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:
Nov. 27, 1979
Filed:
Aug. 21, 1978
Joseph E Johnson, Pittsburgh, PA (US);
Edward Dombrowski, Pittsburgh, PA (US);
Westinghouse Electric Corp., Pittsburgh, PA (US);
Abstract
A method for etching semiconductor fusions to change their electrical characteristic, especially to reduce the firing current of thyristor fusions, to a predetermined desired value is disclosed. The etching is accomplished by subjecting fusions comprised of a body of semiconductor material, for example, silicon, including an anode emitter region therein and an anode electrode affixed thereto, an anode base region, a cathode base region and a gate electrode affixed thereto, and a cathode emitter region having a cathode electrode affixed thereto, to a plasma etchant comprising a mixture of CF.sub.4 and a carrier gas such for example, nitrogen, for a predetermined time interval. Following this etching cycle the firing current of the fusions is measured. Any fusions having a firing current in excess of the desired value at the end of the first etching cycle are subjected to another etching cycle to further reduce the firing current. The etching and measurement cycle is repeated for a predetermined number of cycles. Any fusions having a firing current in excess of the desired value after the predetermined number of etch cycles are scraped.