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. 01, 2007
Filed:
Mar. 11, 2005
Yoshifumi Tomomatsu, Fukuoka, JP;
Hideki Takahashi, Tokyo, JP;
Chihiro Tadokoro, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Chiyoda-ku, Tokyo, JP;
Abstract
A CSTBT includes a carrier stored layer () formed between a P base region () and a semiconductor substrate () and the carrier stored layer has an impurity concentration higher than that of the semiconductor substrate (). The P base region () in a periphery of a gate electrode () functions as a channel. When it is assumed that an impurity concentration of a first carrier stored layer region () just under the channel is NDand an impurity concentration of a second carrier stored layer region () other than just under the channel is NDin the carrier stored layer (), the relationship of the impurity concentrations is defined by ND<NDThus, a gate capacity and a short-circuit current can be controlled and variation in threshold voltage can be prevented.