Patent ID: 8681309
Filing Date: 2014-03-25
Classification: G03F

Abstract:
1. A method of calibrating a model of the effect on an optical characteristic of a projection system of a lithographic system of performing exposures according to a recipe, the method comprising in order: first measuring the optical characteristic of the projection system to generate a first measurement result; exposing a substrate according to the recipe; second measuring the optical characteristic of the projection system to generate a second measurement result; allowing the projection system to cool for a period of time; third measuring the optical characteristic of the projection system to generate a third measurement result; second exposing according to the recipe; and fourth measuring the optical characteristic of the projection system to generate a fourth measurement result, wherein the model has a first part modeling the effect of heating on the optical characteristic and a second part modeling the effect of cooling on the optical characteristic, the first, second, third and fourth measurement results being used to calibrate the first part and the second part, the calibrated first and second parts used for subsequent calculation of a compensatory adjustment of the projection system or other exposure process parameter.