Multi-level non-volatile semiconductor memory device having improved multi-level data storing circuits

摘要

A multi-value storing EEPROM having data-storing circuits, each storing a control data item which determines a write-control voltage to be applied to one bit line in order to write data into any memory cell connected to the bit line. The write-control voltage is applied to the bit line to write data into the memory cell, on the basis of the control data item stored in the data-storing circuit. To read the data from the cells, a bit-line signal is supplied to the bit line in accordance with the control data item stored in the data-storing circuit. To achieve write verification, the value of the bit-line signal on the bit line is detected from the data-storing state the memory cell assumes. The control data item stored in the circuit can be changed on the basis of the data- storing state of the memory cell.