Method and apparatus for using molten aluminum to abate PFC gases from a semiconductor facility

Abstract

This application is dedicated to the public. A method and apparatus for reducing the emissions of a fluorinated gas from a wafer processing facility begins by providing a fluorinated exhaust gas from wafer processing tools (10) through (16) via an input line (17). The fluorinated exhaust gas is then optionally gettered via an gettering system (18) to remove oxygen from the exhaust gas. After gettering, the fluorinated exhaust gas is directed to a molten aluminum bath (44). The fluorine in the exhaust gas reacts with the aluminum to form AlF 3 . A measurement device (56) is used to monitor the amount of fluorine being exhausted from the molten aluminum bath (44). When the amount of fluorine in the exhaust is too high, the molten aluminum bath (44) is saturated with fluorine. The bath is then cooled to form an inert solid brick of AlF 3 . Therefore, fluorinated gases which are detrimental to the environment are cost-effectively removed from the output of a wafer fabrication facility.

We claim: 
     
       1. An apparatus comprising: a housing;   a molten metal region contained within the housing; and   an housing input line for providing fiuorinated gas to the molten metal region wherein fluorine within the fiuorinated gas is gettered by the molten metal region.   
     
     
       2. The apparatus of claim 1 further comprising: an oxygen gettering system coupled to the housing input line for filtering oxygen from the fiuorinated gas.   
     
     
       3. The apparatus of claim 2 wherein the oxygen gettering system comprises copper regions having a gettering input line and a gettering output line, the gettering output line of the copper region being coupled to the housing input line and the gettering input line receiving the fiuorinated gas, the copper region removing oxygen from the fiuorinated gas. 
     
     
       4. The apparatus of claim 3 wherein the oxygen gettering system comprises heating elements surrounding the copper region for heating the copper region during regeneration processing. 
     
     
       5. The apparatus of claim 4 comprising: a first valve located at the gettering input line for controlling a flow of the fiuorinated gas to the oxygen gettering system;   a second valve located at the gettering output line for controlling a flow of the fiuorinated gas to the molten metal region.   
     
     
       6. The apparatus of claim 4 comprising: a first valve located at the gettering input line for controlling a flow of regeneration gas to the oxygen gettering system;   a second valve located at the gettering output line for controlling a flow of regeneration exhaust to a regeneration output, the first and second value being turned on in order to scrub oxygen from the copper regions.   
     
     
       7. The apparatus of claim 1 wherein the molten metal region is a molten aluminum region. 
     
     
       8. The apparatus of claim 1 wherein the molten metal region is contained within a ceramic container. 
     
     
       9. The apparatus of claim 1 wherein the molten metal region is contained within a ceramic container wherein a back-up inconel container surrounds the ceramic container. 
     
     
       10. The apparatus of claim 1 wherein the molten metal region is contained within a ceramic container wherein a back-up inconel container surrounds the ceramic container and wherein a inconel furnace well surrounds the back-up inconel container within the housing. 
     
     
       11. The apparatus of claim 1 wherein heating elements are positioned within the housing and in close proximity to the molten metal regions so that the heating elements will maintain the molten metal region in a molten state. 
     
     
       12. The apparatus of claim 1 wherein the housing input line is coupled to a porous ceramic plug within the molten metal region for dispersing the fluorinated gas within the molten metal region. 
     
     
       13. The apparatus of claim 1 wherein an inert carrier gas source is coupled to the housing for providing inert gas to an environment which surrounds the molten metal region. 
     
     
       14. The apparatus of claim 1 wherein a housing output line is coupled to the housing for providing output gas from an environment within the housing and adjacent the molten metal region. 
     
     
       15. The apparatus of claim 14 wherein the housing output line is coupled to a measurement device which is used to monitor an amount of fluorine consumed in the molten metal region by monitoring the output gas. 
     
     
       16. The apparatus of claim 15 wherein the housing output line is coupled to a measurement device wherein the measurement device is a device selected from a group consisting of: a mass spectrometer and a gas chromatograph. 
     
     
       17. The apparatus of claim 14 wherein the housing output line is coupled to a fabrication scrubber for further cleaning of the output gas. 
     
     
       18. The apparatus of claim 1 wherein the housing input line is coupled to a plurality of semiconductor wafer processing tools so that fluorinated gas is filtered from the plurality of semiconductor wafer processing tools. 
     
     
       19. An apparatus comprising: a plurality of semiconductor wafer processing tools having a tool output for providing fluorinated carbon gas;   an oxygen gettering system for removing oxygen from the fluorinated carbon gas, the oxygen gettering system having a gettering output;   a molten aluminum bath coupled to the gettering output, the fluorinated carbon gas being injected into the molten aluminum bath so that the molten aluminum bath filters fluorine atoms from the fluorinated carbon gas, the molten aluminum bath having a bath output; and   a measurement device coupled to the bath output for determining an efficiency of fluorine removal in the molten aluminum bath wherein notification is given when the efficiency of fluorine removal in the molten aluminum bath obtains a notification threshold.