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:
Mar. 03, 1998
Filed:
Mar. 10, 1995
Naoto Okabe, Chita-gun, JP;
Naohito Kato, Kariya, JP;
Nippondenso Co., Ltd., Kariya, JP;
Abstract
An insulated gate field effect transistor comprising a semiconductor substrate having one side on which a cell area is composed of a plurality of first wells of a first conductivity type, each of the first wells containing a source region of a second conductivity type. A channel region is defined in the surface portion of the semiconductor substrate adjoining to the source region, and a gate electrode is formed, via a gate insulating film, at least over the channel region. A source electrode is in common contact with the respective source regions of the plurality of first wells. The semiconductor substrate has a drain electrode provided on another side. A current flows between the source electrode and the drain electrode through the channel being controlled by a voltage applied to the gate electrode. A guard ring area is disposed on the one side of the semiconductor substrate so as to surround the cell area. The source electrode has an extension connected to a second well of a second conductivity type formed in the one side between the cell area and the guard ring area to provide a by-pass such that, when a current concentration occurs within the guard ring area, the concentrated current is conducted directly to the source electrode in the cell area through the by-pass, thereby preventing the concentrated current from causing a forward biassing between the first wells and the source region.