| 摘要 |
PURPOSE: A method for operating a nonvolatile memory is provided to reduce the malfunction of the nonvolatile memory by preventing the incorrect determination of a logic value of flag data. CONSTITUTION: A nonvolatile memory includes a plurality of memory cells which store data of multi bits. Threshold voltages of the plurality of the memory cells are included in one voltage distribution among first to fourth voltage distributions. If a first bit of the data is programmed in the plurality of the memory cells, it is checked whether a threshold voltage of a programmed flag cell is higher or lower than a confirmation voltage between the second voltage distribution and the third voltage distribution(S201). If the threshold voltage of the flag cell is lower than the confirmation voltage, the first bit of the data is programmed in the plurality of the memory cells(S202). [Reference numerals] (AA) Start; (BB) Yes; (CC) No; (DD) Finish; (EE) Is a threshold voltage of a flag cell higher than a confirmation voltage(R1) ?; (S201) Checking a threshold voltage of a flag cell using a confirmation voltage(R1); (S202) Programming a first bit in a memory cell
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