Formation of superhydrophobic surfaces
Technologies are described for methods and systems effective for etching nanostructures in a substrate. The methods may comprise depositing a patterned block copolymer on the substrate. The methods may comprise applying a precursor to the patterned block copolymer to generate an infiltrated block copolymer. The precursor may infiltrate into the first polymer block domain and generate a material. The methods may comprise applying a removal agent effective to remove the polymer block domains to the infiltrated block copolymer to generate a pattern of the material. The methods may comprise etching the substrate. The pattern of the material may mask the substrate to pattern the etching. The etching may be performed under conditions to produce nanostructures in the substrate. The methods may comprise removing the pattern of the material and coating the nanostructures and the surface of the substrate with a hydrophobic coating.
1. A method for etching conical nanostructures in a substrate, the method comprising:
depositing a patterned block copolymer on the substrate, wherein the patterned block copolymer includes a first polymer block domain and a second polymer block domain;
applying a precursor to the patterned block copolymer on the substrate to generate an infiltrated block copolymer on the substrate, wherein the precursor infiltrates into the first polymer block domain and generates a material of metal oxide dots in the first polymer block domain and the precursor does not infiltrate into the second polymer block domain;
applying a removal agent to the infiltrated block copolymer on the substrate to generate a pattern of the material on the substrate, wherein the removal agent is oxygen plasma and is effective to remove the first polymer block domain and the second polymer block domain from the substrate, and is not effective to remove the material in the first polymer block domain;
plasma etching the substrate, wherein the pattern of the material on the substrate masks the substrate to pattern the etching and the etching is performed under etch times sufficiently long enough for metal oxide dots to fall off and form a superhydrophobic surface of etched conical nanostructures, and wherein the etched conical nanostructures have a re-entrant curvature;
removing the pattern of the material from the substrate; and
coating the etched conical nanostructures and the surface of the substrate with a hydrophobic coating.
2. The method of claim 1 , wherein the nanostructures are patterned in an array with distances of about 30 nm to about 60 nm between nanostructure centers.
3. The method of claim 1 , wherein an aspect ratio of the height to average width of the nanostructures is about 1:1 to about 20:1.
4. The method of claim 1 , wherein the substrate is a polymer, silicon nitride, glass, or silicon.
5. The method of claim 1 , wherein the block copolymer is polystyrene-block-poly(methylmethacrylate).
6. The method of claim 1 , wherein the precursor is a metal organic precursor.
7. The method of claim 6 , wherein the metal organic precursor is tri-methyl aluminum (TMA).
8. The method of claim 1 , wherein the substrate is silicone, the plasma etching is with a plasma that is 50% oxygen, 50% sulfur hexafluoride (SF 6 ) and the plasma etching is performed at −100° C.
9. The method of claim 1 , wherein the substrate is silicone, the plasma etching is hydrogen bromide (HBr):chlorine (Cl 2 ):oxygen (O 2 )=100:100:25 standard cubic centimeter per minute (sccm) and the plasma etching is performed at room temperature.
10. The method of claim 1 , wherein the removing the pattern of the material is performed with a diluted acid.
11. The method of claim 1 , wherein the hydrophobic coating is octadecyltrichlorosilane.
12. A method for etching conical nanostructures in a substrate, the method comprising:
depositing a patterned block copolymer on the substrate, wherein the patterned block copolymer includes a first polymer block domain and a second polymer block domain;
applying a precursor to the patterned block copolymer on the substrate to generate an infiltrated block copolymer on the substrate, wherein the precursor infiltrates into the first polymer block domain and generates a material of metal oxide dots in the first polymer block domain and the precursor does not infiltrate into the second polymer block domain;
applying a removal agent to the infiltrated block copolymer on the substrate to generate a pattern of the material on the substrate, wherein the removal agent is oxygen plasma and is effective to remove the first polymer block domain and the second polymer block domain from the substrate, and is not effective to remove the material in the first polymer block domain;
plasma etching the substrate, wherein the pattern of the material on the substrate masks the substrate to pattern the etching and the etching is performed under etch times sufficiently long enough for metal oxide dots to fall off and form a superhydrophobic surface of etched conical nanostructures, and wherein the etched conical nanostructures have a re-entrant curvature and wherein the etched conical nanostructures are sized, shaped, and arranged so that when water contacts the etched conical nanostructures the water forms a contact angle above 160 degrees with the etched conical nanostructures in the substrate, and where the etched conical nanostructures are patterned in an array with distances of about 5 nm to about 100 nm;
removing the pattern of the material from the substrate; and
coating the etched conical nanostructures and the surface of the substrate with octadecyltrichlorosilane.