Method for position determination, method for overlay optimization, and lithographic projection apparatus
First Claim
Patent Images
1. A method of position determination, said method comprising:
- obtaining a first set of signals, each signal of the first set corresponding to a respective one of a plurality of portions of light received by a detector, wherein the first set is generated by detection of a first beam of light affected by an alignment feature of a substrate;
obtaining one or more additional sets of signals such that each signal in the one or more additional sets corresponds to a respective one of the plurality of portions and each set is generated by detection of a respective one or more additional beams of light affected by the alignment feature of the substrate;
for each portion of light, determining a variance between a corresponding one of the signals in the first set and a corresponding one or more of the signals in the one or more additional sets;
selecting at least one from among the plurality of portions based on a result of said determining a variance; and
supplying or making available signals corresponding to the at least one from among the plurality of portions which was selected, for further analysis and processing to determine a position.
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Abstract
A method for optimizing an alignment condition of a lithographic projection apparatus. This method comprises projecting a beam of radiation on a target portion of a substrate and measuring a plurality of diffracted signals emitted by the target portion. This method further comprises calculating a variance for each of the plurality of diffracted signals, such that a plurality of variances of the diffracted signals is determined, and adjusting the alignment condition of the lithographic projection apparatus based on analysis of the plurality of variances.
13 Citations
31 Claims
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1. A method of position determination, said method comprising:
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obtaining a first set of signals, each signal of the first set corresponding to a respective one of a plurality of portions of light received by a detector, wherein the first set is generated by detection of a first beam of light affected by an alignment feature of a substrate; obtaining one or more additional sets of signals such that each signal in the one or more additional sets corresponds to a respective one of the plurality of portions and each set is generated by detection of a respective one or more additional beams of light affected by the alignment feature of the substrate; for each portion of light, determining a variance between a corresponding one of the signals in the first set and a corresponding one or more of the signals in the one or more additional sets; selecting at least one from among the plurality of portions based on a result of said determining a variance; and supplying or making available signals corresponding to the at least one from among the plurality of portions which was selected, for further analysis and processing to determine a position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A lithographic projection apparatus comprising:
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an alignment system configured to project an alignment beam onto an alignment feature of a substrate; a detection system configured to generate a first set of signals based on detection of a first beam of light affected by the alignment feature, wherein each signal of the first set corresponds to a respective one of a plurality of portions of light from the first beam, said detection system being configured to generate one or more additional sets of signals based on detection of one or more additional beams of light affected by the alignment feature, each of the one or more additional beams corresponding to a respective one of the additional sets, wherein each signal in the one or more additional sets corresponds to a respective one of the plurality of portions; and a processor configured to calculate, for each portion of light, a variance between a corresponding one of the signals in the first set and a corresponding one or more of the signals in the one or more additional sets and configured to select at least one from among the plurality of portions based on the calculated variances. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A computer-readable data storage medium including instructions describing a method of position determination, said method comprising:
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obtaining a first set of signals, each signal of the first set corresponding to a respective one of a plurality of portions of light received by a detector, wherein the first set is generated by detection of a first beam of light affected by an alignment feature of a substrate; obtaining one or more additional sets of signals such that each signal in the one or more additional sets corresponds to a respective one of the plurality of portions and each set is generated by detection of a respective one or more additional beams of light affected by the alignment feature of the substrate; for each portion of light, determining a variance between a corresponding one of the signals in the first set and a corresponding one or more of the signals in the one or more additional sets; selecting at least one from among the plurality of portions based on a result of said determining a variance; and supplying or making available signals corresponding to the at least one from among the plurality of portions which was selected, for further analysis and processing to determine a position. - View Dependent Claims (26, 27, 28, 29, 30)
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31. A processor configured and arranged to perform a method of position determination, said method comprising:
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obtaining a first set of signals, each signal of the first set corresponding to a respective one of a plurality of portions of light received by a detector, wherein the first set is generated by detection of a first beam of light affected by an alignment feature of a substrate; obtaining one or more additional sets of signals such that each signal in the one or more additional sets corresponds to a respective one of the plurality of portions and each set is generated by detection of a respective one or more additional beams of light affected by the alignment feature of the substrate; for each portion of light, determining a variance between a corresponding one of the signals in the first set and a corresponding one or more of the signals in the one or more additional sets; selecting at least one from among the plurality of portions based on a result of said determining a variance; and supplying or making available signals corresponding to the at least one from among the plurality of portions which was selected, for further analysis and processing to determine a position.
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Specification