Method of controlling multi-state NROM
US6320786A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 5, 2001 |
| Grant date | Nov 20, 2001 |
| Priority date | — |
| Expiry date | Feb 5, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/0466
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method of controlling the multi-state NROM. A program is executed to inject electric charges that are trapped inside a nitride layer of the NROM. The amount of electric charges trapped inside the nitride layer is controlled so that the memory cell can have different threshold voltages. To read from the memory cell, a first variable voltage is applied to the gate electrode. According to the range of a second variable voltage applied to the drain terminal, three different potential levels, from the smallest to the largest, including a first potential level, a second potential level and a third potential level are set. The second input voltage is adjusted to the first potential level. When a high current is sensed, a first storage state is assumed. If little current is detected, the second input voltage is adjusted to the second potential level. When a high current is sensed, a second storage state is assumed. On the other hand, if little current is detected, the second input voltage is adjusted to the third potential level. Similarly, if a high current is sensed, a third storage state is assumed. Conversely, when little current is detected, a fourth storage state is assumed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.