Sulfonium compound, photoacid generator, and resist composition

1. A sulfonium compound having two acid sites, each respectively having an acid generator that is different from the other, and represented by the following formula (1):

wherein in the formula (1),

X represents an electron donor group;

R 1 and R 2 each independently represent any one selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, a heteroalkyl group, a heterocycloalkyl group and a heteroaryl group, or R 1 and R 2 may be joined, together with the sulfur atom to which R 1 is bonded, to form a heterocycloalkyl group having 2 to 7 carbon atoms;

R 4 to R 6 each independently represent any one selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, a heteroalkyl group, a heterocycloalkyl group, and a heteroaryl group, or R 4 and R 5 may be joined, together with the sulfur atom to which R 4 is bonded, to form a heterocycloalkyl group having 2 to 7 carbon atoms;

R 3 represents any one selected from the group consisting of a cyclic alkenediyl group, a heterocyclic alkenediyl group, an arylene group and a heteroarylene group; and

A represents an anion.

2. The sulfonium compound according to claim 1 , wherein A represents any one of the group consisting of a sulfonate anion, an imide anion, a methide anion, a halogenated alkyl anion, a carboxylate anion, an iodonium anion and a sulfonylimide anion.

3. The sulfonium compound according to claim 1 , wherein −A represents any one selected from the group consisting of anions represented by the following formula (1-1), (1-2) and (1-3):

wherein in the formula (1-1),

Q 1 , Q 2 , Q 3 and Q 4 each independently represent any one selected from the group consisting of a hydrogen atom, a halogen atom and an alkyl group;

Y 1 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;

Y 2 represents any one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, a heteroalkyl group, an allyl group, a perfluoroalkyl group, a haloalkyl group, and an alkylsulfonyl group;

n represents an integer from 0 to 10, m represents an integer from 0 to 10, and l represents an integer from 0 to 5;

wherein in the formula (1-2),

Y 3 and Y 4 each independently represent any one selected from the group consisting of an alkanediyl, an alkenediyl, NR′, S, O, CO, O 2 S and combinations thereof, R′ represents any one selected from the group consisting of a hydrogen atom and an alkyl group;

Y 5 and Y 6 each independently represent any one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, a heteroalkyl group, an allyl group, a perfluoroalkyl group, a haloalkyl group, and an alkylsulfonyl group;

o represents an integer from 0 to 5, and p represents an integer from 0 to 5; and

wherein in the formula (1-3),

Y 7 , Y 8 and Y 9 each independently represent any one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, a heteroalkyl group, an allyl group, a perfluoroalkyl group, a haloalkyl group and an alkylsulfonyl group.

4. The sulfonium compound according to claim 1 , wherein −A represents any one selected from the group consisting of —OSO 2 CF 3 , —OSO 2 C 4 F 9 , —OSO 2 C 8 F 17 , —N(CF 3 ) 2 , —N(C 2 F 5 ) 2 , —N(C 4 F 9 ) 2 , —C(CF 3 ) 3 , —C(C 2 F 5 ) 3 , —C(C 4 F 9 ) 3 and an anion represented by the following formula (1-4):

wherein in the formula (1-4),

Y 10 represents any one selected from the group consisting of a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an alkyl group, a heteroalkyl group, an allyl group, a perfluoroalkyl group, a haloalkyl group and an alkylsulfonyl group;

R 11 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;

R 12 and R 13 each independently represent any one selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 8 carbon atoms;

r represents an integer from 0 to 5; and

Q 5 and Q 6 each independently represent a halogen atom.

5. The sulfonium compound according to claim 1 , wherein R 3 represents any one selected from the group consisting of groups represented by the following formulas (2-1) to (2-4):

wherein in the formulas (2-1) to (2-4),

R 21 and R 22 each independently represent any one selected from the group consisting of a single bond, an alkanediyl having 1 to 5 carbon atoms, and an alkenediyl having 2 to 5 carbon atoms; and

R 23 represents any one selected from the group consisting of —CH 2 —, —O— and —S—.

6. The sulfonium compound according to claim 1 , wherein X represents any one selected from the group consisting of —O—, —S—, —O—(CH 2 ) n —O— (wherein n represents an integer from 1 to 5), —(CH 2 ) n —S— (wherein n represents an integer from 1 to 5), and a group represented by the following formula (3-1):

wherein in the formula (3-1),

R 31 and R 32 each independently represent any one selected from the group consisting of —O—, —S— and combinations thereof.

7. The sulfonium compound according to claim 1 , wherein the sulfonium compound represented by the formula (1) is any one selected from the group consisting of compounds represented by the following formula (5-1) to formula (5-3):

wherein in the formulas (5-1) to (5-3),

R 51 and R 52 each independently represent any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a halogenated alkyl group having

1 to 5 carbon atoms;

n51 and n52 each independently represent an integer from 1 to 5;

n53 and n54 each independently represent an integer from 0 to 10;

R 3 represents any one selected from the group consisting of a cycloalkenediyl group, a heterocyclic alkenediyl group, an arylene group and a heteroarylene group;

X represents an electron donor group;

R 4 to R 6 each independently represent any one selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, a heteroalkyl group, a heterocycloalkyl group, and a heteroaryl group, or R 4 and R 5 may be joined, together with the sulfur atom to which R 4 is bonded, to form a heterocycloalkyl group having 2 to 7 carbon atoms; and

−A represents an anion.