Patent Publication Number: US-2021176831-A1

Title: Gas distribution ceramic heater for deposition chamber

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. provisional patent application Ser. No. 62/944,180, filed Dec. 5, 2019 which is herein incorporated by reference in its entirety. 
    
    
     FIELD 
     Embodiments of the present disclosure generally relate to a substrate processing equipment. 
     BACKGROUND 
     Substrate processing systems generally include a process chamber that forms an enclosure having a support pedestal for supporting a substrate, such as a semiconductor substrate, within the enclosure. In some processes, plasma may be used for deposition or etching of materials in the process chamber. A showerhead may be disposed opposite the support pedestal within the enclosure to distribute one or more process gases therethrough. A heater may be disposed proximate the showerhead to heat the showerhead and form a plasma therebetween. However, the inventors have observed non-uniform deposition or etching of materials when a heater is disposed within the enclosure and one or more process gases are injected from a top of the process chamber. 
     Accordingly, the inventors have provided improved lid heaters for use in the process chamber. 
     SUMMARY 
     Embodiments of a lid heater for a deposition chamber are provided herein. In some embodiments, a lid heater for a deposition chamber includes a ceramic heater body having a first side opposite a second side, wherein the ceramic heater body includes a first plurality of gas channels extending from one or more first gas inlets on the first side, wherein each of the one or more first gas inlets extend to a plurality of first gas outlets on the second side; a heating element embedded in the ceramic heater body; and an RF electrode embedded in the ceramic heater body proximate the second side, wherein the first plurality of gas channels extend through the RF electrode. 
     In some embodiments, a substrate processing apparatus includes a lid heater having a ceramic heater body having a first side opposite a second side, wherein the ceramic heater body includes a first plurality of gas channels extending from one or more first gas inlets on the first side to a plurality of first gas outlets on the second side, wherein the first plurality of gas channels includes a first passageway extending substantially vertically from each of the one or more first gas inlets towards the second side, a plurality second passageways extending radially outward from each first passageway, and a plurality of third passageways extending from each of the plurality of second passageways towards the plurality of first gas outlets; an RF electrode embedded in the ceramic heater body proximate the second side, wherein the first plurality of gas channels extend through the RF electrode; and a heating element embedded in the ceramic heater body. 
     In some embodiments, a deposition chamber includes a process chamber having a chamber lid and defining a processing volume therein; a support pedestal disposed in the processing volume to support a substrate; a lid heater coupled to the chamber lid, wherein the lid heater includes a ceramic heater body having a first side opposite a second side and a heating element embedded therein, wherein the lid heater includes a first plurality of gas channels extending from one or more first gas inlets on the first side, wherein each of the one or more first gas inlets extend to a plurality of first gas outlets on the second side; and an RF electrode embedded in the ceramic heater body proximate the second side, wherein the first plurality of gas channels extend through the RF electrode. 
     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 substrate processing apparatus suitable for a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 2  depicts a schematic side view of a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 3  depicts a schematic side view of a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 4  depicts a schematic side view of a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 5  depicts a schematic cross-sectional bottom view of a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 6  depicts a schematic cross-sectional bottom view of a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 7  depicts a schematic cross-sectional bottom view of a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 8A  depicts a top cross-sectional view of a portion of a lid heater in accordance with some embodiments of the present disclosure. 
         FIG. 8B  depicts a top cross-sectional view of a portion of a lid heater in accordance with 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 lid heaters made of a ceramic material for a deposition chamber are provided herein. Embodiments of lid heaters described herein advantageously include a plurality of gas distribution channels to more uniformly distribute one or more process gases therethrough. An RF electrode is embedded in the lid heater to facilitate plasma formation adjacent the lid heater. 
       FIG. 1  depicts a schematic side view of a substrate processing apparatus  10  suitable for a lid heater in accordance with some embodiments of the present disclosure. In some embodiments, the substrate processing apparatus  10  includes a process chamber  100  having a chamber lid, a gas panel  130 , a control unit  110 , along with other hardware components such as power supplies and vacuum pumps. Exemplary process chambers suitable for modification in accordance with the teachings provided herein include any of several process chambers configured for chemical vapor deposition (CVD) and available from Applied Materials, Inc. of Santa Clara, Calif. Other suitable process chambers from other manufacturers may similarly be used and modified in accordance with the present disclosure. 
     The process chamber  100  generally comprises a lid heater  131 . The lid heater  131  can be used to heat a processing volume  101  including a remote processing volume  144  between the lid heater  131  and a showerhead  165  disposed within the process chamber  100 . Depending on the specific process, the remote processing volume  144  may be heated to some desired temperature prior to and/or during processing in accordance with the present disclosure. In some embodiments, the lid heater  131  is heated by an embedded heating element such as heating element  171 . For example, the lid heater  131  may be resistively heated by applying an electric current from an AC supply  124  to the heating element  171 . The remote processing volume  144  is, in turn, heated by the lid heater  131  and can be maintained within a process temperature range of, for example, 200 to 800 degrees Celsius, or at a first temperature of about 600 degrees Celsius or greater. 
     In some embodiments, a temperature sensor  146 , such as a thermocouple, may be embedded in the lid heater  131  to monitor the temperature of the lid heater  131  in a conventional manner. For example, the measured temperature may be used in a feedback loop to control the power supply for the lid heater  131  such that the temperature of the remote processing volume  144  can be maintained or controlled at a desired temperature that is suitable for a particular process or application. 
     In some embodiments, the lid heater  131  is configured to provide enough heat to promote remote plasma formation in the remote processing volume  144  between the lid heater  131  and the showerhead  165 . In some embodiments, the lid heater  131  is configured to provide enough heat to prevent condensation within or upon the showerhead  165 . For example, a control unit  110  may be in communication with the lid heater  131  so that a user can adjust the heat of the lid heater  131  and maintain a heat sufficient for remote plasma formation. In some embodiments, depending upon processing needs, the lid heater  131  is configured not to heat, or promote remote plasma formation, in the remote processing volume  144 . For example, the lid heater  131  may be switched off via the control unit  110  depending upon user needs. 
     In some embodiments, the process chamber  100  generally includes a support pedestal  150  having a support surface  192 , which is used to support a substrate  190  such as a semiconductor substrate within the process chamber  100 . The support pedestal  150  can be coupled to a hollow support shaft  160  and moved in a vertical direction inside the process chamber  100  using a displacement or lift mechanism (not shown). Depending on the specific process, the substrate  190  may be heated to some desired temperature prior to processing. In some embodiments, the support pedestal  150  is heated by an embedded heating element such as heating element  170 . For example, the support pedestal  150  may be resistively heated by applying an electric current from an AC supply  106  to the heating element  170 . The substrate  190  is, in turn, heated by the support pedestal  150 , and can be maintained within a process temperature range of, for example, 300 to 800 degrees Celsius. In some embodiments, a temperature sensor  172 , such as a thermocouple, may be embedded in the support pedestal  150  to monitor the temperature of the support pedestal  150  in a conventional manner. For example, the measured temperature may be used in a feedback loop to control the power supply such as the AC supply  106  for the heating element  170  such that a temperature of the substrate  190  can be maintained or controlled at a desired temperature that is suitable for the particular process or application. In some embodiments, the support pedestal includes a ground at  182 . 
     In some embodiments, the lid heater  131  can include a radio frequency (RF) electrode  181 , for example, disposed on or embedded in the lid heater  131 . An RF power source  180  can be coupled to the RF electrode  181  to provide RF power to the lid heater  131 . RF power can be provided from the RF power source  180  to the RF electrode  181  in an amount sufficient to form a plasma in the remote processing volume  144  between the lid heater  131  and the showerhead  165 . For example, the control unit  110  may be in communication with the RF power source  180  so that a user can adjust the RF power provided to the lid heater  131  and to maintain RF power provided in an amount sufficient for plasma formation. 
     The processing volume  101  includes a direct processing volume  152  disposed between the showerhead  165  and the support pedestal  150 . In some embodiments, the showerhead  165  includes a second RF electrode  148  for providing RF energy in an amount sufficient to form a plasma in the direct processing volume  152  and/or in the remote processing volume  144 . The second RF electrode  148  can be coupled to the RF power sources  180  or to a second RF power source (not shown). In some embodiments, the second RF electrode  148  may be embedded in the showerhead  165 . In some embodiments, at least a portion of the showerhead  165  may be formed of a conductive material suitable to function as the second RF electrode  148 . In some embodiments, the showerhead  165  includes the second RF electrode  148  and the lid heater  131  includes the RF electrode  181  for providing RF energy to both the lid heater  131  and the showerhead  165  in an amount sufficient to form a plasma in the remote processing volume  144  between the showerhead  165  and the lid heater  131 . In some embodiments, the showerhead  165  may be coupled or selectively coupled to a ground  183  depending upon user needs for plasma placement within the processing volume  101 . 
     The RF electrode  181  and the second RF electrode  148  may be coupled to one or more RF power sources  180  through one or more respective matching networks that can be part of the RF power source or separately provided (separate matching network not shown). The one or more RF power sources  180  may be capable of producing up to 3000 watts of RF energy at a frequency of about 350 kHz to about 60 MHz, such as at about 350 kHz, or about 13.56 MHz, or about 60 Mhz, or the like. In some embodiments, the process chamber  100  may utilize capacitively coupled RF energy for plasma processing. For example, the process chamber  100  may have a ceiling made from dielectric materials and a showerhead  165  that is at least partially conductive to provide the second RF electrode  148  (or a separate RF electrode may be provided). The showerhead  165  (or separate RF electrode) may be coupled to one or more RF power sources  180  through one or more respective matching networks (not shown). The one or more RF power sources  180  may be capable of producing up to about 3,000 watts, or in some embodiments, up to about 5,000 watts, of RF energy at a frequency of about 350 kHz to about 60 MHz, such as at about 350 kHz, or about 13.56 MHz, or about 60 Mhz, or the like. 
     In use, the control unit  110  may be in communication with the RF power sources  180 , or the RF power sources  180  and the second RF power source (not shown) so that a user can adjust RF power provided to at least one of the showerhead  165  and the lid heater  131  to maintain RF power sufficient for plasma formation in at least one of the remote processing volume  144  or the direct processing volume  152 . For example, in some embodiments, a plasma may be formed in the remote processing volume  144  by grounding the showerhead  165  (e.g., coupling the showerhead  165  to the ground  183 ) and providing sufficient RF power to the RF electrode  181  to ignite and/or maintain a plasma in the remote processing volume  144 . In some embodiments, a plasma may be formed in the direct processing volume  152  providing sufficient RF power to the showerhead  165 , and more particularly the second RF electrode  148 , to ignite and/or maintain a plasma in the direct processing volume  152 . In such embodiments, the showerhead  165  is not grounded (e.g., is not coupled to the ground  183 ). 
     In some embodiments, proper control and regulation of gas flows through the process chamber  100  and gas panel  130  is performed by mass flow controllers (not shown) and the controller unit  110 . The showerhead  165  allows process gases from the gas panel  130  to be uniformly distributed and introduced into the process chamber  100 . In some embodiments, the showerhead  165  is configured for flowing reaction products (such as reaction products suitable for forming a titanium material layer as described herein) into the process chamber to selectively form a desired material layer, such as a titanium material layer, upon a surface, such as a silicon surface, of the substrate. 
     Illustratively, the control unit  110  includes a central processing unit (CPU)  112 , support circuitry  114 , and memory  116  containing associated control software. The control unit  110  is responsible for automated control for processing the substrate  190  such as substrate transport, gas flow control, temperature control, chamber evacuation, and so on. Bidirectional or unidirectional communication between the control unit  110  and the various components of the substrate processing apparatus  10  are handled through numerous signal cables collectively referred to as signal buses  118 , some of which are illustrated in  FIG. 1 . 
     In some embodiments, the process chamber  100  includes a vacuum pump  102  to evacuate the process chamber  100  and to maintain the proper gas flows and pressure inside the process chamber  100 . The showerhead  165 , through which process gases are introduced into the process chamber  100 , is located above the support pedestal  150 . In some embodiments, the showerhead  165  may be configured as a multiple gas showerhead having two or more separate pathways, which allow two or more gases to be separately introduced into the processing chamber  100  without premixing. In some embodiments, the showerhead  165  is connected to the gas panel  130  which controls and supplies, through mass flow controllers (not shown), various gases used in different steps of the process sequence. During substrate processing, a purge gas supply  104  also provides a purge gas, for example, an inert gas, around the bottom of the support pedestal  150  to minimize undesirable deposits from forming on the support pedestal  150 . 
     A first gas flow line  162  is coupled to the lid heater  131  and is configured to provide gas flow from the gas panel  130  to the lid heater  131 . The gas provided to the lid heater  131  from the first gas flow line  162  advantageously flows through the lid heater  131 , as described in more detail below, and provides a more uniform gas flow to the direct processing volume  152  through first gas distribution openings  156  in the showerhead  165  that pass completely through the showerhead  165 . In some embodiments, a second gas flow line  163  is coupled to the showerhead  165  and is configured to provide a second gas flow from the gas panel  130  to the direct processing volume  152  via internal passageways  154  of the showerhead  165  that are advantageously fluidly independent from the first gas distribution openings  156  in the showerhead  165  and that extend to a substrate-facing side of the showerhead  165 . 
     In some embodiments, the control unit  110  is responsible for controlling gas flow from gas panel  130  to the remote processing volume  144  by the first gas flow line  162 , or within the showerhead  165  by the second gas flow line  163 . In some embodiments, process chamber  100  is configured such that the gas panel  130  provides titanium tetrachloride (TiCl 4 ), hydrogen (H 2 ) and/or argon (Ar) inside process chamber  100  and processing volume  101 . In some embodiments, one or more desired gases may be directed from the gas panel  130  into the direct processing volume  152  through the showerhead  165  via the second gas flow line  163 . For example, in some embodiments, one or more of silane such as SiH 4 , disilane such as Si 2 H 6 , hydrogen (H 2 ), or argon (Ar) gases may be added to processing volume  101  by the second gas flow line  163 . 
     In some embodiments, such as where the processing chamber  100  is configured for remote plasma application, e.g., igniting plasma in the remote processing volume  144 , or within showerhead  165 , one or more desired gases such as titanium tetrachloride (TiCl 4 ), hydrogen (H 2 ) and/or argon (Ar) may be directed from gas panel  130  into processing volume  101  via the first gas flow line  162 , and one or more desired gases such as silane such as SiH 4 , or hydrogen (H 2 ), or argon (Ar) gases may be directed to processing volume  101  by the second gas flow line  163 . In some embodiments, the flow rate, temperature, and pressure of the processing volume can be adjusted to values sufficient for a reaction desired in accordance with the present disclosure. 
     In some embodiments, such as where processing chamber  100  is configured for direct plasma application, e.g., igniting plasma in the direct processing volume  152  one or more desired gases such as nitrogen (N 2 ), hydrogen (H 2 ) or argon (Ar) may be directed from the gas panel  130  into the processing volume  101  via the first gas flow line  162 , and one or more desired gases such as argon (Ar) may be directed to processing volume  101  by the second gas flow line  163 . In some embodiments, the flow rate, temperature, and pressure of the processing volume can be adjusted to values sufficient for a reaction desired in accordance with the present disclosure. 
       FIGS. 2 and 3  depict schematic side views of a lid heater  131  in accordance with some embodiments of the present disclosure. The lid heater  131  includes a heater body  210  made of a ceramic material. In some embodiments, the heater body  210  is made of aluminum nitride (AlN) or aluminum oxide (Al 2 O 3 ). The heater body  210  includes a first side  208  opposite a second side  202 . The heater body  210  may be a singular body or may comprise a plurality of plates having channels to define a plurality of gas distribution channels when bonded or coupled together. 
     In some embodiments, the plurality of gas distribution channels include a first plurality of gas channels  212  extending from one or more first gas inlets  204  on the first side  208 . Each of the one or more first gas inlets  204  extend to a plurality of first gas outlets  206  on the second side  202 . In the illustrative embodiment of  FIG. 2 , the one or more first gas inlets  204  comprise two first gas inlets. Any embodiments of the lid heater  131  disclosed herein may have one, two, or more first gas inlets  204 . In some embodiments, as shown in  FIG. 2 , the first gas flow line  162  comprises two or more lines that are fluidly coupled to two or more corresponding gas inlets of the one or more first gas inlets  204 . In some embodiments, two or more first gas inlets  204  advantageously enhance gas distribution from the first gas flow line  162  through the first plurality of gas channels  212 . In some embodiments, the first gas outlets  206  have a diameter of about 0.02 inches to about 0.10 inches. 
     The first plurality of gas channels  212  are advantageously configured to dispense a gas flow from a gas source (e.g., gas panel  130 ) to adjacent the second side  202  of the lid heater  131  in a uniform manner. In some embodiments, the first plurality of gas channels  212  have a recursive flow path having a substantially equal flow path length from each of the one or more first gas inlets  204  to multiple ones of the plurality of first gas outlets  206 . In some embodiments, the first plurality of gas channels  212  define a recursive flow path having a substantially equal conductance from the one or more first gas inlet  204  to multiple ones of the plurality of first gas outlets  206 . 
     In some embodiments, the first plurality of gas channels  212  includes a first passageway  216  that extends from each of the one or more first gas inlets  204  towards the second side  202 . In some embodiments, the first passageway  216  extends substantially vertically. The first plurality of gas channels  212  includes a plurality of second passageways  220  extending radially outward from each first passageway  216 . A plurality of third passageways  224  extend from each of the plurality of second passageways  220  towards the second side  202  of the lid heater  131 . In some embodiments, the plurality of third passageways  224  extend from each of the second passageways  220  to the plurality of first gas outlets  206 . In some embodiments, the plurality of third passageways  224  have a cross-sectional area that is less than a cross-sectional area of the plurality of second passageways  220 . 
     In some embodiments, the first plurality of gas channels  212  have a circular cross-section. In some embodiments, the first plurality of gas channels  212  have a circular cross-section having a diameter of about 2.0 mm to about 12.0 mm. In some embodiments, the first plurality of gas channels  212  have a rectangular cross-section. In some embodiments, the first plurality of gas channels  212  have a rectangular cross-section having a width of about 2.0 mm to about 12.0 mm. 
     In some embodiments, the first plurality of gas channels  212  include a plurality of fourth passageways  228  that extend horizontally outward from each of the plurality of third passageways  224 , and a plurality of fifth passageways  230  that extend substantially vertically from each of the plurality of fourth passageways  228  towards the second side  202  of the lid heater  131 . In some embodiments, the plurality of fifth passageways  230  extend to the plurality of first gas outlets  206 . In some embodiments, as shown in  FIG. 2 , a plurality of sixth passageways  232  extend horizontally outward from each of the plurality of fifth passageways  230 , and a plurality of seventh passageways  234  extend vertically from each of the sixth passageways  232  to the plurality of first gas outlets  206 . In some embodiments, as shown in  FIG. 3 , the plurality of third passageways  224  extend substantially vertically from each of the plurality of second passageways  220  to the plurality of first gas outlets  206   
     An RF electrode  214  is embedded in the heater body  210 . The RF electrode  214  is the RF electrode  181  described above with respect to  FIG. 1 . The first plurality of gas channels  212  extend through the RF electrode  214 . In some embodiments, the RF electrode  214  comprises a conductive plate with openings through which the first plurality of gas channels  212  extend. In some embodiments, the RF electrode  214  comprises a conductive mesh through which the first plurality of gas channels  212  extend. In some embodiments, the RF electrode  214  is disposed proximate the second side  202 , for example about 0.5 mm to about 1.5 mm from the second side  202 , to facilitate forming a plasma adjacent the second side  202 . 
     A heating element  218  is embedded in the heater body  210 . In some embodiments, the heating element  218  is the heating element  171  of  FIG. 1 . The heating element  218  is generally disposed between the RF electrode  214  and the first side  208 . In some embodiments, the heating element  218  is approximately centrally located between the first side  208  and the second side  202  to uniformly heat the heater body  210 . In some embodiments, the heating element  218  is disposed in an upper half of the heater body  210  so that the heating element  218  does not interfere with the first plurality of gas channels  212 . In some embodiments, the first passageway  216  extends through the heating element  218 . In some embodiments, the heating element  218  is disposed between the plurality of second passageways  220  and the first side  208 . 
       FIG. 4  depicts a schematic side view of a lid heater  131  in accordance with some embodiments of the present disclosure. In some embodiments, the lid heater  131  is configured to flow two or more process gases (e.g., from gas panel  130 ) therethrough without mixing. In some embodiments, the lid heater  131  includes a second plurality of gas channels  412  that are fluidly independent of the first plurality of gas channels  212 . In some embodiments, the heater body  210  includes a second plurality of gas channels  412  extending from one or more second gas inlets  404  (only one shown in  FIG. 4 ) on the first side  208  to a plurality of second gas outlets  406  on the second side  202 . In some embodiments, the second plurality of gas channels  412  extend through the RF electrode  214 . 
     In some embodiments, the plurality of second gas outlets  406  are disposed radially inward of the plurality of first gas outlets  206 . In some embodiments, the plurality of second gas outlets  406  are disposed radially outward of the plurality of first gas outlets  206 . In some embodiments, the plurality of second gas outlets  406  and the plurality of first gas outlets  206  are arranged in an alternating pattern from a center of the heater body  210  to an outer sidewall of the heater body  210 . In some embodiments, the second plurality of gas channels  412  have a cross-sectional size and shape similar to those discussed above with respect to the first plurality of gas channels  212 . In some embodiments, the second plurality of gas channels  412  have a cross-sectional area that is similar to a cross-sectional area of the first plurality of gas channels  212 . In some embodiments, the second plurality of gas channels  412  have a cross-sectional area that is smaller than the cross-sectional area of the first plurality of gas channels  212 . In some embodiments, the second plurality of gas channels  412  have a cross-sectional area that is larger than the cross-sectional area of the first plurality of gas channels  212 . 
     In some embodiments, the second plurality of gas channels  412  includes a first passageway  416  that extends from each of the one or more second gas inlets  404  towards the second side  202 . In some embodiments, the first passageway  416  extends substantially vertically. The second plurality of gas channels  412  includes a plurality of second passageways  420  extending radially outward from each first passageway  416 . A plurality of third passageways  422  extend from each of the second passageways  420  towards the plurality of second gas outlets  406 . In some embodiments, as shown in  FIG. 4 , the plurality of third passageways  422  extend substantially vertically from each of the second passageways  420  to the second side  202 . In some embodiments, the second plurality of gas channels  412  extend from each of the plurality of third passageways  422  in a manner similar to the plurality of third passageways  224  of the first plurality of gas channels  212  as shown and described with respect to  FIG. 2 . 
       FIG. 5  depicts a schematic cross-sectional bottom view of a lid heater in accordance with some embodiments of the present disclosure. In some embodiments, radially extending passageways of the heater body  210 , for example, the second passageways  220 , the fourth passageways  228 , or the sixth passageways  232  define internal conduits  502 . In some embodiments, the internal conduits  502  are proximate the second side  202 . In some embodiments, proximate means closer to the second side  202  than the first side  208 . The plurality of first gas outlets  206  are fluidly coupled to the internal conduits  502  via, for example, the third passageway  224  or the seventh passageway  234 . The internal conduits  502  are configured to further direct gas flow from vertical extending passageways of the heater body  210 , for example, the first passageway  216 , the third passageways  224 , the fifth passageways  230 , to the plurality of first gas outlets  206  across the heater body  210 . The internal conduits  502  may be formed via any suitable manufacturing process, for example, machining or lamination. 
     As shown in  FIG. 5 , the internal conduits  502  include an annular groove  506  proximate a center of the heater body  210 . A plurality of branches extend radially outward form the annular groove  506 . In some embodiments, the plurality of branches include a plurality of first branches  508  extending radially outward form the annular groove  506 . In some embodiments, the plurality of first branches  508  are four branches. In some embodiments, the plurality of first branches  508  are of equal length. In some embodiments, the plurality of first branches  508  are four branches of equal length. In some embodiments, a plurality of second branches  510  extend radially outward from each of the plurality of first branches  508 . In some embodiments, the plurality of second branches  510  are two branches. In some embodiments, the plurality of second branches  510  are of equal length. In some embodiments, the plurality of second branches  510  are two branches of equal length. In some embodiments, a plurality of third branches  512  extend radially outward from each of the plurality of second branches  510 . In some embodiments, the plurality of third branches  512  are two branches. In some embodiments, the plurality of third branches  512  are of equal length. In some embodiments, the plurality of third branches  512  are two branches of equal length. In some embodiments, a plurality of fourth branches  514  extend radially outward from each of the plurality of third branches  512 . In some embodiments, the plurality of fourth branches  514  are two branches. In some embodiments, the plurality of fourth branches  514  are of equal length. In some embodiments, the plurality of fourth branches  514  are two branches of equal length. 
       FIG. 6  depicts a schematic cross-sectional bottom view of a lid heater in accordance with some embodiments of the present disclosure. As shown in  FIG. 6 , the internal conduits  502  include an annular groove  602  proximate a center of the heater body  210 . In some embodiments, the internal conduits  502  include a plurality of concentric grooves  604  disposed radially outward of the annular groove  602 . In some embodiments, the internal conduits  502  include a plurality of radial grooves  608  extending between two or more of the plurality of concentric grooves  604 . In some embodiments, at least some of the plurality of radial grooves  608  extend between the annular groove  602  and the plurality of concentric grooves  604 . 
       FIG. 7  depicts a schematic cross-sectional bottom view of a lid heater in accordance with some embodiments of the present disclosure. In some embodiments, the internal conduits  502  include an annular groove  702  proximate a center of the heater body  210 . In some embodiments, the internal conduits  502  are arranged in an orthogonal pattern about the annular groove  702 . For example, the internal conduits  502  include a plurality of first grooves  704  that are substantially parallel to each other. In some embodiments, the internal conduits  502  include a plurality of second grooves  706  that are substantially parallel to each other and substantially perpendicular to the plurality of first grooves  704 . In some embodiments, the plurality of first grooves  704  are disposed at regular intervals across the heater body  210 . In some embodiments, the plurality of second grooves  706  are disposed at regular intervals across the heater body  210 . 
       FIG. 8A  and  FIG. 8B  depict top cross-sectional views of a portion of a lid heater in accordance with some embodiments of the present disclosure. In some embodiments, the plurality of first grooves  704  and the plurality of second grooves  706  are defined by a plurality of posts. In some embodiments, as shown in  FIG. 8A , a plurality of posts  820  have a circular cross-section. The plurality of posts may have any suitable cross-sectional shape. In some embodiments, as shown in  FIG. 8B , a plurality of posts  810  have a rectangular, or square, cross-section. 
     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.