Determination of Acid Diffusion in Chemical Amplification Positive Deep-UV Resists

Abstract

The diffusion of photogenerated acid in chemical amplification resist systems was examined by a newly developed method which allowed an estimation of the diffusion range by simple means. The acid mobility was investigated for various process conditions. It was found that prebake and post-exposure-bake conditions have strong influence on the mobility of acid. The diffusion range of acid is much larger than values estimated from the catalytic volume. Large differences in diffusion characteristics were found for two different resist systems. The diffusion of various sulfonic acids decreased strongly with increasing molecule size.