Patent ID: 8908148
Filing Date: 2014-12-09
Classification: G01N,G03F

Abstract:
1. A method comprising: obtaining a plurality of surface level measurements of a substrate at a plurality of different level sensing locations across the substrate; determining a focus setting for an exposure field region in accordance with a plurality of the surface level measurements having level sensing locations corresponding to the exposure field region; exposing the exposure field region on the substrate with a focus offset defined with reference to the focus setting to produce a calibration pattern at a target location; obtaining a focus-dependent property measurement of the calibration pattern measured using an inspection apparatus; and calibrating the inspection apparatus using the focus-dependent property measurement, the focus offset and at least one of the plurality of surface level measurements having a level sensing location corresponding to the target location, the plurality of surface level measurments representing local focus deviations caused by unflatness of the substrate within the exposure field region at the time of exposing the calabiration pattern.