Patent Publication Number: US-2010119420-A1

Title: Abatement system having enhanced effluent scrub and moisture control

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. provisional patent application Ser. No. 61/112,679, filed Nov. 7, 2008, which is herein incorporated by reference in its entirety. 
    
    
     FIELD 
     Embodiments of the present invention generally relate to processing equipment, and more specifically to abatement systems for treating effluents. 
     BACKGROUND 
     Abatement systems are utilized at least in part for the removal of particles and/or hazardous effluent gases from an exhausting effluent stream prior to releasing the stream into the environment. For example, in the abatement system, the exhausting effluent stream may be combusted and then washed to remove particulates and/or water soluble effluents. In some abatement systems, the effluent stream is passed through a scrubber which can be utilized to remove particulates and/or hazardous effluents from the stream. 
     However, the inventors have discovered that in some applications, processing effluent with a scrubber may fail to adequately reduce hazardous gases, such as hydrogen fluoride (HF), silane (SiH 4 ), tetrafluorosilane (SiF 4 ) or the like, and/or particulate matter from the exhausting effluent stream. 
     Thus, the inventors have provided an improved abatement system that can advantageously further improve hazardous gas and particulate matter reduction from an effluent stream. 
     SUMMARY 
     Apparatus for improved treatment of effluents are provided herein. In some embodiments, an abatement system may include an exhaust conduit to flow an effluent stream therethrough; a plurality of packed beds disposed in the exhaust conduit to remove non-exhaustible effluents from the effluent stream; one or more spray jets to provide an effluent treating agent between adjacent packed beds, the effluent treating agent to remove non-exhaustible effluents from the effluent stream; and a dripper disposed in the exhaust conduit above an uppermost packed bed to provide the effluent treating agent in large droplets to wet and rinse particulate from an upper surface of the uppermost packed bed substantially without forming fine droplets. 
     In some embodiments, an abatement system may include an exhaust conduit to flow an effluent stream therethrough; three packed beds, disposed axially in the exhaust conduit and in a spaced apart relation, to remove non-exhaustible effluents from the effluent stream; one or more spray jets to provide an effluent treating agent between adjacent packed beds, the effluent treating agent to remove non-exhaustible effluents from the effluent stream; and a dripper disposed in the exhaust conduit above an uppermost packed bed to provide the effluent treating agent in large droplets, having an average diameter of between about 200 to 2000 microns, to wet and rinse particulate from an upper surface of the uppermost packed bed. Other and further embodiments of the present invention are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the invention depicted in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  depicts a schematic side view of a process apparatus in accordance with some embodiments of the present invention. 
         FIG. 2  depicts a schematic side view of a scrubber in accordance with some embodiments of the present invention. 
         FIGS. 3A-B  depicts bottom and end-facing views of a dripper in accordance with some embodiments of the present invention. 
         FIGS. 4A-C  side and bottom views of a dripper in accordance with some embodiments of the present invention. 
         FIG. 5  depicts a kinetic impactor and moisture trap in accordance with some embodiments of the present invention. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     Apparatus for improved treatment of effluents are provided herein. The inventive apparatus advantageously improves the capture of hazardous gases while maintaining and/or improving removal efficiency of particles from an exhausting effluent stream. 
       FIG. 1  depicts a schematic side view of a processing system  100  in accordance with some embodiments of the present invention. The exemplary processing system  100  includes a process chamber  102  coupled to an abatement system  104 . The abatement system  104  is configured to process an exhausting effluent stream from the process chamber  102  to remove particles and/or hazardous gases from the effluent prior to releasing the remaining effluent into the environment. 
     The process chamber  102  may be any suitable process chamber, such as one or more of a semiconductor, flat panel, photovoltaic, organic light emitting diode (OLED), microelectromechanical systems (MEMS), or other silicon or thin film processing systems. The process chamber  102  may be configured for etch, deposition, plasma or any suitable processes associated with the aforementioned processing systems. Exemplary, non-limiting process chambers may include AKT® 60K for Solar, PRODUCER® eHarp for CVD, or ENABLER® E5 for Etch, available from Applied Materials, Inc. of Santa Clara, Calif. 
     An exhausting effluent stream from the process chamber  102  is directed to the abatement system  104 , for example via appropriate conduits, pumps, valves, or the like (not shown). The abatement system  104  converts the effluent to an environmentally safe material, such as by removing non-desired components from the effluent, such as hazardous gases and/or particles from the effluent. 
     The abatement system  104  may be any suitable abatement system for receiving and processing the effluent from a process chamber, for example, the process chamber  104 . The abatement system  104  may be employed to abate a single process chamber or tool, or multiple process chambers and/or tools. The abatement system  104  may use, for example, thermal, wet scrubbing, dry scrubbing, catalytic, plasma and/or similar means for the treatment of the effluent, as well as processes for converting the effluent to less toxic forms. The abatement system  104  may further include multiple abatement systems for processing particular types of effluents from a process chamber or a plurality of process chambers or other processing equipment having effluent to be abated. One exemplary abatement system may be the MARATHON® system, available from Applied Materials, Inc. of Santa Clara, Calif. 
     The abatement system  104  may include a thermal reactor  106  (i.e., combustion reactor), a water quenching apparatus  108 , a separation tank  110 , and a scrubber  112 . The effluent stream, for example, including effluents such as a flammables and hydrocarbons, silanes, fluorocarbons, hydrogen, halogens, dopants, or the like may be flowed into the thermal reactor  106  of the abatement system  104  upon exhaust from the process chamber  102 . The thermal reactor  106  may, for example burn effluents, such as saturated hydrocarbons in an atmosphere of an oxygen-containing gas such as oxygen (O 2 ) to form carbon dioxide (CO 2 ) and water (H 2 O) which can be released into the environment. Further, the thermal reactor  106  may burn effluents, such as silanes, fluorocarbons, halogens, dopants, or the like in a similar atmosphere to form non-exhaustible effluents, such as hazardous gases (such as one or more of fluorine, chlorine, hydrogen chloride, hydrogen fluoride (HF), tetrafluorosilane (SiF 4 ), silicon dioxide (SiO 2 ), metal oxides, or the like), and/or particles, (such as silica (SiO 2 ), glass, metal oxides, organics, carbon, or the like), which must be removed from the exhausting effluent stream and not released into the environment. As used herein, the term non-exhaustible effluents means effluent that is not desired to be exhausted, for example due to environmental and/or safety regulations, and not effluent that is not capable of being exhausted. 
     The effluent stream treated by the thermal reactor  106  may next be flowed into the water quenching apparatus  108 , where the effluent stream is cooled by contact with water, such as through a water spray or the like. The water quenching apparatus  108  can act to quench steam, such as formed from the combustion of hydrogen (H 2 ) and a fuel, such as a hydrocarbon, into liquid water. The water quenching apparatus  108  can further act to remove large particles, such as between about 0.1 micrometer to about 1 millimeter sized solids, from the effluent stream. For example, the large particles may comprise silica (SiO 2 ), metal oxides, or metal halide. The remaining effluent stream (i.e., those effluents not removed by the water quenching apparatus  108 ) flows into the tank  110 , which is coupled to the water quenching apparatus  108 . The remaining effluent stream may include finer particles, and water droplets such as those between about 10 nanometers to about 10 micrometers in size. These finer particles may comprise similar materials to the larger particles discussed above. 
     The tank  110  may further aid the reduction of particles from the remaining effluent stream. For example, in some embodiments, the tank  110  may include a first chamber and a second chamber separated by a solid or perforated wall (not shown). Each chamber is partially filled with water to a level sufficient to prevent the effluent from flowing directly from the first chamber to the second chamber without going through the water or being contacted by condensable water vapor. 
     A blower or water inductor (not shown) may be coupled between the first and second chambers for removing the gaseous portion of the remaining effluent stream from the first chamber and injecting it directly into the water below the water level of the second tank. The gaseous portion may be injected into the water of the second chamber via a diffuser (not shown) which releases the gaseous portion of the remaining effluent stream into the water of the second chamber in the form of fine bubbles. The bubbles allow the gaseous portion to have high surface area contact with the water and condensable water vapor to efficiently removal particles trapped in the gaseous portion of the remaining prior to reaching the water level of the second chamber. The second chamber may further include a mechanical fan or stirrer (not shown) to improve mixing of the water with the bubbles of the gaseous portion of the remaining effluent stream. 
     The remaining gaseous portion of the effluent stream exits the tank  110  and enters the scrubber  112  to further remove any remaining particles and/or hazardous gases from the remaining gaseous portion of the effluent stream prior to exhaust into a factory exhaust system or the environment. 
       FIG. 2  depicts a schematic side view of the scrubber  112  in accordance with some embodiments of the present invention. The scrubber  112  includes an exhaust conduit  202  for flowing an exhausting effluent stream  204  (i.e., the remaining gaseous portion of the effluent stream received from the tank  110 ) therethrough. The exhaust conduit  202  may be any suitable shape to facilitate efficient removal of hazardous gases and/or particles from the effluent stream. For example, the exhaust conduit  202  may be cylindrical. The exhaust conduit  202  may comprise any suitable material compatible with abatement processes, for example, such as stainless steel, polyvinyl chloride (PVC), chlorinated PVC (CPVC), high nickel alloy, polypropylene, polyethylene, polyvinylidene fluoride (PVDF), or the like. 
     One or more packed beds  206  may be disposed in the exhaust conduit  202  for removing non-exhaustible effluents from the exhausting effluent stream  204  (three packed beds  206  illustratively shown in  FIG. 2 ). Each packed bed  206  may be spaced apart as illustrated in  FIG. 2 . In some embodiments, the number of packed beds  206  may be between about 2 to about 10. A length  208  of each packed bed  206  as defined along a central axis  210  of the exhaust conduit  202  may be between about 5 to about 30 inches, although other dimensions may be used as necessary or desired for a particular application. In some embodiments, an uppermost packed bed  212  has a first length greater than a second length of a lowermost packed bed  214 . In some embodiments, the first length of the uppermost packed bed  212  is between about 10 to about 15 inches. In some embodiments, the second length of the lowermost packed bed  214  is between about 5 to about 8 inches. In some embodiments, any packed bed between the uppermost and lowermost packed beds has a third length between about 5 to about 8 inches. The third length may be greater than or equal to the second length or less than or equal to the first length (i.e., equal to or between the length of the uppermost or lowest packed bed). 
     Each packed bed  206  further includes a plurality of non-exhaustible effluent sequestering objects  216  disposed between an upper and lower perforated plate  218 ,  219 . The non-exhaustible sequestering objects  216  may be in any suitable size and shape necessary to create a torturous path for the effluent stream  204 . The shape of each object  216  may include one or more of spherical, polyhedral, random, or the like. The size of each object  216  may have at least one dimension of between about ¼″ to about 2″ (such as an average diameter for approximately spherical shapes). Each object  216  may include any suitable material or materials for sequestering non-exhaustible effluents, such as high surface area material, for example, zeolites, alumina, spinel, glass, nickel, stainless steel, high nickel alloy, polypropylene, polyethylene, PVC, CPVC, PVDF, cellulose, or the like, or other materials, such as carbon rings, or the like. 
     The upper and lower perforated plates  218 ,  219  may act to hold the objects  216  in place in the exhaust conduit  202 . The perforated plates  218 ,  219  may include any suitable size, shape and pattern of holes  220  for passing the exhaust stream  204  therethrough. The size, shape and pattern of the holes  220  may be further utilized to control residence time of the exhaust stream in each packed bed and to distribute the gas flow evenly across the cross section of the scrubber. 206 . 
     The scrubber  112  further includes a plurality of spray jets  222  disposed in or about the walls of the exhaust conduit  202  (as shown) or across the cross section of the exhaust conduit  202  (not shown). In some embodiments, one or more spray jets  222  may be disposed adjacent to each packed bed  206 , or between each packed bed  222 . In some embodiments, one or more spray jets  222  may be disposed below the lowermost packed bed  214 . Each spray jet  222  may be coupled to an effluent treating agent source  223  to provide an effluent treating agent that interacts with exhausting effluent stream  204  to remove non-exhaustible effluents therefrom. The effluent treating agent may include one or more of water (H 2 O), a caustic, an acid, an ionic or non ionic surfactant, or an agglomerating agents. In some embodiments, the effluent treating agent may be water or water having one or more of a caustic, an acid, an ionic or non ionic surfactant, or an agglomerating agent mixed therein. In some embodiments where the effluent treating agent includes water, the water may be fresh water (sometimes referred to as fresh make-up water) or reticulated water from the tank  110 . 
     Each spray jet  222  may be any suitable shape or structure for dispensing the effluent treating agent. For example, each spray jet  222  may include a nozzle or other similar apparatus for dispensing the effluent treating agent as a spray, mist or the like. The spray jets  222  may be oriented about the wall of the exhaust conduit  202  in any suitable configuration appropriate to maximize interaction of the effluent treating agent with the effluent stream  204 . For example, several spray jets  222  may be disposed about the wall of the exhaust conduit  202  between adjacent packed beds  206  as illustrated in  FIG. 2 . 
     In some embodiments, the spray jets  222  may be adjustable for varying the intensity of the spray or the flow rate of the effluent treating agent. For some process recipes, or during idle mode, for example, the recirculating water flow rate and fresh water flow addition may vary as a function of time or process step. For some operating conditions, a fine mist or alternately large droplets of scrubbing fluid (e.g., the effluent treating agent) may be used at various axial positions along the conduit. Changing the water feed pressure can dynamically control the shape of the spray pattern. In some embodiments, the spray jets  222  disposed above the lowermost packed bed  214  may be configured to provide a fine mist. Sets of spray jets disposed above succeeding packed beds along the scrubber  112  may provide increasingly coarse (i.e., larger) average droplet sizes. The inventors have discovered that a fine mist, or any high surface area distribution of the effluent treating agent improves the sequestering of fine particles, such as silica (SiO 2 ) or the like, from the effluent stream  204 . However, the inventors have further discovered that such a fine mist may undesirably be carried along the effluent stream out of the scrubber and to atmosphere or other post-abatement effluent handling equipment, particularly if provided near the downstream end of the scrubber  112 . Accordingly, the arrangement of progressively coarser spray jets may provide particle reduction with a lower likelihood of droplets of the effluent treating agent being carried out of the scrubber  112  in the effluent stream due to the larger mass of the spray droplets. 
     To further assist in reducing the likelihood of droplets of the effluent treating agent being carried out of the scrubber  112 , in some embodiments, the uppermost packing bed  212  may be provided as a demister and used without spray jets  222  being provided downstream. In some embodiments, a dripper  224  may be disposed above the uppermost packed bed  212 . The dripper  224  may be disposed in the exhaust conduit  202  above the uppermost packed bed  212 . The dripper  224  may provide the effluent treating agent counter to a flow direction of the exhausting effluent stream  204  to remove non-exhaustible effluents therefrom. Rather than the fine mist or coarse spray provided by the spray jets  222 , the dripper  224  may provide large droplets of the effluent treating agent (e.g., a drip). The large droplets from the dripper  224  may cover the upper packing to create a wet surface without creating a mist from the spray. In some embodiments, a spray or fine mist may be defined as having an average droplet size from about 0.1 to 10 microns and the larger droplets used near the top of the fluid scrubber may range from about 200 to 2000 microns. The inventors have discovered that providing a coarse drip of effluent treating agent further improves the sequestering of hazardous gases, such as hydrogen fluoride (HF) or tetrafluorosilane (SiH 4 ) from the effluent stream  204  while reducing the fine mist carry over from fine mist generated below the reactor or lower (e.g., upstream) in the scrubber  112 . 
     In some embodiments, the dripper  224  comprises a second conduit  226  extending from a wall of the exhaust conduit  202  and across the diameter thereof. The second conduit  226  may extend completely across the exhaust conduit  202  (and may be supported by both sides of the exhaust conduit  202 ) or may be cantilevered into the exhaust conduit  202  and supported by only one side of the exhaust conduit  202  (as depicted in  FIG. 2 ). Embodiments of the dripper  224  including the second conduit  226  are illustrated in FIGS.  2  and  3 A-B. 
       FIG. 3A  depicts a bottom view of the second conduit  226  in accordance with some embodiments of the present invention. The second conduit  226  includes a plurality of outlets  302  disposed on a side  304  of the second conduit  226  facing the oncoming effluent stream for providing the effluent treating agent therefrom. In some embodiments, at least one of the outlets  302  is angled with respect to a central axis  210  of the exhaust conduit  226 . 
     The plurality of outlets  302 , and their varying diameters and geometries, can be arranged to provide a uniform droplet spray pattern and positional fluid flow rate that roughly corresponds to the shape of the exhaust conduit  226 . For example, as illustrated in  FIG. 3A , the plurality of outlets  302  can be arranged in a plurality of rows  306  disposed perpendicular to the central axis of the second conduit  226 . Each row  306  can extend partially along a circumference of the second conduit  226  on the effluent stream facing side  304  thereof. 
     The number of outlets and/or the spacing between outlets  302  in a row  306  can vary between different rows  306  along the second conduit  226  to provide the desired spray pattern. For example, the number of outlets and/or the spacing between outlets  302  may increase from rows  306  proximate the walls of the exhaust conduit  202  to rows  306  proximate a central axis  210  of the exhaust conduit  202 . In some embodiments, and as illustrated in  FIG. 3A , the number of outlets  302  in each row  306  increases and the spacing between each outlet  302  in each row  306  increases from rows near the walls of the exhaust conduit  202  to rows near the central axis  210  thereof. 
     The spacing of the outlets  302  in each row  306  may be varied, for example, by changing the angle of one or more outlets  302  in each row  306 , as illustrated in  FIGS. 3B-D . For example,  FIGS. 3B-D  depict cross-sectional views of the second conduit  226  along lines cutting through different rows  306  of the dripper  224 . 
     As illustrated, each row  306  may illustratively include one outlet ( FIG. 3B ), two outlets ( FIG. 3C ), or a three outlets ( FIG. 3D ). Other numbers of outlets or variations from row to row or along the second conduit  226  are contemplated. The one-outlet row may comprise one outlet  302  oriented parallel to the central axis  210  of the exhaust conduit  226 . The two-outlet row may comprise two outlets  302  symmetrically angled with respect to the central axis  210  of the exhaust conduit  226 . In some embodiments, each outlet  302  of the two-outlet row may be angled at about 45 degrees or less with respect to the central axis of the exhaust conduit. The three-outlet row may comprise three outlets  302 , where one central outlet is oriented parallel to the central axis of the exhaust conduit and is disposed between two outlets symmetrically angled with respect to a central axis of the exhaust conduit. In some embodiments, each angled outlet of the three-outlet row may be angled between about 30 to about 60 degrees with respect to the central axis of the exhaust conduit. 
       FIGS. 4A-C  depict an alternative embodiment of the dripper  224  in accordance with some embodiments of the present invention. For example, in  FIG. 4A , the dripper  224  includes a showerhead  402  centrally disposed in the exhaust conduit  226  above the uppermost packed bed  212 . Similar to the second conduit  226 , the showerhead  402  may provide the effluent treating agent at a desired flow rate and droplet size counter to the flow direction of the effluent stream  204  in a desired pattern, for example, corresponding to the shape of the exhaust conduit  226 . The showerhead  402  includes a plurality of outlets  404  for providing the effluent treating agent therefrom. In some embodiments, at least some of the outlets  404  are radially disposed about a central axis  210  of the exhaust conduit  226  and angled with respect thereto as shown in bottom and side views of the showerhead  402  in  FIGS. 4B-C . In some embodiments, at least one outlet  404  is centrally disposed along the central axis  210  of the exhaust conduit and parallel thereto. 
     Returning to  FIG. 2 , in some embodiments, a moisture suppression device  228  may be disposed downstream of the uppermost packed bed  212  (or the dripper  224 , when present) proximate the exit of the exhaust conduit  202  of the scrubber  112 . The moisture suppression device  228  may provide room air or cool dry air to dry out or reduce the humidity of the effluent stream. For example, the moisture suppression device  228  may have one or more inlets  230  that may be coupled to an air source  232  to provide air into the effluent stream  204 . As noted above, the air source  232  may provide room air or cool dry air to the effluent stream. 
     In operation and in some embodiments, and referring to  FIG. 2 , the exhausting effluent stream  204  comprising hazardous gases and/or particles enters the exhaust conduit  202  and may be exposed to a spray and/or mist of the effluent treating agent provided by the plurality of spray jets  222  disposed prior to the lowermost packed bed  214 . The exhausting effluent stream  204  then enters the lowermost packed bed  214  where the effluent stream  204  moves through a torturous path of the effluent sequestering objects  216  where hazardous gases and/or particles are removed from the effluent stream  204 . The effluent stream  204  exits the lowermost packed bed  214  and is again treated with the effluent treating agent provided by a plurality of the spray jets  222  disposed above the lowermost packed bed  212 . In some embodiments, each successive treatment of the effluent treating agent provided by the spray jets  222  may be a more coarse spray than the previous treatment to limit the quantity of fine spray droplets entrained in the effluent stream  204 . The effluent stream  204  continues to flow upward through the plurality of packed beds  206  in a torturous path until, in some embodiments, it is met with the drip of large droplets of the effluent treating agent provided by the dripper  224  above the uppermost packed bed  212 . The large droplets provided by the dripper  224  may further aid in the sequestering of hazardous gases from the effluent stream  204  prior to release into the environment or factory exhaust system while not providing small droplets of the effluent treating agent that may be carried out of the scrubber  112  via the flow of the effluent stream. In some embodiments, room air or cool dry air may be provided to the remaining effluent stream by the moisture suppression device  228  to further cool and dry the effluent stream. 
     In some embodiments, prior to release into the environment or factory exhaust system, the effluent stream  204  may flow through an optional moisture trap  500  disposed downstream of the scrubber  112  (or at a downstream end of the exhaust conduit  202  of the scrubber  112 , for example downstream of the uppermost packed bed  212 , the dripper  224  when present, and the moisture suppression device  228  when present).  FIG. 5  depicts a kinetic impactor and moisture trap  500  in accordance with some embodiments of the present invention. The kinetic impactor and moisture trap  500  includes a first conduit  501  disposed in-line with the abatement exhaust, for example in-line with exhaust conduit  202  of the scrubber  112 . Flanges  510  may be provided at either end of the first conduit  501  for ease of installation and removal. In some embodiments, the first conduit  501 , and the kinetic impactor and moisture trap  500  overall, may have a low vertical footprint to facilitate use in small spaces. For example, in some embodiments the first conduit  501  may have a length  512  of about 12 inches. 
     A second conduit  502  is fluidly coupled to the first conduit  501  at a slight elevated angle thereto. In some embodiments, the second conduit  502  may have a length of between about two to three feet. A central diverter partition  504  may be disposed within the second conduit  502  to force the effluent stream  204  around a longer/torturous flow path to exit the conduit  501 . The partition  504  provides a surface for moisture (e.g., water vapor) from the exhaust stream  204  to condense thereon. Once condensed, the captured moisture may flow back into the exhaust conduit  202  via a drain  506  disposed in the partition  504  proximate the intersection of the partition  504  and the base of second conduit  502 . In some embodiments, a flange  508  may be provided on an outer end of the second conduit  502  (opposite the base). The flange may be configured to provide a viewpoint into the moisture trap  500  for inspection and/or a connection for washing down the kinetic impactor and moisture trap  500 . 
     In some embodiments, a cooling jacket  514  may be provided to cool the effluent flowing through the moisture trap. The cooling jacket may include a cooling coil  516  wrapped around the second conduit  502  to remove heat from the surfaces of the second conduit  502 , which then facilitates greater heat transfer from the effluent to the cooled surfaces of the second conduit  502 . The cooling coil  516  may be part of a chiller loop (not shown) to flow a heat transfer fluid through the cooling coil  516 . 
     Thus, apparatus for improved treatment of effluents are provided herein. The inventive apparatus advantageously improves the capture of hazardous gases while further maintaining removal efficiency of particles from an exhausting effluent stream. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.