Compensating for effects of topography variation by using a variable intensity-threshold

Abstract

One embodiment of the present invention provides a system that accurately determines a critical dimension of a feature in a layout by compensating for the effects of topography variation on the performance of an optical lithography process. During operation, the system first receives a layout. Next, the system computes and aerial-image intensity at an evaluation point in the layout using and optical lithography model that models the optical lithography process. Note that the aerial-image intensity is typically compared with a constant intensity threshold to determine a critical dimension of a feature in the layout. The system then computes an intensity threshold based on features in the proximity of the evaluation point, which compensates for the effects of topography variations on the performance of the optical lithography process. Next, the system determines the critical dimension of the feature by comparing the aerial-image intensity with the computed intensity threshold, instead of comparing the aerial-image intensity with the constant intensity threshold.