Patent Publication Number: US-2023154777-A1

Title: Substrate transfer apparatus and substrate transfer method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2021-185146 filed on Nov. 12, 2021, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a substrate transfer apparatus and a substrate transfer method. 
     BACKGROUND 
     In a semiconductor device manufacturing process, a semiconductor wafer (hereinafter, referred to as “wafer”) that is a substrate is transferred and processed in an apparatus. 
     Japanese Laid-open Patent Publication No. 2020-170866 discloses an apparatus in which a plurality of vacuum modules, each being provided with a robot for transferring a wafer, are arranged and connected to each other by vacuum lines. Each vacuum module is connected to a processing module and configured to transfer a wafer using a robot. A multi joint arm having a bottom portion disposed on the floor of the vacuum module is described as an example of the robot. The shape of the vacuum line is not described. 
     SUMMARY 
     The present disclosure provides a substrate transfer apparatus capable of suppressing an increase of an occupied floor area and a weight. 
     In accordance with an aspect of the present disclosure, there is a substrate transfer apparatus comprising: a circular tube having a tube axis extending in a lateral direction and having a transfer region for a substrate in the circular tube; a magnetic field generating portion having a magnetic field generating surface facing the transfer region and configured to generate a magnetic field on the magnetic field generating surface; and a transfer body configured to transfer the substrate while moving in a plane direction of the magnetic field generating surface in a state that the transfer body is distant from the magnetic field generating surface by the magnetic field. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the present disclosure will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a plan view of a substrate processing apparatus including a substrate transfer module according to an embodiment of the present disclosure; 
         FIG.  2    is a vertical cross-sectional view of a vacuum transfer module along the tube axis of the module; 
         FIG.  3    is a longitudinal cross-sectional view of the vacuum transfer module perpendicular to the tube axis; 
         FIG.  4    is a perspective view of a circular tube that constitutes the vacuum transfer module; 
         FIG.  5    is a front view of a flange at the end of the circular tube that constitutes the vacuum transfer module; 
         FIG.  6    is a perspective view of a transfer body and a floor plate provided in the substrate processing apparatus; 
         FIG.  7    explains an example of nitrogen gas supply in the vacuum transfer module; 
         FIG.  8    explains separation of the circular tube; 
         FIG.  9    explains extraction of a magnetic field generating portion from the circular tube; 
         FIG.  10    is a longitudinal cross-sectional view of the vacuum transfer module in the case of providing a temperature control mechanism; 
         FIG.  11    is a longitudinal cross-sectional view of a vacuum transfer module to which a cleaning liquid supply mechanism is applied; 
         FIG.  12    is a longitudinal cross-sectional view of the vacuum transfer module having a double tube structure; 
         FIG.  13    is a plan view showing a configuration example in which the substrate processing apparatuses are connected to each other; 
         FIG.  14    is a longitudinal cross-sectional view of a vacuum transfer module having different magnetic field generating surfaces; and 
         FIG.  15    is a perspective view of a vacuum transfer module having a magnetic field generating surface forming a circular tube. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a substrate processing apparatus  1  including a substrate transfer apparatus according to an embodiment of the present disclosure. The substrate processing apparatus  1  is installed in an atmospheric environment and includes a loader module  2 , a load-lock module  25 , a vacuum transfer module  3 , and eight processing modules  7 . Each processing module  7  processes a wafer W that is a circular substrate in a vacuum atmosphere. 
     The loader module  2  is referred to as “equipment front end module (EFEM)” and loads and unloads the wafer W to and from a transfer container C referred to as “front open unified pod (FOUP)” accommodating wafers W. A wafer W unloaded from the transfer container C is loaded into the substrate processing apparatus  1 . The loader module  2  is horizontally elongated, and has an inner atmosphere maintained in an atmospheric atmosphere and a normal pressure atmosphere. Hereinafter, the lengthwise direction of the loader module  2  will be described as the X direction, and the direction perpendicular to the X direction will be described as the Y direction. The X and Y directions are horizontal directions. One side and the other side in the X direction will be described as the +X side and the −X side, respectively, and one side and the other side in the Y direction will be described as the +Y side and the −Y side, respectively. 
     On the −Y side of the loader module  2 , three container placing tables  21  for placing the transfer containers C thereon are arranged side by side in the X direction, for example. A transfer mechanism  22  is disposed in the loader module  2 . The transfer mechanism  22  does not magnetically levitate unlike a transfer body  61  to be described later, and is configured as a multi-joint arm that can be raised and lowered and movable in the X direction. The wafer W is transferred between the transfer container C on the container placing table  21  and the load-lock module  25  by the transfer mechanism  22 . 
     The load-lock module  25  is disposed on the +Y side of the loader module  2 , and the vacuum transfer module  3  is disposed on the +Y side of the load-lock module  25 . The load-lock module  25  has therein a stage  26  for placing a wafer W. The stage  26  is provided with three lift pins  27  that protrude from and retract below the upper surface of the stage  26 , and the wafer W can be delivered between the transfer body  61  of the vacuum transfer module  3  and the transfer mechanism  22  of the loader module  2  via the lift pins  27 . 
     A door valve  28  is interposed between the load-lock module  25  and the loader module  2 , and a gate valve  29  is interposed between the load-lock module  25  and the vacuum transfer module  3 . N 2  (nitrogen) gas can be supplied into and discharged from the load-lock module  25 , and an inner atmosphere of the load-lock module  25  can be switched between a vacuum atmosphere and a normal pressure atmosphere that is an N 2  gas atmosphere in a state where the door valve  28  and the gate valve  29  are closed. The inner atmosphere of the load-lock module  25  is set to a vacuum atmosphere in the case of transferring the wafer W to the vacuum transfer module  3 , and is set to a normal pressure atmosphere in the case of transferring the wafer W to the loader module  2 . 
     Next, the outline of the vacuum transfer module  3  that is a substrate transfer apparatus will be described with reference to the longitudinal cross-sectional views of  FIGS.  2  and  3   . The vacuum transfer module  3  includes a housing  31 , a magnetic field generating unit  6 , and the transfer body  61 . The magnetic field generating unit  6  and the transfer body  61  are disposed in the housing  31 . The housing  31  has a sealed inner space, and is evacuated to a vacuum atmosphere. The transfer body  61  moves laterally while floating from a floor plate  65  due to the magnetic field generated by the floor plate  65  constituting the magnetic field generating unit  6 , and transfers the wafer W between the load-lock module  25  and the processing module  7  and between the processing modules  7 . Since the transfer body  61  moves in a floating state, dust generation is prevented and the inner spaces of the vacuum transfer module  3  and the processing module  7  are maintained in a clean state. In addition, the occurrence of abnormal processing due to adhesion of foreign substances to the wafer W is suppressed. 
     The housing  31  will be described in detail. The housing  31  includes a joint circular tube  32 , a partition wall  39 , and eight side tubes  34 . The joint circular tube  32  is a straight tube, and a tube axis P of the joint circular tube  32  extends along the Y direction. Therefore, the tube axis P extends laterally, more specifically horizontally.  FIG.  2    is a longitudinal cross-sectional view taken along the tube axis P, and  FIG.  3    is a longitudinal cross-sectional view taken along a direction perpendicular to the axial direction of the tube axis P. In order to avoid complicated illustration, the tube axis P is not illustrated in  FIG.  3    and is illustrated only in  FIG.  2   . 
     The joint circular tube  32  is formed by connecting two circular tubes  33  made of a metal such that the tube axes thereof overlap each other. Therefore, the tube axis P of the joint circular tube  32  coincides with the tube axes of the circular tubes  33 . Among the eight side tubes  34 , four side tubes  34  are attached to one of the circular tubes  33 , and the other four side tubes  34  are attached to the other circular tube  33 . Reference numeral  11  in  FIG.  2    denotes a plurality of support columns arranged at intervals in the Y direction. The support columns  11  supports the two circular tubes  33  on the floor  12  on which the substrate processing apparatus  1  is installed. The heights of the supported circular tubes  33  may be aligned with the height of the load-lock module  25  supported on the floor  12  by a support  13 . 
     The circular tubes  33  are connected to form the joint circular tube  32 , thereby forming a part of the housing  31 . The circular tube  33  will be described with reference to the perspective view of  FIG.  4   . The −Y side end and the +Y side end of the circular tube  33  are widened outward to form flanges  35  and  36 , respectively. Further, two circular openings  37  are disposed on each of the sidewall on the +X side and the sidewall on the −X side while being spaced apart from each other in the Y direction. The two openings  37  on the −Y side face each other, and the two openings  37  on the +Y side face each other. Therefore, the four openings  37  are arranged in a 2×2 matrix shape in plan view. 
     The two side tubes  34  are disposed on each of the −X side and +X side of the outer circumference of the circular tube  33 . Each side tube  34  is an extremely short circular tube, and one ends of the four side tubes  34  are connected to the peripheral portions of the openings  37 . The other ends of the side tubes  34  extend in the direction opposite to the tube axis P along the X direction. The other ends of the side tubes  34  are widened outward from the side tubes  34  to form flanges  38 . 
     Hereinafter, in order to distinguish the two circular tubes  33 , the circular tube positioned on the −Y side may be referred to as “circular tube  33 A” and the circular tube positioned on the +Y side may be referred to as “circular tube  33 B.” Next, the connection between the circular tubes  33 A and  33 B and other members will be described. The flange  35  of the circular tube  33 A is connected to the gate valve  29 . When the gate valve  29  is opened, the circular tube  33 A and the load-lock module  25  communicate with each other so that the wafer W can be transferred between the vacuum transfer module  3  and the load-lock module  25 . The flange  36  of the circular tube  33 B is connected to the partition wall  39 . The partition wall  39  is provided to close the opening on the +Y side of the circular tube  33 B. 
     The processing modules  7  are connected to the flanges  38  of the side tubes  34  in the X direction through gate valves  71 . Hence, transfer paths for wafers W, which are formed by the side tubes  34 , are opened on the side surface of the joint circular tube  32  to be spaced apart from each other along the tube axis P. These transfer paths are opened and closed by the gate valves  71 . The eight processing modules  7  are arranged in a 2×4 matrix shape in plan view. The gate valves  71  connected to the processing modules  7  are closed except when it is required to transfer wafers W, and isolates the atmospheres between the modules. This is also applied to the door valve  28  and the gate valve  29 . The processing modules  7  may be referred to as “processing modules  7 A to  7 D” when it is required to distinguish them. The processing modules  7 A to  7 D are arranged in that order from the −Y side toward the +Y side. In other words, two processing modules  7 A, two processing modules  7 B, two processing modules  7 C, and two processing modules  7 D are provided. 
     Hereinafter, the configuration of the processing modules  7  will be described. Each processing module  7  has a processing container that is evacuated to a vacuum atmosphere by an exhaust mechanism (not shown). The stage  26  provided with the lift pins  27  is disposed in the processing container, similarly to the load-lock module  25 . In addition, the stage  26  in the processing module  7  is provided with a temperature controller, e.g., a heater or a flow path through which a fluid whose temperature is adjusted by a chiller unit flows, so that processing can be performed in a state where a temperature of the wafer W placed on the stage  26  to a desired temperature. 
     The processing container is provided with a gas supply device (not shown) such as a gas shower head or the like, and a processing gas is supplied into the processing container maintained in a vacuum atmosphere. When the wafer W placed on the stage  26  and having a controlled temperature is exposed to the processing gas, the processing using the processing gas is performed. The processing includes etching, film formation, annealing, or the like. In addition, a plasma producing mechanism may be provided so that the processing using plasma produced from the processing gas can be performed. 
     Next, the connection between the circular tube  33 A and the circular tube  33 B will be described with reference to  FIG.  5    that is the front view of the flange  36  of the circular tube  33 A viewed from the +Y side. The flange  36  of the circular tube  33 A and the flange  35  of the circular tube  33 B face each other, and O-rings  41  and  42  are interposed between the flanges  35  and  36  to be in close contact with the flanges  35  and  36 . The O-rings  41  and  42  are annular sealing members that are concentric with respect to a point on the tube axis P, and the diameter of the O-ring  41  is greater than that of the O-ring  42 . Thus, the O-rings  41  and  42  are disposed along the tube openings of the circular tubes  33 A and  33 B. An annular gap  43  is formed between the outer circumference of the O-ring  42  and the inner circumference of the O-ring  41 . 
     The flanges  35  and  36  connected to each other via the O-rings  41  and  42  are fixed to each other by fixing tools (not shown) such as bolts or the like, and the fixing therebetween can be released by removing the fixing tools. In other words, the circular tubes  33 A and  33 B are detachable. Since the circular tubes  33  are detachable, it is possible to facilitate the attachment/detachment of the magnetic field generating unit  6  to/from the housing  31 , which will be described later. Further, since the circular tubes  33 A and  33 B are detachable, N 2  gas flow can be formed in the gap  43  to prevent the atmosphere outside the housing  31  from flowing into the circular tubes  33 A and  33 B through the gap between the flanges  35  and  36 . 
     A mechanism for forming such flow will be described. A downstream end of a line  44  is connected from the −Y side to the flange  36  of the circular tube  33 A. The upstream side of the line  44  is connected to the gap  43  via a hole  44 A bored in a thickness direction (Y direction) of the flange  36 . An upstream end of the line  44  is connected to a gas supply source  40  via a flow rate controller  45 . The gas supply source  40  supplies a clean inert gas such as N 2  gas to the line  44 . The flow rate controller  45  includes a valve or a mass flow controller to control the amount of N 2  gas supplied to the downstream side of the line  44 . 
     An upstream end of an exhaust line  46  is connected from the −Y side to the flange  36 , and a downstream side of the exhaust line  46  is opened to the gap  43  via a hole  46 A bored in the thickness direction (Y direction) of the flange  36 . The position of the hole  44 A and the position of the hole  46 A are spaced apart from each other by about 180 degrees when viewed from the tube axis P so that the N 2  gas can be uniformly supplied to each part of the gap  43 . 
     The downstream end of the exhaust line  46  is connected to an exhaust mechanism  48  via an exhaust amount controller  47 . The exhaust mechanism  48  is, e.g., a vacuum pump. The exhaust amount controller  47  is, e.g., a valve, and controls the exhaust amount from the exhaust line  46 . When the housing  3  is exhausted to a vacuum atmosphere in order to transfer the wafer W, the supply of N 2  gas (second gas) to the gap  43  and the exhaust of the gas from the gap  43  are performed, thereby generating air flow along the circumference of the annular gap  43  as indicated by dashed arrows in  FIG.  5   . Such air flow is constantly formed during the operation of the substrate processing apparatus  1  in which the housing  31  is maintained in a vacuum atmosphere. Even if the atmosphere flows into the gap  43  from the outside of the housing  31 , the atmosphere is carried away by the air flow and exhausted, thereby preventing the atmosphere from flowing into the housing  31 . 
     The circular tube  33 A is a first circular tube, and the circular tube  33 B is a second circular tube. The flange  36  of the circular tube  33 A is a first flange, and the flange  35  of the circular tube  33 B is a second flange. The O-ring  41  is a first sealing member, and the O-ring  42  is a second sealing member. An air flow forming mechanism includes the gas supply source  40 , the flow rate controller  45 , the exhaust amount controller  47 , the line  44 , and the exhaust line  46 . 
     In the following description, it is assumed that flow rate controllers other than the flow rate controller  45  have the same configuration as that of the flow rate controller  45 , and are configured to control the flow rate of the gas flowing toward the downstream side of the line in which the flow rate controller is disposed. The flow rate control includes the setting of the flow rate to 0 (i.e., stopping the gas supply). In the following description, it is also assumed that the exhaust amount controllers other than the exhaust amount controller  47  have the same configuration as that of the exhaust amount controller  47 , and are configured to control the flow rate of the gas flowing toward the downstream side of the exhaust line in which the exhaust amount controller is disposed. 
     The connection between the circular tube  33 B and the partition wall  39  is the same as the connection between the circular tubes  33 A and  33 B. Specifically, the partition wall  39  can be attached to and detached from the flange  36  of the circular tube  33 B via fixing tools, and the O-rings  41  and  42  are interposed between the flange  36  and the partition wall  39 . N 2  gas is also supplied into the gap  43  between the O-rings  41  and  42  and exhausted from the gap  43  through the line  44  and the exhaust line  46 , thereby forming air flow along the circumference of the gap  43 . 
     Next, the transfer body  61  and the magnetic field generating unit  6  will be described with reference to  FIG.  6   . The transfer body  61  includes a moving body  62  and a support  63 . The moving body  62  has a magnet  64  that is a permanent magnet, for example. The support  63  is disposed on the side of the moving body  62 , and the wafer W is supported on the support  63 . In this example, the support  63  has a bifurcated fork shape to avoid interference with the lift pins  27  at the time of delivering the wafer W to each module. 
     The magnetic field generating unit  6  disposed in the housing  31  is provided in each of the circular tubes  33 A and  33 B. The magnetic field generating unit  6  includes a floor plate  65 , columns  68 , and wheels  69 . The floor plate  65  is a flat plate, and a plurality of coils  66  are distributed and embedded therein in the plane direction thereof. A power is individually supplied to each coil  66  from a power supply device  60 . The coil  66  generates a magnetic field on a magnetic field generating surface  67  that is the main surface of the floor plate  65  and directed upward with an intensity corresponding to the power supplied thereto. In other words, each coil  66  acts as an electromagnet. In this example, the magnetic field generating surface  67  forms a horizontal surface. The magnet  64  of the transfer body  61  and the energized coil  66  repel each other due to a magnetic force, and the transfer body  61  floats from the magnetic field generating surface  67 . 
     Since the distribution and intensity of the magnetic field on the magnetic field generating surface  67  are controlled by switching the coils  66  to which the power is supplied and adjusting the amount of power to be supplied, it is possible to move the transfer body  61  in a floating state in the X and Y directions, change the direction, stop the movement, and change a floating height from the magnetic field generating surface  67 . Here, the movement in the X and Y directions include both separate movement in the X and Y directions and simultaneous movement in the X and Y directions. The transfer body  61  can move between different positions over the magnetic field generating surface  67  in the plane direction of the magnetic field generating surface  67 . The support  63  enters a module as a transfer destination in a state where the moving body  62  constituting the transfer body  61  is positioned over the magnetic field generating surface  67 , so that the wafer W is delivered to and from the module. 
     Hereinafter, the floor plate  65  that is a magnetic field generating portion will be described further. The floor plate  65  is elongated in the Y direction, and has a length that is substantially the same as that of the circular tube  33 . The floor plate  65  of the circular tube  33 A and the floor plate  65  of the circular tube  33 B are positioned at the same height, and are in contact with each other. Therefore, the inner space of the joint circular tube  32  is divided into an upper space  51  and a lower space  52  by the floor plate  65  from one end to the other end in the tube axis direction. 
     In the lower space  52 , various devices for driving the substrate processing apparatus  1  are installed, for example. The floor plate  65  is formed by connecting magnetic field generating plates  80  formed in a substantially square tile shape in plan view to each other in the Y direction. In  FIGS.  1  to  6   , the magnetic field generating plates  80  are not illustrated to avoid complicated illustration. The magnetic field generating plate  80  is illustrated in the following embodiment. The side surfaces of the floor plate  65  facing the +X direction and the −X direction are spaced from the inner circumferential surface of the circular tube  33 , and a communication path  50  through which the upper space  51  and the lower space  52  communicate with each other is formed between the side surfaces of the floor plate  65  and the inner circumferential surface of the circular tube  33  (see  FIG.  3   ). 
     The plurality of columns  68  spaced apart from each other at intervals in the Y direction are arranged at each of the +X side end and the −X side end of the floor plate  65  to support the +X side end and the −X side end of the floor plate  65  from below. The wheels  69  are disposed at the lower ends of the respective columns  68 , and can rotate about the axis extending in the X direction. The magnetic field generating unit  6  can be attached to and detached from the circular tube  33  using the wheels  69 . The sequence of the attachment/detachment will be described later. 
     Next, the housing  31  will be further described. In the upper space  51  in the joint circular tube  32 , a heat shield plate  14  that is a heat shield member is disposed above the floor plate  65  to face the floor plate  65 . The heat shield plate  14  extends from one end to the other end in the Y direction of the upper space  51 . The region between the heat shield plate  14  and the floor plate  65  serves as a transfer region  15  where the wafer W is transferred by the transfer body  61 . Therefore, the magnetic field generating surface  67  of the floor plate  65  faces the transfer region  15 , and the heat shield plate  14  is disposed on the opposite side of the magnetic field generating surface  67  with respect to the transfer region  15 . The side tubes  34  are opened to the transfer region  15  so that the transfer body  61  can transfer the wafer W to and from the processing modules  7 . 
     The heat shield plate  14  has a function of shielding the radiant heat directed from the wafer W toward the tube wall of the joint circular tube  32 . In other words, even if the wafer W is processed in the processing module  7  and transferred at a relatively high temperature into the joint circular tube  32 , the heat shield plate  14  prevents the temperature of the tube wall and further the vicinity of the vacuum transfer module  3  from increasing due to the radiant heat from the wafer W. Accordingly, it is possible to prevent the processing performed by another apparatus from becoming abnormal at the outside the substrate processing apparatus  1 , and also possible to prevent an operator from being unable to move or perform an operation. 
     Gas nozzles  53  are disposed at the upper portion of the joint circular tube  32 , and the injection ports of the gas nozzles  53  are directed downward. In other words, the injection ports are opened to the upper space  51 . As shown in  FIG.  2   , the gas nozzles  53  are arranged at intervals in the Y direction. In this example, four gas nozzles  53  are provided. The gas nozzles  53  may be referred to as “gas nozzles  53 A,  53 B,  53 C, and  53 D” arranged from the −Y side toward the +Y side so that they can be distinguished from each other. For example, the Y direction positions of the gas nozzles  53 A,  53 B,  53 C, and  53 D are aligned with the Y direction positions of the processing modules  7 A,  7 B,  7 C, and  7 D, respectively. 
     The gas nozzles  53  are connected to the gas supply source  40  through lines  54 . Each line  54  is provided with a flow rate controller  55 , so that the flow rate of N 2  gas injected from each gas nozzle  53  can be individually adjusted. A plurality of exhaust ports  56  that are opened to the lower space  52  are disposed at the bottom portion of the joint circular tube  32 . The exhaust ports  56  are arranged at intervals in the Y direction. One ends of exhaust lines  57  are respectively connected to the exhaust ports  56 , and the other ends of the exhaust lines  57  are connected to the exhaust mechanism  48  through an exhaust amount controller  58 . The injection ports of the gas nozzles  53  are first gas supply ports. Therefore, the first gas supply ports are opened at different positions in the tube axis direction of the joint circular tube  32 . The N 2  gas injected from the gas nozzles  53  is a first gas. 
     The housing  31  is exhausted from the exhaust ports  56  during the operation of the substrate processing apparatus  1 , so that an inner atmosphere of the housing  31  is set to a vacuum atmosphere of a desired pressure. At the same time, N 2  gas is supplied from the gas nozzles  53 , so that the pressure in the housing  31  reaches a desired vacuum pressure, and the wafer W is transferred. The dashed arrows in  FIG.  3    indicate the flow of the N 2  gas. As shown in  FIG.  3   , the N 2  gas flowing downward in the upper space  51  flows to the position below the heat shield plate  14  and flows downward in the transfer region  15 . Then, the N 2  gas flows into the lower space  52  through the communication path  50 , and then flows into the exhaust ports  56  and is removed. 
     As described above, the N 2  gas injected from the gas nozzles  53  flows as a purge gas to purge the upper space  51  and removes foreign substances such as particles and the like from the upper space  51 . In addition, as described above, even if particles, for example, are generated in the lower space  52  where devices (not shown) are provided, the scattering of the particles into the upper space  51  can be suppressed by the flow of the purge gas. Due to the structure in which the circular tube  33  is divided into the upper space and the lower space and the action of the purge gas supplied to the upper space  51 , the upper space  51  and the wafer W transferred to the transfer region  15  forming the upper space  51  is maintained in a clean state. 
     It is preferable that the pressure in the upper space  51  is higher than that in the lower space  52  so that the flow velocity of the N 2  gas toward the lower space  52  can be increased and the upper space  51  can be cleaned more reliably. In other words, it is preferable to control the amount of N 2  gas supplied from each gas nozzle  53  and the exhaust amount from each exhaust port  56  (i.e., control the operations of the flow rate controller  55  and the exhaust amount controller  58 ) so that the pressure difference can be obtained. The communicating path  50  on the side of the floor plate  65  is formed to have an appropriate width (length in the X direction) so that the pressure difference can be obtained. In order to suppress the gas flow between the processing container of the processing module  7  and the housing  31  at the time of opening the gate valve  71  and the movement of foreign substances such as particles and the like due to the gas flow, it is preferable to minimize the pressure difference between the processing module  7  and the upper space  51 . 
     As described above, the gas nozzles  53 A to  53 D are aligned in the Y direction, and thus are positioned relatively close to two processing modules  7 . Therefore, the N 2  gas injected from the gas nozzles  53 A to  53 D is supplied to the region in the upper space  51  that faces the gate valves  71  connected to the processing modules  7  positioned relatively thereto. The gas nozzles  53  aligned in the Y direction are associated with the gate valves  71  connected to the processing modules  7 , so that each of the flow rate controllers  55  operates such that the flow rate of the N 2  gas from the corresponding gas nozzle  53  changes depending on the opening/closing of the corresponding gate valve  71 . 
     More specifically, the gas nozzles  53  supply N 2  gas at a first flow rate when all the corresponding gate valves  71  are closed. On the other hand, the gas nozzles  53  supply N 2  gas at a second flow rate higher than the first flow rate when one of the two corresponding gate valves  71  is opened. Therefore, the flow rate of the gas from the gas nozzles  53  in the case where any one of the corresponding gate valves  71  is opened is greater than the flow rate of the gas from the gas nozzles  53  in the case where all the corresponding gate valves  71  are closed.  FIG.  7    shows a specific example of the gas flow rate control. In this example of  FIG.  7   , the gate valve  71  connected to the processing module  7 C is opened, and the gate valves  71  connected to the processing modules  7 A,  7 B, and  7 D are closed. Accordingly, N 2  gas is injected from the gas nozzles  53 A,  53 B, and  53 D at the first flow rate, and N 2  gas is injected from the gas nozzle  53 C at the second flow rate. 
     By supplying the N 2  gas at the second flow rate, the flow velocity of the N 2  gas in the region of the upper space  51  that faces the opened gate valve  71  increases, thereby suppressing the diffusion of the gas from the processing module  7  into the housing  31 . As a result, the outflow of foreign substances to the transfer region  15  due to the diffusion of the gas is suppressed. 
     Since the joint circular tube  32  is elongated in the Y direction, the plurality of gas nozzles  53  are provided as described above. If the flow rate of N 2  gas from the gas nozzles  53  is constantly increased in order to enhance the effect of suppressing the diffusion of the gas from the processing module  7 , the amount of N 2  gas used during the operation of the substrate processing apparatus  1  is increased. Since, however, the flow rates of the gases from the gas nozzles  53  are controlled depending on the opening/closing of the corresponding gate valves  71 , it is possible to effectively suppress the diffusion of the gas from the processing module  7  to the upper space  51  while reducing the amount of N 2  gas used. The flow rate controller  55  for controlling the flow rate of the gas supplied to the gas nozzles  53  and the gas supply source  40  constitute a first gas supply device. 
     The flow rate of N 2  gas supplied from the gas nozzles  53  other than the gas nozzle  53  that injects N 2  gas at the second flow rate may be decreased from the first flow rate. In that case, the supply of N 2  gas from the corresponding gas nozzles  53  may be stopped. Specifically, when N 2  gas is injected from the gas nozzle  53 C at the second flow rate as shown in  FIG.  7   , the flow rate of N 2  gas injected from the gas nozzles  53 A,  53 B, and  53 D may be lower than the first flow rate, or the injection thereof may be stopped. 
     The exhaust ports  56  may also be associated with the gate valves  71  positioned relatively close thereto in the Y direction. When all the corresponding gate valves  71  are closed, the exhaust is performed at a first exhaust amount. When any of the corresponding gate valves  71  is opened, the operation of the exhaust amount controller  47  may be controlled such that the exhaust is performed at a second exhaust amount greater than the first exhaust amount. Accordingly, it is possible to increase the flow velocity of the gas in the region facing the corresponding gate valves  71 , and also possible to suppress the diffusion of the gas from the processing module  7  to the upper space  51 . The exhaust amount from the exhaust ports  56  other than the exhaust port  56  having the second exhaust amount may be smaller than the first exhaust amount. In that case, the exhaust from the exhaust ports  56  other than the exhaust port  56  having the second exhaust amount may be stopped. 
     However, the exhaust ports  56  are opened to the lower space  52  partitioned with respect to the upper space  51  in which the gate valves  71  are provided, so that the effect on the air flow in the upper space  51  may be small. Therefore, in order to more reliably obtain the effect of suppressing the diffusion of the gas from the processing module  7 , it is preferable to change the flow rate of the gas from the gas nozzles  53  or to control the exhaust amount from the exhaust ports  56  while changing the gas flow rate. 
     Next, a controller  10  shown in  FIG.  1    will be described. The controller  10  is a computer, and has a program. The program has a group of steps so that control signals can be outputted to individual components of the substrate processing apparatus  1  and the operations of the individual components can be controlled to transfer and process the wafer W as will be described later. Specifically, the operations of the processing modules  7 , such as the operation of the transfer mechanism  22 , the operation of the transfer body  61  by the power supplied from the power supply device  60  to each coil  66 , the opening/closing of the door valve  28  and the gate valves  29  and  71 , the operation of controlling the flow rate of N 2  gas by the flow rate controllers  45  and  55 , the operation of controlling the exhaust amount by the exhaust amount controllers  47  and  58 , and the like are controlled. The program is stored in the controller  10  while being stored in a storage medium such as a hard disk, a CD, a DVD, a memory card, or the like. Hereinafter, the transfer path of the wafer W in the substrate processing apparatus  1  will be described. The wafer W loaded into the loader module  2  from the transfer container C is transferred to the load-lock module  25  and then to the vacuum transfer module  3 . The wafer W is processed in the processing module  7 , and then transferred to the vacuum transfer module  3 , the load-lock module  25 , the loader module  2 , and the transfer container C in that order. Specifically, in the case of transferring the wafer W between the vacuum transfer module  3  and the processing modules  7 , the wafer W may be transferred to only one of the eight processing modules  7  and processed therein, or the wafer W may be sequentially transferred to the eight processing modules  7  and processed therein. 
     It is known that the wafer W passes through a vacuum transfer module in which a multi joint arm is disposed on a floor surface thereof in the case of transferring the wafer W between the load-lock module  25  and the processing modules  7 . In order to secure the space required for revolving the multi-joint arm, the vacuum transfer module has a housing formed in a quadrilateral shape with relatively large widths in the forward-backward direction and in the left-right direction. 
     However, the quadrilateral housing has a large inner space and, thus, the footprint (occupied floor area) becomes relatively large. In addition, when a pressure in the quadrilateral housing is set to a vacuum level, the corner portions of the housing are likely to be deformed because a relatively large force is applied to the corner portions of the housing due to ambient air. If the strength of the corner portions is increased to prevent the occurrence of such deformation, the weight of the housing increases. As a result, relatively high costs or large amount of efforts may be required at the time of transporting or assembling the housing. Further, a large metal base is cut in order to manufacture a quadrilateral housing. Since the amount of cutting is relatively large, it may be difficult to reduce manufacturing costs and improve mass productivity. 
     However, in the case of the vacuum transfer module  3 , the transfer body that is magnetically levitated by the magnetic field generating unit  6  moves in the housing  31  to transfer the wafer W, and the housing  31  is formed by the circular tube  33 . Hence, the increase in the weight of the housing  31  due to the corner portions can be avoided, and there is no need to reinforce the corner portions. In addition, it is not necessary to increase the widths in the forward-backward direction and in the left-right direction in order to secure the space for revolving the multi joint arm. Accordingly, the increase in the footprint of the vacuum transfer module  3  is suppressed. Further, the increase in the weight is suppressed, which makes it possible to easily handle the housing. Furthermore, a conventional mass-produced tube may be used as the circular tube  33  forming the housing  31 , for example. In that case, the costs and efforts for manufacturing the vacuum transfer module  3  can be reduced. 
     Next, an example of an operation performed by an operator in the case of unloading the magnetic field generating unit  6  and the transfer body  61  from the housing  31  for maintenance of the magnetic field generating unit  6  and the transfer body  61  will be described. First, the exhaust from the exhaust ports  56  is stopped and N 2  gas is supplied from the gas nozzles  53 , thereby switching a pressure in the housing  31  from a vacuum pressure to an atmospheric pressure. On the other hand, the magnetic levitation of the transfer body  61  is stopped and the transfer body  61  is landed on the magnetic field generating surface  67 . Then, the circular tubes  33 A and  33 B forming the housing  31  are separated by releasing the connection between the circular tubes  33 A and  33 B (see  FIG.  8   ). 
     Next, by pulling the magnetic field generating unit  6  in the axial direction of the circular tube  33 A through the tube opening of the circular tube  33 A on the flange  36  side, the magnetic field generating unit  6  is unloaded to the outside of the circular tube  33 A together with the transfer body  61  (see  FIG.  9   ). When the transfer body  61  is landed on the magnetic field generating surface  67  in the circular tube  33 A between the circular tubes  33 A and  33 B, the transfer body  61  is also unloaded to the outside of the circular tube  33 A together with the magnetic field generating unit  6 . The unloading of the magnetic field generating unit  6  from the circular tube  33 B is performed in the same manner as the unloading from the circular tube  33 A except that the magnetic field generating unit  6  is unloaded from the tube opening on the flange  35  side. The unloading of the magnetic field generating unit  6  from the circular tubes  33 A and  33 B can be performed with a relatively small force because the wheels  69  roll on the inner circumferential surfaces of the circular tubes  33 A and  33 B. The wheels  69  rotates about the X direction axis as described above, and thus serve as guide members for guiding the relative movement of the magnetic field generating unit  6  along the tube axis P with respect to the circular tubes  33 A and  33 B. 
     In the case of storing the magnetic field generating unit  6  and the transfer body  61  again in the circular tubes  33 A and  33 B after the completion of the maintenance, the operation is performed in the reverse order of the loading operation. In this case as well, the magnetic field generating unit  6  can be moved in the circular tubes  33 A and  33 B with a relatively small force due to the wheels  69 . The magnetic field generating unit  6  can be loaded into and unloaded from the circular tube  33 B through the tube opening on the flange  36  side, instead of the tube opening on the flange  35  side, by separating the partition wall  39  from the flange  36 . An inspection hole may be appropriately formed on the tube wall of the circular tube  33  so that an operator can check from the outside of the circular tube  33  whether or not the magnetic field generating unit  6  is stored in a predetermined position in the circular tube  33 . The inspection hole is closed while the apparatus is being used. 
     As described above, the circular tubes  33 A and  33 B forming the housing  31  are separable, and the circular tubes  33 A and  33 B and the magnetic field generating unit  6  can be attached/detached by relative movement in the tube axis direction through the tube openings of the circular tubes  33 A and  33 B. Therefore, even if the tube diameters of the circular tubes  33 A and  33 B are relatively small, the maintenance of the magnetic field generating unit  6  and the transfer body  61  and the fabrication of the vacuum transfer module  3  can be easily performed. Further, since the wheels  69  for guiding such relative movement are provided, the attachment/detachment operation can be easily performed. 
     The guide member for guiding such relative movement is not limited to a rolling body such as the wheels  69 . For example, a guide rail (referred to as “one guide rail”) extending along the bottom surface of the floor plate  65  is formed, and a guide rail (referred to as “another guide rail”) extending along the tube axis P on the inner circumferential surface of the circular tube  33  is formed. One guide rail and another guide rail may be engaged with each other so that they can slide along the lengthwise direction of the guide rails. 
       FIG.  10    shows an example in which a cooling device  16  for temperature control is disposed in the upper space  51 . The cooling device  16  is formed in a horizontal plate shape, and has a channel for fluid therein. The cooling device  16  is connected to a downstream end of a supply line  17 A for supplying fluid to the channel and an upstream end of a discharge line  17 B for discharging fluid from the channel. The upstream end of the supply line  17 A and the downstream end of the discharge line  17 B are connected to a chiller  18  having a pump and a fluid temperature control mechanism. The channels in the chiller  18 , the supply line  17 A, the discharge line  17 B, and the cooling device  16  constituting the temperature controller form a fluid circulation path. The fluid having a preset temperature is supplied to the channel of the cooling device  16 , so that a cooling surface  19  that is the bottom surface of the cooling device  16  is set to the preset temperature. The preset temperature is lower than the processing temperature of the wafer Win each processing module  7 . The cooling surface  19  is disposed above the magnetic field generating surface  67  to face the magnetic field generating surface  67 . 
     When the transfer body  61  unloads the wafer W from the processing module  7 , the transfer body  61  moves to a position where the surface of the wafer W faces the cooling surface  19  with a gap therebetween, as shown in  FIG.  10   . Accordingly, heat is exchanged between the wafer W and the cooling surface  19 . In other words, the wafer W is radiatively cooled by the cooling surface  19 . The transfer body  61  stands by for a predetermined period of time at a position where the wafer W faces the cooling surface  19 , so that the cooled wafer W is transferred to a next transfer destination (the processing module  7  or the load-lock module  25  for performing next processing). By providing the cooling device  16 , it is possible to more reliably prevent the temperature around the vacuum transfer module  3  from increasing. 
     In the configuration example of the vacuum transfer module  3 , the heat shield plate  14  extends in the +Y direction and the −Y direction from the cooling device  16 , and the region below the heat shield plate  14  and the cooling device  16  serves as the transfer region  15  for the wafer W. Therefore, unlike the configuration example described with reference to  FIG.  2    and the like, in the configuration example shown in  FIG.  10   , a part of the heat shield plate  14  is replaced with the cooling device  16 . Alternatively, the entire heat shield plate  14  may be replaced with the cooling device  16 . In other words, the temperature controller  5  may be formed to extend from one end to the other end in the Y direction of the upper space  51  without providing the heat shield plate  14 . More specifically, the heat shield plate  14  is made of a material having relatively high thermal reflectivity, such as aluminum, ceramic, or the like. In the example shown in  FIG.  10   , a heat shield plate  59  is disposed to cover the floor plate  65  from the top. The heat shield plate  59  is made of the same material as that of the heat shield plate  14 , so that the upper surface of the heat shield plate  59  has thermal reflectivity higher than that of the upper surface of the floor plate  65 . Due to the action of the heat shield plate  59 , the radiant heat from the wafer W on the transfer body  61  can be blocked, which makes it possible to more reliably prevent the temperature around the vacuum transfer module  3  from increasing. In this example, the magnetic field is formed on the heat shield plate  59  while transmitting the heat shield plate  59 . Therefore, the upper surface of the heat shield plate  59  corresponds to the magnetic field generating surface from which the transfer body  61  floats. Also in the embodiment described with reference to  FIG.  1    and the like, the heat shield plate  59  can be provided as in the example of  FIG.  10   . 
     The vacuum transfer module  3  may be provided with a cleaning mechanism for removing foreign substances adhered to the inner wall of the housing  31 . The cleaning is performed in a state where the housing  31  is maintained in a vacuum atmosphere while the wafer W is not being transferred by the vacuum transfer module  3 . The cleaning mechanism may have various configurations to be described below. In the following description, the period in which cleaning is performed may be referred to as “cleaning period” and the period in which cleaning is not performed and the wafer W can be transferred may be referred to as “normal period.” 
     The cleaning mechanism may be a gas supply mechanism for supplying a gas during the cleaning period in a different manner from that in the normal period. Specifically, for example, a line system is configured such that the cleaning gas can be injected, instead of N 2  gas, from the gas nozzles  53  during the cleaning period. More specifically, lines that connects the cleaning gas supply source and the gas nozzles  53 , and the flow rate controllers  55  disposed in the lines are provided as the gas supply mechanism forming the cleaning mechanism, and the N 2  gas and the cleaning gas can be selectively supplied from the gas nozzles  53 . The cleaning gas is different from N 2  gas. For example, the cleaning gas is highly clean air referred to as “clean dry air.” By supplying the cleaning gas to the wall surface of the housing  31 , the foreign substances adhered to the wall surface of the housing  31  are peeled off and removed through the exhaust ports  56 . 
     The flow rate of the gas injected during the cleaning period may be greater than the flow rate of the gas injected during the normal period. In the case of injecting N 2  gas from the gas nozzles  53  at the first flow rate or the second flow rate during the normal period as described above, the cleaning gas is injected at a third flow rate greater than the first flow rate and the second flow rate from the gas nozzles  53 . 
     The type of gas used in the normal period and the type of gas used in the cleaning period may be the same. In other words, N 2  gas may be injected at the third flow rate during the cleaning period. In the case of changing the flow rate of N 2  gas between the normal period and the cleaning period, the flow rate controller  55  serves as the gas supply mechanism forming the cleaning mechanism. Further, in the case of switching the gas to be supplied into the housing  31  between N 2  gas and the cleaning gas, the gases are injected from the gas nozzles  53  in the above description. However, a dedicated gas nozzle for the cleaning gas may be formed at the housing  13  so that the cleaning gas can be injected from the dedicated gas nozzle. 
     The cleaning mechanism may supply cleaning liquid into the housing  31 .  FIG.  11    shows a configuration example of the vacuum transfer module  3  to which the cleaning liquid supply mechanism is applied. Some components such as the exhaust ports  56 , the heat shield plate  14 , and the like are not illustrated to avoid complicated illustration. For example, a plurality of cleaning liquid nozzles  72  are arranged above the joint circular tube  32  at intervals in the Y direction, and inject cleaning liquid supplied from a cleaning liquid supply source  73 . The cleaning liquid nozzles  72  and the cleaning liquid supply source  73  constitute the cleaning mechanism (cleaning liquid supply mechanism). Liquid that is unlikely to volatilize in a vacuum atmosphere is appropriately selected as the cleaning liquid. 
     The cleaning liquid injected from the cleaning liquid nozzle  72  is supplied to the portion forming the upper space  51  on the inner circumferential surface of the joint circular tube  32  and flows downward along the portion. The cleaning liquid flows to the portion forming the lower space  52  on the inner circumferential surface of the joint circular tube  32  through the communication path  50 , and then flows toward the bottom portion of the joint circular tube  32 . In this example, the cleaning liquid nozzles  72  are arranged at intervals in the Y direction. The dashed arrows in  FIG.  11    indicate the flow of the cleaning liquid. 
     The joint circular tube  32  shown in  FIG.  11    is supported by the columns  11  and inclined such that the +Y side (one end side in the tube axis direction) becomes lower than the −Y side (the other end side in the tube axis direction). Therefore, the tube axis P indicated by the dashed dotted line extends in the lateral direction, but is inclined with respect to a horizontal plane L indicated by the solid line. The inclination of the tube axis P is intended to allow the cleaning liquid on the bottom portion of the joint circular tube  32  to flow along the inner circumferential surface of the joint circular tube  32  toward the +Y side in the case of injecting the cleaning liquid toward a drain port  74  to be described later. The inclination is intentionally formed to allow the cleaning to flow, and can be avoided in manufacturing the apparatus. An angle θ between the tube axis P and the horizontal plane L is set to be greater than or equal to 3° and smaller than or equal to 10°, for example. The magnetic field generating surface  67  of the floor plate  65  is horizontal as in the above-described examples, so that high transfer accuracy of the transfer body  61  can be achieved. 
     The drain port  74  is opened at the bottom portion on the +Y side of the joint circular tube  32 , and a drain line  75  is connected to the drain port  74 . Further, valves  76  and  77  are sequentially interposed in the drain line  75  toward the downstream side, and the downstream end of the drain line  75  is connected to a drain passage (not shown) maintained in an atmospheric atmosphere. During the cleaning period, the opening/closing of the valves  76  and  77  is controlled such that only one of them is opened. Hereinafter, the opening/closing of the valves  76  and  77  will be described in detail. First, the valve  77  is closed while the valve  76  is opened, and the cleaning liquid stays in a portion between the valves  76  and  77  in the drain line  75 . Then, the valve  76  is closed in a state where the valve  77  is opened, and the cleaning liquid in that portion is discharged to the drain passage. 
     The cleaning may be performed after the entire housing  31  is filled with the cleaning liquid. During the cleaning period in which the cleaning is performed using the cleaning liquid supply mechanism, the valve constituting the exhaust amount controller  47  is closed to prevent the cleaning liquid from being supplied to the exhaust mechanism  48  that is a vacuum pump through the exhaust port  56 . Further, the injection of N 2  gas from the gas nozzles  53  is also stopped. 
     In the vacuum transfer module  3  in which the cleaning liquid supply mechanism is applied as a cleaning mechanism, the housing  31  is formed by the circular tube  33 , so that the cleaning liquid supplied to the inner circumferential surface of the circular tube  33  flows due to its own weight to the bottom portion of the housing  31  where the drain port  74  is opened along the inner circumferential surface of the circular tube  33 . Therefore, it is possible to quickly remove the cleaning liquid from the housing  31  after the cleaning is completed. Further, as described above, in the example shown in  FIG.  11   , the joint circular tube  32  is disposed such that the tube axis P is inclined. Hence, the cleaning liquid flows toward the drain port  74  and is removed, so that the cleaning liquid can be removed more quickly. 
     A mechanism for ultrasonically vibrating the housing  31  may be provided as the cleaning mechanism. The ultrasonic vibration mechanism includes a vibrator and an oscillator that supplies a power to the vibrator. The vibrator is disposed outside the housing  31  or at the columns  11  supporting the housing  31  to vibrate the housing  31  during the cleaning period. The foreign substances adhered to the inner wall surface of the housing  31  are peeled off therefrom due to the vibration, and flow into the exhaust port  56  by the exhaust flow in the housing  31  to be removed. It is also possible to use both the cleaning performed by the ultrasonic vibration mechanism and the cleaning performed by the gas supply mechanism or the cleaning liquid supply mechanism. 
     Next, the differences between the vacuum transfer module  3  and a vacuum transfer module  3 A that is a modification of the vacuum transfer module  3  will be mainly described with reference to the longitudinal cross-sectional view of  FIG.  12   . An outer tube  81  that is a circular tube is disposed to surround the joint circular tube  32  of the vacuum transfer module  3 A. The length of the outer tube  81  is greater than that of the joint circular tube  32 . The tube axis of the outer tube  81  coincides with the tube axis P of the joint circular tube  32 . Therefore, the outer tube  81  and the joint circular tube  32  form a double tube, and the joint circular tube  32  serves as an inner tube. More specifically, the tube axis of the outer tube  81  overlaps the tube axis P. In other words, the outer tube  81  and the joint circular tube  32  are coaxial. 
     The joint circular tube  32  has the same inner configuration as that of the vacuum module  3 , so that the magnetic field generating unit  6  is disposed inside the joint circular tube  32 . The inner circumferential surface of the outer tube  81  and the outer circumferential surface of the joint circular tube  32  are separated from each other with a cylindrical gap  82  interposed therebetween. Although not shown, the joint circular tube  32  is locally supported on the inner circumferential surface of the outer tube  81  via support members. One end of the outer tube  81  in the axial direction is connected to the load-lock module  25 , and the opening of the other end in the axial direction of the outer tube  81  is closed by a partition wall (not shown) so that the gap  82  becomes a sealed space. Therefore, in this example, the circular tube includes the outer tube  81  and the joint circular tube  32 , and the outer tube  81  and the partition wall that closes the end of the outer tube constitute the housing of the vacuum transfer module  3 A. 
     Openings  83  are opened on the sidewall of the outer tube  81  to overlap the openings  37  of the joint circular tube  32 . The side tubes  34  are disposed, instead of the joint circular tube  32 , on the outer circumferential surface of the outer tube  81  and extend from the periphery of the openings  83  in the X direction. The flanges  38  at the ends of the side tubes  34  are connected to the gate valves  71 , similarly to the flanges  38  in the vacuum transfer module  3 . With this configuration, the gap  82  is also maintained in a vacuum atmosphere by exhausting the joint circular tube  32 . 
     In the vacuum transfer module  3 A, even if the joint circular tube  32  is heated by the radiant heat from the wafer W unloaded from the processing module  7 , the heating of the outer tube  81  via the joint circular tube  32  is suppressed because the joint circular tube  32  and the outer tube  81  are in local contact with each other as described above and the gap  82  provides a vacuum insulation effect. Therefore, in the vacuum transfer module  3 A, an increase in an ambient temperature is suppressed. Although the vacuum transfer module  3 A illustrated in  FIG.  12    is not provided with the heat shield plate  14  and the cooling device  16  for suppressing an increase in an ambient temperature outside the module, they may be provided to further suppress an increase in an ambient temperature. 
     Since the outer tube  81  is formed as a circular tube similarly to the joint circular tube  32 , the vacuum transfer module  3 A also exhibits the effect obtained when the housing does not have corner portions, which has been described in the case of the vacuum transfer module  3 . 
     Next, a substrate processing apparatus  8  shown in  FIG.  13    will be described. In the substrate processing apparatus  8 , two substrate processing apparatuses  1  described above are arranged side by side in the X direction. The vacuum transfer modules  3  of the two substrate processing apparatuses  1  are connected to each other through a vacuum transfer module  3 B having the same configuration as that of the vacuum transfer module  3 . The two substrate processing apparatuses  1  will be referred to as “substrate processing apparatus  1 A” and “substrate processing apparatus  1 B” for convenience. 
     The vacuum transfer module  3 B and the vacuum transfer module  3  are different in that both ends of the joint circular tube  32  extend in the X direction, and the tube openings that are opened in the X direction are blocked by the partition walls  39 . Two side tubes  34  are spaced apart from each other in the X direction and directed toward the +Y side. 
     In the vacuum transfer modules  3  of the substrate processing apparatuses  1 A and  1 B, the flanges  36  on the +Y side are not provided with the partition walls  39 , and connected to the flanges  38  of the side tubes  34  of the vacuum transfer module  3 B. Further, the floor plates  65  of the substrate processing apparatuses  1 A and  1 B extend into the housing  31  of the vacuum transfer module  3 B and connected to the floor plate  65  of the vacuum transfer module  3 B. Since the floor plates  65  are connected, the transfer body  61  can move between the housing  31  of the substrate processing apparatus  1 A and the housing  31  of the substrate processing apparatus  1 B via the vacuum transfer module  3 B. Therefore, the substrate processing apparatus  8  is not required to transfer the wafer W to the atmospheric atmosphere in the case of sequentially transferring and processing the wafer W between the processing modules  7  of the substrate processing apparatus  1 A and the processing modules  7  of the substrate processing apparatus  1 B. 
     Although the case in which a conventional circular tube can be as the circular tube  33  of the substrate processing apparatus  1  ( 1 A and  1 B) has been described, it is possible to use a conventional circular tube that complies with a predetermined standard. Therefore, in the vacuum transfer module  3 A, the flanges  38  of the side tubes  34  connected to the circular tube  33  may be flanges that comply with the corresponding standard. Therefore, the fabrication of the vacuum transfer module  3 B can be facilitated. In other words, since the housing  31  of the vacuum transfer module  3  is formed by the circular tube  33 , it is possible to facilitate the fabrication of not only the housing  31  but also the modules connected thereto. Hence, the fabrication of the apparatus in which the apparatuses including the vacuum transfer modules  3  are connected to each other as illustrated in  FIG.  13    can also be facilitated. 
     Although the case in which the circular tube  32  forming the housing  31  includes the two circular tubes  33 A and  33 B connected in the tube axis directions was illustrated, the housing  31  may be formed by a single circular tube, or may be formed by connecting three or more circular tubes in the tube axis direction. When a plurality of circular tubes are joined as in the case of the joint circular tube  32 , the joined circular tube may be considered as one circular tube. Therefore, one side tube  34  (substrate transfer path) is disposed at each of the circular tubes  33 A and  33 B forming the joint circular tube  32 . In that case, the circular tube has not a single but multiple substrate transfer paths, and the multiple transfer paths are formed at different positions in the tube axis direction. 
     Next, a vacuum transfer module  3 C shown in  FIG.  14    will be described. The vacuum transfer module  3 C is different from the vacuum transfer module  3  in that two floor plates  65  are disposed at one circular tube  33 , and the two floor plates  65  are arranged in a V shape when viewed in the axial direction. More specifically, the magnetic field generating surface  67  of one of the two floor plates  65  rises from the center of the circular tube  33  toward the left side when viewed in the tube axis direction, and the magnetic field generating surface  67  of the other floor plate  65  rises from the center of the circular tube  33  toward the right side when viewed in the tube axis direction. The two magnetic field generating surfaces  67  are inclined in different directions with respect to the horizontal plane and form a first inclined surface and a second inclined surface, respectively. 
     The transfer body  61  is provided for each magnetic field generating surface  67 . In other words, two transfer bodies  61  move in a floating state in the plane direction with respect to the magnetic field generating surface  67  forming the first inclined surface and the magnetic field generating surface  67  forming the second inclined surface. In the vacuum transfer module  3 C, the power is supplied such that some of the coils  66  of the floor plate  65  exert a repulsive action on the magnets  64  of the transfer bodies  61 , and some other coils exert an attracting action on the magnets  64  of the transfer bodies  61 . By maintaining the balance between the repulsive action and the attracting action, the transfer bodies  61  can move in the plane direction of the magnetic field generating surfaces  67  while being spaced apart from the magnetic field generating surfaces  67  that are inclined surfaces. The magnetic field generating surfaces  67  are inclined to a degree that prevents the wafers W from falling off the transfer bodies  61 . With this configuration, the transfer operations can be performed simultaneously using the two transfer bodies  61  (the first transfer body and the second transfer body), thereby improving the throughput while avoiding scaling up of the circular tube  33 . 
     Next, a vacuum transfer module  3 D shown in  FIG.  15    will be described. In this example, a plurality of magnetic field generating plates  80  forming the floor plate  65  are arranged to cover the inner circumferential surface of the circular tube  33 . The magnetic field generating surfaces  67  of the magnetic field generating plates  80  face the tube axis P. By providing the magnetic field generating plates  80  as described above, the magnetic field generating surfaces  67  of the magnetic field generating plates  80  are formed as curved surfaces. The magnetic field generating surfaces  67  are entirely formed in a circular tube shape, and the region on the inner surface of the circular tube serves as the transfer region  15  for the wafer W. In other words, the transfer region  15  is also formed in a circular tubular shape. Further, by providing the magnetic field generating plates  80  as described above, the inner circumferential surface of the circular tube including the circular tube  33  and the magnetic field generating plates  80  serves as the magnetic field generating surface  67 . 
     Also in the vacuum transfer module  3 D, the balance between the repulsive action and the attracting action is maintained, so that the transfer body  61  can move in the plane direction of the magnetic field generating surface  67  while being separated from the magnetic field generating surface  67 . In other words, the transfer body  61  can move both in the circumferential direction and in the axial direction on the magnetic field generating surface  67  forming the circular tube. Although only one transfer body  61  is shown in  FIG.  15   , a plurality of transfer bodies  61  may be provided and moved without interference with each other. The transfer body  61  supporting the wafer W moves in a state where the supporting surface of the wafer W faces upward to prevent the wafer W from falling. On the other hand, the transfer body  61  that is not supporting the wafer W may move in a state where the support surface faces upward or downward or sideward. The circular tube  33  may not be provided in the vacuum transfer module  3 D. In other words, only the magnetic field generating plate  80  may form the circular tube. 
     In the apparatus such as the substrate processing apparatus  1  or the like, the transfer body  61  moves in the housing  31  maintained in a vacuum atmosphere. However, the transfer body  61  may move in the housing  31  maintained in an atmospheric atmosphere. When the housing  31  is maintained in an atmospheric atmosphere, the processing module  7  connected to the housing  31  and to which the wafer W is delivered by the transfer body  61  may also be maintained in an atmospheric atmosphere. The substrate as a transfer target of the present disclosure is not limited to a circular substrate, and may be a rectangular substrate. Further, the configuration in which the circular tube forming the housing  31  has a tube wall having a perfect circular shape when viewed in the tube axis direction has been illustrated, a tube may have an elliptical shape. In addition, although the case of supplying N 2  gas into the housing  31  has been described, the present disclosure is not limited thereto, and any other inert gas such as argon or the like can also be used. 
     The embodiments of the present disclosure are considered to be illustrative in all respects and not restrictive. The above-described embodiments may be omitted, replaced, changed and/or combined in various forms without departing from the scope of the appended claims and the gist thereof. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.