US Patent 7957198 Verifying an erase threshold in a memory device

In one or more embodiments, a memory device is disclosed as having an erase verify operation that includes a negative bias on the p-well in which the memory cell or cells being erased are formed. After an erase pulse is applied to the selected cells to be erased, the p-well is biased with the negative voltage and the erase verify operation is performed to determine the erased state of the cell(s).