The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 28, 1977
Filed:
Apr. 12, 1976
Bela Julesz, Warren, NJ (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
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.