Model-based SRAF insertion through pixel-based mask optimization at 32nm and beyond

SRAF insertion through inverse microlithography methodologies has been explored at length in recent years as one of the most promising approaches to determining the right placements of Model-based SRAF (MBSRAF) for complex two dimensional geometrical configurations for advanced nodes. This work will discuss the latest development of MBSRAF insertion software at Mentor Graphics. The software system operates on the principles of inverse methods of microlithography or pixel inversion. The ability to examine the image of every pixel in the work region as well as the mathematical solution to synthesize the mask shapes as a cost minimization problem make it possible to reliably deal with SRAF insertion for advanced illumination schemes such as quasar, dipole and cross-quad. Pixel inversion involving high transmission attenuated PSM as well as hard PSM will be also discussed. We will also report on the MRC capability to make the pixel inversion mask shapes manufacturable.