| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a non-volatile semiconductor memory in which distribution of threshold values is made narrow, operation speed is increased, operation voltage is made low, and which is suitable for a memory cell. SOLUTION: In a non-volatile semiconductor memory consisting of memory cells M01-M32, bit lines BL0-BLn connected to drains of cells, word lines W0-Wn connected to control gates of cells, cell source lines 1 connected to sources of cells, reference cells MR provided corresponding to cells. and a sense amplifier 3 comparing a current Im of a selected bit line with a reference current Ir, a cell well line 2 connected to a well of a cell is provided, in order to make distribution of threshold values of cells after erasing data the prescribed distribution, when a cell of a low threshold value being over-erased is detected, the prescribed bias voltage is applied to a cell source line 1, while a potential of a cell well line is made equal to a potential of the cell source line 1, and a cell of a low threshold value is detected by comparing the Im with the Ir.</p> |
