Photoacid generator, method for producing the same, and resist composition comprising the same

A method for producing a photoacid generator, the method comprising:

• a first step of allowing a hydroxysulfonic acid salt to react with oxirane, and thereby producing a hydroxyethoxysulfonic acid salt;
• a second step of allowing the hydroxyethoxysulfonic acid salt produced above to react with a carbonyl halide and thereby producing an intermediate;
• and
• a third step of subjecting the intermediate thus produced to a substitution reaction of the cation, and thereby producing a compound represented by the following formula (1):
• wherein in the formula (1),
• Y1 and Y2 each independently represent any one selected from the group consisting of a cycloalkyl group, a heterocycloalkyl group, an aryl group and a heteroaryl group;
• X represents any one selected from the group consisting of an alkanediyl, an alkenediyl, NR′, S, O, CO and combinations thereof;
• R′ represents any one selected from the group consisting of a hydrogen atom and an alkyl group;
• R1 and R2 each independently represent any one selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a perfluoroalkyl group, a perfluoroalkoxy group, a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an amino group and a thio group;
• n1 represents an integer or 1 or 2;
• n2 represents an integer from 0 to 5;
• and
• A+ represents an organic counterion.