Patent ID: 9715181
Date: 2017-07-25
CPC Classifications: G03F

Claim:
1. A method comprising; (a) supporting a calibration substrate in a lithographic apparatus using a substrate support, the calibration substrate carrying a set of first marks; (b) operating a patterning system to apply a pattern comprising a set of second marks onto the calibration substrate, each second mark overlying a first mark; (c) obtaining an overlay measurement on the basis of the overlying first and second marks; and (d) using the overlay measurement to calculate calibration data to correct an apparatus-specific deviation of the lithographic apparatus, wherein operating the patterning system to apply the pattern comprising the set of second marks is repeated while the substrate remains supported by the substrate support so as to apply different sets of second marks while varying an operating parameter of the lithographic apparatus, other than or in addition to an operating parameter to induce overlay shift, between applying the sets of second marks and including a shift between the different sets of second marks such that an overlay measurement of each set can be distinguished.