Patent Publication Number: US-9416919-B2

Title: Compact hazardous gas line distribution enabling system single point connections for multiple chambers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Application Ser. No. 61/889,875, filed Oct. 11, 2013, of which is incorporated by reference in its entirety. 
    
    
     FIELD 
     Embodiments described herein generally relate to a gas line distribution system having single point connections for multiple chambers. 
     BACKGROUND 
     Semiconductor fabrication plants (FABs) and other research, industrial, and medical operations require the use of a variety gases. Gas lines carry the required gases to their points of use. Safety codes require that if gas lines carrying hazardous gases use fittings, the fittings must be located inside an exhausted enclosure. Safety codes also require a high exhaust flow through the exhausted enclosure, which causes the size of the exhausted enclosure to become impractically large and take up valuable working space. 
     Exhausted enclosures can be avoided if fittings are not used, such as if an all-welded line system is used. All-welded line systems maintain safety and security like exhausted enclosures, but all-welded line systems involve an extra level of complexity since the welded lines need to be fabricated section-by-section within the facility. All-welded line systems are also extremely expensive and take a long time to construct. Furthermore, many gas lines carrying hazardous gases need to have double containment, which greatly increases the cost and level of complexity. Therefore, all-welded line systems are not a satisfactory solution. 
     The cost of running an individual gas line using current methods is high. Facilities often require a large number of gas lines, which quickly amplifies the total cost of running gas lines. For example, multiple processing chambers within a FAB may each require the same twenty to thirty gases to carry out their operations. Using conventional methods, twenty to thirty individual gas lines would need to be run to each of the multiple processing chambers. In that common situation, the cost of providing gas lines to FAB equipment rapidly becomes extraordinarily expensive. As the complexity of a FAB or other facility continues to increase, so will the cost of providing the required gas lines. 
     As the foregoing illustrates, what is needed in the art is a safe, inexpensive, and convenient method for delivering a plurality of gas lines to different points of use within a FAB or other research, industrial, or medical facility. 
     SUMMARY 
     Embodiments disclosed herein use a vacuum source to cost-effectively and safely enable the delivery of at least one gas line contained within a vacuum conduit to at least one point of use. More specifically, embodiments disclosed herein include a vacuum gas delivery system. A vacuum gas delivery system includes a vacuum system and a gas delivery system wherein the gas delivery system is housed within the vacuum system. In an exemplary embodiment, a vacuum source is used to safely deliver the same one or more gas lines to each of one or more processing chambers within a FAB by maintaining a vacuum conduit that surrounds the individual gas lines at less than atmospheric pressure as the gas lines travel through the FAB or under the FAB floor. Embodiments allow the delivery of each gas to each chamber using a single feed gas line for each gas. 
     A method is disclosed for safely enabling the delivery of at least one individual gas line to at least one point of use in a facility comprising connecting a first vacuum conduit to a vacuum source, wherein the vacuum conduit comprises a conduit and at least one individual gas line contained therein, and the exterior of the at least one individual gas line is exposed to less than atmospheric pressure; and connecting each of the at least one individual gas lines to a point of use while maintaining the exterior of each of the at least one individual gas lines under less than atmospheric pressure. 
     A system is disclosed for safely enabling the delivery of at least one individual gas line to at least one point of use in a facility which includes a first vacuum conduit, the first vacuum conduit comprising a conduit and at least one individual gas line contained therein, and a vacuum source connected to the vacuum conduit so that the exterior of each of the at least one individual gas lines is maintained under less than atmospheric pressure. 
     A vacuum sealed junction box is disclosed which includes a junction box coupled to a first vacuum conduit and to a second vacuum conduit, wherein both the first and second vacuum conduits comprise a conduit and at least one individual gas line contained therein, wherein the conduits of the first and second vacuum conduits discontinue once inside the junction box, thereby exposing the at least one individual gas line, wherein each of the at least one individual gas lines splits once inside the junction box so that a first length of each of the at least one individual gas lines can connect to a point of use and a second length of each the at least one individual gas lines can become contained within the second vacuum conduit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated 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  illustrates a vacuum conduit having a plurality of individual gas lines housed therein according to an embodiment disclosed herein. 
         FIG. 2  illustrates a schematic of a vacuum gas delivery system within a facility according to an embodiment disclosed herein. 
         FIG. 3A  illustrates a top view of a junction box and gas panel exhaust duct of a gas delivery system according to an embodiment disclosed herein. 
         FIG. 3B  illustrates a side view of aspects of a vacuum gas delivery system according to an embodiment disclosed herein. 
         FIG. 4  is a schematic of a gas line of a vacuum gas delivery system according to an embodiment disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical applications or technical improvements over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein. 
     Embodiments disclosed herein use a vacuum source to cost-effectively and safely enable the delivery of at least one gas line contained within a vacuum conduit to at least one point of use. More specifically, embodiments disclosed herein include a vacuum gas delivery system. A vacuum gas delivery system includes a vacuum system and a gas delivery system wherein the gas delivery system is housed within the vacuum system. In an exemplary embodiment, a vacuum source is used to safely deliver the same one or more gas lines to each of one or more processing chambers within a FAB by maintaining a vacuum conduit that surrounds the individual gas lines at less than atmospheric pressure as the gas lines travel through the FAB or under the FAB floor. Embodiments allow the delivery of each gas to each chamber using a single feed gas line for each gas. A vacuum source can provide the same or better safety features as an exhausted enclosure, but the vacuum source can use a vacuum conduit with a much smaller diameter than the bulky exhaust ducts required by exhausted enclosures. By using a vacuum conduit to enclose the individual gas lines and using a single feed line for each gas, the embodiments disclosed herein reduce the number of individual gas lines that need to be run through a facility. As a result of the embodiments disclosed herein, the cost of running gas lines is greatly reduced, the loss of valuable work space due to the enlarged ducts of exhausted enclosures is eliminated, and the potential equipment down time associated with using all-welded systems is eliminated. Moreover, keeping the gas lines under vacuum protects the gas lines and allows the gas lines to have fittings for easy installation and repair. 
       FIG. 1  illustrates a vacuum conduit  100  having a plurality of individual gas lines  20  housed therein according to an embodiment disclosed herein. The vacuum conduit  100  is shown as a round conduit, but can be any shape. The vacuum conduit  100  can be, for example, a pipe, sealed tray, or sealed trough, but in any event, the vacuum conduit  100  is an enclosure that can house gas lines  20  and maintain reduced pressure. The vacuum conduit  100  may be made of a material that is substantially impermeable to air, such as metal or a non-flammable composite material. Exemplary metals that may be used include aluminum, steel, stainless steel, and alloys thereof. Exemplary non-flammable composite materials that may be used include metal composites, carbon fiber, glass fiber and other fibrous composites. The vacuum conduit  100  functions as a vacuum enclosure so that when a vacuum source is applied to vacuum conduit  100 , the volume within vacuum conduit  100  around the gas lines  20  is maintained at less than atmospheric pressure. 
     Each gas line  20  may carry a different gas or mixture of gases used in a FAB or other facility. Alternatively, some gases used in the FAB or other facility may be carried in more than one gas line  20 . The gas lines  20  may vary in diameter, length, and composition material. Although vacuum conduit  100  is illustrated as having  26  gas lines contained therein, vacuum conduit  100  can have a different number of gas lines. 
       FIG. 2  illustrates vacuum gas delivery system  200 , which generally includes a vacuum system and a gas delivery system wherein the gas delivery system is housed within the vacuum system. The vacuum system includes facility gas sources  290  coupled to vacuum conduit  250  and a vacuum source  270  connected on one end to process scrubber  280  and on another end to vacuum conduit  250 , which couples to a first junction box  210  and communicates the reduced pressure environment created by vacuum source  270  to a series of junction boxes  210 ,  220 ,  230 , and  240  and vacuum conduits  251 ,  252 , and  253 , wherein each vacuum conduit communicates the reduced pressure environment from one junction box to another junction box. 
     Vacuum source  270  may be a vacuum pump, such as a conventional roughing pump available in most facilities. The vacuum source reduces the pressure within the vacuum gas delivery system  200  to below atmospheric pressure. Vacuum conduit  250  sealingly couples the vacuum source  270  to a first junction box  210 . A junction box, as discussed in more detail below, is capable of holding a vacuum and contains gas lines  20  and gas fittings to enable delivery of gases to a chamber, for example, while also continuing to deliver gases to another junction box. The junction box is accessible to make the necessary connections on the gas lines  20 , but is maintained under less than atmospheric pressure during normal operation. One or more junction boxes may be coupled to vacuum conduit  250  between the facility gas sources  290  and the first junction box  210  so as to enable the gas lines  20  to be connected with fittings. 
     A vacuum conduit  251  couples the first junction box  210  to a second junction box  220 . A vacuum conduit  252  couples the second junction box  220  to a third junction box  230 . A vacuum conduit  253  couples the third junction box  230  to a fourth junction box  240 . Since each junction box and each vacuum conduit are capable of holding a vacuum, the vacuum source  270  can maintain the entire system of junction boxes and vacuum conduits at less than atmospheric pressure. 
     Process scrubber  280  may be coupled to vacuum source  270  through a process scrubber conduit  275 . A process scrubber can scrub any hazardous gases that enter the vacuum source  270 , thereby enabling proper disposal or recycle of the exhausted gases. 
     Safety switch  260  may be connected to the vacuum system, such as at vacuum conduit  250 . While the vacuum system is running, a certain reduced pressure is maintained within the system. Safety switch  260  contains a pressure sensor, and if the sensor detects an increase in pressure, the switch will determine that a gas leak is present. For example, safety switch  260  could be a ½ atm pressure switch. The safety switch  260  is configured to communicate with the facility gas sources  290 . If the safety switch detects an increase in pressure, the safety switch will send a signal to the facility gas sources  290  ordering the facility gas sources  290  to be turned off. 
     The facility gas sources  290  include a plurality of access points for the various gases used within the FAB or other facility. Facility gas sources  290  may share a housing with vacuum source  270 . Vacuum conduit  250  sealingly couples to the facility gas sources  290 . Gas lines  20  contained within vacuum conduit  250  connect on one end to the access points of the facility gas sources  290  and may connect on the other end to gas panels associated with junction boxes  210 ,  220 ,  230 , and  240 . The gas lines  20  between the gas sources and the junction boxes may have a larger diameter than the gas lines connected between the junction boxes and the gas panels. As shown, the facility gas sources  290  are housed within the same housing as vacuum source  270 , but the facility gas sources  290  may be located elsewhere in the facility. 
     Junction boxes  210 ,  220 ,  230 , and  240  are vacuum sealed boxes wherein gas lines  20  may be split so that one gas line  20  may travel to a point of use associated with that individual junction box and another gas line  20  may travel to another junction box, to the facility gas sources  290 , or to another location. In some instances, the gas line may not need to be split within a junction box, such as if the junction box is the last junction box in a chain of junction boxes or a particular gas is not needed at other junction boxes. Each junction box may be connected to a point of use, such as a gas panel serving a process chamber. A junction box serves to link a series of points of use to the same gas lines  20  while maintaining the gas lines  20  safely under vacuum. 
     In the representative example shown in  FIG. 2 , the vacuum conduit  250  sealingly couples to a point of access to the facility gas sources  290 , and the point of access to facility gas sources  290  is coupled to at least some of the gas lines contained within vacuum conduit  250 . Vacuum conduit  250  also sealingly couples to first junction box  210 . Once inside first junction box  210 , the gas lines may be split so that one gas line may travel towards a point of use, such as to a gas panel serving a processing chamber, and a second gas line may enter vacuum conduit  251 . Vacuum conduit  251  sealingly couples on one end to first junction box  210  and on another end to second junction box  220 . Once inside second junction box  220 , the gas lines may split so that one gas line may travel towards a point of use, such as to a gas panel serving a second processing chamber, and a second gas line may enter vacuum conduit  252 . Vacuum conduit  252  sealingly couples on one end to second junction box  220  and on another end to a third junction box  230 . Once inside third junction box  230 , each gas line may split so that one gas line may travel towards a point of use, such as to a gas panel serving a third processing chamber, and a second gas line may enter vacuum conduit  253 . Vacuum conduit  253  may sealingly couple on one end to third junction box  230  and sealingly couple on another end to fourth junction box  240 . Once inside fourth junction box  240 , each gas line may travel towards a gas panel associated with a point of use, such as to a fourth processing chamber. Vacuum gas delivery system  200  is illustrated using four junction boxes, however, systems can be created that use a different number of junction boxes and points of use, e.g., gas panels serving processing chambers. 
       FIG. 3A  is a top view of a junction box  370  and gas panel exhaust duct  380  within a FAB. A first vacuum conduit  310  sealingly couples with junction box  370  wherein gas lines  311 ,  312 ,  313 , and  314  split so that one gas line can travel through a welded bulkhead  375  and into a gas panel exhaust duct  380  and a second gas line may travel into a second vacuum conduit  310 ,′ which is also sealingly coupled to junction box  370 . 
     Once inside junction box  370 , gas lines  311 ,  312 ,  313 , and  314  may connect to a first fitting, shown as  321 ,  322 ,  323 , and  324 . The first fitting may be a metal fitting, such as a metal union fitting. Conventional fittings are available from Swagelok, e.g., VCR fittings. Gas lines  311 ,  312 ,  313 , and  314  may connect to a splitter, shown as  331 ,  332 ,  333 , and  334 , located along each gas line. A first gas line from each of gas lines  311 ,  312 ,  313 , and  314  that leaves the splitters  331 ,  332 ,  333 , and  334 , respectively, may travel towards gas panel exhaust duct  380 . A second fitting, shown as  341 ,  342 ,  343 , and  344 , may be coupled to each gas line that travels towards the gas panel exhaust duct  380 . The second fitting may be a metal union fitting, with or without an integrated flow restrictor. The second fitting may connect to each gas line before the gas line reaches the welded bulkhead  375 . The first gas line may travel through the welded bulkhead  375  and into gas panel exhaust duct  380 . The welded bulkhead  375  forms a vacuum-tight connection between the junction box  370  and the gas panel exhaust duct  380 . Once the first gas line is within gas panel exhaust duct  380 , each gas line may connect with a fitting, shown as  351 ,  352 ,  353 , and  354 , that may connect each gas line to the gas panel associated with junction box  370 . The gas panel may be the point of use of each gas line and may serve a processing chamber. 
     A second gas line that leaves each splitter ( 331 ,  332 ,  333 , and  334 ) may extend towards second vacuum conduit  310 ′. Each gas line may couple to a third fitting (shown as  361 ,  362 ,  363 , and  364 ). The third fitting may be a metal fitting, such as a metal union fitting. Each gas line may then travel into the second vacuum conduit  310 ′ and exit junction box  370 . 
     Although first vacuum conduit  310  and second vacuum conduit  310 ′ are depicted as containing four gas lines, first vacuum conduit  310  and second vacuum conduit  310 ′ can contain a different number of gas lines. Each gas line that enters junction box  370  through first vacuum conduit  310  may exit the junction box  370  through second vacuum conduit  310 ′. Alternatively, some gas lines that enter junction box  370  through first vacuum conduit  310  may terminate in junction box  370 . 
       FIG. 3B  is a side view of the vacuum gas delivery system  200  connected to a chamber system within a FAB. As shown,  FIG. 3B  depicts vacuum conduit  310 , junction box  370 , individual gas lines  311 ,  312 , and  313 , a gas panel exhaust duct  380 , and a gas panel  390 . Vacuum conduit  310  sealingly couples to junction box  370 . Gas lines  311 ,  312 , and  313  exit junction box  370 , enter gas panel exhaust duct  380 , and then extend across welded bulkhead  376  and into gas panel  390 . While not shown, gas lines  311 ,  312 , and  313  can continue to other junction boxes downstream or upstream of the junction box shown. The vacuum gas delivery system may be located below the floor  301  of a facility, such as a FAB. Alternatively, vacuum gas delivery system may be located above the processing equipment. 
       FIG. 4  is a schematic of a single gas line within vacuum gas delivery system  200 , according to an embodiment disclosed herein. Single gas line  401  is contained within vacuum gas delivery system  200  and is connected on one end to a facility gas source  460  and is also connected to points of use  410 ,  420 ,  430 , and  440 . When vacuum gas delivery system  200  is running, the exterior of gas line  401  is exposed to less than atmospheric pressure. The points of use for single gas line  401  can be gas panels that serve processing chambers. Intersections  451 ,  452 ,  453 , and  454  indicate points along vacuum gas delivery system  200  where gas line  401  is within a junction box. 
     Embodiments disclosed herein include a vacuum gas delivery system. A vacuum gas delivery system includes a vacuum system and a gas delivery system wherein the gas system is housed within the vacuum system. In an exemplary embodiment, a vacuum source is used to safely deliver the same twenty or more gas lines to each of four or more processing chambers within a FAB by maintaining a conduit that surrounds the gas lines at less than atmospheric pressure as the gas lines travel through the FAB or under the FAB floor. A vacuum source can provide the same or better safety features as an exhausted enclosure, but the vacuum source can use a vacuum conduit with a much smaller diameter than the bulky exhaust ducts required by exhausted enclosures. 
     By using a vacuum source connected to a vacuum system enclosing individual gas lines, the embodiments disclosed herein reduce the number of individual gas lines that need to be run through a facility. As a result of the embodiments disclosed herein, the cost of running gas lines is greatly reduced, the loss of valuable work space due to the enlarged ducts of exhausted enclosures is eliminated, and the potential equipment down time associated with using all-welded systems is also eliminated. Moreover, keeping the gas lines under vacuum protects the gas lines and allows the gas lines to have fittings for easy installation and repair. 
     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, and the scope thereof is determined by the claims that follow.