Two bit non-volatile electrically erasable and programmable semiconductor memory cell utilizing asymmetrical charge trapping
US6768165B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 1, 1997 |
| Grant date | Jul 27, 2004 |
| Priority date | — |
| Expiry date | Aug 1, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D64/037
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A non-volatile electrically erasable programmable read only memory (EEPROM) capable of storing two bit of information having a nonconducting charge trapping dielectric, such as silicon nitride, sandwiched between two silicon dioxide layers acting as electrical insulators is disclosed. The invention includes a method of programming, reading and erasing the two bit EEPROM device. The nonconducting dielectric layer functions as an electrical charge trapping medium. A conducting gate layer is placed over the upper silicon dioxide layer. A left and a right bit are stored in physically different areas of the charge trapping layer, near left and right regions of the memory cell, respectively. Each bit of the memory device is programmed in the conventional manner, using hot electron programming, by applying programming voltages to the gate and to either the left or the right region while the other region is grounded. Hot electrons are accelerated sufficiently to be injected into the region of the trapping dielectric layer near where the programming voltages were applied to. The device, however, is read in the opposite direction from which it was written, meaning voltages are applied to the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.