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:
Jul. 15, 2008
Filed:
Oct. 06, 2004
Tetsuya Yoshida, Gunma, JP;
Tetsuya Okada, Kumagaya, JP;
Hiroaki Saito, Ota, JP;
Shigeyuki Murai, Gunma, JP;
Kikuo Okada, Saitama, JP;
Tetsuya Yoshida, Gunma, JP;
Tetsuya Okada, Kumagaya, JP;
Hiroaki Saito, Ota, JP;
Shigeyuki Murai, Gunma, JP;
Kikuo Okada, Saitama, JP;
Sanyo Electric Co., Ltd., Osaka, JP;
Gifu Sanyo Electronics Co., Ltd., Gifu, JP;
Abstract
In a conventional semiconductor device, there was a problem that, in a guard ring region, a shape of a depletion layer is distorted and stable withstand voltage characteristics cannot be obtained. In a semiconductor device of the present invention, a thermal oxide film in an actual operation region and a thermal oxide film in a guard ring region are formed in the same process. Thereafter, the thermal oxide film is once removed and is formed again. Thus, a film thickness of the thermal oxide film on the upper surface of the guard ring region is set to, for example, about 8000 to 10000 Å. Accordingly, a CVD oxide film including moving ions is formed in a position distant from a surface of an epitaxial layer. Consequently, distortion of a depletion layer, which is influenced by the moving ions, is suppressed and desired withstand voltage characteristics can be maintained.