| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To enable detection of excessive erase defect without using word line voltage being threshold voltage or less of the lowest limit of excessive erase. <P>SOLUTION: The semiconductor memory which can store information by difference of threshold voltage can perform first operation and second operation. In the first operation, a bit line to which a nonvolatile memory cell which is made an on-state by applying first voltage in which read is performed in read operation and made non-selection, to a plurality of word lines is connected, is detected. In the second operation, voltage of any one word line is made second voltage (Vdrb) being lower than first voltage for the plurality of word lines to which the first voltage is applied in the first operation, while voltage of residual word lines are made (Vuwb) being higher than the first voltage, when a state in which at least one bit line in which all nonvolatile memory cells sharing one bit line is made an off-state exists is detected, the word line made the second voltage in the state is specified as the word line having excessive erase defect. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
