Optics: measuring and testing – Inspection of flaws or impurities – Having predetermined light transmission regions
Patent
1976-04-12
1977-06-28
Corbin, John K.
Optics: measuring and testing
Inspection of flaws or impurities
Having predetermined light transmission regions
350 94, 350130, 350320, 351 3, 351 33, 356244, G02B 2722
Patent
active
040322378
ABSTRACT:
An aid-to-operator technique is described for the inspection of periodic structures such as LSI wafers or masks. A commercially available stereomicroscope in conjunction with a depth marker enables the operator to achieve the stereoscopic "wallpaper effect" with the periodic patterns on the structure. Depth markers are strong stimuli, such as random dot stereograms, which influence the operator's visual system to fuse periodic structures adjacent to them. The wallpaper effect is observed when a periodic pattern in the left field of view is fused with a horizontally shifted pattern in the right. Then it is possible to perceive depth at several depth planes. One of these corresponds to the fusion of patterns in the left eye's view with horizontally adjacent patterns in the right eye's view. If one or more such patterns (chips) on a wafer are defective, the deviation between the two fields of view will appear to flicker in and out of the plane of the fused image. Defects are observed as deviations between fused structures and the flicker attracts the operator's attention to the location of the defects. Sample holders are also described for the simultaneous presentation of the depth marker and the structure.
REFERENCES:
patent: 2674156 (1954-04-01), Mahler
Julesz, Foundations of Cyclopean Perception, University of Chicago Press, pp. 89-91, 186-201, 249, 285-288, 315, 1971.
Julesz, "Cooperative Phenomena in Binocular Depth Perception", American Scientist, vol. 62, No. 1, pp. 32-43, 1974.
Julesz, "Binocular Depth Perception of Computer Generated Patterns", Bell System Tech. J., vol. 39, pp. 1125-1162, 1960.
Julesz, "Texture and Visual Perception", Scientific American, vol. 212, No. 2, pp. 38-48, 1965.
Bell Telephone Laboratories Incorporated
Corbin John K.
Koren Matthew W.
Urbano Michael J.
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