Ground electrode formed in electrostatic chuck for plasma processing chamber

Abstract

Disclosed herein is a substrate support assembly having a ground electrode mesh disposed in the substrate support assembly along a side surface of the substrate support assembly. The substrate support assembly has a body. The body has an outer top surface, an outer side surface, and an outer bottom surface that enclose an interior of the body. The body has a ground electrode mesh disposed in the interior of the body proximate the outer side surface, wherein the ground electrode does not extend through to the outer side top surface or the outer side surface.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to plasma processing chambers. More specifically, embodiments of the present disclosure relate to a ground electrode for a substrate support assembly disposed in a plasma processing chamber. BACKGROUND

[0002] Plasma processing systems are used to form devices on substrates, such as semiconductor wafers or transparent substrates. Typically, a substrate is held to a support for processing. The substrate can be held to the support by vacuum, gravity, electrostatic forces, or by other suitable techniques. During processing, a precursor gas or gas mixture in the chamber is energized (e.g., excited) into a plasma by applying power, such as radio frequency (RF) power, from one or more power sources coupled to electrodes in the chamber. The excited gas or gas mixture reacts to form a layer of material on a surface of the substrate. The layer can be, for example, a passivation layer, a gate insulator, a buffer layer, and / or an etch stop layer.

[0003] During a plasma enhanced chemical vapor deposition (PECVD) process, a capacitively coupled plasma, also referred to as a source plasma, is formed between a substrate support and a gas distribution plate. The RF return path of the plasma passes through the substrate support and the chamber liner. Asymmetries in the RF return path due to poor or broken groundings can cause non-uniformity or skew in the process results (e.g., etching, deposition, etc.). A processing chamber typically includes a substrate support or pedestal disposed in the processing chamber to support a substrate during processing, and a showerhead having a faceplate for introducing process gases into the processing chamber. The plasma is generated by two RF electrodes, with the showerhead serving as the top electrode (i.e., cathode) and the substrate support serving as the bottom electrode (i.e., anode). In some processes, the pedestal can include an embedded metal mesh to serve as the bottom electrode. Process gases flow through the showerhead, and a plasma is generated between the two electrodes. In conventional systems, the RF current flows through the plasma from the showerhead top electrode to the heater bottom electrode. The RF current will pass through a nickel RF rod in the pedestal, and then return through the pedestal structure in the inner chamber wall. The RF return path provides process stability and prevents arcing in the chamber, thereby extending the useful life of the chamber components. However, the vertical walls of the substrate support are largely under- grounded, which can promote the formation of a parasitic plasma below the support surface of the substrate support.

[0004] Accordingly, what is needed is an improved RF return path in a plasma processing chamber. SUMMARY

[0005] Disclosed herein is a substrate support assembly having a ground electrode mesh disposed in the substrate support assembly along a side surface of the substrate support assembly and a method for forming a ground electrode mesh. The substrate support assembly has a body. The body has an outer top surface, an outer side surface, and an outer bottom surface to enclose an interior of the body. The body has a ground electrode mesh disposed in the interior of the body adjacent to the outer side surface, wherein the ground electrode does not extend through to the outer side top surface or the outer side surface.

[0006] Disclosed herein is a method for forming an electrostatic chuck (ESC). The method begins by sintering an aluminum nitride (AIN) or aluminum oxide body having a heater, an RF electrode mesh, and a high voltage (HV) ESC electrode mesh. A ground electrode mesh is disposed along one or more outer surfaces of the sintered AIN body. The ground electrode mesh and the sintered body are encased in aluminum powder to form an ESC body. The ESC body is sintered to form the ESC.

[0007] Disclosed herein is another method for forming an ESC. The method begins by printing an RF electrode on a top surface of a first AIN sheet. A plurality of first through holes are formed in the first AIN sheet. A heater is printed on a top surface of a second AIN sheet. A plurality of second through holes are formed in the second AIN sheet. The second through holes are vertically aligned with the first through holes. An HV ESC electrode is printed on a top surface of a third AIN sheet. A plurality of third through holes are formed in the third AIN sheet. The third through holes are vertically aligned with the first through holes. A ground mesh is printed on a top surface of a fourth AIN sheet. A plurality of fourth through holes are formed in the fourth AIN sheet. The fourth through holes are vertically aligned with the first through holes. A fifth AIN sheet is placed on the top surface of the first sheet for an ESC body. BRIEF DESCRIPTION OF DRAWINGS

[0008] So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, can be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only example embodiments and therefore are not to be considered

[0009] Figure 1 is a schematic cross-sectional view of a process chamber including a substrate support assembly according to one embodiment.

[0010] Figures 2A-2D is a schematic cross-sectional view of a substrate support assembly of Figure 1 is a schematic cross-sectional view of a substrate support assembly of is a schematic cross-sectional view of a substrate support assembly of

[0011] Figures 3A-3B is a schematic cross-sectional view of a substrate support according to another embodiment that can be used in place of Figure 1 the substrate support of

[0012] Figure 4 is a schematic perspective view of a substrate support assembly and a tube socket according to an embodiment. Figure 1

[0013] Figure 5 is a schematic cross-sectional view of a process chamber including a substrate support assembly according to a second embodiment.

[0014] Figure 6 is a partial schematic cross-sectional view of a process chamber including a substrate support assembly according to a third embodiment.

[0015] Figure 7 is a method for forming an ESC.

[0016] Figure 8 is another method for forming an ESC.

[0017] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements that are common to the various figures. It is contemplated that elements and / or features of one embodiment can be beneficially incorporated into other embodiments without further recitation.

[0018] DETAILED DESCRIPTION

[0019] Embodiments of the present disclosure generally relate to vertical ground electrodes disposed along a perimeter of a substrate support for use in a plasma processing chamber. A substrate support assembly includes a substrate support and a tube socket. The substrate support has a ceramic body. The ceramic body has an outer vertical wall, a bottom surface, and a support surface. The support surface is configured to support a substrate thereon. An RF electrode and a heater are disposed within the ceramic body. Additionally, a vertical ground electrode for a plasma RF return path is disposed within the ceramic body along the outer vertical wall. The vertical ground electrode is adapted to handle large currents. The vertical ground electrode is electrically coupled to a ground electrode in the ceramic body. The tube socket is attached to the bottom surface of the ceramic body and includes a tubular wall. A ground is disposed through the tube socket and couples the vertical ground electrode to the plasma RF return path. Advantageously, the vertical ground electrode provides proper grounding along the outer vertical wall of the ceramic body that is external to the RF electrode and the heater. The brazed connection between the tube socket and the ceramic body allows for operation even at temperatures exceeding 650 degrees Celsius. The vertical ground electrode reduces or eliminates parasitic plasma under the heater, thus reducing power loss.

[0020] ​Embodiments herein are illustratively described below with reference to use in a PECVD system configured to process substrates. However, it should be understood that the disclosed subject matter has utility in other system configurations, such as etch systems, other chemical vapor deposition systems, physical vapor deposition systems, and any other system in which a substrate is exposed to a plasma within a process chamber. It should also be understood that embodiments disclosed herein can be adapted to be practiced in other process chambers configured to process substrates of various sizes and dimensions.

[0021] Figure 1 is a schematic cross-sectional view of a process chamber 100 including a substrate support assembly 128 according to one embodiment described herein. In Figure 1 the example, the process chamber 100 is a PECVD chamber. As Figure 1 shown, the process chamber 100 includes one or more sidewalls 102, a bottom 104, a gas distribution plate 110, and a lid plate 112. The sidewalls 102, the bottom 104, and the lid plate 112 collectively define a processing volume 106. The gas distribution plate 110 and the substrate support assembly 128 are disposed in the processing volume 106. The processing volume 106 is accessed via a sealable slit valve opening 108 formed through the sidewall 102 such that a substrate 105 can be transferred into and out of the process chamber 100. A vacuum pump 109 is coupled to the chamber 100 to control the pressure within the processing volume 106.

[0022] The gas distribution plate 110 is coupled to the lid plate 112 at its periphery. A gas source 120 is coupled to the lid plate 112 to provide one or more gases through the lid plate 112 to a plurality of gas passages 111 formed in the lid plate 112. The gases flow through the gas passages 111 and into the processing volume 106 toward the substrate receiving surface 132.

[0023] An RF power source 122 is coupled to the lid plate 112 and / or directly to the gas distribution plate 110 through an RF power feedline 124 to provide RF power to the gas distribution plate 110. Various RF frequencies can be used. For example, the frequency can be between about 0.3 MHz and about 200 MHz, such as about 13.56 MHz. An RF return path 125 couples the substrate support assembly 128 to the RF power source 122 through the sidewall 102. The RF power source 122 creates an electric field between the gas distribution plate 110 and the substrate support assembly 128. The electric field forms a plasma from the gases present between the gas distribution plate 110 and the substrate support assembly 128. The RF return path 125 completes the electrical circuit for the RF energy, preventing stray plasma from causing RF arcing due to voltage differences between the substrate support assembly 128 and the sidewall 102. Thus, the RF return path 125 mitigates arcing that causes process drift, particle contamination, and damage to chamber components.

[0024] The substrate support assembly 128 includes a substrate support 130 and a stem 134. The stem 134 is coupled to a lift system 136 that is adapted to raise and lower the substrate support assembly 128. The substrate support 130 includes a substrate receiving surface 132 for supporting the substrate 105 during processing. A lift pin 138 is movably disposed through the substrate support 130 to move the substrate 105 to and from the substrate receiving surface 132 to facilitate substrate transfer. An actuator 114 is used to extend and retract the lift pin 138. During processing, a ring assembly 133 can be placed over the periphery of the substrate 105. The ring assembly 133 is configured to prevent or reduce unwanted deposition on the surface of the substrate support 130 that is not covered by the substrate 105 during processing.

[0025] The substrate support 130 can also include heating and / or cooling elements 139 to maintain the substrate support 130 and the substrate 105 positioned thereon at a desired temperature. In one embodiment, the heating and / or cooling elements 139 can be used to maintain the temperature of the substrate support 130 and the substrate 105 disposed thereon to less than about 800 °C or lower during processing. In one embodiment, the heating and / or cooling elements 139 can be used to control the substrate temperature to less than 650 °C, such as between 300 °C and about 400 °C. The substrate support 130 is described in further detail in Figures 2A-2D and Figures 3A-3B The substrate support 130 is described in further detail in

[0026] Figures 2A-2D is a schematic cross-sectional view of the substrate support assembly 128 of Figure 1 having the substrate support 130 of one embodiment. Figures 2A-2D A simplified assembly or configuration of the substrate support assembly 128 is shown over four time snapshots. These figures show the creation of ground electrodes within and along the periphery of the substrate support 130 (i.e., one embodiment of the substrate support 130). The creation of the ground electrodes will be discussed in turn. However, it should be understood that the substrate support 130 depicted in Figures 2A-2D The creation of the substrate support 130 will be discussed in turn. However, it should be understood that the substrate support 130 depicted in Figures 2A-2D may be formed utilizing a number of different techniques and possibly even different sequences of operations.

[0027] Figure 2A A view of the body 210 is shown in Figure 2AThe top, bottom, and sides are reversed. The RF mesh 224 is disposed within the body 210. The high voltage chucking electrode 222 and optional heater 226 are also disposed within the body 210. The RF mesh 224, high voltage chucking electrode 222, and heater 226 each have connections that individually extend through the bottom surface 205 of the body 210. These connections provide individual control and power to each of the RF mesh 224, high voltage chucking electrode 222, and heater 226. The body 210 is a ceramic material. The body 210 can be formed by sintering a ceramic material such as aluminum nitride (AIN) or aluminum oxide powder or other suitable material. The RF mesh 224 is embedded in the body 210. The RF mesh 224 has electrical connections that extend through the bottom surface 205 of the body 210.

[0028] Figure 2B The body 201 is shown surrounded by a ground electrode 228 on the bottom surface 205 and side surface 206. The ground electrode 228 can form a continuous cylindrical wall or alternatively a cage-like structure around the body 210 along the side surface 206. For example, the cage-like structure can be formed by 3 to 24 pins for the ground electrode 228. Each pin of the ground electrode 228 can have a diameter between about 0.5 mm to about 2 mm. The pins are formed of an RF conductive material such as molybdenum. That is, the ground electrode 228 can be continuous on the inside along the radius of the body 201 or alternatively can be discontinuous on the inside along the radius. In this way, the ground electrode 228 forms a ground path completely around the side surface 206 of the ESC 200. The body 201 and ground electrode 228 are surrounded by a cap layer 238. Contact pads 229 can extend through the cap layer 238 along a mounting surface 232 on the bottom of the ESC body 250 of the substrate support 130. The contact pads 229 are configured to electrically couple the ground electrode 228 with an RF grommet or other connection. The cap layer 238 can be AIN powder or other suitable ceramic material. Alternatively, the cap layer 238 can be another dielectric material suitable for exposure in a plasma processing environment. The ground electrode 228 extends through the cap layer 238 at the bottom surface 205 of the body 210 to provide an electrical connection to the ground electrode 228. The button 227 can be formed of an RF conductive material. The button 227 extends between and completes an electrical circuit between the RF mesh 224 and the ground electrode 228. The button 227 can be formed of molybdenum or other suitable metallic material. The RF mesh 224 embedded in the body 201 has electrical connections that extend through the cap layer 238 at the bottom surface 205 of the body 210 to provide an electrical connection to the RF mesh 224.

[0029] Figure 2CA capping layer 238 is shown encapsulating the ground electrode 228 and the body 210 to form the ESC 130. The capping layer 238 can be sintered to form an integral structure with the body 210. The ESC 130 has an ESC body 250. The ESC body 250 has a support surface 204, a side surface 260, and a mounting surface 232. The mounting surface 232 corresponds to the bottom surface 205 of the body 210. The mounting surface 232 has electrical connections extending through it corresponding to the ground electrode 228. The mounting surface 232 may additionally have electrical connections for one or more of the RF grid 224, the high-voltage clamping electrode 222, and the heater 226, which extend through the mounting surface to provide power and control to the respective RF grid 224, high-voltage clamping electrode 222, and heater 226. The ground electrode 228 and / or contact pads 229 exposed at the bottom may be protected by yttrium, aluminum, nickel, or a nickel-cobalt-iron alloy.

[0030] Figure 2D A mounting surface 232 attached to the ESC body 250 is shown, for forming a socket 134 for the substrate support assembly 128. The socket 280 can be attached using any suitable technique, such as adhesive, mechanical fasteners, brazing, soldering, etc. A corresponding RF mesh 224, high-voltage clamping electrode 222, and heater 226 are electrically coupled to wiring laid within the socket 280. A ground electrode 228 connection can be electrically coupled to the socket 280. Alternatively, the ground electrode 228 may be electrically coupled to wiring or other conductive elements within the socket 280. Reference will be made below. Figure 4 The electrical connection of the grounding electrode 228 in the tube socket 280 is further discussed.

[0031] Figures 3A-3B This is a schematic cross-sectional view of a substrate support 330 according to another embodiment, which can be used as an alternative. Figure 1 The substrate support 130. The substrate support 330 can be formed by printing, bonding, sintering or forming multiple sheets by one or more suitable techniques, including in a plasma processing chamber (such as one or more deposition chambers, etching chambers, etc.).

[0032] exist Figure 3A In this embodiment, the substrate support 330 is formed of multiple layers. In one embodiment, the substrate support 330 is formed of a first layer 301, a second layer 302, a third layer 303, a fourth layer 304, a fifth layer 305, a sixth layer 306, a seventh layer 307, and an eighth layer 308. It should be understood that the substrate support 330 may be formed of more or fewer than eight layers. However, the above embodiment will be discussed further, wherein the number of layers forming the substrate support 330 is eight.

[0033] The first layer 301 has a first top surface 309, a first bottom surface 371, and a first side surface 361. The second layer 302 has a second top surface 392, a second bottom surface 372, and a second side surface 362. The third layer 303 has a third top surface 393, a third bottom surface 373, and a third side surface 363. The fourth layer 304 has a fourth top surface 394, a fourth bottom surface 174, and a fourth side surface 364. The fifth layer 305 has a fifth top surface 395, a fifth bottom surface 375, and a fifth side surface 365. The sixth layer 306 has a sixth top surface 396, a sixth bottom surface 376, and a sixth side surface 366. The seventh layer 307 has a seventh top surface 397, a seventh bottom surface 377, and a seventh side surface 367. The eighth layer 308 has an eighth top surface 398, an eighth bottom surface 378, and an eighth side surface 368.

[0034] A plurality of ground pads 310 are disposed between the first bottom surface 371 and the second top surface 392 proximate the first side surface 361. The ground pads 310 are formed of an electrically conductive material, such as a metal. An HV electrode 322 can additionally be disposed between the first bottom surface 371 and the second top surface 392. A plurality of vias 312 in the second layer 302 are disposed below the plurality of ground pads 310 on the second top surface 392 of the second layer 302 proximate the second side surface 362. The vias 312 are filled with an electrically conductive material, such as the same electrically conductive material as the pads, and are electrically connected to the ground pads 310. The number of vias 312 corresponds to the number of ground pads 310. In another example, the vias 312 formed in the second layer 302 are twice the number of ground pads 310 disposed between the second layer 302 and the first layer 301. It is important to understand that each ground pad 310 has one or more corresponding vias 312 filled with an electrically conductive material that is attached to and electrically coupled to the ground pad.

[0035] Additional ground pads 310 are disposed between the second bottom surface 372 and the third top surface 393 proximate the second side surface 362. Vias 312 in the third layer 303 are disposed below the plurality of ground pads 310 on the third top surface 393 proximate the third side surface 363. The ground pads 310 between the second bottom surface 372 and the third top surface 393 are electrically coupled to the vias in the second layer 302 and the vias in the third layer 303. An RF mesh 324 can additionally be disposed between the second bottom surface 372 and the third top surface 393. In one embodiment, the vias 312 in the second layer 302 are aligned with the vias 312 in the third layer. However, the alignment of the vias 312 in the respective second layer 302 and third layer 303 is less important than the electrical conductivity between them. In a second embodiment, the vias 312 in the second layer 302 are not aligned with the vias 312 in the third layer 303.

[0036] An additional ground pad 310 is disposed between the fourth bottom surface 374 and the fifth top surface 395 proximate the fifth side surface 365. The via 312 in the fifth layer 305 is disposed below the plurality of ground pads 310 on the fifth top surface 395 proximate the fifth side surface 365. The ground pads 310 between the fourth bottom surface 374 and the fifth top surface 395 are electrically coupled to the via 312 in the fourth layer 304 and the via 312 in the fifth layer 305. As discussed above, the via 312 in the fourth layer 304 is electrically coupled to the via 312 in the fifth layer 305 by the ground pads 310.

[0037] An additional ground pad 310 is disposed between the fourth bottom surface 374 and the fifth top surface 395 proximate the fifth side surface 365. The via 312 in the fifth layer 305 is disposed below the plurality of ground pads 310 on the fifth top surface 395 proximate the fifth side surface 365. The ground pads 310 between the fourth bottom surface 374 and the fifth top surface 395 are electrically coupled to the via 312 in the fourth layer 304 and the via 312 in the fifth layer 305. As discussed above, the via 312 in the fourth layer 304 is electrically coupled to the via 312 in the fifth layer 305 by the ground pads 310.

[0038] An additional ground pad 310 is disposed between the fourth bottom surface 374 and the fifth top surface 395 proximate the fifth side surface 365. The via 312 in the fifth layer 305 is disposed below the plurality of ground pads 310 on the fifth top surface 395 proximate the fifth side surface 365. The ground pads 310 between the fourth bottom surface 374 and the fifth top surface 395 are electrically coupled to the via 312 in the fourth layer 304 and the via 312 in the fifth layer 305. As discussed above, the via 312 in the fourth layer 304 is electrically coupled to the via 312 in the fifth layer 305 by the ground pads 310.

[0039] An additional ground pad 310 is disposed between the fourth bottom surface 374 and the fifth top surface 395 proximate the fifth side surface 365. The via 312 in the fifth layer 305 is disposed below the plurality of ground pads 310 on the fifth top surface 395 proximate the fifth side surface 365. The ground pads 310 between the fourth bottom surface 374 and the fifth top surface 395 are electrically coupled to the via 312 in the fourth layer 304 and the via 312 in the fifth layer 305. As discussed above, the via 312 in the fourth layer 304 is electrically coupled to the via 312 in the fifth layer 305 by the ground pads 310.

[0040] The ground electrode 328 is disposed between the seventh bottom surface 377 and the eighth top surface 398. The ground electrode 328 extends to the eighth side surface 368. The eighth layer 308 has a center 399. The ground electrode 328 extends through the center 399 to electrically connect with the center. The through hole 312 can additionally extend through the eighth layer 308. A ground pad 329 can be electrically coupled to the ground electrode 328 through the through hole 312. The ground pad 329 is configured to electrically couple the ground electrode 328 with an RF grommet or other connection. The HV electrode 322, the RF mesh 324, and the heater coil 326 have electrical connections extending through the center 399 to provide power and control to the respective HV electrode 322, RF mesh 324, and heater 386. The ground electrode 328 and / or the ground pad 329 exposed at the bottom can be protected by yttrium, aluminum, nickel, or inconel.

[0041] Figure 3B The ESC 330 is shown formed from the components of the first layer 301 through the eighth layer 308 discussed above. Each of the plurality of through holes 312 and each ground electrical pad 310 disposed within the ESC 330 by the arrangement of the electrically coupled through holes 312 and the ground electrical pad 310 adjacent the side surface 360 between the first layer 301 and the eighth layer 308 form a ground path through the ESC 330 adjacent the side surface 360. The through holes 312 are substantially orthogonal to the substrate support surface 350 of the ESC 330. The through holes 312 and the ground electrical pad 310 are disposed within the body of the ESC 330 in a cylindrical pattern. The through holes 312 and the ground electrical pad 310 can form a continuous cylindrical wall or alternatively a cage-like structure. For example, the cage-like structure can be formed from 3 to 24 pin-like structures for the through holes 312. The diameter of each through hole 312 can be between about 0.5 mm to about 2 mm. The through holes can be filled with metal to form a continuous conductive path. Alternatively, the through holes 312 can be continuous along the radius of the ESC 330. In this way, the through holes 312 form a ground path that completely surrounds the side surface 360 of the ESC 330.

[0042] Reference will now be made to Figure 4 The electrical coupling of the ground electrode 228 / 328 to the pipe socket is discussed. Figure 4 is a schematic perspective view of a substrate support assembly 128 according to one embodiment. Figure 1 is a schematic perspective view of a substrate support assembly 128 according to one embodiment. Figures 3A-3B The ESC 330 discussed is equally applicable with respect to Figure 4 The substrate support assembly 128 and electrical ground connection discussed. The pipe socket 134 can be attached to the ESC 130 / 330 by a variety of suitable techniques for forming the substrate support assembly 128. For example, the pipe socket 134 can be welded, chemically bonded, or mechanically bonded to the ESC 130 / 330. In one embodiment, the pipe socket 134 is diffusionally bonded to the ESC 130 / 330.

[0043] The pipe base 134 has a hollow interior 434. A metal ground pipe 442 is disposed within the hollow interior 434 of the pipe base 134. The metal ground pipe 442 is a cylindrical body of metal. The metal ground pipe 442 can be formed of molybdenum or nickel-cobalt-iron alloy coated with Mo, Au, or Ag or other suitable material. The metal ground pipe 442 has an interior region 444. The interior region 444 is configured to provide space for electrical connections to the ESC 130 to pass through the metal ground pipe 442. The metal ground pipe 441 provides an RF ground coaxial return (shown in FIGS. Figures 2A-2D and Figure 3B The metal ground pipe 442 has a plurality of ground pipe connectors 420. The ground pipe connectors 420 are configured to mate with respective web connectors 410 as shown by the arrows 415. The ground pipe connectors 420 can be tabs or protrusions in the metal ground pipe 442. The ground pipe connectors 420 can fit into the respective web connectors 410 to provide an electrical connection to the ground web 228 / 238 to complete the ground path. In one embodiment, the ground electrode 228 is brazed at the ground pipe connectors 420 to complete the ground return path disposed within the side 260 / 360 of the ESC 130 / 330. Thus, an RF shield is created at the bottom and edges of the substrate support 130 by the shielding effect where RF would exist on the wiring within the shaft, heater, and RF web.

[0044] Figure 5 is a schematic cross-sectional view of a processing chamber 500 including a substrate support assembly 128 according to a second embodiment. The processing chamber 500 has a main body 501. The main body 501 has a sidewall 502, a bottom 504, and a cover plate 512. The sidewall 502, the bottom 504, and the cover plate 512 define an interior volume 506 of the processing chamber 500. The substrate support assembly 128 is disposed within the interior volume 506 of the processing chamber 500. A plasma 142 can be formed in the interior volume and sustained by RF energy supplied via the processing chamber 500.

[0045] The substrate support assembly 128 has an ESC 530 and a metal ground pipe 560. The chucking electrode 528 is disposed within the ESC 530. A metal coating 554 is disposed on an outer surface of the substrate support assembly 128. The metal coating 554 can be formed of molybdenum, aluminum, copper, or other suitable electrically conductive material. The metal coating 554 is electrically coupled to the RF ground loop.

[0046] The metal ground tube 560 can be formed of molybdenum, aluminum, copper, or other suitable electrically conductive material. The metal ground tube 560 is electrically coupled to the RF ground loop. One or more RF gaskets 550, 552 can be disposed between the metal ground tube 560 and chamber components that are part of the RF ground path. The RF gaskets 550, 552 are electrically conductive to and transmit RF energy there through to form the RF ground circuit. The RF gaskets 550, 552 can be formed of nickel, copper, aluminum, molybdenum, or other suitable material. The RF gasket 550 is disposed between the metal ground tube 560 and the sidewall 502 or the cover plate 512 of the processing chamber 500. Additionally, the RF gasket 552 can be disposed between the metal ground tube 560 and the metal coating 554 to couple RF energy there between. Advantageously, the RF ground return path can be made short to reduce the electrical resistance in the ground path and reduce the voltage drop between various chamber components to prevent arcing.

[0047] Figure 6 is a partial schematic cross-sectional view of a processing chamber 600 including a substrate support assembly 128 according to a third embodiment. The processing chamber 600 has a body 601. The body has a sidewall 602, a bottom 604, and a showerhead 612. The sidewall 602, the bottom 604, and the showerhead 612 define an interior volume 606. The substrate support assembly 128 is disposed within the interior volume 606. An RF generator 680 couples an electrode 682 in the showerhead 612. The RF generator 680 has an RF return path 688 for completing an RF circuit in the presence of a plasma.

[0048] The substrate support assembly 128 has a heater 626, an HV chucking mesh 622, and an RF mesh 624 disposed in the substrate support assembly 128. The substrate support assembly 128 has an outer surface 629. A metal coating 684 is disposed on the outer surface 629 of the substrate support assembly 128. The metal coating 684 is formed of nickel, copper, aluminum, molybdenum, or other suitable material. The metal coating 684 is part of the RF return path 688 and completes the ground for RF when the RF generator 680 is energized. A protective coating 632 can be disposed on the metal coating 684 to protect the metal coating 684 from corrosion and help maintain the conductivity of the metal coating 684. The protective coating 632 can be formed of yttria, AIN, AI2O3, or other suitable material. The protective coating 632 maintains the connection for the RF ground path for the substrate support assembly 128. Advantageously, the RF ground path for maintaining a plasma can be maintained and provide a longer useful life for the substrate support assembly 128.

[0049] Figure 7is a method 700 for forming an ESC. The method 700 begins at operation 710 by sintering an AlN body with heaters, RF electrode mesh, and HV ESC electrode mesh. At operation 720, a ground electrode mesh is disposed along one or more outer surfaces of the sintered AlN body. At operation 730, the ground electrode mesh and sintered body are encapsulated in aluminum powder to form an ESC body. At operation 740, the ESC body is sintered to form an ESC.

[0050] Figure 8 is another method 800 for forming an ESC. The method 800 begins at operation 810 by printing HV ESC electrodes on a top surface of a first AlN sheet. At operation 830, a ground plane electrode is printed on a top surface of a second ceramic sheet. At operation 840, a plurality of second vias are formed in the second ceramic sheet and connected to the ground plane electrode. At operation 850, one or more heater electrodes are printed on a top surface of a third ceramic sheet. At operation 860, a plurality of third vias are formed in the third ceramic sheet, the third vias being vertically aligned with the second vias. At operation 870, a ground mesh is printed on a top surface of a fourth ceramic sheet. The ground mesh is electrically coupled to the ground plane electrode through the vias. At operation 880, a plurality of fourth vias are formed in the fourth ceramic sheet, the fourth vias being vertically aligned with the second vias. At operation 890, a fifth ceramic sheet is placed on the top surface of the first sheet for obtaining an ESC body.

[0051] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure can be devised without departing from the basic scope thereof, and the scope of the present disclosure is determined by the claims that follow.

Claims

1. A substrate support assembly, comprising: a body having an outer top surface, an outer side surface, and an outer bottom surface, the outer top surface, the outer side surface, and the outer bottom surface enclosing an interior of the body, the body including: a cylindrical ground electrode disposed vertically in the interior of the body and adjacent to the outer side surface; and an RF electrode electrically coupled to the cylindrical ground electrode, wherein the RF electrode is disposed horizontally in the interior of the body, wherein the cylindrical ground electrode is electrically coupled to a contact pad extending through the outer bottom surface.

2. The substrate support assembly of claim 1, further comprising: a heater disposed in the interior of the body; and an HV ESC electrode disposed in the interior of the body.

3. The substrate support assembly of claim 2, wherein each of the heater, the RF electrode, the HV ESC electrode are disposed on parallel layers in the body.

4. The substrate support assembly of claim 3, wherein the body is made of aluminum nitride or aluminum oxide.

5. The substrate support assembly of claim 1, further comprising: a shaft coupled to the outer bottom surface of the body.

6. The substrate support assembly of claim 1, wherein the cylindrical ground electrode is a cage.

7. The substrate support assembly of claim 1, wherein the cylindrical ground electrode is solid continuously along a radius of the cylindrical shape.

8. A method for forming an ESC, the method comprising: sintering an AlN body having a HV ESC electrode and an RF electrode disposed therein, wherein the RF electrode is disposed horizontally in the body; disposing a cylindrical ground electrode along one or more outer surfaces of the sintered AlN body and electrically coupling the cylindrical ground electrode to the RF electrode; enclosing the ground electrode and the sintered body with a dielectric material to form an ESC body; and joining the dielectric material with the ESC body to form the ESC.

9. The method of claim 8, wherein the cylindrical ground electrode is continuous along a radius of the ESC body, and a coaxial ground return is additionally provided to the ground electrode.

10. The method of claim 8, wherein the cylindrical ground electrode is a vertical cage shape disposed in the ESC body.

11. The method of claim 8, further comprising: attaching a metal ground tube to the cylindrical ground electrode, wherein the metal ground tube is disposed in a tube seat attached to the ESC body. ​ ​

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