Assembled window for processing chamber

Abstract

A dielectric window assembly for use in a plasma processing chamber is provided. A plasma facing body has a plasma facing surface on a first side of the plasma facing body and a second side opposite the first side, wherein the plasma facing surface comprises yttrium aluminum oxide. A backing plate is on the second side of the plasma facing body. A bond layer comprising an adhesive material bonds the plasma facing body to the backing plate to form the dielectric window assembly.

Description

ASSEMBLED WINDOW FOR PROCESSING CHAMBERCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of U.S. Applications No. 63 / 606,033, filed December 4, 2023 and 63 / 699,996, filed September 27, 2024, which is incorporated herein by reference for all purposes.BACKGROUND

[0002] The background description provided here is for the purpose of generally presenting the context of the disclosure. Information described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0003] The disclosure relates to parts for use in a plasma processing chamber. More specifically, the disclosure relates to a dielectric window that enables transmission of Radio Frequency (RF) power forming a Transformed Coupled Plasma (TCP) in the processing chamber.

[0004] Components of the plasma processing chamber, such as the dielectric window, arc directly exposed to aggressive / corrosive plasma environments, that can cause degradation of the dielectric window. New approaches to dielectric window design & assembly are needed to address industry requirements. Also, as RF power increases, thermal management of the chamber environment becomes more challenging due to the increased heat fluxes from the plasma. This further necessitates new hardware solutions to maintain chamber temperature uniformity while still having robust resistance to plasma degradation. Cooling of the dielectric TCP window in emerging, high-power, thermally-sensitive applications is essential. The TCP window is a large thermal mass that receives much of the plasma heat load. Existing designs for thermal management rely on backside air convection and thermal contact to neighboring chamber components (i.e., pinnacle).SUMMARY

[0005] To achieve the foregoing and in accordance with the purpose of the present disclosure, a dielectric window assembly for use in a plasma processing chamber is provided. A plasma facing body has a plasma facing surface on a first side of the plasma facing body and a second side opposite the first side, wherein the plasma facing surface comprises yttrium aluminum oxide. A backing plate is on the second side of the plasma facing body. A bond layer comprising an adhesive material bonds the plasma facing body to the backing plate to form the dielectric window assembly.

[0006] These and other features of the present disclosure will be described in more detail below in the detailed description and in conjunction with the following figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

[0008] FIG. 1 is a high-level flow chart of a process that may be used in an embodiment.

[0009] FIGS. 2A-C arc schematic cross-scctional side views of a dielectric window component formed in some embodiments.

[0010] FIG. 3A-B are schematic cross-sectional side views of dielectric window components formed in some embodiments.

[0011] FIG. 4 is a cross-sectional top view of a backing plate used in some embodiments.

[0012] FIG. 5 is a schematic view of a plasma processing chamber that is used in an embodiment.

[0013] In the drawings, like reference numerals are sometimes used to designate like structural elements. It should also be appreciated that the depictions in the figures are diagrammatic and not to scale.DETAILED DESCRIPTION

[0014] The present disclosure will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without some or all of these specific details. In other instances, well known process steps and / or structures have not been described in detail in order to not unnecessarily obscure the present disclosure.

[0015] Some components of plasma processing chambers, such as dielectric windows, are exposed to plasma used to process semiconductor devices. Dielectric windows separate the interior of a plasma processing chamber from the exterior of the plasma processing chamber. A coil is placed outside of the dielectric window. Power is transmitted from the coil through the dielectric window to inside the plasma processing chamber. Dielectric windows may be made of aluminum oxide (AI2O3), also called alumina ceramic. Aluminum oxide ceramic has sufficient mechanical strength, thermal uniformity, low loss RF (radio frequency) transmission, a low cost, a high direct current (DC) electrical resistance, and is easy to machine. When exposed to a fluorine plasma, alumina ceramic becomes fluorinated creating particle contaminants. Yttria (Y2O3) ceramic may be thermal sprayed onto a plasma facing surface of the dielectric window to provide a protective coating that makes the dielectric window more etch resistant. Such a thermal spray coating has a finite thickness and therefore coating lifetime is limited. In addition, yttria coatings may have fluorination problems.

[0016] The dielectric TCP window also plays an outsize role in chamber productivity performance given its location above the wafer and its proximity to the TCP coil terminals. As the TCP RF power increases, the TCP windows are subjected to higher ion energies and plasma densities, which can generate particles from its surface that give rise to on-wafer defects.

[0017] Bulk laminate windows have been introduced and demonstrated improved productivity performance in several applications. These bulk laminate windows can comprise a plasma-facing bulk yttrium aluminum garnet (YAG) layer with a substrate layer of at least one of zirconia-toughened alumina (ZTA) and magnesium aluminum oxide (spinel). Additionally, the YAG layer demonstrates robust resistance to fluorination, leading to very low particle generation. Major drawbacks of the bulk laminate are the machinability of ZTA and high manufacturing cost.

[0018] Machinability and thus affordability, along with the need to move to higher RF powers, are all key drivers for next generation dielectric TCP windows making novel approaches necessary. As RF power continues to increase, to enable the etching of higher-aspect ratio features, thermal management of the chamber environment becomes more challenging due to the increased heat fluxes from the plasma into the chamber components. Thermal management, those that rely on backside air convection and thermal contact to neighboring chamber components, may no longer be sufficient: potentially resulting in a higher risk of cracking the dielectric TCP window due to the temperature gradient variations that cause high thermal stresses in the material. In addition, emerging applications have heightened on-wafer process sensitivity to thermal uniformity of the chamber environment. New solutions are therefore necessary to maintain chamber temperature uniformity. One such solution is a break away from a monolithic architecture to an assembled window.

[0019] Some embodiments provide a dielectric window assembly comprising a plasma facing body with a plasma facing yttrium aluminum oxide surface on a first side, a backing plate, and a bond layer of an adhesive material joining the backing plate to the second side of the plasma facing body. In some embodiments, the backing plate contains channels.

[0020] To facilitate understanding, FIG. 1 is a high-level flow chart of an embodiment of a method of forming and using a dielectric window assembly in a plasma processing chamber. A plasma facing body is formed (step 104). FIG. 2A is a schematic side cross-sectional view of a plasma facing body 200 formed in an embodiment. The plasma facing body 200 comprises a plasma facing surface 201 on a first side of the plasma facing body 200. The plasma facing surface is plasma resistant and comprises yttrium aluminum oxide. In some embodiments, the plasma facing surface 201 comprises a phase of yttrium aluminum oxide, such as yttrium aluminum garnet (YAG). In some embodiments, the plasma facing body 200 further comprises a substrate layer 202. In some embodiments, the substrate layer 202 comprises zirconia toughened alumina (ZTA), where the amount of zirconia in the alumina is tunable. In some embodiments, the plasma facing body 200, is disk shaped with a central aperture 206. The centralaperture 206 forms a gas injector mount that accommodates a gas injector. The gas injector delivers gases into the plasma processing chamber.

[0021] Tn some embodiments, the formation of the plasma facing body 200 is achieved through a process of co-sintering by a methodology known as Spark Plasma Sintering (SPS) to form a laminate structure. In some embodiments, the coefficient of thermal expansion (CTE) of a ceramic material plays an important role. In the two materials of the laminate structure, for a proper co-sintering to occur, SPS methodology often necessitates that the material CTEs be closely matched. In some embodiments, YAG is chosen as the plasma facing surface 201 for its excellent plasma resistance. Correspondingly, ZTA is chosen as the substrate layer 202, as it provides a CTE match to the YAG and good thermomechanical strength. One downside of this materials selection, however, is that it is difficult and time-consuming to machine complex features in ZTA with traditional tooling due to ZTA’s high mechanical strength and toughness. For this reason, it is not practical to form detailed features such as channels in ZTA by subtractive machining. The amount of zirconia in alumina is tunable and thus can control to some extent the toughness of the ZTA material. In some embodiments, the plasma facing surface 201 has a thickness in the range of 200 microns (pi) to 5 millimeters (mm). In some embodiments, the plasma facing surface 201 has a thickness in the range of 500 p to 2 mm.

[0022] In some embodiments, the substrate layer 202 can be comprised of 75 weight% to 99 weight% alumina. The substrate layer 202, may further be tuned by having 1 weight % to 25 weight % zirconia. In some embodiments, the plasma facing surface 201 of the plasma facing body 200 can be at least one of the yttrium aluminum oxide phases. In some embodiments, the plasma facing layer 201 comprises 60 weight % to 100 weight % yttrium aluminum oxide, such as YAG.

[0023] In addition to the formation of the plasma facing body 200 (step 104) shown in FIG. 2A, a backing plate 208 is formed (step 108), as depicted in the cross-sectional view in FIG. 2B. In some embodiments, the backing plate 208 comprises at least one of alumina ceramic, zirconium oxide, yttrium oxide, lanthanum oxide, and aluminum nitride ceramic. In some embodiments, the backing plate 208 is formed from a material with a low dielectric loss [<8x 10^ at 2-60 MHz], (i.e., is a dielectric material) and is also a material with high thermal conductivity [>25 W / m*K (Watts per meter- Kelvin)]. In some embodiments, the backing plate 208 is formed by sintering an alumina powder to form an alumina ceramic disk. In some embodiments, the backing plate 208 contains a bayonet feature 212 formed in the backing plate 208. The bayonet feature 212 allows for holding / locking a gas injector in place. In some embodiments, a mounting notch 216 is also formed in the backing plate 208. The mounting notch 216 may be used to mount the dielectric window assembly in the plasma processing chamber. Since alumina can be more easily machined than ZTA, the formation of the bayonet feature 212 and the mounting notch 216 may be provided by machining the backing plate 208. In some embodiments, the bayonet feature 212 and mounting notch 216 may be formed during the sintering process of the alumina. Since alumina is easily machinable, complex structures may be machined in the backing plate 208. In some embodiments,the backing plate 208 is greater than 99 weight% alumina (aluminum oxide (AI2O3)). In some embodiments, the bulk material of the backing plate 208 is a ceramic material, wherein the ceramic material has a purity of minimum 99 weight% of aluminum oxide.

[0024] Next, the backing plate 208 is bonded to the plasma facing body 200 (step 112). The FIG. 2C is a schematic cross-sectional view of the dielectric window assembly 240 showing the backing plate 208 bonded to a second side, substrate side, of the plasma facing body 200 where the second side of the plasma facing body 200 is opposite the first side of the plasma facing body 200 and the plasma facing surface 201, where the bonding is by a bond layer 244 of an adhesive material. In some embodiments, the bond layer 244 comprises at least one of a polymer and glass. In some embodiments, the bond layer 244 is a polymer that is at least one of silicone, epoxy, polyurethane, acrylic, and polyimidc. In some embodiments, the bond layer 244 can be formed by applying liquid adhesive or pre-formed adhesive film (commonly called B-stage). Post curing of adhesive is typically required to achieve a desired bond strength. In some embodiments, the bond layer 244 further comprises a thermally conductive filler to increase the thermal performance of the bond layer 244. In some embodiments, the filler is a dielectric filler and comprises at least one of graphite, aluminum nitride, boron nitride, and aluminum oxide. The increased thermal conductivity of the bond aided by the filler helps ensure effective heat flow out of the system and thus better uniformity across the dielectric window assembly 240. In some embodiments, the bond layer 244 does not have thermally conductive filler. A sufficiently thin bond layer 244 may not need a thermally conductive filler.

[0025] FIGS. 3A-B, are schematic cross-sectional views of other embodiments. In FIG. 3A, the substrate layer 302 of the plasma facing body 300 of the dielectric window assembly 340 forms a step 305. In addition, temperature control channels 320 are formed on a bottom surface of the backing plate 308. The temperature control channels 320 may be formed by either machining the backing plate 308 or may be formed by the sintering mold in forming the backing plate 308. In some embodiments, the bond layer 344 both bonds the backing plate 308 to the plasma facing body 300 and seals the temperature control channels 320. In such embodiments, the bond layer 344 must be of a material that can fluid seal the temperature control channels 320. In some embodiments, the bond layer 344 is formed from a polymer, such as silicone.

[0026] In FIG. 3B, the substrate layer 302 of the plasma facing body 300 of the dielectric window assembly 340 forms a step 305. In some embodiments, the backing plate is formed by a first plate 308a and a second plate 308b. Temperature control channels 320 are formed on a bottom surface of the first plate 308a. The temperature control channels 320 may be formed by either machining the first plate 308a or may be formed by the sintering mold in forming the first plate 308a. The first plate 308a is joined to the second plate 308b in order to enclose the temperature control channels 320. The first plate 308a may be joined to the second plate 308b by a ceramic diffusion bonding process where the two are fused together by a facilitating agent / compound_forming a solid-state bond. In some embodiments, the firstplate 308a is bonded to the second plate 308b using a high-temperature bonding technique. For example, the first plate 308a is bonded to the second plate 308b using a high-temperature epoxy bonding process. In other examples, a glass fritted bonding process is used. The first plate 308a and the second plate 308b are heated to a bonding temperature (and the glass fritted bonding layer joins the first plate 308a and the second plate 308b). In other examples, diffusion bonding, lamination, or co-firing is used to bond the first plate 308a to the second plate 308b with or without an intervening layer. In some embodiments, ceramic sheets (e.g., green sheets) are patterned, stacked, and co-fired to form the first plate 308a and the second plate 308b with temperature control channels 320. In other words, selected ones of the ceramic sheets are patterned or cut to define different layers. For example, some layers are cut to define slices or layers of the temperature control channel 320 pattern. Other layers are solid and do not need to be cut to form the temperature control channels 320. The layers are stacked and fired. Ceramic paste may be used between the ceramic layers to enhance bonding.

[0027] The bond layer 344 bonds the second plate 308b to the plasma facing body 300. In such embodiments, the bond layer 344 does not need to be of a material that can fluid seal the temperature control channels 320. In some embodiments, the bond layer 344 is formed from a polymer or glass. In some embodiments, the bond layer 344 comprises a polymer comprising at least one of silicone, epoxy, polyurethane, acrylic, and polyimide. The bond layer 344 can be formed by applying liquid adhesive or pre-formed adhesive film (commonly called B-stage). Post curing of adhesive is typically required to achieve a desired bond strength. In some embodiments, the bond layer 344 further comprises a thermally conductive filler to increase the thermal performance of the bond layer 344. In some embodiments, the filler comprises at least one of aluminum nitride, boron nitride, and aluminum oxide. The increased thermal conductivity of the bond aided by the filler helps ensure effective heat flow out of the system and thus better uniformity across the dielectric window.

[0028] In some embodiments, a liquid is flowed through the temperature control channels 320. In some embodiments, the liquid includes a dielectric liquid (e.g., Fluorinert FC-3283 from 3M) or other suitable dielectric liquid (e.g., with reduced impact on the RF magnetic fields passing through the liquid). The pattern of the temperature control channels and / or the number of zones are selected to provide predetermined levels of thermal management for a particular application. In some embodiments, the temperature control channels may be completely embedded in the backing plate.

[0029] A gas injector 352 is shown mounted in the dielectric window assembly 340. A first sealing O-ring 356 is placed between the gas injector 352 and the dielectric window assembly 340, as shown to create a plasma seal between the gas injector 352 and the dielectric window assembly 340. A second sealing O-ring 360 is placed between the dielectric window assembly 340 and a pinnacle or chamber wall. The first sealing O-ring 356 and the second sealing O-ring 360 create seals that prevent plasma from reaching the bond layer 344, protecting the bond layer 344 from plasma degradation. Some embodiments, like the dielectric window assembly 240, shown in FIG. 2C, do not provide a seal betweenthe bond layer 244 and the plasma region. Instead, such embodiments place the bond layer 244 a distance from the active plasma region where plasma must pass through a narrow gap in order to minimize damage to the bond layer 244 from plasma. In addition, gas tight connections between gas sources and the gas injector 352 prevent process gases from reaching the bond layer 344.

[0030] FIG. 4 is a cross-sectional top view of the backing plate 408 with channels 420 that may be used in some embodiments. Inner walls 424 separate the channels. An inlet port 412 and an outlet port 414 allow temperature control fluid to flow into and out of the channels. The temperature profile of the liquid cooled ceramic window is controlled by the liquid coolant such as a dielectric liquid circulating inside the cooling channels. The liquid cooled ceramic window supports a wider range of plasma power levels and temperature requirements for different etch applications.

[0031] In some embodiments, channels may be formed inside of the backing plate. The formation of such interior channels is described in WO / 2022 / 10743, published on May 27, 2022, entitled “Ceramic Component with Channels,” which is incorporated by reference for all purposes.

[0032] The component, such as the dielectric window assembly 240 is mounted as a component of a plasma processing chamber (step 116). To facilitate understanding, FIG. 5 schematically illustrates an example of a plasma processing chamber system 500 that may be used in some embodiments. The plasma processing chamber system 500 includes a plasma reactor 502 having a plasma processing chamber 504 therein. A plasma power supply 506, tuned by a power matching network 508, supplies power to a transformer coupled plasma (TCP) coil 510 located near the dielectric window assembly 240. The TCP coil 510 creates a plasma 514 in the plasma processing chamber 504 by providing an inductively coupled power into the plasma reactor 502 through the dielectric window assembly 240. A pinnacle 572 extends from a chamber wall 576 of the plasma processing chamber 504 to and mates or contacts with the dielectric window assembly 240 forming a pinnacle ring. The pinnacle 572 is angled with respect to the chamber wall 576 and the dielectric window assembly 240. For example, the interior angle between the pinnacle 572 and the chamber wall 576 and the interior angle between the pinnacle 572 and the dielectric window assembly 240 may each be greater than 90° and less than 180°. The pinnacle 572 provides an angled ring near the top of the plasma processing chamber 504, as shown. The TCP coil (upper power source) 510 may be configured to produce a uniform diffusion profile within the plasma processing chamber 504. For example, the TCP coil 510 may be configured to generate a toroidal power distribution in the plasma 514. The dielectric window assembly is provided to separate the TCP coil 510 from the plasma processing chamber 504 while allowing energy to pass from the TCP coil 510 to the plasma processing chamber 504. A wafer bias voltage power supply 516 tuned by a bias matching network 518 provides power to substrate support 564 to set the bias voltage when a process wafer 566 is placed on the substrate support 564. A controller 524 controls the plasma power supply 506 and the wafer bias voltage power supply 516.

[0033] The plasma power supply 506 and the wafer bias voltage power supply 516 may be configured to operate at specific radio frequencies such as for example, 13.56 megahertz (MHz), 27 MHz, 2 MHz, 60 MHz, 400 kilohertz (kHz), 2.54 gigahertz (GHz), or combinations thereof. Plasma power supply 506 and wafer bias voltage power supply 516 may be appropriately sized to supply a range of powers in order to achieve the desired process performance. For example, in one embodiment, the plasma power supply 506 may supply power in a range of 50 to 5000 Watts, and the wafer bias voltage power supply 516 may supply a bias voltage in a range of 20 to 2000 volts (V). In addition, the TCP coil 510 and / or the substrate support 564 may be comprised of two or more sub-coils or sub-electrodes. The sub-coils or sub-electrodes may be powered by a single power supply or powered by multiple power supplies.

[0034] As shown in FIG. 5, the plasma processing chamber system 500 further includes a gas source / gas supply mechanism 530. The gas source 530 is in fluid connection with plasma processing chamber 504 through a gas inlet, such as a gas injector 540. The gas injector 540 has at least one borehole 541 to allow gas to pass through the gas injector 540 into the plasma processing chamber 504. The gas injector 540 may be located in any advantageous location in the plasma processing chamber 504 and may take any form for injecting gas. Preferably, however, the gas inlet may be configured to produce a “tunable” gas injection profile. The tunable gas injection profile allows independent adjustment of the respective flow of the gases to multiple zones in the plasma process chamber 504. More preferably, the gas injector is mounted to the dielectric window assembly 240. The process gases and by-products are removed from the plasma process chamber 504 via a pressure control valve 542 and a pump 544. The pressure control valve 542 and pump 544 also serve to maintain a particular pressure within the plasma processing chamber 504. The pressure control valve 542 can maintain a pressure of less than 1 Torr during processing. An edge ring 560 is placed around the top part of the substrate support 564. A temperature controller 548 provides temperature control fluid to and from the channels in the dielectric window assembly 240 through ports 549. The temperature controller 548 may provide heating fluids to heating channels and cooling fluids to cooling channels in the dielectric window assembly 240. The gas source / gas supply mechanism 530, plasma power supply 506, wafer bias voltage power supply 516, and the temperature controller 548 are controlled by the controller 524. A Kiyo®, Strata®, or Vector® by Lam Research Corp.® of Fremont, CA, may be used to practice an embodiment.

[0035] The processing chamber is used to plasma process a plurality of wafers (step 120). The plasma processing performed by the processing chamber may include one or more processes of etching, depositing, passivating, or another plasma process. The plasma processing may also be performed in combination with non-plasma processing.

[0036] In some embodiments, the dielectric window assembly 240 provides 10,000 RF hours of use.Such an embodiment allows for the use of the dielectric window assembly 240 for about 10,000 RF hours without requiring a changing of the dielectric window assembly 240. Having a part that lasts for 10,000RF hours reduces maintenance costs and downtime. In some embodiments, the dielectric window assembly 240 has a lifetime that is greater than the lifetime of the plasma processing chamber system 500.

[0037] In some embodiments, the dielectric window assembly comprises at least three layers of different materials. In some embodiments, a dielectric window assembly may be exposed to temperatures over a temperature range from -10° C to 200° C. Sintering a unitary piece of three different materials may result in cracked components over such temperature ranges due to CTE mismatch. By providing a bonding layer of epoxy or silicone between at least one layer, cracking is reduced.

[0038] While this disclosure has been described in terms of several preferred embodiments, there arc alterations, permutations, and various substitute equivalents, that fall within the scope of this disclosure.It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present disclosure. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and various substitute equivalents as fall within the true spirit and scope of the present disclosure. As used herein, the phrase “A, B, or C” should be construed to mean a logical (“A OR B OR C”), using a non-exclusive logical “OR,” and should not be construed to mean ‘only one of A or B or C. Each step within a process may be an optional step and is not required. Different embodiments may have one or more steps removed or may provide steps in a different order. In addition, various embodiments may provide different steps simultaneously instead of sequentially.

Claims

CLAIMSWhat is claimed:

1. A dielectric window assembly for use in a plasma processing chamber, comprising: a plasma facing body with a plasma facing surface on a first side of the plasma facing body and a second side opposite the first side; wherein the plasma facing surface comprises yttrium aluminum oxide; a backing plate on the second side of the plasma facing body; and a bond layer comprising an adhesive material bonding the plasma facing body to the backing plate to form the dielectric window assembly.

2. The dielectric window assembly, as recited in claim 1, wherein the bond layer comprises at least one of a polymer and glass.

3. The dielectric window assembly, as recited in claim 1, wherein the backing plate comprises alumina.

4. The dielectric window assembly, as recited in claim 1, wherein the bond layer comprises a polymer comprising at least one of silicone, epoxy, polyurethane, acrylic, and polyimide.

5. The dielectric window assembly, as recited in claim 4, wherein the bond layer further comprises a thermally conductive filler.

6. The dielectric window assembly, as recited in claim 5, wherein the thermally conductive filler is dielectric and comprises at least one of graphite, aluminum nitride, boron nitride, and aluminum oxide.

7. The dielectric window assembly, as recited in claim 1, wherein the bond layer is not exposed to plasma.

8. The dielectric window assembly, as recited in claim 7. wherein the bond layer is not exposed to the process gas.

9. The dielectric window assembly, as recited in claim 1, wherein the backing plate has at least one temperature control channel.

10. The dielectric window assembly, as recited in claim 9, wherein the plasma facing body is bonded to a surface of the backing plate to enclose the at least one temperature control channel.

11. The dielectric window assembly, as recited in claim 9, wherein the backing plate comprises: a first plate with a first surface with at least one temperature control channel; and a second plate bonded to the first surface of the first plate to enclose the at least one temperature control channel.

12. The dielectric window assembly, as recited in claim 11, wherein the first plate and the second plate arc at least one of diffusion bonded, glass fritted bonded, and epoxy bonded together.

13. The dielectric window assembly, as recited in claim 9, further comprising a set of ports in fluid connection with the at least one temperature control channel.

14. The dielectric window assembly, as recited in claim 1, the plasma facing body further comprises as a second material at least one of zirconia toughened alumina and spinel (magnesium aluminum oxide), wherein the second material is not plasma facing.

15. The dielectric window assembly, as recited in claim 14, wherein the second material and yttrium aluminum oxide are co- sintered together to form the plasma facing body.

16. The dielectric window assembly, as recited in claim 1, wherein the backing plate forms a gas injector mount for supporting a gas injector.

17. The dielectric window assembly, as recited in claim 1 assembly, wherein the backing plate has at least one surface that has been shaped by machining.

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