| 摘要 |
PURPOSE:To obtain a nonvolatile memory, especially a floating gate EEPROM, which is long-lived, whose area is small, whose density is high and whose reliability and reproducibility are excellent by a method wherein a control gate is formed on a floating gate via an insulating film and a region to generate a tunnel effect of an electric charge at a part of the insulating film. CONSTITUTION:Impurity doped regions 24 are formed on a substrate 21 on both sides of a floating gate 23 formed via a gate insulating film 22 on the substrate 21 ; a control gate 27 is formed on the floating gate 23 via an insulating film 26. A region 20 which can generate a tunnel effect of an electric charge is formed at least at a part of the insulating film 26 and between the control gate 27 and the floating gate 23. For example, a tunnel-effect generating region 20 which can easily generate a tunnel effect of an electric charge is formed at an insulating film 26 laid between a control gate 27 and a floating gate 23 in such a way that a thin film part is formed at a part on the side of a source region and a drain region 24, 25 so as to make the space between both gates 27, 23 small. Then, the erasure is executed at the tunnel-effect generating region 28.
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