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:
Dec. 08, 1998
Filed:
Aug. 28, 1995
Fumitoshi Yamamoto, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
An n-type epitaxial layer is formed on a main surface of a p-type silicon substrate. An n-type buried diffusion layer is formed extending in both the p-type silicon substrate and the n-type epitaxial layer. An n-type diffusion layer is formed in the surface of the n-type epitaxial layer, which is disposed above the n-type buried diffusion layer. A p-type diffusion layer is formed so as to surround side ends of the n-type diffusion layer. A p-type buried diffusion layer is formed so as to have a bottom face within the n-type buried diffusion layer and have side ends thereof inside side ends of the p-type diffusion layer. A collector region of a vertical pnp bipolar transistor consists of the p-type buried diffusion layer and the p-type diffusion layer. A p-type diffusion layer, which serves as an emitter region of the pnp bipolar transistor, is formed in the surface of the n-type diffusion layer. Thus, a semiconductor device having a vertical pnp bipolar transistor can be obtained which is capable of reducing its manufacturing cost and improving its reliability.