Anisotropic nanotube fabric layers and films and methods of forming same

• US 8,128,993 B2
• Filed: 07/31/2009
• Issued: 03/06/2012
• Est. Priority Date: 07/31/2009
• Status: Active Grant

• Current Assignee: ZEON Corporation
• Original Assignee: Nantero Incorporated
• Inventors: Rueckes, Thomas, Sivarajan, Ramesh, Sen, Rahul
• Primary Examiner(s): Cleveland, Michael
• Assistant Examiner(s): ZHAO, XIAO SI
• Application Number:
  US12/533,695
• Publication Number:
  US 20110027497A1
• Time in Patent Office: 949 Days
• Field of Search: 427/207.1, 427/256, 428/206, 428/446, 428/450, 438/99, 438/677, 438/689, 438/700, 216/17, 216/18, 216/39
• US Class Current: 427/256
• CPC Class Codes: B05D 1/202 Langmuir Blodgett films (LB films)
• 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 32/158 Carbon nanotubes
• CPC Class Codes: H05K 2201/026 Nanotubes or nanowires
• CPC Class Codes: H05K 2201/0323 Carbon
• CPC Class Codes: H05K 2203/1173 Differences in wettability, e.g. hydrophilic or hydrophobic areas
• CPC Class Codes: H05K 3/048 using a lift-off resist pattern or a release layer pattern
• CPC Class Codes: H05K 3/1208 Pretreatment of the circuit board, e.g. modifying wetting properties; Patterning by using affinity patterns providing shape patterns H05K3/1258; adhesion treatments H05K3/38
• CPC Class Codes: H10K 30/821 comprising carbon nanotubes
• CPC Class Codes: H10K 71/611 using printing deposition, e.g. ink jet printing

Abstract

Methods for forming anisotropic nanotube fabrics are disclosed. In one aspect, a nanotube application solution is rendered into a nematic state prior to its application over a substrate. In another aspect, a pump and narrow nozzle assembly are employed to realize a flow induced alignment of a plurality of individual nanotube elements as they are deposited onto a substrate element. In another aspect, nanotube adhesion promoter materials are used to form a patterned nanotube application layer, providing narrow channels over which nanotube elements will self align during an application process. Specific dip coating processes which are well suited for aiding in the creation of anisotropic nanotube fabrics are also disclosed.

Claims

1. A method of forming an anisotropic nanotube fabric layer over a substrate element, which comprises:

forming a layer of a nanotube adhesion averter material over said substrate element;

depositing a photoresist mask over said layer of nanotube adhesion averter material such that at least one region of said layer of nanotube adhesion averter material is covered by said photoresist mask and at least one region of said layer of nanotube adhesion averter material is not covered by said photoresist mask;

etching away the at least one region of said layer of nanotube adhesion averter material not covered by said photoresist mask to form at least one gap within said layer of nanotube adhesion averter material;

backfilling said at least one gap within said layer of nanotube adhesion averter material with a nanotube adhesion promoter material to foam at least one nanotube adhesion structure;

stripping away said photoresist mask to leave a patterned application surface comprising the remaining nanotube adhesion averter material and the at least one nanotube adhesion structure;

depositing a layer of nanotube elements over said patterned application surface; and

washing said layer of nanotube elements such that substantially all nanotube elements not in physical contact with said at least one nanotube adhesion structure are removed.

2. The method of claim 1 wherein said layer of nanotube adhesion averter material is a self assembled monolayer.

3. The method of claim 1 wherein said layer of nanotube adhesion averter material is comprised of bis(trimethoxy silyl methyl)benzene.

4. The method of claim 1 wherein said photoresist mask is deposited in a predetermined pattern over said layer of nanotube adhesion averter material.

5. The method of claim 1 wherein the step of etching is performed via a reactive plasma etch process.

6. The method of claim 1 wherein said nanotube adhesion promoter material is aminopropyltriethoxysilane.

7. The method of claim 1 wherein said nanotube adhesion structures are narrow with respect to said substrate element.

8. The method of claim 7 wherein said nanotube adhesion structures range in width from about 1 nm to about 10 nm.

9. The method of claim 1 wherein said patterned application surface is substantially planar.

10. The method of claim 1 wherein said layer of nanotube elements is applied via a dip coating process.

11. The method of claim 10 wherein said dip coating process uses an air-liquid interface.

12. The method of claim 10 wherein said dip coating process uses a liquid-liquid interface.

13. The method of claim 10 wherein said dip coating process uses a nanotube application solution comprising nanotube elements.

14. The method of claim 13 wherein the concentration of the nanotube elements in said nanotube application solution is optimized to promote the formation of an anisotropic nanotube fabric layer over said at least one nanotube adhesion structure.

15. The method of claim 13 wherein said nanotube application solution is rendered into a nematic state to promote the formation of an anisotropic nanotube fabric layer over said at least one nanotube adhesion structure.

16. The method of claim 13, wherein the nematic state comprises a concentration of the nanotube elements in said nanotube application solution greater than 0.05 g/ml.

17. The method of claim 10 wherein the speed of the dip coating process is optimized to form an anisotropic nanotube fabric layer over said at least one nanotube adhesion structure.

18. The method of claim 17, wherein the speed of the dip coating process is in the range of about 5.4 microns/second to about 54 microns/second.

19. The method of claim 10 wherein the ambient temperature during the dip coating process is optimized to form an anisotropic nanotube fabric layer over said at least one nanotube adhesion structure.

20. The method of claim 19 wherein the ambient temperature comprises room temperature.

21. The method of claim 1 wherein said layer of nanotube elements is applied via a spin coating process.

22. The method of claim 1 wherein said layer of nanotube elements is applied via a spray coating process.

23. The method of claim 1 wherein the substrate element is selected from the group consisting of a silicon wafer, semiconductors, plastic, glass, a flexible polymer, a flexible substrate, and a transparent substrate.

24. The method of claim 1, wherein the thickness of the nanotube fabric layer comprises about 50 nm to about 200 nm.