Impact of EUV mask roughness on lithography performance

摘要

The influence of surface roughness of an EUV mask on wafer image has been thoroughly investigated by lithography simulation with the Monte Carlo method. Based on the power spectral density of the surface roughness of an actual mask, and based on a given random phase distribution, we have reconstructed a number of rough surfaces with various rms roughness values. We quantitatively estimated the impacts of these reconstructed rough surfaces on wafer images. Furthermore, we also investigated the influence of phase defects formed on the rough surfaces. We then did the process margin analysis that showed the specifications of the surface roughness.