| 摘要 |
PURPOSE:To enable programming at low voltage and low currents, and to obtain a nonvolatile semiconductor memory, which has the large efficiency of writing and is fitted to the increase of the degree of integration, by forming P type region in order to make injection-charge acceleration region steep only in the injection-charge acceleration region. CONSTITUTION:A selective gate electrode 15 and a floating gate electrode 14 are shaped in a channel region between a source region 12 and a drain region 13 in the surface of a P type semiconductor substrate 11 through gate insulating films 16, 17, and a control gate electrode 19 controls the potential of the floating gate electrode 14 through an insulating film 20. A high-concentration P type region 18 is formed only to the surface of the semiconductor substrate between the selective gate electrode 15 and the floating gate electrode 14, and an injection-charge acceleration region is shaped extremely steeply because the region 18 and both the electrode 15 and the electrode 14 hardly overlap. Drain voltage is applied effectively into the injection-charge acceleration region, thus enabling programming at low voltage and low currents. |
