Patent ID: 6981241

Claim:
A method of eliminating phase conflict centers in alternating phase masks, wherein a predetermined layout having structures provided for imaging is taken as a basis, the method which comprises the following steps: determining critical structures having a width less than a predetermined width W and being bounded by phase-shifting regions on both sides; determining: overlap regions between straight segments of the critical structures, interaction regions between phase-shifting regions; and end regions of the critical structures, degenerate critical structures formed by subtracting the overlap regions from the critical structures; forming layout groups by combining degenerate critical structures, phase-shifting regions, and interaction regions between phase-shifting regions minus all the end regions; forming outer boundaries around free regions within the layout groups, and thereby determining from each outer boundary a number of paths of contact with the degenerate critical structures and ascertaining a phase conflict center if the number is an odd number; determining combinatorial connection paths either connecting two outer boundaries representing phase conflict centers to one another or connecting an outer boundary representing a phase conflict center to the outer contour of a layout group thereof, wherein only an odd number of combinatorial connection paths proceed from each outer boundary representing a phase conflict center; and modifying degenerate critical structures and interaction regions and also, if appropriate, overlap regions running along the combinatorial connection paths or being in contact therewith, to thereby eliminate the phase conflict centers.