Optics: measuring and testing – By configuration comparison – With comparison to master – desired shape – or reference voltage
Patent
1977-05-12
1979-02-20
Corbin, John K.
Optics: measuring and testing
By configuration comparison
With comparison to master, desired shape, or reference voltage
250561, 356354, 356448, G01B 1130, G01N 2148
Patent
active
041403975
ABSTRACT:
A collimated beam of light is directed onto a face of a microcircuit chip. If the configuration side of the chip is up and if the chip has a typical pattern predominantly comprised of two orthogonal sets of lines, the light reflected from the chip will be formed in a cross shaped diffraction pattern with most of the light concentrated in the center of the cross. If, however, the chip is upside down so that a plain face is exposed to the light, the light will be reflected fairly uniformly from the chip. By measuring the reflected light in a small center zone as well as in a larger zone and the light measurements are compared, it can be determined whether the diffraction pattern is present thereby revealing whether the chip is right side up, i.e. configuration side up.
REFERENCES:
patent: 3229564 (1966-01-01), Meltzer
patent: 3597045 (1971-08-01), Mathisen
patent: 3957376 (1976-05-01), Charsky et al.
Ikeda et al., "Ceramic Surface Inspection Using Laser Technique" Japanese Jr. of App. Physics vol. 14, Suppl. 14-1 pp. 487-192, 1975.
Lendaris et al., "Diffraction-Pattern Sampling for Automatic Pattern Recognition", Proc. IEEE vol. 58 #2, 2-1970, pp. 198-216.
Corbin John K.
General Motors Corporation
Hill Warren D.
Punter Wm. H.
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