A NOVEL SILICON-CONTAINING COPOLYMER FOR NEAR-UV RESIST

N-(4-hydroxyphenyl)maleimide/allyltrimethylsilane copolymer (PHAMS) was synthesized as a novel near-u.v. resist when containing diazonaphthoquinone sulphonate chloride. The chain-stiffening effect of the cyclic maleimide group was responsible for high temperature stability A high glass transition temperature of 226-degrees and a thermal decomposition temperature of 418-degrees were found for PHAMS; a well-defined melting point was not observed because of its low crystallinity. The prepared resist could produce high contrast images at dose of 42.4 mJ/cm2. Microlithographic positive images were obtained stable to temperatures above 200-degrees. Excellent solubility in aqueous base was observed with PHAMS having 9.3 wt% silicon content and an oxygen-plasma etching rate of 1:10.5 compared to that of hard-baked HPR-204 (believed to be a novolac-type resin; baked at 200-degrees for 30 min as a coating on silicon wafer).