Ramped gate technique for soft programming to tighten the Vt distribution
US6172909A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 9, 1999 |
| Grant date | Jan 9, 2001 |
| Priority date | — |
| Expiry date | Aug 9, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/3445
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method to tighten the threshold voltage distribution curve in a memory device composed of multiple memory cells organized in rows and columns by soft programming each memory cell. Soft programming voltages that utilize the hot-carrier mechanism are selected and are applied sequentially to memory cells in wordlines. The soft programming voltages include a ramped voltage V.sub.GS of <3 volts, a V.sub.DS of <5 volts and a V.sub.sub of <0 volts. The soft programming voltages are applied for a time period of <10 microseconds. The V.sub.T distribution is reduced to a maximum width of <2 volts. The soft programming is applied to the memory cells after the memory cells have been verified as having been erased and a having been overerase corrected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.