Patent ID: 7456933
Filing Date: 2008-11-25
Classification: G03F

Abstract:
1. A method for improving the imaging properties of a projection objective of a microlithographic projection exposure apparatus, comprising: A. providing a mask to be projected; B. determining locations in an exit pupil of the projection objective which are illuminated by projection light during a projection of the mask; C. determining, for at least one image point of the projection objective, an actual value of an imaging quantity at least at the locations determined according to step b), wherein the imaging quantity influences the imaging properties of the projection objective; D. calculating corrective measures such that the actual value of the imaging quantity approximates a desired value of the imaging quantity at the locations determined according to step b), wherein deviations of the actual value from the desired value are taken into account exclusively at the locations determined according to step b); and E. implementing the corrective measures.