| 摘要 |
PROBLEM TO BE SOLVED: To restore initial data even if other data is overwritten in the area where the initial data is stored. SOLUTION: In this semiconductor memory device having a memory cell for storing data by accumulating electric charges such as electrons and the like in a floating gate FG or by not accumulating, data desired to restore is stored by making the memory cell a first memory cell Q2 having a first charges exchange capability and a second memory cell Q3 having a second charges exchange capability. A memory cell can be made a different threshold voltage state conforming to different electric charges exchange capability of memory cells by erasing a whole plane of a memory cell, and initial data desired to restore can be read out. |
