Silicon carbide nanoneedles and fabrication thereof

Patent metadata

Field	Value
Publication number	US-12246155-B2
Application number	US-202016987121-A
Country	US
Kind code	B2
Filing date	Aug 6, 2020
Priority date	Aug 6, 2020
Publication date	Mar 11, 2025
Grant date	Mar 11, 2025

Abstract

A product includes an elongated carbon-containing pillar having a bottom and a tip opposite the bottom. The width of the pillar measured 1 nm below the tip is less than 700 nm. A method includes masking a carbon-containing single crystal for defining masked regions and unmasked regions on the single crystal. The method also includes performing a plasma etch for removing portions of the unmasked regions of the single crystal, thereby defining a pillar in each unmasked region, and performing a chemical etch on the pillars at a temperature between 1200° C. and 1600° C. for selectively reducing a width of each pillar.

First claim

What is claimed is:

1. A product, comprising:
an elongated carbon-containing pillar having a bottom and a tip opposite the bottom,
wherein the width of the pillar measured 1 nm below the tip is less than 700 nm,
wherein the pillar, when formed, has no oxidation on an outer surface thereof.

2. The product as recited in claim 1 , wherein the tip is rounded.

3. The product as recited in claim 1 , wherein the pillar extends from a single crystal substrate having a bulk composition that is the same as the bulk composition of the pillar.

4. The product as recited in claim 3 , wherein the pillar has no higher concentration of defects per unit volume than the single crystal substrate.

5. The product as recited in claim 1 , wherein the pillar has a faceted peripheral outer surface.

6. The product as recited in claim 1 , wherein the pillar has a rounded peripheral outer surface.

7. The product as recited in claim 6 , wherein the peripheral outer surface of the pillar is rounded therealong from the bottom to the tip of the pillar.

8. The product as recited in claim 1 , wherein the pillar is SiC.

9. The product as recited in claim 1 , wherein the pillar is diamond.

10. The product as recited in claim 1 , comprising an array of the pillars extending from a substrate, the pillars and substrate having the same bulk composition throughout.

11. The product as recited in claim 10 , wherein at least some of the pillars have an inner channel extending along a longitudinal axis thereof.

12. The product as recited in claim 11 , wherein the substrate has channels therethrough in fluid communication with the channels of at least some of the pillars.

13. A method of making the product as recited in claim 1 , the method comprising:
masking a carbon-containing single crystal for defining masked regions and unmasked regions on the single crystal;
performing a plasma etch for removing portions of the unmasked regions of the single crystal, thereby defining a pillar in each unmasked region; and
performing a chemical etch on the pillars at a temperature between 1200° C. and 1600° C. for selectively reducing a width of each pillar.

14. The method as recited in claim 13 , wherein performing the chemical etch includes contacting the pillars with a gas having at least one etchant, the etchant being selected from the group consisting of: H, Cl, Br, and I.

15. The method as recited in claim 14 , comprising adding a defined amount of oxygen to the gas for reducing an extent of crystallographic etching.

16. The method as recited in claim 13 , wherein each pillar comprises a bottom and a tip opposite the bottom, wherein the width of the pillar measured 1 nm below the tip is less than 700 nm.

17. The method as recited in claim 13 , wherein each pillar has an inner channel extending along a longitudinal axis thereof.

18. A product, comprising:
an elongated carbon-containing pillar having a bottom and a tip opposite the bottom,
wherein the width of the pillar measured 1 nm below the tip is less than 700 nm,
wherein the pillar has an inner channel extending along a longitudinal axis thereof.

19. The product as recited in claim 18 , wherein the pillar extends from a single crystal substrate having a bulk composition that is the same as the bulk composition of the pillar, wherein the substrate has a channel therethrough in fluid communication with the channel of the pillar.

Assignees

• L Livermore Nat Security Llc

Inventors

• Frye Clint D
• Bora Mihail
• Conway Adam M
• Funaro Devin Joseph
• Grivickas Paulius Vytautas
• Hall David L
• Voss Lars F

Classifications

• B81C1/00531

  Dry etching · CPC title

• A61M2037/0053

  Methods for producing microneedles · CPC title

• B81B2201/055

  Microneedles · CPC title

• A61M2037/0023

  Drug applicators using microneedles · CPC title

• B81B1/008

  Microtips · CPC title