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

Abstract

A sulfonium salt consisting of a sulfonium cation containing a pentafluorosulfanyl group and an acid labile group of tertiary / secondary ether structure, tertiary / secondary carbonate structure or acetal structure and an aromatic carboxylic acid anion is provided. A chemically amplified resist composition comprising the sulfonium salt as a quencher has a high sensitivity and resolution, and forms a resist film with improved lithography properties including LWR, CDU, EL and DOF as well as collapse resistance.z