Abstract: Method and apparatus for designing the photomask in the course of designing the Levenson-type phase shift mask, capable of automatically arranging the shifter, of not causing a contradictory spot in a circuit designing stage and of automatically forming a final layout achieving maximum integrity. The method includes the steps of: forming symbolic layout data in which a distance between adjacent clear areas is set to an arbitrary value; determining regions having a mutual phase difference 0.degree. or 180.degree. of light transmitting through adjacent patterns corresponding to the clear areas in the symbolic layout data; executing compaction of the symbolic layout in a manner that design rule S1 is adopted to the clear areas neighboring with the phase difference of 180.degree. and design rule S2 is adopted to the clear areas neighboring with the phase difference of 0.degree.; and forming mask layout data such that S1 is less than S2.

Abstract: Method and apparatus for designing the photomask in the course of designing the Levenson-type phase shift mask, capable of automatically arranging the shifter, of not causing a contradictory spot in a circuit designing stage and of automatically forming a final layout achieving maximum integrity. The method includes the steps of: forming symbolic layout data in which a distance between adjacent clear areas is set to an arbitrary value; determining regions having a mutual phase difference 0.degree. or 180.degree. of light transmitting through adjacent patterns corresponding to the clear areas in the symbolic layout data; executing compaction of the symbolic layout in a manner that design rule S1 is adopted to the clear areas neighboring with the phase difference of 180.degree. and design rule S2 is adopted to the clear areas neighboring with the phase difference of 0.degree.; and forming mask layout data such that S1 is less than S2.

Abstract: A method for designing a phase-shifting mask in a manner that a phase shifter of the mask is arranged so that a phase difference between light transmitted through clear areas with the phase shifter and light transmitted through clear areas without the phase shifter is set to 180.degree. or further different combination of phase differences being such as 0.degree., 90.degree. and 270.degree.. The method includes the steps of: defining a threshold value in a manner that the threshold value falls within a range which is possible to resolve using the phase-shifting masks; measuring a distance between neighboring shapes of the clear area; storing adjacent relationship of the neighboring shapes whose distance is less than the threshold; and automatically placing the phase shifter on one of the neighboring shapes of the clear areas in a manner that mutually neighboring clear area have an opposite phase to each other.