Abstract:
A transport system for conveying articles along conveyance paths including straight, curvilinear, horizontal, vertical, inclined, and declined conveyance sections optionally physically offset from one another horizontally, vertically, or combinations thereof. The articles are conveyed between a pair of transport belts or rollers and/or by conveyance elements such as a gripper, a robotic hoist, a lift, or an elevator while being optionally supported by protrusions extending from the belts or rollers, secured via a kinematic interface, grasped by a gripper, or supported by air bearings. Multiple conveyance sections, lifts, robotic hoists, grippers, and elevators can be joined, interfaced, and/or integrated over complex paths and arrangements with one another as well as with manufacturing, processing, measurement, and sorting equipment. The articles conveyed may include semiconductor wafers, substrates for the manufacture of display devices or photovoltaics, or the like.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/840,131 entitled “High Speed Transfers Between Transport Devices” and filed on Aug. 25, 2006, which is incorporated by reference herein. This application is related to U.S. application Ser. No. 11/406,569 entitled “Transport System Including Vertical Rollers” and filed on Apr. 18, 2006; U.S. application Ser. No. 11/764,161 entitled “Transport System Including Vertical Rollers” and filed on Jun. 15, 2007; U.S. application Ser. No. 11/764,755 entitled “Conveyor System Including Offset Section” and filed on Jun. 18, 2007; and U.S. application Ser. No. 11/818,657 entitled “Systems and Methods for Transport Through Curves” and filed on Jun. 14, 2007. The disclosures of each of the aforementioned applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The current invention relates to transport systems and methods for conveying articles along a conveyance path, and in some embodiments to conveying semiconductor wafers in a semiconductor fabrication facility.  
         [0004]     2. Related Art  
         [0005]     Transport systems are widely employed in industrial manufacturing facilities to convey articles between work stations. Originally, these systems were manual and workers moved articles by hand or by cart. Modern factories have developed specialized equipment to convey articles automatically. In particular, semiconductor fabrication facilities currently use automated transport systems to move semiconductor wafers during the manufacturing process. Typically, a batch of wafers may be conveyed together in a container known as a Front Opening Unified Pod (FOUP). Semiconductor wafer manufacturers have sought to increase manufacturing productivity by using transport systems that efficiently convey wafers from machine to machine without exposing the wafers to excessive contamination, to excessive vibration, or to excessive acceleration and deceleration forces.  
         [0006]     Existing transport systems employ vehicle-based devices to grasp a FOUP using a top handle and move the FOUP from one location to another location. For example, a vehicle may be used to grasp a FOUP, raise the FOUP to a higher level, move the FOUP to a new position above a destination, lower the FOUP onto the destination, and then release the FOUP. After the vehicle has released the FOUP, the vehicle may then be dispatched to a location of a next FOUP requiring similar movement. While the vehicle is transporting the FOUP, the vehicle is considered loaded. After the vehicle has released the FOUP and before the vehicle grasps the next FOUP, it is considered empty. A period of time during which the vehicle is empty, for example the period of time during which the empty vehicle moves from the location where the vehicle released the first FOUP to the location where the vehicle grasps the next FOUP, increases the overall time required for delivery of FOUPs to their destinations. The period of time the vehicle is empty may lead to a bottleneck and cause traffic congestion in a fabrication facility due to an inefficient use of resources.  
         [0007]     There are, therefore, needs for improved systems and methods for conveying in manufacturing facilities.  
       SUMMARY OF THE INVENTION  
       [0008]     In a semiconductor fabrication facility, it is desirable to transport material at very high speeds throughout the fabrication facility and then quickly deliver the material onto process and metrology equipment. The material is typically transported inside a carrier called a FOUP. The FOUP can be transported on a transport system such as those disclosed in U.S. patent application Ser. Nos. 11/406,569, 11/764,161, 11/764,755, and 11/818,657. In these applications, systems are disclosed that can move a FOUP at speeds higher than systems of the prior art. The FOUP is typically supported by a moving transport belt from below the FOUP.  
         [0009]     The present invention includes, in various embodiments, a transport system for transferring articles that are moving along a conveyance path from one source location, conveyance section, processing tool, storage location, or the like to a destination location, conveyance section, processing tool, storage location, or the like. The articles may be moved in any combination of directions in three dimensions, including up, down, north, south, east, or west. The conveyance path along which the article is transported may include straight, curvilinear, horizontal, inclined and/or declined sections.  
         [0010]     The present invention includes, in various embodiments, a system comprising a first conveyance section comprising a first transport belt and a second transport belt disposed on either side of a conveyance path. The first conveyance section is configured to convey a FOUP along the conveyance path. The first transport belt and the second transport belt are separated by a distance configured for placement of the FOUP between the first transport belt and the second transport belt. Further, the system includes a lift configured to lift the FOUP from the first transport belt and the second transport belt. The lift is further configured to rotate the FOUP such that the FOUP can pass between the first transport belt and the second transport belt along a vertical axis.  
         [0011]     The present invention includes, in various embodiments, a system comprising a first conveyance section including a first transport belt and a second transport belt disposed on either side of a conveyance path. The first conveyance section is configured to convey a FOUP along the conveyance path. The first transport belt and the second transport belt are separated by a distance configured for placement of the FOUP between the first transport belt and the second transport belt. The first conveyance section is disposed at a first height. Additionally, the system comprises an elevator including a first elevator belt and a second elevator belt. The elevator is configured to lift the FOUP from the first conveyance section. The elevator is further configured move the FOUP to a second conveyance section at a second height.  
         [0012]     The present invention includes, in various embodiments, a system comprising a first conveyance section including a first transport belt and a second transport belt disposed on either side of a conveyance path. The first conveyance section is configured to convey a FOUP along the conveyance path. The first transport belt and the second transport belt are separated by a distance configured for placement of the FOUP between the first transport belt and the second transport belt. The first conveyance section is disposed at a first height. Furthermore, the system comprises an overhead gripper including a first gripper belt and a second gripper belt. The first gripper belt and the second gripper belt are configured to grip a top handle of the FOUP. The overhead gripper is further configured to raise the FOUP from the first height to a second height.  
         [0013]     The present invention includes, in various embodiments, a system comprising a turntable. The turntable includes a first transport belt and a second transport belt disposed on either side of a conveyance path. The first transport belt and the second transport belt are separated by a distance configured for placement of the FOUP between the first transport belt and the second transport belt. The turntable is configured to receive a FOUP from a first location at a first angle relative to a central vertical axis between the first transport belt and the second transport belt. The turntable is further configured to convey the FOUP along the conveyance path, rotate the FOUP about the vertical axis, and deliver the FOUP to a second location at a second angle relative to the central vertical axis.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     For a more complete understanding of the present invention and for further features and advantages, reference is made to the following description taken in conjunction with the accompanying drawings, in which:  
         [0015]      FIG. 1  is a perspective view of a conveyance section according to various embodiments of the invention;  
         [0016]      FIG. 2A  illustrates a conveyance section comprising a lift including a kinematic interface, according to various embodiments of the invention;  
         [0017]      FIG. 2B  illustrates the conveyance section in which the lift rotates a FOUP in a direction of rotation;  
         [0018]      FIG. 2C  illustrates the conveyance section  200  after the lift has rotated the FOUP by approximately 90 degrees;  
         [0019]      FIG. 3  illustrates a top view of a FOUP indicating typical dimensions, according to various embodiments of the invention;  
         [0020]      FIG. 4  Illustrates a method of using the lift as shown in  FIGS. 2A, 2B , and  2 C to lower the FOUP from the conveyance section to another location, according to various embodiments of the invention;  
         [0021]      FIGS. 5A, 5B ,  5 C, and  5 D illustrate a side view of the conveyance sections shown in  FIGS. 2A, 2B , and  2 C at various steps of the method illustrated in  FIG. 4 , according to various embodiments of the invention;  
         [0022]      FIGS. 6A and 6B  illustrate a transfer system comprising a conveyance section, a robotic hoist, and machine load ports, according to various embodiments of the invention;  
         [0023]      FIGS. 7A, 7B ,  7 C,  7 D, and  7 E illustrate cross-sectional views of a transfer system comprising two conveyance sections, rotatable rails, a lift, and a FOUP in different states of transfer, according to various embodiments of the invention;  
         [0024]      FIG. 8  illustrates a transport section comprising a conveyance section and an overhead gripper system, according to various embodiments of the invention;  
         [0025]      FIG. 9  illustrates a transport section comprising a conveyance section in conjunction with overhead gripper belts, according to various embodiments of the invention;  
         [0026]      FIG. 10  illustrates a transport system comprising an overhead gripper ramp in conjunction with a conveyance section, according to various embodiments of the invention;  
         [0027]      FIG. 11  illustrates a profile view of the gripper belts, according to various embodiments of the invention;  
         [0028]      FIGS. 12A and 12B  illustrate a transport system comprising several conveyance sections and a turnstile, according to various embodiments of the invention;  
         [0029]      FIG. 13  illustrates a method of using the transport system illustrated in  FIGS. 12A and 12B  to transfer a FOUP to and from a machine load port, according to various embodiments of the invention;  
         [0030]      FIG. 14  illustrates a vertical conveyance section or elevator, according to various embodiments of the invention;  
         [0031]      FIG. 15  illustrates a transport system comprising several conveyance sections and an elevator as illustrated in  FIG. 14 ;  
         [0032]      FIG. 16  illustrates a method of transferring an article in a vertical direction using the elevator as illustrated in  FIGS. 14 and 15 ;  
         [0033]      FIG. 17  illustrates a transport section comprising a first transport belt  110  and a second transport belt  120 , the transport section being configured to provide air bearings along a conveyance path between the first transport belt  110  and the second transport belt  120 ; and  
         [0034]      FIGS. 18A, 18B , and  18 C illustrate air bearing generators configured to generate the air bearings illustrated in  FIG. 17 .  
         [0035]      FIG. 19  shows a bottom view of a FOUP including valves for purging the interior thereof.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]      FIG. 1  is a perspective view of a conveyance section  100  according to various embodiments of the invention. The conveyance section  100  comprises a first transport belt  110 , a second transport belt  120 , a plurality of rollers  150 , and optional support protrusions  130 . The plurality of rollers  150  are configured to guide and optionally support the first transport belt  110  and the second transport belt  120 . The support protrusions are typically coupled with the first transport belt  110  and the second transport belt  120  and configured to support an article such as a FOUP  170 . In various embodiments, the first transport belt  110  and/or the second transport belt  120  may be vertically oriented, horizontally oriented, or slanted between horizontal and vertical. In some embodiments, at least some portion of the first transport belt  110  and/or the second transport belt  120  may be substituted with alternative support members such as rollers. In these embodiments, support protrusions may also optionally be coupled with the alternative support members and configured to support an article such as a FOUP  170 .  
         [0037]     The conveyance section  100  is configured to convey the FOUP  170  in a conveyance direction  180  along a conveyance path between the first transport belt  110  and the second transport belt  120 . The conveyance section  100  may be configured with multiple instances of conveyance sections  100 .  
         [0038]      FIG. 2A  illustrates a conveyance section  200  comprising a first transport belt  110 , a second transport belt  120 , a plurality of optional support protrusions  130 , and a lift  210 . In various embodiments, the conveyance section  200  may comprise any embodiment of the conveyance section  100  further comprising the lift  210 . The lift  210  is configured to include a kinematic interface, according to various embodiments of the invention. The lift  210  may be disposed between the transport belts  110  and  120  such that the lift  210  can be raised and lowered along a vertical axis  190  under the FOUP  170  when the FOUP  170  is disposed in a location above the lift  210 . In some embodiments, the lift  210  may be configured to raise the FOUP  170  above a horizontal plane of the transport belts  110  and  120  within the conveyance section  200 . In other embodiments, the lift  210  may be configured to lower the FOUP  170  below the horizontal plane of the transport belts  110  and  120  within the conveyance section  200 . In still other embodiments, the lift  210  may be configured to both raise and lower the FOUP  170  above and below the horizontal plane of the transport belts  110  and  120  within the conveyance section  200 .  
         [0039]      FIG. 2B  illustrates the conveyance section  200  in which the lift  210  rotates the FOUP  170  in a direction of rotation  230 . As the conveyance section  200  moves the FOUP  170  proximate to the lift  210 , the conveyance section optionally stops the FOUP  170  in a position approximately over the lift  210 . Interface features, such as kinematic coupling pins  215  disposed on a top surface of the lift  210 , may optionally interact and couple with corresponding interface features on a bottom surface of the FOUP  170 , such as three kinematic holes. The kinematic coupling pins  215  and related features are configured to support proper alignment between the FOUP  170  and the lift  210 . After the FOUP  170  is aligned and coupled with the lift  210 , the lift  210  may be used to lift the FOUP  170  above a surface of the transport belts  110  and  120  and/or support protrusions  130 . Once the FOUP  170  is above and no longer in substantial contact with the transport belts  110  and  120  and/or the support protrusions  130 , the lift  210  may rotate the FOUP  170  freely in a rotational direction  230  along a horizontal plane. In some embodiments, the lift  210  may rotate in a rotational direction opposite the rotational direction  230 . The lift  210  may rotate the FOUP  170  by approximately a positive or negative 90 degrees, 180 degrees, 270 degrees, or 360 degrees.  FIG. 2C  illustrates the conveyance section  200  after the lift  210  has rotated the FOUP  170  by approximately 90 degrees.  
         [0040]     As illustrated in  FIG. 3 , the FOUP  170  is characterized by a longer width  330  parallel to the FOUP door  310  relative to a length  320  perpendicular to the FOUP door  310 . For example, in various embodiments, the width  330  may be approximately 390 mm, and the length  320  may be approximately 356 mm. The spacing between transport belts  110  and  120  is typically configured to support the FOUP  170  when the FOUP  170  is oriented such that the width  330  and FOUP door  310  are perpendicular to the transport belts  110  and  120  along the horizontal axis  195 . Therefore, when the lift  210  rotates that FOUP  170  in approximately a multiple of ninety degrees, the smaller FOUP length  320  will be perpendicular to the transport belts  110  and  120  along the horizontal axis  195 . When the FOUP  170  is oriented in this manner, the conveyance section  200  is configured to provide a clearance  240  ( FIG. 2C ) between the FOUP  170  and the support protrusions  130  of the transport belts  110  and  120 . The clearance  240  enables the lift  210  to lower the FOUP  170  down between the transport belts  110  and  120  without contacting the transport belts  110  and  120  or the support protrusions  130 . The lift  210  may be configured to lower the FOUP  170  below the horizontal plane of the transport belts  110  and  120  by any amount as needed to deliver the FOUP  170  to its next destination. Once the FOUP  170  has been lowered below the horizontal plane of the transport belts  110  and  120 , the FOUP  170  may be rotated by any arbitrary amount as appropriate or necessary to align the FOUP  170  with another conveyance section  200  or other destination, or held in place.  
         [0041]     Because the clearance  240  is not required for the lift  210  to raise the FOUP  170  above a horizontal plane of the transport belts  110  and  120 , the lift  210  is not required to rotate the FOUP  170  before raising the FOUP  170  along the vertical axis  190 . Furthermore, the lift  210  may rotate the FOUP  170  by any arbitrary amount before, during, or after raising the FOUP  170  along the vertical axis  190  as appropriate or necessary to align the FOUP  170  with another conveyance section  200  or other destination.  
         [0042]     In various embodiments, specific mechanical, electrical, and software interfaces are defined to enable a variety of devices to directly access the FOUP  170  disposed on the transport belts  110  and  120 . Embodiments of such interfaces include a mechanical interface such as the kinematic interface defined by the trade organization SEMI in the document number E57-0600 entitled “Mechanical Specification for Kinematic Couplings used to Align and Support 300 mm Wafer Carriers” and the electrical interface and software communications interface defined by the SEMI standard E84-0305 entitled “Specification for Enhanced Carrier Handoff Parallel I/O Interface.” The kinematic interface features three kinematic coupling pins on a kinematic mount, the kinematic coupling pins being configured to mate with three corresponding depressions disposed on the bottom of the FOUP  170  when the FOUP  170  is placed in proper alignment with the kinematic mount.  
         [0043]      FIG. 4  illustrates a method of using the lift  210  as shown in  FIGS. 2A, 2B , and  2 C to lower the FOUP  170  from the conveyance section  200  to another location, according to various embodiments of the invention. The method may be implemented using a combination of computer systems comprising both hardware and software coupled with the conveyance section  200 . The method is employed when a FOUP  170  is supported by a pair of transport belts  110  and  120  above a lift  210 .  
         [0044]     In step  401 , a command to transport FOUP  170  to a destination is received. The command may be first determined and transmitted by a computer system and/or operator configured to control the movement of FOUPs  170  throughout a transport system comprising a plurality of conveyance sections  200  and other related transport devices. The destination is typically a location within the transport system, and may be proximate a lift  210  or a conveyance section  200 .  
         [0045]     In step  402 , a primary route between the current location of the FOUP  170  and the destination is determined.  
         [0046]     In step  403 , a determination is made regarding whether the destination is below the transport belts  110  and  120 . If the destination is determined to not be below the transport belts  110  and  120 , the method ends at a step  404 , and the lift  210  is not utilized. If the destination is determined to be below the transport belts  110  and  120  in step  403 , then step  405  is performed.  
         [0047]     In step  405 , the transport belts  110  and  120  are used to convey the FOUP  170  along the route to the lift  210  as illustrated in  FIG. 1 . Step  405  ends when the FOUP  170  is located directly above the lift  210 , at which time step  406  is executed.  
         [0048]     In step  406 , the lift  210  is raised to couple with the FOUP  170 . After step  406  is completed, step  407  may optionally be performed.  
         [0049]     In optional step  407 , an output of a sensor disposed on lift  210  is read in order to assure that FOUP  170  is properly coupled with lift  210 .  
         [0050]     In optional step  408 , the output of the sensor-read in step  407  is evaluated to determine whether the FOUP  170  is properly coupled with the kinematic coupling pins  215  on the lift  210 . If the evaluation indicates that the FOUP  170  is not properly coupled with the lift  210 , then step  409  is performed. Otherwise, step  411  is performed.  
         [0051]     In optional step  409 , an error is reported. Following the reporting of the error, the method is stopped at step  410 .  
         [0052]     In step  411 , the lift  210  rotates the FOUP  170  by approximately a multiple of 90 degrees.  
         [0053]     In step  412 , the lift  210  lowers the FOUP  170  along a vertical axis  190  to a destination level of the intended destination. At the conclusions of step  412 , the method ends at step  413 .  
         [0054]      FIGS. 5A, 5B ,  5 C, and  5 D illustrate a side view of the conveyance sections  200  shown in  FIGS. 2A, 2B , and  2 C at various steps of the method illustrated in  FIG. 4 , according to various embodiments of the invention. In these embodiments, the lift  210  lowers the FOUP  170  along a vertical axis  190  from a first set of transport belts  110 A and  120 A to a second set of transport belts  110 B and  120 B. The second set of transport belts  111 B and  120 B may be configured to transport the FOUP  170  in any desired direction. As illustrated in  FIGS. 5A, 5B ,  5 C, and  5 D, the second set of transport belts  110 B and  120 B are configured to transport the FOUP  170  in a direction approximately 90 degrees from the conveyance direction  180  of the first set of transport belts  110 A and  120 A. Using the lift  210 , an intersection  510  between the first set of transport belts  110 A and  120 A and the second set of transport belts  110 B and  120 B can be created without physically interfering or modifying either the first set of transport belts  110 A and  120 A and the second set of transport belts  110 B and  120 B. Therefore, neither the first set of transport belts  110 A and  120 A nor the second set of transport belts  110 B and  120 B need to begin or end a conveyance section  200  at any specific point. The intersection  510  may be located anywhere along a length of a conveyance section  200 , such as towards the middle or near either end. Flexibility in placement of the intersection  510  along a conveyance section  200  allows conveyance sections  200  to be deployed and relocated without being configured as having specific lengths.  
         [0055]     As illustrated in  FIG. 5A , the FOUP  170  is conveyed along transport belts  110 A and  120 A toward the intersection  510 . As illustrated in  FIG. 5B , the FOUP  170  is disposed at the intersection  510  where the lift  210  is configured to move along a vertical axis  190  between the first set of transport belts  110 A and  120 A and the second set of transport belts  110 B and  120 B. The lift  210  is used to lift the FOUP  170  from the first set of transport belts  110 A and  120 A. As illustrated in  FIG. 5C , the FOUP  170  is rotated approximately 90 degrees and the lift  210  lowers the FOUP  170  through a space between the first set of transport belts  110 A and  120 A. Once below a horizontal plane of the transport belts  110 A and  120 A, the lift  210  optionally rotates the FOUP  170  by an angle defined as the angle between the conveyance direction  180  of the first set of transport belts  110 A and  120 A and a conveyance direction of the second sets of transport belts  110 B and  120 B. Once properly oriented, the FOUP  170  may be lowered onto the second set of transport belts  110 B and  120 B as illustrated in  FIG. 5D . The second set of transport belts  110 B and  120 B may transport the FOUP  170  in a new conveyance direction.  
         [0056]      FIGS. 6A and 6B  illustrate a transfer system  600  comprising a conveyance section  200 , a robotic hoist  630 , and machine load ports  610 , according to various embodiments of the invention. After a conveyance section  200  conveys a FOUP  170  via transport belts  110  and  120  to an equipment transfer location  680  near the location of a destination process or metrology equipment  620 , the transfer system  600  may transfer the FOUP  170  onto the equipment for processing or metrology. In some embodiments, the conveyance section  200  comprising transport belts  110  and  120  may be disposed above the process or metrology equipment  620 . The lift  210  may lift the FOUP  170  from the transport belts  110  and  120 , rotate the FOUP  170 , and then lower the FOUP  170  to an intermediate location  660  as shown in  FIG. 6B . The destination processing or metrology equipment  620  may be configured to access the FOUP  170  while the FOUP  170  is located at the intermediate location  660 , open the FOUP front door  310 , and process or perform measurements of the contents such as semiconductor wafers disposed within the FOUP  170 .  
         [0057]     Alternatively, when the processing or metrology equipment  620  is ready to receive the FOUP  170 , the transfer system  600  may transfer the FOUP  170  from the intermediate location  660  onto an equipment load port  610  using a device such as a robotic hoist  630  comprising a gripper  640 . The robotic hoist  630  may be configured to use the gripper  640  to grasp a top handle disposed on a top surface of the FOUP  170 , lift the FOUP  170  from the lift  210  at the intermediate location  660 , move the gripper  640  horizontally until the gripper  640  is over the destination equipment load port  610 , lower the FOUP  170  along a vertical axis  190  until the FOUP  170  rests on or couples with the equipment load port  610 , and release the FOUP  170 .  
         [0058]     In various embodiments, the robotic hoist  630  is integrated with the conveyance section  200  comprising the transport belts  110  and  120 . Integration of the robotic hoist  630  with the conveyance section  200  reduces mis-alignment between the gripper  640 , the intermediate location  660 , and the load ports  610 . In addition, the robotic hoist  630  may be configured to share a common power and communications infrastructure as well as mechanical and seismic supports with the conveyance section  200 .  
         [0059]     In some embodiments, the lift  210  may be integrated with a load port of the processing or metrology equipment  620 . In these embodiments, the lift  210  may also be integrated with a load port FOUP front door opening device. Such integration between the equipment load port and the lift  210  of the transfer system  600  eliminates intermediate steps and mechanisms. The lift  210  integrated with the load port  610  may be configured to transfer the FOUP  170  directly from the transport belts  110  and  120  to a machine load port location  670  at a load port  610 . After the FOUP  170  is transferred to the machine load port location  670 , the equipment may open the FOUP door and access material such as semiconductor wafers located within the FOUP  170 .  
         [0060]     In various embodiments, the transfer system  600  is configured to transfer a FOUP  170  from the transport belts  110  and  120  to the processing or metrology equipment  620  without stopping the motion of the FOUP  170  on the transport belts  110  and  120 . The lift  210  with the kinematic interface may be configured with an additional axis of motion such that the lift  210  may be moved horizontally along the conveyance direction  180  in synchronization with the movement of the FOUP  170  along the transport belts  110  and  120  in the conveyance direction  180 . When the position along a vertical axis  190  and speed along the conveyance direction  180  of the kinematic lift  210  and the FOUP  170  is about equal, the lift  210  may be raised to couple with the FOUP  170 , lift the FOUP  170 , rotate the FOUP  170 , and lower the FOUP  170 . The kinematic lift  210  may then move the FOUP  170  in both horizontal and vertical directions to position the FOUP  170  at the destination load port  610 . The kinematic lift  210  that is configured to move along the horizontal conveyance direction  180  as well as raise and lower along a vertical axis  190  enables the transport belts  110  and  120  to maintain their full speed when the FOUP  170  is removed from or placed on the transport belts  110  and  120 . In some embodiments, the transport belts  110  and  120  may be slowed down when a FOUP  170  is loaded or unloaded to assure that no collision occurs between the FOUP  170  being loaded or unloaded from transport belts  110  and  120  and other FOUPs  170  being transported on the same transport belts  110  and  120 .  
         [0061]      FIGS. 7A, 7B ,  7 C,  7 D, and  7 E illustrate cross-sectional views of a transfer system  700  comprising two conveyance sections  200 , rotatable rails  710  and  720 , a lift  210 , and a FOUP  170  in different states of transfer, according to various embodiments of the invention. In some embodiments, additional clearance is required to lower the FOUP  170  between the transport belts  110 A and  120 A. In these embodiments, the transport belts  110 A and  120 A are optionally mounted on rotatable rails  710  and  720 , respectively, so that the transport belts  110 A and  120 A can be rotated about an axis at the outside of their lateral dimension, such as axes  715  and  725 , respectively. As illustrated in  FIG. 7A , the FOUP  170  is supported by the transport belts  110 A and  120 A at an intersection  510  above a lift  210 . As illustrated in  FIG. 7B , the lift  210  lifts the FOUP  170  from the transport belts  110 A and  120 A. As illustrated in  FIG. 7C , the rotatable rail  710  coupled with the transport belt  110 A is rotated away from the FOUP  170  about the axis  715  in a direction of rotation  730  and the rotatable rail  725  coupled with the transport belt  120 A is rotated away from the FOUP  170  about the axis  725  in a direction of rotation  740  such that the support protrusions  130  are no longer oriented along a horizontal axis in the horizontal plane of the conveyance section  200 . The rotation of the rotatable rails increases the open space between the transport belts  110 A and  120 A. As illustrated in  FIG. 7D , using this additional space, the lift  210  can lower the FOUP  170  from above the transport belts  110 A and  120 A, through the open space between them down to another conveyance section  200  comprising transport belts  110 B and  120 B. The additional open space between the transport belts  110 A and  120 A provided by the rotatable rails  710  and  720  decreases the possibility of interference between the FOUP  170  and the transport belts  110 A and  120 A. As illustrated in  FIG. 7E , after the lift  210  has lowered the FOUP  170  from the transport belts  110 A and  120 A to the transport belts  110 B and  120 B, the rotatable rails  710  and  720  are rotated back to their original positions as previously illustrated in  FIGS. 7A and 7B . In an alternative embodiment, rather than using rotatable rails, the conveyance section  200  may be configured to shift the horizontal position of the transport belts  110 A and  120 A along the horizontal axis  195  away from another, by a sufficient amount, such as a few centimeters, to allow sufficient clearance for the lift  210  to lower the FOUP  170  through the space between the transport belt  110 A and the transport belt  120 A.  
         [0062]      FIG. 8  illustrates a transport section  800  comprising a conveyance section  100  and an overhead gripper system  830 , according to various embodiments of the invention. The conveyance section  100 , further comprising transport belts  110  and  120 , is configured to convey a FOUP  170  along a conveyance direction  180  below the overhead gripper system  830 . The overhead gripper system  830  is configured to support and move an overhead gripper  810  in a horizontal direction along the conveyance direction  180  in parallel with the conveyance direction  180  of the conveyance section  100 . The gripper  810  may be configured to allow some flexibility and increase reliability of the FOUP  170  transfer. For example, the gripper  810  may be configured to include a simple device with fingers, such as gripper fingers  840 , to actively grasp the FOUP  170  top handle such as is commonly used by hoists to handle FOUPs in a production environment. This grasping action can occur while FOUP  170  is moving along transport belts  110  and  120 .  
         [0063]     The overhead gripper system  830  is configured to lower the gripper  810  toward the FOUP  170 , grasp a top handle of the FOUP  170  using gripper fingers  840 , and lift the FOUP  170  off the transport belts  110  and  120 . The gripper system  830  may be configured to grasp and lift the FOUP  170  as it travels along the conveyance direction  180  on the transport belts  110  and  120  without requiring the transport belts  110  and  120  to slow down or stop. The gripper system  830  may cause the speed of the gripper  810  along the conveyance direction  180  to match the speed of the FOUP  170  on the transport belts  110  and  120  along the conveyance direction  180 . When the speed is matched, the gripper  810  is lowered into place on the top handle of the FOUP  170  until the gripper fingers  840  can grasp the FOUP  170 . Once the FOUP  170  is securely held by the gripper fingers  840 , the gripper  810  may lift the FOUP  170  from the transport belts  110  and  120  and transfer the FOUP  170  to a variety of locations such as a buffer location, an equipment load port, or another section of transport belt in another location, altitude, or orientation. In some embodiments, the transport belts  110  and  120  may be significantly slowed or stopped prior to the gripper system  830  positioning the gripper  810  above the FOUP  170 , lowering the gripper  810  onto the top handle of the FOUP  170 , grasping the FOUP  170  using the gripper fingers  840 , and lifting the FOUP  170  off the transport belts  110  and  120 .  
         [0064]      FIG. 9  illustrates a top profile of a transport section  900  comprising a conveyance section  100  in conjunction with overhead gripper belts  930  and  940 , according to various embodiments of the invention. In these embodiments, an overhead gripper system  910  comprises a pair of gripper belts  930  and  940  with features designed to engage a top handle  690  of the FOUP  170 . The gripper belts  930  and  940  may be substantially vertical belts, horizontal belts, or slanted belts oriented between horizontally and vertically. As illustrated in  FIG. 9 , the transport belts  110  and  120  are conveying the FOUP  170  in a conveyance direction  180  while being supported by support protrusions  130 . Two gripper belts  930  and  940  may be positioned line with the top handle  690  of the FOUP  170 . The speed of the transport belts  110  and  120  and the gripper belts  930  and  940  may be sufficiently matched such that the gripper belts  930  and  940  may engage the top handle  690  of the FOUP  170  without significant relative motion between the top handle  690  of the FOUP  170  and the gripper belts  930  and  940 . Alternatively, the gripper belts  930  and  940  may be configured to reduce relative motion between the top handle  690  of the FOUP  170  and the gripper belts  930  and  940  by enabling a servo-motor or gear coupled with the gripper belts  930  and  940  to be released from active driving and allow the gripper belts  930  and  940  to move freely with the motion of the FOUP  170 . Once the gripper belts  930  and  940  fully engage the FOUP  170 , the gripper system  910  may lift the FOUP  170  and remove the FOUP  170  from the original transport belts  110  and  120 . Once lifted from the transport belts  110  and  120 , the gripper system  910  may stop and/or move the FOUP  170  to an alternative location such as a buffer, transport rail, or process equipment load port.  
         [0065]      FIG. 10  illustrates a transport system  1000  comprising an overhead ramped gripper  1010  in conjunction with a conveyance section  100 , according to various embodiments of the invention. In some embodiments, the gripper belts  930  and  940 , as illustrated in  FIG. 10 , are constructed with a ramp feature. In these embodiments, the overhead ramped gripper  1010  grasps the FOUP  170  and lifts the FOUP  170  from the surface of the transport belts  110  and  120  using the gripper belts  930  and  940 , and then moves the FOUP  170  upwards along a gripper belt ramp  1020 . The overhead ramped gripper system  1010  is configured such that a conveyance path of the gripper belts  930  and  940  follows a shape of the gripper ramp  1020  without separate mechanism to move the gripper belts  930  and  940 . Once the ramped gripper system  1010  moves the FOUP  170  above the transport belts  110  and  120 , the ramped gripper system  1010  may stop movement of the FOUP  170  and hold the FOUP  170  in buffer as needed. Alternatively, the ramped gripper belt system  1010  may be curved rather than piece-wise linear as illustrated in  FIG. 10 . In other embodiments, the ramped gripper belt system  1010  may be curved in a horizontal axis  195  out of vertical alignment with the conveyance section  100 . In still other embodiments, the ramped gripper belt system  1010  may be moved along a combination of a vertical axis  190 , a horizontal axis  195 , and/or a conveyance direction axis  180  using external motors to move the FOUP  170  and lower the FOUP  170  onto a different location, such as a different set of transport belts  110  and  120 .  
         [0066]      FIG. 11  illustrates a profile view of the gripper belts  930  and  940 , according to various embodiments of the invention. In these embodiments, the gripper belts  930  and  940  are moved around pulleys  1110  and  1120 , respectively, to match a speed of transport belts  110  and  120  as they transport the FOUP  170  along a conveyance direction  180 .  
         [0067]      FIGS. 12A and 12B  illustrate a transport system  1200  comprising several conveyance sections  100  and a turntable  1220 , according to various embodiments of the invention. When transport belts such as transport belts  110  and  120  transport the FOUP  170 , the FOUP  170  may be removed from the transport belts  110  and  120  to be placed on an equipment load port  1250 . In some embodiments, the FOUP  170  is engaged to a load port  1250  specially configured to have a low complexity mechanism with a small delay in operations involving the FOUP  170 . As illustrated in  FIG. 12A , the transport belts  110  and  120  convey the FOUP  170  along a conveyance direction  180  toward a turntable  1220 . The FOUP  170  is conveyed onto the turntable  1220 . The turntable belts  1260  and  1270  may be configured to be stationary when the turntable  1220  rotates. Alternatively, the turntable belts  1260  and  1270  may be configured to move as the turntable  1220  rotates. The turntable belts  1260  and  1270  may be configured to match a speed of the transport belts  110  and  120  when the transport belts  110  and  120  convey the FOUP  170  onto the turntable belts  1260  and  1270 . The turntable  1220  is configured to rotate about a central axis of rotation  1225  (perpendicular to the plane of the drawing) to change the direction of travel of the FOUP  170 . The turntable belts  1260  and  1270  may be configured to significantly slow or stop motion of the FOUP  170  while the turntable  1220  rotates to change the direction of travel of the FOUP  170 .  
         [0068]     The turntable  1220  may rotate the FOUP  170  by, for example, approximately ninety degrees, to orient the turntable belts  1260  and  1270  such that the turntable belts  1260  and  1270  are in approximate alignment with destination transport belts such as the transport belts  1230  and  1240 . Using the turntable belts  1260  and  1270 , the turntable  1220  can move the FOUP  170  onto the transport belts  1230  and  1240 . The transport belts  1230  and  1240  are configured to guide the FOUP  170  from the turntable  1220  directly to a specially configured load port  1250  of a process or metrology equipment or wafer sorting device, as illustrated in  FIG. 12B . The load port  1250  may be configured to utilize a kinematic interface to clamp the FOUP  170  in place between the transport belts  1230  and  1240  from below. By clamping the FOUP  170  in place, the FOUP  170  may not move during processing. In various embodiments, the FOUP door  310  is pressed against the load port  1250  of the equipment such that the load port  1250  can open or remove the FOUP door  310  and the equipment can access the materials such as semiconductor wafers stored within the FOUP  170 .  
         [0069]     Once the process, metrology or sorting equipment has completed its task using the materials stored within the FOUP  170 , the FOUP door  310  can be closed or replaced. The load port  1250  may now release the latch holding the FOUP  170  in place if needed. The transport belts  1230  and  1240  may thereafter move the FOUP  170  backwards to the turntable  1220 . The turntable  1220  may then rotate the FOUP  170  to orient the FOUP  170  to travel on a selected pair of transport belts  110  and  120  to a next destination. Typically, the transport system  1200  is mounted at approximately the industry standardized load port height of 900 mm, or alternatively additional load ports  1250  may be provided on the process, metrology, or sorting equipment at a height of the installed transport belts  1230  and  1240 . In some embodiments, the transport belts  1230  and  1240  may be ramped to move the FOUP  170  from a height of the turntable  1220  to a height of the equipment load port  1250 .  
         [0070]      FIG. 13  illustrates a method of using the transport system  1200  illustrated in  FIGS. 12A and 12B  to transfer a FOUP  170  to and from a machine load port, according to various embodiments of the invention. The method may be implemented using a combination of computer systems comprising both hardware and software coupled with the transport system  1200  over a communications transmission path.  
         [0071]     In step  1301 , a command to process wafers within the FOUP  170  is received. The command may be first determined and transmitted by a computer system and/or operator configured to control the movement of FOUPs  170  throughout a transport system comprising a plurality of transport systems  1200 , conveyance sections  200 , and other related transport devices.  
         [0072]     In step  1302 , the transport belts  110  and  120  move the FOUP  170  onto the turntable belts  1260  and  1270  disposed on the turntable  1220 .  
         [0073]     In step  1303 , the turntable  1220  rotates the FOUP  170  to align the turntable belts  1260  and  1270  with the transport belts  1230  and  1240 . In some embodiments, the turntable belts  1260  and  1270  may be significantly slowed or stopped while the turntable  1220  rotates.  
         [0074]     In step  1304 , the turntable belts  1260  and  1270  move the FOUP  170  onto the transport belts  1230  and  1240 . The transport belts  1230  and  1240  then move the FOUP  170  to the equipment load port  1250 .  
         [0075]     In step  1305 , a mechanism coupled with the equipment load port  1250  optionally locks the FOUP  170  in place relative to equipment load port  1250 . The mechanism may employ a three point kinematic interface to couple with the FOUP  170 .  
         [0076]     In step  1306 , the mechanism coupled with the equipment load port  1250  opens or removes the FOUP door  310 .  
         [0077]     In step  1307 , the equipment load port  1250  removes material such as semiconductor wafers from within the FOUP  170  for processing, measuring, or sorting by equipment attached to the equipment load port  1250 .  
         [0078]     In step  1308 , the equipment load port  1250  replaces material such as semiconductor wafers to the FOUP  170  after processing, measuring, or sorting by equipment attached to the equipment load port  1250 .  
         [0079]     In step  1309 , the mechanism coupled with the equipment load port  1250  replaces or closes the FOUP door  310 .  
         [0080]     In step  1310 , the mechanism coupled with the equipment load port  1250  optionally unlocks the FOUP  170  in place relative to equipment load port  1250 . The transport belts  1230  and  1240  then move the FOUP  170  from the equipment load port  1250  onto the turntable belts  1260  and  1270 . The turntable  1220  then rotates the FOUP  170  to approximately align the turntable belts  1260  and  1270  with the transport belts  110  and  120 .  
         [0081]     In step  1311 , the transport belts  110  and  120  transport the FOUP  170  along a conveyance direction to another location.  
         [0082]      FIG. 14  illustrates a vertical conveyance section or elevator  1400 , according to various embodiments of the invention. The elevator  1400  may be configured to move the FOUP  170  along a vertical axis  190  from one horizontal plane to another horizontal plane to change the elevation of the FOUP  170 . The elevator  1400  may be useful, for example, to move the FOUP  170  from one location at a first horizontal plane, such as a first conveyance section  100 , to another location at a second horizontal plane, such as second conveyance section  100 . In some embodiments, as illustrated in  FIG. 14 , the elevator  1400  raises or lowers the FOUP  170  along a vertical axis  190  as transport belts  110  and  120  transport the FOUP  170  along a horizontal conveyance direction  180 . A horizontally aligned segment of the transport belts  110  and  120  may be placed on the elevator  1400  such that the FOUP  170  may be disposed on the transport belts  110  and  120  while the horizontally aligned segment is moved up or down along a vertical axis  190  to a desired elevation. The horizontally aligned segment of the transport belts  110  and  120  may then move the FOUP  170  off of the horizontally aligned segment to another location.  
         [0083]     As illustrated in  FIG. 14 , elevator belts  1410  and  1420  may be placed in alignment with and perpendicular to the transport belts  110  and  120 . A pair of elevator supports  1430  and  1440  are attached to the elevator belts  1410  and  1420  and configured to be positioned below the level of the FOUP  170 . The elevator belts  1410  and  1420  are configured to raise the elevator supports  1430  and  1440  along the vertical axis  190  such that the elevator supports  1430  and  1440  lift the FOUP  170  up from the transport belts  110  and  120  to a new level. At the new level, another transport mechanism such as a conveyance section  100 , lift  210 , gripper  810 , overhead gripper belts  910 , or the like may be configured to move the FOUP  170  to another location.  
         [0084]     In various embodiments, the elevator  1400  is configured to rotate the FOUP  170  about an axis such that the elevator moves the FOUP  170  to a location at a different elevation and along a different horizontal conveyance direction than the conveyance direction  180  from which the elevator  1400  receives the FOUP  170 . The elevator  1400  may be configured to rotate by an angle of approximately 90 degrees, 180 degrees, 270 degrees, or other arbitrary angles between zero degrees and 180 degrees.  
         [0085]      FIG. 15  illustrates a transport system  1500  comprising several conveyance sections  100  and an elevator  1400  as illustrated in  FIG. 14 . The transport belts  110 A and  120 A at one horizontal plane are configured to transport the FOUP  170  to the elevator  1400 . The rollers  1530  may also be configured to guide the FOUP  170  onto the elevator belts  1410  and  1420  in conjunction with the transport belts  110 A and  120 A. After the FOUP  170  is transferred from the transport belts  110 A and  120 A to the elevator belts  1410  and  1420 , the elevator  1400  is configured to lower or raise the FOUP  170  along a vertical axis  190  (perpendicular to the plane of the drawing) to a destination height of the transport belts  110 B and  120 B. After the FOUP  170  reaches the destination height of the transport belts  110 B and  120 B, the roller  1530  or additional transport belts  110  and  120  may be configured to move the FOUP  170  off the elevator belts  1410  and  1420  onto another set of transport belts  110 B and  120 B at the new height.  
         [0086]     The rollers  1530  or transport belts  110  and  120  may be configured to move laterally along the horizontal axis  195  such that they provide greater clearance between them and the FOUP  170  when the elevator  1400  raises or lowers the FOUP  170  along the vertical axis  190 . Alternatively, the rollers  1530  or transport belts  110  and  120  may be rotated out of the way to provide greater clearance for the FOUP  170  as illustrated in  FIG. 7 .  
         [0087]      FIG. 16  illustrates a method of transferring a FOUP in a vertical direction  190  using the elevator  1400  as illustrated in  FIGS. 14 and 15 . The method may be implemented using a combination of computer systems comprising both hardware and software coupled with the elevator  1400 .  
         [0088]     In step  1601 , a command to move the FOUP  170  to another level is received. The command may be first determined and transmitted by a computer system and/or operator configured to control the movement of FOUPs  170  throughout a transport system comprising a plurality of elevators  1400 , conveyance sections  100 , and other related transport devices over a communications transmission path.  
         [0089]     In step  1602 , the elevator supports  1430  are positioned just below a vertical level of the FOUP  170 .  
         [0090]     In step  1603 , the FOUP  170  is moved to the center of the elevator, for example by transport belts  110  and  120  and/or rollers  1530 .  
         [0091]     In step  1604 , the FOUP  170  is moved to another level along the vertical axis  190  using the elevator  1400 .  
         [0092]      FIG. 17  illustrates a transport section  100  comprising a first transport belt  110  and a second transport belt  120 , the transport section  100  being configured to provide air bearings along a conveyance path between the first transport belt  110  and the second transport belt  120 . The one or more air bearings are provided to additionally support an article while the first transport belt  110  and the second transport belt  120  guide the article in a conveyance direction  180 . As illustrated in  FIG. 17 , region  1740  represents a location where such air bearings can be provided, either below or above the article. Exemplary air bearing generators for providing air bearings within region  1740  are described with respect to  FIGS. 18A-18C . In various embodiments, the first transport belt  110  and the second transport belt  120  are vertical belts, horizontal belts, slanted belts that are oriented in a direction between vertical and horizontal, or combinations thereof. In some embodiments, at least some portion of the first transport belt  110  and/or the second transport belt  120  are substituted with rollers such as vertical rollers or horizontal rollers.  
         [0093]     In some embodiments, one or more air bearings are disposed between adjacent conveyance sections  100 . In these embodiments, the air bearings are typically configured to support an article as the article is transported between a first conveyance section  100  and an adjacent conveyance section  100  along a conveyance direction  180 .  
         [0094]     An air bearing may serve as an air-cushion non-contact supporting system, as described in U.S. Patent Application Publication 2006/0054774 entitled “High-Performance Non-Contact Support Platforms” which is incorporated herein by reference. In some embodiments, a plurality of air bearings are provided proximate to one another and approximately in a line parallel to the conveyance direction  180  along the conveyance path. In other embodiments, a plurality of air bearings are provided proximate to one another and approximately in a line perpendicular to the conveyance direction  180  along the conveyance path. In still other embodiments, a plurality of air bearings are provided proximate to one another in two dimensional groupings. In additional embodiments, one or more air bearings are provided in irregular locations and patterns between transport belt  110  and transport belt  120 .  
         [0095]     In some embodiments, the air bearings are configured to additionally support the article in a central region of the article between edges of the article that are supported by the transport belt  110  and the transport  120 . In various embodiments, the article comprises a substrate including glass, polymer, or semiconductor material. The article may also comprise substrates for the manufacture of liquid crystal, organic light emitting diode or other types of display devices, a memory substrate (such as a hard drive platter substrate or an optical storage device substrate), a photovoltaic device substrate, a battery substrate, or the like. By supporting the central region of the article, the air bearings may reduce stress on the article, and prevent damage or breakage due to bending caused by uneven support across the width of the article between the transport belt  110  and the transport belt  120 . In some embodiments, the air bearings may support an article such as a substrate characterized by an area less than 1 square meter, between 1 square meter and 5 square meters, between 5 square meters and 6 square meters, or between 6 square meters and 7 square meters.  
         [0096]     The air bearings may also reduce physical contact between the conveyance section  100  and the article in comparison with alternative support members such as rollers, consequently reducing friction and vibration. Reduced contact and friction may also reduce contamination of the article and the ambient environment, for example by minimizing scrubbing of material contacting the article during transport.  
         [0097]      FIGS. 18A, 18B , and  18 C illustrate air bearing generators configured to generate the air bearings illustrated in  FIG. 17 .  FIG. 18A  illustrates various embodiments of an air bearing generator  1810 . In these embodiments, the air bearing generator  1810  may be configured to generate an air bearing  1890  by generating an upward air stream  1820 . The upward air stream  1820  forms the air bearing  1890  by providing physical support to the article when the article travels above the air bearing  1890  along the conveyance path. The air bearing generator  1810  may be configured to emit one or more air streams  1820  emanating from one or more holes in a tube or support member. A velocity and quantity of air within the one or more air streams  1820  determines a level of support provided by the one or more air streams  1820  to the article, such as a substrate.  
         [0098]     The air bearing generator  1810  may optionally be configured to output a significantly reduced air stream  1820  or no air stream  1820  when the article is not in a path of the air stream  1820 . For example, the air bearing generator  1810  may be configured to only output the air stream  1820  directly upward if the article is above the air bearing  1890 , and to output a reduced air stream  1820  when there is no article above the air bearing  1890 . In some embodiments, turbulent limited orifices, such as those described in U.S. Pat. No. 6,523,572 entitled “Apparatus for Inducing Forces by Fluid Injection” which is incorporated herein by reference, may be used to limit the air stream  1820  when there is no article above the air bearing  1890 .  
         [0099]      FIG. 18B  illustrates an alternative embodiment of an air bearing generator  1830  utilizing ultrasonic levitation. U.S. Pat. No. 5,810,155 entitled “Object Levitating Apparatus Object Transporting Apparatus and Object Levitating Bearing Along with an Object Levitating Process and Object Transporting Process,” which is incorporated herein by reference, discloses various embodiments of an object levitating apparatus using ultrasonic excitation. Ultrasonic levitation may typically be used to levitate an article, which may be characterized by thicknesses of approximately 1 mm to 2 mm, above a support surface  1840 . Ultrasonic levitation uses ultrasonic waves generated between the support surface  1840  and the article to drive airflow into a space between the article and the support surface  1840 , and to inhibit air from flowing out of the space between the article and the support surface  1840 . In this way, the air bearing generator  1830  creates an air pressure differential between the article and the support surface  1840  compared to the ambient air pressure around the article. The air pressure differential creates an upward force  1850  that forms an air bearing  1890  that in turn levitates the article above the support surface  1840 .  
         [0100]      FIG. 18C  illustrates alternative embodiments of an air bearing generator  1860  utilizing a Venturi vacuum support system. A Venturi vacuum support system supports an article such as a substrate from above rather than from underneath. As an air stream  1870  emanates downward through a Venturi nozzle disposed in the air bearing generator  1860 , a vortex or Venturi is created in the center of the Venturi nozzle. The center of the Venturi or vortex is characterized by a lower air pressure than the ambient air pressure, thereby creating a localized vacuum and a suction force  1880  tending to lift the article upward toward the center of the Venturi nozzle. The air stream  1870  which escapes below the Venturi nozzle in the air bearing generator  1870  forms an air bearing  1890 . The air bearing  1890  creates an equilibrium between the upward suction force  1880  and a downward force caused by the air stream  1870  emanating from the Venturi nozzle within the air bearing generator  1860 .  
         [0101]     Several embodiments are specifically illustrated and/or described herein. However, it will be appreciated that modifications and variations are covered by the above teachings and within the scope of the appended claims without departing from the spirit and intended scope thereof. For example, while the transportation of FOUPs in semiconductor manufacturing have been used herein as an illustrative example, systems and methods of the invention may be configured for transporting alternative materials, such as for example, substrates for the manufacture of liquid crystal, organic light emitting diode or other types of display devices, a memory substrate (such as a hard drive platter substrate or an optical storage device substrate), a photovoltaic device substrate, a battery substrate, or the like. Further, the vertical rollers and vertical belts discussed herein need not be perfectly vertical. The spacing of vertical rollers as illustrated herein is for illustrative purposes only. In various embodiments, vertical rollers may be disposed in a wide variety of spacings, from closely packed to widely dispersed including a single roller or rollers located only at each end of a belt. In various embodiments, horizontal rollers may be disposed in place of vertical rollers, and horizontal belts may be disposed in place of vertical belts.  
         [0102]     In various embodiments, various disclosed elements such as transfer devices and conveyance sections may be disposed in conjunction with, coupled with, and/or integrated with various other disclosed elements so as to configure a system comprising multiple disclosed elements to transport an article from one location to another location. For example, an elevator may be integrated with an equipment load port or a turntable. Support elements such as transition wheels and air bearings may be disposed in any appropriate location throughout a conveyance section or transfer system as appropriate to support and/or guide articles being conveyed through the conveyance section or transfer system. Attributes disclosed with respect to one disclosed element, such as a conveyance section or a transport belt, may be applicable to another disclosed element, such as a gripper belt or an elevator.  
         [0103]     In further embodiments of the lift  210 , the lift  210  can be additionally configured to purge the interior of the FOUP  170 . This would allow the FOUP  170  to be purged with a gas such as clean dry air, or nitrogen, while the FOUP  170  is engaged with the lift  210 . To accomplish the purge, the lift  210  can include one or more needle valves that are positioned to interface with the FOUP valves  1900  shown in the bottom view of the FOUP  170  in  FIG. 19 . For example, two such needle valves can be used to inject the gas and two can be used to allow the FOUP  170  to vent.  
         [0104]     In various embodiments, each of the various belts discussed herein may be replaced by two or more belts. Likewise, each of the various belts discussed herein may be replaced by a combination of belt(s) and guide wheel(s), the guide wheels configured to support a FOUP directly without use of a belt between the guide wheel and the FOUP. In various embodiments, any one or more of the belts discussed herein are each supported by more than two guide wheels.  
         [0105]     The embodiments discussed herein are illustrative of the present invention. As these embodiments of the present invention are described with reference to illustrations, various modifications or adaptations of the methods and or specific structures described may become apparent to those skilled in the art. All such modifications, adaptations, or variations that rely upon the teachings of the present invention, and through which these teachings have advanced the art, are considered to be within the spirit and scope of the present invention. Hence, these descriptions and drawings should not be considered in a limiting sense, as it is understood that the present invention is in no way limited to only the embodiments illustrated.