Method for forming asymmetric flash EEPROM with a pocket to focus electron injections
US6130134A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 14, 1998 |
| Grant date | Oct 10, 2000 |
| Priority date | — |
| Expiry date | Aug 14, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/26586
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A memory cell having an asymmetric source and drain connection to virtual ground bit-lines. A main diffusion, adjacent the drain and displaced from the source, allows Fowler-Nordheim (FN) tunneling erasure on the drain side of the floating gate. A pocket diffusion, between the main diffusion and the source, concentrates the electric field and thereby enhances the efficiency of programming by electron injection on the source side of the floating gate. A nonvolatile semiconductor memory device comprising row and column arrangement of the cells, in which adjacent columns of cells share a single virtual ground bit line. The method for manufacturing a memory cell having asymmetric source and drain regions and comprising the steps of: (1) forming a semiconductor substrate having a first conductivity type; (2) forming a dielectric covering a semiconductor substrate; (3) forming a first and second column of floating gates on the dielectric; (4) implanting a first dopant along a first dopant strip, the first dopant strip aligned adjacent the first column and displaced from the second column and having a second conductivity type opposite the first conductivity type; (5) implanting a second d…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.