Patent Publication Number: US-2006009047-A1

Title: Modular tool unit for processing microelectronic workpieces

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation-in-part of U.S. patent application Ser. No. 10/987,049, filed Nov. 12, 2004, now pending; and claims priority from provisional U.S. Patent Application No. 60/586,833, filed Jul. 9, 2004, and provisional U.S. Patent Application No. 60/586,981, filed Jul. 9, 2004. Priority to these applications is claimed under 35 U.S.C. §§ 119 and 120, and the disclosure of these applications is incorporated herein by reference in their entirety. 
    
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      Not applicable.  
     TECHNICAL FIELD  
      The present invention is directed toward apparatus and methods for processing microfeature workpieces having a plurality of microdevices integrated in and/or on the workpieces. Particular aspects of the invention relate to a modular tool unit for heat treating microelectronic workpieces that can be combined with other processing units (e.g., wet chemical processing tools) to customize workpiece processing systems.  
     BACKGROUND OF THE INVENTION  
      In the production of semiconductor integrated circuits and other microelectronic articles from microelectronic workpieces, such as semiconductor wafers, it is often necessary to provide multiple metal layers on a substrate to serve as interconnect metallization that electrically connects the various devices on the integrated circuit to one another. The microelectronic fabrication industry has sought to use copper as the interconnect metallization by using a damascene and/or patterned plating electroplating process where holes (e.g., vias), trenches and other recesses are used to produce the desired copper patterns.  
      In a typical damascene process, a dielectric layer is applied to the wafer and recesses are formed in the wafer. A metallic seed layer and barrier/adhesion layer are then disposed over the dielectric layer and into the recesses. The seed layer is used to conduct electrical current during a subsequent metal electroplating step. Preferably, the seed layer is a very thin layer of metal that can be applied using one of several processes. For example, the seed layer of metal can be applied using physical vapor deposition or chemical vapor deposition processes to produce a layer on the order of 1000 angstroms thick or less. The seed layer can also be formed of copper, gold, nickel, palladium, and most or all other metals. The seed layer conforms to the surface of the wafer, including the recesses, or other depressed or elevated device features.  
      In single copper electroplating damascene processes, two electroplating operations are generally employed. First, a copper layer is electroplated on the seed layer to form a blanket layer. The blanket layer fills the trenches or other recesses that define the horizontal interconnect wiring in the dielectric layer. The first blanket layer is then planarized (for example, by chemical-mechanical planarization) to remove those portions of the layer extending above the trenches, leaving the trenches filled with copper. A second dielectric layer is then provided to cover the wafer surface and recessed vias are formed in the second dielectric layer. The recessed vias are positioned to align with certain of the filled trenches. A second seed layer and a second copper blanket layer are applied to the surface of the second dielectric layer to fill the vias. The wafer is planarized again to remove copper extending above the level of the vias. The vias thus provide a vertical connection between the original horizontal interconnect layer and a subsequently applied horizontal interconnect layer. Electrochemical deposition of copper films has thus become an important process step in the manufacturing of high-performance microelectronic products.  
      Alternatively, the trenches and vias may be etched in the dielectric at the same time in what is commonly called a “dual damascene” process. These features are then processed, as above, with a barrier layer, a seed layer and a fill/blanket layer that fill the trenches and vias disposed at the bottoms of the trenches at the same time. The excess material is then polished, as above, to produce inlaid conductors.  
      The mechanical properties of the copper metallization can be quite important as the metal structures are formed. This is particularly true in connection with the impact of the mechanical properties of the copper metallization during chemical mechanical polishing. Wafer-to-wafer and within wafer grain size variability in the copper film can adversely affect the polish rate of the chemical mechanical processing as well as the ultimate uniformity of the surfaces of the polished copper structures. Large grain size and low variations in grain size in the copper film are very desirable.  
      The electrical properties of the copper metallization features are also important to the performance of the associated microelectronic device. Such devices may fail if the copper metallization exhibits excessive electromigration that ultimately results in an open or short circuit condition in one or more of the metallization features. One factor that has a very large influence on the electromigration resistance of sub-micron metal lines is the grain size of the deposited metal. This is because grain boundary migration occurs with a much lower activation energy than trans-granular migration.  
      To achieve the desired electrical characteristics for the copper metallization, the grain structure of each deposited blanket layer is altered through an annealing process. This annealing process is traditionally thought to require the performance of a separate processing step at which the semiconductor wafer is subject to an elevated temperature of about 400 degrees Celsius. The relatively few annealing apparatus that are presently available are generally stand-alone batch units that are often designed for batch processing of wafers disposed in wafer boats. These batch process units increase throughput time and are not easily integrated with existing processing equipment.  
      One single wafer annealing device is disclosed in U.S. Pat. No. 6,136,163 to Cheung. This device includes a chamber that encloses cold plate and a heater plate beneath the cold plate. The heater plate in turn is spaced apart from and surrounds a heater and a lift plate. The lift plate includes support pins that project up though the heater and the heater plate to support a wafer. The support pins can move upwardly to move the wafer near the cold plate and downwardly to move the wafer near or against the heater plate. One potential drawback with this device is that the chamber encloses a large volume which can be expensive and time consuming to fill with purge gas and/or process gas. Another potential drawback is that the heater may not efficiently transfer heat to the heat plate. Still a further drawback is that the heater plate may continue to heat the wafer after the heating phase of the annealing process is complete, and may limit the efficiency of the cold plate.  
      Another single wafer device directed to the photolithography field is disclosed in U.S. Pat. No. 5,651,823 to Parodi et al. This device includes heating and cooling units in separate chambers to heat and cool photoresist layers. Accordingly, the device may be inadequate and/or too time consuming for use in an annealing process because the wafer must be placed in the heating chamber, then removed from the heating chamber and placed in the cooling chamber for each annealing cycle. Furthermore, the transfer arm that moves the wafer from one chamber to the next will generally not have the same temperature as the wafer when it contacts the wafer, creating a temperature gradient on the wafer that can adversely affect the uniformity of sensitive thermal processes.  
      None of the prior batch or single wafer annealing assemblies have been integrated into a modular system for continuous processing of workpieces to improve overall manufacturing efficiencies. One challenge of integrating different modular tool units (e.g., a load/unload module, a thermal processing unit or a wet chemical processing unit) into a single modular system is accurately calibrating the transport systems to move workpieces to/from the different units and components within the different units. Transport systems are typically calibrated by manually “teaching” the robot the specific positions of each component (e.g., station, chamber or pod). For example, conventional calibration processes involve manually positioning the robot at a desired location with respect to each chamber and pod, and recording encoder values corresponding to the positions of the robot at each of these components. The encoder value is then inputted as a program value for the software that controls the motion of the robot.  
      In addition to manually teaching the robot the specific locations within the tool, the arms and end-effectors of the robot are also manually aligned with the reference frame in which the program values are represented as coordinates. Although the process of manually aligning the components of the robot to the reference frame and manually teaching the robot the location of each component in the tool is an accepted method for setting up a tool, it is also out of specifications sooner, which results in taking the tool offline more frequently. Therefore, the downtime associated with calibrating the transport system and repairing/maintaining electrochemical deposition chambers significantly impacts the costs of operating wet chemical processing tools.  
      Another challenge of integrating independent processing tools into a system is cost-effectively manufacturing and installing the tools to meet demanding customer specifications. Many microelectronic companies develop proprietary processes that require custom wet chemical processing tools. For example, individual customers may need different combinations and/or different numbers of wet chemical processing chambers, annealing stations, metrology stations, and/or other components to optimize their process lines. Manufacturers of wet chemical and other processing tools accordingly custom build many aspects of each tool to provide the functionality required by the particular customer and to optimize floor space, throughput, and reliability. It is expensive and inefficient to manufacture a large number of different platform configurations to meet the needs of the individual customers. Therefore, there is also a need to improve the cost-effectiveness for manufacturing wet chemical processing tools.  
      The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior processing systems of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.  
     SUMMARY OF THE INVENTION  
      One aspect of the present invention is directed toward a modular thermal processing unit that can be a stand-alone unit that operates by itself, or connected to one or more modular tool units to customize the configuration of a modular tool system. The modular thermal processing unit has a dimensionally stable mounting module that enables individual modular tool units to be connected together in a manner that maintains relative positions between individual components and a transport system in a fixed reference frame defined by the mounting module. One benefit of the modular thermal processing unit of the present invention is that it can be connected with other modular tool units to produce different tool configurations. Accordingly, tool manufacturers can use a universal modular tool unit to produce different tools with different configurations of processing stations in a manner that enhances the efficiency of manufacturing custom integrated tool assemblies.  
      Another aspect of the present invention is that the transport system (i.e., robot) servicing various modular tool units can be automatically calibrated to work with individual processing components in a relatively short period of time. Because the modular tool units are dimensionally stable, the thermal processing stations, workpiece holders and wet chemical process chambers, and the transport system can be attached to the modular tool units at precise locations in a fixed reference frame. As a result, once the robot is aligned with the fixed reference frame defined by the modular tool unit, the robot can interface with the stations and process chambers without having to be manually taught the location of each specific chamber or station. Thus, the modular tool units with automated calibration systems of the present invention will reduce the downtime associated with installing and maintaining thermal and wet chemical processing tools.  
      In another aspect of the present invention, the dimensionally stable modular tool unit is a thermal processing apparatus for annealing a workpiece. The thermal processing apparatus includes a rotatable carousel assembly that is configured to support at least one, or even a plurality of workpieces. The apparatus includes a loading station, a heating station, a cooling station. A driver is coupled to the carousel assembly for rotation of the carousel assembly, wherein the workpieces are moved between the loading, heating and cooling stations. By separating the stations, heating and cooling elements may remain at relatively constant temperatures significantly improving equipment reliability and reducing the throughput time of the thermal process. Moreover, because the carousel assembly allows multiple workpieces to be processed at the same time, increased manufacturing efficiencies may be achieved.  
      In still another aspect of the present invention, the thermal processing modular tool unit is part of a integrated modular tool system including a load/unload module removeably connected to one end of the thermal processing unit and a wet chemical processing tool unit removeably connected to another end of the thermal processing tool unit. The integrated modular tool system has an automatically calibrated transport system that moves workpieces between the load/unload module, the thermal processing tool unit and the wet chemical processing tool without the need to manually teach the transport system the precise location of the components of the integrated modular tool system.  
      Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings.  
       FIG. 1  is a top plan view of a schematic diagram illustrating a modular tool unit for heat treating microelectronic workpieces. The modular tool unit includes a holding station, a thermal processing station and a transport system for moving microelectronic workpieces between a load/unload unit, the holding station and the thermal processing station.  
       FIG. 2  is a top plan view of a schematic diagram illustrating a modular tool unit for heat treating microelectronic workpieces. The modular tool unit includes a holding station, a thermal processing station and a different of a transport system for moving microelectronic workpieces between a load/unload unit, the holding station and the thermal processing station.  
       FIG. 3  is a top plan view of a schematic diagram illustrating a modular tool system for processing workpieces. The modular tool system includes a load/unload unit, a thermal processing unit, a wet chemical processing unit and a transport system for moving the workpieces between the load/unload unit, the thermal processing unit and the wet chemical processing unit.  
       FIG. 4  is an alternative embodiment of the modular tool system shown in  FIG. 3 .  
       FIG. 5A  is a rear perspective view of a modular tool unit for heat treating microelectronic workpieces according to one embodiment of the present invention.  
       FIG. 5B  is a front view of the modular tool unit for heat treating microelectronic workpieces shown in  FIG. 5A .  
       FIG. 6  is an isometric view of a portion of an automatic calibration system in accordance with an embodiment of the present invention.  
       FIG. 7  is a perspective view of an apparatus for thermally processing microelectronic workpieces according to the present invention.  
       FIG. 8  is a perspective view of the apparatus of  FIG. 7 , showing a carousel assembly operably connected to a housing of the chamber with the cover of the housing removed.  
       FIG. 9A  is a perspective view of the apparatus of  FIG. 7 , showing the underside of the housing of the chamber.  
       FIG. 9B  is a perspective view of the apparatus of  FIG. 7 , showing a base of the housing of the chamber.  
       FIG. 9C  is a perspective view of the apparatus of  FIG. 7 , showing the underside of the base of the housing.  
       FIG. 10A  is a perspective view of a cover assembly found in the apparatus of  FIG. 7 .  
       FIG. 10B  is a perspective view of the cover assembly found in the apparatus of  FIG. 7 , showing an underside of the cover assembly.  
       FIG. 11A  is a perspective view a frame of the carousel assembly found in the apparatus of  FIG. 7 .  
       FIG. 11B  is a side view a frame of the carousel assembly found in the apparatus of  FIG. 7 .  
       FIG. 12A  is a perspective view of a driver and process fluid distribution system found in the apparatus of  FIG. 7 , showing an underside of the system.  
       FIG. 12B  is a perspective view of the driver and process fluid distribution system found in the apparatus of  FIG. 7 .  
       FIG. 12C  is a plan view of the driver and process fluid distribution system found in the apparatus of  FIG. 7 .  
       FIG. 12D  is a cross-section of the driver and process fluid distribution system found in the apparatus of  FIG. 7 , taken along line D-D of  FIG. 12C .  
       FIG. 13  is an exploded view of the driver and process fluid distribution system found in the apparatus of  FIG. 7 .  
       FIG. 14  is a partial cross-section of the driver and process fluid distribution system found in the annealing chamber of  FIG. 7 , showing internal components, including a passageway, of the system.  
       FIG. 15A  is a perspective view of a heating element of the apparatus of  FIG. 7 .  
       FIG. 15B  is a perspective view of the heating element of  FIG. 15A , showing an underside of the cooling element.  
       FIG. 15C  is a plan view of the heating element of  FIG. 15A .  
       FIG. 15D  is a cross-section of the heating element of  FIG. 15A  taken along line D-D of  FIG. 15C .  
       FIG. 16A  is a plan view of the of the apparatus of  FIG. 7 .  
       FIG. 16B  is a cross-section of the apparatus of  FIG. 7  taken along line B-B of  FIG. 16A , showing a heating station.  
       FIG. 17A  is a perspective view of a cooling element of the apparatus of  FIG. 7 .  
       FIG. 17B  is a perspective view of the cooling element of  FIG. 17A , showing an underside of the cooling element.  
       FIG. 17C  is a plan view of the cooling element of  FIG. 17A .  
       FIG. 17D  is a cross-section of the cooling element of  FIG. 17A  taken along line D-D of  FIG. 17C .  
       FIG. 18A  is a plan view of the apparatus of  FIG. 7 .  
       FIG. 18B  is a cross-section of the apparatus of  FIG. 7  taken along line B-B of  FIG. 18A , showing a cooling station.  
       FIG. 19A  is a plan view of the apparatus of  FIG. 7 .  
       FIG. 19B  is a cross-section of the apparatus of  FIG. 7  taken along line B-B of  FIG. 19A , showing a loading station.  
       FIG. 20A  is a perspective view of the annealing chambers of  FIGS. 5A, 5B  and  7 , showing a front portion of the chambers in a stacked configuration.  
       FIG. 20B  is a perspective view of the annealing chambers of  FIGS. 5A, 5B  and  7 , showing a rear portion of the chambers in a stacked configuration. 
    
    
     DETAILED DESCRIPTION  
      For purposes of the present application, a microelectronic workpiece is defined to include a workpiece formed from a substrate upon which microelectronic circuits or components, data storage elements or layers, and/or micromechanical elements are formed. Micromachines or micromechanical devices are included within this definition because they are manufactured using much of the same technology that is used in the fabrication of integrated circuits. The workpieces can be semiconductive pieces (e.g., doped silicon wafers or gallium arsenide wafers), dielectric pieces (e.g., various ceramic substrates) or conductive pieces. Although the present invention is applicable to this wide range of products, the invention will be particularly described in connection with its use in the production of interconnect structures formed during the production of integrated circuits on a semiconductor wafer.  
      Various embodiments of intermediate mounting modules and modular tool units for thermal treating and wet chemical processing of microfeature workpieces are described herein in the context of depositing metals or electrophoretic resist in and/or on structures of workpieces. The modular tools and modules of the present invention, however, can be used in etching, rinsing, cleaning or other type of surface preparation processes used in the fabrication of microfeatures in and/or on workpieces.  
      Still further, although the invention is applicable for use in connection with a wide range of metal and metal alloys as well as in connection with a wide range of elevated temperature processes, the invention will be particularly described in connection with annealing of electroplated copper and copper alloys.  
       FIG. 1  is a top plan view of a schematic diagram illustrating a modular tool unit  1000  for heat treating microelectronic workpieces. The modular tool unit  1000  includes a holding station or buffer  1002 , a thermal processing station  1004  and a transport system  1006  for moving microelectronic workpieces between a load/unload module  1008 , the holding station  1002  and the thermal processing station  1004 . The modular tool unit  1000  is fixedly connected to the load/unload module  1008  by a first docking assembly  1010 . The modular tool unit  1000  (in this embodiment, an apparatus for heat treating workpieces) and the load/unload module  1008  each have a fixed reference frame. The docking assembly  1010  precisely aligns the fixed reference frame of the modular tool unit  1000  with the fixed reference frame of the load/unload module  1008 . As shown in the preferred embodiment of  FIG. 3 , the modular tool unit  1000  has a second docking assembly  1012  for fixedly connecting the modular tool unit  1000  to another module tool unit  1014  (e.g., a wet chemical processing tool).  
      The modular tool unit  1000  includes a front docking unit  1041  with front alignment elements  1042  and a rear docking unit  1043  with rear alignment elements  1044 . The docking units  1041 ,  1043  can be a rigid plate or panel, and the alignment elements  1042 ,  1044  can be pins or holes at predetermined locations in a fixed reference frame of the modular tool unit  1000 . As described more fully below, the front docking unit  1041  aligns the load/unload module  1008  with the fixed reference frame of the modular tool unit  1000 , and the rear docking unit  1043  aligns the fixed reference frame of the modular tool unit  1000  with a fixed reference frame of another modular tool unit  1014  (e.g., a main processing tool and especially a wet chemical processing tool). As such, the front and rear (or first and second) docking units  1041 ,  1043  accurately position the fixed reference frames of the main modular processing tool  1014 , the modular tool unit  1000  and the load/unload module  1008  to each other so that the transport systems  1006  (and robots  1066 ,  1069 ) can operate with the corresponding components in a modular, integrated tool system  1100  without having to manually calibrate and/or teach the robots the locations of various components.  
      The front and rear docking units  1041 ,  1043  are designed to mate with corresponding alignment elements (or fasteners) of other modular tool units, e.g., the load/unload module  1008  or the main processing unit  1014 . These mating configurations create docking assemblies  1010  (mating between load/unload module  1008  and modular tool unit  1000 ) and  1012  (mating between modular tool unit  1000  and main processing tool  1014 ). Utilizing a variety of docking assemblies and modular tools, a tool manufacturer or user can easily provide different system configurations depending on the needs of individual customers.  
      The load/unload module  1008  illustrated in  FIGS. 1-4  includes workpiece holders  1016  that hold cassettes or pods with wafers. The workpiece holders  1016  are typically arranged so that specific workpiece holders  1016  carry pods having either unfinished workpieces that have not been processed (through a main processing tool, e.g., a wet chemical processing tool  1014 ) or finished workpieces that have been processed. The load/unload module  1008  includes a docking unit  1018  and alignment elements  1019 . The docking unit  1018  can be a rigid plate or panel, and the alignment elements  1019  can be pins or holes that mate with front alignment elements  1042  of the modular tool unit  1000 . In operation, the docking unit  1018  is attached to the front docking unit  1041  of the modular tool unit  1000  so that the alignment elements  1019  are engaged with the front alignment elements  1042 . The interface between the alignment elements  1019  and the front alignment elements  1042  precisely locates the workpiece holders  1016  at predetermined locations in the fixed reference frame of the modular tool unit  1000 . As such, the transport system  1006  can accurately move in and out of cassettes or pods on the workpiece holders  1016  without having to manually teach or calibrate the transport system  1006  the specific locations of the workpiece holders  1016 .  
      The transport system  1006  shown in  FIG. 1  includes a track  1050  positioned at a known location in the fixed reference frame of the modular tool unit  1000 . The track  1050  extends laterally along a width-wise direction relative to the front of the modular tool unit  1000 . The transport system  1006  can further include a robot  1066  having a dual coaxial end-effector assembly  1068  which moves linearly along the track  1050 . Suitable robots and tracks are disclosed in U.S. Pat. Nos. 6,752,584 and 6,749,390, and U.S. Publication No. 2003/0159921, all of which are herein incorporated by reference in their entirety.  
      Turning to  FIG. 2 , there is disclosed another embodiment of the transport system  1006 . In this embodiment, there is a single stationary robot  1066  mounted to a deck or shelf  1064  of the modular tool unit  1000 . The stationary robot  1066  is comprised of an arm  1066   a  and an end-effector  1066   b . The robot  1066  moves workpieces between the workpiece holders  1016  of the load/unload module  1008  and the modular tool unit  1000 .  
      In  FIG. 3 , the transport system is comprised of first  1066  and second robots  1069 . The first robot  1066  can be configured according to the embodiments disclosed in  FIG. 1  (i.e., track  1050  and robot  1066  which moves linearly along the track) or  FIG. 2  (i.e., the robot  1066  is mounted to a shelf or deck), and moves workpieces between the load/unload module  1008  and the modular tool unit  1000 . The second robot  1069  moves linearly along a track  1050  mounted on another modular tool unit  1014  which is fixedly attached to modular tool unit  1000 . Preferably, the second robot  1069  has a dual coaxial end-effector assembly  1068 . The second robot  1069  moves workpieces between modular tool units  1000 ,  1014 . For example, the first robot  1066  will take unprocessed workpieces from the workpiece holders  1016  and place them in the holding station  1002  of modular tool unit  1000 . The second robot  1069  then takes the unprocessed workpieces from the holding station  1002  and places them into one or more processing stations  1070 . When the workpieces are processed, robot  1068  removes them from the processing stations  1070  and places them into the thermal processing station  1004  or the holding station  1002 . Robot  1066  moves the workpieces between the thermal processing station and the holding station, and ultimately unloads the processed workpieces into the load/unload module  1008 . The dual robot configuration illustrated in  FIG. 3  increases throughput efficiency and is preferred. In another embodiment illustrated in  FIG. 4 , the transport system is comprised of a single robot  1067  that moves linearly along track  1050  and services the load/unload module  1008  and modular tool units  1000 ,  1014 .  
       FIG. 4  is a top plan view of an integrated tool assembly  1100  in accordance with another embodiment of the present invention. The integrated tool assembly  1100  is similar to the integrated tool assembly  1100  in  FIG. 3 , but the integrated tool assembly  1100  in  FIG. 4  has an intermediate modular tool unit  1000  without a separate transport system. As such the main processing tool unit  1014  and the intermediate modular tool unit  1000  share a common track  1050  and a common robot  1067 .  
      Turning to  FIGS. 1-3 ,  5 A and  5 B, a calibration unit  1005  can be mounted on a deck  1030  or platform (not shown) of the modular tool unit  1000 . The calibration unit  1005  is fixed at a known location in the reference frame of the modular tool unit  1000 . The calibration unit  1005  automatically determines the position of robot  1066  and the end-effector  1068  relative to the fixed reference frame of the modular tool unit  1000  and corrects any misalignment of the robot  1066  and the end-effector  1068  so that the transport system  1006  can accurately interface with the workpiece holders  1016  and the holding and thermal processing stations  1002 ,  1004  without having to manually teach the robot  1066  the location of each one of the components in the modular tool unit  1000 .  
      Referring to  FIG. 6 , there is disclosed a calibration unit  1005  to be used in a combination with a robot  1066 , which is mounted on a track, e.g. as shown in  FIGS. 1 and 3 , in one embodiment of the present invention. Calibration unit  1005  is used in combination with distance measuring devices  1005   a ,  1005   b  and  1005   c  that are mounted perpendicular, parallel and vertical to the track. To initial set the calibration unit, first arm of the robot  1066  touches the distance measuring device that is perpendicular to the track  1005   a . The robot  1066  then moves until it is able to touch the other side of the first arm to the distance measuring device that is perpendicular to the track  1005   a . At this point a waist zero location is calculated and set. The robot  1066  then moves to touch the first edge of a workpiece gripped in the first end effector  1068  to the distance measuring device that is perpendicular to the track  1005   a . The robot  1066  then moves to touch the first edge of a workpiece gripped in the second end effector  1068  to the distance measuring device that is perpendicular to the track  1005   a . The robot  1066  then rotates the arm 180 degrees and moves to touch the second edge of the workpiece gripped in the first end effector  1068  to the distance measuring device that is mounted perpendicular to the track  1005   a . The robot  1066  then touches the second edge of the workpiece gripped in the second end effector  1068  to the distance measuring device that is mounted perpendicular to the track  1005   a . The robot  1066  then moves to touch the bottom of the arm to the distance measuring device mounted vertically  1005   c  in order to set the zero point for the vertical axis. The last move is to bring the arm to a set angle and then move the track so that the arm will touch the distance measuring device that is parallel to the track  1005   b  in order to set the zero point of the track axis. In this manner, a fixed reference frame of the modular tool unit  1000  is set.  
      The calibration unit  1005  is set or zeroed in a similar manner for the embodiment where the robot  1066  is not mounted on a track, e.g., the embodiment illustrated in  FIG. 2 , but instead is mounted on a shelf or platform. The layout of the distance measuring devices is different, however, due to the radial nature of the robot  1066  used in such an embodiment. It is necessary not to obstruct the area in which the robot could be operated. Such a layout is disclosed in  FIG. 5A . One distance measuring device  1005   a  is mounted tangent to the arc the first arm travels that is used to zero the first arm. A second distance measuring device  1005   b  is mounted perpendicular to the arc the first arm travels in order to zero the second arm and the end effector of the robot. And a third distance measuring device  1005   c  is oriented vertically to zero the vertical axis on the robot. In this manner, a fixed reference frame of the modular tool unit  1000  can be set.  
      Suitable calibration units and calibration methods for use with the present invention are disclosed in U.S. patent application Ser. Nos. 10/860,385 and 10/861,240, which are incorporated herein by reference in their entirety.  
      It should be understood that modular tool unit  1000  and load/unload module  1008  can operate as a stand alone system as shown in  FIGS. 1 and 2 . However, with reference to  FIGS. 3 and 4 , in a preferred embodiment of the present invention, the modular tool unit  1000  is fixedly attached to another module tool unit  1014 , preferably a main processing unit. In one embodiment, the main processing unit  1014  is a wet chemical processing tool that includes a plurality of wet chemical process stations  1070 . The process stations  1070  can be electrochemical process stations (such as would include electroless deposition chambers, electroplating deposition chambers or electroetch/electropolish chambers), rinsing/prewetting and/or drying stations (such as would include process chambers for rinsing or prewetting wafers prior to or following processing in the electrochemical process chambers or for drying wafers following processing), chemical etching stations (such as would include process chambers for etching the backside and/or the edge of wafers following processing in the electrochemical process chambers), or other suitable wet chemical processing stations. Suitable wet chemical processing stations  1070  and associated processing chambers are disclosed in: (1) U.S. Pat. Nos. 6,749,390, 6,660,137, 6,632,292, 6,565,729, 6,423,642 and 6,413,436, all of which are herein incorporated by reference in their entirety; (2) U.S. patent application Publication Nos. 2003/0068837, 2003/0070918, 2002/0125141, 2003/0127337 and 2004/0013808; and, (3) U.S. patent application Ser. No. 10/859,749 filed Jun. 3, 2004, all of which are incorporated herein by reference in their entirety.  
      An exemplary integrated tool configuration for forming copper interconnects on microelectronic workpieces would provide several electrochemical copper deposition stations and one or more workpiece edge etching stations, in addition to a workpiece annealing module such as module  1000 . In the exemplary tool, the workpiece edge etching station(s) could be located immediately adjacent to the module  1000 , such as one such etching station on either side of track  1050 . In the exemplary tool, each edge etching station could include the capability to etch the workpiece backside in addition to the workpiece marginal edge. In the exemplary tool, the electrochemical deposition stations could be located on either side of track  1050  beyond the edge etching station. In such a tool, referring to  FIG. 3 , a workpiece processing sequence could be as follows: the workpiece would be removed from a workpiece holder  1016  by robot  1066  and delivered to the holding station  1002 , removed from the holding station  1002  by robot  1069  and delivered first to one of the electrochemical deposition stations at the opposite end of tool  1014  for copper interconnect deposition, and then removed from the deposition station by robot  1069  and delivered to one of the edge and/or edge/backside etching process stations for removal of copper from the marginal edge (and possibly the backside) of the workpiece, and then removed from the edge etching station by robot  1069  and delivered to the annealing station  1004  for thermal annealing of the copper deposits, and finally removed from annealing station  1004  by robot  1066  and delivered to one of the workpiece holders  1016  for removal from the integrated tool. Alternately, a workpiece could be removed from an edge etching station by robot  1069  and delivered to the holding station  1002 , and then removed from holding station  1002  by robot  1066  and delivered to the annealing station for thermal annealing, and then removed by robot  1066  from the annealing station and delivered to the workpiece holder  1016 .  
      Main processing tool  1014  also includes a docking unit  1018  and alignment elements  1019 . As discussed above, the docking unit  1018  can be a rigid plate or panel, and the alignment elements  1019  can be pins or holes that mate with rear alignment elements  1044  of the modular tool unit  1000 . In operation, the docking unit  1018  is attached to the rear docking unit  1042  of the modular tool unit  1000  so that the alignment elements  1019  are engaged with the front alignment elements  1042 . The interface between the alignment elements  1019  of the main processing tool  1014  and the rear alignment elements  1044  of the modular tool unit  1000  precisely locates the components of the main processing tool (e.g., wet chemical deposition stations  1070  or other surface preparation stations) at predetermined locations in the fixed reference frame of the modular tool unit  1000 . As such, the transport system  1006  can accurately move workpieces from the modular tool unit  1000  to the process stations  1070  of the main processing tool  1014  without having to manually teach or calibrate the transport system  1006  the specific locations of the process stations  1070 .  
      Turning to  FIGS. 7-20A  and B, a preferred embodiment of the thermal processing station  1004  of the modular tool unit  1000  of the present invention will now be described. A preferred process for thermally processing microelectronic workpieces W will also be described. With specific reference to  FIGS. 7 and 8 , the apparatus, hereinafter called a “carousel annealer”  10  includes a housing  20 , a carousel assembly  100  positioned within the housing  20 , a driver and process fluid distribution system  200 , a heating element  300  and a cooling element  400 . As explained below, the carousel annealer  10  has multiple stations for thermal processing of workpieces W. Although shown as a stand alone unit in  FIG. 7 , the carousel annealer  10  can be positioned within a larger tool or module for high-speed processing of workpieces W.  
      The housing  20  of the carousel annealer  10  generally comprises a cover  22  that is removeably connected to a base  24 . The cover  22  has a side wall component  26  joined with a plurality of fasteners  27  to a top wall component  28 . A portion of the base  24  has a stepped outer edge or lip  25  that facilitates the connection with the side wall  26  and that causes the periphery of the base  24  to have a staggered appearance. The cover  22  has at least one opening or bay  30  that provides access to the internal components of the carousel annealer  10 . Preferably, the cover  22  has both a first opening  30  that provides access for loading of the workpiece W and a second opening  32  that provides access for unloading of a processed workpiece W. Alternatively, the carousel annealer  10  has a single opening whereby the workpieces W are loaded in and unloaded from that opening.  
      As shown in  FIG. 9A , the base  24  of the housing  20  has a number of openings, including a pair of centralized openings  40   a, b  configured to receive an extent of the drive and process fluid distribution system  200 . Specifically, the primary centralized opening  40   a  receives a portion of the drive components of the system  200  and the secondary centralized opening  40   b  receives a portion of the process fluid components of the system  200 . The base  24  further includes a first opening  42  configured to receive a heating element  300  (see  FIG. 16B ), and a second opening  44  configured to receive a cooling element or chuck  400  (see  FIG. 18B ). At least one locating shaft  46  depends from a lower surface  24   a  of the base  24  to facilitate the installation of the carousel annealer  10  into a larger tool or module. The locating shaft  46  is configured to receive a fastener inserted in an opening  47  in the upper surface of the  24   b  of the base  24 . The base  24  may also include a pair of recessed areas  48  for securement of an actuator  50  that extends from a housing  51  substantially perpendicular to an upper surface  24   b  of the base  24 . An alternate version of the base  24  is shown in  FIGS. 9B  and C, wherein the drive and process fluid distribution system  200  and two actuators  50  are installed in an alternate base  24 . The alternate base  24  lacks the recessed areas  48  that are utilized in the securement of the actuators  50 . Each actuator  50 , such as an air cylinder, includes a shaft  52  with a pedestal  54  that is raised to engage an extent of a control arm  128  (see  FIG. 8 ) of the cover assemblies  120 ,  122 ,  124  during operation of the apparatus  10 . Preferably, the carousel annealer  10  includes two air cylinders  50  since the cover assemblies  120 ,  122 ,  124  are elevated and the workpieces W are accessed and handled by a separate robot (not shown) at the loading station  505  and the cooling station  405 . Alternatively, the carousel annealer  10  includes a single air cylinder  50  whereby the workpieces W are access and handled at a single station  405 ,  505 .  
       FIG. 8  shows the base  24  of the housing  20  and the carousel assembly  100 , however, the cover  22  has been removed. The carousel assembly  100  rotates above the base  24  and about a central vertical axis extending through a centralized opening  40   a  of the base  24 . Referring to  FIGS. 8 and 11 A,B, the carousel  100  includes a frame  102  that includes at least one workpiece receiver  104 . In one embodiment, the frame  102  includes a first workpiece receiver  104 , a second workpiece receiver  106 , and a third workpiece receiver  108 . The receivers  104 ,  106 ,  108  are configured to removeably receive a workpiece W during operation of the apparatus  10 . The receivers  104 ,  106 ,  108  support the workpieces W in a substantially horizontal arrangement with respect to the frame  102 . Preferably, each receiver  104 ,  106 ,  108  has a plurality of fingers or tabs  110  that extend radially inward from an inner edge  112  to support a workpiece W. In one embodiment, the tabs  110  are circumferentially spaced along the edge  112  of the receivers  104 ,  106 ,  108  and engage the lower (non-device) side of the workpiece W. Although shown as having a semi-circular configuration, additional material could be added to the receivers  104 ,  106 ,  108  whereby they would have a circular configuration.  
      The frame  102  of the carousel  100  also includes a rib arrangement  114  that is raised vertically from an upper surface  102   a  of the frame  102 . The frame  102  has external segments  102   b  and a depending segment  102   c  (see  FIG. 11B ). The rib arrangement  114  is generally configured to increase the rigidity and strength of the frame  102 . The rib arrangement  114  has three segments  114   a, b, c  wherein each segment extends radially outward from a central opening  116  in the frame  102  and between a pair of receivers  104 ,  106 ,  108 . The central opening  116  is positioned at the hub  117  of the frame  102  and accommodates an extent of the driver and process fluid distribution system  200 , primarily a manifold  210  of the system  200 . The receivers  104 ,  106 ,  108  are radially positioned about the central opening  116  in an approximately 120 degree relationship. When the carousel assembly  100  is assembled, the central opening  116  is cooperatively positioned with the centralized opening  40   a  of the base  24  and the central axis that extends there through.  
      The carousel assembly  100  further includes at least one cover assembly  120  that is movable between a closed position P C  (see  FIG. 8 )and an open position. Referring to  FIG. 8 , the carousel assembly  100  includes a first cover assembly  120  operably associated with the first workpiece receiver  104 , a second cover assembly  122  operably associated with the second workpiece receiver  106 , and a third cover assembly  124  operably associated with the third workpiece receiver  108 . For example, the first cover assembly  120  remains positioned over the first receiver  104  and the second cover assembly  122  remains positioned over the second receiver  106  during rotation of the carousel assembly  100 . Referring specifically to  FIGS. 8 and 10 A, B, each cover assembly  120 ,  122 ,  124  includes a cover plate  126 , a control arm  128 , a mounting bracket  130 , and a purge line  131 . The cover plate  126  is dimensioned to overlie or cover the receivers  104 ,  106 ,  108  when the cover assembly  120 ,  122 ,  124  is in the closed position P C . In the closed position P C  of  FIG. 8 , the cover plate  126  is positioned near external segments  102   b  of the frame  102 . In an open position (not shown), the cover assembly  120 ,  122 ,  124  is elevated with respect to the frame  102  to permit insertion of a workpiece W into the receiver  104 ,  106 ,  108 . Upon completion of the thermal processing steps, the cover assembly  120 ,  122 ,  124  is elevated in the open position to removal of a workpiece W from the receiver  104 ,  106 ,  108 . The underside of the cover assembly  120 ,  122 ,  124  is shown in  FIG. 10B , wherein the plate  126  has a circumferential lip  125  and a central opening  127  that, as explained below, receives process fluid during the thermal processing of the workpiece W. Therefore, in the closed position P C , the cover assembly  120 ,  122 ,  124 , the workpiece W and the frame  102  define an internal cavity that receives process fluid during operation of the carousel annealer  10  to remove impurities from the cavity.  
      The control arm  128  pivotally connects the cover assembly  120 ,  122 ,  124  to an extent of the rib arrangement  114  with a mounting bracket  130 , preferably near the terminus of the rib segments  114   a, b, c.  The control arm  128  is a multi-bar linkage system with a plurality of links  132  extending between the mounting bracket  130  and a distribution block  134 . The control arm  128  has a pair of external links  132   a  , b pivotally connected to outer walls of the bracket  130  and an internal link  132   c  connected to a short link  132   d  that is affixed to an intermediate portion of the bracket  130 . The distribution block  134  is affixed to an upper surface  126   a  of the cover plate  126  and is in fluid communication with the central opening  127 . The control arm  128  also has a curvilinear segment  136  that extends from the block  134  beyond the periphery of the cover plate  126 . A terminal end  138  of the curvilinear segment  136  has a fitting  140  secured by a nut  142  wherein the fitting  140  is adapted to engage the air cylinder  50 , preferably the pedestal  54 , to move the cover assembly  120 ,  122 ,  124  to the open position P O .  
      A fluid line  131  of the cover assembly  120 ,  122 ,  124  extends between the distribution block  134  and the manifold  210  of the driver and process fluid distribution system  200 . The driver and process fluid distribution system  200  is affixed to the carousel  100  at the rib arrangement  114  by at least one fastener  115 . As explained below, the manifold  210  is in fluid communication with the driver and process fluid distribution system  200 . The manifold  210  includes three outlet or discharge ports  212  that are connected to a first end  131   a  of the purge line  131 . A second end  131   b  of the fluid line  131  is in fluid communication with the distribution block  134 . In general terms, process fluid is delivered from the manifold  210 , through the fluid lines  131  and to the blocks  134  for further distribution into the opening  127  of the cover plate  126  and then to the workpiece W supported by the receivers  104 ,  106 ,  108 .  
      As briefly explained above, the base  24  of the housing  20  has a number of openings  40   a , b configured to receive the driver and process fluid distribution system  200 . Referring to FIGS.  9 A-C,  12 A-D and  13 , the driver and process fluid distribution system  200  features a process fluid distribution assembly  205  and a driver assembly  215 , wherein the assemblies  205 ,  215  are connected to a mounting plate  220 , which in turn is connected to the base  24 . Alternatively, the mounting plate  220  is omitted and the assemblies  205 ,  215  are fastened directly to the base  24  of the housing  20 . In one embodiment, the process fluid distribution assembly  205  and the driver assembly  215  are integrated units. In another embodiment, the process fluid distribution assembly  205  is distinct and separate from the driver assembly  215 . The process fluid assembly  205  is designed to supply process fluid to workpieces W at the loading, heating, and/or cooling stations  305 ,  405 ,  505 . The process fluid distributed by the system  200  can purge the loading, heating, and cooling stations  305 ,  405 ,  505  of oxygen or impurities. Also, the process fluid distributed by the system  200  can aid with the thermal processing of the workpiece W in the loading, heating, and cooling stations  305 ,  405 ,  505 . The process fluid can be an inert gas such as argon or helium, a non-oxidizing gas such as nitrogen, a reducing gas such as hydrogen, an oxidizing gas such as oxygen or ozone, or any combination thereof. Preferably, the process fluid comprises approximately 90-97% by volume argon and approximately 3-10% by volume hydrogen, or approximately 90-98% by volume nitrogen and approximately 2-10% by volume hydrogen. Furtherrnore, the process fluid can be any fluid that aids with the removal of impurities and/or aids with the thermal processing of workpieces W. The driver assembly  215 , through an indexing drive motor  234 , precisely rotates the carousel assembly  100  above the base  24  and between thermal processing stations.  
      Once installed in the base  24 , an extent of the driver and process fluid distribution system  200  is positioned above the base  24  and a remaining extent of the system  200  is positioned below the base  24 . A bracket  217  is connected to the lower surface  220   a  of the mounting plate  220  with fasteners  217   a  and at least one pin dowel  217   b  (see  FIG. 13 ). The bracket  217  is adapted to provide support to components of the process fluid assembly  205  during operation of the carousel assembly  100 . A cover  219  is removeably connected to the mounting plate  220  by at least one fastener  221  to enclose the lower components of the driver and process fluid distribution system  200 , meaning those components positioned below the base  24 .  
      As shown in FIGS.  12 A-D and  13 , the process fluid distribution assembly  205  generally includes the manifold  210  with outlet ports  212  that are in fluid communication with the purge lines  131 , a base  222  with a flange  224  for connection to the mounting plate  220 , and a generally cylindrical input sleeve  226  that receives process fluid from the supply lines  228 . In the embodiment shown in FIGS.  9 A-C and  13 , the manifold  210  and the mounting plate  220  are omitted, however, the flange  224  of the base  222  is directly connected to a recessed mounting region of the centralized opening  40   b . While the base  222  and the input sleeve  226  are stationary components of the process fluid assembly  205 , the manifold  210  rotates about a substantially vertical axis defined by a shaft  236  during operation of the carousel assembly  100 . The manifold  210  has a shoulder  211  that overlies an upper region of the sleeve  226  after the manifold  210  is installed (see  FIG. 12D ). Furthermore, the manifold has a depending segment  210   a  that extends into the sleeve  226 .  
      As shown in  FIGS. 12B and 13 , a plurality of supply lines  228  are connected to the input sleeve  226 , wherein the lines  228  provide a quantity of process fluid, primarily a non-oxidizing gas, to the sleeve  226  and the manifold  210  for distribution through the fluid lines  131  to the cover plates  126 . The supply lines  228   a, b, c  are removeably connected to the inlet opening  227   a, b, c  of the sleeve  226  (see  FIG. 12A ). The sleeve  226  has a plurality of internal annular or ring-shaped channels  229   a, b, c  wherein each channel  229  is in fluid communication with an inlet opening  227   a, b, c . Preferably, the channels  229   a, b, c  are flush with an inner wall of the sleeve  226 . Referring to  FIG. 14 , the rotatable manifold  210  has a plurality of internal channels  230   a, b, c  that extend between upper and lower segments of the manifold  210  and that are in fluid communication with the annular channels  229   a, b, c  of the sleeve  226 . Preferably, the channels  230   a, b, c  in the manifold  210  include two horizontal runs—a lower run  230   1  and an upper run  230   2  and a vertical run  230   3 —to ensure fluid communication with the annular channels  229   a, b, c  and the discharge ports  212   a, b, c . For example and as shown in  FIG. 14 , the lower run  230   a   1  of the channel  230   a  is in fluid communication with the annular channel  229   a , and the upper run  230   a   2  is in fluid communication with the discharge port  212   a . The annular channels  229  in the sleeve  226  and the internal channels  230  of the manifold  210  define an air or fluid passageway  231   a, b, c  for the flow of process fluid delivered by the supply lines  228   a, b, c  to the inlet openings  227   a, b, c . Accordingly, each passageway  231   a, b, c  extends from the inlet opening  227   a, b, c  through the annular channel  229   a, b, c,  then the internal channel  230   a, b, c  and to discharge port  212   a, b, c . The passageways  231   a, b, c  enable the process fluid distribution system  205  to delivery process fluid to the workpiece W while it is supported by any of the receivers  104 ,  106 ,  108  at the loading station  505  (see  FIG. 19B ) or as the carousel assembly  100  is rotated from the station  505  to the heating station  405 . In another embodiment, the passageways  231   a, b, c  enable the process fluid distribution system  205  to delivery process fluid to the workpiece W while it is supported by any of the receivers  104 ,  106 ,  108  at each of the loading, heating and cooling stations  505 ,  305 ,  405 .  
      The process fluid assembly  205  further includes means for sealing the process fluid supplied to the sleeve  226 . The sealing means comprises a plurality of gaskets or sealing rings  232 , for example, O-rings, positioned about the channels  230  in the sleeve  226  (see  FIGS. 12C, 13  and  14 ). In one embodiment, the process fluid assembly  205  includes three fluid passageways  231   a, b, c  wherein each passageway  231   a, b, c  is in fluid communication with a single, distinct discharge port  212   a, b, c . This configuration ensures that a precise amount and/or type of process fluid will be delivered by the passageway  231   a, b, c  to each discharge port  212   a, b, c  for further distribution to specific components of the carousel assembly  100 . As a result, the components of the carousel assembly  100  downstream of the passageway  231   a, b, c  can be selectively supplied with process fluid for the workpiece W. In another embodiment, the process fluid assembly  205  includes a single passageway  231  through the sleeve  226  and manifold  210  to deliver process fluid to all of the discharge ports  212   a, b, c.    
      One of skill in the art recognizes that the formation of a passageway  231   a, b, c  is not dependent upon the angular position of the manifold  210  with respect to the sleeve  226 , since the annular channel  229   a, b, c  has a continuous, uninterrupted configuration. In another version of the process fluid assembly  205 , the channel  229   a, b, c  has a short, non-annular configuration. Accordingly, a passageway  231   a, b, c  for process fluid will be only formed when the internal channel  230   a, b, c,  primarily the lower run  230   1 , is aligned or cooperatively positioned with the channel  229   a, b, c.  In yet another version, the channel  229   a, b, c  has a discontinuous or segmented configuration whereby the passageway  231   a, b, c  will only be formed when the lower run  230   1  is cooperatively positioned with the channel  229   a, b, c.    
      As explained in greater detail below, the driver assembly  215  rotates the carousel assembly  100 , including three cover assemblies  120 ,  122 ,  124 , the control arms  128 , and the frame  102 , between the loading, heating and cooling stations  305 ,  405 ,  505 . Alternatively, the loading station  505  is omitted and the driver assembly  215  rotates the carousel assembly  100  between the heating and cooling stations  405 ,  505 . The driver assembly  215  includes an indexing drive motor or driver  234  with a depending shaft  235 , the longer shaft  236  extending through an opening in the mounting plate  220 , a first pulley  238 , a second pulley  239 , and a timing belt  240 . In general terms, the pulleys  238 ,  239 , the belt  240  and the shaft  236  are operably connected to the indexing motor  234  to drive the manifold  210 . The drive mechanism  234  further includes a first bearing  242  positioned within a recess of the mounting plate  220 , a second bearing  244  positioned in a recess of the bracket  217 , and a pair of ring seals  246  located at opposed ends of the shaft  236 . As shown in  FIG. 12A , the second bearing  244  has an open face whereby the end wall  236   a  of the shaft  236  is visible. A plate seal  248  is affixed to an upper wall in a recess  250  of the mounting plate  220  by fasteners  252  and a smaller seal  254  is positioned between the first bearing  242  and the plate seal  248 .  
      As shown in  FIGS. 12A and 13 , to aid with the operable connection between the pulleys  238 ,  239  and the timing belt  240 , the driver assembly  215  features a tensioner assembly which includes a tensioning arm  256  and a bearing  258  that engages the timing belt  240  during its operation. The tensioner assembly also includes a first fastener  260  that pivotally connects the arm  256  to the lower surface  220   a  of the mounting plate  220 , and a second fastener  262  and washer  264  that rotatably secures the bearing  258  to the arm  256 . The tensioner assembly further includes a coil spring  266  for biasing the tensioning arm  256  towards the timing belt  240  whereby the bearing  258  rotatably engages the belt  240 . The coil spring  266  is secured at its first end to a retainer  268  affixed to the tensioning arm  256  and at its second end by a pin  270  affixed to the mounting block plate  220 .  
      The driver assembly  215  and the process fluid assembly  205  feature a compact design, which permits a significant portion of the driver and process fluid distribution system  200  to be packaged between the base  24  of the housing  20  and the frame  102  of the carousel assembly  100 . Due to the indexing drive motor  234 , the driver assembly  215  precisely drives or rotates the manifold  210  and the carousel assembly  100 , including the cover assemblies  120 ,  122 ,  124 , and the frame  102 , above the base  24  and between the radially positioned stations  305 ,  405 ,  505  for thermal processing of the workpieces W. The remaining components of the process fluid distribution system, including the base  222  and the sleeve  226 , are not rotated and remain stationary with respect to the base  24 .  
      Referring to FIGS.  15 A-D and  16 A, B, the carousel annealer  10  includes an electrically-powered heating element or chuck  300  that transfers a sufficient quantity of heat to the workpiece W during thermal processing. In one embodiment, the workpiece W is rotated by the carousel assembly  100  from a loading position P 0  at the loading station  505  (see  FIG. 19B ) to a heating station  305 . The heating station  305  is a region of the carousel annealer  10  that is defined by the heating element  300 , a portion of the carousel assembly  100  (primarily the extent of the plate  102  positioned above the heater element  300 , including the tabs  110  that support the workpiece W), and the cover plate  126  of the a cover assembly  120 ,  122 ,  124 . Described in a different manner, the driver assembly  215  rotates the workpiece W supported in the carousel assembly  100  from the loading position P 0  to a first position P 1  (see  FIG. 16B ) for thermal processing, wherein in the first position P 1  the workpiece W is positioned directly above the heating element  300 . Through rotation of the carousel assembly  100 , the workpieces W can be sequentially placed in the first position P 1 . In another embodiment, the loading station  505  and the heating station  305  are combined whereby the loading position P 0  and the first position P 1  are consolidated causing the workpiece W to be loaded and heated by the heating element  300  in the same general location.  
      The heating element  300  has a generally cylindrical configuration and as shown in  FIGS. 16A  and B, is positioned within the opening  42  in the base  24  of the housing  20  to define an initial position. Furthermore, the heating element  300  is positioned substantially between the base  24  and the frame  102  of the carousel assembly  100 , while being positioned radially outward of the driver and process fluid distribution system  200 . The heating element  300  generally comprises an upper portion  302  with a heating surface  304  that is placed in thermal contact with the workpiece W, an intermediate portion  306  with a insulated cavity  308 , and a lower portion  310  that includes an actuator  312 , such as a bellows assembly, that moves or elevates the heating element  300  from the initial position to a use position for thermal processing of the workpiece W. Upon completion of the thermal processing of a particular workpiece W, the actuator  312  returns the heating element  300  to its initial position.  
      The upper portion  302  employs an electrically-powered resistive heater  303  and has a circular periphery  314 . A recessed annular ledge  316  is positioned radially inward of the periphery  314 . In one embodiment the heating surface  304  is located radially inward of the ledge  316 , while in another embodiment, the heating surface  304  extends to the periphery  314  of the upper portion  302 . The heating surface  304  is cooperatively dimensioned with the workpiece W to permit thermal processing of the workpiece W. The heating surface  304  includes an arrangement of vacuum channels  318  that are positioned about a central opening  320  of the heating surface  304 . A passageway  322  extends transverse to the heating surface  304  from the central opening  320  to an internal fitting  324 . Vacuum air is supplied through the fitting  324  and the passageway  322  to the vacuum channels  318  wherein the vacuum air helps to maintain a vacuum seal engagement between the heating element  300  and the workpiece W. A vacuum air delivery mechanism, including an external fitting  326 , extends through the intermediate and lower portions  306 ,  310  and is in fluid communication with the internal fitting  324 . The vacuum air delivery mechanism is coupled to a vacuum source (not shown) that supplies the vacuum air used during annealing of the workpiece W.  
      Preferably, the upper portion  302  also includes a plurality of depressions  328  that extend radially inward from the periphery  314 . The depressions  328  are cooperatively positioned and dimensioned to receive an extent of the tabs  110  of the frame  102  of the carousel assembly  100  when the heating element  300  is elevated by the bellows assembly  312  to the use position and the heating surface  304  engages the workpiece W. The depressions  328  disengage the tabs  110  when the thermal processing is completed and the bellows assembly  312  lowers the heating element  300  to its initial position. Alternatively, the depressions  328  are omitted and tabs  110  engage a portion of the heating surface  304  when the heating element  300  is elevated. To secure the upper portion  302  to the heating element  300 , a plurality of fasteners  330  are inserted through slots  332  in the side wall  334  of the upper portion  302 .  
      The intermediate portion  306  of the heating element  300  includes a cavity  308  within a side wall  307  wherein the cavity  308  includes conventional insulation. The intermediate portion  306  also includes a bottom wall  336  that is secured to a top wall  338  of the lower portion  310  by fasteners  340  (See  FIG. 15D ).  
      The actuator or bellows assembly  312  is generally positioned in the lower portion  310  of the heater element  300 . The bellows assembly  312  moves the upper and intermediate portions  302 ,  306 , including the heating surface  304 , from the initial position towards the frame  102  of the carousel assembly  100  and to the use position. In the initial position and as shown in  FIG. 16B , there is a clearance C between the heating surface  304  and the workpiece W. In the use position, the heating element  300  is in thermal engagement with the workpiece W to enable heat transfer to the workpiece W. Preferably, in the use position, the heating surface  304  is in direct contact with the non-device side of the workpiece W thereby eliminating the clearance C. Alternatively, in the use position, the heating surface  304  is in close proximity to the non-device side of the workpiece W thereby significantly reducing the clearance C. When the bellows assembly  312  lowers the heating element  300  from the use position to the initial position, the clearance C is present.  
      The bellows assembly  312  includes the top wall  338 , a bottom wall  344 , and a bellow  346 . In one embodiment, the bellow  346  has a cylindrical configuration and the bottom wall has a central core  345  that is positioned within the bellow  346 . In another embodiment, the bellows assembly  312  includes a number of bellows  346  circumferentially spaced with respect to the bottom wall  336 . Referring to  FIG. 16B , at least one fastener  345  extends through the bottom wall  344  and the base  24  to secure the heating element  300  to the carousel annealer  10  above the opening  42  in the base  24 . The bellows assembly  312  further includes a bushing  348  within a cover  350  affixed to the bottom wall  344  by fasteners  352 . A sealing ring  354 , preferably an O-ring, configured to seal the cover  350  with respect to the bottom wall  344  is positioned within a cavity of the cover  350 . The bushing  348  is affixed to the bottom wall  344  by fasteners  356 , and has a central opening with a guide sleeve  358  that sliding engages an extent of a guide shaft  360 . A stop portion  360   a extends transversely to a main body potion  360   b of the shaft  360 . The shaft  360  is coupled to the top wall  338  at an upper portion  360 c by fasteners  362 . In operation of the bellow assembly  312  and while the heating element  300  is moved between the initial and use positions, the guide shaft  360  slides through the sleeve  358  and towards the heating surface  304 .  
      When the bellow assembly  312  moves the upper and intermediate portions  302 ,  304  a sufficient distance to bring the heating element  300  to the use position, vacuum air is supplied to the internal fitting  324  for delivery through the central opening  320  in the heating surface  304 . Similarly, when the heating element  300  reaches the use position, the heating element  300  is activated to begin a heating cycle for the annealing of the workpiece W. Referring to  FIG. 15B , the bellows assembly  312  includes at least one inductive sensor  364  which extends though a side wall  353  of the cover  350  and that monitors the position of the heater element  300 , including the shaft  360 . The sensor  364 , in connection with the control system  600 , prevents rotation of the carousel assembly  100  until the bellows assembly  312  returns the heating element  300  to its initial position (see  FIG. 16B ). In operation, the sensor  364  and the control system ensure the timely rotation of the carousel assembly  100 , the delivery of vacuum air, and the activation of the heating element  300  and the heating cycle.  
      Referring to FIGS.  17 A-D and  18 A, B, the carousel annealer  10  includes a cooling element or chuck  400  that cools the workpiece W during a post-heating stage of thermal processing. After the heating stage is completed, the workpiece W is rotated by the carousel assembly  100  from the heating station  305  to a cooling station  405  having the cooling element  400 . The cooling station  405  is a region of the carousel annealer  10  that is defined by the cooling element  400 , a portion of the carousel assembly  100  (primarily the extent of the plate  102  positioned above the cooling element  400 , including the tabs  110  that support the workpiece W), and the cover plate  126  of a cover assembly  120 ,  122 ,  124 . Described in a different manner, the driver assembly  215  rotates the workpiece W supported in the carousel assembly  100  from the first position P 1  to a second position P 2  (see  FIG. 18B ) for thermal processing. In the second position P 2  the workpiece W is positioned substantially above the cooling element  400 . Through rotation of the carousel assembly  100 , the workpieces W are sequentially placed in the second position P 2  for thermal processing by the cooling element  400 . As shown in  FIG. 18B , the workpiece W is supported in the second position P 2  by the tabs  110  of the frame  102 . Preferably, the workpiece W is removed or unloaded from the carousel assembly  100  at the second position P 2  through the second opening  32  upon completion of the cooling cycle. Alternatively, the workpiece W is rotated from the cooling station  405  to the loading station  505  or the loading position P 0  where it is unloaded prior to the loading of an unprocessed workpiece W.  
      The cooling element  400  has a generally cylindrical configuration and as shown in  FIGS. 18A  and B, is positioned within the opening  44  in the base  24  of the housing  20 . Furthermore, the cooling element  400  is positioned substantially between the base  24  and the frame  102  of the carousel assembly  100 . Like the heating element  300 , the cooling element  400  is positioned radially outward of the driver and process fluid distribution system  200 . The cooling element  400  generally comprises an upper portion  402  with a cooling surface  404  that is placed in thermal contact with the workpiece W, an intermediate portion  406 , and a lower portion  410  that includes an actuator  412 , such as a bellows assembly, that moves the cooling element  400  for thermal processing of the workpiece W.  
      The upper portion  402  has a circular periphery  414  and a recessed annular ledge  416  positioned radially inward of the periphery  414 . In one embodiment the cooling surface  404  is located radially inward of the ledge  416 , while in another embodiment, the cooling surface  404  extends to the periphery  414  of the upper portion  402 . The cooling surface  404  includes an arrangement of vacuum channels  418  that are positioned about a central opening  420  of the cooling surface  404 . A passageway (not shown) extends transverse to the cooling surface  404  from the central opening  420  to an internal fitting (not shown). Vacuum air is supplied through the fitting and the passageway to the vacuum channels  418  wherein the vacuum air helps to maintain a vacuum seal engagement between the cooling element  400  and the workpiece W. A vacuum air delivery mechanism, including an external fitting  426 , extends through the intermediate and lower portions  406 ,  410  and is in fluid communication with the vacuum channels  418 . The vacuum air delivery mechanism is coupled to a vacuum source (not shown) that supplies the vacuum air used during annealing of the workpiece W.  
      Preferably, the upper portion  402  also includes a plurality of depressions  428  that extend radially inward from the periphery  414 . The depressions  428  are cooperatively positioned and dimensioned to receive an extent of the tabs  110  of the frame  102  of the carousel assembly  100  when the cooling element  400  is elevated by the bellows apparatus  412  to the use position and the cooling surface  404  thermally engages the workpiece W. The depressions  428  disengage the tabs  110  when the thermal processing is completed and the bellows apparatus  412  lowers the cooling element  400  to its original position. Alternatively, the depressions  428  are omitted and the workpiece W engages an extent of the cooling surface  404  when the cooling element  400  is elevated by the bellows apparatus  412 .  
      The upper portion  402  of the cooling element  400  further includes a cooling system  430  that comprises a plurality of internal channels  432 , at least one inlet port  434  and at least one outlet port  436 . The internal channels  432 , the inlet port  434  and outlet port  436  define a fluid passageway for the cooling medium utilize during operation of the cooling station  405 . The cooling medium used in the cooling system  430  and supplied to the channels  432  is a fluid such as water, glycol or a combination thereof. In operation, the cooling medium is supplied through the inlet ports  434  to the channels  432  and discharged by the outlet port  436 . Although shown in  FIG. 17D  as being positioned on one side of the upper portion  402 , the channels  432  are arrayed throughout the upper portion  402 . Thus, there is an innermost annular channel  432   a , an outermost annular channel  432   b  , and at least one intermediate annular channel  432   c . The precise number of channels  432  varies with the design parameters of the cooling element  400  and the cooling system  430 . An inner sealing ring  431  is positioned radially inward of the inner-most channel  432   a  and about a fastener  433  that secures the upper portion  402  to the intermediate portion  406 , and an outer sealing ring  435  is positioned radially outward of the outer-most channel  432   b . Preferably, the sealing rings  431 ,  433  are O-rings.  
      In one embodiment, the cooling system  430  includes an inlet manifold (not shown) that distributes the cooling media from the inlet ports  434  to the internal channels  432 . Similarly, the cooling system  430  includes a discharge manifold (not shown) that distributes cooling medium from the channels  432  to the discharge port  436 . In another embodiment, the inlet and outlet manifolds are omitted wherein the internal channels  432  are in fluid communication with each other to define a single, continuous fluid passageway from the inlet port  434 , through the internal channels  432  and to the outlet port  436 . In yet another embodiment, the internal channels  432  are annular channels arrayed in a concentric manner and are in fluid communication with inlet and discharge manifolds.  
      The intermediate portion  406  of the cooler element  300  is secured to the upper portion  402  by the fastener  426 . Although shown as having a solid, plate-like configuration, the intermediate portion  406  can include an insulated cavity. The intermediate portion  406  is secured to a top wall  438  of the lower portion  410  by fasteners  440  (See  FIG. 17D ).  
      The actuator or bellows assembly  412  is generally positioned in the lower portion  410  of the cooling element  400 . The bellows assembly  412  moves the upper and intermediate portions  402 ,  404 , including the cooling surface  404 , from the initial position towards the frame  102  of the carousel assembly  100  and to the use position. In the initial position and as shown in  FIG. 18B , there is a clearance C between the cooling surface  404  and the workpiece W. In the use position, the cooling element  400  is in thermal engagement with the workpiece W to enable heat transfer to the workpiece W. Preferably, in the use position, the cooling surface  404  is in direct contact with the non-device side of the workpiece W thereby eliminating the clearance C. Alternatively, in the use position, the cooling surface  404  is in close proximity to the non-device side of the workpiece W thereby significantly reducing the clearance C. When the bellows assembly  412  lowers the cooling element  400  from the use position to the initial position, the clearance C is present.  
      The bellows assembly  412  includes the top wall  438 , a bottom wall  444 , and a bellow  446 . In one embodiment, the bellow  446  has a cylindrical configuration and the bottom wall  444  has a central core  448  that is positioned within the bellow  446 . In another embodiment, the bellows assembly  412  includes a number of bellows  446  circumferentially spaced with respect to the bottom wall  436 . Referring to  FIG. 18B , at least one fastener  445  extends through the bottom wall  444  and the base  24  to secure the cooling element  400  to the carousel annealer  10  above the opening  44  in the base  24 .  
      As shown in  FIGS. 17B  and D, a mounting ring  449  depends from the bottom wall  444 . A cover  450  of the bellows assembly  412  is positioned within the central region of the ring  449 , wherein the cover  450  affixed to the bottom wall  444  by fasteners  451 . A bushing  452  is positioned within the cover  450  and is affixed to the bottom wall  444  by at least one fastener  454 . A sealing ring  456 , preferably an O-ring, is positioned within a cavity of the cover  450 . The bushing  452  has a central opening with a guide sleeve  458  that sliding engages an extent of a guide shaft  460 . A stop portion  460   a  extends transversely to a main body potion  460   b  of the shaft  460 . The shaft  460  is coupled to the top wall  438  at an upper portion  460   c  by at least one fastener  462 .  
      In operation of the bellow assembly  412 , the guide shaft  460  slides through the sleeve  458  and towards the cooling surface  404 . When the bellow assembly  412  moves the cooling element  400  to the use position, vacuum air is supplied for delivery through the central opening  420  in the cooling surface  404 . Similarly, when the cooling element  400  is raised to the use position, the cooling system  430  is activated to begin a cooling cycle for the workpiece W. Referring to  FIGS. 17B  and D, the bellows assembly  412  includes at least one inductive sensor  464  that extends through a side wall  453  of the cover  450  and that monitors the position of the cooling element  400 , including the shaft  460 . The sensor  464 , in connection with the control system  600 , prevents rotation of the carousel assembly  100  until the bellows assembly  412  returns the cooling element  400  to its initial position, as shown in  FIG. 18B . In operation, the sensor  464  and the control system ensure the timely rotation of the carousel assembly  100 , the delivery of vacuum air, and the activation of the cooling mechanism and the cooling cycle.  
      Referring to  FIGS. 19A , B, the carousel annealer  10  includes a loading station  505  where the workpiece W is inserted into the carousel assembly  100  to begin the thermal processing. The loading station  505  is a region of the carousel annealer  10  that is defined by a portion of the carousel assembly  100 , primarily the inner portion of the plate  102  including the tabs  110  that support the workpiece W, and the cover plate  126  of a cover assembly  120 ,  122 ,  124 . Preferably, the workpiece W is placed in the loading station  505  through the first opening  30 . Since the loading station  505  lacks a heating element  300  or a cooling element  400 , the supply lines  229 a-c are positioned near the loading station  505 . In another embodiment, the loading station  505  is omitted from the carousel annealer  10  whereby the workpieces W are loaded directly into the heating station  305 .  
      The loading, heating and cooling stations  305 ,  405 ,  505  are positioned radially outward of the driver and process fluid distribution system  200 . Although the loading, heating and cooling stations  305 ,  405 ,  505  are shown to be positioned approximately 120 degrees apart, the angular positioning can vary with the design parameters of the assembly  10  and the carousel  100 . In yet another embodiment, the carousel annealer  10  includes a loading station  505  and a distinct unloading station (not shown) wherein the thermally processed workpiece W is rotated to from the cooling station  405  for unloading. In this embodiment, the carousel annealer  10  is enlarged to accommodate the unloading station, as well as the loading, heating and cooling stations  305 ,  405 ,  505 .  
      As mentioned above, the carousel annealer  10  includes two inductive sensors  364 ,  464  that indicate and communicate the position of the heater and cooling elements  300 ,  400 . The sensors  364 ,  464  comprise a portion of a control system that monitors and controls a number of functions of the carousel annealer  10 , including the operation of the air cylinders  50 , the cover assemblies  120 ,  122 ,  124 , the process fluid assembly  205 , the driver assembly  215 , the bellows apparatus  312 ,  412 . Furthermore, the control system directs the operation and cycle times of the heating element  300  and the cooling element  400 . For example, the control system utilizes a closed-loop temperature sensor to ensure the proper operation of the heating element  300  at a process temperature. The feedback control can be a proportional integral control, a proportional integral derivative control or a multi-variable temperature control.  
      Referring to FIGS.  20 A,B, two annealing carousel annealers  10  are positioned in a stacked configuration within a stand  600 . The stand  600  includes a bottom plate  602 , a top plate  604  and a plurality of vertical legs  606 ,  608 ,  610 . A first carousel annealer  10   a is positioned above a second carousel annealer  10   b , wherein both carousel annealers  10   a, b  are supported by cross-members  612 . To ensure the loading and unloading of workpieces W, the first opening  30  and the second opening  32  of the carousel annealers  10   a, b  are positioned between legs  606 ,  608 ,  610 . Similarly, the side wall component  26  of the cover  22  of the carousel annealers  20   a, b  are positioned between legs  608 ,  610 . When the annealing carousel annealers  10   a, b  are stacked as shown in  FIGS. 20A , B, the throughput of processed workpieces W is increased while maintaining the same footprint as a single annealing carousel annealer  10 . A further advantage of the configuration shown in  FIGS. 20A , B is a reduction in the number of couplings needed to supply electrical power, process fluid and vacuum air.  
      In other embodiments, the carousel annealer  10  can have other configurations. For example, the cooling element  400  can utilize another medium to cool the workpiece, such as cold air. The cylinders  50  that actuate the cover assembly  120 ,  122 ,  124  can be replaced by an actuator that is non-pneumatic. The carousel annealer  10  can be configured to perform thermal processes other than annealing the workpiece W. For example, the heating element  300  can heat a microelectronic workpiece W to reflow solder on the workpiece W, cure or bake photoresist on the workpiece W, and/or perform other processes that benefit from and/or require an elevated temperature. The heating element  300  can heat the microelectronic workpiece W conductively by contacting the workpiece W directly, and/or conductively via an intermediate gas or liquid, and/or convectively via an intermediate gas or liquid, and/or radiatively. Similarly, the cooling element  300  can cool the workpiece W conductively by contacting the workpiece W directly, and/or conductively via an intermediate gas or liquid, and/or convectively via an intermediate gas or liquid, and/or radiatively.  
      The operation and thermal processing of a workpiece W in the carousel annealer  10  is explained with reference to above  FIGS. 7-19 . The method to thermally process microelectronic workpieces W in the carousel annealer  10  commences with the step of placing a workpiece W into the loading position P 0  at the loading station  505  of the carousel assembly  100  with the device side facing away from the base  24 . In the loading position P 0 , the workpiece W is positioned over a loading area  24   c  of the base  24  (see  FIG. 19B ). Referring to  FIG. 8 , in a preferred embodiment the frame  102  has three receivers  104 ,  106 ,  108 ; thus three workpieces W can be sequentially loaded into the carousel assembly  100  for thermal processing. To reach the loading position P 0 , the cover assembly  120 ,  122 ,  124  is moved from its closed position to the open position by engagement of the pedestal  54  of the air cylinder  50  with the cover control arm  128 . Specifically, the air cylinder  50  raises the shaft  52  in a substantially vertical direction which causes the pedestal  54  to engage and elevate the terminal end  138  of the control arm  128  thereby raising the cover plate  126 . When the pedestal  54  engages the terminal end  138 , the links  132  cause the control arm  128  to pivot about the mounting bracket  130  and thereby raise the cover plate  126  a distance sufficient to permit insertion of the workpiece W. After the workpiece W has been placed in the receiver  104 ,  106 ,  108 , the cover plate  126  is lowered to the closed position by the air cylinder  50 .  
      While the workpiece W is the loaded position P 0 , the process fluid distribution assembly  205  distributes a measured quantity of process air, such as nitrogen, through the passageway  231 , the cover assembly  120 ,  122 ,  124  and the distribution block  134  to the workpiece W to purge impurities. The cycle time for the process fluid is approximately 15-25 seconds. Once a sufficient quantity of process fluid is provided, the process fluid distribution assembly  205  can deliver a second process fluid, for example, 1 to 30 liters per minute of a non-oxidizing gas, e.g., nitrogen, argon, hydrogen or helium, through the passageway  231  to aid with the subsequent thermal processing of the workpiece W. When the process fluid is supplied at more than one flow rate, the carousel annealer  10  can include a mass flow controller and/or a multi-port manifold with a valve to selectively control the flow of fluid into the carousel annealer  10 . After a sufficient amount of process fluid is delivered by the process fluid distribution assembly  205  through the passageway  231  to the workpiece W in the loading station  505 , the driver assembly  215  rotates the carousel assembly  100  to the first position P 1 , wherein the workpiece W is positioned above the heating element  300  in the heating station  305 . Rotation of the carousel assembly  100  to move the workpiece W from the loaded position P 0  to the first position P 1  consumes approximately 1-3 seconds. As the carousel annealer  10  is configured in  FIGS. 7-19 , the carousel assembly  100  rotates in a counter-clockwise direction. However, the carousel annealer  10  can be configured to permit clockwise rotation of the carousel assembly  100 .  
      In one embodiment, to maintain a controlled processing environment, the cover plate  126  remains in the closed position as the workpiece W is rotated between the loaded position P 0 , the first position P 1  where the heating element  300  is engaged, and the second position P 2  where the cooling element  400  is engaged and the workpiece W is subsequently unloaded from the carousel annealer  10 . In another embodiment, the process fluid assembly  205  delivers a quantity of process fluid through the passageways  231  at each of the loaded position P 0 , the first position P 1  and the second position P 2 . In yet another embodiment, the process fluid assembly  205  selectively delivers a quantity of process fluid through the passageways  231  at the loaded position P 0 , the first position P 1  or the second position P 2 .  
      In the first position P 1 , the bellows assembly  312  raises or moves the heating element  300  from the base  24  of the housing  20  into the use position, wherein the heating element  300  is in thermal engagement with the workpiece W. The bellows assembly  312  takes approximately 1-3 seconds to raise and then subsequently lower the heater element  300 . Preferably, in the use position, the heating surface  304  is in direct contact with the non-device side of the workpiece W thereby eliminating the clearance C. Alternatively, in the use position, the heating surface  304  is in close proximity to the non-device side of the workpiece W thereby significantly reducing the clearance C. To maintain a vacuum seal engagement between the workpiece W and the heating surface  304  of the heater element  300 , a vacuum is applied via the vacuum channels  318 .  
      To thermally process components of the workpiece W, such as copper micro-structures, the heating element  300  operates at a selected process temperature for a specific period of time to define a heating cycle. Because the carousel annealer  10  has distinct heating and cooling elements  300 ,  400 , the heating element  300  does not need to be ramped-up or increased from an idle temperature to the process temperature. In contrast to conventional processing devices in which a heat source requires a temperature ramp-up, the heating element  300  can be maintained at or near the process temperature which increases the operating efficiency and life of the heating element  300 . Since the heating element  300  is in thermal engagement with the workpiece W, the process temperature of the heating element  300  and the process temperature of the workpiece W are substantially similar. For example, when the workpiece W includes a copper layer, the heater element  300 , with a process temperature ranging between 150 to 450 degrees Celsius, heats the workpiece W to a temperature in the range of 150 to 450 degrees Celsius for a cycle time ranging between 15 to 300 seconds. In one specific example, the workpiece W, including the copper layer therein, is heated to approximately 250 degrees Celsius for a cycle time of roughly 60 seconds. Accordingly, the copper layer can be annealed such that the grain structure of the layer changes (e.g., the size of the grains forming the layer can increase). In other embodiments, the workpiece W can be heated to a different temperature for another cycle time depending on the chemical composition of the workpiece W material to be thermally processed. The process temperature of the heater element  300  is controlled using a closed-loop temperature sensor feedback control incorporated into the carousel annealer control system  600 , such as a proportional integral control, a proportional integral derivative control or a multi-variable temperature control.  
      Upon expiration of the heating cycle time, the bellows assembly  312  lowers the heating element  300  to its original position with respect to the base  24 . The inductive sensor  364  monitors the position of the heating element  300  and communicates this information to the carousel annealer control system  600 . The sensor  364  and the control system  600  prevent further rotation of the carousel assembly  100  until the bellows assembly  312  has returned the heating element  300  to its original position. Therefore, once the sensor  364  detects that the heating element  300  has been lowered to its original position and the clearance C has been achieved, the driver assembly  215  rotates the carousel assembly  100  to the second position P 2 , wherein the workpiece W is positioned above the cooling element  400  in the heating station  405 . Rotation of the carousel assembly  100  to move the workpiece W from the first position P 1  to the second position P 2  consumes approximately 1-3 seconds. While a first workpiece W is in the first position P 1  and the heating element  300  is in the heating cycle, a second workpiece W can be placed in the loaded position P 0  in a manner consistent with that explained above.  
      In the second position P 2 , the bellows apparatus  412  raises or moves the cooling element  400  from the base  24  of the housing  20  into thermal engagement with the workpiece W. In the second position P 2 , the bellows apparatus  412  raises or moves the cooling element  400  from the base  24  of the housing  20  into the use position, wherein the cooling element  400  is in thermal engagement with the workpiece W. Preferably, in the use position, the cooling surface  404  is direct contact with the non-device side of the workpiece W thereby eliminating the clearance C. Alternatively, in the use position, the cooling surface  404  is in close proximity to the non-device side of the workpiece W thereby significantly reducing the clearance C. To maintain the thermal engagement between the workpiece W and the cooling surface  404  of the cooling element  400 , a vacuum is applied via the vacuum channels  418 .  
      The cooling system  430  of the cooling element  400  is then activated to cool the workpiece W to a selected temperature for a specific period of time, the cooling cycle time. For example, when the workpiece W includes a copper layer, the workpiece W can be cooled to a temperature below 70 degrees Celsius with a cycle time ranging between 15-25 seconds. During the cooling cycle, the cooling system  430  circulates the cooling medium through the fluid passageway defined by the internal annular channels  432  of the cooling element  400 . Compared to the heater element  300 , the cooling element  400  has a reduced cycle time. Because the process fluid cycle time and the cycle time of the cooling element  400  are less than the cycle time of the heating element  300 , there is sufficient time for an unprocessed workpiece W to be loaded into the loading station  505  and for a processed workpiece W to be unloaded from the cooling station  405 . Consequently, the throughput of the carousel annealer  10  is only dependent upon the cycle time of the heater element  300 .  
      Upon expiration of the cooling cycle, the bellows assembly  412  lowers the cooling element  400  to its original position with respect to the base  24 . The inductive sensor  464  monitors the position of the cooling element  400  and communicates this information to the carousel annealer control system  600 . The sensor  464  and the control system  600  prevent further rotation of the carousel assembly  100  until the bellows assembly  412  has returned the cooling element  400  to its original position. After the cooling cycle time is complete, the process fluid assembly  205  can replace the process gas with a flow of purge gas. In one embodiment, once the sensor  464  detects that the cooling element  400  has been lowered to its original position, the cover assembly  120 ,  122 ,  124  is moved from its closed position to the open position by engagement of the pedestal  54  of the air cylinder  50  with the cover control arm  128  as explained above. After the cover assembly  120 ,  122 ,  124  reaches the open position, the workpiece W is removed from the receiver  104 ,  106 ,  108 , preferably by a robot. In another embodiment, the driver assembly  215  rotates the carousel assembly  100  to the loaded position P 0 , wherein the cover assembly  120 ,  122 ,  124  is moved to the open position and the workpiece W is removed from the receiver  104 ,  106 , 108 . While a first workpiece W is in the second position P 2  and the cooling element  400  is in the cooling cycle, a second workpiece W is in the first position P 1  and a third workpiece W is in the loaded position P 0 .  
      As explained above, the carousel annealer  10  provides for the sequential thermal processing of a number of workpieces W N . In one embodiment, the frame  102  of the carousel annealer  10  has three receivers  104 ,  106 ,  108  and as a result, the carousel annealer  10  has the capacity to process three distinct workpieces W at one time. As an example of the processing sequence, the first cover assembly  120  is moved to the open position and a first workpiece W 1  is inserted in the first receiver  104  and placed in the loading position P 0  at the loading station  505 . There, the process fluid assembly  205  distributes process fluid through the passageway  231  to the workpiece W 1  to remove impurities. After a sufficient amount of process gas is delivered to the first workpiece W 1 , the driver assembly  215  rotates the carousel assembly  100  approximately 120 degrees to move the first workpiece W 1  from the loading position P 0  to the first position P 1 .  
      When the first workpiece W 1  reaches the first position P 1 , the second cover assembly  122  is moved to the open position and a second workpiece W 2  is inserted in the second receiver  106  and placed in the loading position P 0  at the loading station  505 . In the loading position P 0 , the process fluid assembly  205  distributes process fluid to the second workpiece W 2  to remove impurities and the second workpiece W 2  is readied for further processing. In the first position P 1 , the bellows assembly  312  raises the heating element  300  to the use position, wherein the heating element  300  is in thermal engagement with the first workpiece W 1 . To maintain the thermal engagement between the first workpiece W 1  and the heating surface  304  of the heater element  300 , a vacuum is applied via the vacuum channels  318 . The heating element  300  is then activated to the process temperature to thermally process components of the first workpiece W 1 . Upon expiration of the heating cycle time, the bellows assembly  312  lowers the heating element  300  to its original position with respect to the base  24 . Once the inductive sensor  364  detects that the heating element  300  has been lowered to its original position, the driver assembly  215  rotates the carousel assembly approximately 120 degrees which moves the first workpiece W 1  to the second position P 2  and the second workpiece W 2  to the first position P 1 .  
      When the first workpiece W 1  reaches the second position P 2  and the second workpiece W 2  reaches the first position P 1 , the third cover assembly  124  is moved to the open position and a third workpiece W 3  is inserted in the third receiver  108  and placed in the loading position P 0  at the loading station  505 . In the loading position P 0 , the process fluid assembly  205  distributes process fluid through the passageway  231  to the third workpiece W 3  to remove impurities and the third workpiece W 3  is readied for further processing. In the first position P 1 , the bellows assembly  312  raises or moves the heating element  300  to the heater use position, wherein the heating element  300  is in thermal engagement with the second workpiece W 2 . To maintain the thermal engagement between the second workpiece W 2  and the heating surface  304  of the heater element  300 , a vacuum is applied via the vacuum channels  318 . The heating element  300  is then activated to the process temperature to thermally process components of the first workpiece W 2 . Upon expiration of the heating cycle time, the bellows assembly  312  lowers the heating element  300  to its original position with respect to the base  24 . In the second position P 2 , the bellows apparatus  412  moves the cooling element  400  to the use position, wherein the cooling element  400  is in thermal engagement with the first workpiece W 1 . The cooling system  400  of the cooling element  400  is then activated to cool the first workpiece W 1  to the desired temperature. During the cooling cycle, the cooling system  400  circulates the cooling medium through the fluid passageway defined by the internal annular channels  432  of the cooling element  400 . Upon expiration of the cooling cycle, the bellows assembly  412  lowers the cooling element  400  to its original position with respect to the base  24 . The inductive sensor  464  monitors the position of the cooling element  400  and communicates this information to the carousel annealer control system  600 . After the inductive sensor  464  detects that the cooling element  400  has been lowered to its original position the first cover assembly  120  is moved from its closed position to the open position and the first workpiece W 1  is removed from the first receiver  104 . Next, the first cover assembly  120  is moved to the closed position and the driver assembly  215  rotates the carousel assembly approximately 120 degrees whereby the second workpiece W 2  is moved to the second position P 2  and the third workpiece W 3  is moved to the first position P 1 .  
      After the first workpiece W 1  is removed from the carousel annealer  10  and when the second workpiece W 2  reaches the second position P 2  and the third workpiece W 3  reaches the first position P 1 , the first cover assembly  120  is moved to the open position and a fourth workpiece W 4  is inserted in the first receiver  104  and placed in the loading position P 0  at the loading station  505 . In the loading position P 0 , the process fluid assembly  205  distributes process fluid through the passageway  231  to the fourth workpiece W 4  to remove impurities and the fourth workpiece W 4  is readied for further processing. In the first position P 1 , the bellows assembly  312  raises or moves the heating element  300  to the heater use position, wherein the heating element  300  is in thermal engagement with the third workpiece W 3 . To maintain the thermal engagement between the third workpiece W 3  and the heating surface  304  of the heater element  300 , a vacuum is applied via the vacuum channels  318 . The heating element  300  is then activated to the process temperature to thermally process components thereof. Upon expiration of the heating cycle, the bellows assembly  312  lowers the heating element  300  to its original position with respect to the base  24 . In the second position P 2 , the bellows apparatus  412  moves the cooling element  400  to the use position, wherein the cooling element  400  is in thermal engagement with the second workpiece W 2 . The cooling system  400  of the cooling element  400  is then activated to cool the second workpiece W 2  to the desired temperature. During the cooling cycle, the cooling system  400  circulates the cooling medium through the fluid passageway defined by the internal annular channels  432  of the cooling element  400 . Upon expiration of the cooling cycle, the bellows assembly  412  lowers the cooling element  400  to its original position with respect to the base  24 . The inductive sensor  464  monitors the position of the cooling element  400  and communicates this information to the carousel annealer control system  600 . After the inductive sensor  464  detects that the cooling element  400  has been lowered to its original position, the second cover assembly  122  is moved from its closed position to the open position and the second workpiece W 2  is removed from the second receiver  106 . Next, the second cover assembly  122  is moved to the closed position and the driver assembly  215  rotates the carousel assembly approximately 120 degrees whereby the third workpiece W 3  is moved to the second position P 2  and the fourth workpiece W 4  is moved to the first position P 1 .  
      After the second workpiece W 2  is removed from the carousel annealer  10  and when the third workpiece W 3  reaches the second position P 2  and the fourth workpiece W 4  reaches the first position P 1 , the second cover assembly  122  is moved to the open position and a fifth workpiece W 5  is inserted in the second receiver  106  and placed in the loading position P 0  at the loading station  505 . The thermal processing sequence of the third, fourth and fifth workpieces W 3 ,  4 ,  5  is consistent with that explained in the foregoing paragraphs. Consequently, the carousel annealer  10  provides for the sequential thermal processing of multiple workpieces, from the first workpiece W 1  to a number of workpieces W N .  
      From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use.