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:
Jan. 17, 1995
Filed:
Dec. 28, 1992
S M Sadjadi, San Jose, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A calibration wafer for a patterned wafer scanner is constructed from a substrate of semiconductor material, typically silicon, in which a pattern of features has been etched into the periphery of each die by means of photolithographic techniques. Next, a layer or layers of films composed of materials which are typically used during the fabrication of integrated circuits are deposited. Then a substantially uniform distribution of particles of a known material and size distribution is deposited onto the wafer. A second embodiment of the calibration wafer is one in which a layer or layers of film are first deposited onto a substrate. Then a pattern of features is etched into the periphery of the film covering each die by means of photolithographic techniques. After this step, a substantially uniform distribution of particles is deposited. A method of using such a calibration wafer to calibrate a patterned wafer scanner is also disclosed.