| 摘要 |
PROBLEM TO BE SOLVED: To prevent erroneous erasure in a non-selection block and reduce degradation of a tunnel insulation film at the erasure of a selection block.SOLUTION: A preliminary erasure controller 13A applies a constant erasure voltage VE to a well side of a memory cell, to erase the memory cell in units of blocks B1-Bn, and an erasure controller 13B applies the voltage higher than that at the erasure time to a control gate electrode of the memory cell while applying a preliminary erasure voltage VPE to the well side of the memory cell before the erasure, to preliminarily erase the memory cell. |
