Abstract:
The present invention generally provides a processing system having a robot assembly which includes a multiple sided robot blade that can support a substrate on at least two sides thereof and associated methods to transfer one or more substrates in a processing system. An unprocessed substrate can be supported on the blade while a processed substrate is retrieved from a location to which the unprocessed substrate is to be delivered. The processing throughput rate is increased by reducing the movements required by the robot to exchange processed substrates and unprocessed substrates, thus decreasing the swap time.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a divisional of co-pending U.S. patent application Ser. No. 09/398,317, filed Sep. 16, 1999, which is herein incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an apparatus and method for transferring objects in a processing system. More specifically, the present invention relates to a robot assembly having a multiple sided robot blade which can support one or more substrates.  
           [0004]    2. Background of the Related Art  
           [0005]    Modern semiconductor processing systems typically process a large number of substrates by moving the substrates between a series of process chambers or enclosures using a robot. To increase the throughput rates of substrates, the trend is to increase the speeds at which substrates are moved in the system. However, increased speeds add complexity to the substrate handling systems. Increased speeds have decreased the allowable tolerances necessary to maintain repeatability because precise movement is needed to avoid damaging the substrate or the films formed thereon as the substrate is moved between the process chambers or enclosures using the robot.  
           [0006]    One type of system used in substrate processing is a chemical mechanical polishing (CMP) system used to polish a substrate surface to remove high topography, surface defects, scratches, or embedded particles. FIG. 1 is a schematic perspective view of one CMP system known as a Mirra® CMP system available from Applied Materials, Inc. of Santa Clara, Calif., which is shown and described in U.S. Pat. No. 5,738,574, incorporated herein by reference. The system  2  includes a loading station  4  and three polishing stations  6  having polishing and/or rinsing pads  8  disposed therein. A rotatable multi-head carousel  10  having four polishing heads  12  is mounted above the stations and indexes the heads from station to station. The loading station  4  is supplied by a front-end substrate transfer region  14  disposed adjacent to the CMP system and is considered a part of the CMP system, although the transfer region  14  may be a separate component. The loading station  4  includes a pedestal  16  on which a substrate is supported following delivery by an overhead track robot  18  prior to and after processing in the polishing stations  6 . Vertically aligned substrate(s)  20  are held in cassette(s)  22  disposed in a fluid in a load tank  24 .  
           [0007]    Generally, an overhead track robot  18  includes a downwardly extending blade support arm  28 , also known as a shoulder. A blade  26  is attached to the blade support arm at a pivot joint  30 , typically referred to as a wrist. The track robot  18  is capable of operating the blade support arm in three directions: in a linear direction along an X-axis across the front of the system, in a vertical direction along a Z-axis, and in a rotational direction about the Z-axis. Additionally, the blade  26  is capable of rotating about pivot joint  30  between a substantially horizontal position and a substantially vertical position. The blade  26  typically includes a vacuum port (not shown) for holding a substrate  20  to the blade during transfer within the system  2 .  
           [0008]    [0008]FIG. 2 is a cross sectional schematic view of the overhead track robot  18 , showing details of the robot components. A blade support arm  28  is vertically disposed below a carriage  32 . The carriage  32  is attached to a drive belt  34  which is supported between two sheaves  36 ,  38 . A motor  40  having a worm gear  42  is mounted on the carriage  32  and engages a mating gear  44  mounted on the support arm  28 . The blade support arm  28  supports a support column  60  that is connected to the pivot joint  30 . The pivot joint  30  includes a first portion  46  connected to the blade support arm  28 , a second portion  48  connected to a blade  26 , and a pivot element  50  pivotally connecting the first portion  46  with the second portion  48  of the pivot joint  30 . The pivot joint  30  allows the blade  26  to rotate at a pivot axis  52  between a horizontal and a vertical position. The blade  26  is a single-sided blade, i.e., the blade has one substrate supporting surface that is used to support the substrate during retrieval and delivery of a substrate  20  from and to the various stations. The carriage  32  houses a motor  54  having a worm gear  56  which passes through a worm nut  58  attached to the support column  60 . The blade support arm  28  houses a motor  62  which is attached to a drive shaft  64  and a worm gear  66 . The worm gear  66  engages a mating gear  68  on the pivot joint  30 . The blade  26  is attached by screws (not shown) to the pivot joint  30 .  
           [0009]    The blade support arm  28  rotates about the Z-axis  70  when the motor  40  rotates the worm gear  42  which in turn rotates the mating gear  44  connected to the blade support arm. In the typical system, the pivot axis  52  is offset from the Z-axis  70  to enable use of a shorter blade  26  and consequently reduce blade deflection when extended horizontally in the system  2  on delivery and retrieval of a substrate  20 . The worm nut  58  rises and lowers on the worm gear  56  as the motor  54  rotates the worm gear  56 , thus raising and lowering the support column  60  attached thereto. To rotate the pivot joint  30  about the pivot axis  52 , the motor  62  rotates the drive shaft  64  which causes the worm gear  66  to rotate. Rotation of the worm gear  66  causes the mating gear  68  to rotate, thus rotating the second portion  48  of the pivot joint  30  and the blade  26  attached thereto.  
           [0010]    Typically, in loading the substrate  20  into the system  2 , the robot  18  rotates the blade  26  into a vertical position, aligns the blade  26  with the substrate, lowers the blade  26  into an adjacent position with the substrate  20 , and vacuum chucks a substrate  20  on a substrate supporting surface of the blade  26 . A vacuum provided to a port on the blade supplies a vacuum to hold the substrate  20  to the supporting surface of the blade  26  so that when the blade is raised vertically, the substrate remains supported by the blade in the vertical position. The robot  18  then rotates the blade  26  about the pivot joint  30  into a substantially horizontal position, moves in the X-direction toward the loading station  4  rotates the blade about the Z-axis  70 , aligns the blade with a loading station  4 , and delivers the substrate to the loading station. The loading station pedestal  16  raises to engage the substrate  20  and lowers the substrate below the blade  26  so that the blade  26  can retract out of the loading station  4 . One of the heads  12  indexes above the pedestal  16 , the pedestal  16  raises the substrate  20  into contact with the head, the head chucks the substrate and indexes to a polishing station  6  for processing. After processing at the station(s), the substrate  20  is returned to the loading station  4 . The robot  18  aligns the robot blade  26  with the loading station  4  to retrieve the processed substrate, retrieves the processed substrate, traverses the X-axis back into an unloading position at the load tank  24 , and returns the substrate  20  to the load tank  24 . The robot then loads another unprocessed substrate and delivers the substrate to the loading station  4 .  
           [0011]    One problem with this conventional design and process is that the system may sit idle while awaiting retrieval of an unprocessed substrate following removal of a processed substrate. The time required for the robot to cycle between a processed substrate and an unprocessed substrate is typically referred to as the “swap” time. In the system referenced in FIG. 1, the swap time includes the time required to retrieve and place a processed substrate in the load tank and retrieve and deliver an unprocessed substrate to the loading station.  
           [0012]    There remains a need for a system and method that can reduce the swap time required to pick up a processed substrate and position an unprocessed substrate for processing in the system.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention generally provides a processing system having a robot assembly which includes a multiple sided robot blade that can support a substrate on at least two sides thereof and associated methods to transfer one or more substrates in a processing system. An unprocessed substrate can be supported on the blade while a processed substrate is retrieved from a location to which the unprocessed substrate is to be delivered. The processing throughput rate is increased by reducing the movements required by the robot to exchange processed substrates and unprocessed substrates, thus decreasing the swap time.  
           [0014]    In one aspect, the invention provides a substrate processing system, comprising an enclosure, a robot as least partially disposed within the enclosure, and a multiple sided robot blade attached to the robot and adapted to support substrates on at least two surfaces thereof. The robot can include a blade support arm connected to a drive mechanism, a pivot joint connected to the blade support arm, a two sided blade connected to the pivot joint, and associated actuators and controllers. In another aspect, the invention provides a robot blade for a substrate processing system, comprising a first and a second substrate supporting surface on opposed faces of the blade.  
           [0015]    In another aspect, the invention provides a method for transferring substrates in a processing system, comprising supporting a first substrate on a first substrate supporting surface of a robot blade, retrieving a second substrate on a second substrate supporting surface of the robot blade from the system, and delivering the first substrate supported on the first substrate supporting surface to the system while supporting the second substrate on the second substrate supporting surface. In another aspect, the invention provides a method of transferring substrates in a processing system using a robot, comprising retrieving a first substrate from a first location and supporting the first substrate on a first substrate supporting surface of a robot blade, positioning the robot blade to retrieve a second substrate from a second location, retrieving the second substrate from the second location and supporting the second substrate on a second substrate supporting surface of the blade, delivering the first substrate to the second location, and delivering the second substrate to another location in the system. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.  
         [0017]    It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0018]    [0018]FIG. 1 is a schematic perspective view of a typical processing system.  
         [0019]    [0019]FIG. 2 is a schematic cross sectional view of a typical track robot having a blade support arm and a robot blade.  
         [0020]    [0020]FIG. 3 is a schematic cross sectional view of one embodiment of the robot of the present invention.  
         [0021]    [0021]FIG. 4 a  is a schematic top view of one embodiment of the robot blade.  
         [0022]    [0022]FIG. 4 b  is a schematic bottom view of the robot blade of FIG. 4 a.    
         [0023]    [0023]FIG. 4 c  is a schematic cross sectional view of FIG. 4 a  through the blade showing the longitudinal channels.  
         [0024]    [0024]FIG. 4 d  is a schematic cross sectional view of FIG. 4 a  through the blade showing the transverse channels.  
         [0025]    [0025]FIG. 4 e  is a schematic side view of the robot blade of FIG. 4 a.    
         [0026]    [0026]FIG. 5 is a schematic cross sectional view of another embodiment of the robot of the present invention.  
         [0027]    [0027]FIG. 6 is a schematic side view of the robot with the blade in a vertical position with a first substrate over a first location.  
         [0028]    [0028]FIG. 7 is a schematic side view of the robot with the blade rotated to a substantially horizontal position with a first substrate.  
         [0029]    [0029]FIG. 8 is a schematic side view of the robot with the blade supporting the first and second substrates on the first and second substrate supporting surfaces, respectively.  
         [0030]    [0030]FIG. 9 is a schematic side view of the robot with the blade rotated about a pivot joint from the position referenced in FIG. 8.  
         [0031]    [0031]FIG. 10 is a schematic side view of the robot with the blade rotated about a first axis.  
         [0032]    [0032]FIG. 11 is a schematic side view of the robot with the blade having unloaded the first substrate into a second location while supporting the second substrate.  
         [0033]    [0033]FIG. 12 is a schematic side view of the robot with the blade in a vertical position with a second substrate over the first location. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0034]    The present invention generally provides a processing system having a robot assembly with a multiple sided robot blade that can support a plurality of substrates on at least two sides thereof. In general, the system includes an enclosure, such as a CMP system  2 , and a robot, such as an overhead track robot  72  shown in FIG. 3. The system may also include a loading station  4  adjacent a plurality of polishing stations  6 . The loading station  4  is supplied with substrates by an overhead track robot  72  disposed in a substrate transfer region  14  above a load tank  24  having a plurality of cassette(s)  22 .  
         [0035]    [0035]FIG. 3 is a schematic cross sectional view of one embodiment of the robot  72  of the system. A carriage  74  is attached to the drive belt  76  which is supported between two sheaves  78 ,  80 . A blade support arm  82  is connected to the carriage  74  and is vertically disposed below the carriage  74 . The blade support arm  82  supports a support column  84  that is connected to a pivot joint  86 . The pivot joint  86  includes a first portion  88  connected to the blade support arm  82 , a second portion  90  connected to a multiple-sided robot blade  94 , and a pivot element  92  pivotally connecting the first portion  88  with the second portion  90  of the pivot joint  86 . The robot blade  94  includes at least two substrate supporting surfaces  96 ,  98  to support one or more substrates. Preferably, the blade support arm  82  can rotate at least 180° around a first axis  100  to assist the blade in moving from a first location to a second location. The pivot joint  86  having a pivot axis  102  allows the blade  94  to rotate at least 180° from a first horizontal position  104  as shown through a vertical position  106  to at least a second horizontal position  108 . The carriage  74  houses a motor  110  having a worm drive  112  which passes through a worm nut  114  attached to the support column  84 . The carriage  74  is connected to a motor  116  having a worm gear  118 . The worm gear  118  is engaged with a mating gear  120  that is connected to the blade support arm  82 . The blade support arm  82  houses a motor  122  which is attached to a drive shaft  124  and a worm gear  126 . The worm gear  126  engages a mating gear  128  coupled to the second portion  90  of the pivot joint  86 .  
         [0036]    The blade support arm  82  rotates about a first axis  100  when the motor  116  rotates the worm gear  118  which in turn rotates the mating gear  120  connected to the blade support arm  82 . The motor  110  rotates the worm gear  112  to raise and lower the support column  84 . The worm nut  114  rises and lowers on the worm gear  112 , thus raising and lowering the support column  84  attached thereto. To rotate the pivot joint  86  about the pivot axis  102 , the motor  122  rotates the drive shaft  124  which rotates the worm gear  126 . The worm gear  126  rotates the mating gear  128  that is coupled to the second portion  90  of the pivot joint  86  and the blade  94  connected thereto.  
         [0037]    In the embodiment shown in FIG. 3, the vertical first axis  100  is substantially aligned in a transverse direction with the horizontal pivot axis  102 , so that the first axis substantially intersects the pivot axis. The intersection of axes allows the first substrate supporting surface  96  to be symmetrically aligned with the second substrate supporting surface  98  when the blade  94  is rotated about the first axis  100  and about the pivot axis  102 . For example, in the embodiment described in FIG. 3, the first substrate supporting surface  96  is disposed upwardly and the second substrate supporting surface  98  is disposed downwardly at position  104 . The blade  94  can be rotated at least 180° about the pivot axis  102  through a vertical position  106  to a second horizontal position  108 , where the first substrate supporting surface  96  is downwardly disposed and the second substrate supporting surface  98  is upwardly disposed. The blade  94  can also be rotated at least 180° about the first axis  100 , so that the blade  94  returns to position  104 , but this time the first substrate supporting surface  96  is downwardly disposed and the second substrate supporting surface  98  is upwardly disposed, in contrast to the original relative positions. Thus, the blade  94  can rotate about both axes  100 ,  102  and preserve the symmetry between substrate positions of the first and the second substrate supporting surfaces  96 ,  98 . The substantial intersection of the two axes  100 ,  102  should be at least enough so that upon repositioning a second substrate to the position of a first substrate, enough symmetry is maintained to satisfy normal manufacturing and placement tolerances of the equipment for interchangeable placement of the substrates. In some embodiments, where the axes are not aligned, the robot  72  could compensate for the relative difference by, for instance, programming a controller  130  for positional relative movements.  
         [0038]    The blade  94  will now be described in reference to FIGS. 4 a  and  4   b . FIG. 4 a  is a schematic top view of the blade  94 . FIG. 4 b  is a schematic bottom view of the blade  94 , showing similar components as the top view of the blade. The blade  94  is an elongated thin member, preferably made of stainless steel, having a first substrate supporting surface  96  and a second substrate supporting surface  98 . The blade  94  can be made of other materials, such as alumina, silicon carbide, or other ceramics or combinations thereof. The blade  94  can have an intermediate section  132  between two end sections  134 ,  136  that is narrower in width than the two end sections. The blade  94  is attached to the pivot joint  86  by screws (not shown) disposed through holes  138 . The first substrate supporting surface  96  defines a longitudinal channel  140  aligned along the length of the blade  94  and a transverse channel  142 , where the longitudinal channel  140  intersects the transverse channel  142 . Similarly, the second substrate supporting surface  98  defines a longitudinal channel  144  and a transverse channel  146 , where the longitudinal channel  144  intersects the transverse channel  146 . The longitudinal channel  140  and transverse channel  142  on the first substrate supporting surface  96  are isolated from the longitudinal channel  144  and transverse channel  146  on the second substrate supporting surface  98 . The channels  140 ,  142 ,  144 ,  146  can be any shape and size as needed to support the particular substrate in the particular process. Each longitudinal channel  140 ,  144  is sealably covered by covers  148 ,  150  respectively, to allow the longitudinal channels to sealably communicate with the transverse channels. Gaskets  152 ,  154  are affixed to the blade  94  in proximity to the transverse channels  142 ,  146  to assist is sealing between the substrate and the respective substrate supporting surface when the substrate is supported by the substrate supporting surface through, for example, a vacuum applied to the channels.  
         [0039]    The second portion  90  of the pivot joint  86  preferably has at least two independent ports  156 ,  158  that are connected to one end of hoses  160 ,  162 , respectively. The port  156  is coupled to a port  164  on the blade  94  which fluidicly communicates with the channel  140 . Similarly, port  158  is coupled to port  166  on the blade  94  which fluidicly communicates with the channel  144 . Another end of the hose  160  is directed past the pivot joint  86  and then upward along the blade support arm  82  to pressure sensor  168  and to valve  170 . Similarly, another end of the hose  162  is directed past the pivot joint  86  and then upward along the blade support arm  82  to pressure sensor  172  and to valve  174 . The valves  170 ,  174  can be mounted on the robot  72  and controlled by controller  130 . The valves  170 ,  174  are preferably three-way valves having three ports. On valve  170 , a first port  176  is connected to a pressure source  178 , the second port  180  is connected to a vacuum source  182 , and the third port  184  is fluidicly connected to the sensor  168  and the hose  160 . Similarly, on valve  174 , a first port  186  is connected to the pressure source  178 , the second port  188  is connected to the vacuum source  182 , and the third port  190  is fluidicly connected to the sensor  172  and the hose  162 .  
         [0040]    The ports  164 ,  166  allow the independent placement of at least two substrates. In other embodiments, a single port, or multiple ports coupled together, could be used so that when one substrate was released on one side, the other substrate on the other side would be released from the vacuum. For instance, in an upright position, a substrate on top of the blade  94  could rely on gravity to remain substantially stationary while a substrate underneath the blade was unloaded, such as a loading station, and then reapply the vacuum to the blade  94  to support the substrate remaining on the blade.  
         [0041]    [0041]FIG. 4 c  is a schematic cross sectional view through the blade, showing the longitudinal channels referenced in FIG. 4 a . Substrate supporting surface  96  includes the longitudinal channel  140  aligned longitudinally to the length of the blade. The longitudinal channel is preferably pneumatically sealed with a cover  148 . The cover  148  can be attached to the blade  94  preferably by welding, such as electron beam welding, or it can be fastened, adhesively attached or otherwise connected. Substrate supporting surface  98  is similarly arranged and the longitudinal channel  144  is preferably pneumatically sealed with a cover  150 . The port  164  is disposed through the cover  148  and fluidicly connected to the channel  140 . Likewise, port  166  is disposed through the blade  94  and fluidicly connected to the channel  144 .  
         [0042]    The cross sectional area of the channels  140 ,  144  is preferably about the same as the cross sectional area of the hoses  160 ,  162 . Furthermore, the channels  140 ,  144  preferably have a width (W) to height (H) ratio of less than about 38:1 and more preferably a W:H ratio of about 21:1 or less.  
         [0043]    [0043]FIG. 4 d  is a schematic cross sectional view through the blade, showing the transverse channels  142 ,  146  referenced in FIG. 4 a . On the substrate supporting surface  96 , the longitudinal channel  140  is fluidicly connected to the transverse channel  142 . On substrate supporting surface  98 , the longitudinal channel  144  is fluidicly connected to the transverse channel  146 . A blade web  192  isolates the longitudinal channel  140  and transverse channel  142  from the longitudinal channel  144  and transverse channel  146 . The isolation of the channels allows independent control over each substrate (not shown) held to each substrate supporting surface  96 ,  98 .  
         [0044]    [0044]FIG. 4 e  is a side view of the blade  94  attached to the pivot joint  86 . Hose  160  is coupled to port  156  and hose  162  is coupled to port  158 . The port  156  is coupled to port  164  on the blade  94  and the port  158  is coupled to the port  166  on the blade  94 , where each of the ports are upwardly disposed on the blade  94 . Gaskets  152 ,  154  are disposed toward the end of the blade  94 .  
         [0045]    Other methods of supporting substrates on the blade can be used, such as electrostatic chucks, adhesive substances such as polymers, and mechanical devices such as “grippers” and other clamps. Also, multiple ports or other methods of support could be used on one substrate supporting surface. For instance, if more than one substrate were supported on one substrate supporting surface, then each substrate could be supported and released independently on that substrate supporting surface.  
         [0046]    A controller  130 , shown in FIGS. 3 and 4 a , controls the functions of the robot movement, rotation and linear actuators, power supplies, and other associated components and functions. In general, the controller  130  preferably comprises a programmable microprocessor and executes system control software stored in a memory, which in the preferred embodiment is a hard disk drive, and can include analog and digital input/output boards, interface boards, and stepper motor controller boards (not shown). The controller  130  controls electrical power to the components of the system and includes a panel that allows an operator to monitor and operate the system. Optical and/or magnetic sensors (not shown) are generally used to move and determine the position of movable mechanical assemblies. The controller  130  also controls a pressure and a vacuum system, such as pressure source  178 , vacuum source  182 , and valves  170 ,  174 . A vacuum can be supplied through the hoses  160 ,  162  to the blade  94  when the blade is lowered into the load tank  24  and allows the blade to retrieve and support the substrate  20 . The particular sensor, either sensor  168  or sensor  172 , coupled to the surface of the blade supporting the substrate  20  senses a change in vacuum performance with the substrate on the particular surface. The surface of the blade  94  not supporting a substrate  20  is exposed to the fluid in the load tank  24  and can entrain some fluid into the channel from that surface. The sensor for the respective surface with the entrained load tank fluid senses no8 substrate on that surface and switches the respective valve from the valve second port which allows vacuum to the respective port on the blade to the valve first port which allows pressurized fluid to the respective port on the blade. The pressurized fluid flows outward through the channel on the substrate supporting surface not supporting the substrate to purge the channel of the load tank fluid, thus creating a purge mode, while the port to the substrate supporting surface supporting the substrate maintains vacuum on the substrate. Preferably, the controller  130  defaults to a purge mode except when the particular surface(s) is supporting the substrate(s).  
         [0047]    [0047]FIG. 5 is a schematic perspective view of another embodiment of the robot including the multiple sided blade  94  and associated components. In this embodiment, the robot blade is able to rotate about a blade axis  194  in addition to being able to rotate about the first axis  100  and the pivot axis  102 , described herein. The pivot joint  196  includes a first portion  198  connected to the blade support arm  82 , a second portion  200  connected to a rotatable actuator  202 , and a pivot element  204  pivotally connecting the first portion  198  with the second portion  200  of the pivot joint  196 . The rotatable actuator  202  is coupled to the blade  94  and can rotate the blade about the blade axis  194 . The actuator  202 , such as a servomotor, preferably directly drives the rotation of the blade  94 . The actuator  202  could have the typical pneumatic lines if pneumatic actuation is used. The controller  130 , referenced in FIG. 3, can also be used to control the actuator. A sensor  206 , such as an optical sensor, may be coupled to the actuator  202  to determine the position of the blade  94  and provide input to the controller  130 . The pivot joint  196  allows the blade  94  to rotate at the pivot axis  102 . The blade support arm  82  can also rotate about 180° around the first axis  100 .  
         [0048]    The actuator  202  can rotate the blade  94  about the blade axis  194  to selectively position the first substrate supporting surface  96  and the second substrate supporting surface  98  in a face up or face down position. In the embodiment shown, the pivot joint  196  could be rotated about 90° from a substantially vertical position to a substantially horizontal position to retrieve and deliver the substrate  20  from the load tank  24  and the loading station  4 , referenced in FIG. 1. Because the actuator  202  can rotate the blade  94  with a first and second substrate supporting surfaces between face up and face down positions, the pivot axis  102  need not be aligned with the first axis  100  nor does the pivot joint  196  need to rotate about the pivot axis  102  through at least 180°.  
         [0049]    FIGS.  6 - 12  show schematic side views of an operational sequence for transferring a first substrate  210  and second substrate  212  between a first location  214  and a second location  216  in a CMP system. FIG. 6 is a schematic side view of the robot  72  with the blade  94  in a vertical position over the load tank  24 . In operation, a controller  130  determines that the loading station  4  needs or will need a substrate, for instance, by using a sensor or timer (not shown) to determine that a substrate has been processed or will be processed. The controller  130  activates the robot  72  to rotate the blade  94  about the pivot joint  86  to a substantially vertical position to retrieve a first substrate  210  from the load tank  24 . The first substrate  210  is held on the blade  94  by, for example, a vacuum source. The blade support arm  82  raises the blade  94  and substrate supported thereon in a vertical direction to clear the load tank  24 . The blade  94  is then moved into a horizontal position.  
         [0050]    [0050]FIG. 7 is a schematic side view of the robot  72  with the blade  94  supporting a first substrate  210  rotated to a substantially horizontal position. The blade  94  has been rotated about the pivot joint  86  by about 90° from the position referenced in FIG. 6. Also, the robot  72  has moved the blade support arm  82  and blade  94  to a position over a second substrate  212  disposed in the loading station  4 . The second substrate  212  is positioned adjacent the lower surface of the blade and chucked thereto. The robot  72  then retracts from the loading station as shown in FIG. 8.  
         [0051]    [0051]FIG. 8 is a schematic side view of the robot  72  with the blade  94  supporting the first and second substrates on the first and second substrate supporting surfaces, respectively. In this embodiment, both substrate supporting surfaces of the blade  94  are used to support the substrates  210 ,  212  by a vacuum, although other techniques of holding the substrates in place known in the art, such as mechanical grippers and adhesive films, can be used. In this view, the first substrate  210  is disposed in a top position on the blade  94  and the second substrate  212  is disposed in a bottom position on the blade  94 .  
         [0052]    The blade  94  is then rotated  180 ° about the pivot joint  86  and its axis  102  as shown in FIG. 9. As a result of the rotation, the two substrates are “flipped” so that the first substrate  210 , which was at the top position  210 ′ of the blade  94 , is relocated to the bottom of the blade. Similarly, the second substrate  212 , which was at the bottom position  212 ′, is relocated to the top of the blade  94 . The blade  94  is then rotated 180° about a first axis  100  to position the blade for re-entry into the loading station  4 , as shown in FIG. 10.  
         [0053]    The blade  94  then moves to the loading station  4  and the first substrate  210  is unloaded into the loading station  4 , as shown in FIG. 11. The second substrate  212  remains supported on the blade.  
         [0054]    The blade  94  is then moved from a horizontal position to a vertical position to align the second substrate  212  over an open position in the load tank  24  as shown in FIG. 12. Alternatively, the second substrate  212  could be moved to an inspection device and another substrate retrieved from the inspection device and loaded into the loading tank  24 . A substrate purge sequence could be performed at the inspection station as well.  
         [0055]    Variations in the orientation of the blade, substrates, robot, robot support arm, loading stations, and other system components are possible. Additionally, all movements and positions, such as “above”, “top”, “below”, “bottom”, “side”, described herein are relative to positions of objects such as the robot blade, the substrates, and the first and second locations. Accordingly, it is contemplated by the present invention to orient any or all of the components to achieve the desired movement of substrates through a processing system.  
         [0056]    While foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.