Alignment pattern detecting apparatus

Details Alignment pattern detecting apparatus Alignment pattern detecting apparatus

1977-11-30

1978-09-19

Boudreau, Leo H.

Communications: electrical

Digital comparator systems

250201, 3401463Q, 364559, G01J 120

Patent

active

041157621

ABSTRACT:
An alignment pattern detecting apparatus comprises an image pick-up device for scanning and picking up an optical image of alignment pattern formed on a wafer to produce a time-base video signal, and means for sampling at predetermined intervals and converting from analog to digital form the video signal produced by the image pick-up device so that the video signal is returned symmetrically at a predetermined point to determine the degree of matching between the two signals thereby to obtain a point where the degree of matching is the best. This best matching degree point is detected as the center position of the alignment pattern.

REFERENCES:
patent: 3603728 (1971-09-01), Arimura
patent: 3617751 (1971-11-01), Levy et al.
patent: 3852573 (1974-12-01), Dolch
patent: 3955072 (1976-05-01), Johannsmeier
Bradsell et al., "Development of the Photoelectric Microscope," Instrument Practice, Nov., 1965. pp. 1011-1018.

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