| 摘要 |
PURPOSE: A method for erasing a flash memory device is provided to determine whether an erasing operation is normally performed or not by detecting a defective cell. CONSTITUTION: A pre-program(202) is performed to make all cells to be erased have the same threshold voltage. It is determined whether the pre-program is successively performed or not. About the cells to which a pre-program is successfully performed, an erasing operation is performed. If the erasing operation is successful, a post-program(218) is performed to restore over-erased cell to a desired threshold voltage. If the post-program(218) is successful, it is checked whether the erasing operation is successful or not. If the erasing operation is failed, the erasing operation is performed again. If the erasing operation is successful, the above steps are sequentially performed, an erasing operation fail counter is reset, and then the erasing operation is finished.
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