Patent ID: 6777139
Filing Date: 2004-08-17
Classification: G03F

Abstract:
A method of calibrating a lithographic projection apparatus, the apparatus comprising:a radiation system constructed and arranged to provide a projection beam of radiation; a support structure constructed and arranged to support a patterning device, the pattern device constructed and arranged to pattern the projection beam according to a desired pattern; a substrate table to hold a substrate; a projection system constructed and arranged to image the patterned beam onto a target portion of the substrate, the method comprising:imaging at least one alignment marker provided in the patterning device onto a radiation-sensitive layer on a substrate held by the substrate table, wherein the at least one alignment marker comprises at least one grating and has a focus sensitive part and a dose sensitive part, the focus sensitive part and the dose sensitive part each having a plurality of dots on a contrasting background, the pluralities of dots being arranged such that variations in focus settings and dose settings in the imaging cause shifts in the apparent position of the at least one grating.