| 摘要 |
PURPOSE: A semiconductor memory device and an erasing method thereof are provided to improve the efficiency of a preprogram by preprogramming only the cell string with memory cells with a low threshold voltage. CONSTITUTION: An erase command is inputted(S410). A selected memory block is pre-verified(S420). It is determined whether a pre-verification result is passed(S430). If the pre-verification result is passed, a hard is erased(S450). A soft program and a verification are performed(S460). |
