Computational lithography solutions to support EUV high-NA patterning

The EUV High-NA scanner brings innovative design changes to projection optics, such as introducing center obscuration and the anamorphic projection optical system in the projection optics box (POB) to improve the system transmission while the NA is improved1 . These design changes need to be accounted for in the computational lithography software solutions, to ensure accurate modeling and optimization of the High-NA system performance on wafer. In this paper, we will systematically investigate the benefits of Source Mask Optimization (SMO) and mask only optimization to explore EUV High-NA full chip patterning solutions, where mask 3D effects (M3D) are captured in the optical modeling. The paper will focus on assessing the performance (including process window, depth of focus, normalized image log slope) of through-pitch 1D Line/space (L/S) patterns and 2D Contact/Hole (CH) patterns after aforementioned optimizations and demonstrate the impact of center obscuration on imaging. In addition, we will investigate the effect of sub-resolution assistant feature (SRAF) on High-NA patterning via comparing the optimized lithographic performance with and without SRAF. These findings will help determine the most optimal patterning solutions for EUV High-NA as we move towards the first High NA EUV insertion. The paper will also discuss the anamorphic SMO where MRC and mask description needs to change from wafer plane (1x1) to scaled reticle plane (1x2). The interfield stitching will also be briefly discussed in this paper.