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

A salt represented by a formula (I),

• wherein Q1, Q2, R1, and R2 each independently represent a hydrogen atom, a fluorine atom, a perfluoroalkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms,
• z represents an integer of 0 to 6, and when z is 2 or more, a plurality of R1 and R2 may be same or different from each other,
• X0 represents a single bond, or a group formed by —O—, —CO—, —S—, —SO—, —SO2—, —NR7—, or a combination thereof,
• mm1 represents 0 or 1,
• L1 and L2 each independently represent a single bond or a hydrocarbon group having 1 to 28 carbon atoms and optionally having a substituent, and —CH2— included in the hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• R7 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
• W1 represents a single bond or a cyclic hydrocarbon group having 3 to 36 carbon atoms and optionally having a substituent, and —CH2— included in the cyclic hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• A1 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group may have a substituent, and —CH2— included in the hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• R3 represents an acid stable hydrocarbon group optionally having a substituent,
• R4 represents a halogen atom, a cyano group, a nitro group, or a hydrocarbon group having 1 to 18 carbon atoms, the hydrocarbon group may have a substituent, and —CH2— included in the hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• m2 represents an integer of 0 to 3, and when m2 is 2 or more, a plurality of R4 may be same or different from each other,
• X1 represents a single bond, or —O—, —CO—, —S—, —SO—, —SO2—, —NR7—, a phenylene group optionally having a substituent, or a group obtained by combining these groups,
• R0 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms and optionally having a halogen atom, and
• ZI+ represents an organic cation.

A resin comprising a structural unit represented by a formula (IP), wherein

• Q1, Q2, R1, and R2 each independently represent a hydrogen atom, a fluorine atom, a perfluoroalkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms,
• z represents an integer of 0 to 6, and when z is 2 or more, a plurality of R1 and R2 may be same or different from each other,
• X0 represents a single bond, or a group formed by —O—, —CO—, —S—, —SO—, —SO2—, —NR7—, or a combination thereof,
• mm1 represents 0 or 1,
• L1 and L2 each independently represent a single bond or a hydrocarbon group having 1 to 28 carbon atoms and optionally having a substituent, and —CH2— included in the hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• R7 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
• W1 represents a single bond or a cyclic hydrocarbon group having 3 to 36 carbon atoms and optionally having a substituent, and —CH2— included in the cyclic hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• A1 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group may have a substituent, and —CH2— included in the hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• R3 represents an acid stable hydrocarbon group optionally having a substituent,
• R4 represents a halogen atom, a cyano group, a nitro group, or a hydrocarbon group having 1 to 18 carbon atoms, the hydrocarbon group may have a substituent, and —CH2— included in the hydrocarbon group may be substituted with —O—, —S—, —SO2—, —SO—, —NR7—, or —CO—,
• m2 represents an integer of 0 to 3, and when m2 is 2 or more, a plurality of R4 may be same or different from each other,
• X1 represents a single bond, or —O—, —CO—, —S—, —SO—, —SO2—, —NR7—, a phenylene group optionally having a substituent, or a group obtained by combining these groups,
• R0 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms and optionally having a halogen atom, and
• ZI+ represents an organic cation.