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. 19, 2002
Filed:
Jul. 05, 2001
Yasuaki Hirano, Tenri, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
In an erase method for a nonvolatile semiconductor memory device in which a memory cell array is divided into blocks, an erase pulse application for erasing information, a first verify operation for verifying a threshold voltage shift due to the erase pulse application and a second verify operation for verifying whether excessive erasure has occurred due to the erase pulse application are performed for memory cells connected to one word line in a certain block. When a memory cell excessively erased is found by the second verify operation, a soft program operation for the memory cell is performed after the second verify operation. The erase pulse application, the first verify operation, and the second verify operation are executed word line by word line in the block.