^１−Ａ）で表される基である〔１〕又は〔２〕記載のレジスト組成物。

（ｕ３は、０又は１を表す。＊は、Ｑ^１及びＱ^２と結合した炭素原子との結合手を表す。
）
〔５〕 式（Ｉ）のＬ^１が、式（Ｌ^１−Ａ）で表される基であり、かつＸ^１が単結合である〔１〕又は〔２〕記載のレジスト組成物。

（ｕ３は、０又は１を表す。＊は、Ｑ^１及びＱ^２と結合した炭素原子との結合手を表す。
）
〔６〕 式（Ｉ）のＺ^＋が、トリアリールスルホニウムカチオンである〔１〕〜〔５〕のいずれか記載のレジスト組成物。
〔７〕 樹脂が、以下の式（ａ１−２）で表される構造単位を有する樹脂である〔１〕〜〔６〕のいずれか記載のレジスト組成物。

［式（ａ１−２）中、
Ｌ^a2は、酸素原子又は＊−Ｏ−（ＣＨ₂）_k1−ＣＯ−Ｏ−（ｋ１は１〜７の整数を表し、＊はカルボニル基との結合手を表す。）で表される基を表す。
Ｒ^a5は、水素原子又はメチル基を表す。
Ｒ^a7は、炭素数１〜１０の脂肪族炭化水素基を表す。
ｎ１は０〜１０の整数を表す。
ｎ１’は０〜３の整数を表す。］
〔８〕 さらに、塩基性化合物を含有する〔１〕〜〔７〕のいずれか記載のレジスト組成物。
〔９〕（１）〔１〕〜〔８〕のいずれか記載のレジスト組成物を基板上に塗布する工程、
（２）塗布後の組成物を乾燥して組成物層を形成する工程、
（３）組成物層に露光する工程、
（４）露光後の組成物層を加熱する工程、及び
（５）加熱後の組成物層を現像する工程、
を含むレジストパターンの製造方法。
〔１０〕
以下の式（Ｉ）で表される塩。

［式（Ｉ）中、
Ｑ^１及びＱ^２は、同一又は相異なり、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、炭素数１〜１７の２価の脂肪族飽和炭化水素基を表し、該２価の脂肪族飽和炭化水素基を構成するメチレン基は、酸素原子又はカルボニル基に置き換わっていてもよい。
Ｘ^１は、単結合又は−ＮＲ^１−を表す。
Ｘ^２は、炭素数１〜６の２価の脂肪族炭化水素基を表す。
Ｗは、炭素数３〜３６の脂環式炭化水素基を表し、該脂環式炭化水素基を構成するメチレン基は、酸素原子、硫黄原子、カルボニル基又はスルホニル基で置き換わっていてもよく、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、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基、炭素数３〜１２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に置き換わっていてもよい。
Ｒ^１は、水素原子又は炭素数１〜６のアルキル基を表す。
Ｚ^＋は、有機カチオンを表す。］ The present invention includes the following inventions.
[1] A resist composition containing a salt represented by the formula (I) and a resin that 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.

[In the formula (I),
Q ¹ and Q ² are the same or different and each represents a fluorine atom or a C 1-6 perfluoroalkyl group.
L ¹ represents a divalent aliphatic saturated hydrocarbon group having 1 to 17 carbon atoms, and the methylene group constituting the divalent aliphatic saturated hydrocarbon group may be replaced by an oxygen atom or a carbonyl group. .
X ¹ represents a single bond or —NR ¹ —.
X ² represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.
W represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, and the methylene group constituting the alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group, The hydrogen atom contained in the alicyclic hydrocarbon group is a hydroxy group, 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 12 carbon atoms, or a carbon number. It may be replaced by 6-10 aromatic hydrocarbon groups.
R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Z ⁺ represents an organic cation. ]
[2] W in formula (I) is an adamantyl group, cyclohexyl group or norbornyl group, and the methylene group constituting the adamantyl group, cyclohexyl group or norbornyl group is an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group. The hydrogen atom contained in the adamantyl group, cyclohexyl group or norbornyl group may be a hydroxy group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a fatty acid having 3 to 12 carbon atoms. The resist composition according to [1], which may be substituted with a cyclic hydrocarbon group or an aromatic hydrocarbon group having 6 to 10 carbon atoms.
[3] L ^{1 in the} formula (I) is a group represented by * —CO—O— (CH ₂ ) _u1 —O—CO— (CH ₂ ) _u2 — or the formula (L ¹ -A) [ [1] or [2].

(U1 and u2 are the same or different and represent an integer of 1 to 6. u3 represents 0 or 1.
* Represents a bond with a carbon atom bonded to Q ¹ and Q ² . )
[4] The resist composition according to [1] or [2], wherein L ^{1 in the} formula (I) is a group represented by the formula (L ¹ -A).

(U3 represents 0 or 1. * represents a bond with a carbon atom bonded to Q ¹ and Q ² .
)
[5] The resist composition according to [1] or [2], wherein L ^{1 in the} formula (I) is a group represented by the formula (L ¹ -A) and X ¹ is a single bond.

(U3 represents 0 or 1. * represents a bond with a carbon atom bonded to Q ¹ and Q ² .
)
[6] The resist composition according to any one of [1] to [5], wherein Z ^{+ in} formula (I) is a triarylsulfonium cation.
[7] The resist composition according to any one of [1] to [6], wherein the resin is a resin having a structural unit represented by the following formula (a1-2).

[In the formula (a1-2),
L ^a2 represents an oxygen atom or a group represented by * —O— (CH ₂ ) _k1 —CO—O— (k1 represents an integer of 1 to 7, and * represents a bond to a carbonyl group). Represent.
R ^a5 represents a hydrogen atom or a methyl group.
R ^a7 represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms.
n1 represents an integer of 0 to 10.
n1 ′ represents an integer of 0 to 3. ]
[8] The resist composition according to any one of [1] to [7], further containing a basic compound.
[9] (1) A step of applying the resist composition according to any one of [1] to [8] on a substrate,
(2) A step of drying the composition after application to form a composition layer,
(3) a step of exposing the composition layer;
(4) a step of heating the composition layer after exposure, and (5) a step of developing the composition layer after heating,
A method for producing a resist pattern including:
[10]
A salt represented by the following formula (I):

[In the formula (I),
Q ¹ and Q ² are the same or different and each represents a fluorine atom or a C 1-6 perfluoroalkyl group.
L ¹ represents a divalent aliphatic saturated hydrocarbon group having 1 to 17 carbon atoms, and the methylene group constituting the divalent aliphatic saturated hydrocarbon group may be replaced by an oxygen atom or a carbonyl group. .
X ¹ represents a single bond or —NR ¹ —.
X ² represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.
W represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, and the methylene group constituting the alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group, The hydrogen atom contained in the alicyclic hydrocarbon group is a hydroxy group, 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 12 carbon atoms, or a carbon number. It may be replaced by 6-10 aromatic hydrocarbon groups.
R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Z ⁺ represents an organic cation. ]

  If the resist composition of this invention is used, the resist pattern which has the outstanding line edge roughness (LER) can be obtained.

The resist composition of the present invention (hereinafter sometimes referred to as “the present resist composition”)
A resin that 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 (hereinafter, sometimes referred to as “resin (A)”)
The salt represented by the formula (I) (hereinafter sometimes referred to as “salt (I)”)
Containing.
The resist composition further contains a basic compound (hereinafter sometimes referred to as “basic compound (C)”) and a solvent (hereinafter sometimes referred to as “solvent (D)”). It is preferable.
Hereinafter, the constituent components of the resist composition will be described in the order of the salt (I), the resin (A), the basic compound (C) and the solvent (D) contained in the resist composition as necessary. The method for preparing the resist composition and the method for producing a resist pattern using the resist composition will be described.

In the present specification, unless otherwise specified, the following examples of substituents are applied to any chemical structural formula having the same substituents while appropriately selecting the number of carbon atoms. Among the aliphatic hydrocarbon groups, those that can be linear or branched, such as an alkyl group, include any of them. When stereoisomers exist, all stereoisomers are included. In the following examples of substituents, the numerical value attached to “C” indicates the number of carbon atoms of each group.
Further, 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.

The hydrocarbon group includes an aliphatic hydrocarbon group and an aromatic hydrocarbon group.
The aliphatic hydrocarbon group includes both a chain type and a cyclic type, and includes a combination of a chain type and an alicyclic aliphatic hydrocarbon group unless otherwise defined. Further, these aliphatic hydrocarbon groups may contain a carbon-carbon double bond in a part thereof, but a saturated group (aliphatic saturated hydrocarbon group) is preferable.

Of the chain aliphatic hydrocarbon groups, the monovalent one typically includes an alkyl group. Specific examples of the alkyl group include a methyl group (C ₁ ), an ethyl group (C ₂ ), a propyl group (C ₃ ), a butyl group (C ₄ ), a pentyl group (C ₅ ), a hexyl group (C ₆ ), heptyl _(C 7), octyl _(C 8), decyl (C _10), dodecyl (C _12), hexadecyl (C _14), pentadecyl (C _15), hexyl decyl group (C _16), A heptadecyl group (C ₁₇ ) and an octadecyl group (C ₁₈ ).
Examples of the divalent group of chain aliphatic hydrocarbon groups include alkanediyl groups in which one hydrogen atom has been removed from an alkyl group. Specific examples of the alkanediyl group include 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 -1,17-diyl group, ethane-1,1-diyl group, propane-1,1-diyl group, propane-2,2-diyl group, butane-1,3-diyl group, 2-methylpropane-1 , 3- Yl group, 2-methylpropane-1,2-diyl, pentane-1,4-diyl group and 2-methylbutane-1,4-diyl group and the like.

  The cyclic aliphatic hydrocarbon group (hereinafter sometimes referred to as “alicyclic hydrocarbon group” in some cases) is typically a cycloalkyl group, and any of the monocyclic and polycyclic groups shown below can be used. Is also included.

As a monovalent alicyclic hydrocarbon group, a monocyclic aliphatic hydrocarbon group represents 1 hydrogen atom of a cycloalkane represented by the following formulas (KA-1) to (KA-7). It is a group that has been removed.

The polycyclic aliphatic hydrocarbon group is a group in which one hydrogen atom of a cycloalkane represented by the following formulas (KA-8) to (KA-22) is removed.

  Examples of the divalent alicyclic hydrocarbon group include groups in which two hydrogen atoms have been removed from the alicyclic hydrocarbon of formula (KA-1) to formula (KA-22).

  The aliphatic hydrocarbon group may have a substituent. Such a substituent is defined each time, and examples thereof include a halogen atom, a hydroxy group, an alkoxy group, an acyl group, an acyloxy group, an aryl group, an aralkyl group, and an aryloxy group.

Examples of alkoxy groups include methoxy group (C ₁ ), ethoxy group (C ₂ ), propoxy group (C ₃ ), butoxy group (C ₄ ), pentyloxy group (C ₅ ), hexyloxy group (C ₆ ), heptyl Examples thereof include an oxy group (C ₇ ), an octyloxy group (C ₈ ), a decyloxy group (C ₁₀ ), and a dodecyloxy group (C ₁₂ ).
Examples of the acyl group include acetyl group (C ₂ ), propionyl group (C ₃ ), butyryl group (C ₄ ), valeryl group (C ₅ ), hexanoyl group (C ₆ ), heptanoyl group (C ₇ ), octanoyl group ( C ₈ ), decanoyl group (C ₁₀ ) and dodecanoyl group (C ₁₂ ) and other alkyl groups and carbonyl groups bonded, and benzoyl group (C ₇ ) and other aryl groups and carbonyl groups bonded Can be mentioned.
Examples of the acyloxy group include an acetyloxy group, a propionyloxy group, a butyryloxy group, and an isobutyryloxy group.
Examples of the aralkyl group include benzyl group (C ₇ ), phenethyl group (C ₈ ), phenylpropyl group (C ₉ ), naphthylmethyl group (C ₁₁ ), and naphthylethyl group (C ₁₂ ).
Aryloxy groups include phenyloxy group (C ₆ ), naphthyloxy group (C ₁₀ ), anthryloxy group (C ₁₄ ), biphenyloxy group (C ₁₂ ), phenanthryloxy group (C ₁₄ ) and full A combination of an aryl group such as an oleenyloxy group (C ₁₃ ) and an oxygen atom is exemplified.

The monovalent aromatic hydrocarbon group typically includes an aryl group.
Examples of the aryl group include a phenyl group (C ₆ ), a naphthyl group (C ₁₀ ), an anthryl group (C ₁₄ ), a biphenyl group (C ₁₂ ), a phenanthryl group (C ₁₄ ), and a fluorenyl group (C ₁₃ ). . Examples of the divalent aromatic hydrocarbon group include an arylene group in which one hydrogen atom is further removed from the aryl group exemplified here.

  The aromatic hydrocarbon group may also have a substituent. Although such a substituent is defined each time, a halogen atom, an alkoxy group, an acyl group, an alkyl group, and an aryloxy group can be mentioned. Among these, the alkyl group is the same as those exemplified as the chain aliphatic hydrocarbon group, and among the substituents optionally present in the aromatic hydrocarbon group, those other than the alkyl group are aliphatic hydrocarbon groups. The same thing as what was illustrated as a substituent of is included.

  Hereinafter, the components of the resist composition will be described.

［式（Ｉ）中、
Ｑ^１及びＱ^２は、同一又は相異なり、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、炭素数１〜１７の２価の脂肪族飽和炭化水素基を表し、該２価の脂肪族飽和炭化水素基を構成するメチレン基は、酸素原子又はカルボニル基に置き換わっていてもよい。
Ｘ^１は、単結合又は−ＮＲ^１−を表す。
Ｘ^２は、炭素数１〜６の２価の脂肪族炭化水素基を表す。
Ｗは、炭素数３〜３６の脂環式炭化水素基を表し、該脂環式炭化水素基を構成するメチレン基は、酸素原子、硫黄原子、カルボニル基又はスルホニル基で置き換わっていてもよく、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、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基、炭素数３〜１２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に置き換わっていてもよい。
Ｒ^１は、水素原子又は炭素数１〜６のアルキル基を表す。
Ｚ^＋は、有機カチオンを表す。］ <Salt (I)>
The salt (I) is represented by the formula (I) as described above.

[In the formula (I),
Q ¹ and Q ² are the same or different and each represents a fluorine atom or a C 1-6 perfluoroalkyl group.
L ¹ represents a divalent aliphatic saturated hydrocarbon group having 1 to 17 carbon atoms, and the methylene group constituting the divalent aliphatic saturated hydrocarbon group may be replaced by an oxygen atom or a carbonyl group. .
X ¹ represents a single bond or —NR ¹ —.
X ² represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.
W represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, and the methylene group constituting the alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group, The hydrogen atom contained in the alicyclic hydrocarbon group is a hydroxy group, 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 12 carbon atoms, or a carbon number. It may be replaced by 6-10 aromatic hydrocarbon groups.
R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Z ⁺ represents an organic cation. ]

The salt (I) contained in the resist composition is a novel and useful salt as an acid generator, and the present invention includes an invention relating to the salt (I).
In the following description, those having a negative charge obtained by removing the organic cation (Z ⁺ ) from the salt (I) are sometimes referred to as “sulfonate anions”.

First, the sulfonate anion constituting the salt (I) will be described.
Q ¹ and Q ² are the same or different and each represents a fluorine atom or a C 1-6 perfluoroalkyl group. Examples of the perfluoroalkyl group include those in which all the hydrogen atoms contained in the alkyl group in the alkyl group having 1 to 6 carbon atoms already exemplified are replaced with fluorine atoms. Specific examples include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group, and a perfluorohexyl group. Here, the perfluoroalkyl group has been described with specific examples thereof, but Q ¹ and Q ² are the same or different and are preferably a fluorine atom or a trifluoromethyl group, and both Q ¹ and Q ² are fluorine atoms. Further preferred.

The divalent aliphatic saturated hydrocarbon group represented by L ¹ is an alkanediyl group exemplified above in the range of 1 to 17 carbon atoms, any of the above-mentioned formulas (KA-1) to (KA-22). Examples thereof include a divalent alicyclic hydrocarbon group obtained by removing two hydrogen atoms from a cyclic hydrocarbon. The alkanediyl group may be linear or branched. In addition, the divalent aliphatic saturated hydrocarbon group of L ^{1 is} a divalent group in which an alkanediyl group and a divalent alicyclic hydrocarbon group are arbitrarily combined as long as the carbon number is 17 or less. But you can.

The methylene group constituting the aliphatic saturated hydrocarbon group for L ¹ may be replaced with an oxygen atom or a carbonyl group. As described above, the salt (I) having a group in which the methylene group constituting the aliphatic saturated hydrocarbon group is replaced by an oxygen atom or a carbonyl group as L ¹ is considered in view of the ease of production of the salt (I). It is preferable. In addition, the manufacturing method of salt (I) is mentioned later.

式（ｂ１−１）〜式（ｂ１−８）中、
Ｌ^b2は、炭素数１〜１５の２価の脂肪族飽和炭化水素基を表す。
Ｌ^b3及びＬ^b4は、互いに独立に、炭素数１〜１２の２価の脂肪族飽和炭化水素基を表す。但しＬ^b3及びＬ^b4の合計炭素数の上限は１３である。
Ｌ^b5及びＬ^b6は、互いに独立に、炭素数１〜１４の２価の脂肪族飽和炭化水素基を表す。但しＬ^b5及びＬ^b6の合計炭素数の上限は１５である。
Ｌ^b７及びＬ^b８は、互いに独立に、炭素数１〜１５の２価の脂肪族飽和炭化水素基を表す。但しＬ^b７及びＬ^b８の合計炭素数の上限は１６である。
Ｌ^b9は、単結合又は炭素数１〜１３の２価の脂肪族飽和炭化水素基を表す。
Ｌ^b10は、炭素数１〜１４の２価の脂肪族飽和炭化水素基を表す。但しＬ^b9及びＬ^b10の合計炭素数の上限は１４である。
Ｌ^b11及びＬ^b13は、互いに独立に、炭素数１〜１１の２価の脂肪族飽和炭化水素基を表す。
Ｌ^b12は、単結合又は炭素数１〜１０の２価の脂肪族飽和炭化水素基を表す。但しＬ^b11、Ｌ^b12及びＬ^b13の合計炭素数の上限は１２である。
Ｌ^b14及びＬ^b16は、それぞれ独立に、炭素数１〜１３の２価の脂肪族飽和炭化水素基を表す。
Ｌ^b15は、単結合又は炭素数１〜１２の２価の脂肪族飽和炭化水素基を表す。但しＬ^b14、Ｌ^b15及びＬ^b16の合計炭素数の上限は１４である。
Ｌ^b17及びＬ^b18は、互いに独立に、炭素数１〜１２の２価の脂肪族飽和炭化水素基を表す。但しＬ^b17及びＬ^b18の合計炭素数の上限は１３である。 Specific examples of the group in which the methylene group constituting the divalent aliphatic saturated hydrocarbon group of L ¹ is replaced with an oxygen atom or a carbonyl group include, for example, the following formulas (b1-1) to (b1-8) ) Or a group represented by any of the above. L ¹ is preferably a group represented by any one of the formula (b1-1), the formula (b1-2), the formula (b1-5), or the formula (b1-8), and more preferably the formula (b1 -1), a group represented by formula (b1-5) or formula (b1-8). Note that * represents a bond in formula (b1-1) ~ formula (b1-8), the left and right have been described in conjunction in formula (I), and the left bond is the ^{Q 1} and ^{Q 2} bound to the carbon atom attached, right bond is bound to X ^1. The same applies to specific examples of formula (b1-1) to formula (b1-8) shown below.

In formula (b1-1) to formula (b1-8),
L ^b2 represents a divalent aliphatic saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^b3 and L ^b4 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms. However, the upper limit of the total carbon number of L ^b3 and L ^b4 is 13.
L ^b5 and L ^b6 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 14 carbon atoms. However, the upper limit of the total carbon number of L ^b5 and L ^b6 is 15.
L ^b7 and L ^b8 each independently represent a C 1-15 divalent aliphatic saturated hydrocarbon group. However, the upper limit of the total carbon number of L ^b7 and L ^b8 is 16.
L ^b9 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 13 carbon atoms.
L ^b10 represents a divalent aliphatic saturated hydrocarbon group having 1 to 14 carbon atoms. However, the upper limit of the total carbon number of L ^b9 and L ^b10 is 14.
L ^b11 and L ^b13 each independently represent a ^C 1-11 divalent aliphatic saturated hydrocarbon group.
L ^b12 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 10 carbon atoms. However, the upper limit of the total carbon number of L ^b11 , L ^b12 and L ^b13 is 12.
L ^b14 and L ^b16 each independently represent a C 1-13 divalent aliphatic saturated hydrocarbon group.
L ^b15 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms. However, the upper limit of the total carbon number of L ^b14 , L ^b15 and L ^b16 is 14.
L ^b17 and L ^b18 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms. However, the upper limit of the total carbon number of L ^b17 and L ^b18 is 13.

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 divalent group represented by the formula (b1-7) include the following.

Examples of the divalent group represented by the formula (b1-8) include the following.

（ｕ３は０又は１を表す。＊は、Ｑ^１及びＱ^２と結合した炭素原子との結合手を表す。） Among them, L ¹ is a divalent group represented by the formula (b1-1), a divalent group represented by the formula (b1-5), and a divalent group represented by the formula (b1-8). Preferably, L ^b2 is a divalent group represented by the formula (b1-1) which is a saturated hydrocarbon group having 1 to 6 carbon atoms, L ^b9 is a single bond, and L ^b10 is 1 to 12 carbon atoms. A divalent group represented by the formula (b1-5) which is a saturated hydrocarbon group, L ^b17 is a saturated hydrocarbon group having 1 to 6 carbon atoms, and L ^b18 is a saturated hydrocarbon group having 1 to 12 carbon atoms. More preferably, it is a divalent group represented by the formula (b1-8), and * —CO—O— (CR ² R ³ ) _v — (R ² and R ³ are each independently a hydrogen atom or carbon. Represents an alkyl group of 1 to 6. v represents an integer of 1 to 6. When v is 2 or more, R ² and R ³ may be the same or different, and * is bonded to Q ¹ and Q ² With carbon atoms A group represented by: * —CO—O— (CH ₂ ) _w —O— (w represents an integer of 1 to 6. * represents a carbon atom bonded to Q ¹ and Q ² . A group represented by formula (L ¹ -A), * -CO—O—L ² —O—CO—CH ₂ — (L ² is the number of carbon atoms) It represents a divalent aliphatic saturated hydrocarbon group of 1 to 12. * represents a bond to a carbon atom bonded to Q ¹ and Q ² ). CO—O—CH ₂ —, * —CO—O—C (CH ₃ ) ₂ —, * —CO—O— (CH ₂ ) ₂ —O—, a group represented by the formula (L ¹ -A), * —CO—O— (CH ₂ ) _u1 —O—CO— (CH ₂ ) _u2 — (u1 and u2 are the same or different and represent an integer of 1 to 6. * represents Q ¹ and Q ² Bonded carbon atoms Is particularly preferable. Among _{them, * - CO-O- (CH} 2) u1 -O-CO- (CH 2) u2 - or particularly preferably a group represented by the formula ^(L 1 -A), in the formula ^(L 1 -A) The group represented is most preferred.

(U3 expressed. * Is a is 0 or 1, represents a bond to the carbon atom bonded with ^{Q 1} and ^{Q 2.)}

X ¹ represents a single bond or —NR ¹ —.
Specific examples of R ¹ include a hydrogen atom or an alkyl group already exemplified in the range of 1 to 6 carbon atoms. Among them, a hydrogen atom and a methyl group are preferable, and a hydrogen atom is more preferable.
X ² represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms. Examples of the divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms include a methylene group, an ethylene group, a propane-1,3-diyl group, a propane-1,2-diyl group, a butane-1,4-diyl group, A pentane-1,5-diyl group, a hexane-1,6-diyl group and the like can be mentioned. Among them, a methylene group or an ethylene group is preferable, and a methylene group is more preferable.

  As the alicyclic hydrocarbon group having 3 to 36 carbon atoms represented by W, a cycloalkyl group is preferable, and the cycloalkane represented by any one of the formulas (KA-1) to (KA-22) described above. The group which removed one hydrogen atom is mentioned.

Examples of the group in which the methylene group constituting the alicyclic hydrocarbon group is replaced with an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group include the groups represented below.

Examples of the alkyl group having 1 to 12 carbon atoms that may replace the hydrogen atom contained in the alicyclic hydrocarbon group include a methyl group (C ₁ ), an ethyl group (C ₂ ), a propyl group (C ₃ ), and butyl. Group (C ₄ ), pentyl group (C ₅ ), hexyl group (C ₆ ), heptyl group (C ₇ ), octyl group (C ₈ ), decyl group (C ₁₀ ), dodecyl group (C ₁₂ ) and the like. It is done.

Examples of the alkoxy group having 1 to 12 carbon atoms that may replace the hydrogen atom contained in the alicyclic hydrocarbon group include a methoxy group (C ₁ ), an ethoxy group (C ₂ ), a propoxy group (C ₃ ), and butoxy. group _(C 4), a pentyloxy group _(C 5), a hexyloxy group _(C 6), heptyloxy group (C _7), octyloxy group (C _8), decyloxy group (C ₁₀₎ and dodecyl group (C ₁₂ ).

The aromatic hydrocarbon group having 6 to 10 carbon atoms that may be replaced with a hydrogen atom contained in the alicyclic hydrocarbon group is typically an aryl group, and includes a phenyl group (C ₆ ) and a naphthyl group ( C ₁₀ ) and the like.

  As the alicyclic hydrocarbon group having 3 to 12 carbon atoms that may be replaced with a hydrogen atom contained in the alicyclic hydrocarbon group, a cycloalkyl group is preferable, and the above-described formulas (KA-1) to (KA-) are preferable. 10), a group in which one hydrogen atom of the cycloalkane represented by any one of (KA-13), (KA-14) and (KA-16) is removed.

  W is preferably an adamantyl group, a cyclohexyl group or a norbornyl group, and the methylene group constituting the adamantyl group, cyclohexyl group or norbornyl group may be replaced by an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group, The hydrogen atom contained in the adamantyl group, cyclohexyl group or norbornyl group is a hydroxy group, 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 12 carbon atoms or carbon. The aromatic hydrocarbon group of several 6-10 may be substituted.

As mentioned above, regarding the sulfonic acid anion constituting the salt (I), each of Q ¹ , Q ² , L ¹ , X ¹ , X ² and W has been described with reference to specific examples and preferred examples. The specific example of the sulfonate anion which comprises salt (I) is shown.

Next, the organic cation (Z ⁺ ) constituting the salt (I) will be described.
Examples of the organic cation represented by Z ⁺ 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, Z ⁺ is an organic cation represented by any one of the following formulas (b2-1) to (b2-4) (hereinafter, depending on the number of each formula, in some cases, “cation (b2 -1) "," cation (b2-2) "," cation (b2-3) "and" cation (b2-4) "].

In formula (b2-1) to formula (b2-4),
R ^{b4 to} R ^b6 each independently represent an aliphatic hydrocarbon group having 1 to 30 carbon atoms, a saturated cyclic 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 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 cyclic hydrocarbon group May be substituted with a halogen atom, an acyl group having 2 to 4 carbon atoms, or a glycidyloxy group. The hydrogen atom contained in the aromatic hydrocarbon group may be a halogen atom, a hydroxy group, or a carbon atom. It may be substituted with an aliphatic hydrocarbon group having 1 to 18 carbon atoms, a saturated cyclic 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 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. When m2 is an integer of 2 or more, the plurality of R ^b7 may be the same or different from each other. When n2 is an integer of 2 or more, the plurality of R ^b8 are the same or different from each other. May be.

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 ^{b9 to} R ^b11 each independently represents an alkyl having 1 to 18 carbon atoms or an alicyclic hydrocarbon group having 3 to 18 carbon atoms. As for carbon number of this alkyl group, 1-12 are preferable. As for carbon number of this alicyclic hydrocarbon group, 4-12 are preferable.
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 and / or R ^b11 and R ^b12 are independently bonded to each other, and together with the atoms to which they are bonded, a 3- to 12-membered ring (preferably a 3- to 7-membered ring) Ring), and the methylene group contained in these rings may be replaced by an oxygen atom, a sulfur atom or a carbonyl group.

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 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 an integer of 2 or more, the plurality of R ^b13 may be the same or different from each other. When p2 is an integer of 2 or more, the plurality of R ^b14 are the same or different from each other. When s2 is an integer of 2 or more, the plurality of R ^b17 may be the same as or different from each other. When u2 is an integer of 2 or more, the plurality of R ^b18 are the same as each other. When q2 is an integer of 2 or more, the plurality of R ^b15 may be the same or different from each other. When r2 is an integer of 2 or more, the plurality of R ^b16 are They may be the same or different.

The alkylcarbonyloxy group for R ^b12 is a group in which the acyl group already exemplified and an oxygen atom are bonded.

Preferred examples of the alkyl group ^{represented by} R ^{b9 to} R ^b12 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, and an octyl group. And 2-ethylhexyl group.
Preferable examples of the alicyclic hydrocarbon group represented by R ^{b9 to} R ^b11 include 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.
Preferred examples of the aromatic hydrocarbon group for R ^b12 include phenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-cyclohexylphenyl group, 4-methoxyphenyl group, And biphenylyl and naphthyl groups.
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 by combining the combination of R ^b9 and R ^b10 include, for example, a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathian-4-ium ring. Etc.
Examples of the ring formed by combining the combination of R ^b11 and R ^b12 include an oxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, and an oxoadamantane ring.

  Specific examples of the organic cation represented by each of the formulas (b2-1) to (b2-4) include cations described in JP2010-204646A. Among these, a cation (b2-1), a cation (b2-2), and a cation (b2-3) are preferable, and a cation (b2-1) is particularly preferable. Specific examples of cation (b2-2) and cation (b2-3) are given below. In addition, the specific example of a cation (b2-1) will mention later the more preferable specific example of a cation (b2-1-1).

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

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

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の脂肪族炭化水素基又は炭素数１〜１２のアルコキシ基を表す。また、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。
この脂肪族炭化水素基の炭素数は１〜１２であると好ましく、炭素数１〜１２のアルキル基及び炭素数４〜１８の脂環式炭化水素基がより好ましく、さらには置換基として、ハロゲン原子、ヒドロキシ基、炭素数１〜１２のアルコキシ基、炭素数６〜１８の芳香族炭化水素基、炭素数２〜４のアシル基又はグリシジルオキシ基を有していてもよい。
ｖ２、ｗ２及び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。
なかでも、Ｒ^b19、Ｒ^b20及び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。 As described above, among the organic cations constituting the salt (I), the cation (b2-1) is preferable, and the organic cation represented by the following formula (b2-1-1) [hereinafter referred to as “cation (b2)” -1-1) ". ], 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 aliphatic hydrocarbon group having 1 to 18 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. It is also possible to form two of which may have a hetero atom together ring selected from R ^b19 to R ^b21.
The aliphatic hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms and an alicyclic hydrocarbon group having 4 to 18 carbon atoms. You may have an atom, a hydroxy group, a C1-C12 alkoxy group, a C6-C18 aromatic hydrocarbon group, a C2-C4 acyl group, or a glycidyloxy group.
v2, w2 and x2 each independently represent an integer of 0 to 5 (preferably 0 or 1).
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.
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 a group.

The alkyl group of R ^{b19 to} R ^b21 preferably has 1 to 12 carbon atoms, and the hydrogen atom contained in the alkyl group is a hydroxy group, an alkoxy group having 1 to 12 carbon atoms or an aromatic group having 6 to 18 carbon atoms. It may be substituted with a hydrocarbon group.
The alicyclic hydrocarbon group of R ^{b19 to} R ^b21 preferably has a carbon number of 4 to 18, and the hydrogen atom contained in the alicyclic hydrocarbon group is a halogen atom or an acyl group of 2 to 4 carbon atoms. Alternatively, it may be substituted with a glycidyloxy group.
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.

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

As mentioned above, although salt (I) was divided into the sulfonate anion and organic cation which comprise it, the said salt (I) is a combination of a sulfonate anion and an organic cation. These sulfonate anions and organic cations can be arbitrarily combined.
Specific examples of this combination include those listed in Tables 1 to 8.

From Tables 1 to 8, the more preferable salt (I) among the salts (I) shown by the combination of the sulfonate anion and the organic cation is specifically shown as follows.

（式中、全ての符号は、それぞれ前記と同じ意味を表す。）
塩基触媒としては、トリエチルアミンなどが挙げられる。
溶媒としては、クロロホルムなどが挙げられる。
式（Ｉ１−ａ）で表される化合物は、例えば、特開２００６−２５７０７８号公報に記載された方法で製造することができる。 Subsequently, ^{L 1} has the formula a group represented by ^(L 1 -A), and, salts for ^{X 1} is a single bond (I) [salt represented by formula (I1) (I) Hereinafter, it is sometimes referred to as “salt (I1)”. ], An embodiment of the method for producing the salt (I) will be described. This salt (I1) is produced, for example, by reacting a compound represented by the formula (I1-a) with a compound represented by the formula (I1-b) in a solvent under a base catalyst. Can do. This reaction is shown in the form of a reaction formula as follows.

(In the formula, all symbols have the same meaning as described above.)
Examples of the base catalyst include triethylamine.
Examples of the solvent include chloroform.
The compound represented by the formula (I1-a) can be produced, for example, by the method described in JP-A-2006-257078.

What is necessary is just to prepare what can be obtained from a market according to a desired structure, and to manufacture the compound represented by a formula (I1-b) with a well-known manufacturing method. Examples of what can be obtained from the market include compounds represented by the following.

（式中、全ての符号は、それぞれ前記と同義である。）
この反応の溶媒としては、アセトニトリルなどが用いられる。
式（Ｉ２−ａ）で表される化合物は、例えば、特開２００７−１４５８２２号公報に記載された方法で製造することができる。 Subsequently, L ¹ is * —CO—O— (CH ₂ ) ₂ —O—CO—CH ₂ — (* represents a bond with a carbon atom bonded to Q ¹ and Q ² ). And salt (I) when X ¹ is —NH— [salt (I) represented by formula (I2), hereinafter sometimes referred to as “salt (I2)”. ], An embodiment of the method for producing the salt (I) will be described. This salt (I2) can be produced, for example, by reacting a compound represented by the formula (I2-a) with a compound represented by the formula (I2-b) in a solvent. This reaction is shown in the form of a reaction formula as follows.

(Wherein all symbols are as defined above)
As a solvent for this reaction, acetonitrile or the like is used.
The compound represented by the formula (I2-a) can be produced, for example, by the method described in JP-A No. 2007-145822.

この反応の溶媒としては、アセトニトリルなどが用いられる。 The compound represented by the formula (I2-b) 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. it can. This reaction is shown in the form of a reaction formula as follows.

As a solvent for this reaction, acetonitrile or the like is used.

この反応の塩基触媒としては、トリエチルアミンなどが用いられる。
この反応の溶媒としては、テトラヒドロフランなどが用いられる。
アルカリ処理のアルカリとしては、水酸化ナトリウムなどが用いられる。 The compound represented by the formula (I2-c) was obtained by reacting the compound represented by the formula (I2-e) with the compound represented by the formula (I2-f) in a solvent under a base catalyst. Thereafter, it can be obtained by alkali treatment. This reaction is shown in the form of a reaction formula as follows.

Triethylamine or the like is used as a base catalyst for this reaction.
Tetrahydrofuran or the like is used as a solvent for this reaction.
Sodium hydroxide or the like is used as the alkali for the alkali treatment.

The compound represented by the formula (I2-f) may be prepared from a market according to a desired structure, or may be produced by a known production method. Examples of what can be obtained from the market include compounds represented by the following.

（式中、全ての符号は、それぞれ前記と同義である。）
この反応の溶媒としては、アセトニトリルなどが用いられる。 Subsequently, L ¹ is * —CO—O—L ^b2 — (* represents a bond with a carbon atom bonded to Q ¹ and Q ² ), and X ¹ is a single bond. Salt (I) in the case [Salt (I) represented by the formula (I3), hereinafter sometimes referred to as “salt (I3)”. ], An embodiment of the method for producing the salt (I) will be described. This salt (I3) can be produced, for example, by reacting a compound represented by the formula (I3-a) with a compound represented by the formula (I3-b) in a solvent. This reaction is shown in the form of a reaction formula as follows.

(Wherein all symbols are as defined above)
As a solvent for this reaction, acetonitrile or the like is used.

この反応の溶媒としては、アセトニトリルなどが用いられる。式（Ｉ３−ｃ）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 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. it can. This reaction is shown in the form of a reaction formula as follows.

As a solvent for this reaction, acetonitrile or the like is used. The compound represented by the formula (I3-c) can be produced, for example, by the method described in JP-A-2008-13551.

What is necessary is just to prepare what can be obtained from a market according to a desired structure, and to manufacture the compound represented by a formula (I3-b) with a well-known manufacturing method. Examples of what can be obtained from the market include compounds represented by the following.

<Acid generator other than salt (I)>
The present resist composition is characterized by containing one or more salts (I) as an acid generator, and the present resist composition is a known acid other than the salt (I) as an acid generator. It may further contain a generator. The acid generator other than the salt (I) may be an ionic acid generator or a nonionic generator, but is preferably an ionic acid generator. The ionic acid generator constitutes the salt (I) with the same cation as the organic cation constituting the salt (I), as well as the cation and anion constituting the ionic acid generator are different from the salt (I). An ionic acid generator composed of a combination with a known anion other than the sulfonate anion may be used.
Hereinafter, the acid generator other than the salt (I) contained in the resist composition is sometimes referred to as “acid generator (B)”.

As an acid generator (B), what is represented by either of Formula (B1-1)-Formula (B1-20) is mentioned, for example. Among them, those containing a triphenylsulfonium cation and a tolylsulfonium cation are preferable. Formula (B1-1), Formula (B1-2), Formula (B1-3), Formula (B1-6), and Formula (B1-7) And salts represented by formula (B1-11), formula (B1-12), formula (B1-13) and formula (B1-14), respectively.

<Resin (A)>
As described above, the resin (A) is insoluble or hardly soluble in an alkaline aqueous solution and has a characteristic that it becomes soluble in an alkaline aqueous solution by the action of an acid (hereinafter, sometimes referred to as “acidic action characteristic”). Note that “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) having acid action characteristics has an acid labile group (hereinafter, sometimes referred to as “acid labile group”) in its molecule. Such a resin (A) is a monomer having an acid labile group (hereinafter, this monomer is sometimes referred to as “monomer (a1)”, and the structural unit derived from the monomer (a1) is referred to as “structural unit (a1)”. Can be produced by polymerization.
In producing the resin (A) having acid action characteristics, the monomer (a1) may be used alone, or two or more kinds may be used in combination.

［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。］ <Acid labile group>
The “acid labile group” means a group that has a leaving group, and the leaving group is removed by 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) (acid labile group (1)) and a group represented by the formula (2) (acid labile group (2)). .

[In Formula (1),
R ^{a1 to} R ^a3 each independently represents an alkyl group having 1 to 8 carbon atoms or an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R ^a1 and R ^a2 are bonded to each other to form 2 to 2 carbon atoms. 20 divalent hydrocarbon groups are formed. * Represents a bond. ]

［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１価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する。該１価の炭化水素基及び該２価の炭化水素基を構成するメチレン基は、酸素原子又は硫黄原子に置き換わってもよい。＊は結合手を表す。］

[In Formula (2),
R ^{a1 ′} and R ^{a2 ′} each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, and R ^{a3 ′} represents a hydrocarbon group having 1 to 20 carbon atoms, or R ^{a3 ′ a2 ′} and R ^{a3 ′} combine with each other to form a divalent hydrocarbon group having 2 to 20 carbon atoms. The monovalent hydrocarbon group and the methylene group constituting the divalent hydrocarbon group may be replaced with an oxygen atom or a sulfur atom. * Represents a bond. ]

The alkyl groups and alicyclic hydrocarbon groups represented by R ^{a1 to} R ^a3 of the acid labile group (1) include those already exemplified in each carbon number range. However, carbon number of this alicyclic hydrocarbon group becomes like this. Preferably it is the range of 3-16.

When R ^a1 and R ^a2 are bonded to each other to form a divalent hydrocarbon group, the group represented by —C (R ^a1 ) (R ^a2 ) (R ^a3 ) is any of the following groups: This is the case. The carbon number of the divalent hydrocarbon group is preferably in the range of 3-12.

Examples of the acid labile group (1) include a 1,1-dialkylalkoxycarbonyl group (in the formula (1), groups in which R ^{a1 to} R ^a3 are alkyl groups, preferably tert-butyl groups), 2-alkyl An adamantane-2-yloxycarbonyl group (in formula (1), R ^a1 and R ^a2 combine to form an adamantyl ring, 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 R ^{a1 ′} and R ^{a2 ′} hydrocarbon groups of the acid labile group (2) include an alkyl group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Among these groups, the same groups are included in the range having 20 or less carbon atoms. However, at least one of R ^{a1 ′} and R ^{a2 ′} is preferably a hydrogen atom.

Specific examples of the acid labile group (2) include the following groups.

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

  Among them, the monomer (a1) having an acid labile group (1) and / or an acid labile group (2) is preferable, and having an acid labile group (1) and / or an acid labile group (2) (meta ) Acrylic monomers are particularly preferred.

  Of the (meth) acrylic monomers having an acid labile group, the monomer (a1) having an alicyclic hydrocarbon group having 5 to 20 carbon atoms is preferred. Since the resin (A) obtained using such a monomer (a1) has a bulky structure such as an alicyclic hydrocarbon group, the resist composition containing the resin (A) The resolution tends to be better.

［式（ａ１−１）中、
Ｌ^a1は、酸素原子又は＊−Ｏ−（ＣＨ₂）_k1−ＣＯ−Ｏ−（ｋ１は１〜７の整数を表し、＊はカルボニル基との結合手を表す。）で表される基を表す。
Ｒ^a4は、水素原子又はメチル基を表す。
Ｒ^a6は、炭素数１〜１０の脂肪族炭化水素基を表す。
ｍ１は０〜１４の整数を表す。
式（ａ１−２）中、
Ｌ^a2は、酸素原子又は＊−Ｏ−（ＣＨ₂）_k1−ＣＯ−Ｏ−（ｋ１は前記と同義である。
）で表される基を表す。
Ｒ^a5は、水素原子又はメチル基を表す。
Ｒ^a7は、炭素数１〜１０の脂肪族炭化水素基を表す。
ｎ１は０〜１０の整数を表す。
ｎ１’は０〜３の整数を表す。］ <Preferred structural unit (a1)>
The resin (A) having a suitable structural unit (a1) obtained by using the monomer (a1) having such an alicyclic hydrocarbon group will be further described in detail. Among the resins (A), a structural unit represented by the formula (a1-1) (hereinafter sometimes referred to as “structural unit (a1-1)”) or a structural unit represented by the formula (a1-2) A resin (A) having (hereinafter referred to as “structural unit (a1-2)” in some cases) is preferable. Such resin (A) may have the structural unit (a1-1) as a single species, may have a plurality of types, or may have the structural unit (a1-2) as a single species. In addition, a plurality of types may be included, and the structural unit (a1-1) and the structural unit (a1-2) may be combined.

[In the formula (a1-1),
L ^a1 represents an oxygen atom or a group represented by * —O— (CH ₂ ) _k1 —CO—O— (k1 represents an integer of 1 to 7, and * represents a bond to a carbonyl group). Represent.
R ^a4 represents a hydrogen atom or a methyl group.
R ^a6 represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms.
m1 represents the integer of 0-14.
In formula (a1-2),
L ^a2 is an oxygen atom or * —O— (CH ₂ ) _k1 —CO—O— (k1 is as defined above).
) Represents a group represented by
R ^a5 represents a hydrogen atom or a methyl group.
R ^a7 represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms.
n1 represents an integer of 0 to 10.
n1 ′ represents an integer of 0 to 3. ]

L ^a1 and L ^a2 are preferably —O— or * —O— (CH ₂ ) _k1 —CO—O—, and L ^a1 and L ^a2 are preferably oxygen atoms or k1 is 1 to 4 A group represented by * —O— (CH ₂ ) _k1 —CO—O—, more preferably an oxygen atom or * —O—CH ₂ —CO—O—, still more preferably oxygen. Is an atom.
R ^a4 and R ^a5 are preferably methyl groups.
Of the aliphatic hydrocarbon groups of R ^a6 and R ^a7 , preferably an alkyl group having 1 to 8 carbon atoms or an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and within the range of the upper limit of the carbon number, Includes the same as those already exemplified. The aliphatic hydrocarbon groups for R ^a6 and R ^a7 are each independently preferably an alkyl group having 8 or less carbon atoms or an alicyclic hydrocarbon group having 8 or less carbon atoms, more preferably an alkyl group having 6 or less carbon atoms. Or it is an alicyclic hydrocarbon group having 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.
n1 ′ is preferably 0 or 1.

  As the structural unit (a1-1), structural units represented by any of the following formulas (a1-1-1) to (a1-1-8) are preferable, and the structural units (a1-1-1) to (a1-1-1) The structural unit represented by any of (a1-1-4) is more preferred, and the structural unit represented by formula (a1-1-2) or (a1-1-3) is more preferred.

［式（ａ１−１´）中、
Ｌ^a1は、酸素原子を表す。
Ｒ^a4は、水素原子又はメチル基を表す。
Ｒ^a6´は、炭素数２又は３のアルキル基を表す。
ｍ１は０〜１４の整数を表す。］ That is, as the structural unit (a1-1), a structural unit represented by the formula (a1-1 ′) is particularly preferable.

[In the formula (a1-1 ′),
L ^a1 represents an oxygen atom.
R ^a4 represents a hydrogen atom or a methyl group.
R ^a6 ′ represents an alkyl group having 2 or 3 carbon atoms.
m1 represents the integer of 0-14. ]

  Examples of the monomer (a1) from which these structural units (a1-1) can be derived include those described in JP-A No. 2010-204646.

On the other hand, as the structural unit (a1-2), a structural unit represented by any of the following formulas (a1-2-1) to (a1-2-12) is preferable. Among these, the structural unit represented by any one of formulas (a1-2-1) to (a1-2-4), formula (a1-2-9) and formula (a1-2-10) is more The structural unit represented by the formula (a1-2-3) or (a1-2-9) is more preferable.

  Examples of the monomer (a1) capable of deriving the structural unit (a1-2) include 1-ethylcyclopentan-1-yl (meth) acrylate, 1-ethylcyclohexane-1-yl (meth) acrylate, and 1-ethyl. Examples include cycloheptan-1-yl (meth) acrylate, 1-methylcyclopentan-1-yl (meth) acrylate, and 1-isopropylcyclopentan-1-yl (meth) acrylate.

  When the resin (A) has the structural unit (a1-1) and / or the structural unit (a1-2), the total content thereof is based on the total structural unit (100 mol%) of the resin (A). The range of 10-95 mol% is preferable, the range of 15-90 mol% is more preferable, the range of 20-85 mol% is further more preferable, and the range of 20-60 mol% is still more preferable. When the structural unit (a1) has a structural unit (a1) having an adamantyl group (particularly preferably, the structural unit (a1-1)), the total of the structural units (a1) in the resin (A) The structural unit (a1) having an adamantyl group is preferably 15 mol% or more with respect to (100 mol%). With such a content ratio, the resin (A) having the structural unit (a1) having an adamantyl group tends to have good dry etching resistance of a resist pattern produced from the resist composition containing the resin (A). There is. In addition, in order to make the total content rate of a structural unit (a1-1) and / or a structural unit (a1-2) into the above-mentioned range, when manufacturing resin (A), it is with respect to the usage-amount of all monomers. What is necessary is just to adjust the usage-amount of the monomer which induces | guides | derives a structural unit (a1-1) and / or a structural unit (a1-2).

  Among the structural units of the resin (A), the structural unit (a1-1) and the structural unit (a1-2) that are preferable for the resin (A) to have acid action characteristics are described in detail. It is particularly preferable that the resin (A) has the unit (a1-1).

  The resin (A) may have a structural unit (a1) other than the structural unit (a1-1) and the structural unit (a1-2) which are suitable structural units (a1). Hereinafter, the structural unit (a1) other than the structural unit (a1-1) and the structural unit (a1-2) will be described by showing a monomer (a1) that derives the structural unit (a1).

［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−ＣＯＯＲ^a13で表される基を表し、Ｒ^a13は、炭素数１〜８の脂肪族炭化水素基を表し、該脂肪族炭化水素基に含まれる水素原子はヒドロキシ基などで置換されていてもよく、該脂肪族炭化水素基を構成するメチレン基は、酸素原子又はカルボニル基に置き換わっていてもよい。Ｒ^a10、Ｒ^a11及びＲ^a12は、それぞれ独立に、炭素数１〜１２の脂肪族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る。該脂肪族炭化水素基及に含まれる水素原子はヒドロキシ基などで置換されていてもよく、該脂肪族炭化水素基を構成するメチレン基は、酸素原子又はカルボニル基に置き換わっていてもよい。］ The resin (A) may have a structural unit (a1) derived from a monomer represented by the following formula (a1-3) (hereinafter sometimes referred to as “monomer (a1-3)”). . Since the resin (A) having the structural unit (a1) derived from the monomer (a1-3) contains a rigid norbornane ring in its main chain, the present resist containing such a resin (A) The composition tends to produce a resist pattern having excellent dry etching resistance.

[In the 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 represented by —COOR ^a13. , R ^a13 represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms, and a hydrogen atom contained in the aliphatic hydrocarbon group may be substituted with a hydroxy group or the like, and constitutes the aliphatic hydrocarbon group The methylene group may be replaced by an oxygen atom or a carbonyl group. R ^a10 , R ^a11 and R ^a12 each independently represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, or R ^a10 and R ^a11 are bonded to each other to form a ring. The hydrogen atom contained in the aliphatic hydrocarbon group may be substituted with a hydroxy group or the like, and the methylene group constituting the aliphatic hydrocarbon group may be replaced with an oxygen atom or a carbonyl group. ]

The aliphatic hydrocarbon group which may have a substituent of R ^a9 is typically an alkyl group which may have a substituent, and among these alkyl groups, an alkyl having no substituent The group includes those already exemplified in the range of 1 to 8 carbon atoms. Examples of the substituent, particularly the aliphatic hydrocarbon group (alkyl group) having a hydroxy group include 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.

The aliphatic hydrocarbon groups of R ^{a10 to} R ^a12 are also typically alkyl groups, and specific examples thereof are the same as those of R ^a9 . The ring formed by combining R ^a10 and R ^a11 together with the carbon atom to which they are bonded includes a cyclohexane ring and an adamantane ring.

As a monomer (a1-3), what was described in Unexamined-Japanese-Patent No. 2010-204646 is used, for example. Among these, a monomer represented by any of the following formula (a1-3-1), formula (a1-3-2), formula (a1-3-3) and formula (a1-3-4) The monomer represented by formula (a1-3-2) or (a1-3-4) is more preferred, and the monomer represented by formula (a1-3-2) is more preferred.

  When the resin (A) has a structural unit derived from the monomer (a1-3), the content is preferably in the range of 10 to 95 mol% with respect to the total structural unit of the resin (A). The range of 90 mol% is more preferable, and the range of 20 to 85 mol% is more preferable.

［式（ａ１−４）中、
Ｒ¹⁰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^ａは０〜４の整数を表す。
Ｒ¹¹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し、ｌ^ａが２以上である場合、複数のＲ¹¹は互いに同一であっても異なってもよい。
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、置換基を有していてもよい炭素数１〜１７の脂肪族炭化水素基又は単結合を表し、該脂肪族炭化水素基を構成するメチレン基は、酸素原子、硫黄原子、カルボニル基、スルホニル基又は−Ｎ（Ｒ^ｃ）−（ただし、Ｒ^ｃは、水素原子又は炭素数１〜６のアルキル基を表す）で表される基に置き換わっていてもよい。
Ｙ^a3は、置換基を有していてもよい炭素数１〜１８の炭化水素基を表す。］ The resin (A) may have a structural unit (a1) derived from a monomer represented by the following formula (a1-4) (hereinafter sometimes referred to as “monomer (a1-4)”).

[In the formula (a1-4),
R ¹⁰ represents an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, a hydrogen atom or a halogen atom.
l ^a represents an integer of 0 to 4;
R ¹¹ 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. In the case where l ^a is 2 or more, a plurality of R ¹¹ may be the same as or different from each other.
R ¹² and R ¹³ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms.
X ^a2 represents an ^optionally substituted aliphatic hydrocarbon group having 1 to 17 carbon atoms or a single bond, and the methylene group constituting the aliphatic hydrocarbon group includes an oxygen atom, a sulfur atom, a carbonyl A group, a sulfonyl group, or a group represented by —N (R ^c ) — (wherein R ^c represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) may be substituted.
Y ^a3 represents an ^optionally substituted hydrocarbon group having 1 to 18 carbon atoms. ]

Among “an alkyl group having 1 to 6 carbon atoms which may have a halogen atom”, the alkyl group includes those already exemplified in the range of 1 to 6 carbon atoms. As the alkyl group having a halogen atom, an alkyl group having a fluorine atom is preferable. For example, a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group. Group, perfluoropentyl group, perfluorohexyl group and the like. Among these, as R < ¹⁰ >, a C1-C4 alkyl group is preferable, a methyl group and an ethyl group are more preferable, and a methyl group is especially preferable.
The alkoxy group of R ¹¹ includes those already exemplified in the range of 1 to 6 carbon atoms. Among them, an alkoxy group having 1 to 4 carbon atoms is preferable, a methoxy group and an ethoxy group are more preferable, and a methoxy group is particularly preferable. preferable.
The acyl group and acyloxy group of R ¹¹ include those already exemplified in the range of 2 to 4 carbon atoms.
The hydrocarbon groups of R ¹² and R ¹³ are those having 1 to 12 carbon atoms, and the hydrocarbon group of Y ^a3 is the aliphatic hydrocarbon group exemplified above in the range of 1 to 18 carbon atoms. Contains any of the aromatic hydrocarbon groups.
The aliphatic hydrocarbon group of X ^a2 is a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, or a divalent group in which a chain hydrocarbon group and an alicyclic hydrocarbon group are combined. And groups obtained by appropriately combining the groups already exemplified in the range of 1 to 17 carbon atoms.

As a monomer (a1-4), the monomer described in Unexamined-Japanese-Patent No. 2010-204646 is mentioned, for example. Among them, any monomer represented by any of the following formulas (a1-4-1) to (a1-4-7) is preferable, and the formulas (a1-4-1) to (a1-4-) The monomer represented by 5) is more preferable.

  When the resin (A) has a structural unit derived from the monomer (a1-4), the content is preferably in the range of 10 to 95 mol% with respect to the total structural unit of the resin (A). The range of mol% is more preferable, and the range of 20 to 85 mol% is particularly preferable.

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、酸素原子、硫黄原子又は＊−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、酸素原子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) (hereinafter sometimes 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 oxygen atom, a sulfur atom, 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 oxygen atom 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 structural unit>
Resin (A) is a structural unit having no acid labile group in addition to the structural unit (a1) containing an acid labile group (hereinafter referred to as “acid stable structural unit” in some cases). Preferably, the derivatizable monomer is referred to as an “acid-stable monomer”. In the resin (A), the acid stable structural unit may have only one type or may have a plurality of types.

  When the resin (A) has an acid stable structural unit, the content ratio of the acid stable structural unit may be determined based on the content ratio of the structural unit (a1). The ratio of the content ratio of the structural unit (a1) and the content ratio of the acid-stable structural unit is represented by [structural unit (a1)] / [acid-stable structural unit], and preferably 10 to 80 mol% / 90 to It is 20 mol%, More preferably, it is 20-60 mol% / 80-40 mol%. If it does in this way, there exists a tendency for the dry etching tolerance of the resist pattern obtained from this resist composition containing resin (A) to become still better.

Next, a preferable thing is demonstrated among an acid stable structural unit.
The acid stable structural unit is preferably a structural unit having a hydroxy group or a lactone ring. An acid stable structural unit having a hydroxy group (hereinafter, sometimes referred to as “acid stable structural unit (a2)”.
) And / or an acid-stable structural unit having a lactone ring (hereinafter, sometimes referred to as “acid-stable structural unit (a3)”) is used as the resist composition containing the resin (A). When applied to a substrate, a coating film formed on the substrate or a composition layer obtained from the coating film is excellent in adhesion to the substrate, so that a resist pattern can be produced with good resolution. In addition, the manufacturing method of the resist pattern using this resist composition here is mentioned later. First, the acid stable structural unit (a2) and the acid stable structural unit (a3) suitable as the acid stable structural unit will be described with specific examples.

<Acid stable structural unit (a2)>
When the acid-stable structural unit (a2) is introduced into the resin (A), a suitable acid-stable structure is used depending on the type of exposure source when producing a resist pattern from the resist composition containing the resin (A). The unit (a2) can be selected. That is, when this resist composition is used for exposure using a KrF excimer laser (wavelength: 248 nm) as an exposure source, or exposure using a high energy beam such as an electron beam or EUV light as an exposure source, an acid stable structural unit ( As a2), it is preferable to introduce an acid stable structural unit (a2-0) having a phenolic hydroxy group into the resin (A).
When using exposure using a short wavelength ArF excimer laser (wavelength: 193 nm) as an exposure source, an acid stable structural unit represented by the formula (a2-1) described later is used as a resin ( It is preferable to introduce into A). Thus, each of the acid stable structural units (a2) possessed by the resin (A) can be selected according to the exposure source used for producing the resist pattern, but the acid stable structural units possessed by the resin (A) ( a2) may have only one type of acid stable structural unit (a2) suitable for the type of exposure source, and two or more types of acid stable structural unit (a2) suitable for the type of exposure source. Or an acid stable structural unit (a2) suitable for the type of exposure source and a combination of other acid stable structural units (a2).

式（ａ２−１）中、
Ｌ^a3は、酸素原子又は＊−Ｏ−（ＣＨ₂）_k2−ＣＯ−Ｏ−（ｋ２は１〜７の整数を表し、＊はカルボニル基（−ＣＯ−）との結合手を表す。）で表される基を表す。
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。 One specific example of the acid stable structural unit (a2) is one represented by the following formula (a2-1) (hereinafter sometimes referred to as “acid stable structural unit (a2-1)”).

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

L ^a3 is preferably an oxygen atom or a group represented by * —O— (CH ₂ ) _k2 —CO—O—, wherein k2 is an integer of 1 to 4, and more preferably an oxygen atom or * —O—CH ₂ —CO—O—, and more preferably an oxygen atom.
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 structural unit (a2-1), the following are mentioned, for example.

  As described above, the exemplified acid stable structural unit (a2-1) is derived from, for example, an acid stable monomer described in JP 2010-204646 A. Among these, the acid stable structural unit represented by any one of formula (a2-1-1), formula (a2-1-2), formula (a2-1-3) and formula (a2-1-4) Are more preferable, and an acid stable structural unit represented by the formula (a2-1-1) or (a2-1-3) is more preferable.

  When the resin (A) has an acid stable structural unit (a2-1), the content ratio is preferably in the range of 3 to 45 mol% with respect to the total structural unit (100 mol%) of the resin (A). The range of 5-40 mol% is more preferable, and the range of 5-35 mol% is more preferable.

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、アクリロイルオキシ基又はメタクリロイルオキシ基を表す。
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の全部又は一部は同じであってもよ。 Next, the acid stable structural unit which has a phenolic hydroxy group among the acid stable structural units which have a hydroxy group is demonstrated. The acid stable structural unit is preferably one represented by the following formula (a2-0) (hereinafter sometimes referred to as “acid stable structural unit (a2-0)”).

In 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 acryloyloxy group, or Represents a methacryloyloxy group.
ma represents an integer of 0 to 4. When ma is an integer of 2 or more, all or some of the plurality of R ^a31 may be the same.

Specific examples of the “alkyl group having 1 to 6 carbon atoms” in the “alkyl group having 1 to 6 carbon atoms which may have a halogen atom” for R ^a30 include those already exemplified in this range. . The “C 1-6 alkyl group having a halogen atom” is one in which at least a part of the hydrogen atoms contained in the C 1-6 alkyl group is substituted with a halogen atom. The specific example of the halogen atom is as already described. Among these, R ^a30 is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group and an ethyl group, and further preferably a methyl group.
Specific examples of the alkoxy group of R ^a31 include those already exemplified in the range of 1 to 6 carbon atoms. Among these, R ^a31 is preferably an alkoxy group having 1 to 4 carbon atoms, more preferably a methoxy group and an ethoxy group, and further preferably a methoxy group.
ma is preferably 0, 1 or 2, more preferably 0 or 1, and still more preferably 0.
ma is preferably 0, 1 or 2, more preferably 0 or 1, and still more preferably 0.

Among the acid stable structural units (a2-0), the following formulas (a2-0-1), (a2-0-2), (a2-0-3) and (a2-0-4) Those represented by either are preferred.
An acid stable monomer capable of deriving such a structural unit is described in, for example, JP 2010-204634 A.

  Acid-stable monomer capable of deriving acid-stable structural unit (a2-0) such as p-hydroxystyrene and p-hydroxy-α-methylstyrene [hereinafter referred to as “acid-stable monomer (a2)” in some cases. ] In the production of the resin (A), the acid stable structural unit (a2-0) represented by the formula (a2-0-1) or the formula (a2-0-2) is converted into the resin (A). After the phenolic hydroxy group in the acid stable monomer (a2) is protected with a protecting group such as an acetyl group to form a protected acid stable monomer (a2), the protected acid Resin (A) can also be manufactured using a stable monomer (a2). A resin (A) having an acid-stable structural unit (a2-0) can be produced by deprotecting a resin having a structural unit derived from the protected acid-stable monomer (a2) and removing the protecting group. . However, when carrying out the deprotection treatment, it is necessary to carry out the deprotection treatment without significantly damaging the other structural unit (a1).

  When the resin (A) has an acid stable structural unit (a2-0), the content ratio is preferably in the range of 5 to 90 mol% with respect to the total structural unit (100 mol%) of the resin (A). The range of 10-85 mol% is more preferable, and the range of 15-80 mol% is further more preferable.

<Acid stable structural unit (a3)>
The lactone ring possessed by the acid stable structural unit (a3) may be monocyclic such as β-propiolactone ring, γ-butyrolactone ring and δ-valerolactone ring, monocyclic lactone ring and other rings. Or a condensed ring. Among these lactone rings, a γ-butyrolactone ring and a condensed ring of a γ-butyrolactone ring and another ring are preferable.

［式（ａ３−１）中、
Ｌ^a4は、酸素原子又は＊−Ｏ−（ＣＨ₂）_k3−ＣＯ−Ｏ−（ｋ３は１〜７の整数を表す。）で表される基を表す。＊はカルボニル基との結合手を表す。
Ｒ^a18は、水素原子又はメチル基を表す。
ｐ１は０〜５の整数を表す。
Ｒ^a21は炭素数１〜４の脂肪族炭化水素基を表し、ｐ１が２以上の場合、複数のＲ^a21の全部又は一部は同じであってもよい。
式（ａ３−２）中、
Ｌ^a5は、酸素原子又は＊−Ｏ−（ＣＨ₂）_k3−ＣＯ−Ｏ−（ｋ３は１〜７の整数を表す。）で表される基を表す。＊はカルボニル基との結合手を表す。
ｑ１は、０〜３の整数を表す。
Ｒ^a22は、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し、ｑ１が２以上の場合、複数のＲ^a22の全部又は一部は同じであってもよい。
式（ａ３−３）中、
Ｌ^a6は、酸素原子又は＊−Ｏ−（ＣＨ₂）_k3−ＣＯ−Ｏ−（ｋ３は１〜７の整数を表す。）で表される基を表す。＊はカルボニル基との結合手を表す。
Ｒ^a20は、水素原子又はメチル基を表す。
ｒ１は、０〜３の整数を表す。
Ｒ^a23は、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し、ｒ１が２以上の場合、複数のＲ^a23の全部又は一部は同じであってもよい。］ The acid stable structural unit (a3) is preferably one represented by the following formula (a3-1), formula (a3-2) or formula (a3-3). Resin (A) may have only 1 type among these, and may have 2 or more types. In the following description, what is represented by formula (a3-1) may be referred to as “acid-stable structural unit (a3-1)”, and what is represented by formula (a3-2) is “acid In some cases, it is referred to as “stable structural unit (a3-2)”, and what is represented by the formula (a3-3) may be referred to as “acid stable structural unit (a3-3)”.

[In the formula (a3-1),
L ^a4 represents an oxygen atom or a group represented by * —O— (CH ₂ ) _k3 —CO—O— (k3 represents an integer of 1 to 7). * Represents a bond with a carbonyl group.
R ^a18 represents a hydrogen atom or a methyl group.
p1 represents an integer of 0 to 5.
R ^a21 represents an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and when p1 is 2 or more, all or some of the plurality of R ^a21 may be the same.
In formula (a3-2),
L ^a5 represents an oxygen atom or a group represented by * —O— (CH ₂ ) _k3 —CO—O— (k3 represents an integer of 1 to 7). * Represents a bond with a carbonyl group.
q1 represents an integer of 0 to 3.
R ^a22 represents a carboxy group, a cyano group, or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and when q1 is 2 or more, all or some of the plurality of R ^a22 may be the same.
In formula (a3-3),
L ^a6 represents an oxygen atom or a group represented by * —O— (CH ₂ ) _k3 —CO—O— (k3 represents an integer of 1 to 7). * Represents a bond with a carbonyl group.
R ^a20 represents a hydrogen atom or a methyl group.
r1 represents an integer of 0 to 3.
R ^a23 represents a carboxy group, a cyano group, or an aliphatic hydrocarbon group having 1 to 4 carbon atoms. 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), L ^{a4 to} L ^a6 are the same as those described for L ^a3 in formula (a2-1).
L ^{a4 to} L ^a6 are each independently an oxygen atom or a group represented by * —O— (CH ₂ ) _k3 —CO—O— in which k3 is an integer of 1 to 4, preferably an oxygen atom and * —O—CH ₂ —CO—O— is more preferable, and an oxygen atom is more preferable.
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, q1 and r1 are preferably integers of 0 to 2, more preferably 0 or 1. When p1 is 2, two R ^a21 may be the same as or different from each other. When q1 is 2, two R ^a22 may be the same as or different from each other, and r1 is 2. Two R ^a23 may be the same or different from each other.

  Hereinafter, preferred examples of the acid stable structural unit (a3-1), the acid stable structural unit (a3-2), and the acid stable structural unit (a3-3) will be shown.

Preferable examples of the acid stable structural unit (a3-1) include the following formula (a3-1-1), formula (a3-1-2), formula (a3-1-3) and formula (a3-1-4). ).

Preferable examples of the acid stable structural unit (a3-2) include the following formula (a3-2-1), formula (a3-2-2), formula (a3-2-3) and formula (a3-2-4). ).

Preferred examples of the acid stable structural unit (a3-3) include the following formula (a3-3-1), formula (a3-3-2), formula (a3-3-3) and formula (a3-3-4). ).

  The acid stable structural unit (a3-1), the acid stable structural unit (a3-2), and the acid stable structural unit (a3-3) can be derived from an acid stable monomer described in JP 2010-204646 A. Among the specific examples of the acid stable structural unit (a3), the formula (a3-1-1), the formula (a3-1-2), the formula (a3-2-3), or the formula (a3-2-4) Is more preferable, and the acid stable structural unit represented by Formula (a3-1-1) or Formula (a3-2-3) is more preferable.

When the resin (A) has an acid stable structural unit (a3), the total content is preferably in the range of 5 to 70 mol% with respect to all the structural units (100 mol%) of the resin (A). The range of 10 to 65 mol% is more preferable, and the range of 10 to 60 mol% is more preferable.
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 more preferable.

<Other acid stable structural units>
The preferred acid stable structural unit (a2) and acid stable structural unit (a3) have been described as the acid stable structural unit possessed by the resin (A). However, the resin (A) contains the acid stable structural unit (a2) and the acid stable structural unit. It may have an acid stable structural unit other than the structural unit (a3). Here, the acid stable structural unit (a4) other than the acid stable structural unit (a2) and the acid stable structural unit (a3) is referred to. Hereinafter, the acid-stable structural unit (a4) will be described by showing an acid-stable monomer (hereinafter sometimes referred to as “acid-stable monomer (a4)”) from which the acid-stable structural unit (a4) can be derived.

式（ａ４−１）中、
Ｒ^a41は、炭素数１〜１２の１価の脂肪族炭化水素基又は炭素数６〜１２の１価の芳香族炭化水素基を表し、該１価の脂肪族炭化水素基を構成するメチレン基は、酸素原子又はカルボニル基に置き換わっていてもよい。Ａ^a41は、置換基を有していてもよい炭素数１〜６のアルカンジイル基又は式（ａ−ｇ１）

［式（ａ−ｇ１）中、
ｓは０又は１を表す。
Ａ^a42及びＡ^a44は、それぞれ独立に、置換基を有していてもよい炭素数１〜５の脂肪族炭化水素基を表す。
Ａ^a43は、置換基を有していてもよい炭素数１〜５の脂肪族炭化水素基又は単結合を表す。
Ｘ^a41及びＸ^a42は、それぞれ独立に、酸素原子、カルボニル基、カルボニルオキシ基又はオキシカルボニル基を表す。
ただし、Ａ^a42、Ａ^a43、Ａ^a44、Ｘ^a41及びＸ^a42の炭素数の合計は６以下である。］
で表される基を表す。
Ｒ^a42は、置換基を有していてもよい脂肪族炭化水素基を表す。該脂肪族炭化水素基は部分的に、炭素炭素不飽和結合を有していてもよいが、炭素炭素不飽和結合を有さない脂肪族飽和炭化水素基が好ましい。該脂肪族飽和炭化水素基としては、アルキル基（当該アルキル基は直鎖でも分岐していてもよい）及び脂環式炭化水素基、並びに、アルキル基及び脂環式炭化水素基を組み合わせた脂肪族炭化水素基などが挙げられる。 A specific example of the acid stable monomer (a4) is, for example, a monomer represented by the following formula (a4-1) (hereinafter sometimes referred to as “monomer (a4-1)”). As will be described later, this monomer (a4-1) preferably has a fluorine atom.

In formula (a4-1),
R ^a41 represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and a methylene group constituting the monovalent aliphatic hydrocarbon group. May be replaced by an oxygen atom or a carbonyl group. A ^a41 is an alkanediyl group having 1 to 6 carbon atoms which may have a substituent or a formula (a-g1).

[In the formula (a-g1),
s represents 0 or 1.
A ^a42 and A ^a44 each independently represent an ^optionally substituted aliphatic hydrocarbon group having 1 to 5 carbon atoms.
A ^a43 represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms which may have a substituent or a single bond.
X ^a41 and X ^a42 each independently represent an oxygen atom, a carbonyl group, a carbonyloxy group or an oxycarbonyl group.
However, the total number of carbon atoms of A ^a42 , A ^a43 , A ^a44 , X ^a41 and X ^a42 is 6 or less. ]
Represents a group represented by
R ^a42 represents an aliphatic hydrocarbon group which may have a substituent. The aliphatic hydrocarbon group may partially have a carbon-carbon unsaturated bond, but an aliphatic saturated hydrocarbon group having no carbon-carbon unsaturated bond is preferable. Examples of the aliphatic saturated hydrocarbon group include an alkyl group (the alkyl group may be linear or branched), an alicyclic hydrocarbon group, and an aliphatic combination of an alkyl group and an alicyclic hydrocarbon group. Group hydrocarbon group and the like.

^Among the aliphatic hydrocarbon groups ^represented by R ^a41 , the alkyl group and the aromatic hydrocarbon group include those already exemplified in the respective ranges of the carbon number.

［式（ａ−ｇ３）中、
Ｘ^a43は、酸素原子、カルボニル基、カルボニルオキシ基又はオキシカルボニル基を表す。
Ａ^a45は、ハロゲン原子を有していてもよい炭素数３〜１７の脂肪族炭化水素基を表す。］
つまり、Ｒ^a42は、以下の式（ａ−ｇ２）で表される基であることが好ましい。

［式（ａ−ｇ２）中、
Ａ^a46は、ハロゲン原子を有していてもよい炭素数３〜１７の脂肪族炭化水素基を表す。
Ｘ^a44は、カルボニルオキシ基又はオキシカルボニル基を表す。
Ａ^a47は、ハロゲン原子を有していてもよい炭素数３〜１７の脂肪族炭化水素基を表す。
ただし、Ａ^a46、Ａ^a47及びＸ^a44の炭素数の合計は１８以下である。］ Further, the aliphatic hydrocarbon group R ^a42 may not have have a substituent, but when R ^a42 is an aliphatic hydrocarbon group having a substituent group. Such a substituent is preferably a halogen atom or a group represented by the formula (a-g3).

[In the formula (a-g3),
X ^a43 represents an oxygen atom, a carbonyl group, a carbonyloxy group or an oxycarbonyl group.
A ^a45 represents an aliphatic hydrocarbon group having 3 to 17 carbon atoms which may have a halogen atom. ]
That is, R ^a42 is preferably a group represented by the following formula (a-g2).

[In the formula (a-g2),
A ^a46 represents an aliphatic hydrocarbon group having 3 to 17 carbon atoms which may have a halogen atom.
X ^a44 represents a carbonyloxy group or an oxycarbonyl group.
A ^a47 represents an aliphatic hydrocarbon group having 3 to 17 carbon atoms which may have a halogen atom.
However, the total number of carbon atoms of A ^a46 , A ^a47 and X ^a44 is 18 or less. ]

Preferred R ^a42 , an aliphatic hydrocarbon group having a substituent selected from the group consisting of a halogen atom and a group represented by formula (a-g3) (a group represented by formula (a-g2)) Detailed description.

  First, an aliphatic hydrocarbon group having a halogen atom will be described. Such an aliphatic hydrocarbon group is typically an alkyl group having a halogen atom and an alicyclic hydrocarbon group having a halogen atom (preferably a cycloalkyl group having a halogen atom). The alkyl group having a halogen atom is one in which part or all of the hydrogen atoms constituting the alkyl group are substituted with halogen atoms. Similarly, an alicyclic hydrocarbon group having a halogen atom is one in which part or all of the hydrogen atoms constituting the alicyclic hydrocarbon group are substituted with halogen atoms. The halogen atom contained in the alkyl group having a halogen atom and the alicyclic hydrocarbon group having a halogen atom is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, or a combination thereof, but a fluorine atom Is particularly preferred.

When the monomer (a4-1) in which R ^a42 is an aliphatic hydrocarbon group having a fluorine atom is shown as a specific example in the case where A ^a41 is a preferable ethylene group, the following formula (a4-1-1) to And a monomer represented by the formula (a4-1-22).

When R ^a42 is an aliphatic hydrocarbon group having a halogen atom, a perfluoroalkyl group in which all of the hydrogen atoms constituting the alkyl group are substituted with fluorine atoms, or all of the hydrogen atoms constituting the cycloalkyl group are fluorine atoms. A perfluorocycloalkyl group substituted with is more preferable. Among the specific examples described above, the monomer (a4-1) in which R ^a42 is a perfluoroalkyl group or a perfluorocycloalkyl group includes the formula (a4-1-3), the formula (a4-1-4), the formula ( a4-1-7), formula (a4-1-8), formula (a4-1-11), formula (a4-1-12), formula (a4-1-15), formula (a4-1-16) ), Formula (a4-1-19), formula (a4-1-20), formula (a4-1-21), and formula (a4-1-22). Further, R ² is preferably a perfluoroalkyl group, and examples of the perfluoroalkyl group include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a perfluoroheptyl group, and a perfluorooctyl group. Etc. are exemplified. More preferably, it is a C1-C6 perfluoroalkyl group, More preferably, it is a C1-C3 perfluoroalkyl group.

^Next , the ^case where R ^a42 is an aliphatic hydrocarbon group having a group represented by the formula (a-g3) will be described. The aliphatic hydrocarbon group may have one or a plurality of groups represented by the formula (a-g3), but the carbon atom contained in the group represented by the formula (a-g3) The total carbon number of the aliphatic hydrocarbon group including the number of is preferably 15 or less, and more preferably 12 or less. In order to satisfy such a preferable total number of carbon atoms, a group having one group represented by the formula (a-g3) is preferable as R ^a42 .

［式（ａ４−１’）中、すべての符号はいずれも、前記と同義である。］ The monomer (a4-1) in which R ^a42 is an aliphatic hydrocarbon group having one group represented by the formula (a-g2) is specifically represented by the following formula (a4-1 ′). (Hereinafter referred to as “monomer (a4-1 ′)” in some cases).

[In the formula (a4-1 ′), all symbols are as defined above. ]

In the monomer (a4-1 ′), both A ^a46 and A ^a47 may have a halogen atom, but A ^a46 is an aliphatic hydrocarbon group having a halogen atom, or A ^a47 is a halogen atom. The aliphatic hydrocarbon group having Furthermore, A ^a46 is preferably an aliphatic hydrocarbon group having a halogen atom, and among them, A ^a46 is more preferably an alkanediyl group having a fluorine atom, and further preferably a perfluoroalkanediyl group. The “perfluoroalkanediyl group” refers to an alkanediyl group in which all of the hydrogen atoms are substituted with fluorine atoms.

When the compound (a4-1 ′) in which R ^a42 is a perfluoroalkanediyl group is exemplified when A ^a41 is an ethylene group, the following formulas (a4-1′-1) to (a4-1′-22) ) And monomers represented respectively.

A ^a46 and A ^a47 are arbitrarily selected in the range where the total number of carbon atoms is 17 or less, and the carbon number of A ^a46 is preferably in the range of 1-6, more preferably in the range of 1-3.
On the other hand, the carbon number of A ^a47 is preferably in the range of 4-15, more preferably in the range of 5-12. Further preferred A ¹⁴ is an alicyclic hydrocarbon group having 6 to 12 carbon atoms, and as the alicyclic hydrocarbon group, a cyclohexyl group and an adamantyl group are still more preferred.

このような構造を有するモノマー（ａ４−１’）は、前記の具体例の中では、式（ａ４−１’−９）〜式（ａ４−１’−２０）でそれぞれ表される化合物が該当する。 Among the combinations of A ^a46 and A ^a47, the more preferable, * - is represented by the partial structure represented by A ^a46 -X ^a44 -A ^a47 (* represents a bond to a carbonyl group), the following structure Is mentioned.

The monomer (a4-1 ′) having such a structure is a compound represented by the formula (a4-1′-9) to the formula (a4-1′-20) in the above specific examples. To do.

  When the resin (A) has a structural unit derived from the monomer (a4-1), the content ratio is in the range of 1 to 20 mol% with respect to the total structural unit (100 mol%) of the resin (A). Is preferable, the range of 2-15 mol% is more preferable, and the range of 3-10 mol% is further more preferable.

  As described above, the structural unit (a1-1), the structural unit (a1-2), the other structural unit (a1), and the acid stable structural unit suitable as the structural unit (a1) of the resin (A). Although the acid stable structural unit (a2), the acid stable structural unit (a3), and the acid stable structural unit (a4) have been described in detail, the structural unit other than these may be included. Mention may be made of structural units well known in the art.

Moreover, resin which has a structural unit derived from the monomer (a4-1) shown here can also be contained in this resist composition separately from resin (A). In other words, the resin (A) having an acid labile group [structural unit (a1)] in the molecule and the structural unit derived from the monomer (a4-1) having no acid labile group in the molecule. A resin (hereinafter, sometimes referred to as “resin (X)”) may be combined and contained in the resist composition.
In this case, the content ratio of the structural unit derived from the monomer (a4-1) in the resin (X) is preferably 80 mol% or more with respect to all the structural units (100 mol%) of the resin (X). 85 mol% or more is more preferable, and 90 mol% or more is further more preferable.

  In the resist composition, a resin (A) having acid action characteristics and a resin (X) not having acid action characteristics may be used in combination. In this case, as the resin (X), a monomer ( A resin having a structural unit derived from a4-1) can be used. More specifically, the resin (X) preferably has a structural unit derived from the monomer (a4-1 ′) among the structural units derived from the monomer (a4-1). The content ratio of the structural unit derived from the monomer (a4-1) [monomer (a4-1 ′)] with respect to the total structural unit of the resin (X) is, for example, preferably 80 mol% or more, and more preferably 85 mol% or more. 90 mol% or more is more preferable. Resin (X) may consist essentially of a structural unit derived from monomer (a4-1) [monomer (a4-1 ′)]. In addition, as the structural unit that the resin (X) may have other than the structural unit derived from the monomer (a4-1), the above-mentioned acid stable structural unit (a2), acid stable structural unit (a3), and the like Can be mentioned.

  Resin (X) is also preferable if it has a structural unit derived from monomer (a4-1) [monomer (a4-1 ′)], but if it consists of a structural unit that does not have an acid labile group, You may further have a structural unit well-known in this technical field.

<Method for producing resin (A)>
The resin (A) is obtained by copolymerizing the monomer (a1) for deriving the structural unit (a1), more preferably the monomer (a1) and an acid stable monomer, and more preferably the structural unit. (A1-1) and / or monomer (a1) for deriving structural unit (a1-2) and acid-stable monomer for deriving acid-stable structural unit (a2) and / or acid-stable structural unit (a3) Polymerized. For example, when the resist composition is used for EUV exposure, the monomer (a1) that induces the structural unit (a1-1) and / or the structural unit (a1-2), and the acid stable structural unit (a2- And an acid-stable monomer derived from 0).
The resin (A) further preferably has a structural unit (a1-1) having an adamantyl group as the structural unit (a1). The resin (A) can be produced by subjecting the monomer as described above to a known polymerization method (for example, radical polymerization method) and polymerizing (copolymerizing) it.
On the other hand, the resin (X) is preferably obtained by polymerizing the monomer (a4-1) [monomer (a4-1 ′)] by a known polymerization method, and this polymerization [production of resin (X)] In addition to monomer (a4-1) [monomer (a4-1 ′)], other acid-stable monomers [for example, monomers that induce acid-stable structural units (a2) or acid-stable structural units (a3)] These may be copolymerized using these.

The weight average molecular weight of the resin (A) is preferably 2,500 or more (more preferably 3,000 or more) and 50,000 or less (more preferably 30,000 or less). In addition, the weight average molecular weight here is calculated | required as a conversion value of a standard polystyrene reference | standard by gel permeation chromatography analysis. Detailed analysis conditions for this analysis are described in the Examples of the present application.
On the other hand, when the resin (X) is used in the resist composition, the weight average molecular weight of the resin (X) is preferably 8,000 or more (more preferably 10,000 or more), 80,000 or less (more preferably). Is less than 60,000). The means for measuring the weight average molecular weight of the resin (X) is the same as that for the resin (A).

<Basic compound (C)>
This resist composition preferably further contains a basic compound (C). Such a basic compound (C) is what is called a quencher in this technical field. 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 the formula (C1),
R ^c1 , R ^c2 and R ^c3 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alicyclic hydrocarbon group having 5 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms. 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, and the aromatic hydrocarbon group The hydrogen atom contained is substituted with 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. It may be. ]

［式（Ｃ１−１）中、
Ｒ^c2及びＲ^c3は、前記と同義である。
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の全部又は一部は同じであってもよい。］

[In the formula (C1-1),
R ^c2 and R ^c3 are as defined 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, all or some of the plurality of R ^c4 may be the same. ]

［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と同義である。
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の全部又は一部は同じであってもよい。］

[In Formula (C2), Formula (C3) and Formula (C4),
R ^c5 , R ^c6 , R ^c7 and R ^c8 are each independently synonymous with 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, all or some of the plurality of R ^c9 may be the same. ]

［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と同義である。
Ｒ^c14、Ｒ^c15及びＲ^c17は、それぞれ独立に、Ｒ^c4と同義である「。
ｏ３及びｐ３は、それぞれ独立に０〜３の整数を表し、ｏ３が２以上であるとき、複数のＲ^c14の全部又は一部は同じであってもよい。ｐ３が２以上であるとき、複数のＲ^c15の全部又は一部は同じであってもよい。
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 are each independently synonymous with R ^c1 .
R ^c14 , R ^c15 and R ^c17 are each independently synonymous with R ^c4 .
o3 and p3 each independently represent an integer of 0 to 3, and when o3 is 2 or more, all or some of the plurality of R ^c14 may be the same. When p3 is 2 or more, all or some of the plurality of R ^c15 may be the same.
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と同義である。
ｑ３、ｒ３及びｓ３は、それぞれ独立に０〜３の整数を表し、ｑ３が２以上であるとき、複数のＲ^c18の全部又は一部は同じであってもよい。ｒ３が２以上であるとき、複数のＲ^c19の全部又は一部は同じであってもよい。ｓ３が２以上であるとき、複数のＲ^c20の全部又は一部は同じであってもよい。
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。］

[In Formula (C7) and Formula (C8),
R ^c18, R ^c19 and R ^c20 in each occurrence independently has the same meaning as R ^c4.
q3, r3 and s3 each independently represents an integer of 0 to 3, and when q3 is 2 or more, all or some of the plurality of R ^c18 may be the same. When r3 is 2 or more, all or some of the plurality of R ^c19 may be the same. When s3 is 2 or more, all or some of the plurality of R ^c20 may be the same.
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. ]

  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 thereof include diphenylethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, and 4,4′-diamino-3,3′-diethyldiphenylmethane. Propyl aniline, and more preferably include 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 Examples include ammonium hydroxide, tetra-n-butylammonium salicylate, and choline.

<Solvent (D)>
This resist composition preferably further contains a solvent (D). The solvent (D) contained in the resist composition is coated on the substrate in the production of a resist pattern, which will be described later, according to the type and amount of the salt (I) or resin (A). From the standpoint of good coating properties during the process, an optimal one can be selected as appropriate.

  Examples of the solvent (D) 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 Examples thereof include esters such as ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; cyclic esters such as γ-butyrolactone. A solvent (D) may be used individually by 1 type, and may use 2 or more types together.

<Other ingredients>
The resist composition comprises a component other than the acid generator containing the salt (I) and the resin (A) and the solvent (D), acid generator (B), and basic compound (C) used as necessary. You may contain. This component may be referred to as “component (F)”. Examples of the component (F) include additives known in the art, for example, polymer compounds other than the resin (A), sensitizers, dissolution inhibitors, surfactants, stabilizers, and dyes.

<Preparation method of the present resist composition>
The present resist composition can be usually prepared by mixing the salt (I) and the resin (A) in the presence of the solvent (D). Furthermore, you may mix an acid generator (B), a basic compound (C), and / or a component (F) as needed as above-mentioned. It is preferable to mix the basic compound (C). The mixing order is arbitrary and is not particularly limited. The temperature at the time of mixing can select the suitable temperature range from the range of 10-40 degreeC according to the solubility with respect to solvent (D), such as a kind (resin (A)), such as resin (A). An appropriate mixing time can be selected from 0.5 to 24 hours depending on the mixing temperature. The mixing means is not particularly limited, and stirring and mixing can be used.
By selecting the amount of each component used when preparing the resist composition of the present invention, the content of each component in the resist composition of the present invention can be adjusted.

  The content ratio of the acid generator in the resist composition is preferably 40% by mass or less, more preferably 35% by mass or less, and preferably 1% by mass or more, more preferably based on the solid content of the resist composition. Is 3% by mass or more. In addition, solid content here means the sum total of what remove | excluded the solvent (D) from this resist composition. The solid content can be determined by subjecting the resist composition to analysis such as liquid chromatography and gas chromatography.

  The content of the salt (I) is preferably 10 parts by mass or more, more preferably 30 parts by mass or more with respect to 100 parts by mass of the total amount of the acid generator. In the present resist composition, substantially only the salt (I) can be used as an acid generator. As the acid generator other than the salt (I), the acid generator (B) is preferable.

  A preferable range of the content ratio of the resin (A) in the resist composition is determined based on the solid content of the resist composition. Specifically, the resin (A) is preferably 80% by mass or more and 99% by mass or less based on the mass of the solid content. When the resin composition (X) is contained in the resist composition, the content ratio is about 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, based on the content of the resin (A). About 1 to 15% by mass.

  When the basic compound (C) is contained in the resist composition, the content ratio is preferably about 0.01 to 5% by mass with respect to the solid content of the resist composition, more preferably 0.8. It is about 01 to 3% by mass, particularly preferably about 0.01 to 1% by mass.

  The content ratio of the solvent (D) in the present resist composition is 90% by mass or more, preferably 92% by mass or more, more preferably 94% by mass or more, based on the total mass of the present resist composition. 0.9 mass% or less, preferably 99 mass% or less.

  When the resist composition contains the component (F), the appropriate content can be adjusted according to the type of the component (F).

  Thus, each of the acid generator containing the salt (I) and the resin (A), and the solvent (D), the basic compound (C), or the component (F) used as necessary is mixed at a preferable content. Then, it is preferable to filter using a filter having a pore size of about 0.003 to 0.2 μm.

<Method for producing resist pattern>
Specifically showing a method for producing a resist pattern using the present resist composition,
(1) a step of applying the resist composition 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,
Examples include (4) a step of heating the composition layer after exposure, and (5) a step of developing the composition layer after heating. Hereinafter, each of the steps shown here is referred to as “step (1)” to “step (5)”.

  Application of the resist composition on the substrate in the step (1) can be performed by a coating apparatus widely used for applying a resist composition for semiconductor microfabrication, such as a spin coater. Thus, a coating film made of the present resist composition is formed on the substrate. The film thickness of the coating film can be adjusted by variously adjusting the conditions (coating conditions) of the coating apparatus, and by applying an appropriate preliminary experiment, the coating film can be applied to have a desired film thickness. You can choose the conditions. Various substrates to be subjected to microfabrication can be selected as the substrate before applying the resist composition. The substrate can be washed or an antireflection film can be formed before applying the resist composition. For example, a commercially available composition for an organic antireflection film can be used for forming the antireflection film.

In the step (2), the present resist composition coated on the substrate, that is, the coated film is dried to remove the solvent (D). Drying is performed, for example, by evaporating the solvent from the coating film by a heating means using a heating device such as a hot plate (so-called pre-bake), a decompression means using a decompression device, or a combination of these means. Is called. The drying conditions can be selected according to the type of the solvent (D) contained in the resist composition. For example, in the case of a heating means using a hot plate, the surface temperature of the hot plate is set to a range of about 50 to 200 ° C. It is preferable to carry out. In the decompression means, it is preferable to enclose the substrate on which the coating film is formed in an appropriate decompressor, and then set the internal pressure of the decompressor to about 1 to 1.0 × 10 ⁵ Pa. Thus, by removing the solvent (D) from the coating film, a composition layer is formed on the substrate.

Step (3) is a step of exposing the composition layer, and preferably a step of exposing the composition layer using an exposure machine. The exposure is performed through a mask (photomask) on which a desired pattern to be finely processed is formed. As an exposure light source of the exposure machine, an ultraviolet light source such as a KrF excimer laser (wavelength 248 nm), an ArF excimer laser (wavelength 193 nm), an F ₂ excimer laser (wavelength 157 nm), or a solid-state laser light source (YAG In addition, various lasers such as those that emit laser light from a far ultraviolet region or a vacuum ultraviolet region by converting the wavelength of laser light from a semiconductor laser or the like can be used. The exposure machine may be an immersion exposure machine. 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”.
By exposing through a mask, the composition layer has an exposed portion (exposed portion) and an unexposed portion (unexposed portion). In the composition layer of the exposed area, the salt (I) and the acid generator (B) contained in the composition layer generate an acid upon receiving exposure energy, and are further in the resin (A) by the action of the generated acid. Since the acid labile group causes a deprotection reaction, the resin (A) in the composition layer of the exposed area becomes soluble in the alkaline aqueous solution. On the other hand, since the exposure energy is not received in the unexposed area, the resin (A) remains insoluble or hardly soluble in the alkaline aqueous solution. Since the composition layer in the exposed portion and the composition layer in the unexposed portion are significantly different in solubility in an alkaline aqueous solution, a resist pattern can be formed by development with the alkaline aqueous solution.

  In step (4), the composition layer after exposure is subjected to heat treatment (so-called post-exposure baking). Such heat treatment is preferably the heating means using the hot plate shown in the step (2). In addition, when performing the heating means using a hot plate in the step (4), the surface temperature of the hot plate is preferably about 50 to 200 ° C, more preferably about 70 to 150 ° C. The deprotection reaction is promoted by the heat treatment.

Step (5) is a step of developing the heated composition layer, and preferably the heated composition layer is developed with a developing device. In the developing step, when the composition layer after heating is brought into contact with an alkaline aqueous solution, the exposed composition layer is dissolved and removed in the alkaline aqueous solution, and the unexposed composition layer remains on the substrate. A resist pattern is manufactured on the substrate.
As the alkaline aqueous solution, those known in this technical field called “alkaline developer” can be used. Examples of the alkaline aqueous solution include an aqueous solution of tetramethylammonium hydroxide and an aqueous solution of (2-hydroxyethyl) trimethylammonium hydroxide (commonly called choline).

  After the development, it is preferable to perform a rinsing treatment with ultrapure water or the like. Furthermore, it is preferable to remove moisture remaining on the substrate and the resist pattern.

  According to the resist pattern manufacturing method including the steps (1) to (5) as described above, a resist pattern can be manufactured with an excellent focus margin due to the effect of the present resist composition.

<Application>
This resist composition is suitable as 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 for EUV exposure.

Hereinafter, the present invention will be described in detail by way of examples.
In Examples and Comparative Examples, “%” and “part” representing the content and the amount used are based on mass unless otherwise specified.
The weight average molecular weight is a value obtained by gel permeation chromatography (HLC-8120GPC, manufactured by Tosoh Corporation, three columns are “TSKgel Multipore HXL-M”, and the solvent is tetrahydrofuran) using polystyrene as a standard product.
Column: TSKgel Multipore H _XL -M x 3 + guardcolumn (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min
Detector: RI detector Column temperature: 40 ° C
Injection volume: 100 μl
Molecular weight standard: Standard polystyrene (manufactured by Tosoh Corporation)

  The structure of the compound was confirmed by measuring the molecular peak using mass spectrometry (LC is model 1100 manufactured by Agilent, and MASS is LC / MSD manufactured by Agilent). In the following examples, the value of this molecular peak is indicated by “MASS”.

式（Ｉ−１−ａ）で表される化合物１２．００部及びクロロホルム９６．００部を、反応器に仕込み、２３℃で３０分間攪拌した。その後、トリエチルアミン２．９４部を添加した後、式（Ｉ−１−ｂ）で表される化合物５．８４部を仕込み、２３℃程度で３時間攪拌した。得られた反応溶液に、イオン交換水４０部及びクロロホルム３０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。回収された有機層に、イオン交換水４０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０．５０部を加えて攪拌し、ろ過した。得られたろ液を濃縮し、酢酸エチル７０部を加えて攪拌し、ろ過することにより、式（Ｉ−１）で表される塩１１．６３部を得た。これを「Ｉ−１」という。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ２６３．１
ＭＡＳＳ（ＥＳＩ（−）Ｓｐｅｃｔｒｕｍ）：Ｍ⁻ ５６９．２ Example 1 [Synthesis of a salt represented by the formula (I-1)]

12.00 parts of a compound represented by the formula (I-1-a) and 96.00 parts of chloroform were charged into a reactor and stirred at 23 ° C. for 30 minutes. Thereafter, 2.94 parts of triethylamine was added, and then 5.84 parts of the compound represented by the formula (I-1-b) was added, followed by stirring at about 23 ° C. for 3 hours. To the obtained reaction solution, 40 parts of ion-exchanged water and 30 parts of chloroform were added and stirred at 23 ° C. for 30 minutes. Then, it left still and liquid-separated and obtained the organic layer. To the recovered organic layer, 40 parts of ion-exchanged water was 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, 0.50 parts of activated carbon was added, stirred and filtered. The obtained filtrate was concentrated, 70 parts of ethyl acetate was added, stirred, and filtered to obtain 11.63 parts of the salt represented by the formula (I-1). This is referred to as “I-1”.
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (−) Spectrum): M ^- 569.2

式（Ｉ−２９−ａ）で表される化合物１２．８２部及びクロロホルム１０２．５６部を、反応器に仕込み、２３℃で３０分間攪拌した。その後、トリエチルアミン２．９４部を添加した後、式（Ｉ−２９−ｂ）で表される化合物５．８４部を仕込み、２３℃程度で３時間攪拌した。得られた反応溶液に、イオン交換水４０部及びクロロホルム３０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。回収された有機層に、イオン交換水４０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０．５５部を加えて攪拌し、ろ過した。得られたろ液を濃縮し、酢酸エチル１００部を加えて攪拌し、ろ過することにより、式（Ｉ−２９）で表される塩１１．９８部を得た。これを「Ｉ−２９」という。
ＭＡＳＳ（ＥＳＩ（＋）Ｓｐｅｃｔｒｕｍ）：Ｍ^＋ ３０５．１
ＭＡＳＳ（ＥＳＩ（−）Ｓｐｅｃｔｒｕｍ）：Ｍ⁻ ５６９．２ Example 2 [Synthesis of salt represented by formula (I-29)]

12.82 parts of a compound represented by the formula (I-29-a) and 102.56 parts of chloroform were charged into a reactor and stirred at 23 ° C. for 30 minutes. Thereafter, 2.94 parts of triethylamine was added, and then 5.84 parts of a compound represented by the formula (I-29-b) were charged and stirred at about 23 ° C. for 3 hours. To the obtained reaction solution, 40 parts of ion-exchanged water and 30 parts of chloroform were added and stirred at 23 ° C. for 30 minutes. Then, it left still and liquid-separated and obtained the organic layer. To the recovered organic layer, 40 parts of ion-exchanged water was 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. 0.55 parts of activated carbon was added to the collected organic layer, stirred and filtered. The obtained filtrate was concentrated, 100 parts of ethyl acetate was added, stirred, and filtered to obtain 11.98 parts of the salt represented by the formula (I-29). This is referred to as “I-29”.
MASS (ESI (+) Spectrum): M ⁺ 305.1
MASS (ESI (−) Spectrum): M ^- 569.2

以下、これらの化合物をその式番号に応じて、「モノマー（ａ１−１−２）」などという。 Synthesis of Resin (A) The compounds used for the synthesis of resin (A) are shown below.

Hereinafter, these compounds are referred to as “monomer (a1-1-2)” or the like according to the formula number.

Synthesis Example 1 [Synthesis of Resin A1]
As the monomer, using monomer (a1-1-2), monomer (a1-2-3), monomer (a2-1-1), monomer (a3-2-3) and monomer (a3-1-1), The molar ratio (monomer (a1-1-2): monomer (a1-2-3): monomer (a2-1-1): monomer (a3-2-3): monomer (a3-1-1)) It mixed so that it might become 30: 14: 6: 20: 30, and 1.5 mass times dioxane of the total monomer amount was added, and it was set as the solution. 1 mol% and 3 mol% of azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators are added to the solution, respectively, with respect to the total monomer amount, and these are 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 resin thus obtained is again dissolved in dioxane, and a solution obtained by pouring the solution into a methanol / water mixed solvent is precipitated twice, and the resin is filtered twice to perform a reprecipitation operation twice. 8 × 10 ³ resin A1 (copolymer) was obtained with a yield of 77%. This resin A1 has the following structural units.

Synthesis Example 2 [Synthesis of Resin A2]
As the monomer, monomer (a1-1-2), monomer (a2-1-1) and monomer (a3-1-1) were used, and the molar ratio (monomer (a1-1-2): monomer (a2-1) -1): The monomer (a3-1-1)) was mixed so as to be 50:25:25, and 1.5 mass times dioxane of the total monomer amount was added to prepare a solution. 1 mol% and 3 mol% of azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators are added to the solution, respectively, based on the total monomer amount, and these are heated at 80 ° C. for about 8 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 resin thus obtained 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 9. 2 × 10 ³ resin A2 (copolymer) was obtained with a yield of 60%. This resin A2 has the following structural units.

Synthesis Example 3 [Synthesis of Resin A3]
Monomer (a1-1-2), monomer (a1-5-1), monomer (a2-1-1), monomer (a3-2-3) and monomer (a3-1-1) are mixed in a molar ratio ( Monomer (a1-1-2): Monomer (a1-5-1): Monomer (a2-1-1): Monomer (a3-2-3): Monomer (a3-1-1)) is 30:14 : 6: 20: 30 The mixture was mixed and 1.5 mass times dioxane of the total monomer amount was added to make 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 7.2. A × 10 ³ copolymer A3 was obtained with a yield of 78%. This resin A3 has the following structural units.

Synthesis Example 4 [Synthesis of Resin A4]
As the monomer, using monomer (a1-1-3), monomer (a1-5-1), monomer (a2-1-1), monomer (a3-2-3) and monomer (a3-1-1), The molar ratio (monomer (a1-1-3): monomer (a1-5-1): monomer (a2-1-1): monomer (a3-2-3): monomer (a3-1-1)) , 30: 14: 6: 20: 30, and 1.5 mass times dioxane of the total monomer amount was added to make 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. × 10 ³ of the resin A4 (copolymer) was obtained in 62% yield. This resin A4 has the following structural units.

Synthesis Example 5 [Synthesis of Resin X1]
Monomer (a4-1-7) was used as a monomer, and 1.5 mass times dioxane of the total monomer amount was added to prepare a solution. Azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were added to the solution in an amount of 0.7 mol% and 2.1 mol%, respectively, with respect to the total monomer amount, and these were added at 75 ° C. Heated for about 5 hours. 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 resin thus obtained was dissolved again in dioxane, and the solution obtained by pouring the solution into a methanol / water mixed solvent was precipitated twice, and the resin was filtered twice to perform the reprecipitation operation twice. 8 × 10 ⁴ resin X1 was obtained with a yield of 77%. This resin X1 has the following structural units.

Examples 3-11, Comparative Example 1
<Preparation of resist composition>
As shown in Table 9, each component was mixed and dissolved, and further filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist composition.

<Acid generator>
I-1: Salt represented by formula (I-1) I-29: Salt represented by formula (I-29) Z1:

<Resin>
A1: Resin A1
A2: Resin A2
A3: Resin A3
A4: Resin A4
X1: Resin X1
<Basic compound: Quencher>
C1: 2,6-Diisopropylaniline

＜溶剤＞
プロピレングリコールモノメチルエーテルアセテート ２６５．０部
プロピレングリコールモノメチルエーテル ２０．０部
２−ヘプタノン ２０．０部
γ−ブチロラクトン ３．５部

<Solvent>
Propylene glycol monomethyl ether acetate 265.0 parts Propylene glycol monomethyl ether 20.0 parts 2-heptanone 20.0 parts γ-butyrolactone 3.5 parts

(Evaluation as a resist composition for ArF)
An organic antireflective coating composition [ARC-29; manufactured by Nissan Chemical Co., Ltd.] was applied onto a 12-inch silicon wafer and baked at 205 ° C. for 60 seconds to obtain a thickness of 780 mm. An organic antireflection film was formed. Next, the above resist composition was spin-coated on the organic antireflection film so that the film thickness after drying was 85 nm.
After applying the resist composition, the obtained silicon wafer was pre-baked (PB) for 60 seconds on the direct hot plate at the temperature described in the “PB” column of Table 9. Using the ArF excimer stepper for immersion exposure [XT: 1900 Gi; manufactured by ASML, NA = 1.35, 3/4 Annular XY polarized light] on the wafer on which the resist composition film is thus formed, the exposure amount is stepwise. The line and space pattern was subjected to immersion exposure. Note that ultrapure water was used as the immersion medium.
After the exposure, post exposure bake (PEB) was performed on the hot plate at a temperature described in the “PEB” column of Table 9 for 60 seconds, and further with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 60 seconds. Paddle development was performed to obtain a resist pattern.

  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 wall surface of the resist pattern after the lithography process is observed with a scanning electron microscope.
What is 4.0 nm or less
What exceeds 4.0 nm and is 4.5 nm or less.
What exceeded 4.5 nm was set as x.
The results are shown in Table 10.

  If the resist composition of this invention is used, the resist pattern which has the outstanding line edge roughness (LER) can be obtained. Therefore, the resist composition of the present invention is useful for fine processing of semiconductors, and the salt (I) capable of realizing such a resist composition is industrially applicable.

Claims (10)

A resist composition comprising a salt represented by formula (I) and a resin that is insoluble or hardly soluble in an aqueous alkali solution and can be dissolved in an aqueous alkali solution by the action of an acid.

[In the formula (I),
Q ¹ and Q ² are the same or different and each represents a fluorine atom or a C 1-6 perfluoroalkyl group.
X ¹ represents a single bond or —NR ¹ —.
X ² represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.
W represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, and the methylene group constituting the alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group, The hydrogen atom contained in the alicyclic hydrocarbon group is a hydroxy group, 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 12 carbon atoms, or a carbon number. It may be replaced by 6-10 aromatic hydrocarbon groups.
R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Z ⁺ represents an organic cation.
L ¹ represents a group represented by any one of formulas (b1-1) to (b1-8). Incidentally, * in Formula (b1-1) ~ formula (b1-8) represents a bond, right * binds to ^{X 1.}

In formula (b1-1) to formula (b1-8),
L ^b2 represents a divalent aliphatic saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^b3 and L ^b4 each independently represent a C 1-12 divalent aliphatic saturated hydrocarbon group. However, the upper limit of the total carbon number of L ^b3 and L ^b4 is 13.
L ^b5 and L ^b6 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 14 carbon atoms. However, the upper limit of the total carbon number of L ^b5 and L ^b6 is 15.
L ^b7 and L ^b8 each independently represent a C1-C15 divalent aliphatic saturated hydrocarbon group. However, the upper limit of the total carbon number of L ^b7 and L ^b8 is 16.
L ^b9 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 13 carbon atoms.
L ^b10 represents a divalent alicyclic hydrocarbon group having 3 to 14 carbon atoms or a divalent aliphatic saturated hydrocarbon group having 4 to 14 carbon atoms, and the divalent aliphatic saturated hydrocarbon group is an alkane. The group which combined the diyl group and the bivalent alicyclic hydrocarbon group is represented. However, the upper limit of the total carbon number of L ^b9 and L ^b10 is 14.
L ^b11 and L ^b13 each independently represent a ^C 1-11 divalent aliphatic saturated hydrocarbon group.
L ^b12 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 10 carbon atoms. However, the upper limit of the total carbon number of L ^b11 , L ^b12 and L ^b13 is 12.
L ^b14 and L ^b16 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 13 carbon atoms.
L ^b15 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms. However, the upper limit of the total carbon number of L ^b14 , L ^b15 and L ^b16 is 14.
L ^b17 and L ^b18 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms. However, the upper limit of the total carbon number of L ^b17 and L ^b18 is 13. ]   W in formula (I) is an adamantyl group, cyclohexyl group or norbornyl group, and the methylene group constituting the adamantyl group, cyclohexyl group or norbornyl group is replaced with an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group. The hydrogen atom contained in the adamantyl group, cyclohexyl group or norbornyl group may be a hydroxy group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an alicyclic carbonization having 3 to 12 carbon atoms. The resist composition according to claim 1, which may be replaced with a hydrogen group or an aromatic hydrocarbon group having 6 to 10 carbon atoms. L ^{1 in the} formula (I) is a group represented by * —CO—O— (CH ₂ ) _u1 —O—CO— (CH ₂ ) _u2 — or the formula (L ¹ —A). 2. The resist composition according to 2.

(U1 and u2 are the same or different and represent an integer of 1 to 6. u3 represents 0 or 1.
* Represents a bond with a carbon atom bonded to Q ¹ and Q ² . ) The resist composition according to claim ¹ , wherein L ^{1 in the} formula (I) is a group represented by the formula (L ¹ -A).

(U3 represents 0 or 1. * represents a bond with a carbon atom bonded to Q ¹ and Q ² .
) The resist composition according to claim 1, wherein L ^{1 in the} formula (I) is a group represented by the formula (L ¹ -A), and X ¹ is a single bond.

(U3 represents. * Is 0 or 1, represents a bond to the carbon atom bonded with ^{Q 1} and ^{Q 2.)} The resist composition according to claim 1, wherein Z ^{+ in} formula (I) is a triarylsulfonium cation. The resist composition according to any one of claims 1 to 6, wherein the resin is a resin having a structural unit represented by the following formula (a1-2).

[In the formula (a1-2),
L ^a2 represents an oxygen atom or a group represented by ^* —O— (CH ₂ ) _k1 —CO—O— (k1 represents an integer of 1 to 7, and * represents a bond to a carbonyl group). Represent.
R ^a5 represents a hydrogen atom or a methyl group.
R ^a7 represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms.
n1 represents an integer of 0 to 10.
n1 ′ represents an integer of 0 to 3. ]   Furthermore, the resist composition in any one of Claims 1-7 containing a basic compound. (1) The process of apply | coating the resist composition in any one of Claims 1-8 on a board | substrate,
(2) A step of drying the composition after application to form a composition layer,
(3) a step of exposing the composition layer;
(4) a step of heating the composition layer after exposure, and (5) a step of developing the composition layer after heating,
A method for producing a resist pattern including: A salt represented by the following formula (I):

[In the formula (I),
Q ¹ and Q ² are the same or different and each represents a fluorine atom or a C 1-6 perfluoroalkyl group.
X ¹ represents a single bond or —NR ¹ —.
X ² represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.
W represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, and the methylene group constituting the alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom, a carbonyl group or a sulfonyl group, The hydrogen atom contained in the alicyclic hydrocarbon group is a hydroxy group, 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 12 carbon atoms, or a carbon number. It may be replaced by 6-10 aromatic hydrocarbon groups.
R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Z ⁺ represents an organic cation.
L ¹ represents a group represented by any one of formulas (b1-1) to (b1-8). Incidentally, * in Formula (b1-1) ~ formula (b1-8) represents a bond, right * binds to ^{X 1.}

In formula (b1-1) to formula (b1-8),
L ^b2 represents a divalent aliphatic saturated hydrocarbon group having 1 to 15 carbon atoms.
L ^b3 and L ^b4 each independently represent a C 1-12 divalent aliphatic saturated hydrocarbon group. However, the upper limit of the total carbon number of L ^b3 and L ^b4 is 13.
L ^b5 and L ^b6 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 14 carbon atoms. However, the upper limit of the total carbon number of L ^b5 and L ^b6 is 15.
L ^b7 and L ^b8 each independently represent a C1-C15 divalent aliphatic saturated hydrocarbon group. However, the upper limit of the total carbon number of L ^b7 and L ^b8 is 16.
L ^b9 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 13 carbon atoms.
L ^b10 represents a divalent alicyclic hydrocarbon group having 3 to 14 carbon atoms or a divalent aliphatic saturated hydrocarbon group having 4 to 14 carbon atoms, and the divalent aliphatic saturated hydrocarbon group is an alkane. The group which combined the diyl group and the bivalent alicyclic hydrocarbon group is represented. However, the upper limit of the total carbon number of L ^b9 and L ^b10 is 14.
L ^b11 and L ^b13 each independently represent a ^C 1-11 divalent aliphatic saturated hydrocarbon group.
L ^b12 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 10 carbon atoms. However, the upper limit of the total carbon number of L ^b11 , L ^b12 and L ^b13 is 12.
L ^b14 and L ^b16 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 13 carbon atoms.
L ^b15 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms. However, the upper limit of the total carbon number of L ^b14 , L ^b15 and L ^b16 is 14.
L ^b17 and L ^b18 each independently represent a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms. However, the upper limit of the total carbon number of L ^b17 and L ^b18 is 13. ]]