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US 6,842,256 B2Granted
Compensating for effects of variations in gas refractivity in interferometers
AssigneeZygo Corporation
InventorHenry A. Hill
Life of this patent
Estimating the term…
Abstract
Methods and system for compensating for effects of changes and variations of gas refractivity in a measurement and/or reference beam path of an interferometer are disclosed.
Claims40
A method for use during a photolithography exposure cycle, the method comprising:
- interferometrically measuring a position of a movable stage within a chamber housing a photolithography exposure system;
- monitoring a refractivity at a location within the chamber remote from the interferometric measurement;
- and
- correcting the interferometric position measurement of the stage based on the monitored refractivity and a non-trivial function mapping refractivity at the remote location to that near the interferometric measurement during different stages of the photolithography exposure cycle.
1 more element
A method, comprising:
- interferometrically measuring a position of a movable object within a chamber;
- measuring a refractivity at a first location within the chamber;
- and
- correcting the interferometric position measurement of the object based on the refractivity measurement at the first location and a non-trivial function mapping refractivity at the first location to that near the interferometry measurement.
1 more element
A system, comprising:
- a chamber;
- a movable stage housed in the chamber;
- an interferometry system configured to measure a position of the movable stage along a measurement path, the interferometry system comprising a refractometer configured to monitor a refractivity at a first location within the chamber;
- and
- a controller coupled to the interferometry system, wherein during operation the controller corrects the interferometric position measurement based on the monitored refractivity at the first location and a non-trivial function mapping refractivity at the first location to that at the measurement path during different stages of a process cycle of the system.
2 more elements
Dependencies are inferred from the claim text.