In SITU measurement and compensation of errors due to imperfections in interferometer optics in displacement measuring interferometry systems
First Claim
1. A method for determining the location of an alignment mark on a stage using an interferometry system that comprises interferometer optics configured to direct a first measurement beam to reflect from a measurement object, where either the interferometer optics or the first measurement object are attached to the stage, the method comprising:
- measuring a location, x1, of a stage along a first measurement axis using the interferometry system;
measuring a location, x2, of the stage along a second measurement axis;
determining a location of the alignment mark along a third axis based on x1, x2, and a correction term, ψ
3, calculated from predetermined information comprising information characterizing imperfections in the interferometer optics determined using the interferometry system and the stage; and
outputting a signal from an electronic controller based on the determined location of the alignment mark.
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Abstract
In general, in one aspect, the invention features a method for determining the location of an alignment mark on a stage including measuring a location, x1, of a stage along a first measurement axis using an interferometry system, measuring a location, x2, of the stage along a second measurement axis parallel to the first measurement axis, and determining a location of the alignment mark along a third axis parallel to the first measurement axis based on x1, x2, and a correction term, ψ3, calculated from predetermined information including information characterizing imperfections in the interferometry system determined using the interferometry system and the stage.
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Citations
49 Claims
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1. A method for determining the location of an alignment mark on a stage using an interferometry system that comprises interferometer optics configured to direct a first measurement beam to reflect from a measurement object, where either the interferometer optics or the first measurement object are attached to the stage, the method comprising:
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measuring a location, x1, of a stage along a first measurement axis using the interferometry system; measuring a location, x2, of the stage along a second measurement axis; determining a location of the alignment mark along a third axis based on x1, x2, and a correction term, ψ
3, calculated from predetermined information comprising information characterizing imperfections in the interferometer optics determined using the interferometry system and the stage; andoutputting a signal from an electronic controller based on the determined location of the alignment mark. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 39, 40, 41, 42, 43, 44, 47, 48)
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19. A method, comprising:
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monitoring the location of a stage along a first measurement axis using an interferometry system while scanning the stage along one or more paths, wherein the interferometry system comprises interferometer optics configured to direct a measurement beam to reflect from a first measurement object, where either the interferometer optics or the measurement object are attached to the stage; monitoring the location of the stage along a second measurement axis non-parallel to the first measurement axis using the interferometry system while scanning the stage along the one or more paths; and determining information related to imperfections in the interferometer optics based on the monitored locations; and outputting a signal from an electronic controller based on the determined information. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32)
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28. The method of 27, wherein the interferometry system is used to monitor the location of the stage along the first measurement axis.
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33. An interferometry system, comprising:
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interferometer optics configured to direct a measurement beam to reflect from a first measurement object and to provide an output beam comprising information about location, x1, of a stage along a first axis, where the interferometer optics or the first measurement object are attached to a stage; a detector configured to receive the output beam; and an electronic controller coupled to the detector, wherein during operation the electronic controller determines a location of the stage along a third axis based on x1, a location, x2, of the stage along a second axis and a correction term, Φ
3, calculated from predetermined information comprising information characterizing imperfections in the interferometer optics determined using the interferometry system and the stage. - View Dependent Claims (34, 36, 37, 38, 45, 46)
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35. An interferometry system, comprising:
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a first interferometer configured to monitor the location of a stage along a first measurement axis, the first interferometer comprising interferometer optics configured to direct a measurement beam to reflect from a measurement object, where the interferometer optics or the measurement object are attached to the stage; a second interferometer configured to monitor the location of the stage along a second measurement axis non-parallel to the first measurement axis; and an electronic controller coupled to the first and second interferometers and configured to monitor the location of the stage along the first and second measurement axes while the stage is scanned along one or more paths, and to determine information related to imperfections in the interferometer optics based on the monitored locations.
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49. A method for determining the location of an alignment mark on a stage using an interferometry system that comprises interferometer optics configured to direct a measurement beam to reflect from a measurement object, where either the interferometer optics or the measurement object are attached to the stage, the method comprising:
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measuring a location, x1, of a stage along a first measurement axis using the interferometry system; measuring a location, x2, of the stage along a second measurement axis; determining a location of the alignment mark along a third axis based on x1, x2, and a correction term, ψ
3, calculated from predetermined information comprising information characterizing imperfections in the interferometer optics determined using the interferometry system and the stage; andadjusting the position of the stage based on the determined location of the alignment mark.
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Specification