NEW ONIUM SALT AND POSITIVE TYPE PHOTORESIST MATERIAL USING THE SAME

摘要

PURPOSE:To provide a new compound which is useful as a fine processing positive type resist material which has high sensitivity to far ultraviolet rays, electron rays and X-rays and has optically high resolution. CONSTITUTION:A salt of the formula: (R)3S<+>M (Rs are aromatic groups; at least one of Rs is t-alkoxy-substituted phenyl; M is anion for the sulfonium). Preferably a salt of formula I (R1 is tertiary lower alkyl; R2 is lower alkyl, alkoxy), for example, p-t-butoxytriphenylsulfonium triflate. The salt of formula I is obtained by cooling a solution of diphenyl sulfoxide in methylene chloride, pouring trimethylsilyl triflate to the cooled solution, heat-treating and stirring the mixture and adding a Grignard reagent prepared from p-t- butoxybromobenzene to effect reaction.