Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1991-05-28
1992-09-29
Evans, F. L.
Optics: measuring and testing
By polarized light examination
With light attenuation
250548, 356400, 356401, 356358, 356363, G01B 1100
Patent
active
051517493
ABSTRACT:
A method and apparatus for measuring the coordinate position of a stage on which a semiconductor wafer or the like is placed. Two .theta. interferometers are provided as measuring means for detecting local curving deviations of reflecting surfaces of two plane mirrors perpendicular to each other which mirrors are provided on the stage for detection of the coordinate position of the stage based on the use of light wave interferometers. The curving deviations of the reflecting surfaces of the plane mirrors are measured with the .theta. interferometers to calculate the difference thereby measured and, hence, the true curving deviations of the reflecting surfaces while cancelling out errors in linear movement of the stage. The position of the stage measured with the coordinate position measuring light wave interferometers is corrected by values corresponding to the true curving deviations.
REFERENCES:
patent: 3692413 (1972-09-01), Marcy et al.
patent: 3791739 (1974-02-01), Kawasaki
patent: 4385838 (1983-05-01), Nakazawa et al.
patent: 4676649 (1987-06-01), Phillips
patent: 4958082 (1990-09-01), Makinouchi et al.
Kamiya Saburo
Tanimoto Akikazu
Evans F. L.
Nikon Corporation
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