| 摘要 |
A reliable Flash EPROM in which a band-to-band tunneling current is suppressed. A memory cell is formed on a double well structure region. A second impurity region of a first conductivity type formed in a first impurity region of a second conductivity type on a semiconductor substrate of the first conductivity type. A gate oxide film, a floating gate, an insulating film and a control gate are laminated in this order on a surface of the second impurity region, thereby forming a laminated gate. Source and drain regions are formed in a surface region of the second impurity region with the laminated gate interposed therebetween. The EPROM comprises a voltage supply system to suppress a band-to-band tunneling current. To discharge the floating gate, the semiconductor substrate is grounded and a potential difference between one of the source and drain regions and the second impurity region of the first conductivity type is controlled to be greater than 0 V and smaller than 2.5 V.
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