Self-limiting multi-level programming states
US6233175A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 2000 |
| Grant date | May 15, 2001 |
| Priority date | — |
| Expiry date | Oct 21, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C11/5635
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method of programming flash EEPROM devices that provides self-limiting multi-level programming states. Each cell in the flash EEPROM device can be programmed to have one of multiple threshold voltages. Each cell to be programmed has a programming voltage applied to the gate, a programming voltage applied to the drain and bias voltage applied to either the source (V.sub.s) or to the substrate (V.sub.sub) or both. The bias voltages V.sub.s or V.sub.sub are determined during a precharacterization procedure and each desired threshold voltage has a corresponding bias voltage V.sub.s or V.sub.sub that provides the desired threshold voltage during the programming procedure. The bias voltages V.sub.s or V.sub.sub are selected to provide self-limiting programming by the effective vertical field E.sub.v =V.sub.g -V.sub.t -(either V.sub.s or V.sub.sub), where V.sub.t increases during programming until the programming stops. The lateral field E.sub.l =V.sub.d -(either V.sub.s and/or V.sub.sub) is adjusted during programming to keep the lateral field E.sub.l equal to V.sub.d.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.