PCRAM STRUCTURE

1 . A memory device comprising:

a substrate;

a bottom electrode disposed over the substrate;

an insulating layer disposed over the bottom electrode, the insulating layer having a through hole defined in the insulating layer;

a heater disposed in the through hole;

a phase change material layer disposed over the heater;

a selector layer disposed over the phase change material layer;

an intermediate layer over the through hole; and

a metal layer disposed over the selector layer.

2 . The memory device of claim 1 , wherein the intermediate layer is wider than a diameter of the through hole.

3 . The memory device of claim 1 , wherein the metal layer is wider than the phase change material layer.

4 . The memory device of claim 1 , wherein the phase change material layer is disposed in the through hole.

5 . The memory device of claim 1 , wherein the selector layer is disposed in the through hole.

6 . The memory device of claim 1 , wherein the intermediate layer contacting the metal layer.

7 . The memory device of claim 1 , wherein the intermediate layer is formed of at least one of carbon and tungsten.

8 . The memory device of claim 1 , wherein the metal layer functions as a top electrode.

9 . A memory device comprising:

a substrate;

a bottom electrode disposed over the substrate;

a first heater disposed over the bottom electrode;

a first phase change material layer disposed over the first heater;

a first selector layer disposed over the first phase change material layer;

an intermediate layer disposed over the first selector layer;

a metal layer disposed over the intermediate layer;

a second selector layer disposed over the metal layer;

a second heater and a second phase change material layer disposed over the second selector layer;

a top electrode disposed over the second heater and the second phase change material layer; and

an insulating layer between the bottom electrode and the top electrode, enclosing, with the bottom and top electrodes, the first and second heaters, the first and second selector layers, the first and second phase change material layers, and the metal layer.

10 . The memory device of claim 9 , wherein the intermediate layer extends wider than the first and second heaters.

11 . The memory device of claim 9 , wherein the metal layer is wider than the first phase change material layer.

12 . The memory device of claim 9 , wherein the second heater is disposed over the second phase change material layer.

13 . The memory device of claim 9 , wherein the second phase change material layer is disposed over the second heater.

14 . The memory device of claim 9 , wherein the intermediate layer is wider than the first and second heaters.

15 . The memory device of claim 9 , wherein the intermediate layer contacts the metal layer.

16 . The memory device of claim 9 , wherein the intermediate layer is formed of at least one of carbon and tungsten.

17 . A method of manufacturing a memory device, comprising:

forming a bottom electrode over a substrate;

forming an insulating layer over the bottom electrode;

forming a through hole in the insulating layer;

forming a heater in the through hole;

forming a phase change material layer over the heater;

forming a selector layer over the phase change material layer;

forming an intermediate layer over the selector layer; and

forming a metal layer over the intermediate layer.

18 . The method of manufacturing the memory device of claim 17 , wherein the intermediate layer contacts the metal layer.

19 . The method of manufacturing the memory device of claim 17 , wherein the phase change material layer is formed in the through hole.

20 . The method of manufacturing the memory device of claim 17 , wherein the intermediate layer is formed of at least at least one of carbon and tungsten.