Patent Publication Number: US-2023162954-A1

Title: High temperature detachable very high frequency (vhf) electrostatic chuck (esc) for pvd chamber

Description:
FIELD 
     Embodiments of the present disclosure generally relate to substrate processing equipment. 
     BACKGROUND 
     Substrate supports are used for providing support to substrates within substrate processing systems, such as a plasma processing chamber. A type of substrate support includes an electrostatic chuck (ESC) coupled to a lower assembly. An ESC generally includes one or more electrodes embedded within a ceramic chuck body to retain a substrate. An ESC may be detachable from the lower assembly to reduce preventative maintenance time and reduce cost of replacement. However, conventional ESCs are not efficient at RF frequencies around 60 MHz combined with higher temperatures (&gt;400 degrees Celsius). At such frequencies and temperatures, the ESC has a high impedance that prevents efficient RF delivery through the ESC and leads to lower throughput. 
     Accordingly, the inventors have provided improved substrate supports for use with high RF frequencies. 
     SUMMARY 
     Embodiments of substrate supports for use in substrate processing chambers are provided herein. In some embodiments, a substrate support for use in a substrate processing chamber includes: an upper assembly having a base plate assembly coupled to a lower surface of a cooling plate, wherein the base plate assembly includes a plurality of electrical feedthroughs, and wherein the cooling plate includes a plurality of openings aligned with the plurality of electrical feedthroughs; an electrostatic chuck disposed on the upper assembly and removably coupled to the cooling plate, wherein the electrostatic chuck has a chucking electrode disposed therein that is electrically coupled to a first pair of electrical feedthroughs of the plurality of electrical feedthroughs; and an inner tube coupled to the cooling plate and configured to provide an RF delivery path to the electrostatic chuck via at least one of: a gap between the electrostatic chuck and the cooling plate, or backside metallization of the electrostatic chuck. 
     In some embodiments, a substrate support for use in a substrate processing chamber, includes: an upper assembly having a base plate assembly coupled to a cooling plate, wherein the base plate assembly includes a plurality of electrical feedthroughs disposed about a backside gas opening, and wherein the cooling plate includes a plurality of openings aligned with the plurality of electrical feedthroughs; an electrostatic chuck disposed on the upper assembly and removably coupled to the cooling plate, wherein the electrostatic chuck has an electrode disposed therein that is electrically coupled to a first pair of electrical feedthroughs of the plurality of electrical feedthroughs; an inner tube coupled to the cooling plate and configured to provide an RF delivery path to the electrostatic chuck via at least one of: a gap between the electrostatic chuck and the cooling plate, or backside metallization of the electrostatic chuck; and a first resistive heater embedded in the electrostatic chuck and electrically coupled to a second pair of the electrical feedthroughs. 
     In some embodiments, a process chamber, includes: a chamber body having a substrate support disposed within an inner volume of the chamber body, wherein the substrate support comprises: an upper assembly having a base plate assembly coupled to a cooling plate, wherein the base plate assembly includes a plurality of electrical feedthroughs disposed about a backside gas opening, and wherein the cooling plate includes a plurality of openings aligned with the plurality of electrical feedthroughs; an electrostatic chuck disposed on the upper assembly and removably coupled to the cooling plate, wherein the electrostatic chuck has an electrode disposed therein that is electrically coupled to a first pair of electrical feedthroughs of the plurality of electrical feedthroughs; and a support assembly having an inner tube coupled to the cooling plate and configured to provide an RF delivery path to the electrostatic chuck via at least one of: a gap between the electrostatic chuck and the cooling plate, or backside metallization of the electrostatic chuck. 
     Other and further embodiments of the present disclosure are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments. 
         FIG.  1    depicts a schematic side view of a process chamber having a substrate support in accordance with at least some embodiments of the present disclosure. 
         FIG.  2    depicts a schematic side view of the substrate support in accordance with at least some embodiments of the present disclosure. 
         FIG.  3    depicts an isometric top view of a cooling plate in accordance with as least some embodiments of the present disclosure. 
         FIG.  4    depicts an isometric bottom view of a cooling plate in accordance with at least some embodiments of the present disclosure. 
         FIG.  5    depicts a cross-sectional side view of a closeup of an upper portion of a substrate support in accordance with at least some embodiments of the present disclosure. 
         FIG.  6    depicts an interface between an electrostatic chuck and a cooling plate in accordance with at least some embodiments of the present disclosure. 
         FIG.  7 A  depicts a backside metallization pattern on a backside of an electrostatic chuck in accordance with at least some embodiments of the present disclosure. 
         FIG.  7 B  depicts a schematic side view of an electrostatic chuck with a backside metallization pattern in accordance with at least some embodiments of the present disclosure. 
         FIG.  8    depicts an isometric top view of a base plate in accordance with at least some embodiments of the present disclosure. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     Embodiments of detachable electrostatic chucks (ESC) for physical vapor deposition (PVD) chambers operating at very high RF frequencies are provided herein. Very high RF frequencies may, for example, be about 40 MHz or more, or about 60 MHz or more. The inventors have found that PVD chambers operating at very high frequencies may advantageously lower resistivity of film being deposited therein. The ESC may also operate at high temperatures (about 400 degrees Celsius or more). 
       FIG.  1    depicts a schematic side view of a process chamber  100  having a substrate support in accordance with at least some embodiments of the present disclosure. In some embodiments, the process chamber  100  is a PVD chamber. However, other types of processing chambers configured for different processes can also use or be modified for use with embodiments of the electrostatic chuck described herein. 
     The process chamber  100  is a vacuum chamber which is suitably adapted to maintain sub-atmospheric pressures within an interior volume  120  of the process chamber  100  during substrate processing. The process chamber  100  includes a chamber body  106  covered by a lid  104  which encloses a processing volume  119  located in the upper half of the interior volume  120 . The process chamber  100  may also include a process shield  105  circumscribing various chamber components to prevent unwanted reaction between such components and ionized process material. The chamber body  106  and lid  104  may be made of metal, such as aluminum. The chamber body  106  may be grounded via a coupling to ground  115 . 
     A substrate support  124  is disposed within the interior volume  120  to support and retain a substrate  122 , such as a semiconductor wafer, for example, or other such substrate as may be electrostatically retained. The substrate support  124  may generally comprise an electrostatic chuck  150  disposed on a pedestal  136 . The electrostatic chuck  150  may be made of a ceramic material. The pedestal  136  is coupled to a support assembly  103  for supporting the pedestal  136  and the electrostatic chuck  150 . 
     The support assembly  103  generally includes an inner tube  112  that is hollow and a bellows assembly  110  disposed about the inner tube  112 . The inner tube  112  is configured to provide an RF delivery path from the RF bias power supply  117  to the electrostatic chuck  150 . The inner tube  112  also provides a conduit to provide, for example, backside gases, process gases, fluids, coolants, power, auto capacitive tuner (ACT), or the like, to the electrostatic chuck  150 . The bellows assembly  110  may include an outer tube  114  disposed about the inner tube  112 . In some embodiments, the outer tube  114  is configured to provide an RF return path from the pedestal  136 . In some embodiments, a lower end of the inner tube  112  may protrude beyond a lower end of the outer tube  114  to facilitate electrical connection to the inner tube  112  and the outer tube  114 . 
     The electrostatic chuck  150  includes one or more chucking electrodes  154  disposed therein. A temperature of the electrostatic chuck  150  may be adjusted to control the temperature of the substrate  122 . For example, the electrostatic chuck  150  may be heated using one or more heating elements (e.g., see  FIG.  5   ) that are embedded, such as a resistive heater. In some embodiments, a thickness of the electrostatic chuck  150  may be about 6.0 mm or less. 
     In some embodiments, the inner tube  112  is coupled to a lift mechanism  113 , such as an actuator or motor, which provides vertical movement of the electrostatic chuck  150  between an upper, processing position (as shown in  FIG.  1   ) and a lower, transfer position (not shown). 
     The bellows assembly  110  is coupled between the electrostatic chuck  150  and a bottom surface  126  of process chamber  100  to provide a flexible seal that allows vertical motion of the electrostatic chuck  150  while preventing loss of vacuum from within the process chamber  100 . The bellows assembly  110  may also include a lower bellows flange  164  in contact with an o-ring  165  or other suitable sealing element which contacts the bottom surface  126  to help prevent loss of chamber vacuum. The bellows assembly  110  may facilitate or partially define an RF return path from the lower assembly  220 . 
     The inner tube  112  provides a conduit for coupling a backside gas supply  141 , a chucking power supply  140 , a heater power supply  160 , to the electrostatic chuck  150 . The backside gas supply  141  is disposed outside of the chamber body  106  and supplies gas to the electrostatic chuck  150  via a gas conduit  146  to control the temperature or pressure and/or a temperature profile or pressure profile on the support surface of the electrostatic chuck  150  during use. In some embodiments, RF power supply  174  and RF bias power supply  117  are coupled to the electrostatic chuck  150  via respective RF match networks (only RF match network  116  shown). In some embodiments, the substrate support  124  may alternatively include AC, DC, or RF bias power. 
     The RF delivery path and the RF return path are arranged in a coaxial manner along the support assembly  103 . For example, the RF delivery path extends along the inner tube  112 , which acts as an RF electrode. The inner tube  112  may be maintained at a constant temperature. The RF return path extends along the outer tube  114  disposed about the inner tube  112 . The arrangement of the inner tube  112  and the outer tube  114  creates a neutral or field free region within the inner tube  112 , reducing RF loses due to RF coupling of electrostatic chuck wires, heater wires, thermocouple wires, and the like. 
     A substrate lift  130  can include lift pins  109  mounted on a platform  108  connected to a shaft  111  which is coupled to a second lift mechanism  132  for raising and lowering the substrate lift  130  so that the substrate  122  may be placed on or removed from the electrostatic chuck  150 . The electrostatic chuck  150  may include thru-holes to receive the lift pins  109 . A bellows assembly  131  is coupled between the substrate lift  130  and bottom surface  126  to provide a flexible seal which maintains the process chamber vacuum during vertical motion of the substrate lift  130 . 
     The process chamber  100  is coupled to and in fluid communication with a vacuum system  184  which includes a throttle valve (not shown) and vacuum pump (not shown) which are used to exhaust the process chamber  100 . The pressure inside the process chamber  100  may be regulated by adjusting the throttle valve and/or vacuum pump. The process chamber  100  is also coupled to and in fluid communication with a process gas supply  118  which may supply one or more process gases to the process chamber  100  for processing the substrate  122  disposed therein. 
     A target  138  is disposed in the processing volume  119  opposite the substrate support  124  to at least partially define a process volume therebetween. The target  138  includes a cathode surface defined by processing volume facing surfaces of the target  138 . The substrate support  124  has a support surface having a plane substantially parallel to a sputtering surface of the target  138 . The target  138  is connected to one or both of a DC power source  190  and/or the RF power supply  174 . The DC power source  190  can apply a bias voltage to the target  138  relative to the process shield  105 . 
     The target  138  comprises a sputtering plate  142  mounted to a backing plate  144 . The sputtering plate  142  comprises a material to be sputtered onto the substrate  122 . The backing plate  144  is made from a metal, such as, for example, stainless steel, aluminum, copper-chromium or copper-zinc. The backing plate  144  can be made from a material having a thermal conductivity that is sufficiently high to dissipate the heat generated in the target  138 , which form from eddy currents that arise in the sputtering plate  142  and the backing plate  144  and also from the bombardment of energetic ions from generated plasma onto the sputtering plate  142 . 
     In some embodiments, the process chamber  100  includes a magnetic field generator  156  to shape a magnetic field about the target  138  to improve sputtering of the target  138 . The capacitively generated plasma may be enhanced by the magnetic field generator  156  in which, for example, a plurality of magnets  151  (e.g., permanent magnet or electromagnetic coils) may provide a magnetic field in the process chamber  100  that has a rotating magnetic field having a rotational axis that is perpendicular to the plane of the substrate  122 . The magnetic field generator  156  may include a motor assembly that rotates the plurality of magnets  151 . The magnetic field generator  156  may generates a magnetic field near the target  138  to increase an ion density in the processing volume  119  to improve the sputtering of the target material. The plurality of magnets  151  may be disposed in a cavity  153  in the lid  104 . A coolant such as water may be disposed in or circulated through the cavity  153  to cool the target  138 . 
     The process chamber  100  includes a process kit  102  circumscribing various chamber components to prevent unwanted reaction between such components and ionized process material. The process kit  102  includes a process shield  105  surrounding the substrate support  124  and the target  138  to at least partially define the processing volume  119 . For example, the process shield  105  may define an outer boundary of the processing volume  119 . In some embodiments, the process shield  105  is made of a metal such as aluminum. 
     In some embodiments, the process kit  102  includes a deposition ring  170  that rests on an outer edge of the electrostatic chuck  150 . In some embodiments, the process kit  102  includes a cover ring  180  disposed on the process shield  105  to form a tortuous gas flow path therebetween. In some embodiments, in the processing position, a radially inner portion of the cover ring  180  rests on the deposition ring  170  to reduce or prevent plasma leak therebetween. 
     In some embodiments, a plurality of ground loops  172  are disposed between the process shield  105  and the pedestal  136 . The ground loops  172  may generally comprise a loop of conductive material, or alternatively, conductive straps, spring members, or the like, configured to ground the process shield  105  to the pedestal  136  when the substrate support  124  is in the processing position. In some embodiments, the plurality of ground loops  172  are coupled to an outer lip of the pedestal  136  so that in the processing position, the ground loops  172  contact the process shield  105  to ground the process shield  105 . In some embodiments, in the transfer position, the ground loops  172  are spaced from the process shield  105 . 
     The process chamber  100  is coupled to and in fluid communication with a vacuum system  19  which includes a throttle valve (not shown) and vacuum pump (not shown) which are used to exhaust the process chamber  100 . The pressure inside the process chamber  100  may be regulated by adjusting the throttle valve and/or vacuum pump. The process chamber  100  is also coupled to and in fluid communication with a process gas supply  118  which may supply one or more process gases to the process chamber  100  for processing the substrate  122  disposed therein. A slit valve  148  may be coupled to the chamber body  106  and aligned with an opening in a sidewall of the chamber body  106  to facilitate transferring the substrate  122  into and out of the chamber body  106 . 
     In use, while the DC power source  190  supplies power to the target  138  and other chamber components connected to the DC power source  190 , the RF power supply  174  energizes the sputtering gas (e.g., from the process gas supply  118 ) to form a plasma of the sputtering gas. The plasma formed impinges upon and bombards the sputtering surface of the target  138  to sputter material off the target  138  onto the substrate  122 . In some embodiments, RF energy supplied by the RF power supply  174  may range in frequency from about 2 MHz to about 60 MHz or greater. In some embodiments, a plurality of RF power sources may be provided (i.e., two or more) to provide RF energy in a plurality of the above frequencies. An additional RF power source, (e.g., RF bias power supply  117 ) can also be used to supply a bias voltage to the substrate support  124  to attract ions from the plasma towards the substrate  122 . The RF bias power supply  117  may supply RF power in a very high frequency range, for example, about 13 MHz or greater, or about 40 or about 60 MHz or greater. 
       FIG.  2    depicts a schematic side view of the substrate support  124  in accordance with at least some embodiments of the present disclosure. The pedestal  136  may comprise an upper assembly  210  and a lower assembly  220 . The upper assembly  210  generally includes a base plate assembly  208  coupled to a cooling plate  212 . In some embodiments, the base plate assembly  208  includes a plurality of electrical feedthroughs  214  coupled to a base plate  216  and extending through openings in the base plate  216 . 
     The cooling plate  212  includes a plurality of openings  218  aligned with the plurality of electrical feedthroughs  214 . In some embodiments, the plurality of openings  218  are disposed in a central region of the cooling plate  212 . In some embodiments, the central region includes a central protrusion  230  extending from a lower surface of the cooling plate  212 . In some embodiments, the plurality of electrical feedthroughs  214  are disposed in the central protrusion  230  of the cooling plate  212 . In some embodiments, the central protrusion  230  is disk shaped, and an outer diameter of the central protrusion  230  is substantially similar to an outer diameter of the base plate  216 . 
     The electrostatic chuck  150  is disposed above the upper assembly  210  and removably coupled to the cooling plate  212 . In some embodiments, a terminal  222  extends from a lower surface of the electrostatic chuck  150  opposite and aligned with each of the plurality of electrical feedthroughs  214  to electrically couple each of the electrical feedthroughs  214  to an electronic component disposed in the electrostatic chuck  150  (e.g., chucking electrode  154 , heater elements  508 , or the like). In some embodiments, a flexible connector  228  is disposed in each of the plurality of openings  218  and configured to couple each terminal  222  to each respective one of the plurality of electrical feedthroughs  214 . The flexible connector  228  is configured to maintain electrical connection between the terminals  222  and plurality of electrical feedthrough  214  during thermal expansion and/or contraction between the upper assembly  210  and the electrostatic chuck  150 . The flexible connector  228  may include a first end  830  (see  FIG.  8   ) having a first opening facing the electrostatic chuck  150  to receive one of the terminals  222  and a second end  832  having a second opening at a second end facing the base plate  216  to receive a conductive core of one of the plurality of electrical feedthroughs  214 . 
     In some embodiments, the electrostatic chuck  150  includes five terminals  222  and the base plate assembly  208  includes five of the plurality of electrical feedthroughs  214 , two, or a first pair, for electrically coupling the one or more chucking electrodes  154 , two, or a second pair, for a single zone heater, and one for a center tap configured to measure a floating voltage of the substrate  122  when a voltage is applied, for example, when bias voltage or voltage from the RF power source and to the ACT is applied. In some embodiments, the electrostatic chuck  150  includes seven terminals  222 , two for the one or more chucking electrodes  154 , four for a two-zone heater, and one for a center tap. The electrostatic chuck  150  and the upper assembly  210  may be configured to accommodate more or less than five to seven terminals  222 . In some embodiments, a central region  232  of the electrostatic chuck  150  includes an interface ring  236  extending from a lower surface thereof. The terminals  222  may be disposed radially outward about the interface ring  236 . In some embodiments, the terminals  222  extend into respective ones of the plurality of openings  218  in the cooling plate  212 . 
       FIG.  5    depicts a cross-sectional side view of a closeup of an upper portion  500  of a substrate support  124  in accordance with at least some embodiments of the present disclosure. One or more heater elements  508  may be disposed in the electrostatic chuck  150  to heat the electrostatic chuck  150  along one or more heating zones. The one or more heater elements  508  are coupled to the heater power supply  160 . In some embodiments, a gap  510  is disposed between the electrostatic chuck  150  and the cooling plate  212  to advantageously minimize heat transfer between the electrostatic chuck  150  and the cooling plate  212 . 
     In use, the gap  510  is pumped down via, for example, the vacuum system  184  to create a vacuum gap. The gap  510  is sized large enough to minimize contact heat transfer while small enough to allow RF coupling from the cooling plate  212  to the electrostatic chuck  150  through the gap  510 . In some embodiments, the gap  510  is about 0.002 to about 0.006 inches. In some embodiments, the cooling plate  212  includes a plurality of minimum contact area (MCA) pads  506  to support the electrostatic chuck  150 . In some embodiments, the plurality of MCA pads  506  comprise about 5 to about 15 MCA pads. In some embodiments, the MCA pads  506  are arranged along two or more concentric circles. For example, in some embodiments, the MCA pads  506  comprise 3 pads along an inner concentric circle and 6 pads along an outer concentric circle. In some embodiments, the MCA pads  506  are arranged along regular intervals. In some embodiments, at least some of the MCA pads  506  are aligned along a common radius of the cooling plate  212 . 
       FIG.  6    depicts an interface between an electrostatic chuck  150  and a cooling plate  212  in accordance with at least some embodiments of the present disclosure. The electrostatic chuck  150  is removably coupled from the cooling plate  212  for enhanced replaceability and ease of cleaning. In some embodiments, the electrostatic chuck  150  is coupled to the cooling plate  212  at a central region  232  of the electrostatic chuck  150  such that a lower surface  512  of the electrostatic chuck  150  is spaced from an upper surface  518  of the cooling plate  212 . In some embodiments, the electrostatic chuck  150  is coupled to the cooling plate  212  via a fastener  602  that extends through a central through hole  632  of the central region  232  of the electrostatic chuck  150  and into the cooling plate  212 . In some embodiments, the central through hole  632  includes a ledge  634  for supporting a head of the fastener  602 . 
     In some embodiments, the fastener  602  secures the electrostatic chuck  150  to the cooling plate  212 . In some embodiments, the cooling plate  212  includes a cavity  608  formed in a bottom surface of the central recess  314 . In some embodiments, a nut plate  606  is disposed in the cavity  608 . In some embodiments, the fastener  602  extends through the nut plate  606  and outer threads of the fastener  602  engage with a threaded opening  610  in the cooling plate  212  to couple the electrostatic chuck  150  to the cooling plate  212 . 
     For detaching the electrostatic chuck  150  from the cooling plate  212 , the fastener  602  may be removed. For disengaging the electrical contacts between the electrostatic chuck  150  and the base plate assembly  208 , in some embodiments, the nut plate  606  includes inner threads  612  that engages outer threads of a tool (not shown) for lifting up the nut plate  606 . When the nut plate  606  is lifted, the nut plate  606  pushes against the electrostatic chuck  150  and disengages all of the electrical contacts. In some embodiments, when the cooling plate  212  includes MCA pads  506 , the interface ring  236  of the electrostatic chuck  150  may be spaced from walls of the central recess  314  and the nut plate  606 . In some embodiments, when the cooling plate  212  does not include MCA pads  506 , the nut plate  606  may provide the only contact region between the electrostatic chuck  150  and the cooling plate  212 , advantageously minimizing thermal coupling. In some embodiments, the nut plate  606  may contact the interface ring  236  to support the central region  232  of the electrostatic chuck  150  and the MCA pads  506  may support a peripheral region of the electrostatic chuck  150 . 
     In some embodiments, the central through hole  632  is coupled to the gas conduit  146  for supplying backside gas from the backside gas supply  141  to an upper surface of the electrostatic chuck  150 . In some embodiments, the fastener  602  includes a gas passageway  638  disposed therethrough to provide a flow path for the backside gas to the upper surface of the electrostatic chuck  150 . A gas plug (not shown) may be disposed in the central through hole  632  above the fastener  602 . 
       FIG.  7 A  depicts a backside metallization pattern on a backside of an electrostatic chuck  150  in accordance with at least some embodiments of the present disclosure.  FIG.  7 B  depicts a schematic side view of an electrostatic chuck  150  with a backside metallization pattern in accordance with at least some embodiments of the present disclosure. In some embodiments, RF is coupled from the cooling plate  212  to the electrostatic chuck  150  via a backside metallization  702  of the electrostatic chuck  150  that is physically in contact with the cooling plate  212  to provide RF coupling. The backside metallization  702  may eliminate need for the gap  510  and may improve RF delivery. The backside metallization  702  may comprise any suitable metal for RF coupling. 
     In some embodiments, one or more RF contacts  720  may be disposed between the backside metallization  702  and the cooling plate  212  so that an RF delivery path extends from the one or more RF contacts  720  to the backside metallization  702  and the backside metallization  702  is not fully in contact with the cooling plate  212 , reducing thermal coupling. In some embodiments, the one or more RF contacts are disposed along a ring  710 . The backside metallization  702  may comprise any suitable pattern disposed on the lower surface  512  of the electrostatic chuck  150 . For example, the backside metallization  702  may comprise a plurality of branches  718  extending from a central region  232  to an outer region  730  or outer surface  732  of the electrostatic chuck  150 . In some embodiments, the plurality of branches  718  extend in a non-linear manner. In some embodiments, a second plurality of branches  728  are disposed between the plurality of branches  718  in the outer region  730 . In some embodiments, there is one of the one or more RF contacts  720  for each plurality of branches  718  and each second plurality of branches  728 . 
     Returning back to  FIG.  2   , the support assembly  103  includes an inner tube  112  coupled to the cooling plate  212  and configured to provide an RF delivery path to the electrostatic chuck  150  via at least one of: the gap  510  between the electrostatic chuck  150  and the cooling plate  212  or the backside metallization  702  of the electrostatic chuck  150 . The gas conduit  146  extends through the inner tube  112 . In some embodiments, the backside gas supply  141  is fluidly coupled to the lower surface  512  of the electrostatic chuck  150  via the gas conduit  146  of the base plate assembly  208 , a gas opening  268  through the cooling plate  212 , and the central through hole  632  of the electrostatic chuck  150 . In some embodiments, a temperature measurement device  266  extends through the inner tube  112 . In some embodiments, the temperature measurement device  266  extends through the base plate  216  and through the cooling plate  212  into the electrostatic chuck  150 . In some embodiments, the temperature measurement device  266  extends into the interface ring  236  of the electrostatic chuck  150 . In some embodiments, the temperature measurement device  266  extends through the central protrusion  230  of the cooling plate  212 . The temperature measurement device  266  may be a thermocouple, an optic temperature measurement device, or the like. 
     In some embodiments, the lower assembly  220  of the pedestal  136  includes a ceramic block  224  disposed on a housing  226  of the lower assembly  220 . In some embodiments, the housing  226  includes an outer lip  246  that surrounds the ceramic block  224 . In some embodiments, the housing  226  includes an outer ledge  248  that extends radially outward from the outer lip  246 . The outer ledge  248  may provide a coupling surface for the plurality of ground loops  172 . The housing  226  is coupled to the outer tube  114 . In some embodiments, the housing  226  is disposed on a bellows weldment  258  that is coupled to the bellows assembly  110 . 
     In some embodiments, the cooling plate  212  includes coolant channel  240  for circulating a cooling therein to control a temperature of the electrostatic chuck  150 . A coolant supply line  242  may extend from a coolant supply  280  to the coolant channel  240 . In some embodiments, the coolant supply line  242  extends through the inner tube  112 . The cooling plate  212  is discussed in more detail below with respect to  FIGS.  3  and  4   . 
     In some embodiments, the lower assembly  220  of the pedestal  136  includes an RF delivery tray  250  coupled to the inner tube  112  at a lower end and to the cooling plate  212  at an upper end. In some embodiments, the RF delivery tray  250  has a bowl-like shape extends from the inner tube  112  to proximate the ceramic block  224 . In some embodiments, the base plate  216  and the central protrusion  230  of the cooling plate  212  may be disposed within the RF delivery tray  250 . In some embodiments, the RF delivery tray  250  includes and outer lip  252  that extends radially outward from an upper portion of the RF delivery tray  250 . In some embodiments, the outer lip  252  is disposed between the cooling plate  212  and the ceramic block  224 . In some embodiments, the lower assembly  220  includes a cover plate  254  coupled to the base plate  216  within the RF delivery tray  250  and configured to cover the plurality of electrical feedthroughs  214 . In some embodiments, the cover plate  254  is made of a polymer material. 
     In some embodiments, an RF delivery path extends from the inner tube  112  to the RF delivery tray  250  to outer surfaces of the cooling plate  212  to the upper surface  518  of the cooling plate  212  and to the electrostatic chuck  150 . In some embodiments, an RF return path extends from the processing volume  119  to upper surfaces of the housing  226  to the outer tube  114 . The ceramic block  224  is configured to electrically isolate the RF delivery path and the RF return path. In some embodiments, the housing  226  is made of a metal, such as aluminum. In some embodiments, the inner tube  112  is made of metal, such as aluminum. 
       FIG.  3    depicts an isometric top view of a cooling plate  212  in accordance with at least some embodiments of the present disclosure. In some embodiments, the cooling plate  212  is made of stainless steel or aluminum. In some embodiments, the upper surface  518  of the cooling plate  212  has varying emissivity as desired to control heat loss. For example, the upper surface  518  may have higher emissivity at a central portion  310  than at a peripheral portion  320  to further aid in controlling temperature uniformity across the electrostatic chuck  150 . The higher emissivity may be achieved via any suitable process, for example, by machining, gritting, anodizing, or the like. 
     The cooling plate  212  may include a plurality of radially channels  304  on the upper surface  518  thereof to aid in evacuating air disposed between the cooling plate  212  and the electrostatic chuck  150  to create a vacuum therebetween. In some embodiments, the upper surface  518  includes a central recess  314  to accommodate the interface ring  236  of the electrostatic chuck  150 . In some embodiments, one radial channel  304 A of the plurality of radial channels  304  may extend into the central recess  314  to aid in evacuating air disposed between the interface ring  236  and the cooling plate  212 . In some embodiments, the plurality of radial channels  304  comprise six channels. In some embodiments, the plurality of radial channels  304  extend through the openings  218  for the plurality of electrical feedthroughs  214 . The cooling plate  212  may include openings  306  to accommodate the lift pins  109 . 
       FIG.  4    depicts an isometric bottom view of a cooling plate  212  in accordance with at least some embodiments of the present disclosure. In some embodiments, a lower surface  402  of the cooling plate  212  includes the central protrusion  230  and the coolant channel  240  disposed about the central protrusion  230 . The coolant channel  240  may extend along any suitable path for cooling the cooling plate  212 . In some embodiments, the coolant channel  240  extends in a wavy or non-circular manner. In some embodiments, the coolant channel  240  includes an inlet  420  and an outlet  422 . In some embodiments, the cooling plate  212  includes one or more alignment features  412  for aligning the cooling plate  212  with the base plate  216 . In some embodiments, the central protrusion  230  includes an opening  406  for the temperature measurement device  266 . In some embodiments, the gas opening  268  through the cooling plate  212  may include one or more bends to provide adequate separation between the gas opening  268  and the temperature measurement device  266 . An o-ring groove  430  may be disposed about the gas opening  268  to seal the gas opening  268 . 
       FIG.  8    depicts an isometric top view of the base plate assembly  208  in accordance with at least some embodiments of the present disclosure. In some embodiments, the base plate  216  of the base plate assembly  208  includes a plurality of fastener openings  810  for coupling the base plate  216  to the cooling plate  212 . The base plate  216  includes a gas opening  812  coupled to the gas conduit  146 . The gas opening  812  is aligned with the gas opening  268  of the cooling plate  212 . In some embodiments, the plurality of electrical feedthroughs  214  may be disposed proximate an outer surface of the base plate  216 . An o-ring groove  818  may be disposed about each of the plurality of electrical feedthroughs  214  to seal the plurality of openings  218  of the cooling plate  212 . An o-ring groove  806  may be disposed about the temperature measurement device  266 .  FIG.  8    depicts one of the flexible connectors  228 . In some embodiments, the flexible connectors  228  include a plurality of slits  834  to allow the first end  830  to move with respect to the second end  832 . 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.