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. 12, 1989
Filed:
Sep. 16, 1988
Yoshihisa Okita, Tokyo, JP;
Oki Electric Industry Co., Ltd., Tokyo, JP;
Abstract
In method of fabricating a bipolar transistor on a semiconductor substrate, the emitter pattern is formed using the horizontal etching effect and filling-in effect of the RF-bias sputtering method, so a fine, self-aligned emitter pattern can be created that is disposed entirely in the center of the active base region without the use of photoetching. In addition, the passive base layer and the emitter layer can approach each other to any desired degree as long as they do not touch, so no high-concentration base layer is necessary, the base resistance is reduced, and the passive base region is reduced to a very small size. Furthermore, after the formation of the base region, the only heat treatment step that alters the diffusion layer profile is the formation of the emitter layer, so the use of a thin epitaxial layer to reduce the collector resistance does not result in proximity of the buried collector layer and the passive base layer.