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:
Sep. 01, 1987
Filed:
Mar. 24, 1986
George R Goth, Poughkeepsie, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
An integrated bipolar transistor having a self-aligned polysilicon base contact is formed by depositing a first doped polysilicon layer and a silicon nitride passivating layer on the surface of a semiconductor substrate having an isolated collector region therein. An opening is formed in the first polysilicon and silicon nitride layers over the collector to expose the surface of the semiconductor substrate. The base region is formed through the opening and a conformal silicon nitride coating is then deposited on the wall of the opening and over the surface of the semiconductor substrate within the opening. A second polysilicon layer is formed on the silicon nitride passivating layer. The second polysilicon layer is reactive ion etched, leaving a polysilicon sidewall on the wall of the opening while removing the rest of the second polysilicon layer. The polysilicon sidewall is then oxidized, and an emitter is formed through the opening. The bipolar transistors of the present invention have high density, high speed and improved device to device uniformity because thinning or shorting of the passivating layer on the polysilicon layer is prevented.