Phase-change memory device and method of fabricating the same

Abstract

A phase-change memory device includes a lower electrode; and at least two phase-change memory cells sharing the lower electrode. Another phase-change memory device includes a heating layer having a smaller contact area with a phase-change material layer and a greater contact area with a PN diode structure.

1 . A method of fabricating a phase-change memory device, said method comprising:
 forming a lower electrode comprising a PN diode structure on an active region of a substrate;   forming a heating layer on the PN diode structure;   forming a phase-change material layer on the heating layer; and   forming an upper electrode on the phase-change material layer;   wherein a contact area between the phase-change material layer and the heating layer is formed to be smaller than that between the heating layer and the PN diode structure.   
     
     
         2 . The method of  claim 1 , wherein the heating layer is formed to have a cup shape by
 forming an insulating layer having an open region that exposes the top of the PN diode structure;   depositing a conductive layer of a predetermined thickness over the insulating layer including the open region; and   removing the conductive layer outside the open region while leaving the conductive layer of the predetermined thickness in the open region.   
     
     
         3 . The method of  claim 1 , wherein the heating layer is formed on the PN diode structure to have an exposed top surface, and the phase-change material layer is formed to be in electrical contact with only a part of the exposed top surface of the heating layer. 
     
     
         4 . A phase-change memory device, comprising:
 a substrate having thereon an active region;   a lower electrode comprising a PN diode structure on the active region of the substrate;   a heating layer on the PN diode structure;   a phase-change material layer on the heating layer; and   an upper electrode on the phase-change material layer;   wherein a contact area between the phase-change material layer and the heating layer is smaller than that between the heating layer and the PN diode structure.   
     
     
         5 . The device of  claim 4 , wherein the heating layer has a cup shape. 
     
     
         6 . The device of  claim 4 , wherein the phase-change material layer is in electrical contact with only a part of a top surface of the heating layer.