Coating of nano-scaled cavities
Methods, systems, and apparatus for coating the internal surface of nano-scale cavities on a substrate are contemplated. A first fluid of high wettability is applied to the nano-scale cavity, filling the cavity. A second fluid carrying a conductor or a catalyst is applied over the opening of the nano-scale cavity. The second fluid has a lower vapor pressure than the first fluid. The first fluid is converted to a gas, for example by heating the substrate. The gas exits the nano-scale cavity, creating a negative pressure or vacuum in the nano-scale cavity. The negative pressure draws the second fluid into the nano-scale cavity. The conductor is deposited on the interior surface of the nano-scale cavity, preferably less than 10 nm thick.
1. A method of depositing a material on an interior surface of a cavity in a substrate, the method comprising:
exposing the cavity of the substrate to a fluid vapor and filling the cavity at least partially with the fluid vapor;
covering the cavity with a fluid having a material source, wherein the fluid has a lower temperature than the fluid vapor;
cooling the fluid vapor proximal to the fluid to reduce a volume of the fluid vapor in the cavity, thus creating a negative pressure in the cavity;
drawing the fluid into the cavity by way of the negative pressure; and
depositing the material from the material source onto the interior surface of the cavity.
2. The method of claim 1 , wherein the fluid vapor is a pure fluid or a combination of fluids.
3. The method of claim 1 , wherein the fluid further comprises a non-fluid substance.
4. The method of claim 1 , wherein the cavity has an opening with a diameter no more than 10 μm.
5. The method of claim 1 , wherein the cavity is less than 10 mm deep.
6. The method of claim 1 , wherein the cavity is at least one of a trench, a through hole, a blind via, or a buried via.
7. The method of claim 1 , wherein the substrate comprises at least one of a polymer, a metal, a ceramic, a crystal, a glass, a dielectric, and a composite material.
8. The method of claim 1 , further comprising the step of forming the cavity in the substrate.
9. The method of claim 1 , wherein the fluid comprises an organic solvent.
10. The method of claim 1 , wherein the difference in vapor pressure between the fluid and the fluid vapor is at least 100 mmHg.
11. The method of claim 1 , wherein the fluid vapor has high wettability.
12. The method of claim 1 , wherein the fluid vapor has a contact angle with the substrate of less than 90 degrees.
13. The method of claim 1 , wherein the fluid vapor has a surface tension no more than 30 mN/m at standard temperature and pressure (STP).
14. The method of claim 1 , wherein the fluid vapor has a vapor pressure that is higher than water vapor pressure at STP.
15. The method of claim 1 , wherein the material source comprises a carboxylate and a metal.
16. The method of claim 1 , wherein the material is a metal.
17. The method of claim 1 , wherein the material is deposited on the interior surface of the cavity no more than 100 nm thick.
18. The method of claim 1 , the material comprises at least one of a conductor, a semiconductor, a catalyst, or a combination thereof.