| US 7,532,307 B2 | ||
| Focus determination method, device manufacturing method, and mask | ||
| Maurits Van Der Schaar, Veldhoven (Netherlands); Arie Jeffrey Den Boef, Waalre (Netherlands); Mircea Dusa, Campbell, Calif. (US); and Antoine Gaston Marie Kiers, Veldhoven (Netherlands) | ||
| Assigned to ASMl Netherlands B.V., Veldhoven (Netherlands) | ||
| Filed on Jun. 30, 2005, as Appl. No. 11/170,747. | ||
| Prior Publication US 2007/0003840 A1, Jan. 04, 2007 | ||
| Int. Cl. G03B 27/52 (2006.01); G03B 27/42 (2006.01); G03F 9/00 (2006.01); G03C 5/00 (2006.01) | ||
| U.S. Cl. 355—55 [355/53; 430/5; 430/30] | 14 Claims |
| 1. A method for determining an optimum focus setting for a device manufacturing method using a lithographic apparatus arranged
to transfer a pattern from a patterning device onto a substrate, comprising:
printing a plurality of target markers on a substrate using the lithographic apparatus, different ones of the target markers
being printed with different focus settings, wherein the target markers includes pairs of markers that are identical in form,
but rotated by 180° with respect to each other;
using an angle-resolved scatterometer to measure a property of the target markers; and
determining the optimum focus setting based on a measured property of the target markers, including subtracting a measurement
of the measured property of a first target marker of a respective one of the pairs of markers from a measurement of the measured
property of a second target marker of the respective one of the pairs of markers.
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