Patent ID: 8618526

Claim:
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; and a plug electrically connected to either the first electrode or 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.