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. 22, 2011
Filed:
Jul. 10, 2008
Yasushi Niimura, Nagano, JP;
Takashi Kobayashi, Matsumoto, JP;
Masanori Inoue, Nagano, JP;
Yasuhiko Onishi, Nagano, JP;
Yasushi Niimura, Nagano, JP;
Takashi Kobayashi, Matsumoto, JP;
Masanori Inoue, Nagano, JP;
Yasuhiko Onishi, Nagano, JP;
Abstract
A semiconductor device has an active portion having at least one well region in a semiconductor layer, and a breakdown voltage maintaining structure surrounding the active portion. The maintaining structure includes a conductor layer over each of a plurality of guard rings with an insulating film interposed in between and connected to the respective guard ring. An inner side end portion of each conductor layer projects over the immediate adjacent inner side guard ring. The impurity concentration of the guard rings is set between the impurity concentrations of the semiconductor layer and the well regions. A field plate can extend over the innermost conductor layer with the insulating film interposed in between. The field plate is in contact with the outermost well region and is in contact with the first conductor layer. The outer side end of the field plate extends outwardly beyond an outer side end of the innermost conductor layer. With these arrangements, the guard rings can be shortened and the chip size can be reduced. Furthermore, the device can be made less susceptible to external charge.