Nand nonvolatile semiconductor memory

A NAND nonvolatile semiconductor memory comprising:

• a plurality of series-connected memory cells each comprising a charge storage layer and control gate electrode,
• a plurality of word lines respectively connected to control gate electrodes of the memory cells,
• a first selection transistor connected between one end of the memory cells and a source line,
• a second selection transistor connected between the other end of the memory cells and a bit line, and
• a driver configured to control voltages applied to the plurality of word lines,
• wherein the driver applies a first voltage to a first word line connected to a selected memory cell, makes a second word line arranged on the source line side of the first word line float, applies a second voltage lower than the first voltage to a third word line adjacent to the second word line on the source line side, and applies a cutoff voltage that cuts off a channel of a memory cell to a fourth word line adjacent to the third word line on the source line side during a write operation.

A NAND nonvolatile semiconductor memory comprising:

• a plurality of series-connected memory cells each comprising a charge storage layer and control gate electrode,
• a plurality of word lines respectively connected to control gate electrodes of the memory cells,
• a first selection transistor connected between one end of the memory cells and a source line,
• a second selection transistor connected between the other end of the memory cells and a bit line, and
• a driver configured to control voltages applied to the plurality of word lines,
• wherein the driver applies a second voltage lower than a first voltage to a second word line arranged on the source line side of a first word line connected to a selected memory cell, and applies a cutoff voltage that cuts off a channel of a memory cell to a third word line adjacent to the second word line on the source line side after applying the first voltage to the first word line during a write operation.