Measuring threshold voltage distribution in memory using an aggregate characteristic
US8073648B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 2007 |
| Grant date | Dec 6, 2011 |
| Priority date | — |
| Expiry date | Jul 9, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2211/5634
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A threshold voltage distribution of a set of storage elements in a memory device is measured by sweeping a control gate voltage while measuring a characteristic of the set of storage elements as a whole. The characteristic indicates how many of the storage elements meet a given condition, such as being in a conductive state. For example, the characteristic may be a combined current, voltage or capacitance of the set which is measured at a common source of the set. The control gate voltage can be generated internally within a memory die. Similarly, the threshold voltage distribution can be determined internally within the memory die. Optionally, storage elements which become conductive can be locked out, such as by changing a bit line voltage, so they no longer contribute to the characteristic. New read reference voltages are determined based on the threshold voltage distribution to reduce errors in future read operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.