Patent ID: 6987555
Filing Date: 2006-01-17
Classification: G03F

Abstract:
1. A method of calibrating level sensors of at least two lithographic projection apparatus to correct machine to machine level sensor process dependency, said method comprising: using a first lithographic apparatus, measuring a first set of leveling data for a reference substrate, using the first lithographic apparatus, measuring a second set of leveling data for a substrate processed according to a first process; using a second lithographic apparatus, measuring a third set of leveling data for a reference substrate; using the second lithographic apparatus, measuring a fourth set of leveling data for a substrate processed according to the first process; and based on the first, second, third and fourth sets of leveling data, calculating a set of level sensor parameters corresponding to machine to machine level sensor differences for the first process, wherein the machine to machine level sensor differences are measured and stored as intrafield values.