| US 7,456,931 B2 | ||
| Device manufacturing method, computer program product and lithographic apparatus | ||
| Laurentius Cornelius De Winter, Vessem (Netherlands); Jozef Maria Finders, Veldhoven (Netherlands); and Maria Johanna Agnes Rubingh, Eindhoven (Netherlands) | ||
| Assigned to ASML Netherlands B.V., Veldhoven (Netherlands) | ||
| Filed on Dec. 10, 2007, as Appl. No. 12/189. | ||
| Application 12/000189 is a continuation of application No. 11/642984, filed on Dec. 21, 2006, granted, now 7,307,690. | ||
| Prior Publication US 2008/0170212 A1, Jul. 17, 2008 | ||
| Int. Cl. G03B 27/42 (2006.01) | ||
| U.S. Cl. 355—53 [378/34; 378/35] | 23 Claims |
| 1. A device manufacturing method comprising projecting an image of a device pattern provided by a patterning device and illuminated
with an illumination arrangement onto a substrate using a projection system having a pupil plane and a plurality of adjustable
elements having respective settings, the method further comprising:
determining an object spectrum for the device pattern;
determining a symmetry of the object spectrum;
constructing a merit function for a wavefront in the pupil plane with the settings of the adjustable elements as variables
with reference to the symmetry;
optimizing the merit function in the area contributing to image formation.
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