METHOD AND APPARATUS FOR ENHANCING SIGNAL STRENGTH FOR IMPROVED GENERATION AND PLACEMENT OF MODEL-BASED SUB-RESOLUTION ASSIST FEATURES (MB-SRAF)

摘要

Model-Based Sub-Resolution Assist Feature (SRAF) generation process and apparatus are disclosed, in which an SRAF guidance map (SGM) is iteratively optimized to finally output an optimized set of SRAFs as a result of enhanced signal strength obtained by iterations involving SRAF polygons and SGM image. SRAFs generated in a prior round of iteration are incorporated in a mask layout to generate a subsequent set of SRAFs. The iterative process is terminated when a set of SRAF accommodates a desired process window or when a predefined process window criterion is satisfied. Various cost functions, representing various lithographic responses, may be predefined for the optimization process.