| 摘要 |
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 VGS of <3 volts, a VDS of <5 volts and a Vsub of <0 volts. The soft programming voltages are applied for a time period of <10 microseconds. The VT 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. |
