Compensation methods for buried defects in extreme ultraviolet lithography masks

Abstract

Two methods will be presented to compensate for buried defects in patterned extreme ultraviolet (EUV) masks. The goal of the methods in this work is to prescribe modifications to the absorber pattern on an EUV mask with a buried defect so that the final image printed on the wafer matches the intended pattern through focus. The first method uses precalculated design curves to determine the required absorber modification for a given defect. This method is able to compensate for a defect in focus, but not through focus. A second method is presented, covering the defect with absorber that reduces the effect of the defect through focus. Both of these methods are studied with simulation in this work and are equally applicable to pit and bump defects.