Patent ID: 6493866
Filing Date: 2002-12-10
Classification: G03F

Abstract:
A computer-implemented method for assigning phases to a plurality P1 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 P2 of target features which are less transmissive to the light than the shifter polygons, wherein each of said target features has a portion whose width is less than a predetermined value, and the portion has edges adjacent to the shifter polygons, wherein any two shifter polygons adjacent to respective two edges of any one of said portions and separated by the portion are to be assigned different phases. the method comprising the acts of:selecting a set SP1 comprising at least one shifter polygon from said plurality P1; assigning a phase PH1 to the at least one shifter polygon in set SP1; identifying a set TF1 comprising at least one target feature of said plurality P2 such that each target feature in set TF1 has a portion having an edge adjacent to one of the at least one shifter polygons in set SP1; determining a set SP2 comprising at least one shifter polygon in the plurality P1 such that for each shifter polygon L1 in set SP2, at least one of the following conditions C1 and C2 holds: C1. shifter polygon L1 touches at least one target feature in set TF1; C2. shifter polygon L1 is one of a sequence of shifter polygons in the set SP2 such that the first shifter polygon in the sequence satisfies the condition C1 and each subsequent shifter polygon in the sequence touches the preceding shifter polygon in the sequence; and assigning a phase PH2, different from the phase PHI, to each shifter polygon in set SP2.