Normalized Image Log Slope with Secondary Electron Migration Effect in Chemically Amplified Extreme Ultraviolet Resists

In lithography, the normalized image log slope (NILS) is an important metric that describes the quality of an aerial image of incident photons. The chemical gradient is also an important metric that describes the quality of a latent image in terms of line edge roughness. The relationship between NILS and the chemical gradient has been theorized in studies on photolithography. In extreme ultraviolet (EUV) resists, however, secondary electrons contribute to the image formation in contrast to the case of photoresists. In this study, we proposed a NILS in which secondary electron migration is taken into account. (C) 2009 The Japan Society of Applied Physics