Patent Publication Number: US-2023143372-A1

Title: Substrate transfer apparatus and substrate transfer method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2021-180835 filed on Nov. 5, 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 
     For example, in an apparatus (wafer processing apparatus) for processing a semiconductor wafer (hereinafter, also referred to as “wafer”) that is a substrate, a wafer is transferred between a carrier accommodating wafers and a wafer processing chamber for processing a wafer. Various types of wafer transfer mechanisms are used for transferring wafers. 
     The applicants of the present disclosure are developing a wafer processing apparatus for transferring a substrate using a substrate transfer module that utilizes magnetic levitation. 
     In the wafer processing apparatus, small amounts of various contaminants such as particles generated by the contact between a wafer and a device or between devices, chemical substances used during wafer processing, and the like exist in a space where a wafer is transferred. When these contaminants are adhered to and accumulated on the substrate transfer module, a wafer to be transferred is contaminated. 
     For example, Japanese Laid-open Patent Publication No. 2005-101539 discloses a technique for increasing temperatures of members constituting a stage on which a substrate to be processed is placed and the like in a decompression processing apparatus and scattering particles by thermal stress and thermophoretic force. On the other hand, Japanese Laid-open Patent Publication No. 2005-101539 does not disclose a method for dealing with the contamination of the substrate transfer module that utilizes magnetic levitation. 
     SUMMARY 
     The present disclosure provides a technique for cleaning a substrate transfer module that utilizes magnetic levitation to transfer a substrate. 
     In accordance with one aspect of the present disclosure, an apparatus for transferring a substrate to a substrate processing chamber is provided. The apparatus comprises: a substrate transfer chamber having a floor provided with a first magnet and a sidewall connected to the substrate processing chamber and having an opening through which a substrate is loaded into and unloaded from the substrate processing chamber; a substrate transfer module including a substrate holder configured to hold the substrate and a second magnet having a repulsive force against the first magnet, and configured to move in the substrate transfer chamber by magnetic levitation using the repulsive force; and a heating device configured to heat the substrate transfer module to release contaminants adhered to a surface of the substrate transfer module. 
    
    
     
       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 showing a first configuration example of a wafer processing system; 
         FIG.  2    is a plan view showing a first configuration example of a transfer module; 
         FIG.  3    is a perspective view showing a configuration example of a transfer module and tiles; 
         FIG.  4    is a plan view showing an operation example of the wafer processing system; 
         FIG.  5 A  is a first longitudinal cross-sectional view showing a first configuration example of a heating device; 
         FIG.  5 B  is a second longitudinal cross-sectional view showing the first configuration example of the heating device; 
         FIG.  6    is a longitudinal cross-sectional view showing a second configuration example of the heating device; 
         FIG.  7 A  is a first longitudinal cross-sectional view showing a third configuration example of the heating device; 
         FIG.  7 B  is a second longitudinal cross-sectional view showing the third configuration example of the heating device; 
         FIG.  8    is a longitudinal cross-sectional view showing a fourth configuration example of the heating device; 
         FIG.  9    is a plan view showing a second configuration example of the wafer processing system; 
         FIG.  10    is a plan view showing a second configuration example of the transfer module; 
         FIG.  11    is a plan view showing a third configuration example of the wafer processing system; and 
         FIG.  12    is a block diagram showing a configuration example of a mechanism for correcting positional displacement caused by heating of the transfer module. 
     
    
    
     DETAILED DESCRIPTION 
     &lt;Wafer Processing System&gt; 
     Hereinafter, a configuration of an apparatus for transferring a substrate according to an embodiment of the present disclosure will be described with reference to  FIG.  1   . The apparatus for transferring a substrate is disposed in a wafer processing system  101 . 
       FIG.  1    shows the multi-chamber type wafer processing system  101  including a plurality of wafer processing chambers  110  that are substrate processing chambers for processing wafers W. As shown in  FIG.  1   , the wafer processing system  101  includes load ports  141 , an atmospheric transfer chamber  140 , load-lock chambers  130 , a vacuum transfer chamber  160 , and the plurality of wafer processing chambers  110 . In the following description, a side on which the load ports  141  are arranged is set to a front side. 
     In the wafer processing system  101 , the load ports  141 , the atmospheric transfer chamber  140 , the load-lock chambers  130 , and the vacuum transfer chamber  160  are arranged in a horizontal direction in that order from the front side. The plurality of wafer processing chambers  110  are arranged side by side on the left and right sides of the vacuum transfer chamber  160  when viewed from the front side. 
     Each of the load ports  141  is configured as a placing table on which a carrier C accommodating wafers W to be processed is placed. Four load ports  141  are arranged side by side in the left-right direction when viewed from the front side. A front opening unified pod (FOUP) or the like can be used as the carrier C, for example. 
     The atmospheric transfer chamber  140  has an atmospheric pressure (normal pressure) atmosphere. For example, downflow of clean air is formed in the atmospheric transfer chamber  140 . A wafer transfer mechanism  142  for transferring the wafer W is disposed in the atmospheric transfer chamber  140 . The wafer transfer mechanism  142  in the atmospheric transfer chamber  140  is configured as a multi joint arm, for example. The wafer transfer mechanism  142  transfers the wafer W between the carriers C and the load-lock chambers  130 . An alignment chamber (not shown) for alignment of the wafer W is disposed on the left side of the atmospheric transfer chamber  140 , for example. 
     Two load-lock chambers  130 , for example, are arranged side by side between the vacuum transfer chamber  160  and the atmospheric transfer chamber  140 . Each of the load-lock chambers  130  has lift pins  131  for lifting and holding the wafer W loaded thereinto. For example, three lift pins  131  configured to be raised and lowered are disposed at equal intervals along a circumferential direction. Lift pins  113  and  143  to be described later have the same configuration. 
     The inner atmospheres of the load-lock chambers  130  can be switched between an atmospheric pressure atmosphere and a vacuum atmosphere. The load-lock chambers  130  and the atmospheric transfer chamber  140  are connected through gate valves  133 . Further, the load-lock chambers  130  and the vacuum transfer chamber  160  are connected through gate valves  132 . 
     The vacuum transfer chamber  160  corresponds to the substrate transfer chamber of the present disclosure. As shown in  FIG.  1   , the vacuum transfer chamber  160  is configured as a rectangular housing elongated in a forward-backward direction in plan view. The vacuum transfer chamber  160  is evacuated to a vacuum atmosphere by a vacuum exhaust mechanism (not shown). Further, an inert gas supply device (not shown) for supplying an inert gas (e.g., nitrogen gas) may be connected to the vacuum transfer chamber  160  and constantly supply the inert gas into the vacuum transfer chamber  160  that has been decompressed. In the wafer processing system  101  shown in the example of  FIG.  1   , four wafer processing chambers  110  are connected to the right sidewall of the vacuum transfer chamber  160  through gate valves  111 , and other four wafer processing chambers  110  are connected to the left sidewall of the vacuum transfer chamber  160  through other gate valves  111 . The wafers W are loaded and unloaded between the vacuum transfer chamber  160  and the wafer processing chambers  110  through openings that are opened and closed by the gate valves  111 . 
     Each wafer processing chamber  110  is evacuated to a vacuum atmosphere by a vacuum exhaust mechanism (not shown). A placing table  112  is disposed in each wafer processing chamber  110 , and the wafer W is placed on the placing table  112  and subjected to predetermined processing. The processing to be performed on the wafer W may include etching, film formation, cleaning, ashing, or the like. 
     For example, in the case of performing processing while heating the wafer W, the placing table  112  is provided with a heater. When the processing to be performed on the wafer W uses a processing gas, the wafer processing chamber  110  is provided with a processing gas supply device including a shower head or the like. The illustration of the heater and the processing gas supply device is omitted. Further, the placing table  112  is provided with the lift pins  113  for transferring the wafer W to be loaded/unloaded. The wafer processing chamber  110  corresponds to the substrate processing chamber of the present embodiment. 
     &lt;Transfer Module  30 &gt; 
     In the vacuum transfer chamber  160  configured as described above, the wafer W is transferred using the magnetic levitation type transfer module (substrate transfer module)  30 . The transfer module  30  shown in the example of  FIGS.  2  and  3    includes a main body  31  having a rectangular shape in plan view. The main body  31  is provided with an arm portion  32  for holding the wafer W horizontally. The arm portion  32  is disposed to extend in the horizontal direction from a base end portion on the main body  31  side. A fork is disposed at a tip end of the arm portion  32  to surround a region where three lift pins  131  and  113  are disposed from both sides thereof. The fork corresponds to a substrate holder in the transfer module  30 . 
     The arm portion  32  has a length that allows the wafer W to be transferred onto the placing table  112  when the main body  31  is located in the vacuum transfer chamber  160  and the arm portion  32  enters the wafer processing chamber  111  by opening the gate valve  111 . 
     Module-side magnets  33  are disposed in the main body  31  of the transfer module  30 . A configuration example thereof will be described later with reference to  FIG.  3   . 
     &lt;Magnetic Levitation Mechanism&gt; 
     As schematically shown in  FIG.  3   , a plurality of tiles (moving tiles)  10  are disposed on the floor of the vacuum transfer chamber  160 . The tiles  10  are disposed in the movement area of the transfer module  30  that extends from the position (position facing the load-lock chambers  130 ) where the wafer W is transferred to and from the external atmospheric transfer chamber  140  to the front side of the wafer processing chamber  110 . When the transfer area is set such that the transfer module  30  enters the load-lock chamber  130  or the wafer processing chamber  110  and moves therein, the tiles  10  are also disposed on the floor of the load-lock chamber  130  or the wafer processing chamber  110 . 
     A plurality of moving surface-side coils  11  are arranged in each tile  10 . The moving surface-side coils  11  generates a magnetic field when a power is supplied from a power supply device (not shown). The moving surface-side coils  11  correspond to first magnets of the present disclosure. 
     On the other hand, the plurality of module-side magnets  33  that are permanent magnets, for example, are arranged in the transfer module  30 . A repulsive force (magnetic force) acts against the module-side magnets  33  by the magnetic field generated by the moving surface-side coils  11 . Accordingly, the transfer module  30  can be magnetically levitated with respect to the moving surface on the upper surface side of the tile  10 . The module-side magnets  33  disposed in the transfer module  30  correspond to second magnets of the present disclosure. 
     The tile  10  can change the magnetic field state by adjusting the position where the magnetic field is generated or the strength of the magnetic force using the moving surface-side coils  11 . By controlling the magnetic field, it is possible to move the transfer module  30  in a desired direction on the moving surface, adjust the levitation distance from the moving surface, and adjust the direction of the transfer module  30 . The magnetic field on the tile  10  side is controlled by selecting the moving surface-side coils  11  to which the power is supplied or by adjusting the magnitude of the power supplied to the moving surface-side coils  11 . 
     The module-side magnets  33  may include coils that receive a power from a battery disposed in the transfer module  30  and function as electromagnets. The module-side magnets  33  may include both a permanent magnet and a coil. 
     In the example shown in  FIGS.  1  and  3   , the length in the short side direction of the rectangular vacuum transfer chamber  160  in plan view allows two transfer modules  30  arranged side by side and holding the wafers W to move without interference. The length in the short side direction of the vacuum transfer chamber  160  of this example is shorter than the length (the entire length of the transfer module  30  holding the wafer W) from the main body  31  to the tip end of the wafer W held by the transfer module  30 . In this example, the wafers W are transferred using the plurality of transfer modules  30  disposed in the vacuum transfer chamber  160 . 
     The vacuum transfer chamber  160  including the transfer module  30  and connected to the wafer processing chambers  110 , which has been described above, corresponds to the substrate transfer apparatus of the present disclosure. 
     &lt;Controller  5 &gt; 
     The wafer processing system  101  includes a controller  5 . The controller  5  is a computer having a CPU and a storage device, and controls individual components of the wafer processing system  101 . The storage device stores a program including a group of steps (commands) for controlling the movement of the transfer module  30 , the operation of the wafer processing chambers  110 , or the like. The program is stored in a storage medium such as a hard disk, a compact disk, a magneto-optical disk, a memory card, a non-volatile memory, or the like, and installed in the computer from the storage medium. 
     &lt;Transfer Operation of Wafer W&gt; 
     Next, an example of an operation of transferring the wafer W in the wafer processing system  101  configured as described above will be described. First, when the carrier C accommodating wafers W to be processed is placed on the load port  141 , a wafer W is taken out from the carrier C by the wafer transfer mechanism  142  in the atmospheric transfer chamber  140 . Then, the wafer W is transferred to the alignment chamber (not shown) and aligned. When the wafer W is taken out from the alignment chamber by the wafer transfer mechanism  142 , the gate valve  133  is opened. 
     When the wafer transfer mechanism  142  enters the load-lock chamber  130 , the lift pins  131  are lifted to receive the wafer W. Then, the wafer transfer mechanism  142  retracts from the load-lock chamber  130 , and the gate valve  133  is closed. The inner atmosphere of the load-lock chamber  130  is switched from an atmospheric pressure atmosphere to a vacuum atmosphere. 
     When the load-lock chamber  130  has a vacuum atmosphere, the gate valve  132  is opened. At this time, in the vacuum transfer chamber  160 , the transfer module  30  stands by near the connection position with the load-lock chamber  130  while facing the load-lock chamber  130 . The transfer module  30  is raised by magnetic levitation using the magnetic field generated by the moving surface-side coils  11  disposed in the tile  10 . 
     Then, as shown in  FIG.  1   , the arm portion  32  of the transfer module  30  enters the load-lock chamber  130  and is positioned below the wafer W supported by the lift pins  131 . The lift pins  131  are lowered to transfer the wafer W to the fork of the arm portion  32 . 
     Next, the arm portion  32  holding the wafer W retracts from the load-lock chamber  130 , and the transfer module  30  retracts to a lateral position of the wafer processing chamber  110  for processing the wafer W. At this time, the main body  31  of the transfer module  30  is moved to the rear end side of the vacuum transfer chamber  160  while passing through the area where the gate valve  111  is located. Accordingly, the tip end side of the arm portion  32  holding the wafer W is disposed at the lateral side of the gate valve  111 . 
     When the tip end side of the arm portion  32  reaches the lateral side of the gate valve  111 , the transfer module  30  retracts and also revolves such that the tip end side of the arm portion  32  faces the gate valve  111 . Then, the gate valve  111  is opened, and the transfer module  30  revolves to transfer the wafer W into the wafer processing chamber  110  and changes its movement direction to the forward direction. 
     As described above, the length in the short side direction of the vacuum transfer chamber  160  is shorter than the entire length of the transfer module  30  holding the wafer W. Even in this case, the wafer W can be transferred from the vacuum transfer chamber  160  into the wafer processing chamber  110  in by the operation of moving the transfer module  30  forward/backward while rotating the transfer module  30 . 
     Next, when the transfer module  30  faces the wafer processing chamber  110 , the transfer module  30  stops rotation and moves straight until the wafer W reaches a position above the placing table  112 . Then, the wafer W is transferred to the placing table  112  and the transfer module  30  retracts from the wafer processing chamber  110 . Then, the gate valve  111  is closed, and the processing of the wafer W is started. 
     In other words, the wafer W placed on the placing table  112  is heated, if necessary, to a preset temperature, and the processing gas is supplied into the wafer processing chamber  110 , if the processing gas supply device is provided. In this manner, desired processing is performed on the wafer W. 
     After the wafer W is processed for a preset period of time, the heating of the wafer W is stopped and the supply of the processing gas is stopped. The wafer W may be cooled by supplying a cooling gas into the wafer processing chamber  110 , if necessary. Then, the wafer W is transferred in the reverse order of the loading operation, and returned from the wafer processing chamber  110  to the load-lock chamber  130 . 
     After the inner atmosphere of the load-lock chamber  130  is switched to the atmospheric pressure atmosphere, the wafer W in the load-lock chamber  130  is taken out by the wafer transfer mechanism  142  in the atmospheric transfer chamber  140  and returned to a predetermined carrier C. 
     &lt;Release of Contaminants&gt; 
     In the wafer processing system  101  configured as described above, particles may be generated by the contact between devices during the opening/closing operation of the gate valves  132  and  111 , for example. In addition, molecules of the processing gas supplied into the wafer processing chamber  110  may enter the vacuum transfer chamber  160  while being adsorbed to the wafer W and then released from the wafer W. The molecules of the processing gas may react with a small amount of moisture that exists in the vacuum transfer chamber  160  or is adsorbed on device surfaces, thereby forming particles or corrosive substances. 
     As will be described later, the vacuum transfer chamber  160  is constantly evacuated, so that the particles or molecules (chemical substances) are discharged to the outside of the vacuum transfer chamber  160 . Some of the particles or chemical substances may be adhered to the surface of the transfer module  30  before they are discharged from the vacuum transfer chamber  160 . 
     The particles or chemical substances adhered to and accumulated on the surface of the transfer module  30  may re-scatter and contaminate the wafer W. As described above, the moisture adsorbed on the device surfaces may react with the chemical substances, thereby forming particles or corrosive substances. Therefore, the wafer processing system  101  of this example includes a mechanism for releasing contaminants such as particles, chemical substances, and moisture adhered to the surface of the transfer module  30 . In the present disclosure, moisture is also included in the concept of “contaminants.” 
     In the wafer processing system  101  illustrated in  FIGS.  1  and  3   , the mechanism for releasing contaminants is disposed in a cleaning area  20  set in the rear end portion of the vacuum transfer chamber  160 . The rear end portion of the vacuum transfer chamber  160  serves as a space where the main body  31  enters in the case of performing the operation of loading/unloading the wafer W into/from the wafer processing chamber  110  located on the rearmost side when viewed from the load ports  141 . 
     A heating device for heating the transfer module  30  to release contaminants from the surface of the transfer module  30  is disposed in the cleaning area  20 . Hereinafter, various configuration examples of the heating device will be described with reference to  FIGS.  5 A to  8   . 
     First Configuration Example of Heating Device: Heating Light Source  411   
       FIGS.  5 A and  5 B  are longitudinal cross-sectional views of the vacuum transfer chamber  160  taken along line A-A′ of  FIG.  4    (the same in  FIGS.  6  to  8   ). 
     As shown in  FIG.  5 A , a plurality of heating light sources  411  as a first configuration example of the heating device of the present disclosure is disposed at a ceiling portion of the vacuum transfer chamber  160  in the cleaning area  20 . In this example, the heating light sources  411  are disposed on the upper surface side of the ceiling portion of the wafer processing system  101  to uniformly irradiate the cleaning area  20  with heating light for heating the surface of the transfer module  30 . Further, the area irradiated with the heating light can be adjusted by selecting the heating light source  411  to which a power is supplied from the power supply device (not shown). 
     The heating light sources  411  may include an infrared lamp such as a halogen lamp, or a light emitting diode (LED) lamp that emits infrared light. Each heating light source  411  may be provided with a lamp shade  412  to control the irradiation direction of the heating light. 
     The heating light sources  411  are arranged on the upper surface side of the ceiling portion of the vacuum transfer chamber  160  via a cover portion  414  and a holding portion  413 . A transmission window  415  made of quartz glass, for example, and transmitting the heating light is disposed between the area where the heating light sources  411  are arranged and the cleaning area  20  set in the vacuum transfer chamber  160 . 
       FIGS.  5 A and  5 B  show an example in which a cooling device for cooling the transfer module  30  heated by the heating light sources  411  to a use temperature. In this example, the cooling device has a configuration in which a channel (temperature control fluid channel  21 ) through which a coolant that is a temperature control fluid flows is formed in the tile  10 . In this case, the upper surface of the tile  10  serves as a contact surface to be in contact with the main body  31 . A coolant supply device  432  for supplying a coolant and stopping the supply of the coolant is connected to the temperature control fluid channel  21 . 
     A heating operation for releasing contaminants from the surface of the transfer module  30  in the wafer processing system  101  configured as described above will be described. 
     When it is required to heat the transfer module  30 , the main body  31  to be processed is moved to the cleaning area  20  and positioned below the heating light sources  411 . In the examples shown in  FIGS.  4 ,  5 A, and  5 B , one transfer module  30  is disposed. However, two transfer modules  30  may be arranged. 
     For example, the main body  31  may be heated after a preset period of time elapses from previous heating, or after a preset number of wafers W are transferred. 
     For convenience of description,  FIG.  4    shows a state in which the transfer module  30  is disposed in the cleaning area  20  when the wafer W is transferred by another transfer module  30  in the vacuum transfer chamber  160 . In practice, it is preferable to heat the transfer module  30  while the wafer W is not being transferred in the vacuum transfer chamber  160 . 
     The period in which the wafer W is not transferred may include a period in which the wafer W is being processed in the wafer processing chamber  110  and there is a sufficient standby time, or a period in which all the wafers W are processed and there is no wafer W in the vacuum transfer chamber  160  or the wafer processing system  101 . 
     After the transfer module  30  (the main body  31 ) is disposed in the cleaning area  20 , the heating light sources  411  in the region facing the main body  31  are turned on in a state where the transfer module  30  is levitated as shown in  FIG.  5 A , and irradiate the heating light. Due to the irradiation of the heating light, the temperature of the surface of the main body  31  increases abruptly from room temperature. At this time, the surface of the main body  31  may be heated to a temperature in the range of 75° C. to 300° C., for example. 
     When the temperatures of the constituent members of the main body  31  or the particles adhered to the surfaces thereof increase abruptly, sudden thermal stress is applied to the main body  31  and, thus, a force that separates the particles from the surface of the main body  31  is applied. The force that separates particles from the surface of the main body  31  is also applied by the thermophoretic effect caused by a large temperature gradient between the surface of the main body  31  and the surrounding atmosphere. The particles adhered to the surface of the wafer W are released by such a force. 
     The chemical substances or moisture adhered to the surface of the wafer W is also decomposed or sublimated/vaporized by the heating of the main body  31 , and released from the surface of the wafer W. 
     The temperature of the bottom surface of the main body  31 , which is not irradiated with the heating light, also increases due to heat conduction from the upper surface. At this time, the heating is performed in a state where the main body  31  is levitated from the floor of the vacuum transfer chamber  160 , so that particles or chemical substances are released from the bottom surface of the main body  31  by the above-described mechanism. 
     The surface of the arm portion  32  connected to the main body  31  also increases due to heat conduction, and particles or chemical substances are released from the surface thereof. 
     The heating light sources  411  may be disposed to irradiate the heating light to the upper surface of the arm portion  32 . Alternatively, after the main body  31  is heated, the arm portion  32  may enter the cleaning area  20  by changing the direction of the transfer module  30  and the main body  31  may be directly heated. 
     Here, as shown in  FIG.  5 A , one end of an exhaust channel  161  constituting an exhaust device for evacuating the vacuum transfer chamber  160  may be opened on the floor of the area where the cleaning area  20  is disposed. When the cleaning area  20  is set in the vacuum transfer chamber  160 , it is considered that the exhaust channel  161  constitutes the exhaust device for exhausting the atmosphere in which the transfer module  30  is heated. 
     Particles or chemical substances (contaminants) released from the surface of the transfer module  30  are discharged to the outside of the vacuum transfer chamber  160  through the exhaust channel  161 . Therefore, the exhaust channel  161  also functions as a contaminant removal device for removing contaminants released from the surface of the transfer module  30 . 
     As described above, when the inert gas is constantly supplied into the vacuum transfer chamber  160 , the supply flow rate of the inert gas may be increased during the heating of the transfer module  30  to facilitate evacuation. In this case, the pressure in the vacuum transfer chamber  160  may increase. Hence, the effect of pressure variation can be avoided by adjusting the processing schedule or the transfer schedule and heating the transfer module  30  during the period in which the wafer W is not transferred. 
     The transfer module  30  is heated for a preset time and the irradiation of the heating light from the heating light sources  411  is stopped when the surface of the main body  31  becomes clean. Then, the coolant is supplied from the coolant supply device  432  to the temperature control fluid channel  21 , and the transfer module  30  is lowered to bring the bottom surface of the transfer module  30  into contact with the tile  10  located in the region to which the coolant is supplied. When the bottom surface of the main body  31  is brought into contact with the surface (contact surface) of the cooled tile  10 , the entire transfer module  30  (the top and bottom surfaces of the main body  31  and the arm portion  32 ) is cooled by heat conduction. Accordingly, even in the vacuum transfer chamber  160  that is being evacuated, the transfer module  30  can be quickly cooled to room temperature, for example, and the transfer of the wafer W can be resumed. 
     If the coolant is supplied to the temperature control fluid channel  21  even during the heating of the transfer module  30 , the scattered contaminants may be attracted and adhered to the surface of the cooled tile  10  by a thermophoretic force. Therefore, the coolant is not supplied during the heating of the transfer module  30  to avoid contamination of the tile  10  and suppress re-contamination of the transfer modules  30  in contact with the tile  10  during the cooling. 
     Second Configuration Example of Heating Device: Induction Coil  421   
       FIG.  6    shows an example in which the induction coil  421  for induction heating is disposed, as a second configuration example of the heating device of the present disclosure, on the upper surface side of the ceiling portion of the vacuum transfer chamber  160 . The induction coil  421  is covered with the cover portion  422 . The induction coil  421  generates a magnetic field in a region below the induction coil  421  in the vacuum transfer chamber  160  by the power supplied from the power supply device (not shown). 
     The upper surface of the main body  31  that faces the induction coil  421  when the main body  31  is disposed in the cleaning area  20  is made of metal. When the power is supplied from the power supply device to the induction coil  421  and a magnetic field is formed in the vacuum transfer chamber  160 , the temperature of the upper surface of the main body  31  increases due to induction heating. The heating temperature of the main body  31  and the release of contaminants (particles or chemical substances) from the surface of the transfer module  30  (the upper and bottom surfaces of the main body  31  and the arm portion  32 ) are the same as those described with reference to  FIG.  5 A . Further, the cooling of the transfer module  30  by the contact with the tile  10  through which the coolant flows after the release of contaminants through the exhaust channel  161  or the release of the contaminants is the same as that described with reference to  FIGS.  5 A and  5 B , so that the redundant description thereof will be omitted. 
     When it is difficult to levitate the transfer module  30  during the heating using the induction coil  421 , the transfer module  30  may be heated while being supported by a plurality of support pins, for example. 
     Third Configuration Example of Heating Device: Heat Exchange Mechanism 
       FIG.  7 A  shows an example in which a heat medium supply device  431  for supplying a heat medium that is a temperature control fluid to the temperature control fluid channel  21  formed in the tile  10  is provided as a heating device. In this case, while the heat medium is being supplied from the heat medium supply device  431 , the surface of the transfer module  30  is heated to a temperature in the range of 75° C. to 300° C. by heat conduction due to the contact between the main body  31  and the upper surface (contact surface) of the tile  10  (see  FIG.  7 A ). The tile  10  in which the temperature control fluid channel  21  is formed or the heat medium supply device  431  corresponds to the heat exchange mechanism of this example. 
     Then, the transfer module  30  is heated for a preset time. When the surface of the main body  31  becomes clean, the heat medium is switched and the transfer module  30  is cooled by supplying the coolant from the coolant supply device  432  (see  FIG.  7 B ). 
     Fourth Configuration Example of Heating Device: Resistance Heating Element  313   
       FIG.  8    shows an example in which the resistance heating element  313  is disposed, as a heating device, in the transfer module  30 . Further, a power supply device for supplying a power to the resistance heating element  313  is disposed in the transfer module  30 . The resistance heating element  313  may be a secondary battery, for example. In this case, the main body  31  may be provided with a plug for connection to an external power source, and the secondary battery may be charged by inserting the plug into a socket. Alternatively, the secondary battery may be charged by wireless power supply. 
     In addition, the power may be directly supplied to the resistance heating element  313  by a plug-socket mechanism or wireless power supply without providing a secondary battery in the main body  31 . In this case, the plug or a power receiving part for wireless power supply corresponds to the power supply device  314 . 
     The resistance heating element  313  and the power supply device  314  correspond to the heating device of this example. 
     The contaminants can be released from the surface of the transfer module  30  by heating the transfer module  30  to a temperature in the range of 75° C. to 300° C. using the above-described resistance heating element  313 . The cooling of the transfer module  30  by the contact with the tile  10  through which the coolant flows is the same as that described in the example of  FIG.  5 B . 
       FIG.  8    shows an example of a technique for removing contaminants released from the transfer module  30  that is different from a technique for discharging contaminants through the exhaust channel  161 . In other words, a contaminant collecting member  22  having therein a coolant channel  221  is disposed at the ceiling portion of the vacuum transfer chamber  160  of this example, for example. The coolant supply device  23  is connected to the coolant channel  221 , so that the coolant that is a temperature control fluid can be supplied to the coolant supply device  23 . 
     Due to the coolant, the temperature of the surface of the contaminant collecting member  22  is adjusted to be lower than the temperature of the transfer module  30  heated by the resistance heating element  313 . The contaminants released from the surface of the transfer module  30  are transferred toward the contaminant collecting member  22  by a thermophoretic force generated by the temperature gradient between the surface of the transfer module  30  and the surface of the contaminant collecting member  22 , and adhered to the surface of the contaminant collecting member  22 . Accordingly, the contaminants released from the transfer module  30  can be removed from the vacuum transfer chamber  160 . The contaminant collecting member  22  corresponds to the contaminant removal device of this example. 
     Here, either one or both of the contaminant removal device using the exhaust channel  161  shown in  FIGS.  5 A to  7 B  and the contaminant removal device using the contaminant collecting member  22  shown in  FIG.  8    may be selected, if necessary, and arranged. On the other hand, in the example shown in  FIG.  5 A,  5 B , or  6 , the heating device (the heating light sources  411  or the induction coil  421 ) is disposed at the ceiling portion of the vacuum transfer chamber  160 . In this case, the contaminant collecting member  22  may be disposed on the sidewall of the vacuum transfer chamber  160 , for example. 
     &lt;Effect&gt; 
     The wafer processing system  101  of the present disclosure provides the following effect. The heating device (the heating light sources  411 , the induction coil  421 , the coolant supply device  432 , the temperature control fluid channel  21 , or the resistance heating element  313  in the main body  31 ) heats the surface of the transfer module  30  that utilizes magnetic levitation to transfer the wafer W. The particles adhered to the surface of the wafer W can be released by the thermal stress and the thermophoretic force generated by the heating. The chemical substance adhered to the surface of the wafer W can be decomposed or sublimated by the heating of the main body  31  and released from the surface of the wafer W. The transfer module  30  can be cleaned by releasing the contaminants adhered to the surface thereof. 
     &lt;Wafer Processing System  101   a&gt;   
     Next, the modification of the location of the cleaning area  20  and the timing of heating a transfer module  30   a  will be described with reference to an example of the wafer processing system  101   a  shown in  FIG.  9   . In  FIGS.  9  to  12    to be described below, like reference numerals will be given to like parts in the wafer processing system  101  and transfer module  30  described with reference to  FIGS.  1  to  8   . 
     In the wafer processing system  101   a  shown in  FIG.  9   , the cleaning areas  20  are located in the load-lock chambers  130  for switching a pressure because the wafer W is loaded/unloaded between the vacuum transfer chamber  160  and the atmospheric transfer chamber  140 . Hence, the wafer processing system  101   a  is different from the wafer processing system  101  shown in  FIGS.  1  and  3    in that the transfer module  30  is heated in the vacuum transfer chamber  160 . 
     In the wafer processing system  101   a , the floors of the wafer processing chambers  110 , the load-lock chambers  130 , and the atmospheric transfer chamber  140  are located at substantially the same height as the floor of the vacuum transfer chamber  160 . The tiles  10  having the moving surface-side coils  11  are also disposed on the floors thereof. Therefore, the transfer module  30   a  can be moved by magnetic levitation in the wafer processing chambers  110 , the load-lock chambers  130 , and the atmospheric transfer chamber  140 . Hence, the wafer processing system  101   a  is different from that of the wafer processing system  101  shown in  FIGS.  1  and  3    in that the arm portion  32  enters the wafer processing chamber  110  or the load-lock chamber  130  to transfer the wafer W. 
     In the atmospheric transfer chamber  140   a  of this example, the lift pins  143  are disposed on the floor thereof, and the wafer W is transferred to and from the wafer transfer mechanism  142  via the lift pins  143 . The atmospheric transfer chamber  140   a  corresponds to “another substrate transfer chamber” of this example. 
     &lt;Heating 1 in the Load-Lock Chamber  130 &gt; 
     In the wafer processing system  101  of this example, the wafer W is transferred by the transfer module  30   a  that does not have the arm portion  32  so that it can easily enter the load-lock chamber  130  or the wafer processing chamber  110 . As shown in  FIG.  10   , in the transfer module  30   a , the wafer W is directly held on the upper surface of the main body  31 . In other words, the main body  31  of the transfer module  30   a  serves as a stage  34  that is a substrate holder on which the wafer W is placed and held. For example, the stage  34  is formed in a flat rectangular plate shape. 
     The transfer module  30   a  enters the wafer processing chamber  110  or the atmospheric transfer chamber  140  to transfer the wafer W to and from the lift pins  113  and  143 . The transfer module  30   a  has slits  341  for transferring the wafer W while avoiding interference with the lift pins  113  and  143 . The slits  341  are formed along the path through which the lift pins  113  and  143  pass when the stage  34  is moved to and from the position below the wafer W held by the lift pins  113  and  143 . The slits  341  are formed such that the direction of the wafer W at the time of moving the stage  34  to the position below the wafer W can be reversed by 180°. Accordingly, the transfer module  30   a  and the wafer W can be arranged concentrically in a vertical direction without interference between the transfer module  30   a  and the lift pins  113  and  143 . 
     In the atmospheric transfer chamber  140  configured as described above, the transfer module  30   a  enters the atmospheric transfer chamber  140   a  via the load-lock chamber  130 , receives an unprocessed wafer W from the lift pins  143 , and transfers a processed wafer W to the lift pins  143 . Although downflow of clean air is formed in the atmospheric transfer chamber  140   a  as described above, a relatively large amount of particles exist in the atmospheric transfer chamber  140   a  compared to the amount of particles in the vacuum transfer chamber  160  maintained in a vacuum atmosphere. In the atmospheric transfer chamber  140   a , moisture tends to be adsorbed on the transfer module  30   a . Further, the chemical substances adhered to the wafer W during the processing in the wafer processing chamber  110  may enter the atmospheric transfer chamber  140   a  and react with moisture in the atmosphere or moisture adsorbed on the transfer module  30   a  to form particles or corrosive chemical substances. 
     When the transfer module  30   a  is moved between the atmospheric transfer chamber  140   a  and the vacuum transfer chamber  160  having different cleanliness levels, contaminants or moisture may enter the vacuum transfer chamber  160  or the wafer processing chamber  110  by the movement of the transfer module  30   a . Therefore, the contaminants are released by heating the transfer module  30   a  in the load-lock chamber  130  when the transfer module  30   a  is moved from the atmospheric transfer chamber  140   a  to the vacuum transfer chamber  160 . In this case, it is preferable that the transfer module  30   a  is not transferring the wafer W. By heating the transfer module  30   a , the transfer module  30   a  having a clean surface can enter the vacuum transfer chamber  160  or the wafer processing chamber  110 . 
     &lt;Heating 2 in the Load-Lock Chamber  130 &gt; 
       FIG.  11    shows a wafer processing system  101   b  in which vacuum transfer chambers  160  and  160   a  having different vacuum levels are connected via the load-lock chambers  130 , and the cleaning areas  20  are located in the load-lock chambers  130 . For example, the wafer processing  110   a  for performing physical vapor deposition (PVD) film formation requires a higher vacuum level compared to the wafer processing chamber  110  for performing chemical vapor deposition (CVD) film formation. Further, for example, the PVD film formation may be performed continuously after the CVD film formation. Therefore, in the wafer processing system  101   b  shown in  FIG.  11   , the CVD film formation and the PVD film formation can be consecutively performed by connecting the first vacuum transfer chamber  160  connected to the wafer processing chamber  110  for CVD and the second vacuum transfer chamber  160   a  connected to the wafer processing chamber  110   a  for PVD via the load-lock chambers  130 . 
     On the other hand, the second vacuum transfer chamber  160   a  connected to the wafer processing chamber  110   a  for PVD film formation that requires a high vacuum level may require a higher cleanliness level compared to that in the first vacuum transfer chamber  160 . Thus, in the wafer processing system  101   b  of this example, the cleaning areas  20  are located in the load-lock chambers  130  arranged between the first vacuum transfer chamber  160  and the second vacuum transfer chamber  160   a . With this configuration, when the transfer module  30   a  is moved from the first vacuum transfer chamber  160  to the second vacuum transfer chamber  160   a , the transfer module  30   a  can be heated in the load-lock chamber  130  and the contaminants can be released. In this case, it is preferable that the transfer module  30   a  is not transferring the wafer W. The transfer module  30   a  having a clean surface by heating the transfer module  30   a  can enter the second vacuum transfer chamber  160   a  or the wafer processing chamber  110   a  for performing PVD film formation. 
     The first vacuum transfer chamber  160  and the second vacuum transfer chamber  160   a  have substantially the same configuration except that they have different wafer processing chambers  110  and  110   a  connected to openings. Further, the processing of the wafer Win the wafer processing chambers  110  and  110   a  connected to the first and second vacuum transfer chambers  160  and  160   a  is not limited to a combination of PVD film formation and CVD film formation. For example, it is possible to perform an etching process in the wafer processing chamber  110   a  connected to the second vacuum transfer chamber  160   a  having a high vacuum level, and then perform the CVD film formation in the wafer processing chamber  110  connected to the first vacuum transfer chamber  160  having a low vacuum level. 
     In  FIG.  11   , the illustration of the load-lock chambers  130  arranged between the first vacuum transfer chamber  160  and the atmospheric transfer chamber  140   a  is omitted. Similarly to the wafer processing system  101   a  shown in  FIG.  9   , the cleaning areas  20  may be located in the load-lock chambers  130 , and the transfer module  30   a  may be heated. 
     Referring to  FIG.  11   , the wafer processing chamber  110  may be connected to a transfer chamber maintained in an atmospheric atmosphere instead of the first vacuum transfer chamber  160 . In this case, the second vacuum transfer chamber  160   a  is connected to the transfer chamber maintained in an atmospheric atmosphere through the load-lock chambers  130  where the cleaning areas  20  are located. 
     In the wafer processing systems  101   a  and  101   b  according to the examples of  FIGS.  9  and  11   , the heating device disposed in the cleaning area  20  may be any one of the heating light sources  411 , the induction coil  421 , the coolant supply device  432  and the temperature control fluid channel  21 , and the resistance heating element  313  in the main body  31  described with reference to  FIGS.  5 A to  8   . Further, the cooling device (the coolant supply device  432 , the temperature control fluid channel  21 , or the like) of the transfer module  30   a  may be disposed on the floors of the load-lock chambers  130 . In addition, the exhaust device for exhausting the load-lock chambers  130  or the contaminant collecting member  22  may be provided as the contaminant removal device. When the contaminant removal device serves as the exhaust device, a vacuum exhaust channel for creating a vacuum atmosphere in the load-lock chamber  130  may be used. 
     Also in the wafer processing systems  101   a  and  101   b  of the examples of  FIGS.  9  and  11   , the wafer W may be transferred using the transfer module  30  having the arm portion  32  shown in  FIG.  2   . In this case, the load-lock chambers  130  where the cleaning areas  20  are located have a size that allows the entire transfer module  30  having the arm portion  32  to be accommodated. 
     The heating of the transfer modules  30  and  30   a  is not necessarily performed in the vacuum transfer chamber  160  shown in  FIGS.  1  and  4    or the load-lock chambers  130  shown in  FIGS.  9  and  11   . For example, a dedicated processing chamber for heating the transfer modules  30  and  30   a  may be connected to the rear end of the vacuum transfer chamber  160  through an opening that can be opened and closed by a shutter, and the cleaning areas  20  may be set in the dedicated processing chamber. 
     &lt;Correction of Movement Control&gt; 
     As described above, in each of the wafer processing systems  101 ,  101   a , and  101   b , the contaminants on the surface are released by heating the transfer modules  30  and  30   a  using the heating device (the heating light sources  411 , the induction coil  421 , the coolant supply device  432  and the temperature control fluid channel  21 , or the resistance heating element  313  in the main body  31 ). On the other hand, it is known that the magnetic force of the module-side magnets  33  disposed in the transfer modules  30  and  30   a  decreases due to thermal demagnetization when the module-side magnets  33  are heated. 
     For example,  FIG.  12    shows an example in which the movement of the transfer modules  30  and  30   a  is controlled using the function of a movement controller  501  of the controller  5 . The movement controller  501  moves the transfer modules  30  and  30   a  to target position by selecting the moving surface-side coils  11  to which the power is supplied from the power supply device  53  or by adjusting the magnitude of the power supplied to the moving surface-side coils  11 . 
     When the magnetic force of the module-side magnets  33  in the transfer modules  30  and  30   a  decreases, the repulsive force acting between the moving surface-side coils  11  and the module-side magnets  33  decreases. As a result, even if the moving surface-side coils  11  are selected in a preset order based on a recipe, and the movement control is performed by supplying a preset power to the moving surface-side coils  11 , the transfer modules  30  and  30   a  may not reach the target positions. 
     Therefore, a wafer processing system  101   c  shown in  FIG.  12    includes a position detector  52  for specifying the actual positions of the transfer modules  30  and  30   a  in the vacuum transfer chamber  160 . A sensor for detecting the positions of the transfer modules  30  and  30   a  is disposed in the vacuum transfer chamber  160 , and the position detector  52  specifies the positions of the transfer modules  30  and  30   a  based on the information obtained from the sensor. 
     The position detection sensor may include a plurality of Hall-effect sensors located at preset positions in the tile  10 , a laser displacement meter, and a camera for imaging the positions of the transfer modules  30  and  30   a .  FIG.  12    shows an example in which the plurality of Hall-effect sensors  51  are disposed in the tile  10 . 
     The controller  5  has the function of a displacement amount detector  503 , and detects a positional displacement amount between the actual positions of the transfer modules  30  and  30   a  detected by the position detector  52  and the target positions where the module-side magnets  33  reach when thermal demagnetization does not occur. Since it is considered that the positional displacement amount is caused by thermal demagnetization of the magnetic force of the module-side magnets  33 , the repulsive force between the moving surface-side coils  11  and the module-side magnets  33  controlled by the movement controller  501  is corrected to offset the positional displacement amount using the function of a corrector  502  of the controller  5 . 
     The corrector  502  may correct the repulsive force using linear correction, for example. For example, when it is detected that the levitation heights (the position in the Z direction shown in  FIG.  1   ) of the transfer modules  30  and  30   a  has decreased to 80% of the target heights due to thermal demagnetization, the corrector  502  corrects the control value outputted from the movement controller  501  such that the power supplied from the power supply device  53  to the moving surface-side coils  11  is increased by 1.25 times. 
     When the influence of the heat source increases and, thus, it is difficult to reduce the positional displacement amount even after the correction, an error may be issued by the wafer processing systems  101 ,  101   a  to  101   c . When the error is issued, the original magnetic force may be restored by taking out the transfer modules  30  and  30   a  and magnetizing the module-side magnets  33  at the outside. 
     The embodiments of the present disclosure are illustrative in all respects and are not restrictive. The above-described embodiments may be omitted, replaced, or changed 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.