Patent Publication Number: US-2019189482-A1

Title: Transfer device, transfer method, and inspection system

Description:
TECHNICAL FIELD 
     The present disclosure relates to a transfer device and a transfer method for transferring a target object, and an inspection system. 
     BACKGROUND 
     In the manufacturing process of a semiconductor device, an IC chip formed on a semiconductor wafer is electrically inspected. As an inspection device that performs such electrical inspection, a probe device that performs the electrical inspection by bringing a probe into contact with electrodes of a semiconductor element formed on a semiconductor wafer is generally used. 
     In order to efficiently perform such electrical inspection on a large number of semiconductor wafers, an inspection system has been proposed, in which a plurality of probe devices (inspection devices) is arranged and semiconductor wafers received in a receiving vessel such as an FOUP are transferred to each of the probe devices by a transfer device (for example, Patent Document 1). 
     In order to further improve the efficiency of electrical inspection of semiconductor wafers, recently, there has also been a demand for an inspection system in which as many as 10 to 15 probe devices (inspection devices) are arranged in a horizontal direction. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     
         
         Patent Document 1: Japanese laid-open publication No. 2013-254812 
       
    
     As the number of inspection devices is increased in this way, since a loader performing transferring the wafers in the transfer device that transfers the semiconductor wafers has a moving distance (stroke) of about ten meters at the longest in the horizontal direction, it is technically difficult to apply a ball screw drive or a linear motor drive that are generally used as a driving method. 
     On the other hand, a belt driving method using a timing belt is suitable for transfer of such a long moving distance. 
     However, when the timing belt becomes longer by about ten meters, there is an influence of slackness or elongation, and when controlling the position of the loader, there may be a case where a deviation occurs between the position of the loader based in the coordinate system of a software and the actual position of the loader, making it impossible to accurately transfer the semiconductor wafers as target objects. 
     The present disclosure provides some embodiments of a transfer device and a transfer method capable of transferring a target object at an accurate position even when a belt driving method using a timing belt is adopted, and an inspection system using such a transfer device. 
     SUMMARY 
     According to a first aspect of the present disclosure, there is provided a transfer device, including: a transfer part configured to transfer a target object; a transfer path having a plurality of transfer positions at which the transfer part transfers the target object while moving along one direction; a driving mechanism of a belt driving type configured to move the transfer part along the transfer path by a timing belt arranged in the one direction; a position sensor configured to generate a signal when the transfer part reaches a predetermined position corresponding to each of the transfer positions; and controller configured to control the transfer part, wherein the controller has coordinates of a position of the transfer part, and is configured to correct position data of the transfer part in a coordinate system of the controller based on the signal each time the controller receives the signal from the position sensor. 
     It is preferable that the transfer device further includes a positioning mechanism configured to mechanically position the transfer part at each of the plurality of transfer positions when the transfer part reaches near each of the plurality of transfer positions. 
     The transfer device can be configured to further include a flag installed at the predetermined position corresponding to each of the plurality of transfer positions of the transfer path, wherein the position sensor is installed in the transfer part, and when the position sensor reaches the flag, the signal is generated from the position sensor. 
     The position sensor includes a plurality of position sensors arranged in a direction orthogonal to the one direction. 
     The transfer part is connected to the timing belt via a connection member, and the connection member is connected to an upper end side of the timing belt. The transfer device further includes a cable duct configured to receive cables connected to the transfer part; and a roller part configured to support an upper end side of the cable duct. 
     According to a second aspect of the present disclosure, there is provided a transfer method using a transfer device including a transfer part configured to transfer a target object, a transfer path having a plurality of transfer positions at which the transfer part transfers the target object while moving along one direction, a driving mechanism of a belt driving type configured to move the transfer part along the transfer path by a timing belt arranged in the one direction, a position sensor configured to generate a signal when the transfer part reaches a predetermined position corresponding to each of the transfer positions and a controller configured to control the transfer part, the method including: generating the signal when the transfer part reaches the predetermined position corresponding to each of the plurality of transfer positions; and correcting position data of the transfer part in a coordinate system of the controller based on the signal each time the controller receives the signal from the position sensor. 
     According to a third aspect of the present disclosure, there is provided an inspection system, including: an inspection unit having a plurality of inspection devices arranged in one direction and configured to electrically inspect an target object to be inspected; and a transfer device configured to transfer the target object to the plurality of inspection devices, wherein the transfer device includes: a transfer part configured to transfer the target object to the plurality of inspection devices; a transfer path having a plurality of transfer positions at which the target object is transferred between the transfer part and each of the inspection devices while the transfer part is moved along one direction; a driving mechanism of a belt driving type configured to move the transfer part along the transfer path by a timing belt arranged in the one direction; a position sensor configured to generate a signal when the transfer part reaches a predetermined position corresponding to each of the plurality of transfer positions; and a controller configured to control the transfer part, wherein the controller has coordinates of a position of the transfer part, and is configured to correct position data of the transfer part in a coordinate system of the controller based on the signal each time the controller receives the signal from the position sensor. 
     According to the present disclosure, when the transfer part is moved by a driving mechanism of a belt driving type in which the transfer part is moved using a timing belt along the transfer path having a plurality of transfer positions for transferring the target object by the transfer part by moving the transfer part along one direction, and reaches a predetermined position corresponding to each of the transfer positions, position data of the transfer part in a coordinate system of the controller is corrected based on a signal each time the controller receives the signal generated from the sensor. Therefore, by properly correcting the positional deviation in the moving direction of the transfer part, it is possible to set the transfer position with high accuracy and to perform accurate transfer of the target object. In addition, since the position in the coordinate system of the controller is corrected based on the signals detected by the position sensors at the plurality of transfer positions, the stroke of the transfer part in the moving direction is subdivided, and even if a transfer error occurs, the error does not become large. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view illustrating a schematic configuration of an inspection system according to one embodiment of the present disclosure. 
         FIG. 2  is a perspective view illustrating a driving mechanism in a transfer device of the inspection system in  FIG. 1 . 
         FIG. 3  is a view illustrating a connection state of a timing belt and a connection member in the driving mechanism in  FIG. 2 . 
         FIG. 4  is a side view illustrating an arrangement state of a sensor part and a flag part. 
         FIG. 5  is a cross-sectional view illustrating a positional relationship between position sensors and flags. 
         FIG. 6  is a side view illustrating a cable duct used in the transfer device. 
         FIG. 7  is a block diagram illustrating a controller used in the inspection system in  FIG. 1 . 
         FIG. 8  is a block diagram illustrating a main part of the controller. 
         FIG. 9  is a view illustrating a deviation of a transfer position. 
         FIG. 10  is a flowchart illustrating a flow of position control by a transfer controller. 
         FIG. 11  is an explanatory view illustrating position correction of a transfer position. 
         FIG. 12  is a schematic view illustrating a positioning mechanism. 
         FIG. 13A  is a view illustrating a positioning operation by the positioning mechanism in  FIG. 12 . 
         FIG. 13B  is a view illustrating a positioning operation by the positioning mechanism in  FIG. 12 . 
         FIG. 13C  is a view illustrating a positioning operation by the positioning mechanism in  FIG. 12 . 
         FIG. 14  is a view illustrating slackness of the timing belt. 
         FIG. 15  is a view illustrating a state where a connection member is connected to a lower end side of the timing belt. 
         FIG. 16  is a view illustrating a state of a cable duct when a moving stroke of the loader in an X direction becomes longer. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. 
     &lt;Configuration of the Inspection System&gt; 
       FIG. 1  is a plan view illustrating a schematic configuration of an inspection system according to one embodiment of the present disclosure. The inspection system  100  serves to electrically inspect a semiconductor wafer (hereinafter, simply referred to as a “wafer”) W as an object to be inspected, and includes an inspection unit  10 , a loading/unloading unit  20 , a transfer device  30 , and a controller  40 . 
     The inspection unit  10  has a plurality of, for example, about 10 to 15 inspection devices  11 , which are arranged in an X direction in the drawing. Each of the inspection devices  11  is configured as a probe device, and has a housing and a wafer loading table installed therein, in which a probe card having a plurality of probe needles (contacts) is installed. The wafer loading table is configured to move the wafer loaded thereon in the X, Y, Z and θ directions, and is moved such that the probe needles of the probe card are brought into contact with electrodes of a semiconductor device formed on the wafer to perform electrical inspection of the wafer W by a tester through a test head. 
     The loading/unloading unit  20  has a loading/unloading stage part  21  having a plurality of loading/unloading stages for loading/unloading the wafer W, the probe card or the like, and a pre-alignment part  22  for pre-aligning the wafer W. For example, an FOUP F, which is a wafer receiving vessel, is mounted on the loading/unloading stage. In addition, the loading/unloading unit  20  may have a needle trace inspection device for performing needle trace inspection on the wafer after the inspection, or the like. 
     The transfer device  30  has a loader (transfer part)  31  for transferring the wafer W to the plurality of inspection devices  11  of the inspection unit  10 , a driving mechanism  32  for moving the loader  31  along a transfer path  50  in the X direction which is an arrangement direction of the inspection devices  11 , and an LM guide  33  for guiding the loader  31  in the X direction. 
     The loader  31  has a transfer base  34  that can move on the LM guide  33  in the X direction, a transfer arm  35  which supports the wafer W and can move in the Y direction, the Z direction (vertical direction), and the θ direction (rotation direction) with respect to the transfer base  34 , an arm driving mechanism (not shown) for driving the transfer arm  35 , and a cover member  36  for covering the wafer W on the transfer arm  35  in a retracting state. A drying gas is introduced into the cover member  36 . The cover member  36  is configured to rotate in the θ direction together with the transfer arm  35 . 
     In the transfer device  30 , while the entire loader  31  is moved in the X direction by the driving mechanism  32 , with the transfer arm  35 , the wafer W before inspection is discharged from the FOUP on the loading/unloading stage and is transferred to the pre-alignment part  22 , the wafer W after the pre-alignment is transferred to a predetermined inspection device  11 , and the wafer W after the inspection is accepted from the predetermined inspection device  11  and is received in the FOUP. The number of the transfer arm  35  may be one, two, or more. The loader  31  is stopped at a transfer position corresponding to each of the plurality of inspection devices  11  and the pre-alignment part  22  so that the transfer operation by the transfer arm  35  is performed at the transfer position. 
     As illustrated in  FIG. 2 , the driving mechanism  32  is of a belt driving type, and includes a timing belt  51  in which the transfer base  34  is installed via a connection member  52 , a pair of gear pulleys  53  (only a driving side is illustrated) around which the timing belt  51  is wound, and a motor  54  for driving the timing belt  51  via one of the gear pulleys  53 . The gear pulley  53  and the motor  54  are fixed to a base  60  of the inspection system  100  via a support member  55 . Tooth jump prevention blocks  57  are installed above and below the gear pulley  53  so as to press the timing belt  51 . 
     The connection member  52  is connected to an upper end side of the timing belt  51 . As illustrated in  FIG. 3 , teeth corresponding to the inner teeth of the timing belt  51  are formed on an upper surface of the connection member  52 . Furthermore, the inner portion of the timing belt  51  is fitted to the upper surface of the connection member  52  and a pressing member  56  is screwed by screws  58  from the upper side of the timing belt  51 , whereby the timing belt  51  and the connection member  52  are secured. 
     Since the inspection unit  10  is configured by arranging about 10 to 15 inspection devices  11  in the X direction, the length of the transfer path  50  becomes a length of about ten meters and the length of the timing belt  51  between the gear pulley  53  and the other gear pulley (not shown) becomes longer. Thus, there is a risk that the upper end side and the lower end side of the timing belt  51  come into contact. However, in the present embodiment, the upper end side of the timing belt  51  and the transfer base  34  or the lower end side of the timing belt  51  are suppressed from coming into contact with each other by connecting the connection member  52  to the upper end side of the timing belt  51 . 
     As illustrated in  FIG. 4 , a sensor part  71  is installed on the transfer base  34  of the loader  31 . Meanwhile, flag parts  72  are installed to correspond to the sensor part  71  at positions of the base  60  corresponding to the plurality of inspection devices  11  and the pre-alignment part  22  (only portions corresponding to some of the inspection devices  11  are illustrated). 
     As illustrated in  FIG. 5 , the sensor part  71  has two position sensors  71   a  and  71   b  installed side by side in the Y direction orthogonal to the X direction at the same position in the X direction, and each of the flag parts  72  has two flags  72   a  and  72   b  installed side by side in the Y direction orthogonal to the X direction at the same position in the X direction so as to correspond to the two position sensors  71   a  and  71   b . The position sensors  71   a  and  71   b  are configured by, for example, optical sensors formed of a light emitting element and a light receiving element, and when the loader  31  is moved in the X direction, the position sensors  71   a  and  71   b  of the sensor part  71  are configured to pass through the flags  72   a  and  72   b  of each of the flag parts  72 . When the position sensors  71   a  and  71   b  pass through the flags  72   a  and  72   b , signals are generated from the position sensors  71   a  and  71   b . Based on the signals, as will be described later, the deviation of the transfer position of the loader  31  due to a lost motion occurring when the timing belt  51  is driven is corrected so that the wafer W can be transferred to the respective inspection devices  11  and the pre-alignment part  22  with high accuracy. The reason why the two position sensors and the two flags are installed is to reliably perform the position detection even if one position sensor fails. In this case, the number of the position sensors is not limited to two, and may be any suitable number of two or more. Also, one position sensor may be used. 
     A power supply cable for feeding power to the arm driving mechanism for driving the transfer arm  35  or the like, and other cables are connected to the loader  31 . As illustrated in  FIG. 6 , these cables are connected to a power source or the like, with the cables received in a cable duct  75 . The cable duct  75  has a multi-joint structure, and is configured to be bendable at an arbitrary position corresponding to the X direction position of the loader  31 . One end of the cable duct  75  is fixed to the transfer base  34  via an installation member  76 , and the other end thereof is fixed to a predetermined position. Since the transfer path  50  of the loader  31  is as long as 10 to 15 m, two roller units  77  are installed on the base  60  at predetermined intervals to support the cable duct  75  so that the upper end side thereof does not come into contact with the base  60  due to “slackness” of the cable duct  75  when the moving stroke of the loader  31  becomes large. The number of roller units  77  is not limited to two, and may be any suitable number of two or more. 
     The controller  40  controls the respective components constituting the inspection system  100 , for example, each inspection device  11 , the transfer device  30  and the like, and as illustrated in  FIG. 7 , it includes a main controller  41 , an input device  42  such as a keyboard, an output device  43  such as a printer, a display device  44 , a storage device  45 , an external interface  46 , and a bus  47  for connecting these components to each other. The main controller  41  has a CPU, an RAM, and an ROM. The storage device  45  is for storing information and is configured to read information stored in a computer-readable storage medium. The storage medium is not particularly limited, and a hard disk, an optical disc, a flash memory, or the like may be used. In the main controller  41 , the CPU executes a program stored in the ROM or the storage device  45  so as to perform the control of the inspection system  100 . The main controller  41  has a plurality of controllers that control the respective components. One of them is a transfer controller  81  that controls the transfer device  30 . 
     The transfer controller  81  has a coordinate system of the X direction which is the transfer direction of the loader  31 , on software, and has position data in the coordinate system of the transfer position corresponding to each of the plurality of inspection devices  11  and the pre-alignment part  22 . As illustrated in  FIG. 8 , it is configured such that a signal of an encoder  82  of the motor  54  of the driving mechanism  32  and the signals of the position sensors  71   a  and  71   b  are sent to the transfer controller  81 . The transfer controller  81  is configured to confirm the position of the loader  31  in the coordinate system based on the signal from the encoder  82 . Furthermore, when the position sensors  71   a  and  71   b  detect the flags  72   a  and  72   b  installed at the positions corresponding to the plurality of inspection devices  11  and the pre-alignment part  22  while moving the loader  31  in the X direction, the transfer controller  81  is configured to receive detection signals and correct the position of the loader  31  in the coordinate system in the transfer controller  81  based on the detection signals. Although the transfer controller  81  is also configured to control the driving mechanism of the transfer arm  35 , details thereof will be omitted. 
     &lt;Operation of the Inspection System&gt; 
     Next, an operation of the inspection system configured as described above will be described with focus on the control of the transfer device. 
     First, the loader  31  of the transfer device  30  is moved in the X direction to the position corresponding to the FOUP mounted on the loading/unloading stage part  21  of the loading/unloading unit  20  to discharge the wafer W before inspection from the FOUP F by the transfer arm  35 . Subsequently, the loader  31  is moved in the X direction to the transfer position with respect to the pre-alignment part  22  to load the wafer W on the transfer arm  35  into the pre-alignment part  22 . After the pre-alignment, the wafer W is discharged from the pre-alignment part  22  by the transfer arm  35 , the loader  31  is moved in the X direction to the transfer position with respect to any one inspection device  11  to load the wafer W on the transfer arm  35  into the inspection device  11 . 
     In the inspection device  11 , the wafer W is loaded on the loading table, and the probe needles of the probe card are brought into contact with the electrodes of the semiconductor device formed on the wafer W so that the electrical inspection is performed by the tester through the test head. 
     After the wafer is inspected, the loader  31  is moved in the X direction to the transfer position for the inspection device  11  to discharge the wafer W after the inspection from the inspection device  11  by the transfer arm  35  and to return the wafer W to the FOUP F on the loading/unloading stage  21 . 
     The processing as described above is continuously performed on a plurality of wafers W. 
     The movement of the loader  31  in the X direction at this time is performed by the driving mechanism  32 . The position control of the loader  31  at this time is performed by the transfer controller  81  of the controller  40 . The transfer controller  81  has coordinates corresponding to the position of the loader  31  and has position data in the coordinate system of the transfer position of the wafer W by the loader  31  with respect to each of the plurality of inspection devices  11  and the pre-alignment part  22 . Then, the position control of the loader  31  in the X direction is performed using the position data. 
     An inspection system having a plurality of inspection devices generally uses a ball screw drive or a linear motor drive as a driving method in the X direction if the number of inspection devices is about 4 or 5, but when about 10 to 15 inspection devices  11  are arranged in the X direction and the length of the transfer path  50  is about 10 meters as in the present embodiment, it is technically difficult to apply the ball screw drive or the linear motor drive. Therefore, in the present embodiment, a belt driving method is adopted as the driving mechanism  32  for driving the loader  31  in the X direction. 
     However, when the loader  31  is transferred over a long distance reaching about 10 meters by the belt driving method, there is an influence of lost motion due to slackness, elongation or the like of the timing belt  51 . Thus, the position in the coordinate system of the transfer controller  81  and the actual position of the loader  31  may deviate from each other. Therefore, the transfer position in the coordinate system of the loader  31  with respect to the inspection device  11  or the pre-alignment part  22  may deviate from the original transfer position, there is a possibility of trouble in the transfer of the wafer W due to a deviation of the transfer arm  35  as illustrated in  FIG. 9 . 
     Therefore, in the present embodiment, the position sensors  71   a  and  71   b  are installed on the transfer base  34  of the loader  31  so that the coordinates of the transfer controller  81  are corrected based on the actual positions detected by the position sensors  71   a  and  71   b.    
     That is, the flags  72   a  and  72   b  are respectively installed at predetermined positions corresponding to the plurality of inspection devices  11  and the pre-alignment part  22 , and each time the position sensors  71   a  and  71   b  pass through the flags  72   a  and  72   b  during the movement of the loader  31  in the X direction, the transfer controller  81  receives a signal indicating it and corrects the position data of the loader  31  in the coordinate system in the transfer controller  81  based on the signal to correct the deviation of the transfer position. 
     The position control by the transfer controller  81  at this time will be specifically described.  FIG. 10  is a flowchart illustrating a flow at that time, and  FIG. 11  is an explanatory view illustrating position correction of the transfer position. 
     First, a search start position and a search end position of the position sensors  71   a  and  71   b  are set (step S 1 ). The search start position and the search end position at this time are set to, for example, positions of 5 mm before and after the flags  72   a  and  72   b , as illustrated in  FIG. 11 . 
     Subsequently, the loader  31  is moved in the X direction, and search is performed by the position sensors  71   a  and  71   b  from the search start position to the search end position (step S 2 ). 
     Then, when the position sensors  71   a  and  71   b  detect the flags  72   a  and  72   b , interruption signals are received and positions thereof are stored as teaching positions (step S 3 ). 
     Next, distances to the transfer position using the teaching positions as a reference are stored as parameters (step S 4 ). 
     At this time, due to the influence of deflection or elongation of the timing belt, a deviation occurs between the loader position in the coordinate system of the transfer controller  81  and the actual loader position, but the deviation is corrected by correcting the position in the coordinate system using the teaching positions based on actual detection signals of the position sensors  71   a  and  71   b  as a reference. That is, as illustrated in  FIG. 11 , the deviation of the designed position which is the position in the coordinate system of the software is corrected by using the detection positions (teaching positions) actually detected by the position sensors  71   a  and  71   b  as a reference (correction amount 1 and correction amount 2). Then, the distances from the teaching positions to the transfer position are stored as the parameters. At this time, the designed transfer position is corrected based on a difference corresponding to the correction value 1 and the correction value 2, and the corrected transfer position is stored and registered (registered transfer position). The parameter corresponding to the position sensor  71   a  is (designed value+correction value 1-difference), and the parameter corresponding to the position sensor  71   b  is (designed value+correction value 2-difference). 
     If the interruption signal of one of the position sensors  71   a  and  71   b  is not detected, the interruption signal of the other position sensor is used and a message of a failure of the position sensor which is not detected is issued. In addition, even when the signal detection positions of both position sensors deviate, a message is issued. 
     In this manner, the loader position in the coordinate system in the transfer controller  81  is corrected based on the positions where the position sensors  71   a  and  71   b  actually detect the flags  72   a  and  72   b . Thus, a transfer error (position deviation) in the X direction can be appropriately corrected to set the transfer position of the loader  31  with high accuracy and to accurately transfer the wafer W as the target object. In addition, since the position in the coordinate system of the transfer controller  81  is corrected each time the position sensors  71   a  and  71   b  detect the flags  72   a  and  72   b  in the transfer position of each of the plurality of inspection devices  11  and the pre-alignment part  22 , the stroke in the X direction is subdivided, whereby, even if a transfer error occurs, the error does not become large. 
     Furthermore, by installing the two position sensors  71   a  and  71   b , even when one position sensor is damaged, it is not necessary to stop the inspection system, which does not lower the device operation rate. 
     In order to more accurately set the transfer position, it is preferable to install a positioning mechanism as illustrated in  FIG. 12 . 
     This positioning mechanism  90  has a V block  91  fixed to an upper surface of the base  60 , a wedge member  92  which has a roller  93  fitted to a V-shaped groove of the V block  91  and being rotatable, at a leading end thereof, and which is installed on the transfer base  34  of the loader  31  so as to be moved up and down, and a driving part  94  for moving the wedge member  92  up and down. The positioning mechanism  90  serves to set the transfer position of the loader  31  with high accuracy, and to mechanically position the loader  31  at an accurate transfer position by fitting the roller  93  of the wedge member  92  to the V-shaped groove of the V block  91 . At this time, the position where the roller  93  is fitted to the V-shaped groove is a position corresponding to a transfer position with physically high accuracy in advance. 
     The operation of the positioning mechanism  90  is, for example, as illustrated in  FIGS. 13A to 13C . In  FIG. 13A , the loader  31  is in a state before reaching the transfer position, and the wedge member  92  is retracted above the V block  91 . The loader  31  is transferred in the X direction, and lowers the wedge member  92  at a timing when the wedge member  92  reaches the V block  91 , as illustrated in  FIG. 13B . The loader  31  is stopped at the registered transfer position described above according to a command from the transfer controller  81 , but there is a possibility that this registered transfer position slightly deviates from the actual transfer position. 
     At this time, even if the loader  31  is stopped at a position slightly deviated from the actual transfer position, as illustrated in  FIG. 13C , the roller  93  is moved along the V-shaped groove so that the loader  31  can be accurately positioned at the actual transfer position. Thus, it is possible to realize highly accurate positioning. 
     Furthermore, in the transfer device  30 , since the belt driving method is adopted as the driving method of the driving mechanism  32  for moving the loader  31  along the transfer path  50  in the X direction, when the length of the transfer path  50  becomes longer by about ten meters as in the present embodiment, the timing belt also becomes longer, and as illustrated in  FIG. 14 , the slackness of the timing belt  51  is increased. Conventionally, the connection member  52  that connects the transfer base  34  to the timing belt  51  is often connected to the lower end side of the timing belt  51 . However, in the case where the transfer stroke is long, if the connection member  52  is connected to the lower end side of the timing belt  51 , as illustrated in  FIG. 15 , when the loader  31  is moved in the X direction, the lower end side of the timing belt  51  is raised up and the upper end side and the lower end side of the timing belt  51  may come into contact with each other. In the present embodiment, since the connection member  52  is connected to the upper end side of the timing belt  51 , the upper end side and the lower end side of the timing belt  51  can be suppressed from coming into contact with each other. Furthermore, due to the deflection of the timing belt  51  by the long stroke, the lower end side of the timing belt  51  may come into contact with the base  60 , but this can be solved by raising the position of the gear pulley  53  to a position in consideration of the deflection of the timing belt  51 . By preventing the timing belt  51  from coming into contact with another place or by preventing the upper end side and the lower end side of the timing belt  51  from coming into contact with each other in this way, it is possible to prevent dust generation and to stably run the loader  31 . In addition, it is possible to suppress an undesirable tension from being applied to the timing belt  51 , and to realize more high accurate position control. 
     Furthermore, when the moving stroke of the loader  31  in the X direction becomes longer as the transfer path  50  of the loader  31  in the X direction is as long as 10 to 15 m, as illustrated in  FIG. 16 , the “amount of sagging” on the upper end side of the cable duct  75  is increased, and for example, if the moving stroke of the loader  31  in the X direction is about 9 m, the cable duct  75  may come into contact with the base  60 . On the other hand, in the present embodiment, since the two roller units  77  for supporting the cable duct  75  are installed on the base  60 , even when the moving stroke of the loader  31  is large, the cable duct  75  can be prevented from coming into contact with the base  60 . Thus, it is possible to prevent dust generation caused by the cable duct  75  coming into contact with the base  60 , and to stably run the loader  31 . 
     OTHER APPLICATIONS 
     Furthermore, the present disclosure is not limited to the aforementioned embodiment but may be differently modified within the scope of the spirit of the present disclosure. For example, in the aforementioned embodiment, there has been described an example in which the position sensors are installed on the loader side, but the position sensors may be installed at each transfer position on the base side. 
     In addition, in the aforementioned embodiment, the optical sensors formed of the light emitting element and the light receiving element are exemplified as the position sensors, but the present disclosure is not limited thereto and other position sensors such as a proximity sensor, a contact type sensor, or the like may be used. 
     Moreover, in the aforementioned embodiment, there has been described a case where the transfer device is applied to the inspection system. However, the present disclosure is not limited to the inspection system and may be applied to various systems as long as the transfer part is moved by a belt driving method using a timing belt. 
     Furthermore, in the aforementioned embodiment, there has been described an example in which the probe device is exemplified as the inspection device, but the inspection device is not limited to the probe device. 
     Moreover, in the aforementioned embodiment, there has been described an example in which the semiconductor wafer is exemplified as the target object, but the target object is not limited to the semiconductor wafer. 
     EXPLANATION OF REFERENCE NUMERALS 
       10 : inspection unit,  20 : loading/unloading unit,  22 : pre-alignment part,  30 : transfer device,  31 : loader,  32 : driving mechanism,  33 : LM guide,  34 : transfer base,  35 : transfer arm,  40 : controller,  41 : main controller,  50 : transfer path,  51 : timing belt,  52 : connection member,  53 : gear pulley,  54 : motor,  55 : support member,  60 : base,  71 : sensor part,  71   a ,  71   b : position sensor,  72 : flag part,  72   a ,  72   b : flag,  75 : cable duct,  77 : roller unit,  81 : transfer controller,  90 : positioning mechanism,  91 : V-block,  92 : wedge member,  93 : roller,  100 : inspection system, W: semiconductor wafer (object to be transferred)