Patent ID: 7818711

Claim:
A method for forming a phase shifting photomask for use in a lithography process for imaging device structures of a same patterning level onto radiation sensitive material in the fabrication of an integrated circuit, the method comprising: providing a design for the integrated circuit, the design including first and second adjacent device structures; providing one or more mask rules defining the minimum spacing between photomask patterns; determining a position of a first photomask pattern having a critical edge for defining a critical dimension of the first device structure and a non-critical edge for defining a non-critical dimension of the first device structure, the non-critical edge being attached to the critical edge so that the positioning of the non-critical edge will affect the length of the critical edge; determining a position of a second photomask pattern having a critical edge for defining a critical dimension of a second device structure and a non-critical edge for defining a non-critical dimension of the second device structure, the non-critical edge being attached to the critical edge so that the position of the non-critical edge will affect the length of the critical edge, the critical edge of the first photomask pattern being generally parallel to the critical edge of the second photomask pattern, and the non-critical edge of the first photomask pattern being adjacent and generally parallel to the non-critical edge of the second photomask pattern; determining a spacing distance of the non-critical edge of the first photomask pattern from the adjacent non-critical edge of the second photomask pattern; if the spacing distance is greater than the defined minimum spacing, repositioning the non-critical edge of at least one of the first or second photomask patterns to reestablish the spacing distance to be substantially the defined minimum spacing; and forming the phase shifting mask photomask with the positions of the first and second photomask patterns after the repositioning.