Abstract:
A method of making an electrostatic chuck comprising positioning a plate into a channel in a body to form a plenum and inserting a dielectric component into an opening in the plate, where the dielectric component defines a portion of a passage from the plenum. Thereafter, depositing a dielectric layer covering at least a portion of the body and at least a portion of the plate to form a support surface. The dielectric layer is polished to a specified thickness. In one embodiment, the polishing process forms an opening through the dielectric layer to enable the dielectric component to define a passage between the support surface and the plenum. In another embodiment, at least a portion of the dielectric layer is porous proximate the dielectric component such that the porous dielectric layer and the dielectric component form a passage between the support surface and the plenum. In a further embodiment, a hole is formed through the dielectric layer and the hole in the dielectric layer and the dielectric component form a passage between the support surface and the plenum.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application contains subject matter that is related to U.S. patent application Ser. No. ______, filed simultaneously herewith, entitled METHOD FOR REFURBISHING AN ELECTROSTATIC CHUCK WITH REDUCED PLASMA PENETRATION AND ARCING (Attorney Docket No. 11735US02/AGS/IBSS), and application Ser. No. ______, filed simultaneously herewith, entitled METHOD AND APPARATUS FOR PROVIDING AN ELECTROSTATIC CHUCK WITH REDUCED PLASMA PENETRATION AND ARCING, (Attorney Docket No. 11736/AGS/IBSS). The aforementioned related patent applications are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to equipment for performing semiconductor device fabrication, and more particularly, to an electrostatic chuck for supporting a semiconductor wafer during processing. 
         [0004]    2. Description of the Related Art 
         [0005]    Electrostatic chucks are widely used for providing support to substrates (also referred to herein as semiconductor wafers or wafers) within semiconductor processing equipment such as a plasma processing chamber. An electrostatic chuck generally holds a substrate in a stationary position during processing of the substrate, i.e., during material deposition or etching. Electrostatic chucks utilize capacitive and Johnsen-Rahbeck attractive forces for holding the substrate in position. 
         [0006]    One type of electrostatic chuck includes a body and a fluid distribution element covered with a layer of a dielectric material thereby forming a support surface. The body is generally conductive such that the body forms an electrode of the electrostatic chuck. A substrate is placed onto the support surface. The fluid distribution element includes a plenum that carries the fluid multiple passages formed in the support surface of the electrostatic chuck for distributing a heat transfer fluid such as a gas between the support surface of the chuck and the backside of the substrate. Generally, the gas fills the interstitial area between the electrostatic chuck and the substrate, thus enhancing the rate and uniformity of heat transfer between electrostatic chuck and the substrate. 
         [0007]    In plasma processing chambers, the electrostatic chuck is subjected to high power radio frequency (RF) fields and high density plasmas in the vicinity of the substrate. In such plasma processing chambers, it is possible to have the gas breakdown due to high electric field generation in the gas passages. The operation and service life of the electrostatic chuck is adversely affected by plasma formation in the gas passages. Such plasma may damage the substrate, the electrostatic chuck or both. Furthermore, plasma formation in a gas passage can lead to arcing that forms particulate contaminants in the chamber. 
         [0008]    There exist various techniques for reducing the plasma formation in gas passages. One technique includes inserting a porous dielectric plug into the passage at the surface of the chuck. The porosity of the plug is selected to ensure a dimension of the pores inhibits plasma formation, yet allows the heat transfer fluid to reach the substrate support surface. While the porous material provides protection against plasma formation, fabrication of such electrostatic chucks is difficult, time consuming and costly. 
         [0009]    Accordingly, there is a need for an improved electrostatic chuck that reduces plasma formation and arcing. 
       SUMMARY 
       [0010]    Embodiments of the invention comprise a method of making an electrostatic chuck comprising positioning a plate into a channel in a body to form a plenum and inserting a dielectric component into an opening in the plate, where the dielectric component defines a portion of a passage from the plenum. Thereafter, depositing a dielectric layer covering at least a portion of the body and at least a portion of the plate to form a support surface. The dielectric layer is polished to a specified thickness. In one embodiment, the polishing process forms an opening through the dielectric layer to enable the dielectric component to define a passage between the support surface and the plenum. In another embodiment, at least a portion of the dielectric layer is porous proximate the dielectric component such that the porous dielectric layer and the dielectric component form a passage between the support surface and the plenum. In a further embodiment, a hole is formed through the dielectric layer and the hole in the dielectric layer and the dielectric component form a passage between the support surface and the plenum. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    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. 
           [0012]      FIG. 1  illustrates a plasma-based substrate processing system comprising an electrostatic chuck having a fluid distribution element according to various embodiments of the present invention; 
           [0013]      FIG. 2  illustrates a top view of the electrostatic chuck of  FIG. 1 ; 
           [0014]      FIG. 2A  illustrates a partial sectional perspective view of a portion of the electrostatic chuck of  FIG. 2 ; 
           [0015]      FIG. 3  illustrates a cross-sectional view of the electrostatic chuck of  FIG. 2  along the line  3 - 3 ; 
           [0016]      FIG. 4  depicts a cross-sectional view of a fluid distribution element of an electrostatic chuck according to one embodiment of the present invention; 
           [0017]      FIG. 5  depicts a cross-sectional view of a fluid distribution element of an electrostatic chuck according to another embodiment; 
           [0018]      FIG. 6  depicts a cross-sectional view of a fluid distribution element for an electrostatic chuck according to another embodiment; 
           [0019]      FIG. 7  depicts a cross-sectional view of a fluid distribution element of an electrostatic chuck according to yet another embodiment of the present invention; 
           [0020]      FIG. 8  depicts a cross-sectional view of a fluid distribution element of an electrostatic chuck according to various embodiments of the present invention; 
           [0021]      FIG. 9  depicts a cross-sectional view of a fluid distribution element of an electrostatic chuck according to various embodiments of the present invention; and 
           [0022]      FIG. 10  depicts a cross-sectional view of a fluid distribution element of an electrostatic chuck according to various embodiments of the present inventions. 
       
    
    
       [0023]    While the invention is described herein by way of example using several embodiments and illustrative drawings, those skilled in the art will recognize that the invention is not limited to the embodiments of drawing or drawings described. It should be understood that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modification, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to. Further, the words “a” or “an” means “at least one” unless otherwise mentioned. 
       DETAILED DESCRIPTION 
       [0024]      FIG. 1  illustrates a plasma-based substrate processing system  36  comprising an electrostatic chuck  68  according to various embodiments of the present invention. The plasma processing system  36  is used for temperature controlled processing of substrates, such as Silicon wafers, GaAs wafers and the like, while creating and maintaining a plasma environment in which to process the substrates. The plasma is created in the vicinity of the substrate for processing the substrate, and the temperature of the substrate is controlled using various techniques, such as, by supplying a heat transfer fluid to the back surface of the substrate. Although one embodiment of a plasma processing chamber is described illustratively in a high density plasma-chemical vapor deposition (HDP-CVD) system such as the 300 mm HDP-CVD Ultima X system available from Applied Materials, Inc. of Santa Clara, Calif., the invention has utility in other process chambers where plasma is used including physical vapor deposition chambers, chemical vapor deposition chambers, etch chambers and other applications where a temperature control of a substrate is desired. 
         [0025]      FIG. 1  illustrates one embodiment of a HDP-CVD system  36 , in which an electrostatic chuck  68  is used to secure a substrate during processing. In accordance with embodiments of the present invention, the electrostatic chuck  68  is designed to reduce plasma penetration and arcing proximate the chuck  68 . 
         [0026]    The system  36  includes a process chamber  38 , a vacuum system  40 , a source plasma system  42 , a bias plasma system  44 , a gas delivery system  46 , and a remote plasma cleaning system  48 . 
         [0027]    An upper portion of process chamber  38  includes a dome  50 , which is made of a dielectric material, such as alumina or aluminum nitride. The dome  50  defines an upper boundary of a plasma processing region  52 . The plasma processing region  52  is bounded on the bottom by the upper surface of substrate  54  and the substrate support member  56 . 
         [0028]    A heater plate  58  and a cold plate  60  surmount, and are thermally coupled to, the dome  50 . The heater plate  58  and the cold plate  60  allow control of the dome temperature to within about +/−10 degree Centigrade over a range of about 100 to 200 degree Centigrade. This allows optimizing the dome temperature for the various processes. For example, it may be desirable to maintain the dome at a higher temperature for cleaning or etching processes than for deposition processes. Accurate control of the dome temperature also reduces the flake or particle counts in the process chamber and improves adhesion between the deposited layer and the substrate. 
         [0029]    The lower portion of process chamber  38  includes a body member  62 , which joins the process chamber to the vacuum system. A base portion  64  of the substrate support member  56  is mounted on, and forms a continuous inner surface with, body member  62 . Substrates are transferred into and out of process chamber  38  by a robot blade (not shown) through an insertion/removal opening  95  in the side of process chamber  38 . A pneumatic actuator (not shown) raises and lowers a lift-pin plate (not shown) that raises and lowers lift pins (not shown) that raise and lower the wafer. Upon transfer into process chamber  38 , substrates are loaded onto the raised lift pins, and then lowered to a substrate receiving portion  66  of substrate support member  56 . Substrate receiving portion  66  includes an electrostatic chuck  68  that secures the substrate to substrate support member  56  during substrate processing. 
         [0030]    The vacuum system  40  includes a throttle body  70 , which houses multi-blade throttle valve  72  and is attached to gate valve  74  and turbomolecular pump  76 . It should be noted that throttle body  70  offers minimum obstruction to gas flow, and allows symmetric pumping, as described in co-pending, commonly assigned United States patent application, originally filed on filed Dec. 12, 1995, and assigned Ser. No. 08/574,839, refiled on Sep. 11, 1996 and assigned Ser. No. 08/712,724 entitled “SYMMETRIC CHAMBER”. The gate valve  74  can isolate the pump  76  from the throttle body  70 , and can also control process chamber pressure by restricting the exhaust flow capacity when throttle valve  72  is fully open. The arrangement of the throttle valve  72 , gate valve  74 , and turbo molecular pump  76  allow accurate and stable control of process chamber pressures from about 1 to 100 millitorr. 
         [0031]    The source plasma system  42  includes a top coil  78  and side coil  80 , mounted on dome  50 . A symmetrical ground shield (not shown) reduces electrical coupling between the coils. Top coil  78  is powered by top RF source generator  82 , while the side coil  80  is powered by side RF source generator  84 , allowing independent power levels and frequencies of operation for each coil. This dual coil system allows control of the radial ion density in process chamber  38 , thereby improving plasma uniformity. Side coil  80  and top coil  78  couple energy into the chamber  38  inductively. In a specific embodiment, the top RF source generator  82  provides up to 8000 W of RF power at nominally 2 MHz and the side RF source generator  84  provides up to 8000 W of RF power at nominally 2 MHz. The operating frequencies of the top and side RF generators may be offset from the nominal operating frequency (e.g., to 1.7-1.9 MHz and 1.9-2.1 MHz, respectively) to improve plasma-generation efficiency. 
         [0032]    The RF generators  82  and  84  include digitally controlled synthesizers and operate over a frequency range from about 1.7 to about 2.1 MHz. Each generator includes an RF control circuit (not shown) that measures reflected power from the process chamber and coil back to the generator, and adjusts the frequency of operation to obtain the lowest reflected power, as understood by a person of ordinary skill in the art. RF generators are typically designed to operate into a load with a characteristic impedance of 50 ohms. RF power may be reflected from loads that have a different characteristic impedance than the generator. This can reduce power transferred to the load. Additionally, power reflected from the load back to the generator may overload and damage the generator. Because the impedance of a plasma may range from less than 5 ohms to over 900 ohms, depending on the plasma ion density among other factors, and because reflected power may be a function of frequency, adjusting the generator frequency according to the reflected power increases the power transferred from the RF generator to the plasma and protects the generator. Another way to reduce reflected power and improve efficiency is with a matching network. 
         [0033]    Matching networks  89  and  90  match the output impedance of generators  82  and  84  with coils  78  and  80 , respectively. The RF control circuit may tune both matching networks by changing the value of capacitors within the matching networks to match the generator to the load as the load changes. The RF control circuit may tune a matching network when the power reflected from the load back to the generator exceeds a certain limit. One way to provide a constant match, and effectively disable the RF control circuit from tuning the matching network, is to set the reflected power limit above any expected value of reflected power. This may help stabilize a plasma under some conditions by holding the matching network constant at its most recent condition. 
         [0034]    The bias plasma system  44  includes a RF bias generator  86  and a bias matching network  88 . The bias plasma system  44  capacitively couples substrate receiving portion  66  to the body member  62 , which act as complementary electrodes. The bias plasma system  44  serves to enhance the transport of plasma species created by the source plasma system  42  to the surface of the substrate. In a specific embodiment, the RF bias generator  86  provides up to 10000 W of RF power at 13.56 MHz. 
         [0035]    Other measures may also help stabilize a plasma. For example, the RF control circuit can be used to determine the power delivered to the load (plasma) and may increase or decrease the generator output power to keep the delivered power substantially constant during deposition of a layer. 
         [0036]    The gas delivery system  46  includes a plurality of gas sources  100   a ,  100   b ,  100   c ,  100   d  and  100   e . In one embodiment, the aforementioned gas sources comprise of silane, molecular oxygen, helium and argon, respectively. The gas delivery system  46  provides gases from several sources to the process chamber for processing the substrate via gas delivery lines  92  (only some of which are shown). Gases are introduced into the process chamber  38  through a gas ring  94 , a top nozzle  96 , and a top vent  98 . Specifically, gas sources,  100   a  and  100   d , provide gas to top nozzle  96  via flow controllers  120   a  and  120   c , respectively, and gas delivery lines  92 . Gas from gas source  100   b  is provided to gas vent  98  via flow controller  120   b . The top nozzle  96  and top vent  98  allow independent control of top and side flows of the gases, which improves film uniformity and allows fine adjustment of the film&#39;s deposition and doping parameters. The top vent  98  is an annular opening around the top nozzle  96  through which gas may flow into the process chamber from the gas delivery system. 
         [0037]    Gas is provided from each of the aforementioned gas sources to gas ring  94  via flow controller  102   a ,  102   b ,  102   c ,  102   d  and  102   e  and gas delivery lines  92 . Gas ring  94  has a plurality of gas nozzles  106  and  108  (only two of which is shown) that provide a uniform flow of gas over the substrate. Nozzle length and nozzle angle may be changed by changing gas ring  94 . This allows tailoring the uniformity profile and gas utilization efficiency for a particular process within an individual process chamber. In a specific embodiment, the gas ring  94  has a total of thirty-six gas nozzles, twenty-four first gas nozzles  108  and twelve second gas nozzles  106 . Typically, gas nozzles  108  (only one of which is shown), are coplanar with, and shorter than, the second gas nozzles  106 . 
         [0038]    In some embodiments, flammable, toxic, or corrosive gases may be used. In these instances, it may be desirable to eliminate gas remaining in the gas delivery lines after a deposition. This may be accomplished using a three-way valve, such as valve  112 , to isolate process chamber  38  from delivery line  92   a , and to vent delivery line  92   a  to vacuum foreline  114 , for example. As shown in  FIG. 1 , other similar valves, such as  112   a  and  112   b , may be incorporated on other gas delivery lines. Such three-way valves may be placed as close to process chamber  38  as practical, to minimize the volume of the unvented gas delivery line (between the three-way valve and the process chamber). Additionally, two-way (on-off) valves (not shown) may be placed between a mass flow controller (MFC) and the process chamber or between a gas source and an MFC. 
         [0039]    The system  36  may further include a remote cleaning RF plasma source (not shown) for providing a cleaning gas to the top nozzle  96  of the chamber  38 . In other embodiments, cleaning gas (if used) may enter the chamber  38  at other locations. 
         [0040]    A system controller  132  regulates the operation of system  36  and includes a processor  134  in electrical communication therewith to regulate the operations thereof. Typically, the processor  134  is part of a single-board computer (SBC), that includes analog and digital input/output boards, interface boards and stepper motor controller boards. Various components of the CVD system  36  conform to the Versa Modular European (VME) standard, which defines board, card cage, as well as connector type and dimensions. The VME standard also defines the bus structure as having a 16-bit data bus and a 24-bit address bus. The processor  134  executes system control software, which is a computer program stored in a memory  136 , electronically coupled to the processor  134 . Any type of memory device may be employed, such as a hard disk drive, a floppy disk drive, a card rack or a combination thereof. The system control software includes sets of instructions that dictate the timing, mixture of gases, process chamber pressure, process chamber temperature, microwave power levels, pedestal position, and other parameters of a particular process 
         [0041]    Temperature of the substrate  104  and uniformity of the substrate temperature are important processing parameters for processing the substrate  104 . To generate a uniform temperature profile, a heat transfer fluid is applied between the chuck  68  and the back surface of the substrate  104 . One embodiment of the invention uses, for example, helium as the heat transfer fluid. Generally, the electrostatic chuck  68  is circular in shape, but alternatively, the electrostatic chuck  68  may comprise various regular and irregular geometries to accommodate non-circular substrates, for example, square or rectangular substrate such as flat panels. 
         [0042]    In operation, the substrate  104  is placed on the electrostatic chuck  68  and multiple gaseous components are supplied from gas panel  46  into the processing region  52  of the plasma processing chamber  38  to form a gaseous mixture. To ignite a plasma, RF power is applied to one or more of an electrode in the substrate support member  56 , the top coil  78 , or side coil  80 . To maintain temperature uniformity of the substrate during processing, a heat transfer fluid, such as helium gas, is supplied via at least one fluid distribution element (shown and discussed below) in accordance with the embodiments of the present invention. 
         [0043]      FIG. 2  illustrates a top plan view of the electrostatic chuck  68  having the fluid distribution element  222  according to one embodiment of the present invention.  FIG. 2A  depicts a partial sectional perspective view of the electrostatic chuck  68  of  FIG. 2 .  FIG. 3  depicts a cross-sectional view of the chuck  68  of  FIG. 2  taken along line  3 - 3 . The following disclosure is best understood by simultaneously viewing  FIGS. 2 and 3 . The electrostatic chuck  68  comprises a body  220 , a fluid distribution element  222 , and a dielectric layer  224 . In one embodiment of the electrostatic chuck  68 , the body  220  is fabricated of a conductive material such as aluminum and the dielectric layer  224  is a ceramic material such as aluminum-nitride, alumina, and the like. The fluid distribution element  222  is disposed circumferentially near the periphery of the electrostatic chuck  68 . The fluid distribution element  222  comprises multiple holes  230  (or other forms of passages) penetrating the dielectric layer  224  for distributing a fluid such as helium gas from the electrostatic chuck to the back surface of the substrate. For the electrostatic chuck  102  used in combination with an 12 inch (300 mm) diameter semiconductor wafer, there are between 60 to 360 holes around the periphery of the electrostatic chuck  102 . Each of the multiple holes  230  typically ranges from about 0.15 mm diameter. These dimensions are adjusted depending on the kind of fluid distribution element used, the pressures used within the processing chamber, and the amount of gas flow through the fluid distribution element  222 . 
         [0044]    The fluid distribution element  222  has a ring-shaped structure. However, in alternate embodiments, the fluid distribution element  222  may have various geometrical designs as per the need of the processing methods and a user including multiple rings, radial arms, combinations of radials and rings, and so on. The embodiments of the invention do not limit the geometry of the fluid distribution element or elements. 
         [0045]    The dielectric layer  224  covers at least a portion of the top surface of the body  220  and at least a portion of the fluid distribution element  222  thereby forming a support surface  228 . The support surface  228  supports the substrate  104  placed thereon. The dielectric layer  224  may be sprayed onto the top surface of the body and polished to a desired thickness. 
         [0046]    The body  220  comprises the top surface  332  and a channel  334  that is formed into top surface  332  of the body  220 . Generally, the channel  334  has a rectangular cross-sectional shape. However, in alternate embodiments the channel  334  may have various geometrical cross-sectional shapes. The fluid distribution element  222  is coupled to the body  220  such that the channel  334  and the fluid distribution element  222  form a plenum  336  i.e., the element  222  is positioned into the channel  334  and fixed thereto. Further, the body  220  comprises a conduit  338  connected to the channel  334  for providing fluids to the plenum  336 . According to one embodiment of the present invention, the cooling gas may be supplied through the conduit  338  and distributed by the plenum to the fluid distribution element  222 . The gas exits through one or more of the multiple holes  230  (or other forms of passages) thereby supplying a heat transfer medium to the back surface of a substrate. 
         [0047]      FIGS. 4 to 10  illustrate cross-section views of the dotted line portion  230  of an electrostatic chuck, for example, the electrostatic chuck  102 , the portion having a fluid distribution element  222 , dielectric layer  228  and the body  220 . In the illustrations, the dimensions of the electrostatic chuck have been exaggerated to illustrate the cross-section of the fluid distribution element and the body. 
         [0048]    In particular,  FIG. 4  illustrates a portion of an electrostatic chuck  402  according to one embodiment of the present invention. The body  220  comprises a dual damascene channel  404  having a lower channel  404 A and an upper channel  404 B, where the lower channel  404 A is narrower than the upper channel  404 B. The electrostatic chuck  402  includes a fluid distribution element  422  comprising a plate  440  and a dielectric tube  442 . The plate  440  fits into the upper channel  404 B (e.g., the plate has a circular plan form to match the channel  404 ) such that the base  406  of the upper channel  404 B forms a stop. The height of the plate  440  is substantially the same as the height of the upper channel  404 B such that the top  408  of the plate  440  is substantially coplanar with the top  332  of the body  220 . The plate  440  may be fabricated of a conductive material such as aluminum and welded into place in the upper channel  404 B. The plate  440  further comprises a channel  410  formed in the bottom surface of the plate  440 . In one embodiment of the invention, the width of channel  410  is substantially similar to the width of lower channel  404 A; however, in other embodiments, the channel  410  may have a narrower width than lower channel  404 A. The combination of the lower channel  404 A and the channel  410  defines a plenum  336 . 
         [0049]    A dielectric tube  442  (an electrical isolator) comprises a first end  446 , a second end  448 , and an axial through hole  450 . The dielectric tube  442 , for example, made of alumina, has a diameter substantially matching the diameter of an opening  444  in the plate  440 . The diameter of the opening  444  is generally, but not by way of limitation, about 0.008 inches (about 0.2 mm) or larger. In alternate embodiments, the opening  444  may have various geometrical shapes such as circular, rectangular, square, and the like. Moreover, the shape and size of the opening substantially matches to the shape and size of an outer diameter of the dielectric tube  442 . The dielectric tube  442  is positioned (e.g., press fit) into the opening  444 . The opening  444  comprises a flange  412  upon which the tube  442  rests (i.e., the flange forms a stop). In the depicted embodiment, the first end  446  of the tube  442  extends above the surface  332  of the body  220 . In other embodiments, the first end  446  of the tube  442  may be coplanar with the surface  332 . 
         [0050]    At least a portion of the body  220  and at least a portion of the fluid distribution element  422  are covered by the dielectric layer  224  thereby forming the support surface  428 . The dielectric layer  224  may be sprayed onto the top surface of the body and polished to a desired thickness. In one embodiment, the dielectric layer  224  comprises thermally sprayed Alumina or sprayed Alumina/Titania. Processes for application of this thermally sprayed dielectric layer are known in the art. The thermal spraying process can be selected from several different methods such as plasma spraying, detonation gun spraying, high velocity oxygen fuel (HVOF) spraying and flame spraying. 
         [0051]    In one embodiment, the dielectric layer  224  is polished to a thickness represented by line  414  such that the surface  428  of the layer  224  is coplanar with the end  446  of the tube  442 . Alternatively, the dielectric layer  224  may be a porous ceramic such that the layer  224  is polished to a specific flatness, but the layer  224  covers at least the first end  446  of the tube  442 . Due to the porosity of the ceramic, gas from the plenum flows through the tube  442  and the dielectric layer  224 . For example, the dielectric layer  224  proximate the first end  446  of the tube  442  may be wholly or partially formed of alumina with a porosity of between 10 and 60 percent by volume that results in pore diameters of about 1 to 100 um. In some embodiments, as discussed below with respect to  FIG. 8 , the dielectric layer may be porous proximate the end  446  of the tube  442 , and less porous elsewhere. As illustrated, the passage  445  advantageously lacks a direct line-of-sight path from the support surface  428  to the plenum  436  thereby limiting the potential for formation of a plasma in the passage  445 . In another embodiment, the dielectric layer  224  is polished to a specific flatness with the layer  224  covering the first end  446  of the tube  442 . A hole  416  can be bored or otherwise formed (e.g., laser drilling) through the dielectric layer  416  into the passage  445 . The boring process only bores through the dielectric material, i.e., the conductive material of the body is not sputtered by the boring process. 
         [0052]    As known in the art, the support surface  428  may further be processed to provide a pattern of grooves (not shown in the figure) made onto the dielectric layer  224 . The grooves are machined or otherwise formed into the support surface  428  so that they intersect with the passage  445 . The cooling gas can proceed from passage  445  and into the grooves for distributing the cooling gas uniformly over the entire support surface  428  of electrostatic chuck  402 . 
         [0053]    By using an electrical isolator (the dielectric tube and/or the dielectric layer) to define the passage between the plenum and the substrate surface, the possibility for plasma formation from the heat transfer gas or arcing caused by plasma formation is reduced. By reducing or eliminating plasma formation and arcing, the life of an electrostatic chuck is significantly increased. The use of an isolator, reduces the electric fields in the passage; thus, reducing the chance for plasma formation. In addition, certain embodiments of the invention utilize a fluid distribution element structure that further reduces the electric fields in the passage by eliminating a line of sight path between the substrate support surface (where high electric fields exist) and the conductive surface of a plenum. When such a line-of-sight path exists, the volume of fluid in the passage is sufficient to be ignited into a plasma. Using a non-line-of-sight path reduces the electric fields that are established across sufficiently large volumes of fluid that might result in plasma formation. As such, plasma formation and associated arcing are reduced or eliminated. 
         [0054]      FIG. 5  illustrates a cross-section of a portion an electrostatic chuck  502  according to another embodiment of the present invention. Similar to the embodiment of  FIG. 4 , a dielectric tube  542  is positioned through the plate  440 . In this alternative embodiment, the tube  542  extends to the bottom of the channel  534  where a second end  548  of the tube  542  rests upon a supporting element (e.g., a step  556 ) formed in the bottom of the channel  534 . As in the previous embodiment, the dielectric tube  542  and/or the portion of dielectric layer  224  forms an electrical isolator that defines a passage  545  for the fluid from a plenum  536  to the surface  528 . 
         [0055]      FIG. 6  illustrates a cross-section of a portion the electrostatic chuck  602  according to another embodiment of the present invention. Similar to the embodiments of  FIGS. 4 and 5 , a dielectric tube  642  is positioned through the plate  440 . In this alternative embodiment, the dielectric tube  642  comprises at least one notch  656  formed in the second end  604 . In an alternative embodiment, the tube  642  may comprise holes to facilitate fluid flow from the plenum  636  to a passage  645  in the tube  642 . As with prior embodiments, the dielectric layer  224  may be porous and cover a first end  606  of the tube  642 , the layer  224  may be polished to expose the first end  606  of tube  642 , or a hole formed in the layer to access the passage  645 . The dielectric tube  642  and the portion of dielectric layer  224  forms a passage  645  for the fluid from a plenum  636 . As illustrated, when the dielectric layer  224  is porous and covers the tube  642 , the passage  645  advantageously lacks a direct line-of-sight path from the support surface  628  to the plenum  636  thereby limiting formation of a plasma in the passage  645 . 
         [0056]      FIG. 7  illustrates a cross-section of a portion of an electrostatic chuck  702  according to yet another embodiment of the present invention. The electrostatic chuck  702  comprises a body  720  and fluid distribution element  722 . The fluid distribution element  722  comprises a plate  740  and a dielectric tube  742  that are assembled in the same manner as the previous embodiments. In this embodiment, the body  720  comprises a channel  734  comprising a dielectric end cap  760 . The dielectric end cap  760  is positioned at the bottom of the channel  734 . The dielectric end cap  760  comprises an opening  762  such that the cap  760  is cup shaped. The dielectric tube  742  comprises a first end  746 , a second end  748 , and an axial through hole  750  connecting the first end  746  and the second end  748 . In one embodiment of the invention, the dielectric layer  724  covers the first end  746  of the tube  742  and, in a second embodiment, the dielectric layer  724  is polished to line  414  to expose the first end  746  of the tube  742 . The dielectric cap  760  is positioned into the channel  734  such that the second end  748  of the tube  742  extends into the opening  762 , but is spaced apart therefrom to form a gap. The tube  742  and the end cap  760  form a labyrinth channel through which the fluid flows. Using such a channel ensures that a line-of-sight path from the conductive plenum walls to the chuck surface does not exist. 
         [0057]      FIG. 8  illustrates a cross-section of a portion an electrostatic chuck  802  according to another embodiment of the present invention. The electrostatic chuck  802  comprises a fluid distribution element  822 . The fluid distribution element  822  comprises a plate  840  comprising an opening  844 . The plate  840  is coupled to a body  820  such that a channel  834  and the plate  840  form a plenum  836 . A dielectric layer  824  covers at least a portion of the body  820  and at least a portion of the fluid distribution element  822 . The dielectric layer  824  comprises a porous dielectric segment  870  such that at least a portion of the porous dielectric segment  870  overlaps the opening  844 . The porous dielectric segment  870  is a porous ceramic, such as alumina having a porosity ranging from about 10% in volume to about 60% in volume, with interconnected openings that form continuous passageways through the porous dielectric segment  870 . The opening  844  and at least a portion of the porous dielectric segment  870  form a passage  845  for the fluid to flow from the plenum  836  to the support surface  828  of the electrostatic chuck  802 . As illustrated, the passage  845  advantageously lacks direct line-of-sight path from the support surface  828  to the conductive plenum  836  thereby inhibiting formation of a plasma into the passage  845 . 
         [0058]      FIG. 9  illustrates a cross-section of a portion an electrostatic chuck  902  according to another embodiment of the present invention. The electrostatic chuck  902  comprises a fluid distribution element  922 . The fluid distribution element  922  comprises a plate  940  having an opening  944  and a dielectric plug  980 . The plate  940  is coupled to a body  920  such that a channel  934  and the plate  940  form a plenum  936 . The plate  940  and body  920  are assembled as discussed above with respect to the other embodiments of the invention. Diameter of the dielectric plug  980  substantially matches with the diameter of the opening  944 . The dielectric plug  980  is positioned in the opening  1044  and generally press fit therein. The dielectric layer  224  covers at least a portion of the body  920  and at least a portion of the fluid distribution element  922  thereby forming a support surface  928 . The dielectric layer  224  may be sprayed onto the top surface of the body  920  and the fluid distribution element  922 , and polished to a desired thickness. A hole  982  is formed through the dielectric layer  224  and through the dielectric plug  980 . The hole  982  enables flow of the fluid from the plenum  936  to the support surface  928  of the electrostatic chuck  902 . The hole  982  may be formed using various techniques such as mechanical drilling, laser drilling and the like. The hole  982  is formed through only dielectric material. As such, no metallic residue from the drilling process can form on the axial through hole  982 . Without such metallic residue, the possibility of plasma formation or arcing in the hold  982  is limited. 
         [0059]      FIG. 10  illustrates a cross-section of a portion an electrostatic chuck  1002  according to another embodiment of the present invention. The electrostatic chuck  1002  comprises a fluid distribution element  1022 . The fluid distribution element  1022  comprises a plate  1040  and a dielectric cap  1042 . The plate  1040  comprises two circular rings  1040 A and  1040 B. The ring  1040 A has a smaller diameter than ring  1040 B. Each ring  1040 A and  1040 B rests upon the ledge  406  formed at the bottom of the upper channel  404 B. The plate  1040  is welded to the body  1020  to retain the plate in the upper channel  404 B. The dielectric cap  1042  (ring shaped to form the plenum  1036 ) is inserted into the upper channel  404 B and rests upon the plate  1040 . 
         [0060]    In another embodiment, the plate  1040  may comprise an inverted U-shaped cross-section (e.g., the plate  440  of  FIG. 4 ) having a plurality of counter-sunk holes. A circular (donut-shaped) dielectric element having a cross-section similar to the element  1042  may be inserted into such a counter-sunk hole. The fluid distribution element  1022  is coupled to a body  1020  such that the fluid distribution element  1022  and a channel  1034  form a plenum  1036 . The dielectric layer  224  covers at least a portion of the body  1020  and at least a portion of the fluid distribution element  1022 , thereby forming a support surface  1028 . The dielectric layer  224  may be sprayed onto the top surface of the body  1020  and the fluid distribution element  1022  and polished to a desired thickness. A hole  1082  is formed through the dielectric layer  224  and the dielectric cap  1090 . The hole  1082  may be drilled using various techniques such as mechanical drilling, laser drilling and the like. As with the embodiment of  FIG. 9 , the hole  1082  is formed through dielectric material only. As such, no conductive residue remains in the hole  1082 . 
         [0061]    In each of the foregoing embodiments, in the unlikely occurrence that an electrostatic chuck utilizing the inventive fluid distribution element(s) is damaged by plasma formation or arcing, the chuck can be easily repaired using a number of methods. Generally, a damaging plasma formation or arcing will occur proximate or within a dielectric component (tube, porous insert, and the like). As such, the dielectric layer can be removed locally (over the dielectric component) or globally (across the entire chuck) to expose the dielectric component. The component can then be removed using an extraction tool to drill out or pull out the component. Once removed, a new dielectric component can be inserted and the dielectric layer replaced either locally or globally as needed. In some embodiments, the dielectric component may extend to the support surface of the chuck (as discussed above) and not require removal of the dielectric layer before extraction. In those situation, the damaged dielectric component is removed and a new dielectric component is inserted (generally press fit) into the opening in the plate. In this manner, an electrostatic chuck can be repaired at substantial savings when compared to replacing an entire electrostatic chuck upon arcing or plasma formation in or near the heat transfer fluid passages. 
         [0062]    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.