Poly(isobornyl methacrylate-co-3-(t-butoxycarbonyl)-1-vinyl-2-caprolactam) for an environmentally stable chemically amplified resist

Abstract

Poly(isobornyl methacrylate-co-3-(t-butoxycarbonyl)-1-vinyl-2-caprolactam) was synthesized and evaluated as a new matrix polymer for a deep UV resist. The polymer has low absorbance at 248 nm (absorbance: 0.014-0.034 mu m(-1)) and good thermal stability up to 250 degrees C. The diffusion lengths of photo-generated acid in the resist films were studied for various fractions of the basic monomer in the copolymers. The results show that the copolymer with a basic monomer can control acid diffusion. 0.25 mu m line/space patterns were obtained for this resist system using a KrF excimer laser stepper. The pattern profile was not deformed and T-top was not observed after 2 h post-exposure delay. The polymer has etch resistance comparable to the novolac resist under CHF3 plasma.