A novel water developable photoresist for deep UV lithography

Abstract

Poly(3-(t-butoxycarbonyl)-1-vinyl-2-pyrrolidinone) (PBCVP) was synthesized and evaluated as a potential deep UV photoresist. The synthesized polymer has excellent transmittance at 248 nm (absorbance = 0.041 mu m(-1)). In addition, PBCVP possesses good thermal stability up to 200 degrees C and a high glass transition temperature (140-155 degrees C). The thermal deprotection of side-chain ester groups of PBCVP occurs at 200 degrees C, whereas in the presence of acid the cleavage of the t-butyl ester groups of PBCVP begins at about 60 degrees C and completes at about 100 degrees C, followed by evolution of carbon dioxide at similar to 150 degrees C. The deprotected polymer poly(1-vinyl-2-pyrrolidinone-3-carboxylic acid) is soluble in pure water. This resist has a high sensitivity (similar to 1 mJ/cm(2)). (C) 1997 Elsevier Science Ltd.