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- Nachgewiesen in: USPTO Patent Applications
- Sprachen: English
- Document Number: 20150097485
- Publication Date: April 9, 2015
- Appl. No: 14/048493
- Application Filed: October 08, 2013
- Assignees: XEI Scientific Inc. (Redwood, CA, US)
- Claim: 1. A plasma processing apparatus for use with a vacuum instrument having a vacuum chamber of selected volume and said vacuum volume evacuated by a high vacuum pump to a pressure below about 1 Pa, the plasma cleaning apparatus comprising: a plasma chamber in fluid communication with the vacuum chamber; a plasma excitation device contained in the plasma chamber; a gas chamber in fluid communication with the plasma chamber, the gas chamber having a volume about 1/500 to 1/2000 of the selected volume of the vacuum chamber; a valve between the plasma chamber and the gas chamber, the valve selectively permitting flow between the gas chamber and the plasma chamber; a gas source in fluid communication with the gas chamber; and a flow restrictor between the gas source and the gas chamber, the flow restrictor limiting the gas flow into the gas chamber to less than about 25 sccm (standard cubic centimeters per minute) to minimize heating in the vacuum pump, wherein, with the plasma excitation device energized, upon opening the valve, pressure in the plasma chamber rises above about 10 Pa to enable plasma ignition, and gas pressure in the plasma chamber drops to a pressure sufficient to maintain a plasma while the valve remains open admitting gas after plasma ignition.
- Claim: 2. The plasma apparatus of claim 1, wherein the high vacuum pump is a turbo-molecular pump.
- Claim: 3. The plasma apparatus of claim 1, wherein the plasma excitation device is a hollow cathode powered by radio frequency electricity at 13.56 Mz.
- Claim: 4. The plasma apparatus of claim 1, wherein the flow restrictor is an orifice plate.
- Claim: 5. The plasma apparatus of claim 1, wherein the flow restrictor is a needle valve.
- Claim: 6. The plasma processing apparatus of claim 1, wherein the plasma is used for plasma cleaning of the vacuum chamber and surfaces therein.
- Claim: 7. The plasma cleaning apparatus of claim 6, wherein the gas is selected from O2, N2, air, Ar, He, H2O, H, NH3 and mixtures thereof.
- Claim: 8. The plasma cleaning apparatus of claim 1, wherein the pressure sufficient to maintain a plasma is between about 0.5 Pa and 7 Pa.
- Claim: 9. A method of igniting a plasma in a plasma chamber including a plasma excitation device to operate in a vacuum chamber that is pumped by a high vacuum turbo molecular pump, the plasma chamber being in fluid communication with the vacuum chamber, the method comprising the steps of: a-selectively admitting a selected volume of gas into the plasma chamber, the selected volume of gas being between about 1/500 and 1/2000 the volume of the vacuum chamber to temporarily raise pressure in the plasma chamber to a level sufficient to aid in the ignition of the plasma; b-simultaneously with the admitting step, igniting a plasma in the plasma chamber by energizing the plasma excitation device; c-continuing to flow gas through the plasma chamber at a flow rate less than about 25 sccm (standard cubic centimeters per minute) to maintain an operation pressure range in the plasma chamber sufficient for maintaining the plasma while the plasma excitation device is energized and without overheating the high vacuum pump.
- Claim: 10. The method of claim 9, wherein the operation pressure range is between about 0.5 and 7 Pa.
- Claim: 11. The method of claim 9, wherein the step of igniting plasma comprises energizing a hollow cathode in the plasma chamber with radio frequency electricity at about 13.65 mHz.
- Claim: 12. The method of claim 9, wherein the step of admitting a volume of gas into the plasma chamber comprises opening a valve between the plasma chamber and a gas chamber containing the gas and having a volume between 1/500 and 1/2000 that of the vacuum chamber.
- Claim: 13. The method of claim 9, wherein the gas is selected from O2, N2, air, Ar, He, H2O, H, NH3 and mixtures thereof.
- Claim: 14. A plasma cleaning apparatus for use with a vacuum instrument having a vacuum chamber of selected volume that may be evacuated by an oil free high vacuum pump such as a turbo-molecular pump to a base pressure below about 1 Pa, the plasma cleaning apparatus comprising: a plasma chamber in fluid communication with the vacuum chamber; a plasma excitation device contained in the plasma chamber; a gas chamber in fluid communication with the plasma chamber, the gas chamber having a volume about 1/500 to 1/2000 of the selected volume of the vacuum chamber; a valve between the plasma chamber and the gas chamber, the valve selectively permitting flow between the gas chamber and the plasma chamber, wherein, upon opening the valve, gas is admitted into the plasma chamber and pressure in the plasma chamber rises temporarily to above about 10 PA so plasma ignition can be obtained when the plasma excitation device is energized, a gas source in fluid communication with the gas chamber; and a flow restriction between the gas source and the gas chamber, the flow restriction having a maximum flow rate therethrough of about 25 sccm. (standard cubic centimeters per minute) so that pressure in the plasma chamber remains sufficient after plasma ignition to maintain plasma conduction and to avoid overloading or heating of the high vacuum pump.
- Claim: 15. The plasma cleaning apparatus of claim 14, wherein the plasma exciter is a hollow cathode powered by radio frequency electricity at 13.56 Mz.
- Claim: 16. The plasma cleaning apparatus of claim 14, wherein the flow restrictor means is an orifice plate.
- Claim: 17. The plasma cleaning apparatus of claim 14, wherein the flow restrictor means is a needle valve.
- Claim: 18. The plasma cleaning apparatus of claim 14, wherein the gas is selected from O2, N2, air, Ar, He, H2O, H, NH3 and mixtures thereof.
- Claim: 19. The plasma cleaning apparatus of claim 14, wherein pressure is maintained in the plasma chamber between about 0.5 Pa and about 7 Pa after plasma ignition.
- Current U.S. Class: 31511/121
- Current International Class: 01
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