Pupil, mask, wavefront co-optimization for enhanced EUV patterning: reducing LWR and evaluating overlay

Mask 3D (M3D) effects present a significant challenge in extreme ultraviolet (EUV) lithography, impacting both contrast and best focus shifts. Previous work has demonstrated that pupil, mask, wavefront Co-Optimization (PMWO), can effectively mitigate M3D effects, resulting in improved lithography performance. However, concerns have been raised about the potential degradation of overlay performance with PMWO solutions. In this work, we show that PMWO enables improved line-width roughness (LWR), or reduced dose at constant LWR, providing a pathway for enhanced process control. Furthermore, we characterize the overlay impact of employing asymmetric pupils, assessing the trade-offs introduced by this approach. Our results underscore the potential of PMWO to address M3D-induced patterning challenges while maintaining or improving overlay performance in EUV lithography.