Patent ID: 8530137

Claim:
A photoresist composition comprising a sulfonium salt having an anion represented by the formula (IA): wherein R 1 and R 2 independently represent a C1-C12 aliphatic hydrocarbon group, a C3-C20 saturated cyclic hydrocarbon group, a C6-C20 aromatic hydrocarbon group or a C7-C21aralkyl group, and the aliphatic hydrocarbon group, the saturated cyclic hydrocarbon group, the aromatic hydrocarbon group and the aralkyl group can have one or more substituents selected from the group consisting of a hydroxyl group, a cyano group, a fluorine atom, a trifluoromethyl group and a nitro group, and one or more —CH 2 —in the aliphatic hydrocarbon group can be replaced by —O—or —CO—, or R 1 and R 2 are bonded each other to form a C4-C20 nitrogen-containing ring together with the nitrogen atom to which they are bonded, an acrylic resin having an acid-labile group and being insoluble or poorly soluble in an aqueous alkali solution but becoming soluble in an aqueous alkali solution by the action of an acid, and an acid generator.