Sulfonium salt compound, method for producing the same, and photoacid generator

1. A sulfonium salt compound represented by the following general formula (I):

wherein R 1 and R 2 each denote the same or a different alkyl group having 1 to 18 carbon atoms, R 3 and R 4 each denote the same or a different alkyl group having 1 to 10 carbon atoms, and X − denotes a sulfone imide anion or a perfluoroalkanesulfonic acid anion represented by the formula (IV):

R 8 —SO 3 −   (IV),

wherein R 8 denotes an alkyl group having 2 to 4 carbon atoms in which all hydrogen atoms are substituted by fluorine atoms, and

wherein the substituents denoted by R 3 O and R 4 O are each located at an arbitrary position selected from the 2-position to the 8-position of the naphthyl group.

2. The sulfonium salt compound according to claim 1 , wherein

R 1 and R 2 each denote the same or a different alkyl group having 1 to 8 carbon atoms, and

R 3 and R 4 each denote the same or a different alkyl group having 1 to 8 carbon atoms.

3. The sulfonium salt compound according to claim 1 , wherein

X − denotes a sulfone imide anion represented by the following general formula (II) or

where R 5 and R 6 each denote the same or a different alkyl group having 1 to 6 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom; or

where R 7 denotes an alkylene group having 2 to 5 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom.

4. The sulfonium salt compound according to claim 3 , wherein

R 5 and R 6 each denote the same or a different alkyl group having 1 to 4 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom.

5. The sulfonium salt compound according to claim 3 , wherein

R 7 denotes an alkylene group having 3 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom.

6. A photoacid generator containing the sulfonium salt compound according to claim 1 .

7. A method for producing a sulfonium salt compound, comprising:

Step (a) of subjecting, to dehydration condensation, a sulfoxide compound represented by the following general formula (V):

where R 1 and R 2 each denote the same or a different alkyl group having 1 to 18 carbon atoms, and a naphthalene compound represented by the following formula (VI):

where R 3 and R 4 each denote the same or a different alkyl group having 1 to 10 carbon atoms, wherein the substituents denoted by R 3 O and R 4 O are each located at an arbitrary position selected from the 2-position to the 8-position of the naphthyl group; and

Step (b) of producing a sulfonium salt compound represented by the following general formula (I):

where R 1 and R 2 each denote the same substituent as defined in the aforementioned general formula (V), R 3 and R 4 each denote the same substituent as defined in the aforementioned general formula (VI), and X − denotes the same substituent as defined in the general formula X − Y + , by reaction between a dehydrated condensate obtained by the dehydration condensation in Step (a) and a salt compound or an acid compound represented by a general formula X − Y + , where X − is represented by the following general formula (II), (III), or (IV), and Y + denotes an alkali metal ion or a hydrogen ion:

where R 5 and R 6 each denote the same or a different alkyl group having 1 to 6 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom;

where R 7 denotes an alkylene group having 2 to 5 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom; or

R 8 —SO 3 −   (IV),

where R 8 denotes an alkyl group having 2 to 4 carbon atoms in which all hydrogen atoms are substituted by fluorine atoms.