Photocopying – Projection printing and copying cameras – Detailed holder for original
Patent
1978-12-11
1981-05-05
Wintercorn, Richard A.
Photocopying
Projection printing and copying cameras
Detailed holder for original
269 21, 308 9, 355 53, 355 54, 356144, G03B 2762, G03B 2764
Patent
active
RE0306010
ABSTRACT:
This describes an apparatus and method especially adapted for positioning a semiconductor wafer in a preferred plane with respect to a photomask so as to achieve improved photolithographic focusing. The apparatus comprises a holder, provided with a surface for receiving a semiconductor wafer thereon, mounted in a chuck which mates with an adaptor ring containing both driver mechanisms and sensors for sensing and positioning the wafer. The sensors define a reference plane and converts the spacing between the reference plane and the front surface of the semiconductor wafer into electrical signals which can be fed to the driver mechanisms to position, with both rotational or translational motion, the plane of the wafer by moving the holder until all the signals from the sensors are nulled. Once the wafer is properly aligned, the sensors continually monitor the position of the wafer and the driver mechanisms continually provide loading to the wafer holder to continually maintain the wafer in its preferred position with respect to the established reference plane.
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patent: 2968994 (1961-01-01), Shurcliff
patent: 3674368 (1972-07-01), Johannsmeier
patent: 3722996 (1973-03-01), Fox
patent: 3858978 (1975-01-01), Johannsmeier
patent: 3876301 (1975-04-01), Kosugi et al.
patent: 3940211 (1976-02-01), Johannsmeier
patent: 3955072 (1976-05-01), Johannsmeier et al.
patent: 4068947 (1978-01-01), Buckley
IBM Technical Disclosure Bulletin, "Semiconductor Leveling System", J. W. Buechele, vol. 16, No. 10, Mar. 1974, pp. 3255-3256.
Horr Andrew F.
White William F.
International Business Machines - Corporation
Thornton Francis J.
Wintercorn Richard A.
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