Patent ID: 9217931
Filing Date: 2015-12-22
Classification: G03F

Abstract:
1. A method, comprising: determining an intensity distribution in an exit pupil of an illumination system of a microlithographic projection exposure apparatus, wherein the exit pupil is assigned to a point on a mask to be illuminated by the illumination system; describing the determined intensity distribution as a perturbation of an ideal intensity distribution, wherein the perturbation is described as a combination of an intensity modulation and a distortion, wherein: the intensity modulation is described by a linear superposition of functions of a first complete function system; and the distortion is described by linear superposition of vector modes of a complete second function system; evaluating the determined intensity distribution based on scalar superposition coefficients of the linear superpositions; and modifying at least one optical element of the an illumination system based on the evaluation of the determined intensity distribution.