Phase change memory devices, methods of manufacturing and methods of operating the same

A method of manufacturing a phase change memory device, the method comprising:

• forming a storage node connected to a switching device, the forming of the storage node including,
• forming a first phase change layer on an insulating interlayer, the first phase change layer being formed to cover an exposed surface of a bottom electrode contact layer,
• forming a first material layer on a first region of the first phase change layer, the first material layer being formed to cover the exposed surface of the bottom electrode contact layer, and the first material layer having a lower electric conductivity than an amorphous region of the first phase change layer, and
• forming a second phase change layer on the first phase change layer, the second phase change layer being formed to cover the first material layer.

A method of manufacturing a phase change memory device including a switching device and a storage node connected to the switching device, the method comprising:

• forming the storage node, wherein the forming of the storage node includes,
• forming a phase change layer on an insulating interlayer to cover an exposed surface of a bottom electrode contact layer,
• forming a trench over the exposed surface of the bottom electrode contact layer in the phase change layer, the trench having a bottom surface with at least the same area as the exposed surface of the bottom electrode contact layer,
• filling the trench with a material layer, and
• forming a top stack on the phase change layer and the material layer, the material layer having a lower electric conductivity than an amorphous region to be formed in the phase change layer.