Process for generating a phase level of an alternating aperture phase

Abstract

A process for generating the phase level pattern of an alternating aperture phase shifting mask is provided. All polygons having both X and Y dimensions greater than a predetermined value are removed from the chrome level design of a mask to create a pattern L1. A rectangle is then created along the edge of each polygon in pattern L1 if the edge is greater than the predetermined value. These rectangles, which form a pattern L2, are then merged with pattern L1 to form pattern L3. A pattern, L4, is created within pattern L3 beginning at each edge of pattern L1 having a width less than or equal to the predetermined width. These rectangles extend from the corresponding edge to the opposite side of pattern L3. Pattern L5 is created by subtracting overlapping portions of pattern L4 from pattern L2. Each polygon of pattern L5 is assigned a phase of 0.degree. or 180.degree. with adjacent polygons having opposite phases. Pattern L6 is created by removing all polygons having a phase of 0.degree. from pattern L5. Pattern L6 corresponds to the phase shifting level.