Multiple-pass interferometry
First Claim
1. An apparatus comprising:
- a multiple-pass interferometer including reflectors to reflect at least two beams along multiple passes through the interferometer, the multiple passes including a first set of passes and a second set of passes, the reflectors having first alignments that are normal to the directions of the paths of the beams that are reflected by the reflectors, the two beams providing information about changes in a first location on one of the reflectors after the first set of passes, the two beams providing information about changes in the first location and changes in a second location on the reflector after the second set of passes, the paths of the beams being sheared during the first set of passes and during the second set of passes if at least one of the reflectors has an alignment other than the first alignment, and optics to redirect the beams after the first set of passes and before the second set of passes so that shear imparted during the second set of passes cancels shear imparted during the first set of passes.
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Accused Products
Abstract
Interferometry system including a multiple-pass interferometer having reflectors to reflect at least two beams along multiple passes through the interferometer. The multiple passes include a first set of passes and a second set of passes. The reflectors have first alignments that are normal to the directions of the paths of the beams that are reflected by the reflectors. The two beams provide information about changes in a first location on one of the reflectors after the first set of passes, and provide information about changes in the first location and changes in a second location on the reflector after the second set of passes. The paths of the beams are sheared during the first set of passes and during the second set of passes if at least one of the reflectors has an alignment other than the first alignment. The interferometry system includes optics to redirect the beams after the first set of passes and before the second set of passes so that shear imparted during the second set of passes cancels shear imparted during the first set of passes.
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Citations
52 Claims
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1. An apparatus comprising:
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a multiple-pass interferometer including reflectors to reflect at least two beams along multiple passes through the interferometer, the multiple passes including a first set of passes and a second set of passes, the reflectors having first alignments that are normal to the directions of the paths of the beams that are reflected by the reflectors, the two beams providing information about changes in a first location on one of the reflectors after the first set of passes, the two beams providing information about changes in the first location and changes in a second location on the reflector after the second set of passes, the paths of the beams being sheared during the first set of passes and during the second set of passes if at least one of the reflectors has an alignment other than the first alignment, and optics to redirect the beams after the first set of passes and before the second set of passes so that shear imparted during the second set of passes cancels shear imparted during the first set of passes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
a stage to support the wafer;
an illumination system to image spatially patterned radiation onto the wafer;
a positioning system to adjust the position of the stage relative to the imaged radiation; and
the apparatus of claim 1 to monitor the position of the stage relative to the imaged radiation.
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29. A lithography system for use in fabricating integrated circuits on a wafer, the system comprising:
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a stage to support the wafer; and
an illumination system including a radiation source, a mask, a positioning system, a lens assembly, and the apparatus of claim 1;
wherein during operation the source directs radiation through the mask to produce spatially patterned radiation, the 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 interferometer measures the position of the mask relative to the wafer.
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30. A lithography system for use in fabricating a lithography mask, the system comprising:
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a source to provide a write beam to pattern the lithography mask, a stage to support the lithography mask, a beam directing assembly to deliver the write beam to the lithography mask, a positioning system to position the stage and beam directing assembly relative to one another, and the apparatus of claim 1 to monitor the position of the stage relative to the beam directing assembly.
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31. A method for fabricating integrated circuits, comprising:
using the lithography system of claim 28 to support a wafer, image spatially patterned radiation onto the wafer, adjust the position of the stage relative to the imaged radiation, and use the interferometer to monitor the position of the stage relative to the imaged radiation.
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32. A method for fabricating integrated circuits, comprising:
using the lithography system of claim 29 to support a wafer, direct radiation from the source through the mask to produce spatially patterned radiation on the wafer, adjust the position of the mask relative to the radiation from the source, image the spatially patterned radiation onto the wafer, and use the interferometer to monitor the position of the mask relative to the wafer.
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33. A method for fabricating lithography masks, comprising:
using the lithography system of claim 30 to support a lithography mask, deliver a write beam to the lithography mask, position the stage and beam directing assembly relative to one another, and use the interferometer to measure the position of the stage relative to the beam directing assembly.
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34. A method comprising:
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directing a first measurement beam along a first set of passes through an interferometer to a first region on a measurement object;
directing a first reference beam along a first set of passes through the interferometer to a reference object;
combining the first measurement and reference beams to produce a first output beam after the first measurement and reference beams complete the first set of passes;
determining a change in position in the first region on the measurement object;
using optics to direct a portion of the first measurement beam to form a second measurement beam;
using the optics to direct a portion of the first reference beam to form a second reference beam;
directing the second measurement beam along a second set of passes through the interferometer to a second region on the measurement object;
directing the second reference beam along a second set of passes through the interferometer to the reference object;
combining the second measurement and reference beams to produce a second output beam after the second measurement and reference beams complete the second set of passes; and
determining a change in position in the second region on the measurement object;
wherein a rotation of the measurement object relative to the directions of the paths of the first and second measurement beams that are incident on the measurement object imparts beam shear to the first measurement beam during the first set of passes and to the second measurement beam during the second set of passes, and wherein the optics are configured to redirect the portion of the first measurement and reference output beams so that shear imparted upon the second measurement beam during the second set of passes cancels shear imparted upon the first measurement beam during the first set of passes. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42)
supporting the wafer on a moveable stage;
imaging spatially patterned radiation onto the wafer;
adjusting the position of the stage relative to the imaged radiation; and
monitoring the position of the stage relative to the imaged radiation using the method of claim 34.
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36. A lithography method for use in the fabrication of integrated circuits comprising:
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directing input radiation through a mask to produce spatially patterned radiation;
positioning the mask relative to the input radiation;
monitoring the position of the mask relative to the input radiation using the method of claim 34; and
imaging the spatially patterned radiation onto a wafer.
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37. A lithography method for fabricating integrated circuits on a wafer, the 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 the wafer to spatially patterned radiation; and
monitoring the position of the first component relative to the second component using the method of claim 34.
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38. A method for fabricating integrated circuits, the method comprising the lithography method of claim 34.
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39. A method for fabricating integrated circuits, the method comprising the lithography method of claim 35.
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40. A method for fabricating integrated circuits, the method comprising the lithography method of claim 36.
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41. A method for fabricating integrated circuits, the method comprising the lithography method of claim 37.
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42. A method for 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
monitoring the position of the substrate relative to the write beam using the method of claim 34.
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43. An apparatus comprising:
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a multi-axis interferometer for measuring changes in position of a measurement object with respect to multiple degrees of freedom, the interferometer is configured to receive an input beam, direct a first-measurement beam derived from the input beam to make first and second passes to the measurement object about a first point on the measurement object, and then combine the first measurement beam with a first reference beam derived from the input beam to produce a first output beam comprising information about changes in distance to the first point on the measurement object, and the interferometer is further configured to direct a second-measurement beam derived from the input beam to make first and second passes to the measurement object about a second point on the measurement object, and then combine the second measurement beam with a second reference beam derived from the input beam to produce a second output beam comprising information about changes in distance to the second point on the measurement object, wherein the interferometer comprises fold optics positioned to reflect a portion of the first output beam an odd number of times in a plane defined by the incidence of the measurement beams on the measurement objects to define a secondary input beam, and wherein the second measurement beam and the second reference beam are derived from the secondary input beam. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52)
a stage for supporting the wafer;
an illumination system for imaging spatially patterned radiation onto the wafer;
a positioning system for adjusting the position of the stage relative to the imaged radiation; and
the apparatus claim 43 for monitoring the position of the wafer relative to the imaged radiation.
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51. 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 positioning system, a lens assembly, and the apparatus of claim 43;
wherein during operation the source directs radiation through the mask to produce spatially patterned radiation, the 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 interferometer monitors the position of the mask relative to the radiation from the source.
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52. 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
the apparatus of claim 43 for monitoring the position of the stage relative to the beam directing assembly.
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Specification