A method of generating a mask of use in printing a target pattern on a
substrate. The method includes the steps of (a) determining a maximum
width of features to be imaged on the substrate utilizing
phase-structures formed in the mask; (b) identifying all features
contained in the target pattern having a width which is equal to or less
than the maximum width; (c) extracting all features having a width which
is equal to or less than the maximum width from the target pattern; (d)
forming phase-structures in the mask corresponding to all features
identified in step (b); and (e) forming opaque structures in the mask for
all features remaining in target pattern after performing step (c).
