Flash memory with pre-detection for data loss
US6819589B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | May 15, 2003 |
| Grant date | Nov 16, 2004 |
| Priority date | — |
| Expiry date | May 15, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/3418
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A new method to detect and to correct a weakly programmed cell in a nonvolatile memory device is achieved. The method comprises providing a plurality of nonvolatile memory cells. A means to read a selected cell compares the performance of the selected cell with the performance of a reference cell. A read state of the selected cell is high if the selected cell exceeds the reference cell. The read state of the selected cell is low if the selected cell exceeds the reference cell. A first read state is obtained by reading the selected cell with the reference cell biased to a first value. A second read state is obtained by reading the selected cell with the reference cell biased to a second value that is greater than the first value. The selected cell is flagged as weakly programmed, high if the first and second read states do not match. A third read state is obtained by reading the selected cell with the reference cell biased to a third value that is less than the first value. The selected cell is flagged as weakly programmed, low if the first and third read states do not match. The selected cell is refreshed if the selected cell is weakly programmed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.