| 摘要 |
PURPOSE:To increase the number of rewriting times, by using a tunnel heat nitriding oxidation film as a tunnel insulation film where electrons inside a floating gate electrode formed of a polycrystalline silicon layer are discharged to an erasing electrode. CONSTITUTION:An N<+> type source region 12 and an N<+> type drain region 13 are formed on a surface of a P type silicon substrate 11, and a floating gate electrode 15 made of a polycrystalline silicon layer is formed with a gate insulation film 14 in between. A controlling gate electrode 17 for use in controlling a potential of this memory is formed with an insulation film 16 in between. Further an erasing electrode 19 is formed with a tunnel heat nitriding oxidation film 18 in between. In the case of a writing operation, a high voltage is applied to the controlling gate electrode 17 and the N<+> type drain region 13, and next the N<+> type source region 12 is earthed, so that hot electrons produced are injected into the floating gate electrode 15. In the case of an erasing operation, a positive high voltage is applied to the erasing electrode 19, and the electrons inside the floating gate electrode 15 are discharged through the tunnel heat nitriding oxidation film 18 by means of Fowler-Nordheim tunneling. Hence, a rewriting characteristic of a non-volatile memory can be much improved.
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