Method for making nanostructured surfaces

• US 8,460,568 B2
• Filed: 12/29/2009
• Issued: 06/11/2013
• Est. Priority Date: 12/30/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: David, Moses M., Yu, Ta-Hua
• Primary Examiner(s): CULBERT, ROBERTS P
• Application Number:
  US13/142,441
• Publication Number:
  US 20120012557A1
• Time in Patent Office: 1,260 Days
• Field of Search: 216/67, 216/71
• US Class Current: 216/67
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A continuous method for making a nanostructured surface comprises (a) placing a substrate comprising a nanoscale mask on a cylindrical electrode in a vacuum vessel, (b) introducing etchant gas to the vessel at a predetermined pressure, (c) generating plasma between the cylindrical electrode and a counter-electrode, (d) rotating the cylindrical electrode to translate the substrate, and (e) anisotropically etching a surface of the substrate to provide anisotropic nanoscale features on the surface.

Claims

1. A continuous method for making a nanostructured surface comprising:

(a) placing a substrate comprising a nanoscale mask on a cylindrical electrode in a vacuum vessel,

(b) introducing etchant gas to the vessel at a predetermined pressure,

(c) generating plasma between the cylindrical electrode and a counter-electrode,

(d) rotating the cylindrical electrode to translate the substrate, and

(e) anisotropically etching a surface of the substrate to provide anisotropic nanoscale features on the surface.

2. The method of claim 1 wherein the plasma is generated using radio-frequency power.

3. The method of claim 2 wherein the power density of the radio-frequency power is between about 0.1 and about 1.0 watts/cm³.

4. The method of claim 3 wherein the power density of the radio-frequency power is between about 0.2 and about 0.3 watts/cm³.

5. The method of claim 1 wherein the gas comprises fluorine containing gas.

6. The method of claim 5 wherein the gas comprises perfluoroethane.

7. The method of claim 1 wherein the substrate comprises a flexible web.

8. The method of claim 7 wherein the flexible web comprises a polymer.

10. The method of claim 1 wherein the nanoscale mask comprises nanoparticles, nanotubes, or nanofibers dispersed within the substrate.

11. The method of claim 1 wherein the nanoscale mask comprises nanoparticle, nanotubes, or nanofibers oriented on the surface of the substrate.

12. The method of claim 10 or claim 11 wherein the nanoscale mask comprises nanoparticles.

13. The method of claim 12 wherein the nanoparticles comprise SiO₂, ZrO₂, TiO₂, ZnO, indium tin oxide, antimony tin oxide, poly(tetrafluoroethylene), or carbon.

14. The method of claim 12 wherein the nanoparticles are surface modified.

15. The method of claim 1 wherein the predetermined pressure is between about 1 mTorr and about 20 mTorr.

16. The method of claim 1 wherein the counter-electrode comprises the vacuum vessel.

17. The method of claim 1 wherein the anisotropic nanoscale features have a height to width ratio of about 5:

1 or greater.

18. The method of claim 1 wherein the anisotropic nanoscale features comprise nano-pillars.

19. The method of claim 1 wherein the substrate is etched to a depth of at least about 100 nm.

9. The method of 1 wherein the substrate comprises a microstructured surface.

20. A continuous method for making a nanostructured surface comprising:

(a) placing a substrate comprising a nanoscale dispersed phase on a cylindrical electrode in a vacuum vessel,

(b) introducing etchant gas to the vessel at a predetermined pressure,

(c) generating plasma between the cylindrical electrode and a counter-electrode,

(d) rotating the cylindrical electrode to translate the substrate, and

(e) anisotropically etching the dispersed phase to provide anisotropic nanoscale features on the surface.