193-nm photoresists based on norbornene copolymers with derivatives of bile acid

Abstract

We synthesized new chemically amplified photoresists for 193-nm lithography. Norbornene substituted with a derivative of bile acid was copolymerized with maleic anhydride by free radical polymerization. The resulting copolymers have good transmittance at 193 nm and possess excellent thermal stability up to 260 degrees C. With the standard developer, the resists formulated with the copolymers form 0.15-0.18 mu m patterns at doses of 6-7 mJ cm(-2) using an ArF excimer laser stepper.