Synthesis of norbornene copolymers with acid labile organosilicon protecting groups and their application as dry-developable photoresists for ArF lithography

Abstract

Poly (2-(2-trimethylsilyl-2-propyl)carbonyloxyl-5-norborene-co-maleic anhydride) was synthesized and evaluated as a potential dry developable chemically amplified photoresist. The thermal stability of 2-trimethylsilyl-2-propyl ester was very similar to t-butyl ester, and acid catalyzed cleavage of the 2-propenyltrimethylsilane begins at 80℃. The deprotection of 2-propenyltrimethylsilane group of the polymer takes place in the exposed region after post-exposure bake. The difference of silicon content between the unexposed region and exposed regions is large enough to form patterns using oxygen reactive-ion etching. Poly(2-(2-trimethyl-silyl-2-propyl)carbonyloxy-5-norborene-co-maleic anhydri -de) was valuated as a resist for an ArF excimer laser lithography. 0.18 ㎛ line/space pattern profiles were obtained using the conventional developer (2.38 wt% TMAH solution) with an ArF excimer laser stepper.