Approach toward environmental stabilization of chemical amplification resists.

Abstract

A molecular design for stabilization of chemical amplification resists toward airborne contamination is described, which is based on our observation that glass transition temperatures (Tg) primarily govern the absorption of N-methylpyrrolidone (NMP) vapor in thin polymer films. Employing the meta-isomer (T g = 85 C) of poly(t-butoxycarbonyloxystyrene) (PBOCST) to replace the para-isomer (T g =130 C) in the IBM's tBOC resist has proved the validity of our T g theory in NMP uptake measurements as well as in negative lithographic imaging. Furthermore, the use of a meta-isomer to lower T g for better annealing has been shown to be also useful in decreasing NMP absorption in aqueous base developable,, positive copolymer resists, providing f increased contamination resistance.