Patent ID: 8134683
Filing Date: 2012-03-13
Classification: G03F

Abstract:
1. A device manufacturing method using a lithographic apparatus comprising: an illuminator configured to illuminate a patterning device with a radiation beam having an illumination arrangement, and a projection system configured to project radiation in a modulated beam to form an image of the pattern onto a substrate, the projection system having a pupil plane and an adjustable element configured to adjust an aberration of the projection system in response to a control setting, the method comprising: receiving information regarding the pattern and the illumination arrangement; determining a region of interest based on the information regarding the pattern and the illumination arrangement using a non-transitory computer system comprising a computer program to execute the determining, the region of interest being a non-circular region of the pupil plane through which substantially all of the radiation of the modulated beam that contributes to formation of the image passes; obtaining a set of basis functions that are orthogonal over the region of interest; expressing the wavefront in the pupil plane in terms of the basis functions that are orthogonal over the region of interest and a set of coefficients; and determining a value of the control setting to minimize the values of the coefficients.