Synthesis and lithographic charaterization of poly(hydroxystyrene-co-t-butylacrylate-co-3- (butoxycarbonyl)-N-vinyl caprolactam)

Abstract

Most of positive chemical amplification resists do not have enough stability to process delay. It has been claimed that airborne contaminations neutralize acids from photoacid generaters. Our new environmentally stable chemical amplification positive resist has designed on the basis of concept of using basic additives without any migration throughout the process. The resist system consists of triphenylsulfonium hexafluoroantimonate as photoacidgenerator and poly(hydroxystyrene-co-t-butyl acrylate-co-3- (t-butoxycarbonyl)-N-vinyl caprolactam). And poly(hydroxystyrene-co-t- butyl acrylate) was also prepared as reference matrix polymer in order to verify the improvement of environmental stability of the new resist system containing the basic unit, as acid scavanger. Characterization of the resist terpolymer and copolymer was performed by using proton NMR, FT-IR spectrometer, DSC, and TGA. The chmical changes of resist system due to deep UV irradition were studied using TGA, UV, and FT-IR spectrometer. The lowering of deep UV sensitivity of resist polymers show that BCVC unit satisfies the requirement for the trapping of photogenerated acid. We obtained 1 micrometer line/space positive images patterns. We knew that the new resist system has desirable properties such as high transparency in deep UV region, facile deprotection, proper sensitivity. And we expect improvement of environmental stability by basic unit. This system can be applied to high temperature process without migration of basic additives.