| 摘要 |
A semiconductor memory device having a self-correcting function comprises a plurality of non-volatile memory cells (2) and first and second read circuits (5, 6) for reading bit data from the memory cells. Part of the memory cells (1a) store data, whereas another part (1b) store parity bits on the data. Each memory cell (2) selectively stores "0" or "1" by causing itself to be charged with an electric charge. The first and second read circuits (5, 6) receive a plurality of bit data from a plurality of selected memory cells in order to output correct data with correct parity. The criteria of detecting "0" and "1" in the first and second read circuits (5, 6) are set to different values, so that the first read circuit (5) detects a current value smaller than the value of the current flowing through the memory cell holding a bit error because of charge depletion, whereas the second read circuit (6) detects a current value greater than that value. Consequently, even if the variation of the threshold resulting from the charge depletion allows the presence of a faulty memory cell therein, one of the read circuits (5, 6) can make correct data read. |
