Multilayer optimization for high-NA EUV mask3D suppression

Abstract

Today’s EUV masks are optimized for maximum reflectivity at 6o angle of incidence to support imaging on the 0.33NA scanners. The High-NA EUV scanner will have an NA of 0.55 and anamorphic optics to keep the angles on mask level compatible with current masks. However, for selected use-cases increased Mask-3D effects are observed. In this presentation, we will show the root-cause of these enhanced M3D effects for High-NA EUV and the role of the mask multilayer, as well as how to improve it. We will also show some first experimental results of an ion beam deposited RuSi test sample.