Methods and systems for metal-assisted chemical etching of substrates

1. A method for metal-assisted chemical etching, comprising:

providing a substrate;

depositing a non-spherical metal catalyst on a surface of the substrate, the non-spherical metal catalyst including a first portion including a first metal deposited on the surface of the substrate and a second portion including a second material deposited on the surface of the substrate;

etching the substrate by exposing the non-spherical metal catalyst and the substrate to an etchant solution including a composition of a fluoride etchant and an oxidizing agent; and

removing the etched substrate from the etchant solution.

2. The method of claim 1 , wherein the substrate is a silicon substrate.

3. The method of claim 1 , wherein the metal is selected from the group consisting of gold, silver, platinum, and tungsten.

4. The method of claim 1 , wherein the fluoride etchant is hydrofluoric acid (HF) and the oxidizing agent is hydrogen peroxide (H 2 O 2 ).

5. The method of claim 1 , wherein the non-spherical metal catalyst is patterned on the surface of the substrate.

6. The method of claim 5 , wherein the patterned metal catalyst includes a grid comprising lines of the metal.

7. The method of claim 6 , wherein the grid includes at least one protrusion extending from a first side of the grid.

8. The method of claim 6 , wherein areas between the lines of the grid are filled with material.

9. The method of claim 5 , further comprising:

patterning a second non-spherical metal catalyst on a surface of the substrate; and

further etching the substrate by simultaneously exposing the first and second non-spherical metal catalysts and the substrate to a second etchant solution.

10. The method of claim 9 , where the second etchant solution has a composition that is the same as the first etchant solution.

11. A method for metal-assisted chemical etching, comprising:

providing a substrate;

depositing a non-spherical metal catalyst on a surface of the substrate;

etching the substrate by exposing the non-spherical metal catalyst and the substrate to an etchant solution including a composition of a fluoride etchant and an oxidizing agent;

applying a magnetic field to the metal catalyst to direct the etching path within the substrate; and

removing the etched substrate from the etchant solution.

12. The method of claim 11 , wherein the non-spherical metal catalyst is a nanoparticle positioned on the surface of the substrate.

13. The method of claim 12 , wherein the metal catalyst is a nanodonut.

14. The method of claim 11 , wherein the non-spherical metal catalyst is patterned on the surface of the substrate.

15. The method of claim 14 , wherein the patterned metal catalyst is a dog-bone shaped nanostructure.

16. A method for metal-assisted chemical etching, comprising:

providing a substrate;

depositing a non-spherical metal catalyst on a surface of the substrate, the non-spherical metal catalyst including at least one protrusion extending from a side of the non-spherical metal catalyst;

etching the substrate by exposing the non-spherical metal catalyst and the substrate to an etchant solution including a composition of a fluoride etchant and an oxidizing agent, the at least one protrusion producing rotational movement of the non-spherical metal catalyst through the substrate during exposure to the etchant solution; and

removing the etched substrate from the etchant solution.

17. The method of claim 16 , wherein the non-spherical metal catalyst is patterned on the surface of the substrate.

18. The method of claim 17 , wherein the patterned metal catalyst includes a grid.

19. The method of claim 17 , wherein the patterned metal catalyst is formed using a plurality of materials.

20. The method of claim 16 , wherein the non-spherical metal catalyst includes a plurality of protrusions extending from the side of the non-spherical metal catalyst.