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:
Aug. 12, 1997
Filed:
Mar. 18, 1996
Toshiya Sato, Tokyo, JP;
NEC Corporation, , JP;
Abstract
The non-volatile semiconductor memory disclosed includes an X-decoder and word line potential supply circuits, and a current setting/holding circuit. The X-decoder and the word line potential supply circuits set all word lines ground potential in the flash erasing operation, to a predetermined first over-erasing judgment reference potential in an 'on' cell detecting operation, and to a predetermined second over-erasing judgment reference potential for judgment of over-erasing deeper than the first over-erasing judgment reference potential and, in an 'on' cell specifying operation, set predetermined selected word lines to the first over-erasing judgment reference potential while setting other word lines than the selected word line to the second over-erasing judgment reference potential. The current setting/holding circuit sets the reference current in an 'on' cell specifying reference current setting operation such that the result of the check by a sense amplifier is 'on'. It is possible to eliminate the possibility of generation of a memory cell transistor in a non-erased state, thus ensuring quick operation.