Stage alignment in lithography tools
First Claim
1. A lithography system, comprising:
- a stage for supporting a wafer;
an illumination system including a radiation source and a lens assembly, wherein the illumination system is configured to direct radiation through a mask to produce spatially patterned radiation, and the lens assembly is configured to image the spatially patterned radiation onto the wafer;
a first interferometry system configured to monitor a location of the stage within the lithography system as the stage moves relative to the illumination system;
a second interferometry system configured to identify an alignment feature on a surface associated with the stage; and
an electronic controller coupled to the interferometry systems, wherein the electronic controller is configured to determine information about a location of the stage when the alignment feature is identified.
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Abstract
In general, in a first aspect, the invention features a lithography system that includes a stage for supporting a wafer, an illumination system including a radiation source and a lens assembly, wherein the illumination system is configured to direct radiation through a mask to produce spatially patterned radiation, and the lens assembly is configured to image the spatially patterned radiation onto the wafer, a first interferometry system configured to monitor a location of the stage within the lithography system as the stage moves relative to the illumination system, a second interferometry system configured to identify an alignment feature on a surface associated with the stage, and an electronic controller coupled to the interferometry systems, wherein the electronic controller is configured to determine information about a location of the stage when the alignment feature is identified.
87 Citations
40 Claims
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1. A lithography system, comprising:
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a stage for supporting a wafer;
an illumination system including a radiation source and a lens assembly, wherein the illumination system is configured to direct radiation through a mask to produce spatially patterned radiation, and the lens assembly is configured to image the spatially patterned radiation onto the wafer;
a first interferometry system configured to monitor a location of the stage within the lithography system as the stage moves relative to the illumination system;
a second interferometry system configured to identify an alignment feature on a surface associated with the stage; and
an electronic controller coupled to the interferometry systems, wherein the electronic controller is configured to determine information about a location of the stage when the alignment feature is identified. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An interferometry system for identifying an alignment feature on a surface associated with a stage within a lithography tool, the interferometry system comprising:
an interferometer configured to direct two beams derived from a common light source along different paths and to combine light from the two beams that is reflected from the alignment feature to form an output beam comprising information about the location of the alignment feature with respect to the two beams. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. An apparatus, comprising:
a wafer stage having an alignment feature on a surface associated with the stage, the alignment feature having a first facet and a second facet opposite the first facet, wherein the first and second facets are non-parallel to a plane of the surface and each facet is configured reflect a beam from an interferometer designed to identify the alignment feature. - View Dependent Claims (34, 35, 36, 37, 38)
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39. A method, comprising:
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directing two beams derived from a common source along different paths to contact a surface associated with a wafer stage; and
combining light from the two beams that is reflected from an alignment feature in the surface to form an output beam comprising information about the location of the alignment feature with respect to the two beams.
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40. A method, comprising:
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monitoring a location of a stage within the lithography system comprising an illumination system as the stage moves relative to an illumination system;
using an interferometry system to identify an alignment feature on a surface associated with the stage; and
determining information about a location of the stage within the lithography system when the alignment feature is identified.
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Specification