1. A method, comprising: identifying a pattern for a layer to be formed using a photolithographic mask, the pattern including features having a dimension smaller than a first particular feature size, and at least one relatively large feature, the at least one relatively large feature and another feature in the pattern having respective sides separated by a space between said respective sides, said space having a dimension less than a second particular feature size; and laying out phase shift regions for the identified pattern to produce a phase shift mask, the phase shift mask having a first set of phase shift regions to define said features having a dimension smaller than the first particular feature size, and a second set of phase shift regions to assist definition of said respective side of said at least one relatively large feature.