| US 7,456,933 B2 | ||
| Method for improving the imaging properties of a projection objective for a microlithographic projection exposure apparatus | ||
| Ulrich Wegmann, Koenigsbronn (Germany); Vladimir Kamenov, Essingen (Germany); Thomas Muelders, Erding (Germany); Toralf Gruner, Aalen-Hofen (Germany); and Markus Mengel, Heidenheim (Germany) | ||
| Assigned to Carl Zeiss SMT AG, Oberkochen (Germany) | ||
| Filed on Sep. 08, 2005, as Appl. No. 11/220,643. | ||
| Claims priority of application No. 10 2004 043 280 (DE), filed on Sep. 08, 2004. | ||
| Prior Publication US 2006/0077371 A1, Apr. 13, 2006 | ||
| Int. Cl. G03B 27/54 (2006.01); G03B 27/72 (2006.01) | ||
| U.S. Cl. 355—67 [355/71] | 39 Claims |
| 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.
|