Nonvolatile memory device and manufacturing method thereof

A nonvolatile memory device comprising:

• a nonvolatile memory element provided on a substrate, and including a first electrode, a second electrode, and a resistance variable layer provided between the first electrode and the second electrode, resistance values of the resistance variable layer changing reversibly in response to electric signals applied between the first electrode and the second electrode, the nonvolatile memory element having a stacked-layer structure in which the first electrode, the second electrode and the resistance variable layer are stacked together such that the first electrode, the second electrode and the resistance variable layer are parallel to a main surface of the substrate and are planarized;
• a plug electrically connected to either the first electrode or the second electrode of the nonvolatile memory element;
• a first wire formed within a plane parallel to the main surface of the substrate;
• and
• a second wire formed within a plane different from the plane of the first wire;
• one of the first wire and the second wire is electrically connected to one of the first electrode and the second electrode of the nonvolatile memory element via the plug, and the other of the first wire and the second wire is directly electrically connected to the other of the first electrode and the second electrode of the nonvolatile memory element;
• wherein the resistance variable layer includes an oxygen-deficient first transition metal oxide layer and a second transition metal oxide layer having a higher oxygen content than the first transition metal oxide layer;
• the first transition metal oxide layer is connected to one of the first electrode and the second electrode, and the second transition metal oxide layer is connected to the other of the first electrode and the second electrode;
• and
• an area of an end surface of the plug at which the plug and the nonvolatile memory element are connected together, the end surface being parallel to the main surface of the substrate, is greater than a cross-sectional area of a cross-section of the first transition metal oxide layer which is an electrically-conductive region, the cross-section being parallel to the main surface of the substrate.

A method of manufacturing a nonvolatile memory device, comprising:

• a step A of forming at least a wire and a plug connected to the wire, on a substrate;
• and
• a step B of forming above the plug, a stacked-layer structure including a first electrode, a second electrode located above the first electrode, and a resistance variable layer provided between the first electrode and the second electrode, resistance values of the resistance variable layer changing reversibly in response to electric signals applied between the first electrode and the second electrode, the stacked-layer structure having a stacked-layer structure in which the first electrode, the second electrode and the resistance variable layer are stacked together such that the first electrode, the second electrode and the resistance variable layer are parallel to a main surface of the substrate and are planarized;
• wherein the step B includes, to form the resistance variable layer, a step b1 of forming an oxygen-deficient first transition metal oxide layer connected to one of the first electrode and the second electrode;
• a step b2 of forming a second transition metal oxide layer connected to the other of the first electrode and the second electrode and having a higher oxygen content than the first transition metal oxide layer;
• and a step b3 of forming the plug and/or the stacked-layer structure such that an area of an end surface of the plug at which the plug and the stacked-layer structure are connected together, is greater than a cross-sectional area of a cross-section of the first transition metal oxide layer which is an electrically-conductive region, the cross-section being parallel to the main surface of the substrate.

A method of manufacturing a nonvolatile memory device, comprising:

• a step A of forming at least a first wire and a plug connected to the first wire, on a substrate;
• a step B of forming above the plug, a stacked-layer structure including a first electrode, a second electrode located above the first electrode, and a resistance variable layer provided between the first electrode and the second electrode, resistance values of the resistance variable layer changing reversibly in response to electric signals applied between the first electrode and the second electrode, the stacked-layer structure having a stacked-layer structure in which the first electrode, the second electrode and the resistance variable layer are stacked together such that the first electrode, the second electrode and the resistance variable layer are parallel to a main surface of the substrate and are planarized;
• and
• a step C of forming a second wire within a plane parallel to the main surface of the substrate above the stacked-layer structure and the plug;
• wherein the step B includes, to form the resistance variable layer, a step b1 of forming an oxygen-deficient first transition metal oxide layer connected to one of the first electrode and the second electrode;
• a step b2 of forming a second transition metal oxide layer connected to the other of the first electrode and the second electrode and having a higher oxygen content than the first transition metal oxide layer;
• and a step b3 of forming the plug and/or the stacked-layer structure such that an area of an end surface of the plug at which the plug and the stacked-layer structure are connected together, is greater than a cross-sectional area of a cross-section of the first transition metal oxide layer which is an electrically-conductive region, the cross-section being parallel to the main surface of the substrate;
• and
• the step C includes, to form the second wire, a step c1 of forming an insulating layer such that the insulating layer covers the stacked-layer structure;
• a step c2 of removing a portion of the insulating layer such that the stacked-layer structure is exposed, to form a wire trench on the stacked-layer structure;
• and a step c3 of forming the second wire into the wire trench.