JP5708170B2 - Salt and resist composition - Google Patents

Description

  The present invention relates to a salt and a resist composition.

A resist composition used for fine processing of a semiconductor using a lithography technique contains an acid generator.
Patent Document 1 describes a resist composition containing a salt represented by the formula (X1) as a salt for an acid generator.

JP 2007-224008 A

  In the case of a conventional salt, there are cases where the resolution and line edge roughness of an obtained pattern cannot always be satisfied by using a resist composition containing the salt.

［式（Ｉ）中、Ｗ^１は、炭素数３〜３６の飽和炭化水素環を表し、該飽和炭化水素環に含まれる水素原子は炭素数１〜６のアルキル基で置換されていてもよく、該飽和炭化水素環に含まれる−ＣＨ_２−は、−Ｏ−、−ＳＯ_２−又は−ＣＯ−で置き換わっていてもよい。
Ｌ^１は、単結合又は２価の炭素数１〜１７の飽和炭化水素基を表し、該２価の飽和炭化水素基に含まれる水素原子はフッ素原子で置換されていてもよく、該２価の飽和炭化水素基に含まれる−ＣＨ_２−は、−Ｏ−又は−ＣＯ−で置き換わっていてもよい。
Ｒ¹及びＲ²は、それぞれ独立に、フッ素原子を有してもよい炭素数１〜６のアルキル基を表す。
Ｒ^３及びＲ^４は、それぞれ独立に、フッ素原子又は炭素数１〜６のペルフルオロアルキル基を表す。
Ｚ^＋は、有機カチオンを表す。］ The present invention includes the following inventions.
[1] A salt represented by the formula (I).

[In Formula (I), W ¹ represents a saturated hydrocarbon ring having 3 to 36 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon ring may be substituted with an alkyl group having 1 to 6 carbon atoms. And —CH ₂ — contained in the saturated hydrocarbon ring may be replaced by —O—, —SO ₂ — or —CO—.
L ¹ represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, a hydrogen atom contained in the divalent saturated hydrocarbon group may be substituted with a fluorine atom, and the divalent —CH ₂ — contained in the saturated hydrocarbon group may be replaced by —O— or —CO—.
R ¹ and R ² each independently represents a C 1-6 alkyl group which may have a fluorine atom.
R ³ and R ⁴ each independently represents a fluorine atom or a C 1-6 perfluoroalkyl group.
Z ⁺ represents an organic cation. ]

［式（ＩＩ）中、Ｌ^１、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４及びＺ^＋は、上記と同じ意味を表す。］ [2] The salt according to [1] represented by the formula (II).

[In Formula (II), L ¹ , R ¹ , R ² , R ³ , R ⁴ and Z ⁺ represent the same meaning as described above. ]

[3] An acid generator containing the salt according to [1] or [2].

[4] An acid generator and a resin according to [3], wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution. A resist composition, which is a resin that can be dissolved in

[5] The resist composition according to [4], further comprising a basic compound.

[6] (1) A step of applying the resist composition according to [4] or [5] on a substrate,
(2) a step of removing the solvent from the composition after coating to form a composition layer;
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) A pattern forming method including a step of developing the heated composition layer using a developing device.

  According to the salt of the present invention, a pattern having excellent resolution and line edge roughness can be formed using a resist composition containing the salt.

［式（Ｉ）中、Ｗ^１は、炭素数３〜３６の飽和炭化水素環を表し、該飽和炭化水素環に含まれる水素原子は、炭素数１〜６のアルキル基で置換されていてもよく、該飽和炭化水素環に含まれる−ＣＨ_２−は、−Ｏ−、−ＳＯ_２−又は−ＣＯ−で置き換わっていてもよい。
Ｌ^１は、単結合又は２価の炭素数１〜１７の飽和炭化水素基を表し、該２価の飽和炭化水素基に含まれる水素原子はフッ素原子で置換されていてもよく、該２価の飽和炭化水素基に含まれる−ＣＨ_２−は、−Ｏ−又は−ＣＯ−で置き換わっていてもよい。
Ｒ¹及びＲ²は、それぞれ独立に、フッ素原子を有してもよい炭素数１〜６のアルキル基を表す。
Ｒ^３及びＲ^４は、それぞれ独立に、フッ素原子又は炭素数１〜６のペルフルオロアルキル基を表す。
Ｚ^＋は、有機カチオンを表す。］ <salt>
The salt of the present invention is a salt represented by the formula (I) (hereinafter sometimes referred to as “salt (I)”).

[In Formula (I), W ¹ represents a saturated hydrocarbon ring having 3 to 36 carbon atoms, and the hydrogen atom contained in the saturated hydrocarbon ring may be substituted with an alkyl group having 1 to 6 carbon atoms. Well, —CH ₂ — contained in the saturated hydrocarbon ring may be replaced by —O—, —SO ₂ — or —CO—.
L ¹ represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, a hydrogen atom contained in the divalent saturated hydrocarbon group may be substituted with a fluorine atom, and the divalent —CH ₂ — contained in the saturated hydrocarbon group may be replaced by —O— or —CO—.
R ¹ and R ² each independently represents a C 1-6 alkyl group which may have a fluorine atom.
R ³ and R ⁴ each independently represents a fluorine atom or a C 1-6 perfluoroalkyl group.
Z ⁺ represents an organic cation. ]

  Here, the saturated hydrocarbon ring may be monocyclic or polycyclic. Examples thereof include monocyclic saturated hydrocarbon rings such as cycloalkane rings (for example, cyclopentane ring, cyclohexane ring, methylcyclohexane ring, dimethylcyclohexane ring, cycloheptane ring, cyclooctane ring). Examples thereof include polycyclic saturated hydrocarbon rings such as rings obtained by hydrogenating condensed aromatic rings (for example, hydronaphthalene ring) and bridged rings (for example, adamantane ring, norbornane ring, methylnorbornane ring). Further, a group in which a bridged ring (for example, norbornane ring) and a single ring (for example, cycloheptane ring, cyclohexane ring) or a polycyclic (for example, decahydronaphthalene ring) or bridged rings are condensed as shown below. Group; a ring in which these are combined (methylcyclohexane ring, dimethylcyclohexane ring, methylnorbornene ring) and the like.

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

The saturated cyclic hydrocarbon ring may have a substituent. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms.
Examples of the alkyl group 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, an n-pentyl group, an n-hexyl group, and a cyclohexyl group. Can be mentioned.

W ¹ is preferably a ring represented by the formula (w1-1), a ring represented by the formula (w1-2) or a ring represented by the formula (w1-3), and the formula (w1-1) The ring represented is more preferred.

Examples of the divalent saturated hydrocarbon group include a linear alkanediyl group, a branched alkanediyl group, a monocyclic or polycyclic divalent saturated cyclic hydrocarbon group, and two of these groups. A combination of the above may also be used.
Specifically, methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1 , 6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group , Dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1, Linear alkylene groups such as 17-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-2,2-diyl group;
On the side of an alkyl group (particularly an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group) Having a chain, for example, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, Branched alkylene such as 2-methylbutane-1,4-diyl group;
Cycloalkanediyl groups such as cyclobutane-1,3-diyl group, 1,3-cyclopentane-1,3-diyl group, cyclohexane-1,4-diyl group silene group, cyclooctane-1,5-diyl group, etc. A monocyclic divalent saturated cyclic hydrocarbon group which is
Polycyclic divalent saturated ring such as norbornane-1,4-diyl group, norbornane-2,5-diyl group, 1,5-adamantane-1,5-diyl group, adamantane-2,6-diyl group, etc. A hydrocarbon group etc. are mentioned.

Examples of the group in which —CH ₂ — contained in the divalent saturated hydrocarbon group is replaced by —O— or —CO— include formula (b1-1) to formula (b1-6).
Incidentally, the formula (b1-1) ~ formula (b1-6) are described together the left and right in formula (I), and the left ^{C (R 3) (R 4} ) - bound to, the right side Bonded with ring W. The same applies to specific examples of the following formulas (b1-1) to (b1-6).

In formula (b1-1) to formula (b1-6),
L ^b2 represents a single bond or an alkanediyl group having 1 to 15 carbon atoms.
L ^b3 represents a single bond or an alkanediyl group having 1 to 12 carbon atoms.
L ^b4 represents an alkanediyl group having 1 to 13 carbon atoms.
L ^b5 represents an alkanediyl group having 1 to 15 carbon atoms.
L ^b6 and L ^b7 each independently represent an alkylene group having 1 to 15 carbon atoms.
L ^b8 represents an alkanediyl group having 1 to 14 carbon atoms.
L ^b9 represents an alkanediyl group having 1 to 11 carbon atoms.
L ^b10 represents a saturated hydrocarbon group having 1 to 11 carbon atoms.

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.

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

  Examples of the perfluoroalkyl group 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. Can be mentioned.

R ³ and R ⁴ are preferably a trifluoromethyl group or a fluorine atom, and more preferably a fluorine atom.

［式（ＩＩ）〜式（ＩＶ）中、Ｒ^１〜Ｒ^４及びＬ^１は、上記と同じ意味を表す。］ Examples of the salt represented by the formula (I) include salts represented by the following formulas (II) to (IV). Among these, a salt represented by the formula (II) is preferable.

[In formula (II) to formula (IV), R ^{1 to} R ⁴ and L ¹ represent the same meaning as described above. ]

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

Among the above, salts represented by the following are preferable.

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

Z ⁺ is preferably represented by any one of formulas (b2-1) to (b2-4).

In formulas (b2-1) to (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 Represents 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, and 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 ^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 are the same or different from each other, and when n2 is an integer of 2 or more, the plurality of R ^b8 are the same or different from each other.

R ^b9 and R ^b10 each independently represent an aliphatic hydrocarbon group having 1 to 18 carbon atoms or a saturated cyclic hydrocarbon group having 3 to 18 carbon atoms.
R ^b11 represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 18 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 aliphatic hydrocarbon group of R ^{b9 to} R ^b11 preferably has 1 to 12 carbon atoms, and the saturated cyclic hydrocarbon group preferably has 3 to 18 carbon atoms, more preferably 4 to 12 carbon atoms.
R ^b12 represents an aliphatic hydrocarbon group having 1 to 12 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 aromatic hydrocarbon group is an aliphatic hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a saturated cyclic hydrocarbon group having 3 to 18 carbon atoms, or an alkylcarbonyloxy having 1 to 12 carbon atoms. It may be substituted with a group.
R ^b9 and R ^b10 , and R ^b11 and R ^b12 may be independently bonded to each other to form a 3- to 12-membered ring (preferably a 3- to 7-membered ring), These rings —CH ₂ — may be replaced by —O—, —S— or —CO—.

R ^{b13 to} R ^b18 each independently represent a hydroxy group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
L ^b11 represents -S- or -O-.
o2, p2, s2, and t2 each independently represents an integer of 0 to 5.
q2 and r2 each independently represents an integer of 0 to 4.
u2 represents 0 or 1.
When o2 is an integer of 2 or more, the plurality of R ^b13 are the same or different from each other, and when p2 is an integer of 2 or more, the plurality of R ^b14 are the same or different from each other, and s2 is an integer of 2 or more In this case, the plurality of R ^b17 are the same or different from each other. When u2 is an integer of 2 or more, the plurality of R ^b18 are the same or different from each other. When q2 is an integer of 2 or more, the plurality of R ^b15 are the same or different from each other. When r2 is an integer of 2 or more, the plurality of R ^b16 are the same or different from each other.

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

Examples of the aliphatic hydrocarbon group include methyl group, ethyl group, n-propyl group, 1-methylethyl group (isopropyl group), n-butyl group, 1,1-dimethylethyl group (tert-butyl group), 2, 2-dimethylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, 1-ethylpropyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, n-hexyl group, 1-propylbutyl group, pentyl group, 1-methylpentyl group, 1,4-dimethylhexyl group, heptyl group, 1-methylheptyl group, octyl group, Examples thereof include alkyl groups such as nonyl group, decyl group, undecyl group, and dodecyl group. Among them, preferred aliphatic hydrocarbon groups are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group and 2- An ethylhexyl group.
Preferred saturated cyclic hydrocarbon groups are cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclodecyl group, 2-alkyl-2-adamantyl group, 1- (1-adamantyl) -1-alkyl group, And an isobornyl group.
Preferred aromatic hydrocarbon groups are phenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-cyclohexylphenyl group, 4-methoxyphenyl group, biphenylyl group, naphthyl group. It is.
Examples of the aliphatic hydrocarbon group (aralkyl group) whose substituent is an aromatic hydrocarbon group include a benzyl group.
Examples of the ring formed by R ^b9 and R ^b10 include a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathian-4-ium ring.
^Examples of the ring formed by R ^b11 and R ^b12 include an oxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, and an oxoadamantane ring.

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

In formula (b2-1-1), R ^{b19 to} R ^b21 each independently represent a halogen atom (more preferably a fluorine atom), a hydroxy group, an aliphatic hydrocarbon group having 1 to 18 carbon atoms, or 3 to 3 carbon atoms. 18 represents a saturated cyclic hydrocarbon group or an alkoxy group having 1 to 12 carbon atoms.
The aliphatic hydrocarbon group preferably has 1 to 12 carbon atoms, and the saturated cyclic hydrocarbon group preferably has 4 to 18 carbon atoms.
The aliphatic hydrocarbon group may be substituted with a hydroxy group, an alkoxy group having 1 to 12 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms.
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.
v2, w2 and x2 each independently represent an integer of 0 to 5 (preferably 0 or 1). When v2 is an integer of 2 or more, the plurality of R ^b19 are the same or different from each other, and when w2 is an integer of 2 or more, the plurality of R ^b20 are the same or different from each other, and x2 is an integer of 2 or more In this case, the plurality of R ^b21 are the same or different from each other.
Among them, 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. More preferably, it is a hydroxy group or an alkyl group having 1 to 4 carbon atoms.

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

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

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

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

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

［式中、Ｒ^b19〜Ｒ^b21、ｖ２〜ｘ２は前記と同じ意味を表す。］ Examples of the salt (I) include the following.

[ ^Wherein , R ^{b19 to} R ^b21 and v2 to x2 represent the same meaning as described above. ]

Furthermore, the following salts are more preferable.

式（ｂ２−ａ）で表される化合物としては、ヘプタフルオロ酪酸無水物、ペンタフルオロプロピオン酸無水物が好ましい。
式（ｂ２−ｂ）で表される塩としては、トリフェニルスルホニウム ４−オキソ−１−アダマンチルオキシカルボニルジフルオロメタンスルホナートが好ましい。 The salt (I) can be produced by a method known in the art.
For example, the salt represented by the formula (I) can be obtained by reacting the compound represented by the formula (b2-a) with the salt represented by the formula (b2-b).

As the compound represented by the formula (b2-a), heptafluorobutyric anhydride and pentafluoropropionic anhydride are preferable.
As the salt represented by the formula (b2-b), triphenylsulfonium 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate is preferable.

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

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

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

<Monomer (a1) having an acid labile group>
The term “acid-labile group” means a group that cleaves a leaving group upon contact with an acid to form a hydrophilic group (for example, a hydroxy group or a carboxy group). Examples of the acid labile group include an alkoxycarbonyl group represented by the formula (1) in which —O— is bonded to a tertiary carbon atom. Hereinafter, the group represented by the formula (1) may be referred to as “acid-labile group (1)”.

式（１）中、Ｒ^a1〜Ｒ^a3は、それぞれ独立に、炭素数１〜８の脂肪族炭化水素基又は炭素数３〜２０の飽和環状炭化水素基を表すか或いはＲ^a1及びＲ^a2は互いに結合して炭素数３〜２０の環を形成する。＊は結合手を表す（以下同じ）。

In the formula (1), R ^{a1 to} R ^a3 each independently represent an aliphatic hydrocarbon group having 1 to 8 carbon atoms or a saturated cyclic hydrocarbon group having 3 to 20 carbon atoms, or R ^a1 and R ^a2 are Bond to each other to form a ring having 3 to 20 carbon atoms. * Represents a bond (same below).

式（１）における飽和環状炭化水素基の炭素数は、好ましくは炭素数３〜１６である。 Examples of the aliphatic hydrocarbon group include an alkyl group, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group.
The saturated cyclic hydrocarbon group may be monocyclic or polycyclic, and examples of the monocyclic saturated cyclic hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, and dimethylcyclohexyl. Cycloalkyl groups such as a group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic saturated hydrocarbon group include a decahydronaphthyl group, an adamantyl group, a norbornyl group, a methylnorbornyl group, and the following groups.

Carbon number of the saturated cyclic hydrocarbon group in Formula (1) becomes like this. Preferably it is C3-C16.

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

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 a tert-butoxycarbonyl group), 2-alkyl-2-adamantyloxycarbonyl group (in the formula (1), R ^a1 , R ^a2 and a carbon atom form an adamantyl group and R ^a3 is an alkyl group) and 1- (1-adamantyl)- 1-alkylalkoxycarbonyl group (in the formula (1), R ^a1 and R ^a2 are alkyl groups, and R ^a3 is an adamantyl group).

  The monomer (a1) having an acid labile group is preferably a monomer having an acid labile group (1) and a carbon-carbon double bond, more preferably an acid labile group (1). (Meth) acrylic monomer having Here, (meth) acryl represents acryl and / or methacryl.

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

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

[In Formula (a1-1) and Formula (a1-2), L ^a1 and L ^a2 each independently represent —O— or ^* —O— (CH ₂ ) _k1 —CO—O—.
k1 represents an integer of 1 to 7. * Represents a bond with -CO-.
R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group.
R ^a6 and R ^a7 each independently represent an aliphatic hydrocarbon group having 1 to 8 carbon atoms or a saturated cyclic hydrocarbon group having 3 to 10 carbon atoms.
m1 represents the integer of 0-14.
n1 represents an integer of 0 to 10. ]

L ^a1 and L ^a2 are preferably —O— or ^* —O— (CH ₂ ) _f1 —CO—O— (wherein f1 represents an integer of 1 to 4), more preferably —O—. It is. k1 is preferably an integer of 1 to 4, more preferably 1.
R ^a4 and R ^a5 are preferably methyl groups.
Examples of the aliphatic hydrocarbon group for R ^a6 and R ^a7 include an alkyl group, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. The aliphatic hydrocarbon group represented by R ^a6 and R ^a7 preferably has 6 or less carbon atoms. The saturated cyclic hydrocarbon group preferably has 8 or less carbon atoms, more preferably 6 or less.
The saturated cyclic hydrocarbon group for R ^a6 and R ^a7 may be either monocyclic or polycyclic. Examples of the monocyclic saturated cyclic hydrocarbon group include a cyclopentyl group, a cyclohexyl group, and a methylcyclohexyl group. Cycloalkyl groups such as a group, dimethylcyclohexyl group, cycloheptyl group, and cyclooctyl group. Examples of the polycyclic saturated hydrocarbon group include decahydronaphthyl group, adamantyl group, norbornyl group, methylnorbornyl group, and the following groups.

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.

  Examples of the monomer represented by the formula (a1-1) include the following. Among them, 2-methyladamantan-2-yl (meth) acrylate, 2-ethyladamantan-2-yl (meth) acrylate and 2-isopropyladamantan-2-yl (meth) acrylate are preferable, and 2-methyladamantan-2-yl Il methacrylate, 2-ethyladamantan-2-yl methacrylate and 2-isopropyladamantan-2-yl methacrylate are more preferred.

  Examples of the monomer represented by the formula (a1-2) include the following. Among these, 1-ethylcyclohexane-1-yl (meth) acrylate is preferable, and 1-ethylcyclohexane-1-yl methacrylate is more preferable.

  The content of the structural unit derived from the monomer represented by the formula (a1-1) or the monomer represented by the formula (a1-2) in the resin is usually 10 to 95 mol% in all units of the resin, Preferably it is 15-90 mol%, More preferably, it is 20-85 mol%, More preferably, it is 30-60 mol%.

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

[In formula (a1-3), R ^a9 represents a hydrogen atom, a C 1-3 aliphatic hydrocarbon group optionally having a hydroxy group, a carboxy group, a cyano group, or a C 1-8 alkoxy. ^{Represents a} carbonyl group (—COOR ^a13 ), and R ^a13 represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms or a saturated cyclic hydrocarbon group having 3 to 20 carbon atoms, and the aliphatic hydrocarbon group and the saturated cyclic group The hydrogen atom contained in the hydrocarbon group may be substituted with a hydroxy group, and —CH ₂ — contained in the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group is replaced with —O— or —CO—. May be.
R ^{a10 to} R ^a12 each independently represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated cyclic hydrocarbon group having 3 to 20 carbon atoms, or R ^a10 and R ^a11 are bonded to each other to form carbon. A ring of several 3 to 20 is formed, and a hydrogen atom of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group may be substituted with a hydroxy group or the like, and the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon The group —CH ₂ — may be replaced by —O— or —CO—. ]

  Here, examples of the alkoxycarbonyl group include groups in which a carbonyl group is bonded to an alkoxy group such as a methoxycarbonyl group or an ethoxycarbonyl group.

Examples of the aliphatic hydrocarbon group which may have a hydroxy group of R ^a9 include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group.
^Examples of R ^a13 include a methyl group, an ethyl group, a propyl group, a 2-oxo-oxolan-3-yl group, and a 2-oxo-oxolan-4-yl group.
Examples of R ^{a10 to} R ^a12 include a methyl group, an ethyl group, a cyclohexyl group, a methylcyclohexyl group, a hydroxycyclohexyl group, an oxocyclohexyl group, and an adamantyl group.
Examples of the ring formed by R ^a10 , R ^a11 and the carbon to which they are bonded include saturated cyclic hydrocarbon groups, and specific examples include a cyclohexyl group and an adamantyl group.

  Examples of the monomer represented by the formula (a1-3) include, for example, 5-norbornene-2-carboxylic acid-tert-butyl, 5-norbornene-2-carboxylic acid 1-cyclohexyl-1-methylethyl, 5-norbornene- 1-methylcyclohexyl 2-carboxylate, 2-methyl-2-adamantyl 5-norbornene-2-carboxylate, 2-ethyl-2-adamantyl 5-norbornene-2-carboxylate, 5-norbornene-2-carboxylic acid 1 -(4-Methylcyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1- (4-hydroxycyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1-methyl-1- ( 4-oxocyclohexyl) ethyl, 1- (1-adamantyl) 5-norbornene-2-carboxylate And 1-methyl-ethyl.

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

Examples of the monomer having an acid labile group (1) and a carbon-carbon double bond include monomers represented by the formula (a1-4).

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

Examples of the alkyl group that may have a halogen atom include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, and a perfluoropentyl group. Perfluorohexyl group, perchloromethyl group, perbromomethyl group, periodomethyl group and the like.
Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, and an n-hexoxy group. .
Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group.
Examples of the acyloxy group include an acetyloxy group, a propionyloxy group, and a butyryloxy group.
Examples of the hydrocarbon group include an aliphatic hydrocarbon group, a saturated cyclic hydrocarbon group, and an aromatic hydrocarbon group.
As aromatic hydrocarbon group, phenyl group, naphthyl group, anthranyl group, p-methylphenyl group, p-tert-butylphenyl group, p-adamantylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, biphenyl Groups, anthryl groups, phenanthryl groups, 2,6-diethylphenyl groups, aryl groups such as 2-methyl-6-ethylphenyl, and the like.

The alkyl group for R ¹⁰ and R ¹¹ preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably a methyl group.
As the alkoxy group for R ¹¹ , C 1 or 2 is more preferable, and a methoxy group is particularly preferable.
Examples of the hydrocarbon group for R ¹² and R ¹³ include isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, cyclohexyl group, adamantyl group, A 2-alkyladamantan-2-yl group, a 1- (1-adamantyl) -1-alkyl group, an isobornyl group, and the like are preferable.
The substituent that X ^a2 and Y ^a3 may have is preferably a hydroxy group.

  Examples of the monomer represented by the formula (a1-4) include the following monomers.

  When the resin contains a structural unit derived from the monomer represented by the formula (a1-4), the content thereof is usually 10 to 95 mol%, preferably 15 to 90 mol%, based on the total unit of the resin. Yes, more preferably 20 to 85 mol%.

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

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

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

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

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

Examples of the alkyl group for R ⁸ 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, an n-pentyl group, and an n-hexyl group. An alkyl group having 1 to 4 carbon atoms is preferable, an alkyl group having 1 or 2 carbon atoms is more preferable, and a methyl group is particularly preferable.
Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. An alkoxy group having 1 to 4 carbon atoms is preferable, an alkoxy group having 1 or 2 carbon atoms is more preferable, and a methoxy group is particularly preferable.
ma is preferably 0 to 2, more preferably 0 or 1, and particularly preferably 0.

In order to obtain a copolymer resin having a structural unit derived from a monomer having such a phenolic hydroxy group, the corresponding (meth) acrylic acid ester monomer, acetyloxystyrene, and styrene are radically polymerized, and then removed with an acid. It can be obtained by acetylation.
Examples of the monomer having a phenolic hydroxy group include the following monomers.

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

  When the resin contains a structural unit derived from the monomer represented by the formula (a2-0), the content thereof is usually from 5 to 90 mol%, preferably from 10 to 85 mol%, in all units of the resin. Yes, more preferably 15 to 80 mol%.

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

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

In the formula (a2-1), L ^a3 is preferably, -O -, - O- (CH 2) f1 -CO-O- and is (wherein f1 is an integer from 1 to 4), more preferably Is —O—.
R ^a14 is preferably a methyl group.
R ^a15 is preferably a hydrogen atom.
R ^a16 is preferably a hydrogen atom or a hydroxy group.
o1 is preferably an integer of 0 to 3, more preferably 0 or 1.

  As an acid stable monomer (a2-1) which has a hydroxyadamantyl group, the following are mentioned, for example. Among them, 3-hydroxyadamantan-1-yl (meth) acrylate, 3,5-dihydroxyadamantan-1-yl (meth) acrylate and (meth) acrylic acid 1- (3,5-dihydroxyadamantan-1-yloxycarbonyl ) Methyl is preferred, 3-hydroxyadamantan-1-yl (meth) acrylate and 3,5-dihydroxyadamantan-1-yl (meth) acrylate are more preferred, 3-hydroxyadamantan-1-yl methacrylate and 3,5- More preferred is dihydroxyadamantan-1-yl methacrylate.

  When the resin contains a structural unit derived from the monomer represented by the formula (a2-1), the content thereof is usually 3 to 40 mol%, preferably 5 to 35 mol%, in all units of the resin. More preferably, it is 5-30 mol%, More preferably, it is 5-15 mol%.

<Acid-stable monomer having a lactone ring (a3)>
The lactone ring possessed by the acid stable monomer (a3) may be, for example, a monocycle such as a β-propiolactone ring, γ-butyrolactone ring, or δ-valerolactone ring, a monocyclic lactone ring and other rings The condensed ring may be used. Among these lactone rings, a γ-butyrolactone ring and a condensed ring of a γ-butyrolactone ring and another ring are preferable.

  The acid-stable monomer (a3) having a lactone ring is preferably represented by the formula (a3-1), the formula (a3-2) or the formula (a3-3). These 1 type may be used independently and may use 2 or more types together.

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

In the formula (a3-1) to the formula (a3-3), examples of L ^{a4 to} L ^a6 include those described for L ^a3 .
L ^{a4 to} L ^a6 are each independently preferably —O— or ^* —O— (CH ₂ ) _d1 —CO—O— (the d1 is an integer of 1 to 4), more preferably. Is —O—.
R ^{a18 to} R ^a21 are preferably methyl groups.
R ^a22 and R ^a23 are each independently preferably a carboxy group, a cyano group or a methyl group.
p1 to r1 are each independently preferably 0 to 2, more preferably 0 or 1.

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

  Examples of the acid-stable monomer (a3-1) having a γ-butyrolactone ring that serve as an acid-labile monomer include the following.

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

  Among the acid stable monomers (a3-2) having a condensed ring of γ-butyrolactone ring and norbornane ring, the following can be exemplified as those that function as acid labile monomers.

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

  Among the monomers (a3-3) having a condensed ring of a γ-butyrolactone ring and a cyclohexane ring, examples of those that function as acid labile monomers include the following.

Among acid-stable monomers (a3) having a lactone ring, (meth) acrylic acid (5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonan-2-yl, (meth) acrylic Acid tetrahydro-2-oxo-3-furyl, 2- (5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonan-2-yloxy) -2-oxoethyl (meth) acrylate Are preferred, and those in the form of methacrylate are more preferred.

  When the resin contains a structural unit derived from the monomer represented by the formula (a3-1), the formula (a3-2) or the formula (a3-3), the content thereof is usually 5 for each unit of the resin. It is -50 mol%, Preferably it is 10-45 mol%, More preferably, it is 15-40 mol%. When the resin contains a structural unit derived from the acid-stable monomer (a3) having a lactone ring, the total content is usually 5 to 60 mol%, preferably 15 to 55 mol%, in all units of the resin. is there.

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

式（ａ４−３）中、Ｒ^a25及びＲ^a26は、それぞれ独立に、水素原子、ヒドロキシ基を有していてもよい炭素数１〜３の脂肪族炭化水素基、シアノ基、カルボキシ基又はアルコキシカルボニル基（−ＣＯＯＲ^a27）を表すか、或いはＲ^a25及びＲ^a26は互いに結合して−ＣＯ−Ｏ−ＣＯ−を形成し、
Ｒ^a27は、炭素数１〜１８の脂肪族炭化水素基又は炭素数３〜１８の飽和環状炭化水素基を表し、該脂肪族炭化水素基及び該飽和環状炭化水素基の−ＣＨ_２−は、−Ｏ−又は−ＣＯ−で置き換わっていてもよい。但し−ＣＯＯＲ^a27が酸不安定基となるものは除く（即ちＲ^a27は、三級炭素原子が−Ｏ−と結合するものを含まない）。

In formula (a4-3), R ^a25 and R ^a26 each independently represent a hydrogen atom, a C 1-3 aliphatic hydrocarbon group optionally having a hydroxy group, a cyano group, a carboxy group or an alkoxy group. Represents a carbonyl group (—COOR ^a27 ) or R ^a25 and R ^a26 combine with each other to form —CO—O—CO—;
R ^a27 represents an aliphatic hydrocarbon group having 1 to 18 carbon atoms or a saturated cyclic hydrocarbon group having 3 to 18 carbon atoms, and —CH ₂ — of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group is -O- or -CO- may be substituted. However, those in which —COOR ^a27 is an acid labile group are excluded (that is, R ^a27 does not include those in which a tertiary carbon atom is bonded to —O—).

^Examples of the aliphatic hydrocarbon group which may have a hydroxyl group for R ^a25 and R ^a26 include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group.
The aliphatic hydrocarbon group for R ^a27 preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms. The saturated cyclic hydrocarbon group preferably has 4 to 18 carbon atoms, more preferably 4 to 12 carbon atoms.
^Examples of R ^a27 include a methyl group, an ethyl group, a propyl group, a 2-oxo-oxolan-3-yl group, and a 2-oxo-oxolan-4-yl group.

  Examples of the acid-stable monomer (a4-3) having a norbornene ring include 2-norbornene, 2-hydroxy-5-norbornene, 5-norbornene-2-carboxylic acid, methyl 5-norbornene-2-carboxylate, 5- Examples include norbornene-2-carboxylic acid 2-hydroxy-1-ethyl, 5-norbornene-2-methanol, and 5-norbornene-2,3-dicarboxylic acid anhydride.

  When the resin contains a structural unit derived from another acid-stable monomer (a4), the content thereof is usually 2 to 40 mol%, preferably 3 to 30 mol%, based on the total unit of the resin. Preferably it is 5-20 mol%.

  A preferred resin (A) is a copolymer obtained by polymerizing at least a monomer (a1) having an acid labile group, an acid stable monomer (a2) having a hydroxy group, and / or an acid stable monomer (a3) having a lactone ring. It is a polymer. In this preferred copolymer, the monomer (a1) having an acid labile group is more preferably at least one of a monomer (a1-1) having an adamantyl group and a monomer (a1-2) having a cyclohexyl group. A species (more preferably a monomer (a1-1) having an adamantyl group), and an acid stable monomer (a2) having a hydroxy group, preferably an acid stable monomer (a2-1) having a hydroxyadamantyl group, and a lactone The acid-stable monomer (a3) having a ring is more preferably an acid-stable monomer (a3-1) having a γ-butyrolactone ring and an acid-stable monomer (a3-2) having a condensed ring of a γ-butyrolactone ring and a norbornane ring At least one of the following. Resin (A) can be manufactured by a well-known polymerization method (for example, radical polymerization method).

The weight average molecular weight of the resin (A) is preferably 2,500 or more (more preferably 3,000 or more, more preferably 3,500 or more), 50,000 or less (more preferably 30,000 or less, and further preferably Is 10,000 or less).
It is preferable that content of resin (A) is 80 to 99 mass% in solid content of a composition.
In the present specification, the “solid content in the composition” means the total of resist composition components excluding the solvent (E) described later. The solid content in the composition and the content of the resin (A) relative thereto can be measured by a known analysis means such as liquid chromatography or gas chromatography.

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

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

式（Ｃ２）及び式（Ｃ２−１）中、Ａｒ^c1は、芳香族炭化水素基を表す。
Ｒ^c5及びＲ^c6は、それぞれ独立に、水素原子、脂肪族炭化水素基（好ましくはアルキル基又はシクロアルキル基）、飽和環状炭化水素基又は芳香族炭化水素基を表す。但し該脂肪族炭化水素基、該飽和環状炭化水素基又は該芳香族炭化水素基の水素原子は、ヒドロキシ基、アミノ基、又は炭素数１〜６のアルコキシ基で置換されていてもよく、該アミノ基は、炭素数１〜４のアルキル基で置換されていてもよい。
前記脂肪族炭化水素基は、好ましくは炭素数１〜６程度であり、前記飽和環状炭化水素基は、好ましくは炭素数５〜１０程度であり、前記芳香族炭化水素基は、好ましくは炭素数６〜１０程度である。
Ｒ^c7は、脂肪族炭化水素基（好ましくはアルキル基）、アルコキシ基、飽和環状炭化水素基（好ましくはシクロアルキル基）又は芳香族炭化水素基を表す。但し脂肪族炭化水素基、アルコキシ基、飽和環状炭化水素基及び芳香族炭化水素基の水素原子は、上記と同様の置換基を有していてもよい。
ｍ３は０〜３の整数を表す。ｍ３が２以上のとき、複数のＲ^c7は、互いに同一でも異なってもよい。
Ｒ^c7の脂肪族炭化水素基、飽和環状炭化水素基及び芳香族炭化水素基の好ましい炭素数は、上記と同じであり、Ｒ^c7のアルコキシ基は、好ましくは炭素数１〜６程度である。

In formula (C2) and formula (C2-1), Ar ^c1 represents an aromatic hydrocarbon group.
R ^c5 and R ^c6 each independently represents a hydrogen atom, an aliphatic hydrocarbon group (preferably an alkyl group or a cycloalkyl group), a saturated cyclic hydrocarbon group or an aromatic hydrocarbon group. However, the hydrogen atom of the aliphatic hydrocarbon group, the saturated cyclic hydrocarbon group or the aromatic hydrocarbon group may be substituted with a hydroxy group, an amino group, or an alkoxy group having 1 to 6 carbon atoms, The amino group may be substituted with an alkyl group having 1 to 4 carbon atoms.
The aliphatic hydrocarbon group preferably has about 1 to 6 carbon atoms, the saturated cyclic hydrocarbon group preferably has about 5 to 10 carbon atoms, and the aromatic hydrocarbon group preferably has about carbon atoms. It is about 6-10.
R ^c7 represents an aliphatic hydrocarbon group (preferably an alkyl group), an alkoxy group, a saturated cyclic hydrocarbon group (preferably a cycloalkyl group) or an aromatic hydrocarbon group. However, the hydrogen atom of an aliphatic hydrocarbon group, an alkoxy group, a saturated cyclic hydrocarbon group, and an aromatic hydrocarbon group may have a substituent similar to the above.
m3 represents an integer of 0 to 3. When m3 is 2 or more, the plurality of R ^c7 may be the same as or different from each other.
Aliphatic hydrocarbon group R ^c7, preferable number of carbon atoms of the saturated cyclic hydrocarbon group and the aromatic hydrocarbon group are the same as above, an alkoxy group of R ^c7 is independently in, preferably about 1 to 6 carbon atoms.

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

式（Ｃ３）〜式（Ｃ１１）中、Ｒ^c8は、上記Ｒ^c7で説明したいずれかの基を表す。
窒素原子と結合するＲ^c9、Ｒ^c10、Ｒ^c11〜Ｒ^c14、Ｒ^c16〜Ｒ^c19及びＲ^c22は、それぞれ独立に、Ｒ^c5及びＲ^c6で説明したいずれかの基を表す。
芳香族炭素と結合するＲ^c20、Ｒ^c21、Ｒ^c23〜Ｒ^c28は、それぞれ独立に、Ｒ^c7で説明したいずれかの基を表す。
ｏ３、ｐ３、ｑ３、ｒ３、ｓ３、ｔ３及びｕ３は、それぞれ独立に０〜３の整数を表す。ｏ３、ｐ３、ｑ３、ｒ３、ｓ３、ｔ３及びｕ３のいずれかが２以上であるとき、それぞれ、複数のＲ^c20〜Ｒ^c28のいずれかは互いに同一でも異なってもよい。
Ｒ^c15は、脂肪族炭化水素基、飽和環状炭化水素基又はアルカノイル基を表す。
ｎ３は０〜８の整数を表す。ｎ３が２以上のとき、複数のＲ^c15は、互いに同一でも異なってもよい。
Ｒ^c15の脂肪族炭化水素基は、好ましくは炭素数１〜６程度であり、飽和環状炭化水素基は、好ましくは炭素数３〜６程度であり、アルカノイル基は、好ましくは炭素数２〜６程度である。
Ｌ^c1及びＬ^c2は、それぞれ独立に、２価の脂肪族炭化水素基（好ましくはアルキレン基）、−ＣＯ−、−Ｃ（＝ＮＨ）−、−Ｃ（＝ＮＲ^c3）−、−Ｓ−、−Ｓ−Ｓ−又はこれらの組合せを表す。前記２価の脂肪族炭化水素基は、好ましくは炭素数１〜６程度である。
Ｒ^c3は、炭素数１〜４のアルキル基を表す。 Examples of the basic compound (C) include compounds represented by the formulas (C3) to (C11).

In formula (C3) to formula (C11), R ^c8 represents any of the groups described above for R ^c7 .
R ^c9 , R ^c10 , R ^{c11 to} R ^c14 , R ^{c16 to} R ^c19 and R ^c22 bonded to the nitrogen atom each independently represent any of the groups described for R ^c5 and R ^c6 .
R ^c20 , R ^c21 and R ^{c23 to} R ^c28 bonded to the aromatic carbon each independently represents any of the groups described for R ^c7 .
o3, p3, q3, r3, s3, t3 and u3 each independently represents an integer of 0 to 3. When any of o3, p3, q3, r3, s3, t3, and u3 is 2 or more, any of the plurality of R ^{c20 to} R ^c28 may be the same as or different from each other.
R ^c15 represents an aliphatic hydrocarbon group, a saturated cyclic hydrocarbon group or an alkanoyl group.
n3 represents an integer of 0 to 8. When n3 is 2 or more, the plurality of R ^c15 may be the same as or different from each other.
The aliphatic hydrocarbon group represented by R ^c15 preferably has about 1 to 6 carbon atoms, the saturated cyclic hydrocarbon group preferably has about 3 to 6 carbon atoms, and the alkanoyl group preferably has 2 to 6 carbon atoms. Degree.
L ^c1 and L ^c2 are each independently a divalent aliphatic hydrocarbon group (preferably an alkylene group), —CO—, —C (═NH) —, —C (═NR ^c3 ) —, —S—. , -SS- or a combination thereof. The divalent aliphatic hydrocarbon group preferably has about 1 to 6 carbon atoms.
R ^c3 represents an alkyl group having 1 to 4 carbon atoms.

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

Examples of the compound (C4) include piperazine.
Examples of the compound (C5) include morpholine.
Examples of the compound (C6) include piperidine and hindered amine compounds having a piperidine skeleton described in JP-A No. 11-52575.
Examples of the compound (C7) include 2,2′-methylenebisaniline.
Examples of the compound (C8) include imidazole and 4-methylimidazole.
Examples of the compound (C9) include pyridine and 4-methylpyridine.
Examples of the compound (C10) include 1,2-di (2-pyridyl) ethane, 1,2-di (4-pyridyl) ethane, 1,2-di (2-pyridyl) ethene, and 1,2-di. (4-pyridyl) ethene, 1,3-di (4-pyridyl) propane, 1,2-di (4-pyridyloxy) ethane, di (2-pyridyl) ketone, 4,4′-dipyridyl sulfide, 4, 4'-dipyridyl disulfide, 2,2'-dipyridylamine, 2,2'-dipicolylamine and the like can be mentioned.
Examples of the compound (C11) include bipyridine.

<Solvent (sometimes referred to as "solvent (E)")
The resist composition of the present invention may contain the solvent (E) in an amount of 90% by mass or more in the composition. The resist composition of the present invention containing the solvent (E) is suitable for producing a thin film resist. The content of the solvent (E) is 90% by mass or more (preferably 92% by mass or more, more preferably 94% by mass or more) and 99.9% by mass or less (preferably 99% by mass or less) in the composition.
The content of the solvent (E) can be measured by a known analysis means such as liquid chromatography or gas chromatography.

  Examples of the solvent (E) include glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate and propylene glycol monomethyl ether acetate; glycol ethers such as propylene glycol monomethyl ether; ethyl lactate, butyl acetate, amyl acetate and And esters such as ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; cyclic esters such as γ-butyrolactone; A solvent (E) may be used individually by 1 type, and may use 2 or more types together.

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

<Method for producing resist pattern>
The method for producing a resist pattern of the present invention comprises:
(1) The process of apply | coating the resist composition of this invention mentioned above on a board | substrate,
(2) a step of removing the solvent from the composition after coating to form a composition layer;
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) The process which develops the composition layer after a heating using a image development apparatus is included.

  Application of the resist composition onto the substrate can be performed by a commonly used apparatus such as a spin coater.

The removal of the solvent is performed, for example, by evaporating the solvent using a heating device such as a hot plate (so-called pre-baking) or by using a decompression device to form a composition layer from which the solvent has been removed. The As for the temperature in this case, about 50-200 degreeC is illustrated, for example. The pressure is exemplified by about 1 to 1.0 × 10 ⁵ Pa.

The obtained composition layer is exposed using an exposure machine. The exposure machine may be an immersion exposure machine. At this time, exposure is usually performed through a mask corresponding to a required pattern. Exposure light sources include those that emit laser light in the ultraviolet region such as KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F ₂ excimer laser (wavelength 157 nm), solid-state laser light source (YAG or semiconductor laser) Etc.) can be used such as those that convert the wavelength of the laser light from the above and radiate the harmonic laser light in the far ultraviolet region or the vacuum ultraviolet region. The exposure machine may irradiate an electron beam or extreme ultraviolet light (EUV) generated from plasma.

The composition layer after exposure is subjected to heat treatment (so-called post-exposure baking) for promoting the deprotection group reaction. As heating temperature, it is about 50-200 degreeC normally, Preferably it is about 70-150 degreeC.
The heated composition layer is usually developed using an alkali developer using a developing device.
The alkaline developer used here may be various alkaline aqueous solutions used in this field. Examples thereof include an aqueous solution of tetramethylammonium hydroxide and (2-hydroxyethyl) trimethylammonium hydroxide (commonly called choline).
After development, it is preferable to rinse with ultrapure water to remove water remaining on the substrate and the pattern.

<Application>
The resist composition of the present invention 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. is there.

Hereinafter, the present invention will be described in detail by way of examples. In the examples,% and parts representing the content and the amount used are based on mass unless otherwise specified.
In the following examples, the structure of the compound was confirmed by mass spectrometry (LC; Agilent 1100 type, MASS; Agilent LC / MSD type).
The weight average molecular weight is a value determined by gel permeation chromatography (HLC-8120GPC type manufactured by Tosoh Corporation, three columns are “TSKgel Multipore HXL-M”, and the solvent is tetrahydrofuran) using polystyrene as a standard product.
Column: TSKgel Multipore H _XL -M x 3 + guardcolumn (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min
Detector: RI detector Column temperature: 40 ° C
Injection volume: 100 μl
Molecular weight standard: Standard polystyrene (manufactured by Tosoh Corporation)

Example 1: Synthesis of a salt represented by the formula (B-1)

  2.00 parts of a salt represented by the formula (B-1-a) and 8.00 parts of heptafluorobutyric anhydride were charged, stirred at 120 ° C. for 15 hours, and then cooled to 23 ° C. To the obtained reaction product, 100 parts of chloroform and 66 parts of 5% aqueous sodium hydrogen carbonate solution were added and stirred at 23 ° C. for 30 minutes, followed by liquid separation. The recovered organic layer was charged with 56 parts of ion-exchanged water, stirred at 23 ° C. for 30 minutes, and then separated to recover the organic layer. This washing operation was performed 4 times. The recovered organic layer is concentrated, 50 parts of tert-butyl methyl ether is added to the resulting concentrate, and the mixture is stirred at 23 ° C. for 30 minutes, followed by filtration, which is represented by the formula (B-1). 1.88 parts of salt were obtained.

Identification of the compound represented by formula (B-1);
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (−) Spectrum): M ^- 733.0

Example 2: Synthesis of salt represented by formula (B-2)

式（Ｂ−２−ａ）で表される塩１．００部及びヘプタフルオロ酪酸無水物４．００部を仕込み、１２０℃で９時間攪拌後、２３℃まで冷却した。反応マスのＭＳを確認することにより、式（Ｂ−２−ｂ）で表される塩を確認した。

1.00 parts of a salt represented by the formula (B-2-a) and 4.00 parts of heptafluorobutyric anhydride were charged, stirred at 120 ° C. for 9 hours, and then cooled to 23 ° C. By confirming MS of the reaction mass, the salt represented by the formula (B-2-b) was confirmed.

Identification of the compound represented by the formula (B-2-b);
MS (ESI (+) Spectrum): M ⁺ 475.1
MS (ESI (−) Spectrum): M ^- 733.0

  To the obtained reaction product, 50 parts of chloroform and 41 parts of 5% aqueous sodium hydrogen carbonate solution were added and stirred at 23 ° C. for 30 minutes, followed by liquid separation. The recovered organic layer was charged with 25 parts of ion-exchanged water, stirred at 23 ° C. for 30 minutes, and then separated to recover the organic layer. This washing operation was performed 7 times. The collected organic layer was concentrated, and 10 parts of acetonitrile was added to the resulting concentrate, followed by stirring at 23 ° C. for 30 minutes and then concentration. After adding 10 parts of tert-butyl methyl ether to the obtained concentrate and stirring at 23 ° C. for 30 minutes, the supernatant was removed and then concentrated to give the salt 1 represented by the formula (B-2). 19 parts were obtained.

Identification of the compound represented by formula (B-2);
MS (ESI (+) Spectrum): M ⁺ 279.1
MS (ESI (−) Spectrum): M ^- 733.0

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

式（Ｂ−１−ａ）で表される塩２．００部及びペンタフルオロプロピオン酸無水物６．０５部を仕込み、１２０℃で１５時間攪拌後、２３℃まで冷却した。得られた反応物に、クロロホルム１００部及び５％炭酸水素ナトリウム水溶液６６部を加えて２３℃で３０分間攪拌した後、分液した。回収された有機層に、イオン交換水５０部を仕込み、２３℃で３０分間攪拌した後、分液することにより有機層を回収した。この水洗の操作を４回行った。回収された有機層を濃縮し、得られた濃縮物に、ｔｅｒｔ−ブチルメチルエーテル５０部を加えて２３℃で３０分間攪拌した後、ろ過することにより、式（Ｂ−３）で表される塩１．４６部を得た。

2.00 parts of the salt represented by the formula (B-1-a) and 6.05 parts of pentafluoropropionic anhydride were charged, stirred at 120 ° C. for 15 hours, and then cooled to 23 ° C. To the obtained reaction product, 100 parts of chloroform and 66 parts of 5% aqueous sodium hydrogen carbonate solution were added and stirred at 23 ° C. for 30 minutes, followed by liquid separation. The recovered organic layer was charged with 50 parts of ion exchanged water, stirred at 23 ° C. for 30 minutes, and then separated to recover the organic layer. This washing operation was performed 4 times. The collected organic layer is concentrated, 50 parts of tert-butyl methyl ether is added to the resulting concentrate, and the mixture is stirred at 23 ° C. for 30 minutes, followed by filtration, which is represented by the formula (B-3). 1.46 parts of salt were obtained.

Identification of the compound represented by formula (B-3);
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 633.0

Example 4: Synthesis of salt represented by formula (B-4)

式（Ｂ−１−ａ）で表される塩２．００部及びトリフルオロ酢酸無水物３．１０部を仕込み、１２０℃で１５時間攪拌後、２３℃まで冷却した。得られた反応物に、クロロホルム１００部及び５％炭酸水素ナトリウム水溶液６６部を加えて２３℃で３０分間攪拌した後、分液した。回収された有機層に、イオン交換水５０部を仕込み、２３℃で３０分間攪拌した後、分液することにより有機層を回収した。この水洗の操作を４回行った。回収された有機層を濃縮し、得られた濃縮物に、ｔｅｒｔ−ブチルメチルエーテル５０部を加えて２３℃で３０分間攪拌した後、ろ過することにより、式（Ｂ−４）で表される塩０．７８部を得た。

2.00 parts of the salt represented by the formula (B-1-a) and 3.10 parts of trifluoroacetic anhydride were charged, stirred at 120 ° C. for 15 hours, and then cooled to 23 ° C. To the obtained reaction product, 100 parts of chloroform and 66 parts of 5% aqueous sodium hydrogen carbonate solution were added and stirred at 23 ° C. for 30 minutes, followed by liquid separation. The recovered organic layer was charged with 50 parts of ion exchanged water, stirred at 23 ° C. for 30 minutes, and then separated to recover the organic layer. This washing operation was performed 4 times. The recovered organic layer is concentrated, 50 parts of tert-butyl methyl ether is added to the resulting concentrate, and the mixture is stirred at 23 ° C. for 30 minutes, followed by filtration, which is represented by the formula (B-4). 0.78 part of salt was obtained.

Identification of the compound represented by formula (B-4);
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 533.0

Example 5: Synthesis of salt represented by formula (B-5)

式（Ｂ−５−ａ）で表される塩２．１４部及びヘプタフルオロ酪酸無水物８．００部を仕込み、１２０℃で１５時間攪拌後、２３℃まで冷却した。得られた反応物に、クロロホルム１００部及び５％炭酸水素ナトリウム水溶液６６部を加えて２３℃で３０分間攪拌した後、分液した。回収された有機層に、イオン交換水５０部を仕込み２３℃で３０分間攪拌した後、分液することにより有機層を回収した。この水洗の操作を４回行った。回収された有機層を濃縮し、得られた濃縮物に、ｔｅｒｔ−ブチルメチルエーテル５０部を加えて２３℃で３０分間攪拌した後、ろ過することにより、式（Ｂ−５）で表される塩１．８８部を得た。

2.14 parts of the salt represented by the formula (B-5-a) and 8.00 parts of heptafluorobutyric anhydride were charged, stirred at 120 ° C. for 15 hours, and then cooled to 23 ° C. To the obtained reaction product, 100 parts of chloroform and 66 parts of 5% aqueous sodium hydrogen carbonate solution were added and stirred at 23 ° C. for 30 minutes, followed by liquid separation. The recovered organic layer was charged with 50 parts of ion exchange water, stirred at 23 ° C. for 30 minutes, and then separated to recover the organic layer. This washing operation was performed 4 times. The recovered organic layer is concentrated, 50 parts of tert-butyl methyl ether is added to the resulting concentrate, and the mixture is stirred at 23 ° C. for 30 minutes, followed by filtration, which is represented by the formula (B-5). 1.88 parts of salt were obtained.

Identification of the compound represented by formula (B-5);
MS (ESI (+) Spectrum): M ⁺ 305.1
MS (ESI (−) Spectrum): M ^- 733.0

The monomers used are shown below.

Synthesis Example 1: Synthesis of Resin A1 Monomer represented by Formula (A), Monomer represented by Formula (E), Monomer represented by Formula (B), Monomer represented by Formula (C) and Formula ( The monomer represented by D) was charged at a molar ratio of 30: 14: 6: 20: 30. Subsequently, 1.5 mass times dioxane was added with respect to the total mass of all the monomers. Into the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were respectively added to 1.00 mol% and 3.00 mol% with respect to the total number of moles of all monomers. And heated at 75 ° C. for about 5 hours. Thereafter, the reaction solution is purified by pouring it into a large amount of methanol / water mixed solvent (4: 1) and precipitating three times, and the weight average molecular weight is about 7.2 × 10 ^3. The coalescence was obtained with a yield of 78%. This copolymer has a structural unit of the following formula, and this is designated as resin A1.

Synthesis Example 2: Synthesis of Resin A2 A monomer represented by formula (A), a monomer represented by formula (B), and a monomer represented by formula (C) were charged in a molar ratio of 50:25:25. Then, 1.5 mass times dioxane was added with respect to the total mass of all the monomers. To the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) were added as initiators in proportions of 1 mol% and 3 mol%, respectively, with respect to the total number of moles of all monomers. This was heated at 77 ° C. for about 5 hours. Thereafter, the reaction solution is purified by pouring it into a large amount of methanol / water mixed solvent (3: 1) and precipitating three times, and the weight average molecular weight is about 8.0 × 10 ^3. The coalescence was obtained in 60% yield. This copolymer has a structural unit of the following formula, and this is designated as resin A2.

  As shown in Table 1, a resist composition was prepared by filtering a mixture obtained by mixing and dissolving the following components through a fluororesin filter having a pore size of 0.2 μm.

Ｂ２：式（Ｂ−２）で表される塩

Ｂ３：式（Ｂ−３）で表される塩

Ｂ４：式（Ｂ−４）で表される塩

Ｂ５：式（Ｂ−５）で表される塩

Ｘ１：式（Ｘ１）で表される塩

<Resin>
A1: Resin A1 obtained in Synthesis Example 1
A2: Resin A2 obtained in Synthesis Example 2
<Acid generator>
B1: Salt represented by the formula (B-1)

B2: salt represented by formula (B-2)

B3: salt represented by formula (B-3)

B4: salt represented by formula (B-4)

B5: salt represented by formula (B-5)

X1: Salt represented by the formula (X1)

<Basic compound: Quencher>
C1: 2,6-diisopropylaniline <solvent>
Propylene glycol monomethyl ether acetate 265 parts 2-heptanone 20.0 parts Propylene glycol monomethyl ether 20.0 parts γ-butyrolactone 3.5 parts

An organic antireflective coating composition (ARC-29; manufactured by Nissan Chemical Co., Ltd.) is applied to a silicon wafer and baked at 205 ° C. for 60 seconds to form an organic antireflective coating having a thickness of 78 nm. Formed.
Subsequently, the resist composition was spin-coated on the organic antireflection film so that the film thickness after pre-baking was 85 nm.

After applying the resist composition, the obtained silicon wafer was pre-baked (PB) for 60 seconds at a temperature shown in the PB column of Table 1 on a direct hot plate. Using the ArF excimer laser stepper [FPA5000-AS3; manufactured by Canon Inc., NA = 0.75, 2 / 3Annular] on the silicon wafer on which the resist composition film is formed in this manner, the exposure amount is changed stepwise. The line and space pattern was exposed.
After exposure, post-exposure baking (PEB) is performed for 60 seconds on a hot plate at the temperature shown in the PEB column of Table 1, and then paddle development is performed for 60 seconds with an aqueous 2.38 mass% tetramethylammonium hydroxide solution. A resist pattern was obtained.

  Resolution evaluation: A resist pattern formed by exposing the 100 nm line-and-space pattern with an exposure amount of 1: 1 is observed with a scanning electron microscope, and a resolution of 85 nm is obtained (in particular, 80 nm )), And those not resolved x.

Line edge roughness evaluation (LER): The wall surface of the obtained resist pattern was observed with a scanning electron microscope, and when the fluctuation width of the unevenness on the side wall of the resist pattern was 8 nm or less, ○, and when it exceeded 8 nm, × .
These results are shown in Table 2.

  According to the salt of the present invention, a pattern having excellent resolution and line edge roughness can be formed using a resist composition containing the salt.

Claims (6)

A salt represented by the formula (I).

[In Formula (I), W ¹ represents a saturated hydrocarbon ring having 3 to 36 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon ring may be substituted with an alkyl group having 1 to 6 carbon atoms. And —CH ₂ — contained in the saturated hydrocarbon ring may be replaced by —O—, —SO ₂ — or —CO—.
L ¹ represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, a hydrogen atom contained in the divalent saturated hydrocarbon group may be substituted with a fluorine atom, and the divalent —CH ₂ — contained in the saturated hydrocarbon group may be replaced by —O— or —CO—.
R ¹ and R ² each independently represents a C 1-6 alkyl group which may have a fluorine atom.
R ³ and R ⁴ each independently represents a fluorine atom or a C 1-6 perfluoroalkyl group.
Z ⁺ represents an organic cation. ] The salt according to claim 1 represented by formula (II).

[In Formula (II), L ¹ , R ¹ , R ² , R ³ , R ⁴ and Z ⁺ represent the same meaning as described above. ]   The acid generator containing the salt of Claim 1 or 2.   A resin comprising an acid generator according to claim 3 and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, and is dissolved in the alkaline aqueous solution by the action of the acid. A resist composition which is a resin to be obtained.   The resist composition according to claim 4, further comprising a basic compound. (1) The process of apply | coating the resist composition of Claim 4 or 5 on a board | substrate,
(2) a step of removing the solvent from the composition after coating to form a composition layer;
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) A pattern forming method including a step of developing the heated composition layer using a developing device.