Sulfonium salt, photo-acid generator, and photosensitive resin composition

1. A sulfonium salt represented by formula (1) described below:

wherein in formula (1), R 1 , R 2 , R 3 , R 5 and R 6 each independently represent an alkyl group, a hydroxy group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an arylthiocarbonyl group, an acyloxy group, an arylthio group, an alkylthio group, an aryl group, a heterocyclic hydrocarbon group, an aryloxy group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a hydroxy(poly)alkyleneoxy group, an optionally substituted amino group, a cyano group, a nitro group, or a halogen atom,

R 4 represents an alkyl group, a hydroxy group, an alkoxy group, an alkylcarbonyl group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, a heterocyclic hydrocarbon group, an an alkylsulfinyl group, an alkylsulfonyl group, a hydroxy(poly)alkyleneoxy group, an optionally substituted amino group, a cyano group, a nitro group, or a halogen atom,

m 1 to m 6 each represent the number of occurrences of each of R 1 to R 6 , m 1 , m 4 , and m 6 each represent an integer of 0 to 5, m 2 , m 3 , and m 5 each represent an integer of 0 to 4, and X − represents a monovalent polyatomic anion.

2. The sulfonium salt according to claim 1 , wherein R 1 to R 6 each independently represent one selected from the group consisting of a methyl group, a methoxy group, and an acetyl group.

3. The sulfonium salt according to claim 1 or 2 , wherein R 3 and R 4 are a methyl group or a methoxy group, m 3 and m 4 are 1, and m 1 , m 2 , m 5 , and m 6 are 0.

4. The sulfonium salt according to claim 1 , wherein m 1 to m 6 are all 0.

5. The sulfonium salt according to claim 1 , wherein X − is an anion represented by MY a − , (Rf) b PF 6-b − , R 10 c BY 4-c − , R 10 c GaY 4-c − , R 11 SO 3 − , (R 11 SO 2 ) 3 C − , or (R 11 SO 2 ) 2 N − (wherein M represents a phosphorus atom, a boron atom, an arsenic atom, or an antimony atom, Y represents a halogen atom, Rf represents an alkyl group, 80% by mole or more of whose hydrogen atoms are substituted with fluorine atoms, P represents a phosphorus atom, F represents a fluorine atom, R 10 represents a phenyl group, at least one of whose hydrogen atoms is substituted with a halogen atom, a trifluoromethyl group, a nitro group, or a cyano group, B represents a boron atom, Ga represents a gallium atom, R 11 represents an alkyl group having 1 to 20 carbon atoms, a perfluoroalkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, a represents an integer of 4 to 6, b represents an integer of 1 to 5, and c represents an integer of 1 to 4).

6. The sulfonium salt according to claim 1 , wherein X − is an anion represented by SbF 6 − , PF 6 − , BF 4 − , (CF 3 CF 2 ) 3 PF 3 − , (C 6 F 5 ) 4 B − , ((CF 3 ) 2 C 6 H 3 ) 4 B − , (C 6 F 5 ) 4 Ga − , ((CF 3 ) 2 C 6 H 3 ) 4 Ga − , trifluoromethanesulfonate anion, nonafluorobutanesulfonate anion, methanesulfonate anion, butanesulfonate anion, benzenesulfonate anion, or p-toluenesulfonate anion.

7. The sulfonium salt according to claim 1 , which is one selected from the group consisting of [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsolfonium tris(pentafluoroethyl)trifluorophosphate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium tetrakis(pentafluorophenyl)borate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium hexafluoroantimonate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium hexafluorophosphate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium trifluoromethanesulfonate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium nonafluorobutanesulfonate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium methanesulfonate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium butanesulfonate, and [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium p-toluenesulfonate.

8. A photo-acid generator, comprising the sulfonium salt according to claim 1 .