Simulation-based EUV source and mask optimization

Source and mask optimization has become a promising technique to push the limits of 193 nm immersion lithography. As the introduction of EUV lithography is at least delayed to the 22 nm technology node, sophisticated resolution enhancement techniques will already be required at a very early stage. Thus, pinpointing ideal mask layouts, mask materials, and illumination settings are as important aspects for EUV as for optical lithography. In this paper, we propose the application of global optimization techniques to identify appropriate process conditions for EUV lithography, using rigorous mask and imaging simulations.