| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for initializing a non-volatile semiconductor storage that can be rewritten electrically to reduce the fluctuation of a threshold voltage, and at the same time to prevent abnormal operation, problems regarding reliability, and the increase in erasure time. SOLUTION: A method includes process 101 for repeating erasure operation and erasure verification and performing excessive erasure until a lower value as compared with a desired threshold voltage is reached, writing back process 102 for repeating verification for checking writing back operation and the lower limit of the threshold voltage and executing the threshold voltage until a desired value is reached, and verification process 103 for verifying that the upper limit of the threshold voltage at that time is equal to or smaller than a value. In the method, the processes 101, 102, and 103 are performed in this order.</p> |
