Storage device and method of manufacturing storage device

A method of manufacturing a storage device, the method comprising:

• forming a state change layer on a substrate, the state change layer having a first resistance state and a second resistance state, the state change layer being switchable from one to the other of the first and second resistance states according to a magnitude of a voltage applied thereto;
• forming a first conductor on an upper surface of the state change layer, the first conductor comprising carbon;
• forming a second conductor on an upper surface of the first conductor;
• processing an upper surface of the second conductor to reduce roughness thereof;
• forming a first ferromagnetic material on the upper surface of the second conductor after the processing to the reduced roughness thereof;
• forming a nonmagnetic material on an upper surface of the first ferromagnetic material;
• and
• forming a second ferromagnetic material on an upper surface of the nonmagnetic material.

A method of manufacturing a storage device, the method comprising:

• forming a state change layer on a substrate, the state change layer having a first resistance state and a second resistance state switchable from one to the other of the first and second resistance states according to a magnitude of a voltage applied thereto;
• forming a conductor on an upper surface of the state change layer, the conductor comprising carbon;
• forming a buffer layer comprising a conductive material on an upper surface of the conductor, the buffer layer comprising a metal and having a lower surface with a first roughness and an upper surface with a second roughness that is less than the first roughness;
• forming a first ferromagnetic material on the upper surface of the buffer layer;
• forming a nonmagnetic material on an upper surface of the first ferromagnetic material;
• and
• forming a second ferromagnetic material on an upper surface of the nonmagnetic material.