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US 6,639,844 B1Granted
Overerase correction method
AssigneeAdvanced Micro Devices, Inc.
InventorsZhizheng Liu, Yi He, Mark W. Randolph
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Abstract
A method for correcting overerasure in a multi-bit memory device. A sector of multi-bite memory cells in the device is erased and verified. After erase and verification, the overerased memory cells are soft programmed and verified to correct for overerasure. A soft programming pulse with a Vg to Vd ratio (Vg/Vd) greater than or equal to two is used.
Claims3
A method of overerase correction of flash memory cells in a multi-bit flash memory array, the method comprising:
- (a) programming all cells in a sector;
- (b) erasing and erase verifying all bits in the sector;
- (c) identifying overerased bits;
- and
- (d) applying a soft programming pulse having a ratio of Vg/Vd≧2 to overerased bits.
2 more elements
Dependencies are inferred from the claim text.