Systems and methods for rapidly fabricating nanopatterns in a parallel fashion over large areas

• US 10,207,469 B2
• Filed: 12/08/2015
• Issued: 02/19/2019
• Est. Priority Date: 12/08/2014
• Status: Active Grant

• Current Assignee: University of Houston System
• Original Assignee: University of Houston System
• Inventors: Donnelly, Vincent M., Economou, Demetre J., Tian, Siyuan
• Primary Examiner(s): Vinh, Lan
• Application Number:
  US15/534,312
• Publication Number:
  US 20170361551A1
• Time in Patent Office: 1,169 Days
• Field of Search: 438706, 438719723, 438736, 438769, 438770, 216 26, 216 41, 216 47
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29D 11/00365 Production of microlenses lenticular sheets B29D11/00278
• CPC Class Codes: B29D 11/00375 by moulding lenses in holes through a substrate
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G03F 1/20 Masks or mask blanks for imaging by charged particle beam [CPB] radiation, e.g. by electron beam; Preparation thereof
• CPC Class Codes: H01J 2237/21 Focus adjustment lenses H01J2237/10
• CPC Class Codes: H01J 2237/2811 Large objects
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 2237/31776 Shaped beam
• CPC Class Codes: H01J 37/3026 Patterning strategy
• CPC Class Codes: H01J 37/3174 Particle-beam lithography, e.g. electron beam lithography
• CPC Class Codes: H01L 21/0274 Photolithographic processes

Abstract

Nanopantography is a method for patterning nanofeatures over large areas. Transfer of patterns defined by nanopantography using highly selective plasma etching, with an oxide layer of silicon serving as a hard mask, can improve patterning speed and etch profile. With this method, high aspect ratio features can be fabricated in a substrate with no mask undercut. The ability to fabricate complex patterns using nanopantography, followed by highly selective plasma etching, provides improved patterning speed, feature aspect ratio, and etching profile.

Claims

1. A method for creating an array of substantially uniform features in a substrate, the method comprising the steps of:

processing a substrate to provide a plurality of electrostatic lenses,

wherein the substrate comprises a bottom layer of semiconductive material, a lens layer above the bottom layer, and an electrode layer above the lens layer, and

each of the plurality of electrostatic lenses comprises an opening in the electrode layer and the lens layer;

performing nanopantography on the substrate for a first predetermined amount of time to generating a masking layer with a pattern on the bottom layer, wherein the nanopantography generates the masking layer by utilizing the electrostatic lenses to generate the pattern with an ion beam; and

performing a second etching on the substrate to transfer the pattern in the masking layer produced by the nanopantography step to the bottom layer to form an array of nanofeatures.

2. The method of claim 1, wherein the masking layer is a native oxide of the bottom layer.

3. The method of claim 1, wherein the substrate is tilted off a normal axis with respect to an ion beam axis to form the pattern in the masking layer.

4. The method of claim 1, wherein a processing time for the nanopantography step is equal to or less than 3 minutes.

5. The method of claim 1, wherein a resolution of at least one nanofeature from the array of nanofeatures is 15 nm full width at half maximum (FWHM) or less.

6. The method of claim 1, wherein ion energies during the plasma etching step are below the ion-assisted etching threshold for the masking layer.

7. The method of claim 1, wherein an aspect ratio of at least one nanofeature from the array of nanofeatures is 6 or greater.

8. The method of claim 1, wherein at least one nanofeature from the array of nanofeatures has top dimensions equal to or less than 10 nm.

9. The method of claim 1, wherein the step of performing nanopantography etches the pattern into the masking layer.

10. The method of claim 1, wherein the step of performing nanopantography causes a material to grow in the pattern defined by the masking layer.

11. The method of claim 1, wherein the second etching is a highly selective plasma etching.

12. The method of claim 11, wherein the second etching is a chlorine plasma etching.

13. The method of claim 11, wherein second etching is achieved under photo assisted etching conditions with ion energies below the ion-assisted etching threshold of the masking layer.

14. The method of claim 1, wherein the masking layer is a material that is deposited by the step of performing nanopantography.

15. The method of claim 14, wherein the masking layer is formed by a reaction with the bottom layer.

16. The method of claim 15, wherein the reaction is oxidation of the bottom layer.

17. A substrate with an array of nanofeatures, the substrate comprising:

a bottom layer of semiconductive material;

a masking layer on top of the bottom layer;

a lens layer on top of the masking layer;

an electrode layer above the lens layer;

a plurality of lens openings in the electrode layer and the lens layer, wherein each of the plurality of lens openings is a nanoscale sized opening, and each of the plurality of lens openings allow an ion beam to be focused when a voltage is applied across the electrode layer and the bottom layer; and

an array of nanofeatures in the masking layer and the bottom layer, wherein each of the array of nanofeatures comprises

an opening in a first region in the masking layer patterned using nanopantography, wherein the nanopantography writes a pattern in the masking layer by utilizing the electrostatic lenses to focus and write the pattern with an ion beam, and

a second region in the bottom layer formed by a second etching that transfers a pattern of the masking layer produced by the nanopantography step into the bottom layer.

18. The substrate of claim 17, wherein the masking layer is a native oxide layer of the bottom layer.

19. The substrate of claim 17, wherein aspect ratio of at least one nanofeature from the array of nanofeatures is 6 or greater.

20. The substrate of claim 17, wherein a resolution of at least one nanofeature from the array of nanofeatures is 15 nm full width at half maximum (FWHM) or less.

21. The substrate of claim 20, wherein each nanofeature in the array of nanofeatures are not undercut.

22. The substrate of claim 20, wherein each nanofeature in the array of nanofeatures do not taper.

23. The substrate of claim 20, wherein the array of nanofeatures are filled with material deposited by nanopantography in a self-aligned manner.