| 摘要 |
Each memory cell of a nonvolatile semiconductor memory, essentially, consists of a one-transistor type memory cell such as a MOSFET having a floating gate electrode. When an electric programming operation is carried out, a positive voltage is applied to an n type drain region, a negative voltage is applied to a control gate and a source region is grounded. When an erasing operation is carried out, the positive voltage is applied to the control gate while all the other electrodes and a semiconductor substrate are grounded. Low power consumption can be accomplished because both of the programming operation and erasing operations are carried out by utilizing a tunneling mechanism. Furthermore, because the negative voltage applied to the word line, a drain voltage at the time of programming of data can be lowered, so that degradation of a gate oxide film at a channel portion can be mitigated.
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