Process for generating a phase level of an alternating aperture phase shifting mask

A process for generating a phase level of an alternating aperture phase shifting mask comprising:

• obtaining a pattern corresponding to a chrome level design of a mask;
• removing from said pattern all polygons having both X and Y dimensions greater than a predetermined value W1 to create a pattern defined as L1;
• creating a rectangle along the edge of each polygon in pattern L1 if said edge is greater than W1, said rectangles having a predetermined width W2, said rectangles forming a pattern defined as L2;
• merging pattern L1 with pattern L2 to form a pattern defined as L3;
• creating a pattern formed by rectangles within pattern L3 beginning at each edge of pattern L1 having a width less than or equal to W1, said rectangles having a width equal to a corresponding edge and a length extending from said edge to an opposite side of pattern L3, said rectangles forming a pattern defined as L4;
• creating a pattern defined as L5 by subtracting overlapping portions of pattern L4 from pattern L2;
• assigning a phase of 0.degree. or 180.degree. to each polygon of pattern L5 with adjacent polygons having opposite phases;
• creating a pattern defined as L6 by removing all polygons having a phase of 0.degree. from pattern L5;
• and
• creating additional patterns defined as L5-LN corresponding to pattern L6 but having enlarged polygons such that said pattern L6 can be formed in a mask using a voting technique with patterns L6-LN.