| 摘要 |
<p>PURPOSE: To improve the characteristics and reliability of a semiconductor storage device by making selection gate signals, SGD and SGS, higher than Vcc at the time of erasing the semiconductor storage device so that the transistor for transfer gate is cut off. CONSTITUTION: Control gate signals, CGo to CG15, are set at Vss(OV) for erasing, and selection gate signals, SGD and SGS, at Vcc-Vth. Vcc is an externally fed voltage and made at 5V or lower. When the transfer gate signal TGi of selection block BLKi becomes Vcc, transistors, T2i to T17i, become conducting, and control gates, CGoi to CG15i, are brought to be at Vss(OV). Consequently, when the P well and N well of the memory cell section are brought to be at a high voltage Vpp, the data of the memory cell of a selection block BLKi is erased to become data '1'. When the P well of the memory cell section becomes Vpp, the potentials of SGDi and SGSi also become Vcc-Vth+Vpp, protecting and not destroying the oxide film of the selection gate.</p> |
