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:
Nov. 03, 1998
Filed:
Sep. 04, 1996
Hideki Hara, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
The semiconductor memory device includes a first conductivity type semiconductor substrate, a tunnel gate oxide film formed on the semiconductor substrate, a floating gate formed on the tunnel gate oxide film, and a control gate formed on the floating gate. The semiconductor substrate includes second conductivity type source and drain regions, a second conductivity type lightly doped region formed so that it covers the source region, and a first conductivity type heavily doped region formed so that it covers at least the drain region and overlaps at least partially with the lightly doped region beneath the floating ate. The semiconductor memory device prevents excessive data erasure regardless of the dispersion in thickness of the tunnel gate oxide film, thereby preventing misreading and enhancing reliability of operation.