Memory cell that includes a sidewall collar for pillar isolation and methods of forming the same

1. A method of forming a memory cell, the method comprising:

forming a steering element pillar having a first stiffness and a sidewall;

forming a sidewall collar along at least a portion of the sidewall of the steering element pillar, the sidewall collar having a second stiffness, wherein the second stiffness is greater than the first stiffness; and

forming a memory element coupled to the steering element pillar.

2. The method of claim 1 , wherein the steering element pillar comprises polycrystalline semiconductor material.

3. The method of claim 1 , wherein the steering element pillar comprises polysilicon.

4. The method of claim 1 , wherein the steering element pillar comprises a P-I-N, P-N, N-I-P or N-P diode.

5. The method of claim 1 , wherein the sidewall collar comprises dielectric material.

6. The method of claim 1 , wherein the dielectric material comprises one or more of silicon nitride, hafnium dioxide and silicon carbide.

7. A method of forming a memory array, the method comprising:

forming a plurality of steering element pillars each having a first stiffness and a sidewall;

forming a sidewall collar along at least a portion of the sidewall of each steering element pillar, each sidewall collar having a second stiffness, wherein the second stiffness is greater than the first stiffness; and

forming a plurality of memory elements each coupled to a different one of the steering element pillars.

8. The method of claim 7 , wherein each steering element pillar comprises a P-I-N, P-N, N-I-P or N-P diode.

9. The method of claim 7 , wherein each sidewall collar comprises dielectric material.

10. The method of claim 7 , wherein the dielectric material comprises one or more of silicon nitride, hafnium dioxide and silicon carbide.