Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1992-12-29
1993-09-07
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
356401, G01N 2186
Patent
active
052431959
ABSTRACT:
An exposure apparatus for exposing mask patterns on a sensitive plate comprises a set (for X and Y direction) of a laser interferometer for measuring a position of a wafer stage and satisfying Abbe's condition with respect to a projection lens and a set (for X and Y direction) of the laser interferometer and satisfying Abbe's condition with respect to off-axis alignment system.
When a fiducial mark on the wafer stage is positioned directly under the projection lens, a presetting is performed so that measuring values by the two sets of laser interferometers are equal to each other.
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patent: 5138176 (1992-08-01), Nishi
IBM Technical Disclosure Bulletin, "Aligning Semiconductor Masks," vol. 13, No. 7, Dec. 1970, p. 1816.
Nelms David C.
Nikon Corporation
Shami K.
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