Nonvolatile semiconductor memory device and method for driving same

A nonvolatile semiconductor memory device, comprising

• a memory unit and a control unit,
• the memory unit including a plurality of strings,
• the strings having:
• a charge storage film;
• and
• a memory cell transistor provided for each of a plurality of storage regions configured to store charge in the charge storage film, a threshold of the memory cell transistor fluctuating due to data set in the storage region,
• the control unit being configured to:
• set the memory cell transistors to an erase threshold by setting erase data in the plurality of storage regions of at least one of the strings;
• subsequently set the memory cell transistors provided in the storage regions to thresholds corresponding to data having n (n being an integer not less than 2) values by programming the data having the n values to at least one of the storage regions of the strings in which the erase data is set;
• and
• control data of at least one storage region before being programmed adjacent to the storage regions programmed with the data to have a value providing a threshold of the memory cell transistor nearer than the erase threshold to the thresholds corresponding to the data having the n values in the state of the memory cell transistors provided in the storage regions being set to the thresholds corresponding to the data having the n values.