Semiconductor integrated circuit and data processing system
US6459621B1 · kind B1 · utility
Assignees
Inventors
Key dates
| Filing date | Aug 17, 2001 |
| Grant date | Oct 1, 2002 |
| Priority date | — |
| Expiry date | Aug 17, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2211/5642
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A control of a flash memory includes control for supplying a pulse-shaped voltage to each of non-volatile memory cells until a threshold voltage of the non-volatile memory cell having a first threshold voltage is changed to a second threshold voltage. The control involves a first write mode (coarse write) in which the amount of change in threshold voltage of each non-volatile memory cell, which is varied each time the pulse-shaped voltage is applied, is relatively rendered high, and a second write mode (high-accuracy write) in which the amount of change in threshold voltage thereof is relatively rendered low. As compared with the high-accuracy mode, the number of pulses required to change the threshold voltage of each memory cell is smaller than that in the coarse write mode. Therefore, the number of verify operations at the time that the coarse write mode is used, is small and hence the entire write operation can be speeded up.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.