Nonvolatile semiconductor memory device capable of storing multi-value data of more than one bit in a memory cell

摘要

A nonvolatile semiconductor memory device includes a memory cell including a charge storage section for storing n-value data (n>/=3). In this device, the charge storage section has discrete first to n-th charge amount regions for storing the n-value data. If the first to n-th charge amount regions are defined as n-th, (n-1)-th, . . . , (i+1)-th, i-th charge amount regions in descending order of an amount of positive or negative charge stored in the charge storage section, a charge amount difference DELTA Mj between a j-th charge amount region and a (j-1)-th charge amount region is set to DELTA Mn> DELTA Mn-1> . . . > DELTA Mi+2> DELTA Mi+1.