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:
May. 14, 1996
Filed:
Nov. 10, 1994
Northern Telecom Limited, Montreal, CA;
Abstract
A method is provided for forming a transistor for a bipolar, CMOS, or bipolar CMOS integrated circuit. The method is applicable to forming a double polysilicon self-aligned bipolar transistor using a single masking step for defining the emitter structure with a narrow emitter-base contact area and a large emitter contact area. The method comprises selectively providing a tapered body of dielectric to mask a region of the substrate on which an emitter is to be formed. A conductive layer is provided around the tapered body to form base contact electrodes. The tapered body is selectively removed from the substrate without damaging the underlying silicon substrate, to leave a tapered opening; localized dielectric isolation is provided in the form of sidewall spacers on the first conductive layer. The tapered opening is filled with a layer of a second conductive material to form a second electrode i.e. an emitter structure. The resulting structure is fully planarized, preferably by chemical mechanical polishing, to form coplanar contact areas to the base and emitter.