Phase-change memory device and method of fabricating the same

1. A phase-change memory device, comprising:

a semiconductor substrate having a phase-change area of a hole type;

a first material-rich first phase-change layer formed only on sidewalls and bottom of the phase-change area and including a hetero compound of the first material and a second material; and

a second phase-change layer formed on a surface of the first phase-change layer to fill the phase-change area.

2. The phase-change memory device according to claim 1 , wherein the first material is antimony (Sb) and the second material is tellurium (Te).

3. The phase-change memory device according to claim 1 , wherein the first material is germanium (Ge) and the second material is tellurium (Te).

4. The phase-change memory layer according to claim 1 , wherein the first material is silicon (Si) and the second material is antimony (Sb).

5. The phase-change memory device of claim 1 , wherein the second phase-change layer is formed of a ternary compound including third to fifth materials.

6. The phase-change memory device of claim 5 , wherein the second phase-change layer is a chalcogenide (GST) layer comprised of germanium (Ge), antimony (Sb) and tellurium (Te).

7. The phase-change memory device of claim 1 , further comprising a lower electrode electrically connected to the first phase-change layer on the semiconductor substrate.

8. The phase-change memory device of claim 1 , wherein at least one of the first and second phase-change layers includes a dopant.