Patent ID: 7755075

Claim:
A phase-change memory device comprising: a different-material contact plug having a first electrically conductive material plug made of a first electrically conductive material, and a second electrically conductive material plug made of a second electrically conductive material having a specific resistance smaller than said first electrically conductive material, said first electrically conductive material plug and said second electrically conductive material plug being embedded in a common contact hole; a heater electrode having one end connected to said first electrically conductive material plug; a phase-change layer having a bottom surface including a portion connected to the other end of said heater electrode; an extension electrode layer held in contact with a portion of the bottom surface of said phase-change layer in an area displaced off a position directly above a contact surface through which said phase-change layer and said heater electrode contact each other; and a contact electrode connected to a portion of an upper surface of said extension electrode layer.