Integrated circuit including spacer defined electrode

1. An integrated circuit comprising:

a contact;

a first spacer comprising a first sidewall and a second sidewall opposite the first sidewall;

a first electrode including a first portion and a second portion, the first portion contacting the first sidewall of the first spacer, the second portion contacting the contact and defined by the first spacer such that the second portion comprises a sidewall aligned with the second sidewall of the first-spacer;

a second electrode; and

resistivity changing material between the second electrode and the first portion of the first electrode.

2. The integrated circuit of claim 1 , wherein the first portion of the first electrode is sidewall defined and has a sublithographic cross-section.

3. The integrated circuit of claim 1 , wherein the resistivity changing material comprises a first portion having a sublithographic cross-section contacting the first portion of the first electrode.

4. The integrated circuit of claim 3 , wherein the first portion of the resistivity changing material is defined by second spacers.

5. The integrated circuit of claim 3 , wherein the first portion of the resistivity changing material is defined by a tapered trench.

6. The integrated circuit of claim 3 , wherein the first portion of the resistivity changing material is defined by a sacrificial spacer defined trench.

7. The integrated circuit of claim 1 , wherein the resistivity changing material comprises phase change material.

8. A system comprising:

a host; and

a memory device communicatively coupled to the host, the memory device comprising:

a first spacer comprising a first sidewall and a second sidewall opposite the first sidewall;

a first electrode including a first portion and a second portion, the first portion contacting the first sidewall of the first spacer, the second portion defined by the first spacer such that the second portion comprises a sidewall aligned with the second sidewall of the first spacer;

a second electrode; and

a phase change element between the first electrode and the second electrode.

9. The system of claim 8 , wherein the first portion of the first electrode is sidewall defined and has a sublithographic cross-section.

10. The system of claim 9 , wherein the phase change element comprises a first portion having a sublithographic cross-section contacting the first portion of the first electrode.

11. The system of claim 10 , wherein the memory device further comprises:

an access device coupled to the first electrode.

12. The system of claim 8 , wherein the memory device further comprises:

a write circuit configured to program the phase change element;

a sense circuit configured to read a state of the phase change element; and

a controller configured to control the write circuit and the sense circuit.

13. A memory comprising:

a first electrode consisting of a first portion and a second portion forming an L-shaped first electrode;

means for defining a size of the second portion of the first electrode;

a second electrode; and

means for confining current between the first electrode and the second electrode.

14. The memory of claim 13 , wherein the means for confining current is defined by spacers on sidewalk of a trench.

15. The memory of claim 13 , wherein the means for confining current is defined by a tapered trench.

16. The memory of claim 13 , wherein the means for confining current is defined by a sacrificial spacer defined trench.

17. The memory of claim 13 , wherein the means for confining current is defined by damascene patterning of resistivity changing material.

18. An integrated circuit comprising:

a memory array including rows and columns, the memory array comprising:

a plurality of first electrodes, each first electrode comprising a strip of electrode material formed by etching a line of electrode material along each row;

a plurality of lines of phase change material, each line of phase change material along a column and contacting at least two first electrodes along the column; and

a plurality of lines of electrode material, each line of electrode material along a column and contacting the line of phase change material along the column.

19. An integrated circuit comprising:

a contact;

a first spacer;

a first electrode consisting of a first portion and a second portion forming an L-shaped first electrode, the second portion contacting the contact and defined by the first spacer;

a second electrode; and

resistivity changing material between the second electrode and the first portion of the first electrode.

20. The integrated circuit of claim 19 , wherein the first portion of the first electrode is sidewall defined and has a sublithographic cross-section.

21. The integrated circuit of claim 19 , wherein the resistivity changing material comprises a first portion having a sublithographic cross-section contacting the first portion of the first electrode.

22. The integrated circuit of claim 21 , wherein the first portion of the resistivity changing material is defined by second spacers.

23. The integrated circuit of claim 21 , wherein the first portion of the resistivity changing material is defined by a tapered trench.

24. The integrated circuit of claim 21 , wherein the first portion of the resistivity changing material is defined by a sacrificial spacer defined trench.

25. The integrated circuit of claim 19 , wherein the resistivity changing material comprises phase change material.

26. A system comprising:

a host; and

a memory device communicatively coupled to the host, the memory device comprising:

a first spacer;

a first electrode consisting of a first portion and a second portion forming an L-shaped

first electrode, the second portion defined by the first spacer;

a second electrode; and

a phase change element between the first electrode and the second electrode.

27. The system of claim 26 , wherein the first portion of the first electrode is sidewall defined and has a sublithographic cross-section.