Unified erase method in flash EEPROM
US6172915A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1999 |
| Grant date | Jan 9, 2001 |
| Priority date | — |
| Expiry date | Sep 30, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C8/12
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A unified erase method used in an array of flash EEPROM memory cells arranged in a plurality of sectors for performing either a single-sector, multiple-sector, or all-sector erasing operation with a reduced amount of total erase time and a uniform V.sub.T distribution as good as that of a single-sector erase operation is provided. An erase-verify operation is performed sequentially on the plurality of sectors from a first sector to a last sector beginning with a first address of each sector if its corresponding erase-on signal is not turned OFF. The current address of each sector is stored at a point where the erase-verify operation failed. An erase pulse is applied only to all sectors simultaneously that have not passed the erase-verify operation. The erase-verify operation is then repeated beginning at the current address stored. The erasing operation is terminated when the erase-on signal has been turned OFF in all sectors in the plurality of sectors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.