Phase change memory devices and methods of manufacturing the same

Abstract

A phase change memory device includes a phase change memory unit and a heat sink. The phase change memory unit includes a phase change material layer pattern, a lower electrode beneath the phase change material layer pattern configured to heat the phase change material layer pattern, and an upper electrode on the phase change material layer pattern. The heat sink configured to absorb heat from the phase change memory unit. The heat sink has a top surface lower than a top surface of the upper electrode and is spaced apart from the phase change memory unit.

What is claimed is: 
     
         1 . A phase change memory device, comprising:
 a phase change memory unit, including:
 a phase change material layer pattern; 
 a lower electrode beneath the phase change material layer pattern, the lower electrode configured to heat the phase change material layer pattern; and 
 an upper electrode on the phase change material layer pattern; and 
   a heat sink configured to absorb heat from the phase change memory unit, the heat sink having a top surface lower than a top surface of the upper electrode and being spaced apart from the phase change memory unit.   
     
     
         2 . The phase change memory device of  claim 1 , wherein the heat sink includes a metal, and wherein the phase change memory device further includes an insulation layer electrically insulating the heat sink from the phase change memory unit. 
     
     
         3 . The phase change memory device of  claim 2 , wherein the heat sink includes titanium nitride. 
     
     
         4 . The phase change memory device of  claim 1 , wherein the top surface of the heat sink is lower than a bottom surface of the upper electrode. 
     
     
         5 . The phase change memory device of  claim 1 , wherein the top surface of the heat sink is higher than a top surface of the lower electrode. 
     
     
         6 . The phase change memory device of  claim 1 , wherein a bottom surface of the heat sink is lower than a bottom surface of the lower electrode. 
     
     
         7 . The phase change memory device of  claim 1 , further comprising
 a contact plug on the lower electrode;   wherein a bottom surface of the heat sink is lower than a top surface of the contact plug.   
     
     
         8 . The phase change memory device of  claim 1 , wherein a bottom surface of the phase change material layer pattern has a shape and an area substantially the same as those of the lower electrode. 
     
     
         9 . The phase change memory device of  claim 1 , wherein a bottom surface of the lower electrode has an area larger than that of a top surface of the lower electrode. 
     
     
         10 . The phase change memory device of  claim 8 , wherein the lower electrode has a vertical cross-section that is substantially an “L” shape. 
     
     
         11 . The phase change memory device of  claim 1 , further comprising:
 a plurality of word lines arranged in a first direction, each word line extending in a second direction substantially perpendicular to the first direction;   a plurality of diodes arranged in the second direction overlying corresponding ones of the plurality of word lines; and   a plurality of bit lines, each bit line extending in the first direction;   wherein:
 the upper electrode is coupled to one of the bit lines; and 
 the lower electrode is coupled to one of the diodes. 
   
     
     
         12 . The phase change memory device of  claim 1 , wherein:
 the phase change memory unit is one of a plurality of phase change memory units; and   the heat sink is one of a plurality of heat sinks disposed in a first direction between alternating pairs of the phase change memory units; and   each heat sink extends in a second direction that is substantially perpendicular to the first direction.   
     
     
         13 . A method of manufacturing a phase change memory device, the method comprising:
 forming a lower electrode on a substrate;   forming a heat sink adjacent to and spaced apart from the lower electrode;   forming a phase change material layer pattern on the lower electrode; and   forming an upper electrode on the phase change material layer pattern;   wherein forming the heat sink includes forming the heat sink having a top surface lower than a top surface of the upper electrode.   
     
     
         14 . The method of  claim 13 , further comprising
 forming a first insulation layer on the substrate to cover the lower electrode;   forming the heat sink on a portion of the first insulation layer;   forming a second insulation layer on the first insulation layer to cover the heat sink;   removing upper portions of the first and second insulation layers to expose the lower electrode;   removing an upper portion of the exposed lower electrode to form a recess; and   forming the phase change material layer pattern to fill the recess.   
     
     
         15 . The method of  claim 13 , wherein:
 forming the lower electrode includes forming a plurality of lower electrodes both in the first and second directions to form a lower electrode array;   forming the upper electrode includes forming a plurality of upper electrodes in the second direction, each upper electrode extending in the first direction; and   forming the heat sink includes forming a plurality of heat sinks between structures arranged in the first direction, each structure including a corresponding lower electrode and a corresponding phase change material layer pattern disposed in the second direction, and each heat sink extending in the second direction.   
     
     
         16 . The method of  claim 13 , further comprising:
 prior to forming the lower electrode, forming a plurality of word lines electrically connected to the plurality of lower electrodes, the word lines being formed in the first direction, and each word line extending in the second direction; and   after forming the upper electrode, forming bit lines electrically connected to the upper electrodes, respectively, each bit line extending in the first direction.   
     
     
         17 . The method of  claim 13 , wherein forming the heat sink includes:
 forming a first insulation layer on the substrate to cover the lower electrode;   forming a metal layer on the first insulation layer to sufficiently fill a space adjacent the lower electrode; and   removing an upper portion of the metal layer to form the heat sink filling a lower portion of the space.   
     
     
         18 . A phase change memory device, comprising:
 a phase change memory unit, including:
 a phase change material layer pattern; 
 a lower electrode beneath the phase change material layer pattern, the lower electrode configured to heat the phase change material layer pattern; and 
 an upper electrode on the phase change material layer pattern; 
   an insulating layer on the phase change memory unit; and   a heat sink configured to absorb heat from the phase change memory unit;   wherein the heat sink is disposed adjacent to an interface of the lower electrode and the phase change material layer pattern and disposed beneath at least a part of the insulating layer.   
     
     
         19 . The phase change memory device of  claim 18 , wherein:
 the heat sink includes a first extension portion extending in a first direction and a second extension portion extending in a second direction; and   the first direction is substantially perpendicular to the second direction.   
     
     
         20 . The phase change memory device of  claim 19 , wherein the first extension portion is spaced apart from the second extension portion.