Memory cell that employs a selectively fabricated carbon nano-tube reversible resistance-switching element and methods of forming the same
View Patent ↗In some aspects, a method of fabricating a memory cell is provided that includes fabricating a steering element above a substrate, and fabricating a reversible-resistance switching element coupled to the steering element by selectively fabricating carbon nano-tube (“CNT”) material above the substrate, wherein the CNT material comprises a single CNT. Numerous other aspects are provided.
1. A method of fabricating a memory cell comprising:
fabricating a steering element in the form of a pillar structure above a substrate; and
fabricating a reversible-resistance switching element coupled to the steering element by selectively fabricating carbon nano-tube (“CNT”) material above the substrate, wherein:
the CNT material comprises a single CNT that includes both the steering element and the reversible resistance-switching element, and the pillar structure has a width of less than about 10 nanometers.
2. The method of claim 1 , wherein fabricating the reversible-resistance switching element includes:
fabricating a CNT seeding layer;
patterning and etching the CNT seeding layer; and
selectively fabricating a single CNT on the CNT seeding layer.
3. The method of claim 2 , wherein fabricating the CNT seeding layer includes:
depositing titanium nitride; and
roughening a surface of the deposited titanium nitride.
4. The method of claim 3 , further comprising selectively depositing a metal layer on the roughened titanium nitride surface.
5. The method of claim 4 , wherein the metal layer comprises nickel, cobalt or iron.
6. The method of claim 2 , wherein fabricating the CNT seeding layer includes:
depositing titanium nitride above the first conductor; and
selectively depositing a metal catalyst layer on the titanium nitride.
7. The method of claim 6 , wherein the metal layer comprises nickel, cobalt or iron.
8. The method of claim 2 , wherein the CNT seeding layer comprises nickel, cobalt or iron.
9. The method of claim 1 wherein fabricating the reversible-resistance switching element includes:
fabricating a CNT seed particle; and
selectively fabricating a single CNT on the CNT seeding particle.
10. The method of claim 9 , wherein the CNT seed particle comprises one or more of cobalt, titanium, iron, molybdenum, nickel, and an organo-metallic precursor derived from cobalt, titanium, iron, molybdenum or nickel.
11. The method of claim 1 , wherein fabricating the steering element comprises fabricating a p-n or p-i-n diode.
12. The method of claim 11 , wherein fabricating the steering element comprises fabricating a CNT diode.
13. The method of claim 1 , further comprising fabricating the reversible-resistance switching element above the steering element.
14. The method of claim 1 , further comprising fabricating the steering element above the reversible-resistance switching element.
15. A memory cell formed using the method of claim 1 .
16. A memory cell comprising:
a steering element in the form of a pillar structure having a width of less than about 10 nanometers; and
a reversible resistance-switching element coupled to the steering element, wherein the reversible resistance-switching element comprises a selectively fabricated carbon nano-tube (“CNT”) material, wherein the CNT material comprises a single CNT that includes both the steering element and the reversible resistance-switching element.
17. The memory cell of claim 16 , wherein the steering element comprises a p-n or p-i-n diode.
18. The memory cell of claim 17 , wherein the diode comprises a CNT diode.
19. The memory cell of claim 16 , further comprising a patterned and etched CNT seeding layer on which the CNT material is selectively fabricated.
20. The memory cell of claim 19 , wherein the CNT seeding layer comprises one or more of titanium nitride, tantalum nitride, nickel, cobalt and iron.
21. The memory cell of claim 16 , wherein the reversible-resistance switching element is above the steering element.
22. The memory cell of claim 16 , wherein the steering element is above the reversible-resistance switching element.
23. A monolithic three dimensional memory array comprising:
a first memory level formed above a substrate, the first memory level comprising:
a plurality of memory cells, wherein each memory cell of the first memory level comprises:
a steering element in the form of a pillar structure having a width of less than about 10 nanometers; and
a reversible resistance-switching element coupled to the steering element, wherein the reversible resistance-switching element comprises a selectively fabricated carbon nano-tube (“CNT”) material, wherein the CNT material comprises a single CNT that includes both the steering element and the reversible resistance-switching element; and
at least a second memory level monolithically formed above the first memory level.
24. The monolithic three dimensional memory array of claim 23 , wherein the steering element comprises a p-n or p-i-n diode.
25. The monolithic three dimensional memory array of claim 24 , wherein the diode comprises a CNT diode.
26. The monolithic three dimensional memory array of claim 23 , further comprising a patterned and etched CNT seeding layer on which the CNT material is selectively fabricated.
27. The monolithic three dimensional memory array of claim 26 , wherein the CNT seeding layer comprises one or more of titanium nitride, tantalum nitride, nickel, cobalt and iron.
28. The monolithic three dimensional memory array of claim 23 , wherein in each memory cell of the first memory level, the reversible-resistance switching element is above the steering element.
29. The monolithic three dimensional memory array of claim 23 , wherein in each memory cell of the first memory level, the steering element is above the reversible-resistance switching element.