Nonvolatile semiconductor memory including multi-threshold voltage memory cells including voltage ranges indicating either an erase state or a two or more program state

摘要

In a nonvolatile semiconductor memory device wherein a plurality of threshold voltages are set so as to store multi-valued information in one memory cell, data is first written into the memory cell whose threshold voltage is the lowest as a written state from the erase level, and data is successively written into memory cells whose threshold voltages are higher.