Resolution blur of latent acid image and acid generation efficiency of chemically amplified resists for electron beam lithography

Acid generation processes of chemically amplified resists for electron beam (EB) lithography are different from those of chemically amplified photoresists. Although acid generators decompose mainly via their excited state in photoresists, they decompose through electron attachment in EB resists. This difference causes significant blur (degradation of contrast) in latent acid images of EB resists because typical acid generators can react with low-energy electrons (∼0eV). It has been widely accepted that the contrast is strongly correlated to line edge roughness. We examined the magnitude of blur intrinsic to the reaction mechanism of chemically amplified EB resists by a simulation based on the reaction mechanism. The acid generation efficiency per ionization (secondary electron generation) was also theoretically estimated. The resolution blur and efficiency of current organic resist materials are considered to lie within 4.6–10.3nm and 0.39–0.85, respectively.