RESISTANCE CHANGE TYPE NONVOLATILE STORAGE AND ITS WRITING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a resistance change type nonvolatile storage configured to perform verification writing operation that combines improvement of precision of recording and retrieval of data with speed improvement in writing of data and its writing method.SOLUTION: A resistance change type nonvolatile storage performs verification writing operation configured to apply a voltage pulse to newly change a resistive state to a resistance change type element that fails to satisfy a criterion for checking that the resistive state has changed regardless of application of a voltage pulse for changing the resistive state. When the frequency of verification writing operation performed for a prescribed number of resistance change type elements to be a writing object exceeds a predetermined frequency, the storage waits for a prescribed time without applying an additional voltage pulse.