Methods for forming carbon nanotubes

• US 8,545,936 B2
• Filed: 03/28/2008
• Issued: 10/01/2013
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Huotari, Hannu A., Haukka, Suvi P.
• Primary Examiner(s): CHEN, BRET P
• Application Number:
  US12/058,565
• Publication Number:
  US 20090246367A1
• Time in Patent Office: 2,013 Days
• Field of Search: 427/301, 427/314, 427/250, 427/249.1, 117/84
• US Class Current: 427/215
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 32/162 characterised by catalysts
• CPC Class Codes: C30B 25/00 Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
• CPC Class Codes: C30B 29/02 Elements
• CPC Class Codes: C30B 29/602 Nanotubes

Abstract

Methods of forming a roughened metal surface on a substrate for nucleating carbon nanotube growth, and subsequently growing carbon nanotubes are provided. In preferred embodiments roughened surfaces are formed by selectively depositing metal or metal oxide on a substrate surface to form discrete, three-dimensional islands. Selective deposition may be obtained, for example, by modifying process conditions to cause metal agglomeration or by treating the substrate surface to provide a limited number of discontinuous reactive sites. The roughened metal surface may then be used as nucleation points for initiating carbon nanotube growth. The carbon nanotubes are grown in the same process chamber (in-situ) as the formation of the three dimensional metal islands without exposing the substrate to air.

Claims

1. A method for growing carbon nanotubes on a substrate in a reaction space, comprising:

forming an initial surface termination on a surface of the substrate;

forming discontinuous metal particles at distinct sites on the surface by atomic layer deposition; and

depositing carbon nanotubes on to said metal particles in-situ.

2. The method of claim 1, wherein depositing said carbon nanotubes comprises contacting the substrate with CO.

3. The method of claim 1, wherein said metal particles comprise metal oxide.

4. The method of claim 1, wherein the temperature of the substrate is about the same when depositing said carbon nanotubes and forming said metal particles.

5. The method of claim 1, wherein the substrate is at a temperature less than about 650°

C. when depositing said carbon nanotubes.

6. The method of claim 1, wherein depositing is carried out at a substrate temperature of about 440°

C. to about 650°

C.

7. The method of claim 1, wherein said reaction space is part of an ALD, CVD, Epitaxial, or furnace reactor.

8. The method of claim 1, wherein the initial surface termination is formed on a surface comprising silicon.

9. The method of claim 1, wherein evenly distributed carbon nanotube networks are deposited on said metal particles.

10. The method of claim 1, wherein depositing said carbon nanotubes comprises depositing a carbon nanotube network in an ordered manner.

11. The method of claim 1, wherein the direction of growth of said carbon nanotubes is controlled by controlling the size and density of said metal particles.

12. The method of claim 1, wherein forming an initial surface termination comprises heating the substrate to a temperature above about 200°

C.

13. The method of claim 12, wherein forming an initial surface termination further comprises treating said substrate with a halide chemical.

14. The method of claim 1, wherein forming an initial surface termination comprises heating the substrate to a temperature above about 400°

C.

15. The method of claim 1, wherein forming an initial surface termination comprises treating said substrate with a halide chemical.

16. The method of claim 1, wherein forming said metal particles on the surface by atomic layer deposition comprises alternately and sequentially providing a noble metal precursor and oxygen precursor.

17. A method for growing carbon nanotubes, comprising:

providing a substrate in a reaction space;

modifying the surface of the substrate to produce discrete reactive sites;

depositing metal particles at the reactive sites using alternating and sequential pulses of a first metal source chemical and a second non-metal species; and

subsequently depositing carbon nanotubes on to said metal particles, wherein the substrate is not exposed to air between depositing metal particles and depositing carbon nanotubes.

18. The method of claim 17, wherein said metal particles comprise metal oxide.

19. The method of claim 17, wherein depositing said metal particles and depositing said carbon nanotubes are performed in the same reaction chamber.

20. The method of claim 17, wherein depositing said metal particles and depositing said carbon nanotubes are performed in the same cluster tool.

21. The method of claim 17, wherein modifying said surface of said substrate, depositing said metal particles, and depositing said carbon nanotubes are performed at approximately the same temperature.

22. The method of claim 17, wherein deposition of said carbon nanotubes is performed at about 440°

C. to about 650°

C.

23. The method of claim 17, wherein the modified surface comprises silicon.

24. The method of claim 17, wherein modifying the surface comprises heating the substrate to a temperature above about 200°

C.

25. The method of claim 17, wherein modifying the surface comprises treating said substrate with a halide chemical.

26. The method of claim 17, wherein depositing said metal particles on the surface comprises alternately and sequentially providing a noble metal precursor and oxygen precursor.

27. The method of claim 17, further comprising depositing a layer of material on the substrate after depositing said carbon nanotubes.

28. A method for forming carbon nanotubes on a substrate in a reaction space, comprising:

depositing catalyst nanoparticles on said substrate; and

depositing carbon nanotubes on said substrate in-situ.

29. The method of claim 28, further comprising depositing a film on the substrate in the same reaction space prior to depositing catalyst nanoparticles.

30. The method of claim 28, wherein the catalyst nanoparticles are deposited by alternately and sequentially providing a noble metal precursor and oxygen precursor.

31. The method of claim 28, wherein the carbon nanotubes are deposited by contacting the substrate with CO.

32. The method of claim 29, further comprising performing a chemical treatment after depositing said film on said substrate and before depositing said catalyst nanoparticles.

33. The method of claim 32, wherein performing said chemical treatment comprises providing a halide chemical.

34. The method of claim 29, further comprising a heat treatment after depositing said film and before depositing said catalyst nanoparticles.

35. The method of claim 34, wherein performing said heat treatment comprises heating the substrate to a temperature above about 200°

C.