Contribution of mask defectivity in stochastics of EUVL-based wafer printing

Abstract

Two earlier publications showed that mask defectivity contributes to the stochastics of the EUVL-printed image on wafer. The present contribution gives more insights into the methodology and resist models used therein. In addition, an extended study of two types of mask roughness is presented, comprising mask absorber line-edge roughness and rippling of the multilayer mirror on the mask. For both, it is shown that contributions to stochastics are larger than expected purely from normalized intensity log-slope considerations. As a second topic, printability of local defects is readdressed at smaller pitches and more state-of-the-art illumination settings, in preparation to a genuine study of mask defectivity contribution to wafer printing stochastics at high-NA EUV lithography. First results for one-dimensional mask patterns indicate an influence of the anamorphic characteristic of high-NA imaging, showing a different behavior for vertical and horizontal orientations.