Phase-change memory element

1. A phase-change memory element, comprising:

a composite layer comprising a plurality of alternating layers of dielectric material and low thermal conductivity material;

a via hole within the composite layer; and

a phase-change material filled into the via hole and having a vertical side contacting each layer of the alternating layers.

2. The phase-change memory element as claimed in claim 1 , wherein the low thermal conductivity material has a thermal conductivity of 0.1 W/m-K to 1 W/m-K.

3. The phase-change memory element as claimed in claim 1 , wherein the dielectric material comprises silicon oxide, silicon nitride, or combinations thereof.

4. The phase-change memory element as claimed in claim 1 , wherein the low thermal conductivity material comprises phase-change material.

5. The phase-change memory element as claimed in claim 1 , wherein the low thermal conductivity material comprises nitrogen-doped phase-change material.

6. The phase-change memory element as claimed in claim 1 , wherein the low thermal conductivity material comprises oxygen-doped phase-change material.

7. The phase-change memory element as claimed in claim 1 , wherein the thickness of the layers of the dielectric material is at least 3 nm.

8. The phase-change memory element as claimed in claim 1 , wherein the thickness of the low thermal conductivity material is at least 3 nm.

9. The phase-change memory element as claimed in claim 1 , wherein there is at least one layer of all the dielectric material and the low thermal conductivity material.

10. A phase-change memory element, comprising:

a composite layer comprising alternating concentric annular layers of dielectric material and low thermal conductivity material;

a via hole within the composite layer; and

a phase-change material occupying at least one portion of the via hole,

wherein the alternating concentric annular layers surround the phase-change material.

11. The phase-change memory element as claimed in claim 10 , wherein the dielectric material directly contacts and surrounds the phase-change material.

12. A phase-change memory element, comprising:

at least one composite layer comprising a mixture of a dielectric material and a low thermal conductivity material;

a via hole within the composite layer; and

a phase-change material filling into the via hole.

13. The phase-change memory element as claimed in claim 12 , wherein the weight ratio of the composite layer between the dielectric material and the low thermal conductivity material is 1:10˜1:1.

14. The phase-change memory element as claimed in claim 12 , wherein the low thermal conductivity material has a thermal conductivity of 0.1 W/m-K to 1 W/m-K.

15. The phase-change memory element as claimed in claim 12 , wherein the dielectric material comprises silicon oxide, silicon nitride, or combinations thereof.

16. The phase-change memory element as claimed in claim 12 , wherein the low thermal conductivity material comprises phase-change material.

17. The phase-change memory element as claimed in claim 12 , wherein the low thermal conductivity material comprises nitrogen-doped phase-change material.

18. The phase-change memory element as claimed in claim 12 , wherein the low thermal conductivity material comprises oxygen-doped phase-change material.

19. The phase-change memory element as claimed in claim 12 , wherein the thickness of the composite layer is at least 3 nm.

20. The phase-change memory element as claimed in claim 12 , wherein at least one layer is entirely the low thermal conductivity material.

21. The phase-change memory element as claimed in claim 12 , wherein the composite layer is a horizontal composite layer.