Effects of polymer interference during acid generation on latent image quality of extreme ultraviolet resists

Abstract

The fluorination of polymers is a promising strategy for enhancing acid production in chemically amplified resists used for extreme ultraviolet (EUV) lithography. However, halogenated polymers are known to react with thermalized electrons and interfere with acid generation. In this study, the effects of the polymer interaction with thermalized electrons on the latent image quality were investigated using a simulation based on the sensitization mechanisms of EUV radiation. The decrease in acid yield by the polymer interference during acid generation leads to an increase in line edge roughness (LER). An increase in the acid generator concentration is effective for suppressing the interference effect. At 20wt% acid generator concentration, the reactivity of the polymer must be less than 2% of that of triphenylsulfonium triflate (a typical acid generator) to suppress the increase in LER to below 10%. © 2008 The Japan Society of Applied Physics.