PHASE CHANGE MEMORY DEVICES AND METHODS OF MANUFACTURING THE SAME

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.