Relationship between normalized image log slope and chemical gradient in chemically amplified extreme ultraviolet resists

Abstract

In lithography, normalized image log slope (NILS) is an important metric that describes the quality of an aerial image of incident photons. The aerial image is converted to a latent image through lithographic processes in the resist. The quality of the latent image correlates with line edge roughness (LER). Chemical gradient is also an important metric that describes the quality of a latent image. In this study, we investigated the relationship between NILS and chemical gradient in chemically amplified resists for extreme ultraviolet lithography. In particular, the effect of effective reaction radius for catalytic chain reactions on the relationship between NILS and chemical gradient was clarified. © 2010 The Japan Society of Applied Physics.