Simulation of coherent multiple imaging by means of pupil-plane filtering in optical microlithography

A resolution enhancement technique for optical microlithography based on coherent multiple imaging was investigated with use of Prolith/2 (a commercial lithographic simulation tool). It was shown that a Fabry–Perot etalon placed between the mask and the projection lens of an optical stepper could be interpreted as an appropriate transmission-phase pupil-plane filter. While previous calculations were able to evaluate simple patterns (such as an on-axis contact hole), this new approach also allows the simulation of complex mask patterns. Evaluation of the point-spread function of the optical systems by means of coherent multiple imaging showed that an optimized filter is capable of increasing the resolution by 28% and the depth of focus by 150%. © 1999 Optical Society of America [S0740-3232(99)00408-1] OCIS codes: 110.4190, 070.6110, 110.4850, 100.2980, 110.5220, 050.2230.