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

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 copolyme r with a basic monomer can control acid diffusion. 0.25 mu m line/space pat terns were obtained for this resist system using a KrF excimer laser steppe r. 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 no volac resist under CHF3 plasma.