| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor storage device capable of suppressing the influence of deterioration of a memory cell during an erasure operation and a software program operation. <P>SOLUTION: A nonvolatile semiconductor storage device relating to one embodiment includes a control part. The control part manages repetitive control over an erasure operation for applying an erasure voltage to a memory cell within a predetermined range for data erasure, an erasure verify-operation for confirming whether the data erasure is completed, and a step-up operation for making the erasure voltage increase only by a predetermined step-up value when the data erasure is not completed. The control part is configured so as to execute a software program operation for setting the memory cell within the predetermined range from an excessive erasure state to a first threshold voltage distribution state in the case that the number of times of applying the erasure voltage during a series of erasure operations is more than a first number of times and is less than a second number of times (the first number of times<the second number of times), and so as not to execute the software program operation in the case that the number of times of applying the erasure voltage is the first number of times or below, or the second number of times or more. <P>COPYRIGHT: (C)2013,JPO&INPIT |
