Porous plug for gas supply in electrostatic chuck

Abstract

Provided herein is a porous plug for gas delivery in a substrate support, and a substrate support and a substrate processing chamber incorporating the same. In some embodiments, the porous plug used in the substrate support includes a porous central passage and a solid shell that is coupled to and surrounds the porous central passage such that there is no continuous gap between the porous central passage and the solid shell along the entire length of the porous plug, the solid shell including a sealing surface disposed at an end of the solid shell to facilitate the formation of a seal surrounding the porous central passage along the sealing surface. In some embodiments, one or more O-ring retaining grooves may be formed around the outer surface of the solid shell.

Description

[Technical Field]

[0001] TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to substrate processing apparatus, and more particularly to a substrate support having a gas supply in a substrate processing apparatus. [Background technology]

[0002]

[0002] In the semiconductor industry, devices are fabricated by a number of manufacturing processes, such as etching and deposition, and the size of the structures produced is ever decreasing. The etching and deposition processes are performed on a substrate in a processing chamber having a substrate support, such as an electrostatic chuck. The inventors have observed that as the voltage of high-power electrostatic chucks increases, the components of the electrostatic chuck, such as the gas delivery components, become more vulnerable to arcing.

[0003] Accordingly, the present inventors have provided an improved porous plug that can significantly reduce arcing. Summary of the Invention

[0004]

[0004] Provided herein are porous plugs for gas distribution in substrate supports, as well as substrate supports and substrate processing chambers incorporating the same. In some embodiments, the porous plug used in a substrate support includes a porous central passage and a solid outer shell coupled to and surrounding the porous central passage such that there is no continuous gap between the porous central passage and the solid outer shell along the entire length of the porous plug, the solid outer shell including sealing surfaces disposed at the ends of the solid outer shell to promote formation of a seal surrounding the porous central passage along the sealing surfaces. In some embodiments, one or more O-ring retention grooves may be formed around the outer surface of the solid outer shell.

[0005]

[0005] In some embodiments, a substrate support is provided, the substrate support including: a plurality of layers including a first electrode and a second electrode separated by an insulator plate; a backside gas channel formed through the plurality of layers, the backside gas channel including a plug opening formed in at least the insulator plate; a porous plug disposed in the plug opening, the porous plug having a porous central passage aligned with the backside gas channel to promote backside gas flow therethrough; a solid outer shell coupled to the porous central passage and surrounding the porous central passage such that there is no continuous gap between the porous central passage and the solid outer shell along the entire length of the porous plug, the solid outer shell including a sealing surface disposed at an end of the solid outer shell to promote formation of a seal surrounding the porous central passage along the sealing surface; and an O-ring disposed between the sealing surface adjacent the plug opening and one of the plurality of layers.

[0006] In some embodiments, the porous plug in the substrate support is a first porous plug, and the substrate support further includes a second porous plug disposed in the second plug opening, the second porous plug including a porous central passage aligned with the first porous plug and aligned with the backside gas channel to facilitate backside gas flow therethrough, a solid outer shell coupled to the porous central passage and surrounding the porous central passage such that there is no continuous gap between the porous central passage and the solid outer shell along the entire length of the second porous plug, the solid outer shell including a sealing surface disposed at an end of the solid outer shell to facilitate formation of a seal surrounding the porous central passage along the sealing surface, and an O-ring disposed between the sealing surfaces of the first porous plug and the second porous plug. In some embodiments, the substrate support may be an electrostatic chuck.

[0007]

[0007] In some embodiments, a processing chamber is provided, the processing chamber including a chamber body and a lid surrounding an internal region, a substrate support disposed in the internal region, and a porous plug described in any of the embodiments disclosed herein.

[0008]

[0008] Other further embodiments of the present disclosure are described below.

[0009]

[0009] The embodiments of the present disclosure summarized above and described in more detail below can be understood by reference to the exemplary embodiments of the present disclosure illustrated in the accompanying drawings. However, the accompanying drawings depict only typical embodiments of the present disclosure and therefore should not be considered limiting in scope, as the present disclosure may admit of other equally effective embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a semiconductor processing chamber having a plasma prevention device in accordance with at least some embodiments of the present disclosure. [Figure 2] FIG. 1 is a partial schematic side view of an electrostatic chuck having a porous plug, in accordance with at least some embodiments of the present disclosure. [Figure 3] FIG. 1 is a partial schematic side view of an electrostatic chuck having a porous plug, in accordance with at least some embodiments of the present disclosure. [Figure 4] FIG. 1 is a partial schematic side view of an electrostatic chuck having a porous plug, in accordance with at least some embodiments of the present disclosure. [Figure 5] 1A-D are partial schematic side views, respectively, of an electrostatic chuck having a porous plug, according to at least some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0015] To facilitate understanding, the same reference numerals have been used, wherever possible, to designate identical elements common to the drawings. The drawings 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.

[0012]

[0016] Embodiments of the present disclosure generally relate to porous plugs and their use in substrate supports suitable for preventing or limiting undesired arcing during use in a processing chamber. The inventors have observed that porous plugs are particularly useful for processing in high plasma power regions. For example, the inventors have observed that as voltages increase in high-power electrostatic chucks, certain parts of the system become more vulnerable to arcing. Accordingly, the inventors have provided an improved porous plug for use in a substrate support that advantageously allows for backside gas to be supplied to a high-voltage electrostatic chuck without arcing or plasma ignition along the path from the high voltage to ground, thereby allowing for the application of high voltages to the electrostatic chuck without failure.

[0013]

[0017] 1 is a cross-sectional view of one embodiment of a semiconductor processing chamber 100 having a porous plug disposed within a substrate support, according to at least some embodiments of the present disclosure. The processing chamber 100 includes a chamber body 102 and a lid 104 that enclose an interior region 106. The processing chamber 100 depicted in FIG. 1 is exemplary and not limiting of the present disclosure, as the porous plugs described herein can be used with many different substrate supports and / or processing chambers having other configurations where arcing within the substrate support is a concern.

[0014]

[0018] The chamber body 102 is typically fabricated from aluminum, stainless steel, or other suitable material. The chamber body 102 generally includes chamber walls (e.g., sidewalls 108) and a bottom 110 that at least partially define an interior region 106 of the processing chamber 100. To facilitate entry and exit of a substrate 144 from the processing chamber 100, a substrate access port (not shown) is generally defined in the sidewalls 108 and selectively sealed by a slit valve.

[0015]

[0019] One or more liners may be disposed in the interior region 106 of the chamber body 102. For example, an outer liner 116 may be disposed against or on the sidewall 108 of the chamber body 102. The outer liner 116 may be made of aluminum oxide and / or may be coated with a plasma- or halogen-containing gas-resistant material, such as yttria, yttria alloys, or oxides thereof, such as YO.

[0016]

[0020] A window 112 may be formed within the processing chamber 100 to facilitate process monitoring and control, for example, via optical emission spectroscopy (OES) or other techniques that require viewing into the interior region 106 of the processing chamber 100. For example, the window 112 may be formed through the sidewall 108 and a liner (e.g., the outer liner 116). A stray plasma preventer may be positioned between the sidewall 108 and the outer liner 116 adjacent the window 112 to prevent plasma ignition therebetween.

[0017]

[0021] An exhaust port 126 is defined in the chamber body 102 and couples the interior region 106 to a pumping system 128. The pumping system 128 generally includes one or more pumps and a throttle valve used to evacuate and regulate the pressure in the interior region 106 of the processing chamber 100. In one embodiment, the pumping system 128 maintains the pressure within the interior region 106.

[0018]

[0022] The lid 104 is sealably supported on a sidewall 108 of the chamber body 102. The lid 104 can be opened to allow access to the interior region 106 of the processing chamber 100. The lid 104 may optionally include a window 142 to facilitate optical process monitoring. In one embodiment, the window 142 is constructed of quartz or other suitable material that allows transmission of signals utilized by the optical monitoring system 140.

[0019]

[0023] A gas panel 158 is coupled to the processing chamber 100 to supply process and / or cleaning gases to the interior region 106. Examples of process gases can include halogen-containing gases such as C2F6, SF6, SiCl4, HBr, NF3, CF4, Cl2, CHF3, CF4, and SiF4, among others, and other gases such as O2 or N2O. Examples of carrier gases include N2, He, Ar, and other gases inert to the process, non-reactive gases. An inlet port 132', and optional 132" is provided in the lid 104 to allow gases to be supplied from the gas panel 158 through the gas distribution assembly 130 to the interior region 106 of the processing chamber 100.

[0020]

[0024] The gas distribution assembly 130 is coupled to the inner surface 114 of the lid 104. The gas distribution assembly 130 includes a gas distribution plate 194. The gas distribution assembly 130 includes a plenum 127 defined between the lid 104 and the gas distribution plate 194. The gas distribution plate 194 may be coupled to or include a conductive base plate 196. The conductive base plate 196 may function as an RF electrode. The gas distribution plate 194 may be a flat disk with a plurality of apertures 134 formed in its lower surface facing the substrate 144. The gas distribution plate 194 may also include a portion 138 corresponding to the window 142. The portion 138 may be made of a similar material to the window 142 to facilitate optical process monitoring. The apertures 134 allow gas to flow from the inlet ports 132 (shown as 132′, 132″) through the plenum 127, out of the apertures 134, into the interior region 106 of the processing chamber 100, and in a predetermined distribution across the surface of a substrate 144 being processed in the processing chamber 100.

[0021]

[0025] A substrate support assembly 148 is positioned in the interior region 106 of the processing chamber 100 below the gas distribution assembly 130. The substrate support assembly 148 holds the substrate 144 during processing. An edge deposition ring 146 is sized to accept the substrate 144 thereon while protecting the substrate support assembly 148 from the plasma and deposition materials. An inner liner 118 may be coated around the periphery of the substrate support assembly 148. The inner liner 118 may be a halogen-containing gas resistant material substantially similar to the material used for the outer liner 116. In one embodiment, the inner liner 118 may be made of the same material as the outer liner 116.

[0022]

[0026] In one embodiment, the substrate support assembly 148 includes a mounting plate 162, a base 164, and an electrostatic chuck 166. The mounting plate 162 is coupled to the bottom 110 of the chamber body 102 and includes passages for routing utilities such as fluids, power lines, sensor leads, etc. to the base 164 and the electrostatic chuck 166, among other things.

[0023]

[0027] In some embodiments, at least one of the base 164 or the electrostatic chuck 166 may include at least one optional embedded heater 176 and a plurality of conduits 170 to control the lateral temperature profile of the substrate support assembly 148. The conduits 170 are fluidly coupled to a fluid source 172 that circulates a temperature-regulating fluid therethrough. The heaters 176 are regulated by a power supply 178. The conduits 170 and the heaters 176 are used to control the temperature of the base 164, and therefore heat and / or cool the electrostatic chuck 166.

[0024]

[0028] The electrostatic chuck 166 includes at least one clamping electrode 180 controlled using a chucking power supply 182. In some embodiments, the electrode 180 may be further coupled to one or more RF power sources 184 through a matching network 188 for maintaining a plasma formed from process and / or other gases within the processing chamber 100. The RF power sources 184 are generally capable of generating RF signals having frequencies from about 50 kHz to about 3 GHz and powers up to about 10,000 Watts. Gases entering the interior region 106 of the processing chamber 100 may be energized by the RF electrodes to maintain a plasma within the interior region 106. While described as having one or more RF sources coupled to the electrostatic chuck 166, the one or more RF sources may alternatively or additionally be coupled to a conductive base plate 196 or any other electrode located in or adjacent to the lid 104.

[0025]

[0029] The substrate support assembly 148 further includes one or more channels extending through the substrate support assembly 148 to the support surface of the electrostatic chuck 166 for supplying a backside gas, such as helium, from a backside gas source 174 to the region between the backside of the substrate 144 and the support surface of the electrostatic chuck 166. The one or more channels extend between various layers of the substrate support assembly 148, including layers having different potentials. The inventors have observed that arcing can occur between two electrodes having different potentials within the substrate support (e.g., between a powered electrode and a ground electrode).

[0026]

[0030] While substrate support assemblies 148 having exemplary configurations are described above, the porous plugs described herein may be provided more generally at one or more locations along the backside gas channel to minimize or prevent arcing in the backside gas channel. The porous plug advantageously facilitates the delivery of backside gas (e.g., helium) to a high-voltage substrate support (e.g., an electrostatic chuck) with reduced or no arcing or plasma ignition along the path from the high voltage to ground, thereby advantageously enabling the application of high voltage to the substrate support without failure.

[0027]

[0031] For example, Figure 2 is a partial schematic side view of a substrate support 202 having a porous plug 200, according to at least some embodiments of the present disclosure. The substrate support 202 can be used as the substrate support assembly 148 described above with respect to Figure 1. The substrate support 202 generally includes a stack of multiple layers, such as a grounded plate 204 (e.g., a first electrode), an insulator plate 206 disposed on the grounded plate 204, a conductive base plate 208 (e.g., a second electrode) disposed on the insulator plate 206, and a dielectric layer 212 (e.g., an electrostatic chuck) disposed on the insulator plate 206. The dielectric layer 212 can be bonded to the insulator plate 206 via a bonding layer 210. The dielectric layer 212 includes one or more electrodes 216, such as a mesh electrode, disposed therein to facilitate electrostatically holding a substrate 214 (e.g., a semiconductor wafer, etc.) on the substrate support 202 during processing in a processing chamber.

[0028]

[0032] To facilitate the delivery of backside gas (e.g., from the backside gas source 174 described with respect to FIG. 1 ) to the region between the backside of the substrate 214 and the support surface of the dielectric layer 212, one or more backside gas conduits may be formed through various layers of the substrate support 202. For example, as shown in FIG. 2 , the backside gas conduit is formed by a channel 218 formed through the ground plate 204, a plug opening 232 formed through the insulator plate 206 to receive the porous plug 200, and a channel 220 formed through the base plate 208, the bonding layer 210, and the dielectric layer 212. As indicated by the arrows in FIG. 2 , backside gas may be delivered through the substrate support 202 to the support surface of the dielectric layer 212. While illustrated as being formed vertically through the various layers of the substrate support 202, the backside gas conduit may alternatively or in combination have sections that extend laterally through one or more layers of the substrate support and / or may branch from a single input to multiple outputs.

[0029]

[0033] The porous plug 200 is disposed in a backside gas conduit, for example, in a plug opening 232 formed through the insulator plate 206. The porous plug generally has the same shape as the plug opening 232. The plug opening 232 and the porous plug 200 may generally be any shape, and in some embodiments are cylindrical for ease of manufacturing and to minimize sharp corners.

[0030]

[0034] The porous plug 200 includes a porous central passage 222 and a solid or non-porous outer shell (solid outer shell 224). The porous central passage 222 is bonded to the solid outer shell 224 such that there is no continuous gap therebetween along the entire length of the porous plug 200 (e.g., from top to bottom).

[0031]

[0035] The porous central passage 222 may be made of a suitable material, such as a ceramic, e.g., aluminum oxide. The porous central passage 222 may have a pore size ranging from about 5 μm to about 500 μm. However, smaller or larger pore sizes can be used as needed for a particular application. For example, in higher voltage applications than currently used, even smaller pore sizes may be useful. The porous central passage 222 may generally be any shape, and in some embodiments, is cylindrical. In some embodiments, the porous central passage 222 has a diameter of about 1 / 16 inch to about 3 / 4 inch.

[0032]

[0036] The solid shell 224 may be made of a suitable material, such as a ceramic, e.g., aluminum oxide. The solid shell 224 may generally be any shape, and in some embodiments is cylindrical. In some embodiments, the solid shell 224 has an outer diameter of about ¼ inch to about 1 inch.

[0033]

[0037] The width of the porous plug 200 is sized to define a small gap 226 between the outer surface of the porous plug 200 and the wall of the plug opening 232. In some embodiments, the distance across the gap 226 is about 1 to about 30 mils (0.001 to about 0.030 inches). The gap 226 advantageously facilitates insertion of the porous plug 200 into the plug opening 232 despite tolerances of either the porous plug 200 or the plug opening 232. The gap 226 also advantageously facilitates movement of different components during heating and cooling cycles due to differences in thermal expansion coefficients, thus minimizing any stresses induced in the components or misalignment of the backside gas flow paths through different layers of the substrate support 202.

[0034]

[0038] The solid shell 224 further includes sealing surfaces 228 on both ends of the solid shell 224 to facilitate forming a seal with an O-ring or other gasket (e.g., O-ring 230 shown in FIG. 2 ) surrounding the porous central passage 222. In some embodiments, the sealing surfaces 228 on the ends of the solid shell 224 have a surface roughness Ra of 16 microinches or less. The width of the sealing surfaces 228 may be sufficient to form a seal with an O-ring or other gasket material disposed against the surface when installed. In some embodiments, the sealing surfaces 228 have a width of about 3 / 32 inch to about 1 / 4 inch. The gasket or O-ring may be any elastomeric material suitable for electrostatic chuck applications.

[0035]

[0039] The inventors have observed that a porous plug without a solid outer shell 224 may fail at the low-pressure interface between the porous material and the insulator plate because gaps must normally exist for mechanical reasons (e.g., tolerances and thermal movement as discussed above). The porous plug disclosed herein, by bonding the porous central passage 222 to the solid outer shell 224, advantageously allows for zero gaps at the low-pressure interface between the porous material and the solid insulator material surrounding it.

[0036]

[0040] In this manner, providing a seal along the edge of solid shell 224 advantageously helps isolate the low-pressure backside gas conduit (e.g., flowing through porous central passage 222) from gap 226, which may be maintained at a higher pressure, such as atmospheric pressure or near atmospheric pressure. Maintaining gap 226 at a higher pressure makes arcing and plasma ignition less likely to occur and further isolates any particulates that may form from any arcing event from reaching the gas conduit and the substrate 214 or interior regions of the processing chamber. For example, any arcing would be forced to travel at atmospheric pressure (e.g., around solid shell 224) rather than at a lower pressure (e.g., through porous central passage 222).

[0037]

[0041] The height of the solid shell 224 (and porous central passage 222) can be determined based on the thermal expansion of the various layers of the substrate support 202 and the compression of the gasket or O-ring. For example, the height can be selected so that when the substrate support 202 expands due to heating, the maximum compression of the O-ring 230 is not exceeded while maintaining a seal. In some embodiments, the height of the solid shell 224 can be from about ½ inch to about 5 inches. The height selected depends on the configuration of the substrate support and the porous plug. In some embodiments, a stack of multiple porous plugs can be provided within the same opening.

[0038]

[0042] 2, a single porous plug 200 is provided in a plug opening 232 formed in insulator plate 206. An O-ring 230 is disposed between lower sealing surface 228 and ground plate 204, and an O-ring 230 is disposed between upper sealing surface 228 and base plate 208.

[0039]

[0043] However, as shown in FIG. 3 , a porous plug 300 similar to the porous plug 200 is provided, except that a first plug 302 is provided with a second plug 304. The first and second plugs 302, 304 are similar to the porous plug 200, except that the first plug is disposed in a plug opening 232 formed in the insulator plate 206 and the second plug 304 is disposed in a plug opening 332 formed in the base plate 208. The first plug 302 is similar to the porous plug 200 described above. The second plug 304 is also similar to the porous plug 200 described above, having a porous central passage 322, a solid outer shell 324, and a sealing surface 328. The second plug 304 is sized to have a gap 326 similar to the gap 226 described above. An additional O-ring 230 is provided between the first plug 302 and the second plug 304 to maintain a seal between the low pressure region (porous central passage 222 and porous central passage 322) and the high pressure region (gap 226 and gap 326).

[0040]

[0044] Alternatively, as shown in Figure 4, a porous plug 400 is provided that is similar to porous plug 200 except that the length of the porous plug 400 is a single plug sized to fit within plug openings 232, 332. Porous plug 400 is similar to porous plug 200 described above, having a porous central passageway 422, a solid outer shell 424, and a sealing surface 428. Porous plug 400 is sized to have a gap 426 similar to gaps 226, 326 described above.

[0041]

[0045] In some embodiments, one or more additional gaskets or O-rings may be provided around the outer sidewall(s) of the porous plug. The additional O-ring(s) on the sides of the porous plug facilitate spacing and alignment of the porous plug within the plug opening, advantageously maintaining a more concentric fit and uniform gap around the porous plug. The additional O-ring(s) may also advantageously help hold the porous plug in place. The additional O-ring(s) may also advantageously help further block line of sight along the gap, further limiting or preventing arcing or plasma ignition in the gap.

[0042]

[0046] For example, FIGS. 5A-5D each illustrate a partially schematic side view of an electrostatic chuck having a porous plug 500 with a side O-ring, according to at least some embodiments of the present disclosure. The porous plug 500 may be any of the porous plugs 200, 300, or 400 described above. The porous plug is disposed in a plug opening formed in one or more of the insulator plate 206 or the base plate 208. As shown in FIG. 5A , in some embodiments, one or more O-rings 504 (two are shown in FIG. 5A ) are disposed around the porous plug 500 in the gap 502 (e.g., gaps 226, 326, and / or 426). In some embodiments, as shown in FIG. 5A , the O-rings may only be disposed around the outer surface of the porous plug 500 (e.g., around the solid shells 224, 324, and / or 424). In some embodiments, as shown in FIG. 5B, a retention groove 506 can be formed around the outer surface of the porous plug 500 (e.g., around the solid shells 224, 324, and / or 424) to help retain the O-ring in a desired position. In some embodiments, as shown in FIG. 5C, a retention groove 508 can be formed along the inner surface of the plug opening (e.g., plug openings 232 and / or 332) to help retain the O-ring in a desired position. In some embodiments, as shown in FIG. 5B, a retention groove 506 can be formed around the outer surface of the porous plug 500 (e.g., around the solid shells 224, 324, and / or 424) to help retain the O-ring in a desired position. In some embodiments, as shown in FIG. 5D, both retention grooves 506 and 508 can be provided to help retain the O-ring in a desired position.

[0043]

[0047] The electrostatic chuck (e.g., dielectric layer 212) may also have a separate porous plug using this or any existing design to further limit or prevent arcing due to voltage differences between the substrate 214 and the base plate 208 or between the electrode 216 and the base plate 208.

[0044]

[0048] While the forgoing 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.

Claims

1. 1. A porous plug for use in a substrate support, comprising: a porous central passage; a solid shell coupled to and surrounding the porous central passage such that there is no continuous gap between the porous central passage and the solid shell along the entire length of the porous plug, the solid shell including sealing surfaces disposed at a top end of the solid shell adjacent a first end of the porous central passage and at an opposing bottom end of the solid shell adjacent a second end of the porous central passage to form a seal surrounding the porous central passage along the sealing surfaces; A porous plug comprising:

2. 10. The porous plug of claim 1, wherein the sealing surface has a surface roughness Ra of 16 microinches or less.

3. 10. The porous plug of claim 1, wherein the porous central passage is made of a ceramic material.

4. A porous plug as described in claim 3, wherein the solid outer shell is made of a ceramic material.

5. The porous plug of claim 1 , wherein the solid shell is made of a ceramic material.

6. the porous central passage has a diameter of 1 / 16 inch to 3 / 4 inch; the solid shell has an outer diameter of ¼ inch to 1 inch; or The sealing surface has a width of 3 / 32 inch to 1 / 4 inch 6. The porous plug of claim 1, wherein the porous plug is at least one of:

7. 6. The porous plug of claim 1, further comprising one or more O-ring retaining grooves formed around an outer surface of the solid shell.

8. 6. The porous plug of claim 1, wherein the height of the porous plug is between 1 / 2 inch and 5 inches.

9. A substrate support, a plurality of layers including a first electrode and a second electrode separated by an insulator plate; a backside gas channel formed through the plurality of layers, the backside gas channel including a plug opening formed in at least the insulator plate; a porous plug as defined in any one of claims 1 to 5, disposed in a plug opening in the substrate support, the porous central passage being aligned with the backside gas channel to facilitate backside gas flow therethrough; an O-ring disposed between the sealing surface and a layer of the plurality of layers adjacent to the plug opening; A substrate support comprising:

10. 10. The substrate support of claim 9, further comprising a gap defined between an opposing surface of the plug opening and the solid shell, the distance measured across the gap being between 0.001 and 0.030 inches.

11. 10. The substrate support of claim 9, wherein the plurality of layers further comprises an electrostatic chuck comprising a dielectric layer coupled to the second electrode and having one or more electrodes disposed within the dielectric layer.

12. the porous plug is a first porous plug, and further comprising: a second porous plug disposed in the second plug opening, the second porous plug including: a porous central passage aligned with the first porous plug and aligned with the backside gas channel to facilitate backside gas flow therethrough; and a solid outer shell coupled to and surrounding the porous central passage such that there is no continuous gap between the porous central passage and the solid outer shell along the entire length of the second porous plug, the solid outer shell including sealing surfaces disposed at ends of the solid outer shell to form a seal surrounding the porous central passage along the sealing surfaces; an O-ring disposed between the sealing surfaces of the first and second porous plugs; The substrate support of claim 9 , comprising:

13. The substrate support of claim 12 , wherein the second plug opening is disposed through the second electrode.

14. The substrate support of claim 9 , wherein the plug opening is disposed through the insulator plate and the second electrode.

15. one or more O-ring retaining grooves formed in one or more of the outer surface of the solid shell or the sidewall of the plug opening; an O-ring disposed in each of the one or more O-ring retaining grooves; The substrate support of claim 9 further comprising:

16. the porous central passage has a diameter of 1 / 16 inch to 3 / 4 inch; The solid shell has an outer diameter of 1 / 4 inch to 1 inch; or The sealing surface has a width of 3 / 32 inch to 1 / 4 inch The substrate support of claim 9 , wherein the substrate support is at least one of:

17. The substrate support of claim 9 , wherein the porous plug has a height of ½ inch to 5 inches.

18. 1. A processing chamber comprising: a chamber body and a lid enclosing an interior region; a substrate support disposed in the interior region, a plurality of layers including a first electrode and a second electrode separated by an insulator plate; a backside gas channel formed through the plurality of layers, the backside gas channel including a plug opening formed in at least the insulator plate; a substrate support including:

6. A porous plug as disclosed in any one of claims 1 to 5, disposed in a plug opening of the substrate support, wherein a porous central passage is aligned with the backside gas channel to facilitate backside gas flow therethrough; an O-ring disposed between the sealing surface and a layer of the plurality of layers adjacent to the plug opening; A processing chamber comprising:

19. the porous plug is a first porous plug, and further comprising: a second porous plug disposed in the second plug opening, the second porous plug including: a porous central passage aligned with the first porous plug and aligned with the backside gas channel to facilitate backside gas flow therethrough; and a solid outer shell coupled to and surrounding the porous central passage such that there is no continuous gap between the porous central passage and the solid outer shell along the entire length of the second porous plug, the solid outer shell including sealing surfaces disposed at ends of the solid outer shell to form a seal surrounding the porous central passage along the sealing surfaces; an O-ring disposed between the sealing surfaces of the first and second porous plugs; 20. The processing chamber of claim 18, comprising:

20. one or more O-ring retaining grooves formed in one or more of the outer surface of the solid shell or the sidewall of the plug opening; an O-ring disposed in each of the one or more O-ring retaining grooves; 20. The processing chamber of claim 19, further comprising:

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