Patent ID: 7312003

Claim:
A photolithographic mask for defining a target pattern in a layer to be formed using the photolithographic mask, the target pattern comprised of a plurality of features, the photolithographic mask comprising: a dark field mask having phase shifting openings, the phase shifting openings defined by a process comprising placing a plurality of shifter shapes proximate to edges of the plurality of features, wherein the plurality of features includes a first feature having a first edge and a second edge, the first edge adjoining the second edge, and wherein the plurality of shifter shapes includes a first shifter shape placed on the first edge and a second shifter shape placed on the second edge, the first shifter shape and the second shifter shape separated by a minimum distance; assigning phase to the plurality of shifter shapes according to phase dependencies and costs to create a plurality of phase shifters; refining the plurality of phase shifters; and producing a computer readable definition of the photolithographic mask.