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:
Feb. 03, 2004
Filed:
Nov. 20, 2002
Alexander Kalnitsky, Portland, OR (US);
Michael Rowlandson, Portland, OR (US);
Fanling H. Yang, Beaverton, OR (US);
Sang Park, Portland, OR (US);
Robert F. Scheer, Portland, OR (US);
Maxim Integrated Products, Inc., Sunnyvale, CA (US);
Abstract
A self-aligned bipolar transistor and a method of formation thereof are provided. The bipolar transistor has an emitter region characterized by a y-shaped structure formed from bilayer polysilicon. The bilayer polysilicon includes a first polysilicon emitter structure and a second polysilicon emitter structure. The method of forming the bipolar transistor includes forming an emitter stack on a substrate. The emitter stack comprises the first polysilicon emitter structure and a plug structure. The emitter stack defines the substrate into a masked portion and exposed adjacent portions. The exposed adjacent portions are selectively doped with a dopant to define an extrinsic base region, wherein the dopant is blocked from entering the masked portion. After selectively doping the extrinsic base region, the plug structure is removed from the emitter stack and the second polysilicon emitter structure is formed on the first polysilicon emitter structure to define the emitter region of the bipolar transistor.