Patent Document ID: 20030159126
Application ID: 10315906
Patent Status: 0

Claim One:
1. A method implemented in a computer for assigning phases to a plurality P 1 of light shifter polygons of a photolithographic mask through which light is to be transmitted to photolithographically pattern an area on a substrate, wherein the mask has a plurality P 2 of dark target features which are less transmissive to the light than the light shifter polygons, the method comprising: adding plurality P 1 to a group of unassigned shifter polygons; adding plurality P 2 to a group of unused target features; initializing a first output layer for shifter polygons of a first phase; initializing a second output layer for shifter polygons of a second phase; initializing a first derived layer for a current set of shifter polygons; initializing a second derived layer for a current set of target features; initializing a third derived layer for a next set of shifter polygons; adding at least one shifter polygon from the group of unassigned shifter polygons to the first derived layer; adding at least one target feature from the group of unused target features to the second derived layer, wherein the at least one target feature touches a shifter polygon in the first derived layer; removing the shifter polygon in the first derived layer from the group of unused shifter polygons; and adding at least one shifter polygon from the group of unused shifter polygons to the third derived layer, wherein the at least one shifter polygon added to the third derived layer touches the at least one target feature in the second derived layer.