| 摘要 |
PURPOSE:To realize low program voltages without degrading holding characteristics by applying a constant voltage smaller than source voltage upon program electrodes serving also as read output electrodes. CONSTITUTION:When a reverse bias (write) voltage is applied to a control gate area 37 of n type capacitive-coupled strongly via an insulation film 38 to a floating gate electrode 35 in the case of a p type substrate 31, the surface of the substrate 31 under the film 48 depletes or inverts. Further, when a forward current is injected to the substrate 31 from an electron injector region 36 of n type as shown by an arrow D, part of said current enters the electrode 35. To erase this, a thin insulation film region 45 is provided between the electrode 35 and a drain region 33, and when a positive voltage (erasing voltage) is applied to the region 37, a tunnel current flows in the film 45, and the electrons in the electrode 35 flows out into the region 33. To read out, a constant voltage (source voltage) is applied to the region 37, and the read out is accomplished by the current between the source and drain regions flowing dependently upon the electron density in the electrode 35. |
