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:
Dec. 08, 2009
Filed:
Jun. 29, 2007
Hea Jong Yang, Seoul, KR;
Hea Jong Yang, Seoul, KR;
Hynix Semiconductor Inc., Icheon-shi, KR;
Abstract
A method for erasing data of a NAND flash memory device including memory cell blocks may include using a first erase voltage applied to memory cells of a block to be erased. A first verification may be performed to verify erased states of the memory cells using a first verify voltage different than a second verify voltage. Memory cells that have not passed the first verification process are classified as a first group and a verification is performed on memory cells that have passed the first verification using the second verify voltage. Memory cells that have passed the second verification are classified as a second group and memory cells that have not passed the second verification are classified as a third group. Then data of the memory cells of the three groups are erased using first, second and third step voltages and first, second and third erase voltages, respectively.