Sulfonium salt, chemically amplified resist composition, and pattern forming process

A sulfonium salt having the general formula (1):

• wherein R0 is hydrogen, or a straight C1-C20 or branched or cyclic C3-C20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom,
• R01 and R02 are each independently hydrogen, or a straight C1-C20 or branched or cyclic C3-C20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, or R01 and R02 may bond together to form a ring with the carbon atom to which they are attached, with the proviso that at least one of R0, R01 and R02 has a cyclic structure,
• L is a single bond or forms an ester bond, sulfonate bond, carbonate bond or carbamate bond with the vicinal oxygen atom,
• R2, R3 and R4 are each independently a straight C1-C20 or branched or cyclic C3-C20 monovalent hydrocarbon group which may be substituted with or separated by a heteroatom, at least two of R2, R3 and R4 may bond together to form a ring with the sulfur atom in the formula.