Patent ID: 7001693

Claim:
A method for forming a photolithographic mask layout with Sub-Resolution Assist Feature (SRAF) elements on a mask to improve a pattern image comprising the steps of: (a) developing a circuit layout comprising a plurality of features of a pattern, (b) providing a table of SRAF rules relating the size and placement of said SRAF elements as a function of spacing of said features of said pattern, (c) applying said SRAF elements to said features according to said SRAF rules, (d) legalizing said SRAF elements, (e) identifying problem edge segments of said features of said pattern based on insufficient SRAF element coverage, (f) applying a selected bias to said problem edge segments to modify said features of said pattern of features locally in areas of SRAF loss, and (g) providing an output of an enhanced mask layout with a locally modified pattern of features.