Effect of Molecular Structure on Depth Profile of Acid Generator Distribution in Chemically Amplified Resist Films

The acid generator distribution in resist films is an important issue for fine patterning based on chemical amplification. In particular, extreme ultraviolet (EUV) resists require a high acid generator concentration compared with conventional chemically amplified photoresists. In this study, the depth density profiles in partially protected poly(4-hydroxystyrene) films containing dispersed triphenylsulfonium salts were investigated by X-ray reflectivity measurements to clarify the depth profile of acid generator distribution. It was found that the depth profile depends on the molecular structure of acid generators. The hydrogen bonding between polymers and acid generators affected the depth profile of acid generator distribution.