Reaction Mechanisms of Brominated Chemically Amplified Resists

Abstract

Poly(4-hydroxystyrene) (PHS) and its derivatives are widely-used base polymers for chemically amplified resists. Halogenation of polymers is a popular strategy to improve resist performance. However, the reaction mechanisms for halogenated PHS have not been investigated. We investigated the reaction mechanisms for brominated PHS from the viewpoint of acid generation. We found that brominated PHS without acid generators can produce acids with 55% efficiency compared with PHS with 3.1 mol % (10 wt %) triphenylsulfonium triflate. The acid yield of brominated PHS was twice that of poly(4-bromostyrene).