Reduction of thermal non-cyclic error effects in interferometers
First Claim
1. An interferometer assembly for use in a lithography tool used for fabricating integrated circuits on a wafer, wherein the lithography tool includes a support structure and a stage for positioning the wafer relative to the support structure, the interferometer assembly comprising:
- an interferometer configured to direct a measurement beam between the stage and the support structure and combine the measurement beam with another beam to form an output beam which comprises a phase related to a position of the stage relative to the support structure, wherein the interferometer is mechanically secured to the lithography tool through an interferometer surface selected to cause the phase of the output beam to be insensitive to thermal changes of the interferometer over a range of temperatures.
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Abstract
In general, in one aspect, the invention features an interferometer assembly for use in a lithography tool used for fabricating integrated circuits on a wafer, wherein the lithography tool includes a support structure and a stage for positioning the wafer relative to the support structure, the interferometer assembly including an interferometer configured to direct a measurement beam between the stage and the support structure and combine the measurement beam with another beam to form an output beam which includes a phase related to a position of the stage relative to the support structure, wherein the interferometer is mechanically secured to the lithography tool through an interferometer surface selected to cause the phase of the output beam to be insensitive to thermal changes of the interferometer over a range of temperatures.
63 Citations
46 Claims
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1. An interferometer assembly for use in a lithography tool used for fabricating integrated circuits on a wafer, wherein the lithography tool includes a support structure and a stage for positioning the wafer relative to the support structure, the interferometer assembly comprising:
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an interferometer configured to direct a measurement beam between the stage and the support structure and combine the measurement beam with another beam to form an output beam which comprises a phase related to a position of the stage relative to the support structure, wherein the interferometer is mechanically secured to the lithography tool through an interferometer surface selected to cause the phase of the output beam to be insensitive to thermal changes of the interferometer over a range of temperatures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An interferometer assembly for use in a lithography tool used for fabricating integrated circuits on a wafer, wherein the lithography tool includes a support structure and a stage for positioning the wafer relative to the support structure, the interferometer assembly comprising:
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an interferometer configured to direct a measurement beam between the stage and the support structure and combine the measurement beam with another beam to form an output beam which comprises a phase related to a position of the stage relative to the support structure, wherein the interferometer is secured to the lithography tool through an interferometer surface selected to cause a distance between the stage and the support structure along the measurement beam to be insensitive to thermal expansion of the interferometer over a range of temperatures.
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14. An interferometer assembly for use in a lithography tool used for fabricating integrated circuits on a wafer, wherein the lithography tool includes a support structure and a stage for positioning the wafer relative to the support structure, the interferometer assembly comprising:
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an interferometer configured to direct a measurement beam between the stage and the support structure through an exit surface of the interferometer and combine the measurement beam with another beam to form an output beam which comprises a phase related to a position of the stage relative to the support structure, wherein the interferometer is secured to the lithography tool through a portion of the exit surface. - View Dependent Claims (15, 16, 17)
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18. An apparatus, comprising:
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an interferometer, which during operation produces an output beam comprising a phase related to an optical path difference between a path of a first beam, which contacts a measurement object, and a path of a second beam; and
a mechanical fixture for mechanically securing the interferometer to an object, wherein the interferometer is secured to the mechanical fixture at a location of the interferometer that causes the phase of the output beam to be insensitive to thermal changes of the interferometer over a range of temperatures. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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31. An apparatus, comprising:
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an interferometer configured to produce an output beam comprising a phase related to an optical path difference between a path of a first beam which exits a measurement beam surface of the interferometer and contacts a measurement object, and a path of a second beam; and
a mechanical fixture for mechanically securing the interferometer to an object, wherein a portion of the measurement beam surface is secured to the mechanical fixture. - View Dependent Claims (32, 33, 34)
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Specification