EUV source-mask optimization for 7nm node and beyond

In this paper we introduce new source-mask co-optimization (SMO) capabilities for EUV with specific support of the details of imaging with NXE:33×0 scanners. New algorithms have been developed that fully exploit the adjustability of the light distribution inside the NXE:33×0 flexible illuminator, FlexPupil. The fast NXE M3D+ model accurately predicts the reflective 3D mask effects and enables novel pupil symmetries and mask defocus optimization. This mitigates the H-V bias, Bossung tilt, and pattern shift caused by shadowing and non-telecentricity, and reduces the sensitivity to flare. New pupil optimization flows will be shown. The optimized pupils are fully compliant with NXE:33×0 scanner specifications. We will demonstrate enhanced imaging performance of this NXE specific SMO on 7 nm node logic cut masks and show benefits up to 20% improved CD uniformity, and a reduction in the maximum pattern shifts.