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. 09, 1993
Filed:
Oct. 23, 1990
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A semiconductor device of the present invention is disclosed which includes a semiconductor device of a predetermined conductivity type having a predetermined impurity concentration, a source/drain area formed on the upper surface portion of the semiconductor substrate and a guard ring formed around the source/drain area and having the same conductivity as that of the semiconductor substrate. A gate oxide film is formed on the source/drain area and guard ring and an interconnection layer, such as polysilicon, is formed on the gate oxide film. The guard ring has its impurity concentration set to be higher than that of the semiconductor substrate. The guard ring per se has a portion intersecting with the interconnection layer through a thicker portion of a gate oxide film disposed over the intersecting portion of the guard ring, and a remaining portion, the intersecting portion of the guard ring being higher in impurity concentration than the remaining portion of the guard ring. The gate oxide film is so formed as to be thicker over the intersecting portion of the guard than over the source/drain area in terms of their thickness.