Nanoshape patterning techniques that allow high-speed and low-cost fabrication of nanoshape structures

• US 10,026,609 B2
• Filed: 10/23/2015
• Issued: 07/17/2018
• Est. Priority Date: 10/23/2014
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Sreenivasan, Sidlgata V., Cherala, Anshuman, Chopra, Meghali, Bonnecaze, Roger, Abed, Ovadia, Yin, Bailey, Mallavarapu, Akhila, Singhal, Shrawan, Gawlik, Brian
• Primary Examiner(s): Everhart, Caridad
• Application Number:
  US14/921,866
• Publication Number:
  US 20160118249A1
• Time in Patent Office: 998 Days
• CPC Class Codes: B81C 1/00031 Regular or irregular arrays of nanoscale structures, e.g. etch mask layer photomechanical, e.g. photolithographic, production of textured or patterned surfaces G03F7/00; lithographic processes for making patterned surfaces using printing and stamping G03F7/0002
• CPC Class Codes: B81C 2201/0187 Controlled formation of micro- or nanostructures using a template positioned on a substrate
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G02B 6/1226 involving surface plasmon interaction
• CPC Class Codes: G03F 7/0002 Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
• CPC Class Codes: G11B 5/746 Bit Patterned record carriers, wherein each magnetic isolated data island corresponds to a bit
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02521 Materials
• CPC Class Codes: H01L 21/02617 Deposition types
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 29/945 Trench capacitors
• CPC Class Codes: Y10S 977/887 Nanoimprint lithography, i.e. nanostamp
• CPC Class Codes: Y10S 977/888 Shaping or removal of materials, e.g. etching
• CPC Class Codes: Y10S 977/89 Deposition of materials, e.g. coating, cvd, or ald

Abstract

A method for template fabrication of ultra-precise nanoscale shapes. Structures with a smooth shape (e.g., circular cross-section pillars) are formed on a substrate using electron beam lithography. The structures are subject to an atomic layer deposition of a dielectric interleaved with a deposition of a conductive film leading to nanoscale sharp shapes with features that exceed electron beam resolution capability of sub-10 nm resolution. A resist imprint of the nanoscale sharp shapes is performed using J-FIL. The nanoscale sharp shapes are etched into underlying functional films on the substrate forming a nansohaped template with nanoscale sharp shapes that include sharp corners and/or ultra-small gaps. In this manner, sharp shapes can be retained at the nanoscale level. Furthermore, in this manner, imprint based shape control for novel shapes beyond elementary nanoscale structures, such as dots and lines, can occur at the nanoscale level.

Claims

1. A method for template fabrication of ultra-precise nanoscale shapes, the method comprising:

forming structures with a smooth shape on a substrate using lithography;

subjecting said structures to an atomic layer deposition of one or more films leading to nanoscale sharp shapes with features that exceed lithography resolution capability of sub-10 nm resolution;

performing a resist imprint of said nanoscale sharp shapes using imprint lithography; and

etching said nanoscale sharp shapes into underlying functional films on said substrate forming a nanoshaped template with nanoscale sharp shapes that comprise one or more of the following;

sharp corners and ultra-small gaps ranging from 1 to 10 nanometers.

2. The method as recited in claim 1, wherein said structures comprise circular or elliptical cross-section pillars.

3. The method as recited in claim 1, wherein said substrate comprises a fused silica substrate.

4. The method as recited in claim 1, wherein said underlying functional films comprise thermal oxide.

5. The method as recited in claim 1, wherein said nanoscale sharp shapes are diamond-like shapes.

6. The method as recited in claim 1, wherein said nanoshaped template with nanoscale sharp shapes is utilized in magnetic memory, nanophotonic devices or biomedical applications.

7. The method as recited in claim 1, wherein said lithography comprises one of the following:

electron beam lithography, ion beam lithography and multiphoton lithography.

8. The method as recited in claim 1, wherein said one or more films comprises a dielectric interleaved with a deposition of a conductive film.

9. The method as recited in claim 1, wherein said imprint lithography comprises Jet and Flash Imprint Lithography (J-FIL).

10. The method as recited in claim 1, wherein said one or more films comprise two or more films comprising a dielectric and a conducting film.

11. The method as recited in claim 10, wherein said dielectric comprises one of the following:

silicon dioxide and silicon nitride, wherein said conducting film comprises titanium nitride.

12. The method as recited in claim 1, wherein said nanoshaped template is pre-compensated to account for pattern degradation of shape during said etching.

13. The method as recited in claim 12, wherein said nanoshaped template is pre-compensated by using a nanoscale bridge that connects adjacent nanoscale sharp shapes.

14. A method for template replication of ultra-precise nanoscale shapes, the method comprising:

using a master template for patterning of imprint material on a residual layer that is positioned on a dissolvable layer which is positioned on a substrate;

depositing a dielectric layer over said imprint material and said residual layer to capture shape details;

performing one of chemical vapor deposition, physical vapor deposition and atomic layer deposition of said deposited dielectric layer to create a film over said imprint material and said residual layer;

planarizing said film;

bonding a replica substrate onto said planarized film;

eliminating said dissolvable layer followed by flipping over a structure comprising said imprint material, said residual layer and said substrate; and

removing said imprint material thereby forming a replica template.

15. The method as recited in claim 14, wherein said dissolvable layer has a thickness between 1 and 20 micrometers.

16. The method as recited in claim 14, wherein said imprint material is removed using an oxidizing cleaning technique.

17. The method as recited in claim 14, wherein said dissolvable layer is eliminated in a liquid bath.

18. The method as recited in claim 17 further comprising:

drying said structure comprising said imprint material, said residual layer and said substrate after eliminating said dissolvable layer in said liquid bath.

19. A method to fabricate shaped cross-section silicon nanowires, the method comprising:

depositing a sacrificial polymeric layer on a silicon;

imprinting on said sacrificial polymeric layer using a nanoscale shaped template;

etching a polymeric residual layer resulting from said imprinting;

etching an underlying sacrificial polymeric layer following said etching of said polymeric residual layer, wherein said underlying sacrificial polymeric layer etch results in an undercut;

performing a physical vapor deposition of a metal;

removing said sacrificial polymeric layer to create nanoshaped metal structures on said silicon; and

performing a metal assisted chemical etching process to create nanowires.

20. The method as recited in claim 19, wherein said metal comprises one of the following:

gold, silver, platinum, rhodium, copper and palladium.

21. The method as recited in claim 19, wherein a cross-section of said nanoshaped metal structures allows for enhanced surface area of said silicon per unit projected area of said silicon.

22. The method as recited in claim 19 further comprising:

depositing a sacrificial inorganic layer between said sacrificial polymeric layer and said polymeric residual layer.

23. The method as recited in claim 22, wherein said sacrificial inorganic layer comprises one of the following:

silicon dioxide and silicon nitride.

24. The method as recited in claim 19, wherein said nanowires are harvested by casting said nanowires in a polymer and shearing said nanowires from a wafer.

25. The method as recited in claim 24, wherein said shearing of said nanowires is performed using mechanical or acoustic forces.

26. A method to fabricate shaped cross-section silicon nanowires, the method comprising:

depositing a sacrificial polymeric layer on a silicon;

imprinting on said sacrificial polymeric layer using a nanoscale shaped template;

coating said sacrificial polymeric layer with a silicon organic coating;

planarizing and etching said silicon organic coating in a plasma involving fluorine and oxygen;

etching an underlying sacrificial polymeric layer, wherein said underlying sacrificial polymeric layer etch results in an undercut;

performing a physical vapor deposition of a metal to promote adhesion;

performing a physical vapor deposition of a second metal;

removing said sacrificial polymeric layer to create nanoshaped metal structures on said silicon; and

performing a metal assisted chemical etching process to create nanowires.

27. The method as recited in claim 26, wherein said second metal comprises one of the following:

gold, silver, platinum, rhodium, copper and palladium.

28. The method as recited in claim 26, wherein a cross-section of said nanoshaped metal structures allows for enhanced surface area of said silicon per unit projected area of said silicon.

29. The method as recited in claim 26, wherein said nanowires are harvested by casting said nanowires in a polymer and shearing said nanowires from a wafer.

30. The method as recited in claim 29, wherein said shearing of said nanowires is performed using mechanical or acoustic forces.