Surface imaging resists for 193 nm lithography

193 nm radiation causes direct photocrosslinking of polymer films which is sufficient to generate silylation selectivity under appropriate conditions. A variety of phenolic based polymers and blends with photoactive compounds were studied for their suitability as resists in a 193 nm, positive-tone, silylation process. Meta-cresol novolac resists and polyvinylphenol resists show the best sensitivity for this process. The threshold dose required to restrict diffusion of the silylating agent depends strongly on the composition of the resist. Sensitivities range from 12mJ/cm2 to over 100 mJ/cm2 for various novolac and polyvinylphenol materials. Wide variations in sensitivity have been found between different synthetic methods of the same resin, different molecular weight characteristics, and different functional modifications.