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

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 a side surface of the variable resistance layer which is connected to neither the first electrode nor the second electrode;
• and
• an interlayer insulating layer formed to cover the variable resistance layer and the side wall protecting layer,
• wherein the first variable resistance layer comprises a first metal oxide and a third metal oxide formed around the first metal oxide and having an oxygen deficiency lower than an oxygen deficiency of the first metal oxide, and the second variable resistance layer comprises a second metal oxide having an oxygen deficiency lower than the oxygen deficiency of the first metal oxide, and
• the side wall protecting layer covers at least a side surface of the third metal oxide to prevent oxygen in the interlayer insulating layer from diffusing into the third metal oxide.

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 a side surface of the variable resistance layer which is connected to neither the first electrode nor the second electrode;
• and
• an interlayer insulating layer formed to cover the variable resistance layer and the side wall protecting layer,
• wherein the first variable resistance layer comprises a first metal oxide and a third metal oxide formed around the first metal oxide and having an oxygen content atomic percentage higher than an oxygen content atomic percentage of the first metal oxide, and the second variable resistance layer comprises a second metal oxide having an oxygen content atomic percentage higher than the oxygen content atomic percentage of the first metal oxide, and
• the side wall protecting layer covers at least a side surface of the third metal oxide to prevent oxygen in the interlayer insulating layer from diffusing into the third metal oxide.

A nonvolatile memory element manufacturing method comprising:

• forming a laminated film including, as layers, a first electrode material, a first metal oxide, a second metal oxide, and a second electrode material in this order, the second metal oxide having an oxygen deficiency lower than an oxygen deficiency of the first metal oxide;
• patterning the laminated film to leave a portion of the laminated film to be a nonvolatile memory element, and remove an other portion of the laminated film;
• forming a third metal oxide around the first metal oxide by oxidizing a side surface of the first metal oxide exposed by the patterning, the third metal oxide having an oxygen deficiency lower than the oxygen deficiency of the first metal oxide;
• covering at least a side surface of the third metal oxide with a side wall protecting layer having oxygen barrier properties;
• and
• forming an interlayer insulating layer to cover the variable resistance layer and the side wall protecting layer,
• wherein the side wall protecting layer covers at least the side surface of the third metal oxide to prevent oxygen in the interlayer insulating layer from diffusing into the third metal oxide.

A nonvolatile memory device manufacturing method comprising:

• forming a plurality of first lines extending in a first direction;
• forming a first interlayer insulating layer covering the first lines;
• forming, in the first interlayer insulating layer, a plurality of first contact plugs that are connected to one of the first lines;
• forming, above the first contact plugs, a laminated film that is connected to the first contact plugs and includes, as layers, a first electrode material, a first metal oxide, a second metal oxide, and a second electrode material in this order, the second metal oxide having an oxygen deficiency lower than an oxygen deficiency of the first metal oxide;
• patterning the laminated film to leave a plurality of portions of the laminated film to be connected to the first contact plugs, and remove an other portion of the laminated film;
• forming a third metal oxide around the first metal oxide by oxidizing a side surface of the first metal oxide exposed by the patterning, the third metal oxide having an oxygen deficiency lower than the oxygen deficiency of the first metal oxide;
• covering at least a side surface of the third metal oxide with a side wall protecting layer having oxygen barrier properties;
• forming a second interlayer insulating layer covering the patterned laminated film and the side wall protecting layer;
• forming, in the second interlayer insulating layer, a plurality of second contact plugs that are connected to the patterned laminated film;
• and
• forming, above the second contact plugs, a plurality of second lines extending in a second direction different from the first direction,
• wherein the side wall protecting layer covers at least the side surface of the third metal oxide to prevent oxygen in the interlayer insulating layer from diffusing into the third metal oxide.