METAL-FREE ACID GENERATORS FOR CHEMICALLY AMPLIFIED MONODISPERSAL POLYHYDROXYSTYRENE-BASED POSITIVE RESIST AND POSTEXPOSURE DELAY PROBLEM

Our studies of metal-free acid generators (AG) for chemically amplifie d monodispersal PHS-based positive resist (MDPR) show that bis(t-butyl phenyl)iodonium triflate (BBITf) is the most promising for practical u se. It inhibits dissolution strongly before exposure and weakly after post-exposure baking. A 0.25-mu m 1&s pattern can be fabricated by KrF excimer laser lithography using MDPR with a BBITf acid generator. MDP R is highly susceptible to contamination from the air, as are other ch emically amplified resists. Adding an organic base to MDPR is very eff ective in improving stability against airborne contamination, but at t he expense of sensitivity.