Nonvolatile semiconductor memory device and operation method thereof

Abstract

A nonvolatile semiconductor memory device according to one embodiment includes: a memory cell array; word lines; bit lines; and a control circuit configured to write multi-value data in the memory cells. The control circuit sets either even-ordinal-number bit lines or odd-ordinal-number bit lines as selected bit lines while setting the other as unselected bit lines; applies a write inhibiting voltage to the unselected bit lines; applies a write voltage to the selected bit lines corresponding to unwritten memory cells to be given one of threshold voltage distributions representing different written states; and applies the write inhibiting voltage to the selected bit lines corresponding to unwritten memory cells to be given any other of the threshold voltage distributions representing the different written states, memory cells already written, and memory cells to be maintained in a threshold voltage distribution representing an erased state, thereby executing a write operation.