Negative Photoresists Based on Cholic Acid Methacrylate Copolymerized with Methacrylates with 1,3-Dioxolane and 1,3-Dioxane Rings as Crosslinkers

Abstract

Copolymers of methacrylate derivatives with pendant hydroxy alicyclic acid moiety and cyclic acetal moieties, poly (2-[1,3]dioxolan-2-yl-ethyl methacrylate-co-cholic acid methacrylate) and poly (2-[1,3]dioxan-2-yl-ethyl methacrylate-co-cholic acid methacrylate), were studied for 193 nm negative photoresists. Cholic acid was introduced in order to improve etching and swelling resistances, and to impart crosslinking functionality. Cyclic acetal moieties were used as crosslinkers. The negative resists didn’t show swelling phenomena in the aqueous base developer and gave high resolution patterns.