Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1984-01-12
1987-01-13
Willis, Davis L.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
250557, G01J 120
Patent
active
046366261
ABSTRACT:
An alignment apparatus for aligning a semiconductor wafer with an optical mask containing a circuit pattern to be exposed onto the wafer in the fabrication of semiconductor devices by a proximity exposure apparatus. The alignment apparatus includes light beam radiating means for radiating a first and second light beams which are imaged at positions separated by a given gap in a direction substantially perpendicular to two flat sheets, first and second detecting means for respectively detecting the imaging condition of the first and second light beams at the flat sheets, means for relatively moving the light beam radiating means and the flat sheets, and means for discriminating the order of generation of signals from the first and second detecting means, whereby the value of each gap between the selected areas of the two flat sheets at a plurality of places is detected with a high degree of accuracy without changing the gap between the flat sheets thereby making it possible to correct the parallelism, inclination, etc., of the flat sheets.
REFERENCES:
patent: 3796497 (1974-03-01), Mathisen et al.
patent: 3990798 (1976-11-01), White
patent: 4243877 (1981-01-01), Cruz
patent: 4315201 (1982-02-01), Suzuki et al.
patent: 4395117 (1983-07-01), Suzuki
patent: 4504144 (1985-03-01), Trost
Hazama Junji
Izawa Hisao
Kato Kinya
Tanimoto Akikazu
Gatto James G.
Meller Michael N.
Nippon Kogaku K.K.
Willis Davis L.
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