| 摘要 |
<p>PURPOSE:To provide a nonvolatile semiconductor memory device in which the rewriting of data can be electrically performed and the size of a memory cell can be reduced by injecting or discharging electrons into the floating gate of a cell transistor through an insulating film. CONSTITUTION:A signal R is set to a level of '0' to bring a transistor 27 into a off-state, and signals X1 and W1 to W4 are set to a high level at the timing of t0 to inject electrons into the floating gate of cell transistors CT1 to CT4 through a thin oxide film 33 and then sequentially set the signals W4 to W1 to OV at the following timing t1 to t4. At that time, if data D outputted from a data input circuit 25 is in a level of '1', a transistor 26 is turned on to apply a high voltage to the corresponding drain through the transistor 26 and a selecting transistor ST from a high-voltage power supply Vp, and electrons are discharged from a floating gate by the tunnel effect. As a result, data can be selectively programmed into each cell transistor.</p> |
