Method and apparatus for bulk preprogramming flash memory cells with minimal source and drain currents
US5920506A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 26, 1997 |
| Grant date | Jul 6, 1999 |
| Priority date | — |
| Expiry date | Sep 26, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2216/16
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Apparatus is provided to facilitate the process of bulk preprogramming each of the cells in a flash memory or a subblock of a flash memory. In the process, the source and drain of each cell to be preprogrammed is biased such that current need not be flowing between the source and drain through the cell's channel region for charge to be transferred between the cell's channel region and the cell's floating gate. In a specific embodiment, the sources and drains are left floating without any particular bias voltage and the control gates of the cells are set to between 9 and 12 volts above the substrate and held there for about 10 milliseconds (ms). In an alternate embodiment, the sources and drains of all of the cells to be preprogrammed are biased to the same potential, which is a negative voltage, ground, or a positive voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.