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:
Aug. 22, 1989
Filed:
Dec. 21, 1987
Jonathan I Gittleman, Lawrenceville, NJ (US);
Stanley Bozowski, Trenton, NJ (US);
The United States of America as represented by the Secretary of the Army, Washington, DC (US);
Abstract
A device for non-destructive surface photovoltage testing of silicon-on-sapphire (SOS) wafers employs the electrically equivalent of an inserted capacitance in series in a measuring circuit. A pair of thin irridescent coated (TIC) glasses, are positioned on each side of an SOS wafer with an electrical lead attached to each of the conductive coating of tin oxide and indium tin oxide of the TIC glasses. The glass surface (the non-conductive side) of each TIC glass is positioned adjacent to the sapphire layer and silicon layer respectively. An incident light illuminates the sapphire layer and subsequently illuminates the silicon-sapphire interface with a predetermined wave length of light wherein the silicon absorbs all of the light within about 100A of the silicon-sapphire interface. Thus, the incident light is transmitted through the conductive layer of the first TIC glass which is in electrical contact with a detection circuit. The second TIC glass conductive layer is in electrical contact with a calibration signal input which completes the measuring circuit. The measuring circuit with the electrical equivalent of a capacitor in series is able to detect the altered signal resulting from surface photovoltage (SPV) charge due to absorbed incident light which is a measure of the sapphire-silicon interface condition to permit a non-destructive SPV testing of SOS wafers, greatly speeding the pre-selection process of SOS wafers.