| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a nonvolatile semiconductor storage device capable of avoiding such a situation that the threshold voltage of a memory transistor rises to a read-out voltage or higher due to an influence of read-out disturbance. <P>SOLUTION: When data of logical state "1" are stored in a memory cell, the threshold voltage of the memory transistor MQ is set to the threshold voltage Ve or lower, which are lower than a read-out voltage Vr. A detection circuit 9 detects whether the threshold voltage of the memory transistor MQ being initially set to the threshold voltage Ve or lower is unintentionally fluctuated upward or not, by applying a voltage Vx which is higher than the threshold voltage Ve but lower than the read-out voltage Vr, between a semiconductor substrate 50 and a control electrode 56. <P>COPYRIGHT: (C)2009,JPO&INPIT |
