Nonvolatile semiconductor memory device capable of realizing optimized erasing operation in a memory array
US7095657B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Sep 14, 2005 |
| Grant date | Aug 22, 2006 |
| Priority date | — |
| Expiry date | Sep 14, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2216/18
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A nonvolatile semiconductor memory device capable of realizing optimized erasing operation in a memory array configuration in which a plurality of pages correspond to and are connected to each of a plurality of word lines and higher speed of the erasing operation. In a flash memory, the erasing operation is performed by an erasing method of erasing a plurality of pages arbitrarily selected in a lump. In a two-page erasing mode, page erasure, page pre-erasure verification, page rewriting process, page pre-rewriting verification, and page upper end determining process are performed in order. The method realizes, particularly, (1) suppression of the number of erase verification times to the minimum by performing erase verification only on arbitrary one even-numbered or odd-numbered page in the pages to be erased in consideration of variations in the erasing characteristic, and (2) prevention of erroneous determination of the upper end of erasure since it is unnecessary to set a memory cell to be rewritten every rewrite verification by continuously executing the rewriting process page by page.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.