Forming nonvolatile memory elements by diffusing oxygen into electrodes

A method of forming a nonvolatile memory element, the method comprising:

• forming a first layer, the first layer comprising a first metal, wherein the first layer is operable as a first electrode;
• forming a second layer, the second layer comprising an oxide of a second metal that is more electronegative than the first metal;
• and
• forming a third layer, the third layer comprising an oxygen resistant material, wherein the third layer is operable as a second electrode, and wherein the second layer is positioned between the first layer and the third layer;
• annealing the first layer, the second layer, and the third layer at a temperature of between 250° C. and 400° C.;
• wherein oxygen diffuses from the second layer into the first layer but substantially no oxygen diffuses from the second layer into the third layer;
• wherein the second layer exhibits resistance switching characteristics after annealing;
• and
• wherein, after the annealing, a concentration of oxygen vacancies in the second layer is uneven.

A nonvolatile memory element comprising:

• a first layer comprising a first metal and an oxide of the first metal, wherein the first layer is operable as a first electrode;
• a second layer comprising an oxide of a second metal that is more electronegative than the first metal, wherein the oxide of the second metal comprises oxygen vacancies at least at an interface between the second layer and the first layer such that the second layer is operable as a resistance switching layer;
• and
• a third layer comprising an oxygen resistant material, wherein the third layer is operable as a second electrode, and wherein the second layer is positioned between the first layer and the third layer.