Patent ID: 7147976

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