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

A salt represented by formula (I):

• wherein, in formula (I),
• R1, R2 and R3 each independently represent a hydroxy group, *—O—R10, *—O—CO—O—R10 or *—O-L10-CO—O—R10, and * represents a bonding site to the benzene ring,
• L10 represents an alkanediyl group having 1 to 6 carbon atoms,
• R10 represents a group represented by formula (1a) or a group represented by formula (2a),
• R4, R5, R6, R7, R8 and R9 each independently represent a halogen atom, a haloalkyl group having 1 to 12 carbon atoms or a hydrocarbon group having 1 to 18 carbon atoms, the hydrocarbon group may have a substituent, and —CH2— included in the haloalkyl group and the hydrocarbon group may be replaced by —O—, —S—, —CO— or —SO2—,
• A1, A2 and A3 each independently represent a hydrocarbon group having 2 to 20 carbon atoms, the hydrocarbon group may have a substituent, and —CH2— included in the hydrocarbon group may be replaced by —O—, —CO—, —S— or —SO2—,
• m1 represents an integer of 0 to 5, and when m1 is 2 or more, a plurality of groups in parentheses may be the same or different from each other,
• m2 represents an integer of 0 to 4, and when m2 is 2 or more, a plurality of groups in parentheses may be the same or different from each other,
• m3 represents an integer of 0 to 4, and when m3 is 2 or more, a plurality of groups in parentheses may be the same or different from each other,
• m4 represents an integer of 0 to 4, and when m4 is 2 or more, a plurality of R4 may be the same or different from each other,
• m5 represents an integer of 0 to 4, and when m5 is 2 or more, a plurality of R5 may be the same or different from each other,
• m6 represents an integer of 0 to 4, and when m6 is 2 or more, a plurality of R6 may be the same or different from each other,
• m7 represents an integer of 0 to 5, and when m7 is 2 or more, a plurality of R7 may be the same or different from each other,
• m8 represents an integer of 0 to 4, and when m8 is 2 or more, a plurality of R8 may be the same or different from each other,
• m9 represents an integer of 0 to 4, and when m9 is 2 or more, a plurality of R9 may be the same or different from each other,
• in which 0≤m1+m7≤5, 0≤m2+m8≤4, 0≤m3+m9≤4, and at least one of m1, m2 and m3 represents an integer of 1 or more,
• X4 represents a single bond, —CH2—, —O—, —S—, —CO—, —SO— or —SO2—, and
• AI− represents an organic anion,
• wherein, in formula (1a), Raa1, Raa2 and Raa3 each independently represent an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group obtained by combining these groups, or Raa1 and Raa2 may be bonded to each other to form an alicyclic hydrocarbon group having 3 to 20 carbon atoms together with carbon atoms to which Raa1 and Raa2 are bonded, and
• * represents a bonding site:
• wherein, in formula (2a), Raa1′ and Raa2′ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, Raa3′ represents a hydrocarbon group having 1 to 20 carbon atoms, or Raa2′ and Raa3′ may be bonded to each other to form a heterocyclic group having 3 to 20 carbon atoms together with —C—Xa— to which Raa2′ and Raa3′ are bonded, and —CH2— included in the hydrocarbon group and the heterocyclic group may be replaced by —O— or —S—,
• Xa represents an oxygen atom or a sulfur atom, and
• * represents a bonding site.