Dynamic interferometer controlling direction of input beam
First Claim
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1. An interferometry system, comprising:
- an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam, wherein the measurement object and interferometer are configured to move relative to each other;
a beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer; and
a control circuit coupled to the positioning system which during operation causes the positioning system to reorient the beam steering element in response to a change in the angular orientation of the measurement object relative to the interferometer.
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Abstract
Interferometers can be configured to maintain a measurement beam substantially orthogonal to a plane measurement mirror and to minimize the lateral beam shear between the measurement and reference beam components of the output beam to a detector. These interferometers use a dynamic beam steering element to redirect the input beam in response to changes in the orientation of the measurement plane mirror. These interferometers may be further configured to measure displacement and change in orientation of the plane mirror or configured in a combination of single pass interferometers fed by the input beam for measuring displacement and change in orientation of the plane mirror.
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Citations
36 Claims
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1. An interferometry system, comprising:
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an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam, wherein the measurement object and interferometer are configured to move relative to each other; a beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer; and a control circuit coupled to the positioning system which during operation causes the positioning system to reorient the beam steering element in response to a change in the angular orientation of the measurement object relative to the interferometer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 17, 18, 19, 20, 21, 22, 23, 24)
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9. An interferometry system, comprising:
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an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam; a beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer; and a control circuit coupled to the positioning system which during operation causes the positioning system to reorient the beam steering element based on information derived from the output beam, wherein the control circuit further comprises a differential angle displacement interferometer, which during operation generates an interference signal related to a difference in propagation directions between the measurement beam and the other beam in the output beam. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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25. A method, comprising:
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directing an input beam to contact a beam steering element prior to entering an interferometer; splitting the directed input beam into a measurement beam and at least one other beam; directing the measurement beam to reflect from a measurement object at least once, wherein the measurement object and the interferometer are configured to move relative to each other; overlapping the reflected measurement beam and the at least one other beam to form an output beam which does not contact the beam steering element; and electronically reorienting the beam steering element in response to a change in the angular orientation of the measurement object relative to the interferometer. - View Dependent Claims (26, 27)
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28. An interferometry system, comprising:
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an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object multiple times, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam; a beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer; and a control circuit coupled to the positioning system which during operation causes the positioning system to reorient the beam steering element based on information derived from the output beam.
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29. An interferometry system, comprising:
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an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object comprising a plane mirror, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam; a beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer; and a control circuit coupled to the positioning system which during operation causes the positioning system to reorient the beam steering element to cause the measurement beam to be orthogonal to the plane mirror for a range of orientations of the plane mirror based on information derived from the output beam.
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30. An interferometry system, comprising:
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an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam; a beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer; and a control circuit comprising an angle displacement interferometer configured to generate an interference signal related to a propagation direction of the output beam, the control circuit being coupled to the positioning system and configured to cause the positioning system to reorient the beam steering element based on information derived from the output beam.
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31. A lithography system for use in fabricating integrated circuits on a wafer, the system comprising:
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a stage for supporting the wafer; an illumination system for imaging spatially patterned radiation onto the wafer; a stage positioning system for adjusting the position of the stage relative to the imaged radiation; and an interferometry system comprising an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam, wherein either the interferometer or the measurement object are mounted on the stage; the interferometry system further comprising a beam steering assembly and a control circuit, the beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer, and the control circuit being coupled to the electronic positioning system which during operation causes the electronic positioning system to reorient the beam steering element based on information derived from the output beam, wherein the interferometry system is configured to monitor the position of the wafer relative to the imaged radiation.
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32. A lithography system for use in fabricating integrated circuits on a wafer, the system comprising:
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a stage for supporting the wafer; and an illumination system including a radiation source, a mask, a mask positioning system, a lens assembly, and an interferometry system comprising an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam, wherein either the interferometer or the measurement object are mounted on the stage; the interferometry system further comprising a beam steering assembly and a control circuit, the beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer, and the control circuit being coupled to the electronic positioning system which during operation causes the electronic positioning system to reorient the beam steering element based on information derived from the output beam, wherein during operation the source directs radiation through the mask to produce spatially patterned radiation, the mask positioning system adjusts the position of the mask relative to the radiation from the source, the lens assembly images the spatially patterned radiation onto the wafer, and the interferometry system monitors the position of the mask relative to the radiation from the source.
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33. A lithography system for fabricating integrated circuits, comprising:
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an interferometry system comprising an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam; the interferometry system further comprising a beam steering assembly and a control circuit, the beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer, and the control circuit being coupled to the positioning system which during operation causes the positioning system to reorient the beam steering element based on information derived from the output beam; and first and second components, the first and second components being movable relative to one another, the interferometer being secured to the second component and the measurement object being rigidly secured to the first component, wherein during operation the interferometry system measures the position of the first component relative to the second component.
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34. A beam writing system for use in fabricating a lithography mask, the system comprising:
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a source providing a write beam to pattern a substrate; a stage supporting the substrate; a beam directing assembly for delivering the write beam to the substrate; a positioning system for positioning the stage and beam directing assembly relative one another; and an interferometry system comprising an interferometer which during operation receives an input beam, separates the input beam into a measurement beam and another beam, directs the measurement beam to contact a measurement object, and overlaps the measurement beam after it reflects from the measurement object with the other beam to form an output beam, wherein either the interferometer or the measurement object are mounted on the stage; the interferometry system further comprising a beam steering assembly and a control circuit, the beam steering assembly having a beam steering element positioned to direct the input beam into the interferometer and to not contact the output beam, and an electronic positioning system to selectively orient the beam steering element relative to the interferometer, and the control circuit being coupled to the electronic positioning system which during operation causes the electronic positioning system to reorient the beam steering element based on information derived from the output beam, wherein the interferometry system is configured to monitor the position of the stage relative to the beam directing assembly.
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35. A lithography method, comprising:
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positioning a first component of a lithography system relative to a second component of a lithography system to expose a wafer to spatially patterned radiation, wherein the first component includes a measurement object; and measuring the position of the first component relative to the second component using an interferometry method that comprises; directing an input beam to contact a beam steering element prior to entering an interferometer; splitting the directed input beam into a measurement beam and at least one other beam; directing the measurement beam to reflect from the measurement object at least once; overlapping the reflected measurement beam and the at least one other beam to form an output beam which does not contact the beam steering element; and electronically reorienting the beam steering element based on information derived from the output beam.
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36. A beam writing method for use in fabricating a lithography mask, the method comprising:
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directing a write beam to a substrate to pattern the substrate; positioning the substrate relative to the write beam; and measuring the position of the substrate relative to the write beam using an interferometry method that comprises; directing an input beam to contact a beam steering element prior to entering an interferometer; splitting the directed input beam into a measurement beam and at least one other beam; directing the measurement beam to reflect from a measurement object at least once; overlapping the reflected measurement beam and the at least one other beam to form an output beam which does not contact the beam steering element; and electronically reorienting the beam steering element based on information derived from the output beam, wherein the position of either the interferometer or the measurement object vary with the position of either the write beam or the substrate.
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Specification