Salt, acid generator, resist composition and method for producing resist pattern

A salt represented by formula (I):

• wherein, in formula (I),
• R1, R2, R3 and R4 each independently represent a halogen atom or a perfluoroalkyl group having 1 to 6 carbon atoms,
• R5, R6 and R7 each independently represent a halogen atom, a hydroxy group, a fluorinated alkyl group having 1 to 6 carbon atoms or an alkyl group having 1 to 12 carbon atoms, and —CH2— included in the alkyl group may be replaced by —O— or —CO—,
• m5 represents an integer of 0 to 3, and when m5 is 2 or more, a plurality of R5 may be the same or different,
• m6 represents an integer of 0 to 3, and when m6 is 2 or more, a plurality of R6 may be the same or different,
• m7 represents an integer of 0 to 3, and when m7 is 2 or more, a plurality of R7 may be the same or different,
• R8 and R9 each independently represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and —CH2— included in the alkyl group may be replaced by —O— or —CO—, and
• AI− represents an anion represented by formula (I-A):
• wherein, in formula (I-A),
• Q1 and Q2 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms,
• L1 represents a group represented by any one of formula (b1-1) to formula (b1-3), and
• Y1 represents an alicyclic hydrocarbon group having 3 to 18 carbon atoms which may have a substituent, and —CH2— included in the alicyclic hydrocarbon group may be replaced by —O—, —SO2— or —CO—,
• wherein, in formula (b1-1) to formula (b1-3), * and ** represent a bonding site, and * represents a bonding site to —Y1,
• in formula (b1-1),
• Lb2 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen atom included in the saturated hydrocarbon group may be substituted with a fluorine atom,
• Lb3 represents a single bond or a divalent saturated hydrocarbon group having 2 to 22 carbon atoms, a hydrogen atom included in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and —CH2— included in the saturated hydrocarbon group may be replaced by —O— or —CO—, and
• the total number of carbon atoms of Lb2 and Lb3 is 22 or less;
• in formula (b1-2),
• Lb4 represents a single bond or a divalent saturated hydrocarbon group having 3 to 22 carbon atoms, and a hydrogen atom included in the saturated hydrocarbon group may be substituted with a fluorine atom,
• Lb5 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, a hydrogen atom included in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and —CH2— included in the saturated hydrocarbon group may be replaced by —O— or —CO—, and
• the total number of carbon atoms of Lb4 and Lb5 is 22 or less;
• in formula (b1-3),
• Lb6 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, a hydrogen atom included in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group,
• Lb7 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, a hydrogen atom included in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and —CH2— included in the saturated hydrocarbon group may be replaced by —O— or —CO—, and
• the total number of carbon atoms of Lb6 and Lb7 is 23 or less.

A salt represented by formula (I):

• wherein, in formula (I),
• R1, R2, R3 and R4 each independently represent a halogen atom or a perfluoroalkyl group having 1 to 6 carbon atoms,
• R5, R6 and R7 each independently represent a halogen atom, a hydroxy group, a fluorinated alkyl group having 1 to 6 carbon atoms or an alkyl group having 1 to 12 carbon atoms, and —CH2— included in the alkyl group may be replaced by —O— or —CO—,
• m5 represents an integer of 0 to 3, and when m5 is 2 or more, a plurality of R5 may be the same or different,
• m6 represents an integer of 0 to 3, and when m6 is 2 or more, a plurality of R6 may be the same or different,
• m7 represents an integer of 0 to 3, and when m7 is 2 or more, a plurality of R7 may be the same or different,
• R8 and R9 each independently represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and —CH2— included in the alkyl group may be replaced by —O— or —CO—, and
• AI− represents an anion represented by formula (I-A):
• wherein, in formula (I-A),
• Q1 and Q2 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms,
• L1 represents a saturated hydrocarbon group having 1 to 24 carbon atoms, and —CH2—included in the saturated hydrocarbon group may be replaced by —O— or —CO—, and the hydrogen atom included in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and
• Y1 represents a methyl group which has a substituent or an alicyclic hydrocarbon group having 3 to 18 carbon atoms which has a substituent, and —CH2— included in the alicyclic hydrocarbon group may be replaced by —O—, —SO2— or —CO—, and the substituent is at least one of a halogen atom, a hydroxy group, an alkyl group having 1 to 12 carbon atoms which may be substituted with a hydroxy group, an alicyclic hydrocarbon group having 3 to 16 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, an aralkyl group having 7 to 21 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, a glycidyloxy group, a —(CH2)ja—CO—O—Rb1 group and —(CH2)ja—CO—O—Rb1 group wherein Rb1 represents an alkyl group having 1 to 16 carbon atoms, an alicyclic hydrocarbon group having 3 to 16 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or groups obtained by combining these groups, ja represents an integer of 0 to 4, and —CH2—included in the alkyl group having 1 to 16 carbon atoms and the alicyclic hydrocarbon group having 3 to 16 carbon atoms may be replaced by —O—, —SO2— or —CO—.