Lithographic apparatus and device manufacturing method
A lithographic apparatus includes a movable object and a control system to control the position of the movable object. The control system includes a position measurement system configured to measure the position of the movable object, a comparative unit configured to generate a servo error signal by...
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Format: | Patent |
Sprache: | eng |
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Zusammenfassung: | A lithographic apparatus includes a movable object and a control system to control the position of the movable object. The control system includes a position measurement system configured to measure the position of the movable object, a comparative unit configured to generate a servo error signal by subtracting a position signal representative of an actual position of the movable object from a reference signal, a control unit configured to generate a first control signal based on the servo error signal, a feed-forward unit configured to generate a feed-forward signal based on the reference signal, an addition unit configured to generate a second control signal by adding the first control signal and the feed-forward signal, and an actuator unit configured to actuate the movable object. A gain of the feed-forward unit is dependent on the position of the movable object. |
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