Write method for writing to variable resistance nonvolatile memory element and variable resistance nonvolatile memory device

摘要

A write method for writing to a variable resistance nonvolatile memory element, comprising applying a set of strong recovery-voltage pulses at least once to the variable resistance nonvolatile memory element when it is determined that the resistance state of the variable resistance nonvolatile memory element fails to change to a second resistance state, remaining in a first resistance state, the set of strong recovery-voltage pulses including pulses: (1) a first strong recovery-voltage pulse which has a greater amplitude than a normal second voltage for changing the resistance state to the first resistance state, and has the same polarity as the second voltage; and (2) a second strong recovery-voltage pulse which follows the first strong recovery-voltage pulse and has a longer pulse width than the pulse width of the normal first voltage for changing the resistance state to the second resistance state, and has the same polarity as the first voltage.

主权项

1. A write method for writing to a variable resistance nonvolatile memory element for reversibly changing a resistance state of the variable resistance nonvolatile memory element by applying a voltage pulse to the variable resistance nonvolatile memory element,
the variable resistance nonvolatile memory element including a first electrode, a second electrode, and a variable resistance layer between the first electrode and the second electrode, the variable resistance layer including a first transition metal oxide layer in contact with the first electrode, and a second transition metal oxide layer in contact with the second electrode, the second transition metal oxide layer having a smaller oxygen deficiency than the first transition metal oxide layer, the variable resistance nonvolatile memory element having characteristics of changing the resistance state from a first resistance state for use in recording first information to a second resistance state for use in recording second information when a pulse of a first voltage is applied to the variable resistance nonvolatile memory element, and changing the resistance state from the second resistance state to the first resistance state when a pulse of a second voltage that has a polarity different from the first voltage is applied to the variable resistance nonvolatile memory element, the write method comprising: (a) determining whether the resistance state of the variable resistance nonvolatile memory element fails to change to the second resistance state, remaining in the first resistance state when the pulse of the first voltage is applied to the variable resistance nonvolatile memory element; and (b) applying a set of strong recovery-voltage pulses at least once to the variable resistance nonvolatile memory element when it is determined in step (a) that the resistance state of the variable resistance nonvolatile memory element fails to change to the second resistance state, remaining in the first resistance state, the set of strong recovery-voltage pulses including two pulses which are: a first strong recovery-voltage pulse having a greater amplitude than the second voltage and a same polarity as the second voltage; and a second strong recovery-voltage pulse which follows the first strong recovery-voltage pulse and has a longer pulse width than a pulse width of the first voltage and a same polarity as the first voltage.