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. 30, 1995
Filed:
Apr. 19, 1994
Francis J Morris, Plano, TX (US);
Jau-Yuann Yang, Richardson, TX (US);
Donald L Plumton, Dallas, TX (US);
Han-Tzong Yuan, Dallas, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A method of fabricating a semiplanar heterojunction bipolar transistor (10) includes forming a subcollector layer (12) and a collector layer (16) onto a substrate layer (14). A collector implant plug (18) is selectively implanted to connect the subcollector layer (12) to the surface of the heterojunction bipolar transistor (10). A second epitaxial growth process causes a base layer (22), an emitter layer (24), and an emitter cap layer (26) to form on the collector layer (16) and the collector implant plug (18). By this process, the base layer (22) is not exposed to subsequent harmful fabrication steps. A base plug region (28) is selectively implanted to connect the base layer (22) to the surface of the heterojunction bipolar transistor (10). A base contact (32) and an emitter contact (30) are selectively formed within the heterojunction region on the base plug region (28) and the emitter cap layer (26), respectively. Lateral parasitic diodes between the base contact (32) and the emitter contact (30) are etched away to isolate the base contact (32) from the emitter contact (30). The emitter cap layer (26), the emitter layer (24), and the base layer (22) are removed from the vicinity of the collector implant plug (18) to allow formation of the collector contact (34).