Defect-aware reticle floorplanning for EUV masks

Abstract

Fabricating defect-free mask blanks remains a major "show-stopper" for adoption of EUV lithography. One promising approach to alleviate this problem is reticle floorplanning with the goal of minimizing the design impact of buried defects. In this work, we propose a simulated annealing based gridded floorplanner for single project reticles that minimizes the design impact of buried defects. Our results show a substantial improvement in mask yield with this approach. For a 40-defect mask, our approach can improve mask yield from 53% to 94%. If additional design information is available, it can be exploited for more accurate yield computation and further improvement in mask yield, up to 99% for a 40-defect mask. These improvements are achieved with a limited area overhead of 0.03% on the exposure field. Defect-aware floorplanning also reduces sensitivity of mask yield to defect dimensions.