Thermomechanical stability analysis of large masks (6" × 12") for high-NA EUV lithography

Abstract

The reduction in exposure field size has introduced new challenges with the introduction of high-NA EUV scanners. To address these issues, expanding the current 6" × 6" mask format to 6" × 12" is being considered, requiring prior evaluation before adoption. Even small deviations can significantly impact pattern overlay in high-resolution designs using high-NA processes, making the thermal deformation of the mask due to EUV absorption a critical concern. This study analyzes the effects of various conditions, including large masks, on the thermomechanical stability of the mask during exposure through simulations. The results show that as NA increases, the changing scan conditions lead to higher mask temperatures and deformation. However, at high-NA, the 6" × 12" large mask exhibits superior thermomechanical stability compared to the 6” × 6” mask.