Environmentally stable chemical amplification positive resist: principle, chemistry, contamination resistance, and lithographic feasibility.

Abstract

Yor•ktoWf HeicThts, Neli' York 10598, ii. S. a. Our new environmentally stable chemical amplification positive resici named ESCAP is described, which has been designed on the basis of our annealing concept for contamination resistance. The ESCAP resist consists of a copolymer of 4-hydroxystyrene with t-hutyl acrylate and N-ca mphorsulfonyloxynaphthalimide as a nonionic organic acid generator. In contrastt to other positive chemical amplification resist systems, the ESCAP resist film can he heated above its glass transition temperature of ~I5() r'C without premature thermal degradation of the protecting group, thus allowing good annealing and reduction of the free volume. In consequence, the ESCAP resist which employs unconventionally high prehake temperature of '-l50`'l50`'C ahsorhs N-methylpyrrolidone at a dramatically reduced rate and is extremely insensitive to the delay effect. The ESCAP resist has successfully demonstrated 0.25 um resolution on K rF excimer laser steppers and on a Micrascan system at a dose range of 30-40 mJ/cm2.