Patent ID: 8872148

Claim:
A phase-change memory device, comprising: a diode disposed on an upper surface of a substrate; a heating element disposed on the diode, the heating element having a lower part of metal or a metallic compound disposed on the diode so as to receive current from the diode, and an upper part capable of converting current supplied thereto from the lower part to Joule's heat, the lower part having a bottom surface that faces towards the diode and a top surface, the upper part having a bottom surface that faces towards the top surface of the lower part, the area of the bottom surface of the upper part being equal to the area of the top surface of the lower part, and the upper part being of substantially the same metal or metallic compound as the lower part and containing a dopant of impurities by which the resistance of the upper part is made greater than that of the lower part; a phase-change layer pattern disposed directly on the upper part of the heating element, wherein the upper part of the heating element serves as a heater for the phase-change layer pattern, and the phase-change layer pattern comprises material whose state can be selectively changed under the control of the heater; an upper electrode disposed on the phase-change layer pattern; and first and second insulating layers disposed on the substrate and having a respective opening extending therethrough, and wherein the diode occupies a lower portion of the opening in the first insulating layer, the heating element occupies an upper portion of the opening in the first insulating layer, and the phase-change layer pattern is disposed in the opening in the second insulating layer, wherein the lower part of the heating element is a plug of metal selected from the group consisting of tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), hafnium (Hf), zirconium (Zr), chrome (Cr), niobium (Nb), and vanadium (V), the heating element further comprises a barrier layer of a metal or a metallic nitride interposed between the plug and the diode, between the plug and the first insulating layer, and between the upper portion of the heating element and the first insulating layer, the diode and the barrier layer have laterally outer surfaces, respectively, that are contiguous with one another, the upper part of the heating element containing the impurities and the phase-change layer pattern have top and bottom surfaces, respectively, that contact each other, the area of the top surface of the upper part of the heating element being larger than the area of the bottom surface of the phase-change layer pattern.