Abstract:
Provided is a substrate transfer apparatus which can perform stable and highly accurate transfer without making a configuration complicated. A substrate transfer apparatus according to the present invention includes a multijoint arm whose one end is arranged on a base and the other end is connected to a hand for supporting a substrate, a linear guide for guiding a rectilinear movement of the hand, and a belt driving mechanism for moving the hand along a guide rail of the linear guide. The substrate transfer apparatus having such a configuration supports a load acting on the hand by the multijoint arm and ensures rectilinear transfer performance of the hand by the linear guide. Therefore, since a special mechanism for passing the substrate through a dead point is not required, the configuration is prevented from becoming complicated. Furthermore, since the load does not directly act on the linear guide, high transfer accuracy can be obtained.

Description:
FIELD 
     The present disclosure relates to a substrate transfer apparatus for transferring a substrate to be processed, such as a semiconductor substrate and a glass substrate. 
     BACKGROUND 
     In recent years, there are known multi-chamber apparatuses in which various substrate treatments can be consistently carried out under vacuum by arranging a plurality of process chambers around a transfer chamber so as to center on the transfer chamber and connecting them via gate valves, as substrate processing apparatuses for processing substrates to be processed, such as semiconductor wafers and glass substrates for liquid crystal display devices under vacuum. The multi-chamber type vacuum processing apparatus of this type is provided with a substrate transfer apparatus for automatically carrying in/out the substrates from the transfer chamber to each of the process chambers. 
     As the substrate transfer apparatus, a parallel link type apparatus as shown in  FIG. 7  is known (see Patent Document 1 below), for example. The parallel link type substrate transfer apparatus  5  shown in the figure includes a pair of rotating shafts  1 ,  2  to at least one of which a driving source is connected, first arms  11 ,  12 , one end of each of which is connected to the rotating shafts  1 ,  2 , a pair of second arms  21 ,  22 , one end of each of which is rotatably connected to the corresponding one of the other ends of the first arms  11 ,  12 , and a hand  4  rotatably coupled to each of the other ends of the second arms  21 ,  22 . 
     The first arms  11 ,  12  and the second arms  21 ,  22  have the same arm length and form a parallel link mechanism. Therefore, by rotating the rotating shafts  1 ,  2  in opposite directions, angles  8  respectively formed by the first arms  11 ,  12  and the second arms  21 ,  22  change, and the hand  4  is moved in upward and downward directions in the figure. Accordingly, it becomes possible to transfer a substrate W on the hand  4  to any position.
     Patent Document 1: Japanese Patent Application Laid-open No. Hei 9-283588   Patent Document 2: Japanese Patent Application Laid-open No. 2004-228370   

     SUMMARY 
     Problems to be Solved by the Invention 
     In the parallel link type substrate transfer apparatus of the past shown in  FIG. 7 , the substrate W needs to pass through a position where the first arms  11 ,  12  and the second arms  21 ,  22  become parallel to each other (θ=0°) when the substrate W is transferred from the front to the back, for example. This position corresponds to the dead point of the parallel link mechanism, and interferes with a smooth transfer of the substrate W. Therefore, the substrate transfer apparatus  5  shown in the figure includes a dead point escaping mechanism which is composed of a first pulley  6  concentrically fixed to the rotating shaft  2 , a second pulley  7  concentrically fixed to a connecting portion between the first arm  11  and the second arm  21 , and a belt  8  spanned between the first pulley  6  and the second pulley  7 . With this configuration, it becomes possible to stably transfer the substrate W by directly transmitting a rotational force of the rotating shaft  2  to the second arm  21  via the belt  8  to smoothly pass the substrate W through the dead point position of the link. 
     However, in the parallel link type substrate transfer apparatus, there is a problem that because the dead point escaping mechanism as described above is required for smoothly passing the substrate through the dead point of the link mechanism, the configuration of the apparatus becomes complicated. Further, there is also a problem that the parallel link type substrate transfer apparatus does not always have high capability of linearly transferring substrates, and thus it is difficult to obtain high feeding accuracy. 
     In contrast, a linear motion type substrate transfer apparatus in which a hand is moved along a linear guide is known (see Patent Document 2 above). There is an advantage that the linear motion type substrate transfer apparatus can make the configuration simple because it has no dead point as in the parallel link type substrate transfer apparatus. Further, the linear motion type substrate transfer apparatus is excellent in capability of linearly transferring substrates, and thus high feeding accuracy can easily be obtained. 
     However, in the linear motion type substrate transfer apparatus, self-weights of the substrate to be transferred and the hand directly act on the linear guide. The linear guide has a problem in that due to low load characteristics, when a high load acts on the linear guide, substrate transfer accuracy deteriorates and high feeding accuracy cannot be obtained, which makes it impossible to cope with an increase in a size of the substrate that is expected to make a further progress in the future. 
     The present invention has been made in view of the above-mentioned problems, and it is therefore an object of the present invention to provide a substrate transfer apparatus which can perform stable and highly accurate transfer without making the configuration complicated. 
     Means for Solving the Problems 
     To solve the above-mentioned problems, according to the present invention, provided is a substrate transfer apparatus including a multijoint arm whose one end is arranged on a base and the other end is connected to a hand for supporting a substrate, a linear guide configured to guide a rectilinear movement of the hand, and a belt driving mechanism configured to move the hand along a guide rail of the linear guide. 
     In the substrate transfer apparatus according to the present invention that has the above mentioned configuration, the multijoint arm does not have its own driving source, and expands and contracts by driving of the belt driving mechanism connected to the hand to linearly move the hand along the guide rail of the linear guide. The substrate transfer apparatus having such a configuration supports a load that acts on the hand by the multijoint arm, and ensures the linear transfer capability of the hand by the linear guide. Therefore, since a special mechanism for passing the substrate through the dead point is not required, the configuration is prevented from becoming complicated. Furthermore, since the load does not directly act on the linear guide, high transfer accuracy and durability can be obtained at the same time. 
     The belt driving mechanism according to the present invention includes a driving pulley connected to a driving shaft, driven pulleys, a belt member spanned between the driving pulley and the driven pulleys, a connecting member that connects the belt member and the hand, and configured to move along the guide rail of the linear guide, and a frame member arranged on the base and supports the driving pulley and the driven pulleys. The belt member converts a rotational motion of the driving pulley into a linear motion of the hand to achieve highly accurate feed control. 
     Further, the driving pulley and the driven pulleys are provided in a couple, and auxiliary pulleys that adjusts a tension of the belt member are respectively provided between the driven pulleys and the driving pulleys. With this configuration, it becomes possible to maintain an appropriate tension of the belt member and surely transmit a rotational driving force of the driving pulley to the belt member. 
     It should be noted that when a sufficient friction force in a joint surface between the driving pulley and the belt member is maintained, the rotational angle of the driving shaft accurately coincides with the travel distance of the hand without a backlash. However, if a displacement from a desired position may be caused by a slippage due to an external force accidentally applied thereto, a plurality of engaging protrusions may be provided on a circumferential surface of the driving pulley and engaging holes that engage with the plurality of engaging protrusions may be formed on a circumferential surface of the belt member, in order to avoid such a case. 
     Further, by making the driving shaft detachable from the driving pulley, it becomes possible to enhance maintainability of the belt driving mechanism. With this structure, a remarkable effect can be obtained especially in the case where the present invention is applied to substrate transfer within a vacuum chamber. 
     It should be noted that the configuration of the multijoint arm is not specifically limited. For example, a configuration in which the multijoint arm includes a pair of first arms, one end of each of which is rotatably supported by the base, and a pair of second arms, one end of each of which is rotatably coupled to a corresponding one of the other ends of the pair of first arms, and the hand is rotatably coupled to each of the other ends of the pair of second arms can be employed. The length of each of the first arms and second arms may be the same or may be different. 
     Effect of the Invention 
     As described above, according to the substrate transfer apparatus of the present invention, high transfer accuracy of the substrate can be obtained without making the configuration complicated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view schematically illustrating a configuration of a substrate transfer apparatus according to an embodiment of the present invention. 
         FIG. 2  is an overall perspective view of a belt driving mechanism constituting a substrate transfer apparatus according to the embodiment of the present invention. 
         FIG. 3  is a plan view of the belt driving mechanism shown in  FIG. 2 . 
         FIG. 4  is a perspective view of the belt driving mechanism shown in  FIG. 2  in the vicinity of a driving pulley. 
         FIG. 5  is a perspective view of the belt driving mechanism shown in  FIG. 2  at a position immediately below a hand. 
         FIG. 6  is a perspective view showing a relationship between the belt driving mechanism shown in  FIG. 2  and a driving shaft. 
         FIG. 7  is a plan view showing a configuration of a substrate transfer apparatus of the related art. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A substrate transfer apparatus of this embodiment is arranged in a vacuum transfer chamber of a multi chamber apparatus (not shown) having a plurality of vacuum processing chambers disposed around the vacuum transfer chamber, and configured to automatically transfer a substrate to be processed, such as a semiconductor wafer and a glass substrate, among the plurality of vacuum processing chambers including load/unload chambers. 
       FIG. 1  is a perspective view showing the configuration of a substrate transfer robot  30  according to an embodiment of the present invention. This substrate transfer robot  30  includes a multijoint arm  31  whose tip portion is coupled to a hand  32 , and a belt driving mechanism  38  for linearly moving the hand  32 . It should be noted that the configuration of the belt driving mechanism  38  is shown in a simplified way for easier comprehension. 
     In this embodiment, the multijoint arm  31  is configured in a parallel link form, which has a pair of first arms  41 ,  41 , one end of each of which is rotatably supported by a base  33 , and a pair of second arms  42 , 42 , one end of each of which is rotatably coupled to a corresponding one of the other ends of the pair of first arms  41 ,  41 . The first arm  41  and the second arm  42  have the same arm length, but the length is not limited thereto and may be differed. The hand  32  is composed of a block portion  34  rotatably connected to each of the other ends of the pair of second arms  42 ,  42 , and a plurality of fork portions  35  for supporting a substrate. 
     The base  33 , on which the one end of the multijoint arm  31  configured as described above is arranged, is provided with the belt driving mechanism  38  for controlling the travel distance and travel direction of the hand  32 , and a linear guide  36  for guiding a linear motion of the hand  32 . The belt driving mechanism  38  linearly moves the hand  32  along a guide rail  37   a  of the linear guide  36 . Hereinafter, a description of details of the belt driving mechanism  38  will be made with reference to  FIGS. 2 to 5 . 
       FIGS. 2 and 3  are a perspective view and a plan view showing a specific configuration example of the belt driving mechanism  38 , respectively. The belt driving mechanism  38  includes a driving pulley  43  coupled to a driving shaft  55  ( FIG. 6 ), driven pulleys  44   a ,  44   b , and a belt member  46  spanned between the driving pulley  43  and the driven pulleys  44   a ,  44   b . The driven pulleys  44   a ,  44   b  are provided in a pair, and the distance between them is appropriately set in accordance with the travel distance of the hand  32 . 
     Auxiliary pulleys  45   a ,  45   b  for adjusting a tension of the belt member  46  are provided between each of the driven pulleys  44   a ,  44   b  and the driving pulley  43 , thus enhancing an attachment force between the driving pulley  43  and the belt member  46 . 
     The belt driving mechanism  38  converts a rotational motion of the driving pulley  43  to a straight running motion of the belt member  46 . In particular, as shown in  FIG. 4 , it is preferable that a plurality of engaging protrusions  43   a  are formed on a circumferential surface of the driving pulley  43 , and engaging holes  46   a  that engage with the engaging protrusions  43   a  are provided on a belt surface of the belt member  46 . Thus, a slippage between the driving pulley  43  and the belt member  46  can be prevented, and the rotational force of the driving pulley  43  can surely be transmitted to the belt member  46 . It should be noted that an illustration of a frame member  47  is omitted in  FIG. 4 . 
     Axial center portions of the driven pulleys  44   a ,  44   b  and the auxiliary pulleys  45   a ,  45   b  are collinearly aligned. The belt member  46  is composed of a metal belt formed of stainless steel and the like and is spanned between the pulleys within a horizontal plane being a substrate transfer surface. Thus, the configuration of the belt driving mechanism  38  is reduced in size. Further, the belt driving mechanism  38  can easily be provided in a vacuum transfer chamber. 
     The driving pulley  43 , the driven pulleys  44   a ,  44   b , and the auxiliary pulleys  45   a ,  45   b  are rotatably supported by the frame member  47 . The frame member  47  includes bracket portions  48   a ,  48   b  for supporting the driven pulleys  44   a ,  44   b , bracket portions  49   a ,  49   b  for supporting the auxiliary pulleys  45   a ,  45   b , and a base portion  50  for supporting the driving pulley  43 . It should be noted that each of the bracket portions  48   a ,  48   b ,  49   a ,  49   b  is provided with an adjusting mechanism portion S for adjusting the shaft supporting positions of the driven pulleys  44   a ,  44   b  and auxiliary pulleys  45   a ,  45   b.    
     The guide rail  37   a  of the linear guide  36  is positioned on an inverse-L-shaped linear angled portion  47   a  of the frame member  47 . The guide rail  37   a  is arranged parallel to the belt surface of the belt member  46 , which linearly extends from one driven pulley  44   a  to the other driven reel  44   b . It should be noted that the guide rail  37   a  may of course be configured by combining a plurality of rails. 
     On the other hand, a slider  37   b  of the linear guide  36  that fits with the guide rail  37   a  is connected to the hand  32  and the belt member  46  via the connecting member  51  as shown in  FIG. 5 . Here,  FIG. 5  is a perspective view showing the configuration of the belt driving mechanism  38  at a position immediately below the hand  32 , and an illustration of the frame member  47  is omitted for easier comprehension. 
     A lower end portion  51   a  of the connecting member  51  is integrally fixed to the belt member  46 , and an upper end portion  51   b  is fixed to the block portion  34  of the hand  32  via a load buffering mechanism  52  to be described later. An arm portion  51   c  connected to the slider  37   b  of the linear guide  36  is formed at substantially the center portion of the connecting member  51  so as to protrude therefrom. With the above-described configuration, when the belt member  46  travels, the hand  32  is linearly moved along the guide rail  37   a  of the linear guide  36  via the connecting member  51 . 
     The load buffering mechanism  52  is provided for the purpose of preventing a load in the vertical direction that acts on the hand  32  from acting directly on the linear guide  36 . In the substrate transfer apparatus  30  of this embodiment, a load in the vertical direction that acts on the hand  32  is supported by the arms  41 ,  42  of the multijoint arm  31 , so the load does not directly act on the linear guide  36 . However, because a deflection may be caused in the multijoint arm  31 , for example, the above-described load buffering mechanism  52  is provided between the hand  32  and the connecting member  51  in this embodiment to prevent the load from directly acting on the guide rail  36 . The load buffering mechanism  52  can be composed of, for example, a block body incorporating an impact absorber  52   a  such as an elastic material including rubber and a spring pin. 
     The belt driving mechanism  38  configured as described above is arranged on the base  33  via a cylindrical fix portion  53  coaxially positioned immediately below the driving pulley  43  and integrally fixed to the base portion  50 . The base  33  for supporting the multijoint arm  31  and the belt driving mechanism  38  is arranged on a rotating table  40  mounted to a rotating mechanism portion  39  ( FIG. 1 ). The rotating mechanism portion  38  rotatably supports the base  33  with respect to a bottom wall surface of the vacuum transfer chamber (not shown). The driving pulley  43  of the belt driving mechanism  38  is aligned at a rotational axial center potion of the base  33 . 
     The driving shaft  55  for rotating the driving pulley  43  is configured to be detachable from the driving pulley  43 , as shown in  FIG. 6 . The driving shaft  55  includes a rotating vacuum sealing mechanism  57  and is inserted from an atmospheric side and coupled to an axial center portion of the driving pulley  43  via the bottom wall of the vacuum transfer chamber (not shown). On an outer circumferential side of the driving shaft  55 , a pivot shaft  56  for turning the base  33  is arranged concentrically with the driving shaft  55 . The pivot shaft  55  is integrally coupled to the frame member  47  (fix portion  53 ) of the belt driving mechanism  38 , and gives the frame  47  a rotational axial force to obtain a pivot action of the base  33 . 
     In the substrate transfer apparatus  30  of this embodiment configured as described above, the driving pulley  43  is rotated by rotational driving of the driving shaft  55  so that the belt member  46  is moved. The hand  32  is linearly moved along the guide rail  37   a  of the linear guide  36  by traveling of the belt member  46 , since the hand  32  is connected to the belt member  46  via the connecting member  51 , and the connecting member  51  is fixed to the slider  37   b  of the linear guide  36 . Thus, the travel distance of the hand  32  is controlled by the rotating amount of the driving pulley  43 , and the travel direction of the hand  32  is controlled by the rotating direction of the driving pulley  43 . 
     At this time, each of the arms  41 ,  42  of the multijoint arm  31  does not have its own driving source, and expands and contracts in accordance with the running direction and running distance of the belt member  46 . Therefore, the expand and contract action of the multijoint arm  31  can be carried out smoothly even at a dead point position of the parallel link mechanism where an angle formed by the first arm  41  and the second arm  42  becomes 0°. Thus, stable straight transfer capability of the hand  32  can be obtained. 
     Further, in the substrate transfer apparatus  30  of this embodiment, since the load in the vertical direction acting on the hand  32  is supported by the multijoint arm  31 , the load is prevented from directly acting on the linear guide  36 , whereby degradation in travel accuracy of the hand  32  by the linear guide  36  can be prevented. Accordingly, high feed accuracy or transfer accuracy and durability of the hand  32  can be obtained at the same time. 
     Further, in the substrate transfer apparatus  30  of this embodiment, because each pulley and the belt member configuring the belt driving mechanism  38  are modularized on the frame member  47 , and the driving shaft  55  of the belt driving mechanism  38  is configured to be detachable from the driving pulley  43 , it is possible to facilitate removing of the belt driving mechanism  38  and improve maintainability. In addition, since the pivot shaft  56  of the base  33  is arranged concentrically with the driving shaft  55 , the configuration of the driving source of the substrate transfer apparatus  30  can be reduced in size and simplified. 
     The embodiment of the present invention has been described above, but the present invention is of course not limited thereto and various modifications can be made based on the technical idea of the present invention. 
     For example, in the embodiment described above, the belt member  46  configuring the belt driving mechanism  38  is made of metal, but the material is not limited thereto and other materials such as a resin can also be used. 
     In addition, in order to enhance an attachment force between the driving pulley  43  and the belt member  46 , the driving pulley  43  may be made of a permanent magnet, and the belt member  46  may be made of a ferromagnetic material. Alternatively, a pinching force of the belt member  46  may be enhanced by magnetically coupling the driving pulley  43  and the auxiliary pulleys  45   a ,  45   b.    
     Further, the multijoint arm  31  is not limited to the parallel link type described above. In addition, the substrate transfer system can be applied not only to substrate transfer within a vacuum atmosphere, but also to substrate transfer in an air atmosphere.