NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor storage device which achieves good controllability in a first insulation layer and which can reduce a leakage current from a second insulation layer due to a large coupling ratio, and which enables writing at low voltage.SOLUTION: A nonvolatile semiconductor storage device comprises a plurality of memory cells which can store data of more than binary. The memory cell includes a semiconductor layer 1B, a first insulation layer 2B on the semiconductor layer, a charge storage layer 3B on the first insulation layer, a second insulation layer 4B on the charge storage layer and a control gate electrode 5B on the second insulation layer. The second insulation layer 4B includes a ferroelectric layer. Further, polarized alignment pulse voltage is applied to the control gate electrode 5B before being read out.