Non-volatile memory device having bottom electrode

1. A non-volatile memory device comprising:

a bottom electrode disposed on a substrate and having a lower part and an upper part;

a conductive spacer disposed on a sidewall of the lower part of the bottom electrode;

a nitride spacer disposed on a top surface of the conductive spacer and a sidewall of the upper part of the bottom electrode; and

a resistance changeable element disposed on the upper part of the bottom electrode and the nitride spacer,

wherein the upper part of the bottom electrode contains nitrogen (N).

2. The device of claim 1 , wherein:

the conductive spacer is directly on the sidewall of the lower part of the bottom electrode; and

the nitride spacer is directly on the sidewall of the upper part of the bottom electrode.

3. The device of claim 1 , wherein the nitride spacer comprises a material obtained by nitrifying the conductive spacer and is self-aligned with the conductive spacer.

4. The device of claim 3 , wherein the conductive spacer comprises silicon (Si), and the nitride spacer comprises silicon nitride.

5. The device of claim 1 , wherein a top surface of the upper part of the bottom electrode is lower than a top surface of the nitride spacer relative to the substrate.

6. The device of claim 5 , wherein the resistance changeable element directly contacts the top surface of the upper part of the bottom electrode and a lateral surface of the nitride spacer.

7. The device of claim 1 , wherein a top surface of the nitride spacer is lower than a top surface of the upper part of the bottom electrode relative to the substrate.

8. The device of claim 1 , further comprising:

a metal silicide layer interposed between the lower part of the bottom electrode and the conductive spacer; and

a metal silicide nitride layer disposed on the metal silicide layer and interposed between the nitride spacer and the upper part of the bottom electrode.

9. The device of claim 1 , further comprising a core layer disposed under the resistance changeable element,

wherein the bottom electrode covers a sidewall and bottom surface of the core layer.

10. The device of claim 9 , further comprising a core nitride layer disposed on and self-aligned with the core layer,

wherein the core nitride layer covers the sidewall of the upper part of the bottom electrode.

11. The device of claim 1 , further comprising a lower insulating layer having a contact hole extending to the substrate,

wherein the bottom electrode, the conductive spacer, and the nitride spacer are confined within the contact hole.

12. The device of claim 1 , further comprising a diode disposed on the substrate,

wherein the bottom electrode and the conductive spacer are disposed on the diode.

13. The device of claim 12 , wherein the diode comprises:

a first diode pattern; and

a second diode pattern disposed on the first diode pattern,

wherein the conductive spacer directly contacts the second diode pattern, and the second diode pattern and the conductive spacer comprise semiconductor layers of the same conductivity type.

14. The device of claim 13 , wherein each of the second diode pattern and the conductive spacer comprises a P-type silicon layer.

15. The device of claim 13 , wherein the conductive spacer extends between the bottom electrode and the second diode pattern.

16. The device of claim 1 , wherein the upper and lower parts of the bottom electrode comprise the same material.

17. The device of claim 1 , wherein the lower part of the bottom electrode contains a smaller amount of nitrogen than the upper part of the bottom electrode.

18. A non-volatile memory device comprising:

a first diode pattern on a substrate;

a second diode pattern on the first diode pattern;

a bottom electrode on the second diode pattern;

a conductive spacer on the second diode pattern and configured to cover a first portion of a sidewall of the bottom electrode;

a nitride spacer on the conductive spacer and adjacent to a second portion of the sidewall of the bottom electrode;

a metal silicide layer interposed between the conductive spacer and the first portion of the sidewall of the bottom electrode;

a metal silicide nitride layer on the metal silicide layer and interposed between the nitride spacer and the second portion of the sidewall of the bottom electrode; and

a resistance changeable element on the bottom electrode, the metal silicide nitride layer, and the nitride spacer,

wherein the metal silicide layer contacts the second diode pattern.

19. A non-volatile memory device comprising:

a substrate;

a diode pattern on the substrate;

a bottom electrode on the diode pattern that extends upward away from the substrate, wherein an upper portion of the bottom electrode contains more nitrogen than a lower portion of the bottom electrode;

a conductive spacer that extends from the diode pattern upward covering a sidewall of the bottom electrode, wherein an upper portion of the conductive spacer is a nitride spacer containing more nitrogen than a lower portion of the conductive spacer; and

a resistance changeable element on the bottom electrode and the nitride spacer.

20. The non-volatile memory device of claim 19 , further comprising:

a metal silicide layer that extends from the diode pattern upward between the conductive spacer and the sidewall of the bottom electrode, wherein an upper portion of the metal silicide layer is a metal silicide nitride layer containing more nitrogen than a lower portion of the metal silicide layer.