Wavefront-based pixel inversion algorithm for generation of subresolution assist features

Abstract

The generation of subresolution assist features (SRAFs) using inverse-lithography techniques demands extensive computational resources which limits its deployment in advanced CMOS nodes. In this paper, we propose a wavefront-based pixel inversion algorithm to quickly obtain inverse masks with a high aerial image quality. Further assisted by a flexible pattern simplification technique, we present effective SRAF generation and placement based on the calculated inverse mask. The proposed approach can be easily inserted prior to a conventional mask correction flow for subsequent concurrent optimizations of both drawn patterns and SRAFs. The innovative pixel inversion and pattern simplification techniques allow quality mask corrections as produced by inverse lithography while maintaining the convenience of standardized/validated process flows currently used in the industry. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Fast source optimization involving quadratic line-contour objectives for the resist image

“…where ||⋅|| is the operation of Euclidean norm. I t is the target aerial image which can be elaborately designed according to the geometric shapes of patterns [19,33,34].…”