Non-volatile semiconductor memory cell utilizing asymmetrical charge trapping
US5768192A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 23, 1996 |
| Grant date | Jun 16, 1998 |
| Priority date | — |
| Expiry date | Jul 23, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/0475
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A novel apparatus for and method of programming and reading a programmable read only memory (PRON) having a trapping dielectric sandwiched between two silicon dioxide layers is disclosed that greatly reduces the programming time of conventional PROM devices. Examples of the trapping dielectric are silicon oxide-silicon nitride-silicon oxide (ONO) and silicon dioxide with buried polysilicon islands. A nonconducting dielectric layer functions as an electrical charge trapping medium. This charge trapping layer is sandwiched between two layers of silicon dioxide acting as an electrical insulator. A conducting gate layer is placed over the upper silicon dioxide layer. The memory device is programmed in the conventional manner, using hot electron programming, by applying programming voltages to the gate and the drain while the source is grounded. Hot electrons are accelerated sufficiently to be injected into the region of the trapping dielectric layer near the drain. The device, however, is read in the opposite direction from which it was written, meaning voltages are applied to the gate and the source while the drain is grounded. For the same applied gate voltage, reading in the reverse…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.