Method and apparatus for treating a substrate with dense fluid and plasma
View Patent ↗The present invention is a method, process and apparatus for selective cleaning, drying, and modifying substrate surfaces and depositing thin films thereon using a dense phase gas solvent and admixtures within a first created supercritical fluid anti-solvent. Dense fluids are used in combination with sub-atmospheric, atmospheric and super-atmospheric plasma adjuncts (cold and thermal plasmas) to enhance substrate surface cleaning, modification, precision drying and deposition processes herein. Moreover, conventional wet cleaning agents such as hydrofluoric acid and ammonium fluoride may be used with the present invention to perform substrate pre-treatments prior to precision drying and cleaning treatments described herein. Finally, dense fluid such as solid phase carbon dioxide and argon may be used as a follow-on treatment or in combination with plasmas to further treat a substrate surface.
1. A method of treating a substrate containing a contaminant comprising the sequential steps of:
positioning the substrate within a vessel;
pretreating the substrate to at least partially remove the contaminant;
pressurizing the vessel;
introducing a liquid or supercritical phase solvent into the vessel;
contacting the liquid or supercritical phase solvent with the substrate for a first selected period of time to further at least partially remove the contaminant from the substrate;
depressurizing the vessel to transition the liquid or supercritical phase solvent into a gaseous phase solvent, the depressurization occurring without subjecting the substrate to the atmosphere;
subjecting the vessel to an electric field to transition the gaseous phase solvent into a plasma phase solvent; and
contacting the plasma phase solvent with the substrate for a second selected period of time to further treat the substrate.
2. The method of claim 1 wherein pretreating the substrate comprises the sequential steps of:
pressurizing the vessel;
introducing a supercritical phase anti-solvent into the vessel and contacting the substrate with the anti-solvent;
introducing a pretreatment solvent into the pressurized vessel and contacting the substrate with the pretreatment solvent to at least partially remove the contaminant from the substrate and into the pretreatment solvent;
removing the pretreatment solvent containing the at least partially removed contaminant from the vessel; and
depressurizing the vessel to remove the anti-solvent from the substrate.
3. The method of claim 2 wherein the anti-solvent includes nitrogen, argon, helium or oxygen.
4. The method of claim 2 wherein the pretreatment solvent includes carbon dioxide, nitrous oxide, ammonia, fluorocarbons, xenon or sulfur hexafluoride.
5. The method of claim 2 wherein the pretreatment solvent includes either liquid phase solvent or supercritical phase solvent.
6. The method of claim 1 wherein the vessel is pressurized to a pressure between about 850 psi and about 1500 psi.
7. The method of claim 1 wherein the vessel is depressurized to form a vacuum.
8. The method of claim 7 wherein the vessel is depressurized to a pressure between about 150 mTorr and 300 mTorr.
9. The method of claim 1 wherein the plasma phase solvent is between about 15 degrees Celsius and about 60 degrees Celsius.
10. The method of claim 1 wherein the liquid or supercritical phase solvent includes carbon dioxide.