Abstract:
A method and apparatus for forming a substrate support is provided herein. In one embodiment, the substrate support is fabricated by a process that includes forming a groove in a body, disposing a heater element in the groove, and welding the groove to enclose the heater element, wherein the welding forces at least a portion of the body into intimate contact with the heater element. In another embodiment, a method of forming a substrate support is provided that includes forming a groove in a body, disposing a heater element in the groove and stir welding the groove closed to encase the heater element.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims benefit of U.S. Patent Application Ser. No. 60/727,930, filed Oct. 18, 2005, which is herein incorporated by reference in its entirety.  
         [0002]     This application is also related to U.S. patent application Ser. No. 10/965,601, filed Oct. 13, 2004 and to U.S. patent application Ser. No. 11/115,575, filed Apr. 26, 2005, which are herein incorporated by reference in there entireties. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     Embodiments of the invention generally provide a substrate support utilized in substrate processing and a method of fabricating the same.  
         [0005]     2. Description of the Related Art  
         [0006]     Liquid crystal displays or flat panels are commonly used for active matrix displays such as computer and television monitors. Generally, flat panels comprise two glass plates having a layer of liquid crystal material sandwiched therebetween. At least one of the glass plates includes at least one conductive film disposed thereon that is coupled to a power supply. Power supplied to the conductive film from the power supply changes the orientation of the crystal material, creating a pattern such as text or graphics that can be seen on the display. One fabrication process frequently used to produce flat panels is plasma enhanced chemical vapor deposition (PECVD).  
         [0007]     Plasma enhanced chemical vapor deposition is generally employed to deposit thin films on a substrate such as a silicon or quartz wafer, large area glass or polymer workpiece, and the like. Plasma enhanced chemical vapor deposition is generally accomplished by introducing a precursor gas into a vacuum chamber that contains the substrate. The precursor gas is typically directed through a distribution plate situated near the top of the chamber. The precursor gas in the chamber is energized (e.g., excited) into a plasma by applying RF power to the chamber from one or more RF sources coupled to the chamber. The excited gas reacts to form a layer of material on a surface of the substrate that is positioned on a temperature controlled substrate support. In applications where the substrate receives a layer of low temperature polysilicon, the substrate support may be heated in excess of 400 degrees Celsius. Volatile by-products produced during the reaction are pumped from the chamber through an exhaust system.  
         [0008]     Generally, the substrate support utilized to process flat panel displays are large, most often exceeding 550 mm×650 mm. The substrate supports for high temperature use are typically forged or welded, encapsulating one or more heater elements and thermocouples in an aluminum body. The substrate supports typically operate at elevated temperatures (i.e., in excess of 350 degrees Celsius and approaching 500 degrees Celsius). Due to these high operating temperatures, the heater elements encapsulated in the substrate supports are susceptible to failure due to local hot spots that may form if the heat is not properly carried away and distributed throughout the substrate support.  
         [0009]     Although substrate supports configured in this manner have demonstrated good processing performance, manufacturing such supports has proven difficult and expensive. Moreover, as the cost of materials and manufacturing the substrate support is great, failure of the substrate support is highly undesirable. Additionally, if the substrate support fails during processing, a substrate supported thereon may be damaged. As this may occur after a substantial number of processing steps have been preformed thereon, the resulting loss of the in-process substrate may be very expensive. Furthermore, replacing a damaged support in the process chamber creates a costly loss of substrate throughput while the process chamber is idled during replacement or repair of the substrate support. Moreover, as the size of the next generation substrate supports are increased to accommodate substrates in excess of 2 square meters at operating temperatures approaching 500 degrees Celsius, the aforementioned problems become increasingly more important to resolve.  
         [0010]     Therefore, there is a need for an improved substrate support.  
       SUMMARY OF THE INVENTION  
       [0011]     A method and apparatus for forming a substrate support is provided herein. In one embodiment, the substrate support is fabricated by a process that includes forming a groove in a body, disposing a heater element in the groove, and welding the groove to enclose the heater element, wherein the welding forces at least a portion of the body into intimate contact with the, heater, element. In another embodiment, a method of forming a substrate support is provided that includes forming a groove in a body, disposing a heater element in the groove and stir welding the groove closed to encase the heater element. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0013]      FIG. 1  is a schematic sectional view of one embodiment of a processing chamber having a substrate support of the present invention;  
         [0014]      FIG. 2  is a partial cross-sectional view of one embodiment of the substrate support assembly of  FIG. 1 ;  
         [0015]      FIGS. 3 and 5 - 7  are partial cross-sectional and bottom views of a substrate support assembly illustrating different stages of fabrication;  
         [0016]      FIG. 4  is an elevation of one embodiment of a tool suitable for use in the fabrication sequence described with reference to the  FIGS. 3 and 5 - 7 ;  
         [0017]      FIGS. 8-9  are partial cross-sectional and bottom views of another substrate support assembly illustrating different stages of fabrication;  
         [0018]      FIGS. 10-12  are bottom and partial sectional views of another substrate support in different stages of fabrication;  
         [0019]      FIG. 13  is a top plan view of another embodiment of a substrate support assembly;  
         [0020]      FIG. 14  is a partial cross-sectional view of another embodiment of the substrate support assembly;  
         [0021]      FIG. 15  is a partial cross-sectional view of the substrate support assembly of  FIG. 14  prior to welding;  
         [0022]      FIG. 16  is a partial cross-sectional view of the stem to body interface of the substrate support assembly of  FIG. 14 ;  
         [0023]      FIG. 17  is a partial cross-sectional view of another embodiment of the substrate support assembly;  
         [0024]      FIG. 18  is a partial cross-sectional view of the substrate support assembly of  FIG. 17  prior to welding;  
         [0025]      FIG. 19  is a is a partial cross-sectional view of another embodiment of the substrate support assembly; and  
         [0026]      FIG. 20  is a schematic sectional view of another embodiment of a processing chamber having heating and/or cooling features embedded using the method of present invention. 
     
    
       [0027]     To facilitate understanding, identical reference numerals have been used, wherever possible, to designate identical elements that are common to the figures. It is contemplated that features and elements of one embodiment may be beneficially incorporated in other embodiments without further recitation.  
       DETAILED DESCRIPTION  
       [0028]     The invention generally provides a heated substrate support and methods of fabricating the same. The invention is illustratively described below in reference to a PECVD system, such as a PECVD system available from AKT, a division of Applied Materials, Inc., located in Santa Clara, Calif. However, it should be understood that the invention has utility in other system configurations such as physical vapor deposition systems, ion implant systems, etch systems, other chemical vapor deposition systems and other systems in which use of a heated substrate support is desired.  
         [0029]      FIG. 1  is a cross sectional view of one embodiment of a plasma enhanced chemical vapor deposition system  100 . The system  100  generally includes a chamber body  102  coupled to a gas source  104 . The chamber body  102  has walls  106 , a bottom  108 , and a lid assembly  110  that define a chamber volume  112 . The chamber volume  112  is typically accessed through a port (not shown) in the walls  106  that facilitates movement of the substrate  140  into and out of the chamber body  102 . The walls  106  and bottom  108  are typically fabricated from a unitary block of aluminum or other material compatible for processing. The lid assembly  110  contains a pumping plenum  114  that couples the chamber volume  112  to an exhaust port (that includes various pumping components, not shown).  
         [0030]     The lid assembly  110  is supported by the walls  106  and can be removed to service the chamber body  102 . The lid assembly  110  is generally comprised of aluminum. A distribution plate  118  is coupled to an interior side  120  of the lid assembly  110 . The distribution plate  118  is typically fabricated from aluminum. The center section includes a perforated area through which process and other gases supplied from the gas source  104  are delivered to the chamber volume  112 . The perforated area of the distribution plate  118  is configured to provide uniform distribution of gases passing through the distribution plate  118  into the chamber body  102 .  
         [0031]     A heated substrate support assembly  138  is centrally disposed within the chamber body  102 . The support assembly  138  supports a substrate  140  during processing. The substrate may be a silicon, glass, plastic or other workpiece, for example, those substrates suitable for manufacturing flat panel displays, OLEDs, solar panels and the like. In one embodiment, the substrate support assembly  138  comprises an aluminum body  124  that encapsulates at least one embedded heater element  132  and a thermocouple  190 . The body  124  may optionally be coated or anodized. Alteratively, the body  124  may be made from other weldable materials compatible with the processing environment, and may also be comprised one or more sections. It is recognized that encapsulating the heater element  132  in a one-piece body  124  will provide advantages in ease of fabrication, enhance temperature uniformity and heater performance.  
         [0032]     The heater element  132 , such as an electrode disposed in the support assembly  138 , is coupled to a power source  130  and controllably heats the support assembly  138  and substrate  140  positioned thereon to a predetermined temperature. Typically, the heater element  132  maintains the substrate  140  at a uniform temperature of from about 150 to at least about 460 degrees Celsius. Although one heater element  132  is shown, it is contemplated that multiple heater elements may be utilized and independently controlled to provide zones of temperature control. It is also contemplated that the heater element  132  may be a fluid conduit adapted to flow a heat transfer fluid therethrough, among other temperature control devices.  
         [0033]     Generally, the support assembly  138  has a lower surface  134  and an upper surface  136 . The upper surface  136  is configured to support the substrate during processing. In one embodiment, the upper surface  136  is configured to support a substrate greater than or equal to about 550 by about 650 millimeters. In one embodiment, the upper surface  136  has a plan area greater than or equal to about 0.35 square meters for supporting substrates having a size greater than or equal to about 550 by 650 millimeters. In one embodiment, the upper surface  136  has a plan area of greater than or equal to about 2.7 square meters (for supporting substrates having a size greater than or equal to about 1500 by 1800 millimeters). The upper surface  136  may generally have any shape or configuration. In one embodiment, the upper surface  136  has a substantially polygonal shape. In one embodiment, the upper support surface is a quadrilateral.  
         [0034]     The lower surface  134  has a stem cover  144  coupled thereto. The stem cover  144  generally is an aluminum ring sealably coupled to the support assembly  138  that provides a mounting surface for the attachment of a stem  142  thereto. The stem  142  is sealingly coupled the stem cover  144  at an upper end and is coupled at a lower end to a lift system (not shown) that moves the support assembly  138  between an elevated position (as shown) and a lowered position. A bellows  146  provides a vacuum seal between the chamber volume  112  and the atmosphere outside the chamber body  102  while facilitating the movement of the support assembly  138 . The stem  142  additionally provides a conduit for electrical and thermocouple leads between the support assembly  138  and other components of the system  100 . To provide a pressure barrier between the interior passages of the stem  142  and the chamber volume  112  of the chamber body  102 , the stem  142  is continuously welded to the stem cover  144 . Likewise, the stem cover  144  is sealed to the lower surface  134  of the body  124  by a continuous weld  170 .  
         [0035]     The support assembly  138  has a plurality of holes  128  disposed therethrough that accept a plurality of lift pins  150 . The lift pins  150  are typically comprised of ceramic or anodized aluminum. Generally, the lift pins  150  have first ends  160  that are substantially flush, with or slightly recessed from an lower surface  134  of the support assembly  138  when the lift pins  150  are in a normal position (i.e., retracted relative to the support assembly  138 ). The first ends  160  are generally flared to prevent the lift pins  150  from falling through the holes  128 . A second end  164  of the lift pins  150  extends beyond the lower side  126  of the support assembly  138 . The lift pins  150  may be displaced relative to the support assembly  138  by a lift plate  154  to project from the support surface  134 , thereby placing the substrate in a spaced-apart relation to the support assembly  138 .  
         [0036]     The support assembly  138  generally is grounded such that RF power supplied by a power source  122  to the distribution plate  118  (or other electrode positioned within or near the lid assembly of the chamber) may excite the gases disposed in the chamber volume  112  between the support assembly  138  and the distribution plate  118 . The RF power from the power source  122  is generally selected commensurate with the size of the substrate to drive the chemical vapor deposition process.  
         [0037]     The support assembly  138  additionally supports a circumscribing shadow frame  148 . Generally, the shadow frame  148  prevents deposition at the edge of the substrate  140  and support assembly  138  so that the substrate does not stick to the support assembly  138 .  
         [0038]      FIG. 2  depicts a partial cross-sectional view of the heater element  132  disposed in the body  124  of the substrate support assembly  138 . The heater element  132  generally includes a plurality of conductive elements  224  encased in a dielectric  222  and covered with a protective sheath  220 . The heater element  132  may optionally include a cladding which surrounds the sheath  220 . The cladding forms an integral bond with the sheath  220 , having substantially no air pockets trapped between the cladding and the sheath  220 . In one embodiment, the heater element  132  may be clad by tightly wrapping a conformable sheet of the cladding around the sheath  220 .  
         [0039]     Generally, the cladding has good thermal conductivity and is thick enough to be a heat sink at high heating rates to substantially prevent hot spots on the heater element  132  during operation. As such, the cladding generally may comprise any material with high thermal conductivity such that the cladding is a sink for the heat produced by the conductive elements  224  during operation. The cladding is also generally softer, or more malleable, than the body  124  of the substrate support assembly  138 . In one embodiment, the cladding may be made from a high purity, super plastic aluminum material, such as aluminum  1100  up to about aluminum 3000-100 series. In another embodiment, the cladding may be made from any 1XXX series of materials that easily accepts cold or hot working, where X is an integer. The cladding may be fully annealed. In one embodiment, the cladding is formed from aluminum 1100-0. In another embodiment, the cladding is formed from aluminum 3004.  
         [0040]     The heater element  132  is encased in the body  124  using a process that urges the material of the body  124  into intimate contact with the heater element  132 . In the embodiment depicted in  FIG. 2 , the heater element  132  is encased in the body  124  using a friction stir welding process.  
         [0041]     As shown in  FIG. 2 , a weld effected region  204  is disposed above the heater element  132 . A non-effected region  202  is laterally offset from the weld effected region  204 , and also is in contact with a portion of the heater element  132 . During the welding process that encases the heater element  132  in the body  124 , the weld effected region  204  becomes subject to plastic deformation, and under the pressure of the weld, is forced toward and makes intimate contact with the heater element  132 . The extruded weld effected region  204  places the body  124  and heater element  132  in good thermal contact, for example, greater than about 75 percent.  
         [0042]      FIGS. 3 and 5 - 7  depict partial sectional and top view of the body  124  illustrating one embodiment of a fabrication sequence for embedding the heater  132 .  FIG. 4  depicts one embodiment of a tool  400  suitable for stir welding the body  124  during the fabrication sequence of illustrated by  FIGS. 3 and 5 - 7 .  
         [0043]     Referring first to  FIG. 3 , a groove  302  is formed in the bottom surface  134  of the substrate support assembly  138  to accept the heater element  132 . A depth  316  of the groove  302  may be selected to position the heater element  132  at a predefined location in the body  124 . In one embodiment, the depth  316  is equal to or slightly greater than half the thickness of the body  124 .  
         [0044]     A width  312  of the groove  302  may be selected to create a press-fit with the heater element  132  and the walls  380  of the groove on insertion into the groove. Alternatively, the width  312  may be selected to provide clearance between the walls of the groove  302  (walls  382  are shown in phantom) and the heater element  132 , thereby allowing the heater element  132  to be freely disposed on a bottom  320  of the groove  302 .  
         [0045]     The walls of the groove  302  may be substantially straight and parallel, or optionally formed at a slight angle or taper, such that the bottom  320  of the groove  302  is slightly narrower than the top portion of the groove  302  defined at the bottom surface  134 . The angle of taper of the groove  302  is generally less than 3 degrees, although larger taper angles are also contemplated. In one embodiment, the sidewalls of the groove  302  are tapered such that the bottom of the groove has approximately the same width as the diameter of the heater element  132 . Thus, the heater element  132  may be forced into and become engaged with the groove  302  to prevent the heater element  132  from “popping” out of the groove prior to installation of the cap  304 .  
         [0046]     The bottom  320  of the groove  302  may be radiused to conform with the shape of the heater element  132 . Alternatively, or in combination, the bottom  320  of the groove  302  may be roughened, or textured.  
         [0047]     The cap  304  is disposed in the groove  302  and covers the heater element  132 . The cap  304  has an outer surface  306  that is disposed substantially flush with the lower surface  134  of the substrate support assembly  138 . The cap  304  is may be press fit, or have a small clearance with the walls of the groove  302 . The cap  304  is formed from a material suitable for welding to the body  124 , and in one embodiment, is aluminum.  
         [0048]     Referring now to the elevation of the tool  400  depicted in  FIG. 4 , the tool  400  has a disc-shaped body  404  and a probe  406  extending from one side and a shaft  408  extending from the opposite side of the tool  400 . The shaft  408  facilitates coupling the tool  400  to an actuator (not shown) that controls the rotation, down-force and lateral motion to the tool  400 . The tool  400  is fabricated from a wear resistance material suitable for stir welding the body  124  and cap  304 .  
         [0049]     The body  404  may have a diameter  410  such that an outer edge  420  of the body  404  is equal to or greater than about the width  312  of the groove  302 . A shoulder  402  of the body  404  has sufficient surface area to heat the body  124  and cap  304  of the substrate support assembly  138  when rotated thereagainst during the stir welding process.  
         [0050]     The probe  406  may have a diameter  414  that is equal to or greater than about half the width  312  of the groove  302 . It is also contemplated that the diameter  414  may be less than about half the width  312  of the groove  302 . The probe  406  has a length  412  that is slightly less than a depth  314  of the cap  304 , as seen in the side-by-side arrangement of  FIGS. 3 and 4 . The length  412  of the probe  406  is selected to cause the plasticized portions of the body  124  and/or cap  304 , created during welding, to be extruded or otherwise forced towards the heater element  132 , thereby filling the pre-weld voids  310  present between the heater element  132  and cap  304 , and thereby creating an intimate heat transfer contact surface between the heater element  132  and the body  124 .  
         [0051]      FIGS. 5 and 6  depict the path of the tool  400  over the body  124  during the welding process. Referring first to  FIG. 5 , the tool  400  is disposed against the body  124  such that the shoulder  402  of the tool  400  is in contact with the bottom surface  134  of the body  124 . The probe  406  is penetrated into the groove  302 . To accommodate entry and exit of the probe  406  into the groove  302 , the cap  304  may end short of the lateral end of groove  302 , which will become apparent in the discussion of  FIGS. 10-11  below.  
         [0052]     As the tool  400  spins and advances along a first interface  502  between the body  124  and cap  304 , the advancing probe  406  plasticizes adjacent regions of the body  124  and cap  304 , forming a solid phase bond  506  between the body  124  and cap  304  along the trailing edge of the probe  406 . The solid phase bond  506  created by this stir welding technique is defined by a first outer weld line  510  defined between the body  124  and the solid phase bond  506  and an interim weld line  512  defined between the cap  304  and the solid phase bond  506  by the outer edge  420  of the tool  400 . A second interface  504  between the body  124  and cap  304  remains unwelded during the first pass of the tool  400 .  
         [0053]     Referring now to  FIG. 6 , the second interface  504  between the body  124  and cap  304  is welded in a manner similar to the welding of the first interface  502 . The probe  406  is rotated and advanced along the second interface  504 . The probe  406  plasticizes the adjacent regions of the cap  304  and the solid phase bond  506  created during the first pass of the tool  400  described with reference to  FIG. 5 . The solid phase bond  506  is expanded along the trailing edge of the probe  406  such that the residual portion of the cap  304  remaining after the first pass is consumed during the welding of the second interface  504 , becoming an integral part of the body  124 . The expanded solid phase bond  506  fuses the body  124  on opposing sides of the groove  302 , thereby encapsulating the heater element  132  in the body  124 . The solid phase bond  506  created by the stir welding technique is now defined by the first outer weld line  510  defined between the body  124  and the solid phase bond  506  and a second outer weld line defined between the body  124  and the solid phase bond  506  by the outer edge  420  of the tool  400 .  
         [0054]     During the passes of the tool  400  along the interfaces  502 ,  504  between the body  124  and cap  304 , the plasticized material from the body  124  and/or the cap  304  is retained substantially in the groove  302  by the shoulder  420  of the tool  400 . The plasticized material is forced towards the heater element  132 , thereby substantially filling the voids  310  present prior to welding, as shown in  FIG. 7 . A portion of the voids  310  may remain unfilled after processing, leaving an air pocket  704  proximate the heater element  132 . The air pocket  704  is usually small or non-existent. In one embodiment, at least 25 percent of the circumference of the heater element  124  is in contact with the body  124 . In other embodiment, at least 50 percent of the circumference of the heater element  124  is in contact with the body  124 . In other embodiment, at least 25 percent of the circumference of the heater element  124  is in contact with the body  124 . In still another embodiment, the circumference of the heater element  124  is completely contacting the body  124 .  
         [0055]     The tool  400  may form a shallow trench in the body  124  during the welding operations. To elimination the trench, a portion  702  of the lower surface  134  of the body  124  may be machined (i.e., removed) after welding to return the lower surface  134  to a substantially planar condition. The substrate support assembly  138  may also be machined on the upper side  136  to balance the heat distribution from the embedded heater element  132 .  
         [0056]      FIG. 8  is a partial sectional view of another embodiment of tool  800  for encapsulating the heater element  132  in the body  124  of the substrate support assembly  138 . Tool  800  is substantially similar to the tool  400  described above, except that a probe  802  extending from a body  810  of the tool  800  has a diameter  812  slightly greater than the width  312  of the groove  302 . The wider probe  802  allows the probe  802  to integrate the material of the cap  304  into the body  124  using a single pass of the probe  800 , as shown in  FIG. 9 . The cap  304  is consumed and incorporated into the body  124  as a continuous solid phase bond  506  defined by the weld lines  902 ,  904  separating the non-effected regions  202  from the weld effected regions  204  of the body  124 .  
         [0057]      FIGS. 10-11  are bottom views of the body  124 . The groove  302  may be formed in the bottom surface  134  of the body  124  in a predefined configuration arranged to provide a desired heat distribution. Ends  1002 ,  1004  of the groove  302  are located inside the location of the weld  170  (shown in phantom) used to secure the cover plate to the  144  to the body  124  after installation of the heater element  124 . In embodiments where multiple heater elements  132  are utilized, more than one groove  302  may be formed in the body  124  with ends thereof located inside the weld  170 , as described above.  
         [0058]     Holes  1102 ,  1104  are formed by the welding process at the ends of  1002 ,  1004  of the groove  302 . Referring additionally to  FIG. 12 , the holes  1102 ,  1104 , which permit engagement of the probe with the support assembly  138 , facilitate the routing of heater leads  1204  into a conduit  1204  defined through the stem  142 . As the holes  1102 ,  1104  are positioned inside the weld  170 , the solid phase bond  506  covering the portion of the heater element  132  outside of the cover plate  144  provides a pressure barrier between the chamber volume  112  of the chamber body  102  and the environment shared by the heater element  132  and conduit  1204 .  
         [0059]     It is contemplated that the groove  302  may be formed in the upper surface  136  of the support assembly, wherein the through holes  1102 ,  1104  are provided to allow access of the leads  1204  to the conduit  1202  defined by the stem  142 . In such an embodiment, a plug is conventionally welded to seal the portion of the holes  1102 ,  1104  provided on the upper surface  136  to accommodate the probe of the stir welding tool.  
         [0060]      FIG. 13  is a top plan view of one embodiment of a substrate support assembly  1300  having multiple, illustratively shown heater elements as two heater elements  1302 ,  1304  in broken lines.  
         [0061]     A body  1310  of the support assembly  1300  includes an upper surface  132  that is divided into a plurality of thermal control zones, shown illustratively as two control zones  1314 ,  136 .A first outer zone heater element  1318  is embedded within a periphery of the first zone  1314  of the body  1310 . A first inner zone heater element  1320  is embedded within an area bounded by the first outer zone heater element  1318 . A second outer zone heater element  1322  is embedded within a periphery of the second zone  1316 . A second inner zone heater element  1324  is embedded within an area bounded by the second outer zone heater element  1322 .  
         [0062]     A first outer thermocouple  1326  is embedded within the body  1310  and between the first outer zone heater element  1318  and the first inner zone heater element  1320  for controlling temperature of the first zone  1314 . In addition, a second outer thermocouple is embedded within the body  1310  and extends between the second outer zone heater element  1322  and the second inner zone heater element  1324  for controlling temperature of the second zone  1316 .  
         [0063]     Leads for the heater elements  1318 ,  1320 ,  1322 ,  1324  and the thermocouples  1326 ,  1324  may be routed into the shaft  142  of the substrate support assembly  1300  as illustrated in  FIG. 12 . Additionally, the temperature of the heater elements  1318 ,  1320 ,  1322 ,  1324  may be individually controlled, such that the temperature profile of the body in the substrate position thereon may be regulated.  
         [0064]      FIG. 14  is a partial sectional view another embodiment of a substrate support assembly  1400  having at least one cooling passage  1402 . The substrate support assembly  1400  is generally similar to the substrate support assemblies described above, with a heater element  132  stir-welded in a body  124  of the substrate support assembly  1400 .  
         [0065]     The cooling passage  1402  is generally formed in the body  124  between the heater element  132  and the lower-surface  134  of the body  124 . The cooling passage  1402  is coupled to a coolant fluid source (not shown) which provides a heat transfer fluid (such as water, among others) that is circulated through the cooling passage  1402  to assist in regulating the temperature of the support assembly  1400 .  
         [0066]     In one embodiment, the heat transfer fluid is circulated in a tube  1412  disposed in the cooling passage  1402 . Alternatively, the heat transfer fluid may be circulated directly in contact with the body  124  defining the cooling passage  1402 . The cooling passage  1402  may be larger than the tube  1412  such that the tube  1412  makes intermittent contact with the body  124  (as shown in  FIG. 16 ). Alternatively, the tube  1412  may be tightly disposed in the passage  1402  or compressed against the body  124 . The tube  1412  may be fabricated from a material having good heat conduction, suitable for use at operating temperatures of the support assembly  132 , and compatible with the heat transfer fluid. One example of a suitable material for the tube  1412  is stainless steel.  
         [0067]     In the embodiment depicted in  FIG. 14 , the body  124  includes a non-effected region  1410  and a weld-effected region  1404  generated while embedding the heater element  132 . The cooling passage  1402  may be positioned between the heater element  132  and the upper surface  134  of the body  124 , and in the embodiment depicted in  FIG. 14 , the cooling passage  1402  and tube  1412  are disposed in the weld-effected region  1404 . The cooling passage  1402  may alternatively be offset from the weld-effected region  1404 , as shown in  FIG. 19 .  
         [0068]     Referring additionally to  FIG. 15 , a lower boundary of the cooling passage  1402  is formed by a channel  1502  formed in the weld-effected region. An upper boundary of the cooling passage  1402  is formed by a cap plate  1408  that is positioned in the channel  1502  and welded to the upper surface  134 . In one embodiment, the channel  1502  includes a step  1504  that supports the cap plate  1408  in a predefined position to set the sectional area of the cooling passage  1402 . The cap plate  1408  is continuously welded to seal the channel  1502 , for example, by electron beam or other weld methodology suitable for forming a continuous seal.  
         [0069]     In the embodiment depicted in  FIG. 15 , a stir welding tool  1500  is utilized to stir weld the cap plate  1408  to the body  124 . The tool  1500  is configured to generate a small weld-effected zone  1406  that is offset from the channel  1502  to minimize the possibility of material, extruded during the welding process, from entering the passage  1402 .  
         [0070]      FIG. 16  is a partial sectional view of the support assembly  1400  illustrating an inlet port  1600  of the cooling passage  1402 . The port  1600  is positioned inside the weld  170 , thereby allowing the tube  1412  (or conduit coupled thereto) to be routed through the stem  142  to a cooling fluid source (not shown) while maintaining isolation from the environment inside the processing chamber. The port  1600  is generally formed at the exit location of the tool  1500 . The port  1600  may be formed in the tool exit hole, or the tool exit hole may be sealingly plugged before forming the port  1600 .  
         [0071]      FIG. 17  is a partial sectional view another embodiment of a substrate support assembly  1700  having at least two cooling passages  1702 ,  1704 . The substrate support assembly  1700  is generally similar to the substrate support assemblies described above, with a heater element  132  stir-welded in a body  124  of the substrate support assembly  1700 . In the embodiment depicted in  FIG. 17 , a respective tube  1412  is deposed in each cooling passage  1702 ,  1704 .  
         [0072]     The cooling passages  1702 ,  1704  are generally formed in the body  124  between the heater element  132  and the lower surface  134  of the body  124 . The tubes  1412  disposed in the cooling passages  1702 ,  1704  are coupled to a coolant fluid source (not shown) which provides a heat transfer fluid that is circulated through the passages. The tubes  1412  in the cooling passages  1702 ,  1704  may be coupled to the coolant fluid source in a manner that provides the fluid of the same temperature through the passages, or the temperature of the fluid in each tube  1412  disposed in the cooling passages  1702 ,  1704  may be independently controlled. The cooling passages  1702 ,  1704  may arranged in an offset orientation, or may be routed thought different portions of the body  124  such that cooling may be independently controlled in different lateral zones. For example, the first passage  1702  may be predominantly routed and/or located in the central region of the body  124  while the second passage  1704  may be predominantly routed and/or located in the outer regions/perimeter of the body  124  (i.e., the first passage  1702  is disposed inward of the second passage  1704 ). The flow direction of fluid through the cooling passages  1702 ,  1704  may be in the same or opposing directions.  
         [0073]     In the embodiment depicted in  FIG. 17 , the body  124  includes a non-effected region  1710  and a weld-effected region  1708  generated while embedding the heater element  132 . The cooling passages  1702 ,  1704  and tubes  1412  may be positioned between the heater element  132  and the upper surface  134  of the body  124 , and in the embodiment depicted in  FIG. 17 , the cooling passages  1702 ,  1704  are disposed at least partially in the weld-effected region  1708 . An upper boundary of each of the cooling passages  1702 ,  1704  is formed by at least one cap plate  1718 . The cooling passages  1702 ,  1704  may be bounded by a single or separate cap plates  1718 .  
         [0074]     Referring additionally to  FIG. 18 , a lower boundary of the cooling passages  1702 ,  1704  are formed by channels  1802 ,  1804  formed in the weld-effected region  1708 . The cap plates  1718  are positioned in the channels  1802 ,  1804  and are welded to the upper surface  134  as described above. In one embodiment, each channel  1802 ,  1804  includes a step  1806  that supports the cap plates  1718  in a predefined position.  
         [0075]     In the embodiment depicted in  FIG. 18 , a stir welding tool  1800  is utilized to stir weld the cap plates  1718  to the body  124 . The tool  1800  is configured to generate a small weld-effected zone  1720  that is offset from the channels  1802   1804  to minimize the possibility of material, extruded during the welding process, from entering the passages  1702 ,  1704 . The ports (not shown) of the passages  1702 ,  1704  are positioned inside the weld  170 , as described with reference to  FIG. 16 .  
         [0076]     It is additionally contemplated that heating and/or cooling features may be embedded using the stir welding techniques described above in other components of a processing system. For example, in the embodiment of the system  100  depicted in  FIG. 20 , at least one of a heater element  132  and/or a cooling passage  1402  is embedded in a component thereof, such as a chamber body  102  and/or lid  110 , and/or other component. A tube  1412  may be disposed in the passage  1402 . A weld effected region  2002  effectively embeds the heater element  132  and/or seals cooling passage  1402  as discussed above.  
         [0077]     Thus, a substrate support assembly has been provided that has an embedded heater element that is in intimate contact with the base material comprising the body of the substrate support. Advantageously, the process provides a pressure barrier while extruding the base material into contact with the heater, thereby filling voids that contribute to non-uniformity and heater burn-out. Moreover, the heater element embedding process allows for the substrate support assembly to be fabricated from a single plate (e.g., body) which is advantageous over multi-plate susceptors/heaters for ease of fabrication, heater location control and low cost. Moreover, the embedding technique may be advantageously utilized to efficiently embed heater and/or cooling elements in other portions of a processing system.  
         [0078]     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.