Phase change memory device

1. A phase change material memory device, comprising:

one or more electrical contacts in a substrate;

a dielectric cover layer on the electrical contacts and substrate;

a lower conductive shell trench above one of the one or more electrical contacts;

an upper conductive shell inside the trench on the lower conductive shell, wherein be lower conductive shell keeps the upper conductive shell apart from the dielectric cover layer in a horizontal direction with respect to an upper surface of the substrate;

a conductive plug filling the upper conductive shell;

a liner layer on the dielectric cover layer and covering the conductive plug; and

a phase change material block over the liner layer and the conductive plug, and in the trench.

2. The phase change material memory device of claim 1 , wherein the trench has a width in a range of about 25 nanometers (nm) to about 100 nm.

3. The phase change material memory device of claim 1 , wherein the phase change material block is germanium-antimony-tellurium (GeSbTe).

4. The phase change material memory device of claim 1 , wherein the lower conductive shell is a metal compound having a resistivity of about 45 kOhm/sq at 5 nm thickness.

5. The phase change material memory device of claim 1 , further comprising a protective slab on the phase change material block.

6. The phase change material memory device of claim 5 , further comprising a top conductive contact on the protective slab.

7. The phase change material memory device of claim 6 , wherein the conductive plug is a metal compound having a resistivity of about 45 kOhm/sq at 5 nm thickness.