Patent Publication Number: US-2007098526-A1

Title: Substrate transportation system

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application is a divisional application of application Ser. No. 11/236,803, filed Sep. 28, 2005. 
    
    
     TECHNICAL FIELD  
      The present invention relates to a substrate transportation system for transporting a substrate to a processing device.  
     BACKGROUND ART  
      Conventionally, a substrate transportation system which transports a substrate to a processing device is known. Particularly, a system is known well which stores a plurality of substrates in a substrate storing cassette called an FOUP and transports the substrates in the cassette as a batch (for example, see Japanese Patent Laid-Open No. 06-016206).  
      In the conventional system which transports the plurality of cassettes in the cassette at once as a batch, when the substrate size is large, the risk concerning accidents during transportation increases. Also, the system scale increases, and accordingly the system is not appropriate for many-product-type, small-lot production.  
     DISCLOSURE OF INVENTION  
      The present invention has been made to solve the problems of the above prior art, and has as its object to provide a versatile substrate transportation system which can cope with various types of processing devices with higher degrees of freedom.  
      In order to achieve the above object, according to the present invention, there is provided a substrate transportation system including a tunnel which transports a substrate one by one and an interface device which delivers the substrate between the tunnel and a processing device, characterized in that the interface device can cope with a plurality of types of processing devices.  
      In order to achieve the above object, according to the present invention, there is provided another substrate transportation system including a tunnel which transports a substrate one by one and an interface device which delivers the substrate between the tunnel and a processing device, characterized in that the interface device is arranged under the tunnel and has means for delivering the substrate vertically to and from the tunnel.  
      The interface device is characterized by including substrate moving means capable of moving the substrate vertically to substrate loading ports of the plurality of types of processing devices. The interface device is characterized by detachably including a hand to load the substrate to substrate loading ports of the plurality of types of processing devices. The interface device is characterized by having a substrate loading port from the tunnel and a substrate unloading port to the processing device, including openable/closeable doors at the substrate loading port and substrate unloading port, and having a chamber function. The interface device is characterized by including first transporting means for delivering the substrate from the tunnel to the processing device, and second transporting means for delivering the substrate from the processing device to the tunnel. The substrate transportation system is characterized by comprising buffer means for buffering vibration between the tunnel and interface device. The tunnel is characterized by having a window portion. The interface device is characterized by including direction adjusting means for adjusting a direction of the substrate to be delivered to the processing device. The interface device is characterized by including information reading means for reading information added to the substrate. The interface device is characterized by including transporting means capable of transporting the substrate in two directions to load the substrate to substrate loading ports of the processing devices on the two sides when the processing devices are provided on two sides of the interface device. The substrate transportation system is characterized by including a plurality of interface devices each of which delivers the substrate to and from a corresponding processing device, and in that the plurality of interface devices include delivery means for delivering the substrate to and from the processing device arranged on one side of the tunnel.  
      Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
       FIG. 1A  is a perspective view showing the appearance of a substrate transportation system according to the first embodiment of the present invention;  
       FIG. 1B  is a view showing the arrangement of interface devices according to the first embodiment of the present invention;  
       FIGS. 2A and 2B  are views showing the internal structures of a tunnel and interface device according to the first embodiment of the present invention;  
       FIGS. 3A and 3B  are views each showing a connecting portion between the tunnel and interface device according to the first embodiment of the present invention;  
       FIG. 3C  is a perspective view showing the internal structure of the tunnel according to the first embodiment of the present invention;  
       FIGS. 4A and 4B  are views showing the structure of a substrate transport car according to the first embodiment of the present invention;  
       FIG. 5  includes views for explaining the substrate delivery operation of a substrate transportation system according to the first embodiment of the present invention;  
       FIG. 6  includes views for explaining the substrate delivery operation of the substrate transportation system according to the first embodiment of the present invention;  
       FIGS. 7A and 7B  are views showing another example of an interface device according to the present invention;  
       FIG. 8A  is a view for explaining the entire layout of the substrate transportation system according to the first embodiment of the present invention;  
       FIG. 8B  is a view for explaining the entire layout of the substrate transportation system according to the first embodiment of the present invention;  
       FIGS. 9A  to  9 E are views showing various layout patterns of the tunnel and processing device according to the first embodiment of the present invention;  
       FIG. 10  is a plan view showing the internal structure of a transfer device which does not have a substrate storing function;  
       FIG. 11A  is a plan view showing the internal structure of a transfer device which has a substrate storing function;  
       FIG. 11B  is a side sectional view showing the internal structure of the transfer device which has the substrate storing function;  
       FIGS. 11C and 11D  are views showing another example of a transfer device which has a substrate storing function;  
       FIG. 12A  is a plan view showing the internal structure of a transfer device which has reading devices;  
       FIG. 12B  is a side sectional view showing the internal structure of the transfer device which has the reading devices;  
       FIG. 13  is a view for explaining the structure and operation of an interface device according to the second embodiment of the present invention;  
       FIG. 14  is a view for explaining the structure and operation of the interface device according to the second embodiment of the present invention;  
       FIG. 15  is a view for explaining the structure and operation of the interface device according to the second embodiment of the present invention;  
       FIG. 16  is a view for explaining the structure and operation of the interface device according to the second embodiment of the present invention;  
       FIG. 17  is a view for explaining the structure and operation of the interface device according to the second embodiment of the present invention;  
       FIG. 18  is a view for explaining the structure and operation of the interface device according to the second embodiment of the present invention;  
       FIG. 19  is a view showing a modification of the interface device according to the second embodiment of the present invention;  
       FIGS. 20A and 20B  are schematic views showing the internal structure of a tunnel according to the third embodiment of the present invention;  
       FIG. 21  is a schematic view showing the internal structure of a tunnel and interface device according to the fourth embodiment of the present invention;  
       FIGS. 22A  to  22 E are views for explaining rail switching operation in a tunnel according to the fifth embodiment of the present invention;  
       FIGS. 23A and 23B  are views for explaining a rail slide mechanism in the tunnel according to the fifth embodiment of the present invention;  
       FIGS. 24A  to  24 D are views each showing the layout in the tunnel according to still other embodiments of the present invention; and  
       FIGS. 25A  to  25 C are views showing the examples of the distal end shapes of arms according to still other embodiments of the present invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      Preferred embodiments of the present invention will now be exemplarily described in detail in accordance with the accompanying drawings. Note that the relative positions and the like of the constituent elements described in the embodiments are merely examples, and the scope of the present invention is not limited to them unless otherwise specified.  
     First Embodiment  
      (Structure)  
       FIG. 1A  is a schematic view showing the layout of part of a substrate transportation system  100  according to the first embodiment of the present invention.  
      Referring to  FIG. 1A , reference numeral  101  denotes a tunnel;  102 , processing devices which process substrates; and  103 , interface devices which deliver the substrates between the tunnel  101  and processing devices  102 .  
      The tunnel  101  is provided so as to connect the plurality of processing devices  102 . The tunnel  101  and processing devices  102  are connected not directly but via the interface devices  103 . More specifically, the tunnel  101  is connected at its lower surface to each interface device  103 , and each interface device  103  is connected at its side surface to the corresponding processing device  102 . The tunnel  101  forms units each having a width almost coinciding with the width of the corresponding interface device  103 . Each unit can be removed for maintenance. The combination of the tunnel  101  and interface device  103  can be handled as one unit. In this embodiment, the interface devices  103  are provided to the plurality of processing devices  102  in one-to-one correspondence.  
      A transport mechanism for transporting the substrate (wafer) is arranged in the tunnel  101 . The substrate transported in the tunnel is transferred to the interface device  103  and then transported from the interface device  103  to the processing device  102 .  
       FIG. 1B  is a view showing the layout of the substrate transportation system  100  from another angle. The upper side of  FIG. 1B  includes a view showing the substrate transportation system  100  from above, and the lower side of  FIG. 1B  includes a schematic sectional view showing the same from the longitudinal direction of the tunnel.  
      For example, when a series of processing devices  102 , e.g., an etcher, asher, wet station, sputter, CMP, stepper, and the like which are necessary for completing a wafer are arranged along the tunnel  101 , as in the view on the upper side of  FIG. 1B , substrate delivery portions  102   a  of the respective processing devices  102  may have different heights. As the height of the tunnel  101  is basically constant, the lengths of communicating portions  104  between the tunnel  101  and interface devices  103  are changed in accordance with the processing devices  102 , and the interface devices  103  are set at heights in accordance with the processing devices  102 . More specifically, for a processing device  102  having a comparatively low substrate delivery portion  102   a , the interface device  103  is set low, as shown in the lower left view of  FIG. 1B . For a processing device  102  having a comparatively high substrate delivery portion  102   a , the interface device  103  is set high, as shown in the lower right view of  FIG. 1B . Thus, the interface devices of one type can cope with a plurality of types of processing devices. While an explanation will be made specifically on transportation of the substrates, the transportation mechanism of this system  100  can transport not only ordinary wafers but also other types of wafers such as a reticle, monitor wafer, dummy wafer, and the like that are mixed. In this case, a controller is preferably provided which synthetically controls transportation of the substrates and reticles in the tunnel. This controller synthetically controls transportation of the substrate transport cars and interface devices so that, e.g., when the type of wafers to be manufactured or the processing conditions for the wafers are changed, a reticle in a reticle storing portion that matches the conditions is placed on the transport car and transported to a predetermined processing device, e.g., a stepper, in which the reticle need be changed, and that the reticle is loaded in the predetermined processing device that requires the reticle.  
       FIG. 2A  is a schematic view showing the interior of the tunnel  101  and that of the interface device  103 .  FIG. 2B  is a view showing the outer appearance of the tunnel  101  and interface device  103  seen from a side A of  FIG. 1A  in the direction of arrow.  
      As shown in  FIG. 2A , two rails  201   a  and  201   b  are provided to the inner side wall of the tunnel  101  to be parallel to each other in the vertical direction. Each of the two rails  201   a  and  201   b  can support a plurality of substrate transport cars  202 . The substrate transport cars  202  are driven by motors to travel along the rail  201   a  or  201   b  in a self-propelled manner. Hence, the tunnel  101  has in it the first transport path which transports the substrates and the second transport path which transports the substrates above the first transport path.  
      Each substrate transport car  202  includes a C-shaped tray  202   a  on which a substrate S can be placed and a cart  202   b  which travels along a rail  201  while supporting the tray  202   a.    
      C of  FIG. 2A  is an enlarged view of a portion near the base of the rail  201 . As shown in C, feeding elements  203  are provided to part of the inner side surface of the tunnel  101 . The feeding elements  203  are arranged at positions where the substrate transport cars  202  stop to load or unload the substrates to and from the processing devices  102 . While stopping, each substrate transport car  202  comes into contact with the corresponding feeding element  203  to receive power to a battery (not shown) in the substrate transport car  202 . The motor is driven by the power accumulated in the battery so that the substrate transport car  202  travels on the rail.  
      Cleaning units  301  each including an air clean filter (ULPA (Ultra Low Penetration Air) filter) are provided in the tunnel  101 . Each cleaning unit  301  is connected to a pipe  302 . Air flowing into the cleaning unit  301  through the pipe  302  is cleaned as it passes through the air cleaning filter of the cleaning unit  301 , flows in the tunnel  101 , as indicated by arrows, and is supplied to an air discharge unit  304  through exhaust ducts  303 . According to this embodiment, the pipe  302  is connected to cover the respective units of the tunnel  101 , as shown in  FIG. 2B . More specifically, the substrate transportation system  100  has a large air supply unit (not shown). The pipe  302  is laid to extend from the air supply unit along the tunnel  101 , and branches midway to be connected to the cleaning units  301  provided to the respective units of the tunnel  101 .  
      Thus, the interior of the tunnel  101  is constantly filled with clean air to prevent dust or the like from attaching to the substrate to be transported. The cleaning units  301  can be removed for maintenance. Although the ULPA filter is provided to each cleaning unit  301  in this embodiment, the present invention is not limited to this. A clean filter such as an HEPA (High Efficiency Particulate Air) filter may be provided to comply with a predetermined cleanliness.  
      The bottom surface of the tunnel  101  has an opening  101   a  through which the substrate is unloaded to and loaded from the interface device  103 . A shutter  204  is provided to open/close the opening  101   a.    
      In the communicating portion  104 , a shield wall  701  is provided for the purpose of ensuring predetermined sealing properties so that when the substrate is to be delivered between the tunnel  101  and interface device  103 , dust or the like will not attach to the substrate. The shield wall  701  can have a buffering function so vibration will not be transmitted between the tunnel  101  and interface device  103 . In this case, for example, the shield wall  701  can be a freely stretchable member such as a bellows member.  
      The arrangement of the shield wall  701  is not limited to one that allows the tunnel  101  and interface device  103  to communicate with each other. For example, as shown in  FIGS. 3A and 3B , projection walls  701   a  and  701   b  that do not come into contact with each other may be respectively provided to the lower portion of the tunnel  101  and the upper portion of the interface device  103  to surround the substrate delivery opening, thus forming a labyrinth structure. At this time, if the internal pressure between the tunnel  101  and interface device  103  is set higher than the outside, dust or the like will not attach to the substrate.  
      The interface device  103  is arranged below the tunnel  101  at a height corresponding to the substrate reception port of the processing device  102 . The interface device  103  includes a chamber  501  which can form a sealed space, a slide unit  401  which transports the substrate within the chamber  501 , and a substrate elevating unit  601  which transfers the substrate from the substrate transport car  202  to the slide unit  401 . In other words, the substrate elevating unit  601  has the function of delivering the substrate to and from the tunnel  101  in the vertical direction.  
      The chamber  501  has an opening  501   a  on the tunnel  101  side and an opening  501   b  on the process side, which can be opened and closed respectively by gate valves  502  and  503  serving as opening/closing doors.  
      The slide unit  401  includes a slide arm  401   a , slide table  401   b , and slider drive  401   c . When the slider drive  401   c  transmits power to the slide table  401   b , the slide arm  401   a  attached to the slide unit  401  moves back and forth with respect to the processing device  102 . Thus, the substrate placed on the slide arm  401   a  is slid to the left in  FIG. 2A  and transported into the processing device  102 .  
       FIG. 3C  is a perspective view showing the interior of the tunnel  101 . As shown in  FIG. 3C , the cleaning unit  301  can be removed for exchange or maintenance. The window  101   a  and a window  101   b  fitted with transparent plates are formed in the ceiling and side surface of the tunnel  101 , so that the interior of the tunnel  101  can be seen. Thus, the state of the substrate in the tunnel or a trouble occurring in the tunnel can be found instantaneously.  
       FIGS. 4A and 4B  are schematic views showing the internal structure of the substrate transport car  202 .  
       FIG. 4A  shows the internal structure of the substrate transport car  202  seen from above.  FIG. 4B  shows the internal structure of the substrate transport car  202  seen from a lower portion in  FIG. 4A . As shown in  FIG. 4A , the tray  202   a  is C-shaped and has a gap G in part of its periphery. Three chucking ports  211  for chucking and holding the substrate are formed in the upper surface of the tray  202   a . All the chucking ports  211  are connected to a pump unit  212  in the cart  202   b .  
      With the substrate being placed on the tray  202   a , when the pump unit  212  is driven to take air in from the chucking ports  211 , the substrate is chucked to the tray  202   a . The tray  202   a  also has a groove  317  to place the substrate. When the substrate is fitted in the groove  317  and drawn by suction through the chucking ports  211 , the substrate is fixed without being shifted or dropping during transportation.  
      The cart  202   b  includes, in addition to the pump unit  212 , a driving unit  213  which causes the cart  202   b  to travel and a control unit  214  which controls the pump unit  212  and driving unit  213 .  
      The driving unit  213  includes in it a motor  213   a , gears  213   b  and  213   c , and a driving roller  213   d . When the rotation force of the motor  213   a  is transmitted to the driving roller  213   d  through the gears  213   b  and  213   c  to rotate the driving roller  213   d  which is in slidable contact with the rail  201 , the cart  202   b  travels on the rail  201 .  
      The cart  202   b  includes, in addition to the driving roller  213   d , guide rollers  215  to clamp the rail  201  in the vertical direction and guide rollers  216  to horizontally clamp the rail  201  together with the driving roller  213   d . With these guide rollers, the cart  202   b  can stably travel on the rail  201 .  
      (Substrate Delivery Operation)  
      The substrate delivery operation will be described with reference to  FIGS. 5 and 6 . Each of a and e of  FIG. 5  shows the position of the substrate transport car  202  in the tunnel  101  seen from above the tunnel through the ceiling portion of the tunnel  101 . Each of b of  FIG. 5  and b and f of  FIG. 6  shows the partial appearance of the interface device  103  seen from the tunnel  101  side. Each of c, d, f, and g of  FIG. 5  and of a, c, d, e, and g of  FIG. 6  shows the interiors of the tunnel  101  and interface device  103  in the same manner as in  FIG. 2A .  
      First, as shown in a of  FIG. 5 , the substrate transport car  202  on which the substrate S is placed travels along the rail  201  and stops above the interface device  103 .  
      Subsequently, as shown in b and c of  FIG. 5 , the shutter  204  in the lower portion of the tunnel  101  and the gate valve  502  in the upper portion of the interface open. A support shaft provided to the upper surface of the interface device  103  is connected to the center shaft of the disk-like gate valve  502  through an arm. When opening operation is performed to pivot the arm about the support shaft as the center, the gate valve  502  moves from the position to close the opening  501   a  to the position to open it.  
      When the gate valve  502  and shutter  204  are opened, as shown in d, the substrate elevating unit  601  operates to move a push-up rod  601   a  upward so as to push up the substrate S on the tray  202   a.    
      When the push-up operation of the substrate S is completed, as shown in e, the substrate transport car  202  moves toward a portion (downward in  FIG. 5 ) where the gap G is not present. In other words, the substrate transport car  202  is moved such that the push-up rod  601   a  extends through the gap G.  
      When the substrate transport car  202  completely retreats from the substrate delivery position, as shown in f, the substrate elevating unit  601  operates to move the push-up rod  601   a  downward with the substrate S being placed on it.  
      As shown in g, the push-up rod  601   a  is stopped temporarily near the top plate of the interface device  103 . The push-up rod  601   a  is rotated to align the orientation fracture of the substrate S. Orientation fracture alignment means to set a fracture portion formed in part of the substrate S in a predetermined direction. Depending on the type of the processing device  102 , sometimes the substrate needs to be loaded such that it is set in a predetermined direction. When the substrate is to be loaded in such a processing device  102 , the substrate elevating unit  601  serves as a direction adjusting means for adjusting the direction of the substrate. More specifically, an optical sensor (not shown) provided to the upper surface of the top plate of the interface device  103  detects the fracture portion of the substrate S.  
      When the orientation fracture alignment is ended, the push-up rod  601   a  is further moved downward, as shown in a of  FIG. 6 , to place the substrate S on the slide arm  401   a . In this state, the shutter  204  in the lower portion of the tunnel  101  and the gate valve  502  on the upper portion of the interface device  103  move to the closing positions, as shown in b and c. Depending on the type of the processing device  102 , it is checked that the gate valve  502  of the interface device  103  is closed completely. After that, the interior of the chamber  501  of the interface device  103  is pressure-reduced. More specifically, if the processing device  102  is of a type that performs the process under a low pressure, the pressure in the chamber  501  is decreased accordingly. If, for example, the processing device  102  is of a type that performs the process in a high vacuum, a low-vacuum pump  801  and high-vacuum pump  802  are further connected to the interface device  103 , as shown in  FIGS. 7A and 7B , to set a high vacuum state in the chamber  501 . When the processing device  102  requires a low vacuum, only the low-vacuum pump  801  needs to be connected to the interface device  103 , as a matter of course.  
      When pressure reduction in the chamber  501  is completed, the gate valve  503  provided to the processing-side side surface of the interface device is opened, as shown in d of  FIG. 6 . The slider drive  401   c  is operated to slide the slide arm  401   a  attached to the slide table  401   b  toward the processing device  102 , as shown in e.  
      In this state, the processing device  102  receives the substrate S placed on the fork-like distal end portion of the slide arm  401   a , and is set in the states of f and g. After that, the slide arm  401   a  is retreated into the chamber  501  to return to the position of d. When the process for the substrate is completed in the processing device  102 , the slide arm  401   a  is slid again and stands by in the states of f and g. On the processing device  102  side, when the substrate S is placed on the slide arm  401   a  and set in the state of e, the state sequentially changes in the order of d of  FIG. 6 →b &amp; c of  FIG. 6 →a of  FIG. 6 →f of  FIG. 5 →d of  FIG. 5 →c of  FIG. 5 .  
      More specifically, the slide arm  401   a  retreats to load the substrate S in the chamber  501  (d of  FIG. 6 ). The gate valve  503  is closed to restore the pressure in the chamber  501  to the atmospheric pressure (c of  FIG. 6 ). After that, a substrate unloading request is sent to the substrate transport car  202 . The substrate transport car  202  is made to stand by before the substrate receiving position above the interface device  103 , and the shutter  204  and gate valve  502  open (a of  FIG. 6 ). Subsequently, the push-up rod  601   a  moves upward to push up the substrate S on the slide arm  401   a , moves further upward, and stops (f of  FIG. 5 ). The substrate transport car  202  which has been standing by at the standby position moves so that the push-up rod  601   a  extends through the gap G, and then stands by at the receiving position (d of  FIG. 5 ). The push-up rod  601   a  moves downward to transfer the substrate S onto the tray  202   a  of the substrate transport car  202 . After the downward movement of the push-up rod  601   a  is completed, the substrate transport car  202  transports the substrate S to the next processing device. Simultaneously, the shutter  204  and gate valve  502  are closed.  
      (Overall Layout)  
      The overall layout of the substrate transportation system  100  will be described with reference to  FIGS. 8A and 8B  and  FIGS. 9A  to  9 E.  
       FIG. 8A  is a view showing the relationship between the main transport path and sub-transport paths. The substrate transportation system  100  includes a main transport path  901  and sub-transport path  902 . The tunnel  101  of the main transport path  901  is connected to the tunnels  101  of the sub-transport path  902  through transfer devices  903 . The transfer device  903  is a device that transfers the substrate transported in the tunnel  101  of the main transport path  901  to the tunnel  101  of the sub-transport path  902 . The tunnels  101  included in the sub-transport path  902  are linear and have dead ends. Thus, the substrate transferred from the main transport path  901  to the sub-transport path  902  is processed by the processing devices  102  while it reciprocates in the tunnels  101  of the sub-transport path  902 . During this operation, the substrate is transported from the tunnel  101  to the processing devices  102  by the interface devices  103 .  
      The substrate which has been processed in the sub-transport path  902  is transferred to the main transport path  901  again and sent to the next step.  
       FIG. 8B  is a view showing a further overall layout example of the substrate transport system. The system shown in  FIG. 8B  has two main transport paths  901 , each of which is connected to sub-transport paths  902  and  905 . A container warehouse  904  is connected to the ends of the main transport paths  901 . The container warehouse  905  stores containers, each containing substrates, sent from the substrate manufacturing factory, and extracts the substrates one by one from the containers and loads them in the main transport paths  901 .  
      Each sub-transport path  902  has a linear layout in the same manner as that described with reference to  FIG. 8A . Each sub-transport path  905  has an endless tunnel  101 . The substrates are transported in the sub-transport path  905  in one direction so that they can be subjected to one process over and over again. Each main transport path  901  is connected to a processing device group  906  to which the substrates are transported directly not through a subtransport path. The substrates which are transported through the main transport paths  901  and subjected to a series of processes are gathered in a container accommodating device  907 , accommodated in predetermined numbers in containers, and transported to another factory or a later step.  
      The shape of the tunnel  101  in the transport path and the arrangement of the processing device  102  will be described.  FIGS. 9A  to  9 E are views showing various layout patterns of the tunnel  101  and processing device  102 .  
      Of  FIGS. 9A  to  9 E,  FIG. 9A  shows a layout in which processing devices  102  are arranged on the two sides of a transport path including one linear tunnel  101 . To implement this layout, interface devices  103  (not shown) which transport the substrates from the tunnel  101  to the processing devices  102  must have the ability of transporting the substrates to the two sides of the tunnel. With this two-side arrangement, the area required for installing the plurality of processing devices becomes small as a whole. The space in the substrate processing factory can be used effectively to reduce the cost of the factory.  
       FIG. 9B  shows a layout in which processing devices  102  are arranged on the two sides of a transport path including a loop-like tunnel  101 . The transport path partly has a transfer device  903 . The transfer device  903  can transport to the transport path again or store in the transfer devices  903  a substrate which has returned after being subjected to a series of processes.  FIG. 9C  shows a layout in which processing devices  102  are arranged on the two sides of a transport path including two linear tunnels  101 . The transport path partly has a transfer device  903  in  FIG. 9C  as well. The transfer device  903  can transport a substrate, which has returned after being subjected to a series of processes in one tunnel  101 , to the other tunnel  101 . The respective processing devices  102  can be maintained easily from an aisle sandwiched by the tunnels  101  as well.  FIG. 9D  shows a layout in which processing devices  102  are arranged on one side of a transport path including one linear tunnel  101 .  FIG. 9E  shows a layout in which processing devices  102  are arranged on the two sides of a transport path including a linear tunnel  101  alternately in a staggered manner across the tunnel  101 .  
      (Structure of Transfer Device)  
      The internal structure of each of the transfer devices  903  shown in  FIG. 8A  will be described with reference to FIGS.  10  to  12 B.  
       FIG. 10  is a plan view showing the internal structure of a transfer device  903  which does not have the function of storing the substrate. The transfer device  903  serves to transfer the substrate S between the main transport path  901  and a sub-transport path  902   a  or  902   b . Referring to  FIG. 10 , a rail  201   a  which continuously extends from the inside of the tunnel  101  of the main transport path  901 , and rails  201   b  and  201   c  which continuously extend from the inside of the tunnels  101  of the sub-transport paths  902   a  and  902   b  are arranged in the transfer device  903 . Thus, a substrate transport car  202  which travels in the tunnel  101  of the main transport path  901  can enter and leave the transfer device  903 .  
      Push-up tables  1001   a ,  1001   b , and  1001   c  corresponding in number to the rails, and a transfer robot  1002  are also arranged in the transfer device  903 . When the substrate transport car  202  which has been transported along the rail  201   a ,  201   b , or  201   c  stops above the push-up table  1001   a a,  1001   b , or  1001   c , the push-up table  1001   a ,  1001   b , or  1001   c  pushes up from below the substrate S transported by the substrate transport car  202 . In this state, when the substrate transport car  202  leaves, the U-shaped hand of the transfer robot  1002  enters the space below the substrate left on the push-up table  1001   a ,  1001   b , or  1001   c . When the push-up table  1001   a ,  1001   b , or  1001   c  lowers, the substrate is placed on the transfer robot  1002 . When the transfer robot  1002  rotates, the substrate S is placed on another push-up table, and transferred to a substrate transport car  202  on a different rail. In order to perform this transfer process smoothly, the arm of the transfer robot  1002  has joint portions at at least two portions, so that it can move the substrate S very freely.  
      A transfer device  903  which has the function of storing the substrate will be described with reference to  FIGS. 11A  to  11 D and  FIGS. 12A and 12B .  FIG. 11A  is a plan view showing the internal structure of the transfer device  903  which has the function of storing the substrate, and  FIG. 11B  is a side sectional view of the same. The transfer device  903  serves to transfer the substrate between the main transport path  901  and a sub-transport path  902   a  or  902   b  and store the substrate. As the substrate S is stored one by one in this manner, the number of substrates which are to be transported by the sub-transport path and main transport path can be adjusted. Thus, the transfer device  903  serves as a buffer in case the processing load increases.  
      The transfer device  903  shown in  FIGS. 11A and 11B  has a stocker  1101  as well as a transfer robot  1102  having two arms  1102   a  and  1102   b . Except for this, the structure of the transfer device  903  is the same as that shown in  FIG. 10 . Accordingly, the same mechanism is denoted by the same reference numeral, and a description thereof will be omitted. With the transfer device provided with the stocker  1101 , the number of substrates S to be transferred increases. Hence, the transfer robot  1102  desirably has the two arms  1102   a  and  1102   b  in this manner, but a transfer robot  1102  of a type shown in  FIG. 10  which has only one arm can also naturally be used. The arms  1102   a  and  1102   b  of the transfer robot  1102  serve in the same manner as the arm of the transfer robot  1002  described with reference to  FIG. 10 , and accordingly a description thereof will be omitted.  
      The stocker  1101  has the shape of an octagonal prism, and rotates as indicated by an arrow so that substrates can be inserted in eight shelves  1101   d  from eight surfaces.  FIG. 11A  shows a state wherein substrates are stored in four out of eight shelves. When a substrate S is to be inserted in the shelf, a door 1101   a  is opened as shown in  FIG. 11A . A cleaning unit  1101   b  is arranged at the center of the upper surfaces of the eight shelves, and blows off clean air downward as indicated by arrows. Another cleaning unit may also be provided on the transfer device  903 .  
      As shown in  FIG. 11B , in each of the eight shelves  1101   d , a plurality of substrate storage rooms  1101   e  pile up vertically. A stocker rotating device  1101   c  is provided under the eight shelves to rotate the entire stocker  1101  clockwise or counterclockwise.  
      To be able to transport the substrates to the respective substrate storage rooms  1101   e  that are continuous vertically, the transfer robot  1102  can move vertically as well. In this case, in place of the push-up tables  1001 , tables that are vertically immobile can be used. Alternatively, the transfer robot  1102  can receive the substrate S from the substrate transport car  202  directly. To be able to receive the substrate S from the substrate transport car  202  directly, the hands formed at the distal ends of the arms  1102   a  and  1102   b  of the transfer robot  1102  must have shapes that conform to the tray shape of the substrate transport car  202 .  
      As shown in  FIG. 11B , the main transport path  901  and sub-transport path  902  are desirably shifted from each other vertically so their rails do not come into contact with each other. Although the stocker  1101  is described as one that stores the substrates, a stocker that stores reticles can be implemented by completely the same structure. The substrates and reticles can be stored in one stocker. The shape of the stocker is not limited to an octagonal prism but can be a cylinder. A flat shelf that does not rotate can be used as a stocker if the transfer robot  1102  has a mechanism that moves vertically and horizontally.  
       FIG. 11C  is a plan view for explaining another example of the stocker  1101 , and  FIG. 11D  is a partial sectional view taken along X-X of  FIG. 11C . In the example shown in  FIGS. 11C and 11D , a plurality of substrate storage rooms  1101   e  are formed on respective annular tables  1101   f , and the tables  1101   f  are supported at their central portions by respective coreless motors. Thus, the substrate storage room  1101   e  of each stage is integrally movable. The entire stocker  1101  has a multilayer structure in which the tables  1101   f  and coreless motors pile up vertically. This will be described in detail. Each coreless motor includes an annular rotary portion  1101   g  and annular stationary portion  1101   h . The rotary portion  1101   g  can rotate relative to the stationary portion  1101   h . The lower surface of the table  1101   f  is fixed to the upper surface of the rotary portion  1101   g , and the lower surface of the stationary portion  1101   h  is fixed to the upper surface of a stationary member  1101   i . The stationary members  1101   i  of the respective stages are connected to each other through a plurality of cylindrical support members  1101   j  to form a coreless tower as a whole. A cleaning unit (not shown) is provided above the coreless portion located at the center of the stocker  1101 , and blows off clean air downward as indicated by arrows.  
      As the motors are provided to the respective stages in this manner, the loads to the respective motors can be decreased, so that the motors can rotate and stop accurately at a high speed. The operation of storing and replacing the reticles, substrates, or the like in the stocker  1101  can be performed efficiently. The reticles and substrates can be separately stored in the separate stages, so that they can be managed easily.  
       FIGS. 12A and 12B  are views for describing a transfer device  903  which has reading devices  1201  for reading information on the substrate. The transfer device  903  shown in  FIGS. 12A and 12B  has the reading devices  1201 , which read information added to the reticle, substrate, or the like, above respective push-up tables  1001   a ,  1001   b , and  1001   c . Except for this, the structure of the transfer device  903  is the same as that of the transfer device  903  shown in  FIGS. 11A and 11B . Thus, the same mechanism is denoted by the same reference numeral, and a description thereof will be omitted.  
      Each reading device  1201  reads information added to the reticle, substrate, or the like and transmits storage information on the reticle, substrate, or the like stored in a stocker  1101  to an information management device (not shown). Hence, the number of substrates or reticles in the stocker  1101  can be managed. On the basis of the information from the information management device, a reticle or substrate corresponding to the request from each processing device  102  is extracted from the stocker  1101  and transported to a target processing device. While the reading devices  1201  are arranged above the push-up tables  1001   a ,  1001   b , and  1001   c , they may be arranged in substrate storage rooms  1101   l e of the stocker  1101 . If information is managed by using a wireless communication IC memory (wireless IC tag), information on a plurality of reticles, substrates, or the like can be communicated at once, so that information on the reticles, substrates, or the like in the stocker  1101  can be managed real time.  
      In the above embodiment, one stocker is contained in the transfer device. Alternatively, a plurality of stockers may be contained in the transfer device.  
     Effect of This Embodiment  
      As described above, according to this embodiment, as the substrates or the like are transported individually in the tunnel, the environment around the substrates or the like can be cleaned at high accuracy, and accordingly the substrate processing accuracy improves. Since the interface devices are made versatile to cope with various processing devices, a large number of interface devices need not be prepared to match the respective processing devices, and the facility cost of the system as a whole can be reduced. When the interface devices are arranged below the tunnel, various processing devices having substrate loading ports at different heights can be coped with by only changing the positions to install the interface devices. Thus, the system can become more versatile. Since substrate delivery between the tunnel as the transport path and the interface device is realized by a push-up mechanism, the substrate can be delivered to and from an interface device set at any height by only changing the push-up stroke. Thus, the system can become more versatile. If an orientation fracture alignment mechanism is built in the push-up mechanism, the apparatus can be made further compact. Since the interface device can include a chamber that can deal with a vacuum, a pressure switching device for switching the pressure need not be additionally provided. The facility installation area can be used effectively, so that the facility cost can be reduced greatly.  
      Since the plurality of substrate transport cars travel in one tunnel in a multiple manner, the respective substrate transport cars can travel in two directions independently of each other, and can overtake each other. Thus, the substrates can be transported without congestion.  
     Second Embodiment  
      An interface device according to the second embodiment of the present invention will be described with reference to FIGS.  13  to  18 . The interface device according to this embodiment is different from that of the first embodiment in that it has a robot arm in its chamber  1302 . Except for this, the structure of the second embodiment is the same as that of the first embodiment. Accordingly, the same structure is denoted by the same reference numeral, and a detailed description thereof will be omitted.  
      FIGS.  13  to  18  are views showing the interior of the chamber  1302  of an interface device  103  according to this embodiment, in which a of each of FIGS.  13  to  18  is a plan view of the interior of the chamber  1302 , and b of the same is a front view of the interior of the chamber  1302 . Also, c of  FIG. 13  is a left side view of the interior of the chamber  1302 . For the sake of descriptive convenience, in FIGS.  13  to  18 , the wall surface portion of the chamber  1302  is shown by a section. Two robot arms  1303  and  1304  are arranged in the chamber  1302 , and are pivotally supported by an arm table  1305  arranged on the bottom portion of the chamber  1302 .  
      The robot arms  1303  and  1304  respectively have hands  1303   a  and  1304   a  which place substrates. The hands  1303   a  and  1304   a  have fork-like distal end portions each similar to a tray  202   a  of a substrate transport car. The gap of the opening of the distal end portion is wider than the diameter of a push-up rod  601   a . Each of the hands  1303   a  and  1304   a  is pivotally connected to one end of the corresponding one of first arm portions  1303   b  and  1304   b . The other end of each of the first arm portions  1303   b  and  1304   b  is pivotally connected to the corresponding one of second arm portions  1303   c  and  1304   c . Furthermore, the other end of each of the second arm portions  1303   c  and  1304   c  is pivotally connected to the arm table  1305 . As shown in c of  FIG. 13 , a cylindrical spacer  1303   d  is provided to the connecting portion of the first arm portions  1303   b  and  1303   c , and accordingly the first arm portions  1303   b  and  1304   b  have different heights. Hence, the hands  1303   a  and  1304   a  do not collide against each other but can move freely in the horizontal direction.  FIG. 13  shows a state wherein both the robot arms  1303  and  1304  stand by at the basic position. At the basic position, the hands  1303   a  and  1304   a  are located at the same position in the horizontal direction. Thus, a of  FIG. 13  shows only the upper hand  1303   a.    
       FIG. 14  shows a state wherein the interface device  103  according to this embodiment receives a substrate S from a tunnel  101 . The process from receiving the substrate from a substrate transport car  202  which travels in the tunnel  101  to placing it on the hand  1303   a  is substantially the same as in the first embodiment. More specifically, the substrate transport car  202  on which the substrate S is placed travels along a rail  201  and stops on the upper portion of the interface device  103 . Subsequently, a shutter  204  in the lower portion of the tunnel  101  and a gate valve  502  on the upper portion of the interface open. A substrate elevating unit  601  operates to move the push-up rod  601   a  upward so as to push up the substrate S on the tray  202   a  of the substrate transport car  202 .  
      When the push-up operation of the substrate S is completed, the substrate transport car  202  is moved so that the push-up rod  601   a  extends through a gap G of the tray  202   a . When the substrate transport car  202  completely retreats from the substrate delivery position, the substrate elevating unit  601  operates to move the push-up rod  601   a  downward with the substrate S being placed on it. Simultaneously, the respective joints of the robot arm  1303  are driven to move the hand  1303   a  so that the push-up rod  601   a  enters the fork-like opening formed at the distal end of the hand  1303   a.    
      The push-up rod  601   a  on which the substrate S is placed stops temporarily before the substrate S reaches the hand  1303   a , rotates the substrate S at the position to align the orientation fracture. When the orientation fracture alignment is ended, the push-up rod  601   a  is further moved downward to place the substrate S on the hand  1303   a , as shown in  FIG. 14 . Then, the shutter  204  in the lower portion of the tunnel  101  and the gate valve  502  on the upper portion of the interface are closed. After that, the internal pressure of the interface device  103  is set to coincide with the pressure of a processing device  102 . Subsequently, a gate valve  503  on the processing device  102  side is opened to project the robot arm  1303  toward the processing device  102 , as shown in  FIG. 15 . When the processing device  102  receives the substrate S placed on the hand  1303   a  of the robot arm  1303 , the robot arm  1303  is retreated to the basic position shown in  FIG. 13 . Then, the gate valve  503  is closed to restore the pressure in a chamber  501  to an atmospheric pressure.  
      The substrate S is then received from the substrate transport car  202  again with completely the same procedure as that described above, to switch to the state of  FIG. 14 . In the state of  FIG. 14 , the lower robot arm  1304  is stretched toward the processing device  102  to switch to the state of  FIG. 16 , so as to receive a processed substrate S 1  from the processing device  102 . In  FIG. 16 , an unprocessed substrate placed on the upper robot arm  1303  is defined as a substrate S 2 .  
      While the lower robot arm  1304  is being retreated, the upper robot arm  1303  is stretched as a replacement toward the processing device  102  to switch to the state of  FIG. 17 . When the processing device  102  receives the unprocessed substrate S 2  placed on the hand  1303   a  of the robot arm  1303 , the robot arm  1303  is retreated to the home position, as shown in  FIG. 18 , and the gate valve  503  is closed to restore the pressure in the chamber  501  to the atmospheric pressure. After that, a substrate unloading request is sent to the substrate transport car  202 . The substrate transport car  202  is made to stand by before the substrate receiving position above the interface device  103 , and the shutter  204  and gate valve  502  are opened. Subsequently, the push-up rod  601   a  moves upward to push up the substrate S 1  on the hand  1304   a , moves further upward, and stops. The substrate transport car  202  which has been standing by at the standby position is moved so that the push-up rod  601   a  extends through the gap G of the substrate transport car  202 . In this state, the push-up rod  601   a  moves downward to place the substrate S 1  onto the tray  202   a  of the substrate transport car  202 . After the downward movement of the push-up rod  601   a  is completed, the substrate transport car  202  transports the substrate S 1  to the next processing device. Simultaneously, the shutter  204  and gate valve  502  are closed.  
      After that, the robot arm  1304  is returned to the basic position shown in  FIG. 13  again. The robot arms  1303  and  1304 , push-up rod  601   a , substrate transport car  202 , shutter  204 , gate valves  502  and  503 , a pump  801 , and the like are operated so that a series of state changes of  FIG. 14 → FIG. 16 → FIG. 17 → FIG. 18 → FIG. 13  is repeated.  
      As described above, when the two-stage robot arms are used, an unprocessed substrate can be loaded into the processing device  102  and a processed substrate can be unloaded from the processing device  102  simultaneously. When compared to a case wherein a processed substrate is set on the substrate transport car and thereafter the next unprocessed substrate is loaded, the substrate process can be performed remarkably quickly.  
       FIG. 19  shows a modification of this embodiment.  FIG. 19  is a view showing the interior of a chamber  1902  of the interface device  103  in the same manner as in  FIG. 13 , in which a is a plan view of the interior of the chamber  1902 , and b is a front view of the interior of the chamber  1902  c is a left side view of the interior of the chamber  1902 . For the sake of descriptive convenience, in  FIG. 19 , the wall surface portion of the chamber  1902  is shown by a section.  
      A slide unit  1903  including two slide arms  1903   a  and  1903   b  is provided in the chamber  1902 . The slide unit  1903  includes a slide table  1903   c  and slider drive  1903   d . Power from the slider drive  1903   d  reciprocally moves the slide arms  1903   a  and  1903   b  attached to the slide table  1903   c  horizontally in the direction of arrows.  
      The slide arms  1903   a  and  1903   b  have fork-like distal end portions in the same manner as the robot arms described above. The gap of the opening of the distal end portion is wider than the diameter of a push-up rod  601   a . The slide arms  1903   a  and  1903   b  are slidably connected to the two side surfaces of the slide table  1903   c , and supported by arms having different shapes so they have different heights, as shown in c of  FIG. 19 . Hence, the slide arms  1903   a  and  1903   b  do not collide against each other but can slide freely in the horizontal direction.  FIG. 19  shows a state wherein both the slide arms  1903   a  and  1903   b  stand by at the basic position. At the basic position, the distal ends of the slide arms  1903   a  and  1903   b  have retreated in a direction opposite to the processing device  102 , in the same manner as in the first embodiment, so that the push-up rod  601   a  on which the substrate is placed can vertically move freely.  
      In the interface device  103  shown in  FIG. 19  as well, when a process similar to that described with reference to FIGS.  13  to  18  is performed, while a processed substrate is being unloaded by one slide arm, an unprocessed substrate can be loaded into the processing device  102  by the other slide arm. Thus, the substrate processing speed can increase in the same manner as that described above.  
      Furthermore, the slide arms  1903   a  and  1903   b  shown in  FIG. 19  can have built-in multi-stage slide mechanisms. In this case, the slide arms not only slide but also become stretchable. Thus, the interface device  103  can be downsized in the widthwise direction of  FIG. 19 .  
     Third Embodiment  
      A tunnel  101  according to the third embodiment of the present invention will be described with reference to  FIGS. 20A and 20B . The tunnel  101  according to this embodiment is different from that of the first embodiment in that it has a reading device to read information added to the substrate. Except for this, the structure and operation of the third embodiment are the same as those of the first embodiment. Accordingly, the same structure is denoted by the same reference numeral, and a description thereof will be omitted.  
       FIGS. 20A and 20B  are schematic views showing only the internal structure of the tunnel  101 , which corresponds to the tunnel portion of  FIG. 2A . In  FIG. 20A , a reading device  2001  is provided to the ceiling portion of the tunnel  101 . In  FIG. 20B , a reading device  2002  is provided to the side wall of the tunnel  101 . The reading device  2001  or  2002  is a reading device to read information recorded on a substrate S to be transported. The reading device  2001  or  2002  may be a barcode reading device if, e.g., a barcode is printed on the substrate S. If a wireless communication IC memory (wireless IC tag) is buried in or added to the substrate S or if an ID tag is added to the substrate S, the reading device  2001  or  2002  may be a receiving device to receive data transmitted from the wireless communication IC memory (wireless IC tag) or ID tag. The reading device  2001  or  2002  can be a character recognition sensor which reads a character recorded on the surface of the substrate S. The wireless communication IC memory (wireless IC tag) is a storage device which includes an antenna to transmit and receive data in an IC microchip. The wireless communication IC memory is operated by the radio waves with a predetermined frequency transmitted from the reading device to transmit and receive the data.  
      While a case has been described wherein the reading device which reads data from an IC tag or ID tag is provided to the tunnel, the reading device may have the function of writing data on an IC tag or the like added to a substrate. In this case, for example, information representing a processing device which has completed the process for the substrate is written on the substrate. Feedback control or feed-forward control is performed on the basis of the processing information to transport the substrate, thus further facilitating substrate transportation control. Furthermore, in place of the reading device, a writing device which writes data on an IC tag or the like added to a substrate may be provided. While a device has been described which reads and writes data on and from the substrate in a noncontact manner, a contact type reading or writing device can naturally be used instead.  
     Fourth Embodiment  
      A tunnel  101  according to the fourth embodiment of the present invention will be described with reference to  FIG. 21 . The tunnel  101  according to this embodiment is different from that of the first embodiment in that it performs self circulation type cleaning. Except for this, the structure and operation of the tunnel  101  are the same as those of the first embodiment. Accordingly, the same structure is denoted by the same reference numerals, and a description thereof will be omitted.  
       FIG. 21  is a schematic view showing the interior of the tunnel  101  and that of an interface device  103 . As shown in  FIG. 21 , in this system  100 , an air discharge unit  304  has a built-in pump function. Air discharged from the air discharge unit  304  is fed to the cleaning units  301  again through a pipe  2101 . Thus, self-circulation type air cleaning can be realized. When compared to a case wherein a pipe is laid to extend along the tunnel  101 , the entire facility can be simplified, and the independence of each unit of the tunnel  101  increases, so that maintenance becomes easy.  
     Fifth Embodiment  
      A tunnel  101  according to the fifth embodiment of the present invention will be described with reference to  FIGS. 22A  to  23 B. A system  100  according to this embodiment has a means for switching the transport path in the tunnel. More specifically, the fifth embodiment is different from the first embodiment in that the system  100  forms one unit to provide a tunnel unit having a rail switching mechanism. Except for this, the structure and operation are the same as those of the first embodiment. Accordingly, the same structure is denoted by the same reference numeral, and a detailed description thereof will be omitted.  
       FIGS. 22A  to  22 E are views for explaining the rail switching operation. First, assume that a substrate transport car  2202   a  traveling along a lower rail  201   b  is to be shifted to an upper rail  201   a . As shown in  FIG. 22A , the substrate transport car  2202   a  is stopped in a tunnel unit  2201  having a rail switching function. Subsequently, as shown in  FIG. 22B , the rails in the tunnel unit  2201  are slid upward. Then, as shown in  FIG. 22C , the substrate transport car  2202   a  is caused to travel. Assume that a substrate transport car  2202   b  traveling along the upper rail  201   a  is to be shifted to the lower rail  201   b . In the state shown in  FIG. 22C , the substrate transport car  2202   b  is stopped in the tunnel unit  2201 . As shown in  FIG. 22D , the rails are slid downward. Then, as shown in  FIG. 22E , the substrate transport car  2202   b  is caused to travel.  
       FIGS. 23A and 23B  are views for explaining a rail slide mechanism in the tunnel unit  2201 .  FIG. 23A  is a schematic view of the tunnel seen from the longitudinal direction, and  FIG. 23B  is a schematic view of the tunnel seen from the left side in  FIG. 23A . Referring to  FIGS. 23A and 23B , both the rails  201   a  and  201   b  are fixed to a rail support member  2301 . The rail support member  2301  extends in a groove  2302   a  of a guide member  2302  and is fixed to a belt  2303 . The belt  2303  can be vertically reciprocated by a motor  2304 . On the two sides of the support member  2301 , the rails  201   a  and  201   b  are fixed to auxiliary support members  2305   a  and  2305   b . The auxiliary support members  2305   a  and  2305   b  are slidable along grooves in auxiliary guide members  2306   a  and  2306   b.    
      In this structure, when the motor  2304  is driven, the rail support member  2301  vertically moves together with the belt  2303 . The rails  201   a  and  201   b  vertically slide while maintaining the gap between them.  
      In this embodiment, the rail pair is slid by using the motor  2304  and belt  2303 , but the present invention is not limited to this. For example, the rail pair may be slid by another mechanism such as a wire takeup mechanism or pressure cylinder.  
     Other Embodiment  
      In the above embodiment, two rails are provided in the tunnel, but the number of rails in the tunnel is not limited to this, but can be three or more, or one.  
      The layout in the tunnel is not limited to that shown in the first embodiment. For example, as shown in  FIG. 24A , a substrate transport car  2401  which travels along an upper rail  201   a  and a substrate transport car  402  which travels along a lower rail  201   b  may have different structures. More specifically, a tray  2401   a  of the substrate transport car  2401  which travels along the upper rail  201   a  may have an L-letter shape to decrease the distance to a tray  2402   a  of the lower substrate transport car  2402 . Then, the ceiling of the tunnel can be lowered, and the structure of the tunnel as a whole can be made compact.  
      As shown in  FIG. 24B , rails  201   a  and  201   b  may be laid on the bottom portion of the tunnel. In this case, a substrate transport car  2401  which travels along the rail  201   a  and a substrate transport car  2402  which travels along the rail  201   b  must have different structures so that the respective trays travel to maintain a vertical gap between them. Then, when compared to a case wherein rails are provided to the tunnel side wall, a bending stress does not easily occur to the rails, so that the substrate transport cars can travel comparatively stably.  
      Furthermore, as shown in  FIG. 24C , rails  201   a  and  201   b  may be laid to extend outside the tunnel, and only the trays of the substrate transport cars may be accommodated in the tunnel. Then, dust which is raised as the substrate transport cars travel does not attach to the substrate, and the environment where the substrate travels can be made very clean. Also, as shown in  FIG. 24D , a rail  201   a  may be laid on the tunnel side wall, and a rail  201   b  may be laid on the tunnel bottom portion. While the air cleaning unit is set on the tunnel ceiling portion, it may be set on either tunnel side wall.  
      In the above embodiments, a structure has been described in which the slide unit can move the substrate only horizontally in the chamber, but the present invention is not limited to this. For example, the robot or slide unit may be further provided with an elevating mechanism which can move the substrate vertically. In this case, the substrate can be moved vertically to the substrate loading ports of the plurality of types of processing devices. While the processing device stands by at its delivery position to deliver the substrate, the substrate can be delivered to a table (not shown) of the processing device.  
      In the above embodiments, as an arm which transports the substrate to the processing device in the interface device, one having a U-shaped fork-like hand at its distal end is shown, but the present invention is not limited to this. For example, various types of hands as shown in  FIGS. 25A  to  25 C can be employed. More specifically,  FIG. 25A  shows a C-shaped hand having a circular distal end,  FIG. 25B  shows an O-shaped hand having a hole in which a push-up rod is to be inserted, and  FIG. 25C  shows a U-shaped hand which opens sideways to the processing device. These hand portions can be made detachable so that they can be exchanged in accordance with the types of the processing devices.  
      When processing devices are arranged on the two sides of the tunnel, openings may be formed in the two side surfaces of each interface device, and one transporting means can be moved toward and away from the processing devices on the two sides. In particular, if the substrates are to be transported to the processing devices on the two sides by using robots, the space where the facilities are installed can be utilized more effectively.  
      In the structure of the above embodiment, power is supplied from the feeding elements  203  to the substrate transport cars  202 , and the substrate transport cars  202  are transported on the rails by the motors in the substrate transport cars  202 . However, the present invention is not limited to this structure. A structure in which the substrate transport cars are levitated and transported by air or magnetism is also incorporated in the present invention.  
      According to the present invention, a versatile substrate transportation system can be provided which can cope with various processing devices with high degrees of freedom.  
      The present invention is not limited to the above embodiments and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, to apprise the public of the scope of the present invention, the following claims are made.