| 摘要 |
The non-volatile semiconductor memory disclosed includes an X-decoder and word line potential supply circuits, and a current setting/holding circuit. The X-decoder and the word line potential supply circuits set all word lines ground potential in the flash erasing operation, to a predetermined first over-erasing judgment reference potential in an "on" cell detecting operation, and to a predetermined second over-erasing judgment reference potential for judgment of over-erasing deeper than the first over-erasing judgment reference potential and, in an "on" cell specifying operation, set predetermined selected word lines to the first over-erasing judgment reference potential while setting other word lines than the selected word line to the second over-erasing judgment reference potential. The current setting/holding circuit sets the reference current in an "on" cell specifying reference current setting operation such that the result of the check by a sense amplifier is "on". It is possible to eliminate the possibility of generation of a memory cell transistor in a non-erased state, thus ensuring quick operation.
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