Synthesis of photoresist using environmental-benign supercritical CO2 processes

Abstract

The requirement for a much finer line width circuits on semiconductors needs new developers such as supercritical fluid to prevent the collapse of the photoresist micro-patterns. The copolymers contain t-butyl methacrylate having an acid-cleavable t-butyl group and supercritical fluid CO2 soluble perfluorinated decyl methacrylate segments. The supercritical fluid CO2-philic properties of the photoresist changed to supercritical fluid CO2-phobic properties after the deprotection reaction by exposure, which made the exposed resist insoluble in the supercritical fluid CO2 developer. The synthesized copolymers containing more than 30% of perfluorinated decyl methacrylate were found to be soluble in supercritical fluid CO2. The variation of film thickness before and after exposure was largest when the mole ratio of perfluorinated decyl methacrylate in the copolymer was 30%.