Theoretical and experimental optimization of numerical aperture and partial coherence for complementary phase-shift processes

Complementary phase shift processes (c:PSM) have shown great promise for practical implementation of alternating phase shift technology. The incorporation of both binary and phase shift masks into a single resist process requires careful consideration of the illumination conditions. Modeling studies examined the impact of the numerical aperture (NA) and partial coherence (PC) on the depth of focus and exposure latitude of a typical DUV resist process. Experimental verification of the modeling results identified optimal NA/PC conditions for both independent and common mask illumination conditions while demonstrating the utility of lithography simulations for NA/PC optimization in c:PSM processes.