Nonvolatile memory element, nonvolatile memory device, nonvolatile memory element manufacturing method, and nonvolatile memory device manufacturing method

1. A nonvolatile memory element comprising:

a first electrode;

a second electrode;

a variable resistance layer that is between the first electrode and the second electrode and includes, as stacked layers, a first variable resistance layer connected to the first electrode and a second variable resistance layer connected to the second electrode, the variable resistance layer having a resistance value that reversibly changes based on an electrical signal applied between the first electrode and the second electrode;

a side wall protecting layer that has oxygen barrier properties and covers at least a side surface of the variable resistance layer and a side surface of the first electrode; and

an interlayer insulating layer formed to cover at least the side wall protecting layer,

wherein the first variable resistance layer comprises a first transition metal oxide and a third transition metal oxide formed around the first transition metal oxide and having an oxygen deficiency lower than an oxygen deficiency of the first transition metal oxide, and the second variable resistance layer comprises a second transition metal oxide having an oxygen deficiency lower than the oxygen deficiency of the first transition metal oxide,

wherein the second variable resistance layer comprises a first side and a second side,

wherein the first side of the second variable resistance layer is in physical contact with the second electrode, and

wherein the second side of the second variable resistance layer is in physical contact with the first transition metal oxide and the third transition metal oxide.

2. The nonvolatile memory element according to claim 1 ,

wherein the side wall protecting layer comprises one of a metal oxide, a metal nitride, and a metal acid nitride that have insulation properties and oxygen barrier properties.

3. The nonvolatile memory element according to claim 1 ,

wherein the side wall protecting layer comprises one of a silicon nitride, an aluminum oxide, and a titanium oxide.

4. The nonvolatile memory element according to claim 1 ,

wherein the first transition metal oxide has a stack structure of a plurality of layers comprising metal oxides having different oxygen deficiencies.

5. The nonvolatile memory element according to claim 1 ,

wherein each of the first transition metal oxide, the second transition metal oxide, and the third transition metal oxide is one of a tantalum oxide, a hafnium oxide, and a zirconium oxide.

6. The nonvolatile memory element according to claim 1 ,

wherein the second variable resistance layer is provided with a localized region having an oxygen deficiency, the localized region configured to reversibly change the oxygen deficiency in response to an application of an electric pulse.

7. The nonvolatile memory element according to claim 1 , wherein the side wall protecting layer further covers at least a side surface of the second transition metal.

8. The nonvolatile memory element according to claim 1 ,

wherein the side wall protecting layer further covers at least a side surface of the second electrode.

9. The nonvolatile memory element according to claim 8 ,

wherein the side wall protecting layer further covers at least a top surface of the second electrode.