Patent US 8,291,354

Merging sub-resolution assist features includes receiving a mask pattern that includes the sub-resolution assist features. A first sub-resolution assist feature is selected to merge with a second sub-resolution assist feature. A merge bar width of a merge bar is established. A distance between the first sub-resolution assist feature and the second sub-resolution assist feature is determined. A merging technique is determined in accordance with the distance and the merge bar width. The first sub-resolution assist feature and the second sub-resolution assist feature are merged according to the identified merging technique.