Process shield, process kit, and process chamber for a pvd process

Abstract

This document provides embodiments of a processing shield used in a processing chamber. In some embodiments, the processing shield used in a processing chamber includes: an annular body having an upper portion and a lower portion, the lower portion extending downward and radially inward from the upper portion, wherein the upper portion includes a plurality of annular grooves on an upper surface of the upper portion and has a plurality of slots disposed between the plurality of annular grooves for fluid coupling of the plurality of annular grooves, and one or more inlets extending from an outer surface of the annular body to an outermost groove of the plurality of annular grooves.

Description

[Technical Field]

[0001] The embodiments of this disclosure are generally related to substrate processing facilities. [Previous Technology]

[0002] A plasma processing chamber typically includes a substrate support for supporting the substrate and a target disposed relative to the substrate support. The target provides a source of material for sputtering onto the substrate during processing. RF power is supplied to the plasma processing chamber to generate plasma in a processing volume disposed between the target and the substrate support. The plasma processing chamber typically includes a processing kit for protecting the chamber walls from unwanted deposition and for confining the plasma. The processing kit generally includes a processing shield. The space between the target and the processing shield is called the dark space. During substrate processing for high-voltage processing (>100 mTorr), contaminants (e.g., exhaled particles) may flow into the dark space, causing unwanted arcing.

[0003] Therefore, the inventors have provided an improved processing kit for use in plasma processing chambers. [Summary of the Invention]

[0004] This document provides embodiments of a processing shield used in a processing chamber. In some embodiments, the processing shield used in a processing chamber includes: an annular body having an upper portion and a lower portion, the lower portion extending downward and radially inward from the upper portion, wherein the upper portion includes a plurality of annular grooves on an upper surface of the upper portion and has a plurality of slots disposed between the plurality of annular grooves for fluid coupling of the plurality of annular grooves, wherein one or more inlets extend from an outer surface of the annular body to an outermost groove of the plurality of annular grooves.

[0005] In some embodiments, a processing kit used in a processing chamber includes: a processing shield having an upper portion and a lower portion, the lower portion extending downward and radially inward from the upper portion, wherein the upper portion includes a plurality of annular grooves on an upper surface of the upper portion and has a plurality of slots disposed between the plurality of annular grooves to fluidly couple the plurality of annular grooves, wherein one or more inlets extend from an outer surface of the processing shield to an outermost groove of the plurality of annular grooves; and a cover ring having an annular body disposed on the processing shield.

[0006] In some embodiments, the processing chamber includes: a chamber body having an internal volume therein; a substrate support disposed in the internal volume; a target disposed in the internal volume relative to the substrate support to at least partially define a processing volume between the target and the substrate support; a processing shield disposed around the substrate support and the target to define an outer boundary of the processing volume, wherein the processing shield and the target define a dark space gap between the processing shield and the target, and wherein the processing shield includes a plurality of annular grooves having a plurality of slots disposed between the plurality of annular grooves to fluidly couple the plurality of annular grooves to the dark space gap; and an isolator ring disposed between the target and the processing shield.

[0007] Other and further embodiments of this disclosure are described below.

Implementation Method

[0014] This document provides embodiments of a treatment kit for use in a treatment chamber. The treatment kit includes a treatment shield disposed around a target within the treatment chamber to prevent unwanted deposition of target material on the chamber walls. The space between the target and the treatment shield is referred to as a dark space. Embodiments of the treatment shield provided herein advantageously include a plurality of gas channels for flowing gas through the gas channels into the dark space, creating a gas screen that prevents contaminants from flowing into the dark space and causing unwanted arcing. The gas may be a flushing gas or one or more treatment gases. When the gas includes one or more treatment gases, the plurality of gas channels advantageously provides improved uniformity of gas distribution entering the treatment chamber.

[0015] FIG1 depicts a schematic side view of a processing chamber 100 (e.g., a plasma processing chamber) having a processing kit according to at least some embodiments of the present disclosure. In some embodiments, the processing chamber 100 is a PVD (physical vapor deposition) processing chamber for reactive processing. However, other types of processing chambers configured for different processes may also be used or modified for embodiments of the processing kit described herein.

[0016] The processing chamber 100 is a vacuum chamber, adapted to maintain a pressure below atmospheric pressure within the internal volume 120 during substrate processing. In some embodiments, the processing chamber 100 is adapted to perform substrate processing at pressures from about 1 mTorr to about 400 mTorr. In some embodiments, the processing chamber 100 is adapted to perform substrate processing at pressures from about 150 mTorr to about 350 mTorr. The processing chamber 100 includes a chamber body 106 covered by a cover assembly 104, which encloses a processing volume 119 located in the upper half of the internal volume 120. The chamber body 106 and the cover assembly 104 may be made of metal, such as aluminum. The chamber body 106 may be grounded via coupling to a ground 115.

[0017] A substrate support 124 is disposed within an internal volume 120 to support and hold a substrate 122, such as a semiconductor wafer, or other electrostatically retainable substrate. The substrate support 124 may generally include an electrostatic clamp 150 disposed on a base 136 and a hollow support shaft 112 for supporting the base 136 and the electrostatic clamp 150. The electrostatic clamp 150 includes a dielectric plate having one or more electrodes 154 disposed therein. The base 136 is generally made of metal, such as aluminum. The base 136 is biasable and can be maintained at an electrically floating potential or grounded during plasma operation. The hollow support shaft 112 provides conduits to supply the electrostatic clamp 150 with, for example, backside gas, process gas, fluid, coolant, power, etc.

[0018] In some embodiments, the hollow support shaft 112 is coupled to a lifting mechanism 113 (e.g., an actuator or motor) to provide vertical movement of the electrostatic clamp 150 between an upper processing position (shown in FIG. 1) and a lower conveying position (not shown). A bellows assembly 110 is disposed around the hollow support shaft 112 and coupled between the electrostatic clamp 150 and the bottom surface 126 of the processing chamber 100 to provide a flexible seal that allows vertical movement of the electrostatic clamp 150 while preventing pressure loss from within the processing chamber 100. The bellows assembly 110 also includes a lower bellows flange 164 that contacts an O-ring 165 or other suitable sealing element that contacts the bottom surface 126 to help prevent pressure loss within the chamber.

[0019] The hollow support shaft 112 provides a conduit for coupling the clamp power supply 140 and RF sources (e.g., RF power supply 174 and RF bias power supply 117) to the electrostatic clamp 150. In some embodiments, the RF power supply 174 and RF bias power supply 117 are coupled to the electrostatic clamp 150 via their respective RF matching networks (RF matching network 116 is shown only). In some embodiments, the substrate support 124 may alternatively include AC or DC bias power.

[0020] The substrate lifter 130 may include a lifting pin 109 mounted on a platform 108, the platform 108 being connected to a shaft 111 coupled to a second lifting mechanism 132 for raising and lowering the substrate lifter 130, such that the substrate 122 may be placed on or removed from the electrostatic clamp 150. The platform 108 may be in the form of a ring lifter. The electrostatic clamp 150 may include a through-hole for receiving the lifting pin 109. A bellows assembly 131 is coupled between the substrate lifter 130 and the bottom surface 126 to provide a flexible seal that maintains chamber pressure during vertical movement of the substrate lifter 130.

[0021] A target 138 is disposed in a processing volume 119 relative to a substrate support 124 to at least partially define the processing volume 119 therebetween. The substrate support 124 has a support surface having a plane substantially parallel to the sputtering surface of the target 138. In some embodiments, the target 138 is made of titanium, tantalum, or aluminum. The target 138 is connected to one or both of a DC power source 190 and / or an RF power source 174. The DC power source 190 may apply a bias voltage to the target 138 relative to the processing shield 105.

[0022] The target 138 includes a sputtering plate 142 mounted to a backplate 144. The sputtering plate 142 includes material to be sputtered onto the substrate 122. The backplate 144 is made of a metal, such as stainless steel, aluminum, copper-chromium, or copper-zinc. The backplate 144 may be made of a material with sufficiently high thermal conductivity to dissipate heat generated in the target 138, which is formed by eddies appearing in the sputtering plate 142 and the backplate 144, as well as by high-energy ions from the generated plasma bombarding the sputtering plate 142. In some embodiments, the backplate 144 includes a recess 146 on one side relative to the sputtering plate 142.

[0023] In some embodiments, the processing chamber 100 includes a magnetic field generator 156 to form a magnetic field around the target 138 to improve sputtering of the target 138. The magnetic field generator 156 can enhance capacitively generated plasma, wherein, for example, a plurality of magnets 151 (e.g., permanent magnets or electromagnetic coils) can provide a magnetic field in the processing chamber 100 to have a rotating magnetic field having an axis of rotation perpendicular to the plane of the substrate 122. Alternatively, the processing chamber 100 may include a magnetic field generator 156 that generates a magnetic field near the target 138 to increase the ion density in the processing volume 119, thereby improving sputtering of the target material. A plurality of magnets 151 may be disposed in a cavity 153 in the cap assembly 104. A coolant (e.g., water) may be disposed in or circulated through the cavity 153 to cool the target 138.

[0024] The processing chamber 100 includes a processing kit 102 surrounding various chamber components to prevent unwanted reactions between these components and the ionized processing material. The processing kit 102 includes a processing shield 105 surrounding the substrate support 124 and the target 138 to at least partially define the processing volume 119. For example, the processing shield 105 may define the outer boundary of the processing volume 119. The outer peripheral surface of the target 138 and the processing shield 105 define a dark space gap 194 therebetween. The dark space gap 194 is configured to prevent arcing between the target 138 and the processing shield 105. In some embodiments, the processing shield 105 is made of metal, such as aluminum. In some embodiments, the processing kit 102 includes a deposition ring 170 disposed on the outer edge of the electrostatic clamp 150. In some embodiments, the processing kit 102 includes a cover ring 180 disposed on the processing shield 105 to form a tortuous gas flow path therebetween.

[0025] The processing chamber 100 is coupled to and in fluid communication with a vacuum system 184, which includes a throttle valve (not shown) and a pump (not shown) for discharging the processing chamber 100. The pressure inside the processing chamber 100 can be regulated by adjusting the throttle valve and / or the pump. A slit valve 148 is coupled to the chamber body 106 and aligned with an opening in the sidewall of the chamber body 106 to facilitate the transfer of the substrate 122 in and out of the chamber body 106.

[0026] Processing chamber 100 is coupled to a first gas supply 192, which is configured to supply one or more gases through processing shield 105 and into dark space gap 194 to advantageously create a gas screen, preventing venting from substrate 122 into dark space gap 194 during processing and causing unwanted arcing. The first gas supply 192 may supply rinsing gas or one or more processing gases. In some embodiments, the first gas supply 192 may supply nitrogen, argon, or oxygen. In some embodiments, processing chamber 100 may also be coupled to and in fluid communication with a second gas supply 118, which may supply one or more processing gases from the lower portion of chamber body 106 (i.e., below substrate 122) to processing chamber 100 for processing substrate 122 disposed therein. For example, the first gas supply 192 may provide nitrogen or oxygen, while the second gas supply 118 may provide argon.

[0027] In use, when the DC power source 190 supplies power to the target 138 and other chamber components connected to the DC power source 190, the RF power source 174 energizes the sputtering gas (e.g., from the first gas supply 192 or the second gas supply 118) to form a plasma of the sputtering gas. The formed plasma impacts and bombards the sputtering surface of the target 138 to sputter material from the target 138 onto the substrate 122. In some embodiments, the frequency range of the RF energy supplied by the RF power source 174 may be from about 2 MHz to about 60 MHz, or, for example, non-limiting frequencies such as 2 MHz, 13.56 MHz, 27.12 MHz, or 60 MHz may be used. In some embodiments, a plurality of RF power sources (i.e., two or more) may be provided to provide RF energy at a plurality of the aforementioned frequencies. Additional RF power sources (e.g., RF bias power source 117) may also be used to supply a bias voltage to the substrate support 124 to attract ions from the plasma toward the substrate 122.

[0028] FIG2 depicts a portion of a processing chamber having a processing kit according to at least some embodiments of the present disclosure. The processing kit 102 includes a processing shield 105, which generally has an annular body 202, including an upper portion 206 and a lower portion 208 extending downward and radially inward from the upper portion 206. In some embodiments, the upper portion 206 includes a coolant channel 230 to circulate coolant through the coolant channel 230 to cool the processing shield 105.

[0029] An isolator ring 210 is disposed between the target 138 and the processing shield 105. In some embodiments, the upper surface 212 of the upper portion 206 includes a recess 228 for receiving the isolator ring 210. In some embodiments, the upper portion 206 includes a plurality of annular grooves 204 on the upper surface 212 of the upper portion 206. In some embodiments, the plurality of annular grooves 204 extend downward from the recess 228. In some embodiments, the upper portion 206 includes radially outward O-ring grooves 232 of the plurality of annular grooves 204 to receive an O-ring 238 or other suitable sealing gaskets to provide a seal between the isolator ring 210 and the processing shield 105.

[0030] The processing shield 105 includes one or more inlets 218 extending from the outer surface 214 of the processing shield 105 to the outermost recess 220 of a plurality of annular recesses 204. One or more inlets 218 are fluidly coupled to a first gas supply 192 to supply gas from the first gas supply 192 to the plurality of annular recesses 204. The processing shield 105 includes a plurality of slots (discussed below with reference to FIG3) to fluidly couple the plurality of annular recesses 204 and provide a gas flow path from one or more inlets 218 to the innermost recess 222.

[0031] In some embodiments, the plurality of annular grooves 204 include a second groove 224 and a third groove 226 disposed between the outermost groove 220 and the innermost groove 222. In some embodiments, each groove in the plurality of annular grooves 204 has a width of about 0.05 inches to about 0.2 inches. In some embodiments, each groove in the plurality of annular grooves 204 has a depth of about 0.3 inches to about 0.4 inches. Although FIG. 2 depicts a plurality of annular grooves 204 including four grooves, the plurality of annular grooves 204 may include more than four grooves or fewer than four grooves. In some embodiments, all grooves in the plurality of annular grooves 204, except for the innermost groove 222, are disposed directly below the isolator ring 210. In some embodiments, all grooves in the plurality of annular grooves 204 have substantially similar widths and depths. In some embodiments, substantially similar or within about 10%.

[0032] FIG3 depicts a schematic top view of a processing shield 105 according to at least some embodiments of the present disclosure. A first gas supply 192 is fluidly coupled to one or more inlets 218. In some embodiments, one or more inlets 218 include four inlets extending to the outermost recess 220. The processing shield 105 includes a plurality of slots 306 between each of the plurality of annular recesses 204 to fluidly couple the outermost recess 220 to the innermost recess 222. In some embodiments, the inner ring 250 of the processing shield 105, which is radially inwardly disposed in the innermost recess 222, has a continuous surface facing the processing volume.

[0033] In some embodiments, a plurality of slots 306 are arranged such that they provide substantially equal flow paths from one or more inlets 218 to the innermost recess 222. In some embodiments, the number of slots 306 between adjacent annular recesses of the plurality of annular recesses 204 increases from the outermost recess 220 to the innermost recess 222. In some embodiments, the number of slots 306 between adjacent annular recesses of the plurality of annular recesses 204 from the outermost recess 220 to the innermost recess 222 is doubled.

[0034] For example, in some embodiments, a plurality of slots 306 include eight slots between the outermost recess 220 and the second recess 224. In some embodiments, the eight slots between the outermost recess 220 and the second recess 224 are arranged at regular intervals. In some embodiments, a plurality of slots 306 include 16 slots between the second recess 224 and the third recess 226. In some embodiments, the 16 slots between the second recess 224 and the third recess 226 are arranged at regular intervals. In some embodiments, a plurality of slots 306 include 32 slots between the third recess 226 and the innermost recess 222. In some embodiments, the 32 slots between the third recess 226 and the innermost recess 222 are arranged at regular intervals.

[0035] Referring back to FIG2, a first gap 240 is disposed between the inner surface of the isolator ring 210 and the outer surface of the inner ring 250 of the upper portion 206 (i.e., the opposing surface of the treatment shield 105). The first gap 240 is fluidly coupled to the innermost recess 222. For example, the first gap 240 may be disposed above the innermost recess 222 such that at least a portion of the bottom opening of the first gap 240 coincides with at least a portion of the top opening of the innermost recess 222. In some embodiments, the width of the first gap 240 is less than the width of the innermost recess 222. In some embodiments, the first gap is about 0.02 inches to about 0.1 inches. A second gap 242 is disposed between the upper surface of the inner ring 250 and the target 138. A dark space gap 194 is disposed between the inner surface of the inner ring 250 and the target 138. The flow path extends from the first gas supply 192 through one or more inlets 218, through a plurality of annular grooves 204, through a first gap 240, through a second gap 242, through a dark space gap 194, and into the processing volume 119. The first gap 240 is maintained at a substantially uniform distance around the processing shield 105 to advantageously provide a more uniform gas distribution into the processing volume 119, and thus a more uniform mixing of the gas supplied by the first gas supply 192 and the target material. In embodiments where the width of the first gap 240 is less than the width of the innermost groove 222, the first gap 240 provides flow restriction to advantageously provide a more uniform gas distribution into the processing volume 119, and thus a more uniform mixing of the gas supplied by the first gas supply 192 and the target material.

[0036] In some embodiments, the lower portion 208 includes a first leg 244 extending downward from the upper portion 206. In some embodiments, the lower portion 208 includes a first ledge 246 extending radially inward from the first leg 244. In some embodiments, the lower portion 208 includes an inner lip 248 extending upward from the first ledge 246. In some embodiments, the first leg 244 is not perforated. In some embodiments, the inner lip 248 is not perforated.

[0037] In some embodiments, a cover ring 180 is disposed on the processing shield 105. The cover ring 180 generally includes an annular body 252, with a lower groove 254 on the lower surface of the annular body 252 to receive an inner lip 248. In some embodiments, the inner lip 248 and the lower groove 254 form a tortuous gas flow path. In some embodiments, the upper surface 216 of the cover ring 180 is radially downward and inwardly inclined. The cover ring 180 and the deposition ring 170 form a tortuous gas flow path therebetween.

[0038] FIG4 depicts a portion of a processing chamber having a processing kit according to at least some embodiments of the present disclosure. In some embodiments, one or more centering bushings 410 are coupled to a processing shield 105 to center a cover ring 180 to the processing shield 105. In some embodiments, the cover ring 180 includes an outer leg 416 and an inner leg 426 extending downward from an annular body 252 on either side of a lower groove 254. In some embodiments, the outer leg 416 includes one or more slots 420 for receiving one or more centering bushings 410. In some embodiments, one or more centering bushings 410 include three bushings. In some embodiments, one or more centering bushings 410 are arranged at regular intervals. In some embodiments, one or more centering bushings 410 are coupled to the processing shield 105 via fasteners 430. In some embodiments, one or more centering bushings 410 extend into an opening 450 in a first ledge 246.

[0039] In some embodiments, one or more centering bushings 410 have rounded upper surfaces. In some embodiments, one or more slots 420 have angled sidewalls 424. In some embodiments, the angled sidewalls of one or more slots 420 extend downward and outward at an angle of about 5 degrees to about 15 degrees. The angled sidewalls of one or more slots 420 and the rounded upper surfaces of one or more centering bushings 410 advantageously enable repeatable concentric placement and allow for concentric thermal expansion of the cover ring 180 relative to the processing shield 105. In some embodiments, one or more centering bushings 410 have a diameter of about 0.3 to about 0.5 inches to advantageously minimize disruption of the tortuous gas flow path between the processing shield 105 and the cover ring 180.

[0040] Although the foregoing describes embodiments of the present disclosure, other and further embodiments of the present disclosure may be designed without departing from its basic scope. [Simplified Explanation of the Diagram]

[0008] The embodiments of this disclosure, which are briefly summarized above and discussed in more detail below, can be understood by referring to the illustrative embodiments of this disclosure depicted in the accompanying drawings. However, the drawings only illustrate typical embodiments of this disclosure and should therefore not be considered as limiting the scope, as other equivalent embodiments of this disclosure are permissible.

[0009] FIG1 depicts a schematic side view of a processing chamber having a processing kit according to at least some embodiments of the present disclosure.

[0010] Figure 2 depicts a schematic top view of a processing shield according to at least some embodiments of the present disclosure.

[0011] FIG3 depicts a cross-sectional side view of a portion of a processing chamber having a processing kit according to at least some embodiments of the present disclosure.

[0012] FIG4 depicts a cross-sectional side view of a portion of a processing chamber having a processing kit according to at least some embodiments of the present disclosure.

[0013] For ease of understanding, the same reference numerals are used where possible to denote common elements in the drawings. The drawings are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. [Biomaterial Storage]

[0042] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A processing shield for use in a processing chamber, comprising: An annular body having an upper portion and a lower portion, the lower portion extending downward and radially inward from the upper portion, wherein the upper portion includes a plurality of annular grooves on an upper surface and has a plurality of slots disposed between the plurality of annular grooves for fluid coupling of the plurality of annular grooves, wherein one or more inlets extend from an outer surface of the annular body to an outermost groove of the plurality of annular grooves, and wherein the upper surface of the annular body includes a recess for receiving an isolator ring, and the plurality of annular grooves extend downward from a bottom surface of the recess.

2. The processing shield as described in claim 1, wherein the plurality of slots between adjacent annular grooves of the plurality of annular grooves increases in number from the outermost groove to an innermost groove.

3. The processing shield as described in claim 2, wherein the plurality of annular grooves includes a second groove and a third groove disposed between the outermost groove and the innermost groove, and wherein the plurality of slots includes 8 slots between the outermost groove and the second groove, 16 slots between the second groove and the third groove, and 32 slots between the third groove and the innermost groove.

4. The processing shield as described in Request 1, wherein the one or more entry points include four entry points.

5. The processing shield as described in any one of claims 1 to 4, wherein the upper portion includes a coolant channel.

6. The processing shield as described in any one of claims 1 to 4, wherein the plurality of annular grooves have a width of about 0.05 inches to about 0.2 inches.

7. The processing shield as described in any one of claims 1 to 4, wherein the upper portion includes an O-ring groove radially outward from the plurality of annular grooves.

8. The processing shielding as described in any one of claims 1 to 4, wherein the following portion includes: A first leg extending downward from the upper portion, a first wall frame extending radially inward from the first leg, and an inner lip extending upward from the first wall frame, wherein the first leg does not have a perforation.

9. A processing kit for use in a processing chamber, comprising: A processing shield having an upper portion and a lower portion extending downward and radially inward from the upper portion, wherein the upper portion includes a plurality of annular grooves on an upper surface and has a plurality of slots disposed between the plurality of annular grooves for fluid coupling of the plurality of annular grooves, one or more inlets extending from an outer surface of the processing shield to an outermost groove of the plurality of annular grooves, and an inner ring of the processing shield having a continuous surface facing the processing volume, the innermost groove of the plurality of annular grooves being radially inwardly disposed; and a cover ring having an annular body disposed on the processing shield.

10. The processing kit as described in claim 9 further includes one or more centering bushings coupled to the processing shield to center the cover ring to the processing shield.

11. The processing kit as claimed in claim 10, wherein the cover ring includes an outer leg and an inner leg, the inner leg extending downward from the annular body, and wherein the outer leg includes one or more slots for receiving the one or more centering bushings.

12. The processing kit as described in any one of claims 9 to 11, wherein the one or more centering bushings comprise three bushings.

13. The processing kit as described in any one of claims 9 to 11, wherein the plurality of slots between adjacent annular grooves of the plurality of annular grooves increases in number from the outermost groove to an innermost groove.

14. A processing chamber, comprising: A chamber body having an internal volume within the chamber body; A substrate support disposed within the internal volume; a target disposed within the internal volume relative to the substrate support to at least partially define a processing volume between the target and the substrate support; a processing shield disposed around the substrate support and the target to define an outer boundary of the processing volume, wherein the processing shield and the target define a dark space gap between the processing shield and the target, and wherein the processing shield includes a plurality of annular grooves having a plurality of slots disposed between the plurality of annular grooves to fluidly couple the plurality of annular grooves to the dark space gap; and an isolator ring disposed between the target and the processing shield, wherein a gas flow path extends between an inner sidewall of the isolator ring and an outer sidewall of the processing shield adjacent to an innermost groove of the plurality of annular grooves.

15. The processing chamber as claimed in claim 14, further comprising a first gas supply for flowing one or more gases through the plurality of annular grooves to the dark space gap.

16. The processing chamber as claimed in claim 14, further comprising a cover ring and one or more centering bushings, the cover ring being disposed on the processing shield, the one or more centering bushings being coupled to the processing shield to center the cover ring to the processing shield.

17. The processing chamber as claimed in any one of claims 14 to 16, wherein the processing shield includes a recess on an upper surface of the processing shield, wherein the plurality of annular grooves extend from the recess, and wherein the isolator ring is disposed in the recess.

18. The processing chamber as claimed in any one of claims 14 to 16, wherein the processing shield includes a coolant passage configured to allow coolant to flow through the coolant passage.

19. The processing chamber as described in any one of claims 14 to 16, wherein a gap between an inner surface of the isolator ring and an opposing surface of the processing shield is about 0.02 inches to about 0.1 inches.

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