| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a semiconductor storage device which can lower the voltage supplied to the diffusion layer and channel of a memory cell which is not selected actually for writing and can set the voltage of a nonselected word line to the optimum value against disturbance. SOLUTION: A semiconductor storage device is a 256M flash memory constituted in such a way that, in order to switch the voltages at a plurality of divided wells, a well decoder is added to an X-system and a well voltage is supplied to the well decoder from a power source circuit. At the time of precharging the storage device, a write inhibiting voltage Vpre+Vup is generated in a memory cell MC which is not selected for writing of a selected word line by precharging a source 12, a drain 13, and a channel 14 by using an internal voltage Vpre which is lower than a write inhibiting voltage and boosting the potentials at the source 12, drain 13, and channel 14 by switching the potentials at the wells.</p> |
