Ceiling test mode to characterize the threshold voltage distribution of over programmed memory cells
US6370061B1 · kind B1 · utility
Assignees
Inventors
Key dates
| Filing date | Jun 19, 2001 |
| Grant date | Apr 9, 2002 |
| Priority date | — |
| Expiry date | Jun 19, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/04
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The present invention relates to flash memory systems and methods to determine the threshold voltage of core cells. In one exemplary system, there is provided a method of characterizing the high end of the threshold voltage distribution of an array of programmed cells. In accordance with the invention, an exemplary system and method are presented to apply a varying characterization signal operably through a high breakdown voltage periphery donut transistor and wordline drive transistors, which are driven into saturation by a boosted gate voltage which is higher than the applied varying characterization signal, in a manner which provides for the accurate determination of the VT of the core cells, through the comparison of the conduction in a reference cell to that of the conduction in a core cell produced by a varying characterization signal applied to the core cell gate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.