Estimation of electron affinity of photoacid generators: density functional theory calculations using static and dynamic models

Abstract

The electron affinity (EA) of a photoacid generator (PAG) is an important parameter for estimating the acid generation efficiency in a chemically amplified resist upon exposure to ionizing radiation such as EUV light and an electron beam because the electron attachment of PAG induces PAG decomposition and acid generation. In this study, EAs of ionic and non-ionic PAGs were estimated by density functional theory calculations using static and dynamic models. The former model indicated that radical anions are produced without changing the PAG structure even after electron attachment. The latter model indicated that the product structures are relaxed to their stable structures after electron attachment (dissociative electron attachment). By demonstrating the relationship between the EA and acid yield, the most preferable model was revealed.