Compensation for effects of beam misalignments in interferometer metrology systems
First Claim
1. A method, comprising:
- deriving a first beam and a second beam from an input beam and directing the first and second beams along different paths, where the path of the first beam contacts a measurement object;
producing an output beam comprising a phase related to an optical path difference between the different beam paths;
determining a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam;
monitoring variations in a direction of the input beam; and
using the monitored variations in the direction of the input beam to reduce errors in the determined position associated with deviations of the path of the input beam from a nominal input beam path.
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Abstract
In general, in a first aspect, the invention features methods that include deriving a first beam and a second beam from an input beam and directing the first and second beams along different paths, where the path of the first beam contacts a measurement object, producing an output beam comprising a phase related to an optical path difference between the different beam paths, determining a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam, monitoring variations in a direction of the input beam, and using the monitored variations in the direction of the input beam to reduce errors in the determined position associated with deviations of the path of the input beam from a nominal input beam path.
91 Citations
39 Claims
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1. A method, comprising:
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deriving a first beam and a second beam from an input beam and directing the first and second beams along different paths, where the path of the first beam contacts a measurement object;
producing an output beam comprising a phase related to an optical path difference between the different beam paths;
determining a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam;
monitoring variations in a direction of the input beam; and
using the monitored variations in the direction of the input beam to reduce errors in the determined position associated with deviations of the path of the input beam from a nominal input beam path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 31, 32, 33, 34, 35, 36, 39)
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17. A system, comprising:
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an interferometer configured to derive a first beam and a second beam from an input beam, to direct the first and second beams along different paths, where the path of the first beam contacts a measurement object, and to produce an output beam comprising a phase related to an optical path difference between the different beam paths;
an angle interferometer configured to monitor variations in a direction of the input beam; and
an electronic controller configured to determine a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam and to use the monitored variations in the direction of the input beam to reduce errors in the determined position associated with deviations of the path of the input beam from a nominal input beam path. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 37, 38)
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Specification