Stage system, lithographic apparatus including such stage system, and correction method

摘要

A position measurement system to measure a position of a movable stage includes a reference plate; a plurality of sensors arranged such that, depending on a position of the movable stage relative to the reference plate, at least a subset of the plurality of sensors is configured to cooperate with the reference plate to provide for each of the sensors in the subset respective sensor signals representative of a position of the respective sensor relative to the reference plate; and a processor arranged to determine from the sensor signals a stage position, the processing device configured so as to, when the stage is in a position where an over-determined number of sensor signals is provided by at least the subset of the sensors that are in operational cooperation with the reference plate, (a) determine the stage position from a subset of the over-determined number of sensor signals, and (b) correct a sensor signal of one or more of the sensors from a discrepancy between the determined stage position and a remainder of the sensors signals.