Friction Stir Welding in Semiconductor Manufacturing Applications

Abstract

In one example, a showerhead base assembly for a substrate processing chamber is provided. The showerhead base assembly includes a panel. A platform is disposed within the panel and includes a heater element extending through at least one groove within the panel. The at least one groove is contoured to receive at least a portion of the heater element. A peripheral edge of the platform is joined to an inner surface of the panel by a friction stir welded joint.

Description

[0001] Priority claim

[0002] This application claims the benefit of priority to U.S. patent application Ser. No. 62 / 819,215, filed Mar. 15, 2019, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to friction stir welding in semiconductor manufacturing applications, and more particularly to forming friction stir welded components that can efficiently transfer heat during the manufacture of semiconductor devices. In an exemplary particular aspect, the present disclosure relates to using friction stir welding to join components together in a pedestal for a processing chamber, more particularly, a showerhead pedestal. Background Art

[0004] The background description provided here is for the purpose of generally presenting the context of the present disclosure. No admission is made, either explicitly or implicitly, that the work of the presently designated inventors is prior art to the present disclosure to the extent that it is described in this background section and in aspects of the specification that were not determined to be prior art at the time the application was filed.

[0005] In some conventional semiconductor manufacturing applications, heater coils are embedded in the platform channels of a susceptor and filled with metal plugs that are electron beam (e-beam) welded or vacuum brazed into place. In such cases, the interface bond strength between the heater coils and the susceptor components has proven inconsistent and poor, resulting in inefficient heat transfer between the heater coils and the susceptor plate and sometimes causing susceptor warping and premature failure. Summary of the Invention

[0006] In some embodiments, friction stir welding of heater coils is used to address the limitations of conventional welding techniques and to avoid base warping and premature failure thereof. In some embodiments, attempts are also made to provide improved thermal performance of the base by using hot rods or tubes and cascaded circular baffles.

[0007] In some examples, a showerhead pedestal assembly for a substrate processing chamber is provided. An exemplary showerhead pedestal assembly includes: a faceplate; a platform disposed in the faceplate, the platform including a heater element extending through at least one groove in the faceplate, the at least one groove being contoured to receive at least a portion of the heater element, the at least a portion of the heater element extending through the at least one groove; and a power source for the heater element, wherein a peripheral edge of the platform is joined to an inner surface of the faceplate by a friction stir welded joint.

[0008] In some examples, the faceplate includes a plurality of apertures to enable gas to pass through the showerhead pedestal assembly to an underside of a substrate supported by the showerhead pedestal assembly.

[0009] In some examples, the showerhead base assembly further includes a plurality of heat transfer rods extending between the faceplate and the opposing surface of the platform, the plurality of heat transfer rods comprising a friction stir welding material.

[0010] In some examples, the friction stir welding material is different from a material of the faceplate or the platform and is capable of forming a friction stir welded joint between the faceplate and the platform.

[0011] In some examples, the material of the plurality of heat transfer rods is selected to enhance or hinder heat transfer between the panel and the platform.

[0012] In some examples, the plurality of heat transfer rods are formed from the same material as the heater element.

[0013] In some examples, the showerhead base assembly further includes a fill cap including at least one baffle sized and configured to reside in the at least one groove in the faceplate.

[0014] In some examples, the at least one baffle of the filler cap secures the at least a portion of the heater element within a corresponding groove in the panel.

[0015] In some examples, the at least one baffle includes a curved structure that matches a profile of the corresponding groove in the panel.

[0016] In some examples, the at least one baffle comprises a friction stir weld material.

[0017] In some examples, the at least one baffle is provided along an upper surface of the fill cap.

[0018] In some examples, a portion of the fill cap includes a heat sink that provides a body of material that is relatively cooler than a material of the platform during operation of the showerhead base assembly.

[0019] In some examples, the at least one baffle includes at least one aperture to enable gas to pass through the at least one aperture.

[0020] In some examples, the at least one baffle is provided in a series of baffles extending in a spaced array along the contour of the heater element, the spaced array of baffles including one or more gaps between consecutive baffles to enable gas to pass through the one or more gaps.

[0021] In some examples, the friction stir weld material of the at least one baffle is different than a material of the faceplate or the heater element and is capable of forming a friction stir welded joint between the heater element and the faceplate.

[0022] In some examples, the at least one baffle is included in a plurality of concentric rings of baffles.

[0023] In some examples, at least one of the plurality of concentric rings of baffles includes baffles having a gap.

[0024] In some examples, each of the spaced apart baffles includes one or more apertures formed therein to enable a specific or controlled airflow through the one or more apertures.

[0025] In some examples, the gaps between pairs of spaced apart baffles in the at least one concentric ring of baffles are sized to enable a specific or controlled airflow through the gaps.

[0026] In some examples, the heater element is powered by the power source during formation of the friction stir welded joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Some embodiments are shown by way of example and not limitation in the figures of the accompanying drawings:

[0028] Figure 1 is a cross-sectional view of a showerhead base according to an exemplary embodiment.

[0029] Figure 2 is a configuration for friction stir welding depicted in accordance with an exemplary embodiment.

[0030] Figure 3 is a schematic diagram of a heater element according to an exemplary embodiment.

[0031] Figure 4 is a cross-sectional view of a showerhead base according to an exemplary embodiment.

[0032] Figure 5 is a schematic diagram of a filling cap according to an exemplary embodiment.

[0033] Figure 6 is a cross-sectional view of a showerhead base according to an exemplary embodiment.

[0034] Figure 7 is a partially schematic cross-sectional view of a showerhead base according to an exemplary embodiment.

[0035] Figure 8is a cross-sectional view of a showerhead base according to an exemplary embodiment.

[0036] Figure 9 is a block diagram illustrating an example of a machine by which one or more example embodiments may be controlled.

[0037] Figure 10 1 and 2 show aspects of a configuration for friction stir welding according to an exemplary embodiment.

[0038] Figure 11 is a flowchart of operations included in an exemplary method, according to an exemplary embodiment. DETAILED DESCRIPTION

[0039] The following description contains systems, methods, techniques, instruction sequences, and computer program products for implementing illustrative embodiments of the present disclosure. In the following description, for illustrative purposes, numerous specific details are described to provide a complete understanding of the exemplary embodiments. However, it will be apparent to those skilled in the art that the present embodiments may be practiced without these specific details.

[0040] A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to any data described below and in the drawings that constitute a part of this document: Copyright Lam Research Corporation, 2019-2020, All rights reserved.

[0041] Many semiconductor manufacturing applications include the use of substrate processing chambers. The processing chamber may include a susceptor or a truck to secure the substrate (e.g., a wafer) during processing. As described above, the heater coils used in such susceptors are typically manufactured using conventional techniques such as vacuum brazing or electron beam welding. The interface joint strength between the heater coil and the susceptor component has been shown to be inconsistent and poor, resulting in inefficient heat transfer between the heater and the susceptor plate, and sometimes causing susceptor warping and premature failure of the susceptor.

[0042] For example, in some examples herein, friction stir welding (FSW) is used to manufacture or join susceptor components, such as heater elements, panels, and susceptor main rods. The manufacture or joining of other components is feasible. The manufacturing methods and manufactured products described herein can exhibit improved thermal and mechanical properties compared to products made using conventional techniques such as vacuum brazing and electron beam welding. FSW solves many limitations in conventional techniques. Such limitations may include weld cracking and porosity, resulting in reduced heat transfer within the susceptor component and reduced efficiency of the processing chamber in which such a susceptor is installed.

[0043] refer to Figure 1 , an exemplary showerhead pedestal assembly 100 includes a faceplate 102, and a platform 104 disposed in the faceplate 102. In some examples, the faceplate 102 includes apertures as shown to allow gas to pass upward through the showerhead pedestal assembly 100 to the underside of a substrate (e.g., a wafer) supported by the showerhead pedestal assembly 100 during use.

[0044] The platform 104 distributes heat within the showerhead base assembly 100. The platform 104 includes a heater element 106. The outline and overall construction of an exemplary heater element 106 can be more clearly seen in the following images: Figure 3 Example 300 or Figure 7 As shown in the figure, the heater element 106 includes a plurality of heater coils 108 located in a common plane in a channel (recess, or groove) 124 formed in the platform 104. Other coil configurations are possible. The heater coils 108 are secured in the groove by the material of the filler cap 110. The groove can be continuous and shaped to accommodate the contour and configuration of a given heater element 106. The material of the filler cap 110 may include or may not include the same material as the platform 104 or the material of the heater coils 108. The material of the filler cap 110 can be selected to improve or promote heat transfer through the platform 104 to the panel 102 or other areas of the showerhead base assembly 100. In some examples, the deep or increased weld depth achieved by friction stir welding in the channel 124 enables the introduction of a heat sink. The heat sink provides a relatively cooler material body than the platform 104, and this cooler material can help prevent warping of the platform 104. The relative thermal conductivity of the material filling the cap 110 within the channel 124 may also be selected to assist in this regard.

[0045] Power to the heater coil 108 of the heater element 106 may be supplied via power lines 118. The gas distribution channels 114 distribute gas to the faceplate 102 having the orifices, as well as to other components of the showerhead base assembly 100. As shown, the power lines 118 and the gas distribution channels 114 may pass through a main stem 116 of the showerhead base assembly 100.

[0046] In some examples, friction stir welding is used to assemble or form components of the showerhead base assembly 100. For example, in region 120 ( Figure 1 ), friction stir welding is used to join the periphery of the platform 104 to the inner surface of the panel 102. In other examples, as shown in the figure, in the area 122 ( Figure 1 ), friction stir welding is used to form a filler cap 110 located above the heater coil 108 to secure the heater coil 108 within the body of the platform 104. Other base components may be joined or formed using similar methods. Other friction stir welded areas are possible.

[0047] refer to Figure 2 , a friction stir welding arrangement 200 is provided. A component 202 of a showerhead base assembly 100 can be joined to another component 204 in the manner shown. The component 202 shown may include, for example, an edge portion of a panel 102 disposed in an area 120. The other component 204 shown may include, for example, an edge portion of a platform 104 disposed in the same area 120. As shown, a downward force 206 is applied to a rotating friction stir welding (FSW) tool 208 that is advanced in a welding direction 210 between the edge portions of the two components 202 and 204. The FSW tool 208 includes a shoulder 212 and a pin 214. As the rotating FSW tool 208 advances, it forms a friction stir weld region 216 by moving the materials of the components 202 and 204 together. The friction stir weld region 216 thus formed includes a weld nugget 218 that joins the components 202 and 204 together. The nugget 218 has an advancing side 220 and a retreating side 222 corresponding to a rotational direction 224 of the tool.

[0048] In some instances, thermal non-uniformity within the pedestal or showerhead can lead to poor process performance "on the wafer" (on the substrate). In this case, process heat is lost or not properly directed to the desired area. Figures 3-4 , which depicts components of other examples of the present disclosure.

[0049] Figure 3 The heater element 300 shown in FIG. 1 has features for controlling or enhancing heat transfer within the showerhead base. The heater element 300 includes a heater coil 306 supplied by one or more power lines 304. In some showerhead base configurations, heat transfer between the faceplate 102 and the platform 104 (or backing plate) occurs primarily at their joint edges (e.g., at the Figure 1 The conduction is carried out in or near the region 120. Figure 3In the example shown, additional heat transfer tubes or rods 302 are provided. The rods 302 may be separately machined or formed to extend between the panel 102 and the platform 104 by friction stir welding, for example Figure 4 The other components of the showerhead base 400 may be the same or similar to those described above with respect to Figure 1 Those elements described for the showerhead base assembly 100.

[0050] The rod column 302 ( Figure 4 The heat transfer posts 302 may, for example, assist in heat conduction between the faceplate 102 and the platform 104 in the showerhead base assembly 100. In some examples, the heat transfer posts 302 may enhance the structural rigidity of the showerhead base assembly 100, or the positional securement of the heater element 106 in the platform 104, or the stiffness of the faceplate 102 or the platform 104. In some examples, the heat transfer posts 302 enable heat to escape from the faceplate 102 to the platform 104, or by radiation, to reduce the temperature of the faceplate 102 during wafer processing, and minimize or avoid deflection or warping of the faceplate. Other configurations or arrangements of the heat transfer posts 302 are possible. The material of the heat transfer posts 302 may be selected to enhance or hinder heat transfer between the faceplate 102 and the platform 104. The material selected for the posts 302 may be the same as or may be different from the material of the heater coil 108.

[0051] Figure 5 An exemplary fill cap 500 is shown, for example, including a series of curved or arcuate baffles 502 formed along its upper surface. Other configurations are possible. The fill cap 500 shown can secure the coil 108 of the heater element 106 within the channel 124 of the platform 104, as previously described with reference to FIG. Figure 1 described.

[0052] refer to Figure 6 In some examples of the showerhead base 600, the friction stir welded rod 302 (e.g., as shown in FIG. Figure 3 Not seen in Figure 6 Various combinations of baffles 502 (in the middle) and curved baffles 502 are interposed between the platform 604 and the faceplate 602 to control heat transfer and improve thermal uniformity. Other configurations and constructions of baffles 502 are possible. With the ability of friction stir welding to weld dissimilar metals, optimized material pairings, thicknesses, and spacing patterns can be employed and configured for a range of baffles. Other components of the showerhead base 600 may be the same or similar to those described above with respect to Figure 1 Those elements described for the showerhead base assembly 100.

[0053] refer to Figure 7-8Some exemplary embodiments may provide more detailed control over the heat and airflow 708 within the showerhead base 700. In some examples, concentric rings 702, 704, and 706 with spaced baffles 710 are provided to separate the faceplate 802 from the platform 804 (or 100, 400, 600) in the showerhead base 700. Figure 8 In some examples, the baffles 710 have apertures 712 and are spaced apart as shown (or otherwise) to enable specific or controlled airflow through the apertures 712 or through the baffles 710 in the spaced gaps between them.

[0054] Figure 10 1000 for friction stir welding. In some examples, during friction stir welding of a base component by a FSW tool 1004, a heater coil 1002 (e.g., Figure 1 1004) to control the cooling behavior and grain growth and size around the FSW weld. The FSW tool 1004 may include the aforementioned shoulder 1006 and pin 1008. Traditionally, FSW joints are cooled by natural convection, and process control of the weld zone is typically absent in the current context. In some examples of the present disclosure, activation of the heater coil 1002 during the FSW process may control (e.g., suppress) the cooling rate of the FSW weld to configure or provide a specific heat-affected zone, such as by controlling grain growth during solidification of the weld, and to improve weld quality and material properties.

[0055] The present disclosure includes method embodiments. Figure 11 An exemplary method 1100 for forming a showerhead base assembly for a substrate processing chamber includes: at operation 1102, providing a faceplate; at operation 1104, providing a platform disposed in the faceplate, the platform including a heater element extending through at least one groove in the faceplate, the at least one groove being contoured to receive at least a portion of the heater element extending through the at least one groove; at operation 1106, providing a power source for the heater element; and, at operation 1108, friction stir welding to join a periphery of the platform to an inner surface of the faceplate.

[0056] In some examples, the method 1100 further includes forming a plurality of apertures in the faceplate to enable gas to pass through the showerhead pedestal assembly to an underside of a substrate supported by the showerhead pedestal assembly.

[0057] In some examples, the method 1100 also includes forming a plurality of heat transfer struts extending between the faceplate and the opposing surfaces of the platform by friction stir welding.

[0058] In some examples, the friction stir weld includes a material that is different than the material of the faceplate or the platform and can form a friction stir welded joint between the faceplate and the platform.

[0059] In some examples, the method 1100 also includes selecting a material for the plurality of heat transfer struts to enhance or hinder heat transfer between the panel and the platform.

[0060] In some examples, the plurality of heat transfer rods are formed from the same material as the heater coil.

[0061] In some examples, the method 1100 also includes providing a fill cap for the showerhead base assembly, the fill cap including at least one baffle sized and configured to be positioned within the at least one groove within the faceplate.

[0062] In some examples, at least one baffle of the filler cap secures at least a portion of the heater coil within a corresponding groove within the panel.

[0063] In some examples, at least one baffle includes a curved structure that matches the profile of a corresponding groove in the panel.

[0064] In some examples, the method 1100 also includes forming the at least one baffle by friction stir welding.

[0065] In some examples, the method 1100 also includes providing at least one baffle along an upper surface of the fill cap.

[0066] In some examples, a portion of the fill cap includes a heat sink that provides a body of material that is relatively cooler than the material of the platform during operation of the showerhead base assembly.

[0067] In some examples, at least one baffle includes at least one aperture to enable gas to pass therethrough.

[0068] In some examples, the at least one baffle is provided in a series of baffles extending along the contour of the heater element in a spaced array, the spaced array of baffles including one or more gaps between consecutive baffles to enable gas to pass therethrough.

[0069] In some examples, the material included in the friction stir welding of the at least one baffle is different than the material of the faceplate or the heater element and is capable of producing a friction stir welded joint between the heater element and the faceplate.

[0070] In some examples, the at least one baffle is included in a plurality of concentric rings of baffles.

[0071] In some examples, at least one of the plurality of concentric rings of baffles includes baffles having a gap.

[0072] In some examples, each of the spaced baffles includes one or more apertures formed therein to enable a specific or controlled airflow through the one or more apertures.

[0073] In some examples, the gap between the pair of spaced baffles located in the at least one concentric ring of baffles is sized to enable a specific or controlled airflow therethrough.

[0074] In some examples, the method 1100 further includes energizing the heater element with a power source during forming the friction stir welded joint by friction stir welding.

[0075] Figure 9 A block diagram is provided to illustrate an example of a machine 900 on which one or more of the exemplary processing embodiments described herein may be implemented or controlled. In alternative embodiments, the machine 900 may operate as a standalone device or may be connected (e.g., via a network) to other machines. In a networked arrangement, the machine 900 may operate as a server machine, a client machine, or both in a server-client network environment. In one example, the machine 900 may function as a peer machine in a peer-to-peer (P2P) network (or other distributed network) environment. Furthermore, while a single machine 900 is shown, the term "machine" shall also be construed to include any collection of machines that individually or collectively execute a set (or multiple sets) of instructions 924 to perform any one or more of the methods described herein, for example, via cloud computing, software as a service (SaaS), or other computer cluster configurations.

[0076] The examples described herein may include logic and / or multiple components or mechanisms, or may be operated through logic and / or multiple components or mechanisms. A circuit system is a collection of circuits implemented in a tangible entity that includes hardware (e.g., simple circuits, gates, logic, etc.). Circuit system components can be flexible over time and due to the variability of the underlying hardware. A circuit system includes components that can perform specified operations individually or in combination when in operation. In one example, the hardware of the circuit system can be designed in a fixed, immutable manner to perform a specific operation (e.g., hard-wired). In one example, the hardware of the circuit system may include variably connected physical components (e.g., execution units, transistors, simple circuits, etc.) that include a computer-readable medium that is physically modified (e.g., magnetically, electrically, through a movable arrangement of constant mass particles, etc.) to encode instructions 924 for a specific operation. When the physical components are connected, the basic electrical properties of the hardware component are changed (e.g., from an insulator to a conductor, or vice versa). Instructions 924 enable embedded hardware (e.g., execution units or loading mechanisms) to generate components of the circuit system in hardware via variable connections to perform portions of a specific operation when in operation. Thus, when the device is operating, the computer-readable medium is communicatively coupled to other components of the circuit system. In one example, any of the physical components can be used in more than one component in more than one circuit system. For example, during operation, an execution unit can be used in a first circuit of a first circuit system at one point in time, and reused by a second circuit of the first circuit system, or by a third circuit of the second circuit system, at a different time.

[0077] The machine (e.g., a computer system) 900 may include a hardware processor 902 (e.g., a central processing unit (CPU), a hardware processor core, or any combination thereof), a graphics processing unit (GPU) 903, main memory 904, and static memory 906, some or all of which may communicate with each other via an interconnect (e.g., a bus) 908. The machine 900 may also include a display device 910, an alphanumeric input device 912 (e.g., a keyboard), and a user interface (UI) navigation device 914 (e.g., a mouse). In one example, the display device 910, the alphanumeric input device 912, and the UI navigation device 914 may be a touch screen display. The machine 900 may also include a mass storage device (e.g., a drive unit) 916, a signal generating device 918 (e.g., a speaker), a network interface device 920, and one or more sensors 921, such as a global positioning system (GPS) sensor, a compass, an accelerometer, or another sensor. The machine 900 may include an output controller 928 (e.g., a serial (e.g., Universal Serial Bus (USB)), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC)), etc.) connection) to communicate with or control one or more peripheral devices (e.g., a printer, a card reader, etc.).

[0078] The mass storage device 916 may include a machine-readable medium 922 on which one or more sets of data structures or instructions 924 (e.g., software) may be stored. These data structures or instructions 924 implement or are used by any one or more of the techniques or functions described herein. During execution thereof by the machine 900, the instructions 924 may also reside, completely or at least partially, within the main memory 904, within the static memory 906, within the hardware processor 902, or within the GPU 903. In one example, one or any combination of the hardware processor 902, the GPU 903, the main memory 904, the static memory 906, or the mass storage device 916 may constitute the machine-readable medium 922.

[0079] Although machine-readable medium 922 is shown as a single medium, the term "machine-readable medium" may include a single medium or multiple media (such as centralized or distributed databases and / or associated caches and servers) configured to store one or more instructions 924.

[0080] The term "machine-readable medium" may include any medium capable of storing, encoding, or carrying instructions 924 for execution by the machine 900 and causing the machine 900 to perform any one or more of the techniques of the present disclosure; or any medium capable of storing, encoding, or carrying data structures used by or related to such instructions 924. Non-limiting examples of machine-readable media may include solid-state memory and optical and magnetic media. In one example, mass machine-readable media includes a machine-readable medium 922 having a plurality of particles having an invariant mass (e.g., rest mass). Thus, mass machine-readable media is not a transient propagating signal. Specific examples of mass machine-readable media may include non-volatile memory, such as semiconductor memory devices (e.g., electronically programmable read-only memory (EPROM), electronically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The instructions 924 may be further transmitted or received via the network interface device 920 using a transmission medium over the communication network 926.

[0081] Although the embodiments have been described with reference to specific exemplary embodiments, it is apparent that various modifications and changes may be made to these embodiments without departing from the broader scope of the present disclosure. Therefore, the description and drawings are to be regarded as illustrative and not restrictive. The drawings forming part of this document show specific embodiments in an illustrative (but not restrictive) manner in which the subject matter may be practiced. The illustrated embodiments are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be used and derived therefrom so that structural and logical replacements and changes may be made without departing from the scope of the present disclosure. Therefore, this specific embodiment is not to be regarded as restrictive, and the scope of the various embodiments is limited only by the appended claims, together with the full scope of the equivalents to which these claims are assigned.

[0082] These embodiments of the subject matter of the present invention may be referred to herein individually and / or collectively by the term "invention", which is for convenience only and is not intended to voluntarily limit the scope of this application to any single invention or inventive concept (if in fact more than one invention or inventive concept is disclosed). Therefore, although specific embodiments are shown and described herein, it should be understood that any configuration calculated to achieve the same purpose may replace the specific embodiments shown. This disclosure is intended to cover all adjustments or variations of the various embodiments. After reading the above description, combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art.

Claims

1. A showerhead base assembly for a substrate processing chamber, the showerhead base assembly comprising: panel; as well as A platform connected to the panel, the platform including at least one groove, a heater element at least partially disposed in the at least one groove, and a fill cap, the fill cap also at least partially disposed in the at least one groove to secure the heater element in the at least one groove, wherein the at least one groove is contoured to receive at least a portion of the heater element, and the fill cap is secured to the platform by a friction stir welded joint, and wherein the fill cap includes at least one baffle protruding from the platform.

2. The showerhead base assembly of claim 1 , wherein the faceplate comprises a plurality of orifices distributed on a surface of the faceplate facing away from the platform and configured to allow gas to flow through the showerhead base assembly and away from the surface of the faceplate facing away from the platform.

3. The spray head base assembly according to claim 1, wherein: The heater elements follow a curvilinear path distributed over the platform, and At least a portion of the fill cap follows the curvilinear path. The showerhead base assembly of claim 3 , wherein the curved path is a serpentine path.

5. A spray head base assembly according to claim 3 or 4, wherein the heater element includes at least a first segment following a first arcuate path, a second segment following a second arcuate path, and a third segment following a third arcuate path, wherein the first arcuate path, the second arcuate path, and the third arcuate path are concentric with each other and each has a different radius.

6. The spray head base assembly of claim 5, wherein the heater element further comprises a fourth segment following a fourth arcuate path and a fifth segment following a fifth arcuate path, the fourth arcuate path and the fifth arcuate path being concentric with each other, the fourth arcuate path and the second arcuate path having the same radius, and the fifth arcuate path and the third arcuate path having an equal radius.

7. The showerhead base assembly of claim 1, wherein the at least one baffle comprises a curved structure that matches a contour of a corresponding portion of the at least one groove in the platform.

8. The showerhead base assembly of claim 1, wherein the at least one baffle comprises a friction stir weld material.

9. The showerhead base assembly of claim 1, wherein the at least one baffle is provided along an upper surface of the fill cap.

10. The showerhead base assembly of claim 1, wherein a portion of the fill cap includes a heat sink that provides a body of material that is relatively cooler than a material of the platform during operation of the showerhead base assembly.

11. The showerhead base assembly of claim 1, wherein the at least one baffle comprises at least one orifice to enable gas to pass therethrough.

12. A showerhead base assembly according to claim 1, wherein the at least one baffle is provided in a series of baffles, the series of baffles extending in a separated array along the path followed by the heater element, the separated array of baffles including one or more gaps located between consecutive baffles to allow gas to pass therethrough.

13. The showerhead base assembly of claim 8, wherein the friction stir welding material of the at least one baffle is different from a material of the faceplate or the heater element and is capable of forming a friction stir welded joint between the heater element and the faceplate.

14. The showerhead base assembly of claim 1, wherein the at least one baffle comprises a plurality of concentric rings of baffles.

15. The showerhead base assembly of claim 14, wherein at least one of the plurality of concentric rings of baffles comprises spaced apart baffles.

16. The showerhead base assembly of claim 15, wherein each of the spaced apart baffles includes one or more apertures formed therein to enable a specific or controlled gas flow through the one or more apertures.

17. The showerhead base assembly of claim 15, wherein gaps between pairs of spaced-apart baffles in at least one ring of baffles are sized to enable a specific or controlled gas flow therethrough.

18. The showerhead base assembly of claim 1, further comprising a power source connected to the heater element, wherein the heater element is powered by the power source during formation of the friction stir welded joint.

19. A method of forming a showerhead pedestal assembly for a substrate processing chamber, the method comprising: Provide panels; connecting a platform to the panel, the platform including a heater element extending through at least one groove in the platform, the at least one groove being contoured to receive at least a portion of the heater element extending therethrough; installing a fill cap into the at least one groove to secure the heater element in the at least one groove, forming a friction stir welded joint between the fill cap and the platform; as well as At least one baffle is formed on the filling cap to protrude from the platform.

20. The method of claim 19, further comprising forming a plurality of apertures in the faceplate to enable gas to pass through the showerhead pedestal assembly to an underside of a substrate supported by the showerhead pedestal assembly.

21. The method of claim 19, wherein: The heater elements follow a curvilinear path distributed over the platform, and At least a portion of the fill cap follows the curvilinear path.

22. The method of claim 21, wherein the curved path is a serpentine path.

23. The method of claim 21, wherein the heater element comprises at least a first segment following a first arcuate path, a second segment following a second arcuate path, and a third segment following a third arcuate path, wherein the first arcuate path, the second arcuate path, and the third arcuate path are concentric with each other and each has a different radius.

24. The method of claim 23, wherein the heater element further comprises a fourth segment following a fourth arcuate path and a fifth segment following a fifth arcuate path, the fourth arcuate path and the fifth arcuate path being concentric with each other, the fourth arcuate path and the second arcuate path having the same radius, and the fifth arcuate path and the third arcuate path having an equal radius.

25. The method of claim 19, wherein the at least one baffle comprises a curved structure that matches a contour of a corresponding portion of the at least one groove in the platform.

26. The method of claim 19, further comprising forming the at least one baffle by friction stir welding.

27. The method of claim 19, further comprising providing the at least one baffle along an upper surface of the fill cap.

28. The method of claim 19, wherein a portion of the fill cap comprises a heat sink that provides a body of material that is relatively cooler than a material of the platform during operation of the showerhead base assembly.

29. The method of claim 19, wherein the at least one baffle comprises at least one orifice to enable gas to pass therethrough.

30. A method according to claim 19, wherein the at least one baffle is provided in a series of baffles, the series of baffles extending in a spaced-apart array along the path followed by the heater element, the spaced-apart array of baffles including one or more gaps located between consecutive baffles to enable gas to pass therethrough.

31. The method of claim 26, wherein the material included in the friction stir welding of the at least one baffle is different than the material of the face plate or the heater element and is capable of forming a friction stir welded joint between the heater element and the face plate.

32. The method of claim 19, wherein the at least one baffle comprises a plurality of concentric rings of baffles.

33. The method of claim 32, wherein at least one of the plurality of concentric rings of baffles comprises spaced apart baffles.

34. The method of claim 33, wherein each of the spaced apart baffles includes one or more apertures formed therein to enable a specific or controlled airflow through the one or more apertures.

35. The method of claim 33, wherein gaps between pairs of spaced apart baffles in at least one ring of baffles are sized to enable a specific or controlled gas flow therethrough.

36. The method of claim 19, further comprising providing a power source for the heater element and energizing the heater element with the power source during forming the friction stir welded joint.

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