Patent ID: 9390797
Filing Date: 2016-07-12
CPC Classification: G11C

Claim Text:
1. A method of driving a variable resistance element including a first electrode, a second electrode, and a metal oxide layer which is provided between the first electrode and the second electrode and changes its resistance value in response to a voltage pulse applied between the first electrode and the second electrode, wherein the metal oxide layer has a first oxide region connected to the first electrode, and a second oxide region connected to the second electrode and having a higher oxygen content atomic percentage than the first oxide region, the method comprising the steps of: applying a write voltage pulse of a first polarity between the first electrode and the second electrode to change a resistance state of the metal oxide layer from a higher-resistance state to a lower-resistance state to place the metal oxide layer in a write state; applying an erase voltage pulse of a second polarity which is different from the first polarity between the first electrode and the second electrode to change the resistance state of the metal oxide layer from the lower-resistance state to the higher-resistance state to place the metal oxide layer in an erase state; before the resistance value of the metal oxide layer first attaining a resistance value RL corresponding to the write state, changing the resistance value of the metal oxide layer from a resistance value R before the resistance value of the metal oxide layer first attaining the resistance value RL corresponding to the write state, applying a second initial voltage pulse of the second polarity between the first electrode and the second electrode, to change the resistance value of the metal oxide layer from the another resistance value R wherein when a maximum value of a current flowing through the metal oxide layer when the first initial voltage pulse is applied is IbRL, and a maximum value of the current flowing through the metal oxide layer when the write voltage pulse is applied is IRL, R |IRL|>|IbRL| are satisfied.