3  US 9,221,742 B2  4  In one aspect, the invention provides a sulfonium salt hav› ing the general formula (1 ).  Herein R 0  is hydrogen, or a straight C$_{1}$-C$_{20 }$ or branched or  cyclic C$_{3}$-C$_{20 }$monovalent hydrocarbon group which may be  substituted with or separated by a heteroatom; R$^{O 1 }$and R $^{02 }$are  each independently hydrogen, or a straight C$_{1 }$-C$_{20 }$ or  branched or cyclic C$_{3 }$-C$_{20 }$ monovalent hydrocarbon group  which may be substituted with or separated by a heteroatom,  or R 01  and R$^{02 }$may bond together to form a ring with the  carbon atom to which they are attached, with the proviso that  at least one ofR 0 , R $^{01 }$and R$^{02 }$has a cyclic structure; Lis a  single bond or forms an ester bond, sulfonate bond, carbonate  bond or carbamate bond with the vicinal oxygen atom; R  2 , R 3  and R$^{4 }$are each independently a straight C$_{1 }$-C$_{20 }$or branched  or cyclic C$_{3}$-C$_{20 }$monovalent hydrocarbon group which may  be substituted with or separated by a heteroatom, at least two  ofR 2 , R 3  and R 4  may bond together to form a ring with the  sulfur atom in the formula.  In a preferred embodiment, the anion moiety of the for- mula:  is selected from the following formulae (A-9) to (A-16),  (A-27) to (A-34), (A-44) to (A-50), (A-52), and (A-53).  -continued  (1)  (A-9)  (A-10)  0  o  ):c~  (A-12)  lGy):m,  (A-13)  )(fy):m,  (A-14)  (A-15)  (A-16)  (A-27)  (A-28)  (A-29) 