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. 16, 2004
Filed:
Oct. 22, 2002
Shoichi Kawamura, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A memory cell array of a NAND-type flash memory is divided into a first and second cell arrays, and, during a read operation, a first voltage is applied to non-selected word lines of the first cell array, and a second voltage lower than the first voltage is applied, to non-selected word lines of the second cell array. The first cell array has a comparatively large write operation frequency, and therefore readily assumes an over-programmed state as a result of repeated write operations, whereas the second cell array has a comparatively small write operation frequency, and it is therefore difficult for same to assume an over-programmed state. As a result, the first voltage is made high, such that read problems are avoided even if over-programming arises, and the second voltage is made low, such that a read disturb is suppressed and a data change is avoided.