Mask optimization accounting for more critical and less critical overlap regions

Abstract

Some embodiments provide a method for optimizing a mask layout generated from a design layout of an IC. Based on an initial mask layout for a first layer, the method generates a simulated wafer image including shapes representing components of the first layer, including a first component that overlaps with a second component on a second layer. The method identifies a more critical first region and a less critical second region of a first shape of the first component that both overlap with a second shape of the second component. The more critical first region is more important to ensuring overlap of the first shape with the second shape. To improve overlap between the first and second shapes, the method uses different costs for the more critical first region and the less critical second region to modify the initial mask layout to produce a modified mask layout.