Methods and apparatuses for preparing layouts and masks that use phase
shifting to enable production of subwavelength features on an integrated
circuit in close (optical) proximity to other structures are described.
One embodiment selects from several strategies for resolving conflicts
between phase shifters used to define features and (optically) proximate
structures that are being defined other than by phase shifting. One
embodiment adds additional phase shifters to define the conflicting
structures. Another embodiment optically corrects the shape of the phase
shifters in proximity to a conflicting structure. Resulting integrated
circuits can include a greater number of subwavelength features even in
areas that are in close proximity to structures that were not initially
identified for production using a phase shifting mask.