Method and apparatus for removing substances from gases

Abstract

The present invention concerns a method and an apparatus for removing substances from gases discharged from gas phase reactors. In particular, the invention provides a method for removing substances contained in gases discharged from an ALD reaction process, comprising contacting the gases with a “sacrificial” material having a high surface area kept at essentially the same conditions as those prevailing during the gas phase reaction process. The sacrificial material is thus subjected to surface reactions with the substances contained in the gases to form a reaction product on the surface of the sacrificial material and to remove the substances from the gases. The present invention diminishes the amount of waste produced in the gas phase process and reduces wear on the equipment.

What is claimed is:  
     
         1 . A method for removing substances contained in exhaust gases discharged from gas phase reaction processes, comprising: 
 carrying excess reactant from gas phase pulses of an atomic layer deposition (ALD) process conducted upon a deposition substrate under a first set of reaction conditions; and    directing the excess reactant to contact a sacrificial material downstream of the substrate and maintained at substantially the first set of reaction conditions.    
     
     
         2 . The method of  claim 1 , wherein the sacrificial material comprises a porous substrate.  
     
     
         3 . The method of  claim 2 , wherein directing comprises conducting the ALD process on the sacrificial material to leave a sacrificial layer having a composition that is substantially the same as a layer formed by the ALD process upon the deposition substrate.  
     
     
         4 . The method of  claim 2 , wherein the porous material comprises a material selected from the group consisting of porous graphite materials, porous ceramics, alumina, silica and glass wool.  
     
     
         5 . The method of  claim 1 , wherein the excess reactant includes a halide-containing gas.  
     
     
         6 . The method of  claim 5 , wherein the halide-containing gas comprises a chloride-containing gas.  
     
     
         7 . The method of  claim 1 , wherein the substrate and the sacrificial material are maintained within a single reaction space.  
     
     
         8 . The method of  claim 1 , wherein the sacrificial material is placed in a downstream reaction space housing that is connected to an upstream reaction space housing the substrate.  
     
     
         9 . The method of  claim 1 , wherein the sacrificial material has a surface area between about 10 m 2 /g and 2000 m 2 /g.  
     
     
         10 . The method of  claim 1 , wherein at the first set of conditions the deposition substrate and sacrificial material are at a temperature between about 200° C. and 500° C.  
     
     
         11 . The method of  claim 10 , wherein at the first set of conditions the deposition substrate and the sacrificial material are subjected to a pressure between about 1 mbar and 100 mbar.  
     
     
         12 . The method of  claim 1 , wherein the sacrificial material has a surface area sufficient to react substantially all of the excess reactant.  
     
     
         13 . The method of  claim 1 , wherein the sacrificial material comprises a porous material having an average pore size of about 10 μm to 100 μm.  
     
     
         14 . An apparatus for removing substances contained in gases discharged from a gas phase reaction process, comprising a reaction zone configured to receive exhaust flow from the reaction process, the reaction zone including a sacrificial material maintainable at a set of conditions substantially the same as those prevailing during the reaction process.  
     
     
         15 . The apparatus of  claim 14 , wherein the reaction zone includes a plurality of gas flow channels for feeding the exhaust flow from the reaction process into the sacrificial material and discharge gas channels for discharging gas from the material with a high surface area.  
     
     
         16 . The apparatus of  claim 15 , wherein the reaction zone further comprises baffles to define a serpentine path through the gas flow channels.  
     
     
         17 . The apparatus of  claim 14 , wherein the sacrificial material is porous.  
     
     
         18 . The apparatus of  claim 17 , wherein the sacrificial material has a surface area between about 10 m 2 /g and 2000 m 2 /g.  
     
     
         19 . The apparatus of  claim 18 , wherein has a surface area between about 100 m 2 /g and 1500 m 2 /g.  
     
     
         20 . The apparatus of  claim 17 , wherein the sacrificial material comprises a material selected from the group consisting of porous graphite materials, porous ceramics, alumina, silica and glass wool.  
     
     
         21 . The apparatus of  claim 14 , wherein the reaction zone includes a heating system for maintaining the sacrificial material at a temperature between about 50° C. and 600° C.  
     
     
         22 . The apparatus of  claim 14 , wherein the reaction zone includes a heating system for maintaining the sacrificial material at a temperature between about 200° C. and 500° C.  
     
     
         23 . The apparatus of  claim 14 , wherein the reaction zone is arranged within a common reactor shell with an upstream process region in which the reaction process is carried out upon a substrate.  
     
     
         24 . The apparatus of  claim 14 , wherein the reaction zone is arranged inside a separate reaction vessel downstream of a process chamber in which the reaction process is carried out upon a substrate.  
     
     
         25 . The apparatus of  claim 14 , configured for an atomic layer deposition (ALD) reaction process.  
     
     
         26 . The apparatus of  claim 25 , wherein the sacrificial material has a surface area sufficient to react by the ALD reaction process substantially all excess reactant from the ALD reaction process conducted upstream on at least one deposition substrate.