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:
Oct. 05, 1999
Filed:
Jul. 14, 1997
Katsuya Oda, Hachioji, JP;
Eiji Ohue, Kokubunji, JP;
Takahiro Onai, Ome, JP;
Katsuyoshi Washio, Tokorozawa, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A self-aligned bipolar transistor which has a small base resistance and small emitter-base and collector-base capacitances and is operable at high speed is disclosed. This bipolar transistor is characterized in that a low concentration collector region made of single crystal Si--Ge is self-alignedly formed between an intrinsic base of single crystal Si--Ge and an intrinsic base, and that an extrinsic base electrode and an intrinsic base are connected only through a doped external base. With this arrangement, an energy barrier is not established at the collector base interface owing to the formation of the low concentration region of single crystal Si--Ge, so that the transit time of the carriers charged from the emitter is shortened. The connection between the intrinsic base and the extrinsic base electrode via the doped external base results in the reduction of the base resistance. In addition, the self-aligned formation of the emitter-base-collector leads to the reduction in capacitance between the emitter and the base and also between the collector and the base. Accordingly, a high-speed bipolar transistor can be realized and thus, circuits using the transistor are operable at high speed.