| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a nonvolatile semiconductor memory device in which a write operation and a read operation can be performed normally even when an excessively erased memory cell is generated by a method wherein the source potential of a memory cell which is connected across a bit line selected in the write operation and the read operation and a word line which is not selected is kept at the same potential as the potential of the bit line and the source potential of a memory cell which is connected across the selected bit line and the word line is kept at a ground potential. SOLUTION: When a write operation is performed to a memory cell 34, a word line 20 and a bit line 22 are selected. The word line 20 is controlled to 12 V, word lines 17 to 19 which are not selected are controlled to 0 V, the bit line 22 is controlled to 7 V, bit lines 21, 23 which are not selected are controlled to an open state, a source power supply VS 32 is controlled to 0 V, and a source power supply VB 29 is controlled to 7 V. The drain voltage of the memory cell 34, to be written, among from memory cells 13, 33, 15, 34 on the bit line 22 is 7 V, and its source voltage is 0 V. The drain voltage and the source voltage of memory cells which are not selected are 7 V. Even in an excessively erased memory cell, a current does not flow to a source diffusion interconnection from the bit line 22.</p> |
