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:
Nov. 21, 1989
Filed:
Jan. 25, 1988
Shigeru Komatsu, Kitakyushu, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
In an NPN transistor, a contact base region, an active base region, and a further base region are formed in the silicon substrate. The further base region is between the contact base region and the active base region, and is adjacent to the contact base region and the active base region. The further base region has a depth shallower than that of the contact base region and deeper than that of the active base region. In the method of forming the bipolar transistor, a polysilicon semiconductor layer is formed on a semiconductor substrate. The polysilicon semiconductor layer is partially etched to form a base leading electrode and an emitter leading electrode. A semiconductor impurity is implanted into a base forming region of the silicon substrate via that portion where the polysilicon semiconductor layer is removed.