| 摘要 |
PURPOSE: A semiconductor memory device and an operating method thereof are provided to be able to improve the erase threshold voltage distribution by grouping multiple word lines of memory cell blocks and performing an erasing operation according to each word ling group. CONSTITUTION: The whole erase operation is performed so that the threshold voltages of all memory cells connected to even word lines and odd word lines within selected memory cell blocks are lower than a first target level (310). The erase operation is performed so that the threshold voltages of the memory cells connected to even word lines are lower than a second target level which is lower than the first target level (320). The erase operation is performed so that the threshold voltages of the memory cells connected to odd word lines are lower than the second target level (330). [Reference numerals] (AA) Start; (BB,DD,FF) No; (CC,EE) Yes; (GG) End; (S301) First removal of selected block; (S302) First removal pass?; (S303,S306,S309) Removal voltage increase; (S304) Second removal of first word line group; (S305) Second removal pass?; (S307) Third removal of second word line group; (S308) Third removal pass? |
