| 摘要 |
In the conventional nonvolatile memory, it is not possible to determine the cause of the error is accidental or due to the degradation when the error is detect at the time of data read. Therefore, unnecessary substitute processing is performed, resulting in the exhaustion of the substitute area to shorten the life of the storage device. The semiconductor storage device according to the present invention determines the cause of an error at the time of the error correction of data read out from a nonvolatile semiconductor memory, on the basis of a previously recorded error correction count, and selects a data refresh processing or a substitute processing to perform. When the error is detected, the corrected data is rewritten back for preventing reoccurrence of error due to accidental cause. While, when it is determined that the reoccurrence frequency of the error is high and the error is due to degradation of the storage medium, based on the error correction count, the substitute processing is performed.
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