Title: Sealed compression washer for joining ceramic plate and metal base plate of electrostatic chuck

Abstract

An electrostatic chuck for a substrate processing system includes a base plate, a ceramic plate, and a bonding layer. The base plate includes a metallic material and a sidewall and an upper and lower surface of the base plate that define a plenum. The base plate further includes an inlet in fluid communication with the plenum and a first plurality of through holes extending from the upper surface to the plenum. The ceramic plate includes a second plurality of through holes extending between its upper and lower surfaces. The bonding layer bonds the base plate and the ceramic plate. The bonding layer includes a plurality of washers. Each washer includes a core including a third material and a coating of a fourth material surrounding the core. The washers and the bonding layer have the same height. An inner diameter of the washers matches a diameter of the first and second plurality of through holes.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Application No. 63 / 317,822, filed March 8, 2022. The entire disclosure of the above application is incorporated herein by reference.

[0002] The present disclosure relates generally to substrate processing systems and, more particularly, to a sealed compression washer for joining a ceramic plate and a metallic base plate of an electrostatic chuck. [Background technology]

[0003] The Background Art provided herein is provided to generally present the contents of the present disclosure. The inventions of the presently named inventors are not admitted expressly or impliedly as prior art to the present disclosure to the extent that they are described in this Background Art section or in aspects of the description that are not prior art at the time of filing.

[0004] Substrate processing systems include processing chambers for performing deposition, etching, and other processing of substrates, such as semiconductor wafers. Examples of processes that can be performed on a substrate include plasma-enhanced chemical vapor deposition (PECVD), chemically enhanced plasma vapor deposition (CEPVD), sputtering physical vapor deposition (PVD), atomic layer deposition (ALD), and plasma-enhanced ALD (PEALD). Further examples of processes that can be performed on a substrate include etching processes (e.g., chemical etching, plasma etching, reactive ion etching, etc.) and cleaning processes.

[0005] During processing, the substrate is placed on a substrate support assembly, such as a pedestal or electrostatic chuck (ESC), which is disposed in a processing chamber of a substrate processing system. A robot typically transports the substrates from one processing chamber to another in the order in which the substrates are processed. During deposition, a gas mixture containing one or more precursors is introduced into the processing chamber and a plasma is generated to activate a chemical reaction. During etching, a gas mixture containing an etching gas is introduced into the processing chamber and a plasma is generated to activate a chemical reaction. The processing chamber is periodically cleaned by supplying a cleaning gas to the processing chamber and generating a plasma. Summary of the Invention

[0006] An electrostatic chuck for a substrate processing system includes a base plate, a ceramic plate, and a bonding layer. The base plate of the electrostatic chuck includes a metallic material, a sidewall defining a plenum, and an upper surface and a lower surface. The base plate further includes an inlet in fluid communication with the plenum and a first plurality of through holes extending from the upper surface to the plenum. The ceramic plate of the electrostatic chuck includes a second plurality of through holes extending between its upper surface and lower surface. The bonding layer bonds the base plate and the ceramic plate. The bonding layer includes a plurality of washers. Each washer includes a core including a third material and a coating of a fourth material surrounding the core. The washers and the bonding layer have the same height. An inner diameter of the washers matches a diameter of the first and second plurality of through holes.

[0007] In a further feature, the core and coating are annular and coaxial.

[0008] In further features, the inlet, the plenum, the inner diameter of the washer, and the first and second pluralities of through-holes are in fluid communication with one another.

[0009] In a further feature, the tie layer comprises a third material.

[0010] In a further feature, the third material comprises a silicone, a urethane, or a flexible epoxy.

[0011] In a further feature, the fourth material comprises polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA).

[0012] In a further feature, the coating includes a first layer of a fourth material disposed on an inner diameter of the core and a second layer of a fourth material disposed on an outer diameter of the core.

[0013] In a further feature, the sum of the thicknesses of the first and second layers is less than or equal to the thickness of the core.

[0014] In a further feature, the sum of the thicknesses of the first and second layers is greater than or equal to the thickness of the core.

[0015] In a further feature, the thickness of the first layer and the thickness of the second layer are different.

[0016] In a further feature, the washer has a diameter of 2 to 20 mm.

[0017] In a further feature, the washer has a thickness of 2 to 10 mils (0.0508 to 0.254 millimeters).

[0018] In a further feature, the core comprises 30-90% of the thickness of the washer and the coating comprises 70-10% of the thickness of the washer.

[0019] In a further feature, the electrostatic chuck further comprises an O-ring disposed about the bonding layer, the O-ring including a second core including a third material and a second coating including a fourth material surrounding the second core.

[0020] In a further feature, the inside diameter of the O-ring is 300 mm and the cross-sectional diameter of the O-ring is 100 to 150 mils (2.54 to 3.81 millimeters).

[0021] In a further feature, the ceramic plate comprises one or more passages, one of the passages connecting one of the second plurality of through holes in the lower surface of the ceramic plate to at least two of the second plurality of through holes in the upper surface of the ceramic plate.

[0022] In still other features, an electrostatic chuck for a substrate processing system includes a base plate, a ceramic plate, and a bonding layer. The base plate includes a sidewall and an upper and lower surface defining a plenum, an inlet in fluid communication with the plenum, and a first plurality of through holes extending from the upper surface to the plenum. The ceramic plate includes a second plurality of through holes extending through the ceramic plate. The bonding layer bonds the base plate and the ceramic plate. The bonding layer includes a plurality of washers. Each washer includes a core and a coating disposed on the core. An inner diameter of the washer matches a diameter of the first and second plurality of through holes.

[0023] In a further feature, the core and coating are annular and coaxial.

[0024] In further features, the base plate comprises a metallic material, the tie layer and the core comprise a third material, and the coating comprises a polymeric material.

[0025] In further features, the base plate comprises a metallic material, the bonding layer comprises a silicone, the core comprises a silicone, a urethane, or a flexible epoxy, and the coating comprises polytetrafluoroethylene (PTFE) or a perfluoroalkoxyalkane (PFA).

[0026] In a further feature, the washer and the bonding layer have the same height.

[0027] In a further feature, the coating partially surrounds the core.

[0028] In a further feature, the coating completely surrounds the core.

[0029] In further features, the inlet, the plenum, the inner diameter of the washer, and the first and second pluralities of through-holes are in fluid communication with one another.

[0030] In a further feature, the coating includes a first layer disposed on an inner diameter of the core and a second layer disposed on an outer diameter of the core.

[0031] In a further feature, the sum of the thicknesses of the first and second layers is less than or equal to the thickness of the core.

[0032] In a further feature, the sum of the thicknesses of the first and second layers is greater than or equal to the thickness of the core.

[0033] In a further feature, the thickness of the first layer and the thickness of the second layer are different.

[0034] In a further feature, the washer has a diameter of 2 to 20 mm.

[0035] In a further feature, the washer has a thickness of between 2 and 10 mils.

[0036] In a further feature, the core comprises 30-90% of the thickness of the washer and the coating comprises 70-10% of the thickness of the washer.

[0037] In a further feature, the electrostatic chuck further comprises an O-ring disposed about the bonding layer, the O-ring comprising a second core comprising the same material as the core of the washer and a second coating surrounding the second core and comprising the same material as the coating of the washer.

[0038] In a further feature, the inside diameter of the O-ring is 300 mm and the cross-sectional diameter of the O-ring is 100 to 150 mils.

[0039] In a further feature, the ceramic plate comprises one or more passages, one of the passages connecting one of the second plurality of through holes in the lower surface of the ceramic plate to at least two of the second plurality of through holes in the upper surface of the ceramic plate.

[0040] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0041] The present disclosure will become better understood from the detailed description and the accompanying drawings.

[0042] [Figure 1A] 1 illustrates an exemplary substrate processing system including an electrostatic chuck (ESC). [Figure 1B] 1 illustrates an exemplary substrate processing system including an electrostatic chuck (ESC).

[0043] [Diagram 2] FIG. 13 is a simplified cross-sectional view of the components of an ESC with a washer in a bonding layer used to bond the base plate and ceramic plate of the ESC according to the present disclosure.

[0044] [Diagram 3] FIG. 2 is a cross-sectional view of a washer prior to curing of the bonding layer.

[0045] [Figure 4] 4 is a plan view of a base plate with a through hole and the washer of FIG. 3 before curing of the bonding layer, the washer being disposed around the through hole on the base plate.

[0046] [Diagram 5] FIG. 2 is a cross-sectional view of an ESC after the bonding layer including the washer has been hardened and the base plate and ceramic plate of the ESC are bonded by the hardened bonding layer.

[0047] [Figure 6] 4 is a cross-sectional view of the washer after the bonding layer has cured.

[0048] [Figure 7] A top view of the through hole and the washer around the through hole in the base plate after the bonding layer has hardened.

[0049] [Figure 8] FIG. 6 is a cross-sectional view of the ESC of FIG. 5 further including an O-ring disposed about the cured bonding layer.

[0050] [Figure 9] FIG. 2 illustrates a cross-sectional view of an exemplary ESC with a ceramic plate that includes a plenum instead of orthogonal through-holes. [Figure 10] FIG. 2 illustrates a cross-sectional view of an exemplary ESC with a ceramic plate that includes a plenum instead of orthogonal through-holes.

[0051] In the drawings, reference numbers may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] An electrostatic chuck (ESC) comprises a ceramic plate bonded to a metal base plate using a bonding layer. Prior to bonding the ceramic plate to the base plate, a number of holes are drilled into the base plate and the ceramic plate. The holes are used to supply gas (e.g., helium) to control the temperature of the substrate during processing. During manufacture, the bonding layer is formed by placing liquid silicone on the base plate and curing the liquid silicone while compressing the ceramic plate and the base plate. To prevent the liquid silicone from blocking the holes in the base plate and the ceramic plate, silicone washers are placed around the holes. Upon curing, the bonding layer including the silicone washers bonds the ceramic plate to the base plate.

[0053] While silicone washers prevent liquid silicone from blocking the pores, they tend to degrade and fail over time after repeated substrate processing and chamber cleaning. Silicone washers fail due to exposure to high processing temperatures, temperature cycles, and reactive plasma species used in substrate processing and chamber cleaning. Specifically, degradants and uncured plasticizers from the silicone washer leak into the pores and block them. In addition, uncured plasticizers from the surrounding bonding material diffuse through the silicone washer and leak into the pores, further blocking them. The pores also become clogged for a variety of other reasons. For example, low gas flow during waferless automated cleaning (WAC) can result in arcing, light emission (i.e., plasma formation), and ultimately bond erosion and degradation of the bonding layer. Clogged pores not only cut off gas flow through the pores, but also compromise the bond between the ceramic plate and the base plate. The degraded bond ultimately causes the ESC to fail.

[0054] The present disclosure provides a washer including an elastic material used as a core material coated with a polymer coating. The elastic core material has mechanical properties to withstand the compressive forces between the base plate and the ceramic plate during the manufacture of the ESC. The core material also has thermodynamic properties to withstand high processing temperatures. Additionally, the polymer coating does not corrode at high processing temperatures, temperature cycling, and exposure to reactive plasma species. The polymer coating acts as a diffusion barrier to the plasma or other reactive species, and also acts as a diffusion barrier to the plasticizers and / or uncured materials of the core. As a result, not only do the pores remain unblocked, but the bond between the ceramic plate and the base plate remains intact after thousands of hours of use of the ESC. These and other features of the present disclosure are described in more detail below.

[0055] The present disclosure is organized as follows. First, with reference to Figures 1A and 1B, an example of a substrate processing system in which an ESC manufactured according to the present disclosure may be used is shown and described. With reference to Figures 2-4, a method of manufacturing an ESC using a covering washer and structural details of the covering washer are shown and described. With reference to Figures 5-8, an ESC manufactured using a covering washer is shown and described. Figures 2-4 show elements of an ESC before curing the bonding layer. Figures 5-8 show elements of an ESC after the bonding layer has cured. Figures 9 and 10 show an example of a ceramic plate with plenums instead of orthogonal through holes.

[0056] FIG. 1A illustrates an example of a substrate processing system 10 that uses inductively coupled plasma to etch substrates such as semiconductor wafers according to the present disclosure. The substrate processing system 10 includes a coil driver circuit 11. In some examples, the coil driver circuit 11 includes an RF source 12, a pulse circuit 14, and a tuning circuit (i.e., matching circuit) 13. The pulse circuit 14 controls a transformer coupled plasma (TCP) envelope of the RF signal generated by the RF source 12 and varies the duty cycle of the TCP envelope during operation between 1-99%. The pulse circuit 14 and the RF source 12 can be integrated or separate.

[0057] The tuning circuit 13 may be directly connected to the induction coil 16. Although the substrate processing system 10 uses a single coil, some substrate processing systems may use multiple coils (e.g., an inner coil and an outer coil). The tuning circuit 13 tunes the output of the RF source 12 to a desired frequency and / or a desired phase and matches the impedance of the induction coil 16.

[0058] The dielectric window 24 is disposed along an upper side of the processing chamber 28. The processing chamber 28 includes a substrate support (or pedestal) 30 for supporting a substrate 34. The substrate support 30 can be fabricated in accordance with the present disclosure, as shown and described in further detail below with reference to FIGS. 2-8. Briefly, the substrate support 30 can include an electrostatic chuck (ESC), or a mechanical chuck, or other types of chucks. The substrate support 30 includes a base plate 32. The base plate 32 includes a metallic material (e.g., aluminum or alloy). A ceramic plate 33 is disposed on an upper surface of the base plate 32. A thermally resistant layer (also referred to as a bonding layer) 36 is disposed between the ceramic plate 33 and the base plate 32 to bond the ceramic plate 33 to the base plate 32, as described in further detail below with reference to FIGS. 2-8. The substrate 34 is disposed on the ceramic plate 33 during processing.

[0059] A heater array 35 including multiple heaters is disposed on the ceramic plate 33 for heating the substrate 34 during processing. For example, the heater array 35 may include printed resistive wires embedded in the ceramic plate 33. One or more additional heaters (not shown), referred to as zone heaters or primary heaters, may be disposed above or below the heater array 35. Also, although not shown, one or more temperature sensors may be disposed on the ceramic plate 33.

[0060] The base plate 32 further comprises a cooling system for cooling the substrate support 30 and controlling the temperature of the substrate 34. The cooling system cools the substrate support 30 using a fluid (e.g., a gas such as helium) provided by a fluid delivery system 39. For example, the cooling system comprises cooling channels 38 disposed in the base plate 32 through which fluid from the fluid delivery system 39 flows to cool the substrate support 30.

[0061] Process gases are supplied to the processing chamber 28 and a plasma 40 is generated in the processing chamber 28. The plasma 40 etches the exposed surface of the substrate 34. An RF source 50, a pulse circuit 51, and a bias matching circuit 52 may be used to apply a bias to the substrate support 30 and control the ion energy during processing.

[0062] A gas delivery system 56 provides a process gas mixture to the processing chamber 28. The gas delivery system 56 may include a process gas and an inert gas source 57, a gas metering system 58, such as valves and mass flow controllers, and a manifold 59. A gas injector 63 may be disposed in the center of the dielectric window 24 and is used to inject the gas mixture from the gas delivery system 56 into the processing chamber 28. Additionally or alternatively, the gas mixture may be injected from a side of the processing chamber 28.

[0063] A temperature controller 64 may be connected to the heater array 35, the zone heaters, and the temperature sensors of the ceramic plate 33. The temperature controller 64 may be used to control the heater array 35 and the zone heaters to control the temperature of the substrate support 30 and the substrate 34. The temperature controller 64 may be in communication with a fluid delivery system 39 to control fluid flow through a cooling system 38 to cool the substrate support 30.

[0064] An exhaust system 65 includes valves 66 and pumps 67 for controlling the pressure in the process chamber 28 and / or for removing reactants from the process chamber 28 by purging or evacuation. A controller 70 may be used to control the etching process. The controller 70 controls the components of the substrate processing system 10. The controller 70 monitors system parameters and controls the delivery of gas mixtures, plasma generation, maintenance, and extinguishing, reactant removal, cooling fluid supply, etc. The controller 70 may also control various aspects of the coil driver 11, the RF source 50, and the bias matching circuit 52.

[0065] 1B illustrates another exemplary substrate processing system 100 including a processing chamber 102 configured to generate a capacitively coupled plasma. Although this example is described for plasma-enhanced chemical vapor deposition (PECVD), the teachings of the present disclosure may be applied to other types of substrate processing, such as atomic layer deposition (ALD), plasma-enhanced ALD (PEALD), CVD, or other processes including etching and cleaning.

[0066] The substrate processing system 100 comprises a process chamber 102 that encloses other components of the substrate processing system 100 and contains the RF plasma (if used). The process chamber 102 comprises an upper electrode 104 and an electrostatic chuck (ESC) 106 or other type of substrate support. During operation, a substrate 108 is positioned on the ESC 106.

[0067] For example, the upper electrode 104 may include a gas distribution apparatus 110, such as a showerhead, for introducing and distributing process gases into the processing chamber 102. The showerhead 110 may include a stem portion with one end connected to an upper surface of the processing chamber 102. A base portion of the showerhead 110 is generally cylindrical and extends radially outward from the other end of the stem portion away from the upper surface of the processing chamber 102. A substrate-facing surface or faceplate of the base of the showerhead 110 includes a number of outlets or mechanisms (e.g., slots or through-holes) through which vaporized precursors, process gases, cleaning gases, or purge gases can flow into the processing chamber 102.

[0068] The ESC 106 may be fabricated in accordance with the present disclosure, as shown and described in further detail below with reference to FIGS. 2-8. Briefly, the ESC 106 includes a base plate 112 that functions as a bottom electrode. The base plate 112 includes a metallic material (e.g., aluminum or alloy). A ceramic plate 114 is disposed on an upper surface of the base plate 112. A thermal resistance layer (also called a bonding layer) 116 is disposed between the ceramic plate 114 and the base plate 112 for bonding the ceramic plate 114 to the base plate 112, as described in further detail below with reference to FIGS. 2-8. The ceramic plate 114 includes a heater array 152 in accordance with the present disclosure for heating the substrate 108. The heater array 152 includes printed resistive wires embedded in the ceramic plate 114. One or more additional heaters (not shown), referred to as zone heaters or primary heaters, may be disposed above or below the heater array 152. Also, not shown, one or more temperature sensors may be disposed on the ceramic plate 114.

[0069] The base plate 112 further includes a cooling system for cooling the ESCs 106 and controlling the temperature of the substrate 108. The cooling system uses a fluid (e.g., a gas such as helium) provided by a fluid delivery system 154 to cool the ESCs 106 and control the temperature of the substrate 108. For example, the cooling system includes cooling channels 118 through which fluid from the fluid delivery system 154 is channeled to cool the ESCs 106 and control the temperature of the substrate 108.

[0070] When a plasma is used, an RF generating system (or RF source) 120 generates and outputs an RF voltage to one of the upper electrode 104 and the lower electrode (e.g., the base plate 112 of the ESC 106). The other of the upper electrode 104 and the base plate 112 may be DC grounded, AC grounded, or floating. For example, the RF generating system 120 may include an RF generator 122 that generates RF power that is delivered to the upper electrode 104 or the base plate 112 by a matched distribution network 124. In other examples, not shown, a plasma may be inductively or remotely generated and delivered to the process chamber 102.

[0071] Gas delivery system 130 includes one or more gas sources 132-1, 132-2, ..., and 132-N (collectively, gas sources 132), where N is an integer greater than zero. Gas sources 132 are connected to manifold 140 by valves 134-1, 134-2, ..., and 134-N (collectively, valves 134) and mass flow controllers 136-1, 136-2, ..., and 136-N (collectively, mass flow controllers 136). Vapor delivery system 142 supplies vaporized precursors to manifold 140, or to another manifold (not shown) connected to process chamber 102. An output of manifold 140 is provided to process chamber 102. Gas sources 132 may supply process gases, cleaning gases, or purge gases.

[0072] A temperature controller 150 may be connected to the heater array 152, the zone heaters, and the temperature sensors of the ceramic plate 114. The temperature controller 150 may be used to control the heater array 152 and the zone heaters to control the temperature of the ESC 106 and the substrate 108. The temperature controller 150 may be in communication with a fluid delivery system 154 to control fluid flow through the cooling system 118 to cool the ESC 106. Valves 156 and pumps 158 may be used to evacuate reactants from the processing chamber 102. A system controller 160 controls the components of the substrate processing system 100.

[0073] 2 shows a simplified cross-sectional view of components of an ESC 200 according to the present disclosure. The components of the ESC 200 are shown separated from one another to illustrate the assembly and manufacturing methods described below. Furthermore, only the components relevant to the present disclosure are shown in a highly simplified manner.

[0074] For example, ESC 200 includes a base plate 202 and a ceramic plate 204. ESC 200 is similar to ESCs 30 and 106 described above with reference to Figures 1A and 1B and may be used in substrate processing systems 10 and 100 described above with reference to Figures 1A and 1B. After ESC 200 is fabricated as described below, a substrate 206 can be placed on ceramic plate 204 and processed as described above with reference to Figures 1A and 1B.

[0075] The base plate 202 comprises a gas inlet 210 through which a gas (e.g., helium) is supplied. The base plate 202 comprises a plenum 212 defined by its top surface 214, bottom surface 216, and sidewalls 218. The plenum 212 is shown in a highly simplified manner. The base plate 202 may instead comprise fluid flow passages similar to the cooling channels 38 and 118 shown with reference to Figures 1A and 1B and described above. Hereinafter, the fluid flow passages will be referred to as the plenum 212. The gas inlet 210 is in fluid communication with the plenum 212.

[0076] The base plate 202 includes a plurality of through-holes 220-1, 220-2, 220-3, and 220-4 (collectively, through-holes 220). Although only four through-holes 220 are shown for purposes of illustration, the base plate 202 may include a plurality of through-holes 220. The through-holes 220 may be arranged in a pattern (e.g., a zone). An example pattern is shown in FIG. 4. The through-holes 220 extend from the top surface 214 of the base plate 202 to the plenum 212. The through-holes 220, the plenum 212, and the gas inlet 210 are in fluid communication with each other.

[0077] The ceramic plate 204 also includes a plurality of through holes 222-1, 222-2, 222-3, and 222-4 (collectively, through holes 222). Again, while only four through holes 220 are shown for purposes of illustration, the ceramic plate 204 may include a plurality of through holes 220. The through holes 222 extend from a top surface 224 of the ceramic plate 204 to a bottom surface 226 of the ceramic plate 204. The through holes 222 are arranged in the same pattern as the through holes 220. Thus, the through holes 222 coincide with the through holes 220 when the ceramic plate 204 is bonded to the base plate 202 as described below (see FIG. 5).

[0078] During manufacture of the ESC 200, the ceramic plate 204 is bonded to the base plate 202 by forming a bonding layer between the ceramic plate 204 and the base plate 202 (see FIG. 5). The bonding layer is formed as follows. Prior to forming the bonding layer, a plurality of washers 230-1, 230-2, 230-3, and 230-4 (collectively, washers 230) are disposed around the through holes 220 on the top surface 214 of the base plate 202. A top view of the washers 230 disposed on the top surface 214 of the base plate 202 is shown and described in further detail with reference to FIG. 4. The washer 230 includes a core 232 encapsulated in a coating 234. The washers 230 are described in further detail with reference to FIG. 3.

[0079] After placing the washer 230 on the base plate 202, a layer 240 of uncured liquid silicone is placed on the top surface 214 of the base plate 202. The washer 230 is taller than the thickness (i.e., height) of the uncured liquid silicone layer 240. Thus, the washer 230 prevents the uncured liquid silicone from flowing into the through-holes 220 during the fabrication of the ESC 200. After placing the uncured liquid silicone layer 240, the ceramic plate 204 and the base plate 202 are compressed together at the same time that the uncured liquid silicone layer 240 is cured. When the uncured liquid silicone layer 240 is cured, a bonding layer is formed between the ceramic plate 204 and the base plate 202 (see FIG. 5). The bonding layer bonds the ceramic plate 204 and the base plate 202.

[0080] During bonding layer formation (i.e., during curing and compression), the washer 230 shrinks. After curing and compression, the inner diameter of the washer 230 matches the diameter of the through-holes 220 and 222 (see FIG. 5). Thus, after bonding layer formation (i.e., after the ESC 200 is fabricated as described above), the gas inlet 210, the plenum 212, and the through-holes 220 and 222 are in fluid communication with each other (see FIG. 5). In use, the substrate 206 may be placed on the ceramic plate 204 during processing. Gas supplied through the inlet 210 flows through the plenum 212 and the through-holes 220 and 222 and is used to control the temperature of the substrate 206 during processing.

[0081] 3 shows a more detailed cross-sectional view of washer 230 prior to the formation of the bonding layer (i.e., prior to curing and compression). Washer 230 is annular. Washer 230 includes core 232 and coating 234 disposed about core 232. Core 232 is annular. Core 232 is encapsulated (i.e., coated) with coating 234. Coating 234 is disposed about the inner and outer diameters of core 232. Core 232 may be fully or partially coated with coating 234. For example, coating 234 may be patterned on the inner and outer diameters of core 232 when washer 230 is manufactured.

[0082] The coating 234 includes a first (inner) layer 234-1 disposed on an inner diameter (ID) of the core 232 and a second (outer) layer 234-2 disposed on an outer diameter (OD) of the core 232. The first layer 234-1 and the second layer 234-2 are annular. The core 232 and the first layer 234-1 and the second layer 234-2 are coaxial. The OD of the first layer 234-1 matches the ID of the core 232. The ID of the second layer 234-2 matches the OD of the core 232. The ID of the first layer 234-1 is the ID of the washer 230. The OD of the second layer 234-2 is the OD of the washer 230. The ID of washer 230 (i.e., the ID of first layer 234-1) is larger than the diameter of through hole 220 before the bonding layer is cured (see FIG. 4). The ID of washer 230 (i.e., the ID of first layer 234-1) is approximately equal to and aligns with the diameter of through hole 220 after the bonding layer is cured (see FIG. 5).

[0083] The thickness of washer 230 is the sum of the thickness of core 232 and the thickness of coating 234. The thickness of coating 234 is the sum of the thicknesses of first layer 234-1 and second layer 234-2. The thickness of washer 230 is the distance between the ID and OD of washer 230. That is, the thickness of washer 230 is the distance between the ID of first layer 234-1 and the OD of second layer 234-2.

[0084] Core 232 constitutes 30-90% of the thickness of washer 230. Coating 234 (i.e., the combination of first layer 234-1 and second layer 234-2) constitutes 70-10% of the thickness of washer 230. For example, when the thickness of core 232 is 40% of the thickness of washer 230, the thickness of coating 234 is 60% of the thickness of washer 230. When the thickness of core 232 is 50% of the thickness of washer 230, the thickness of coating 234 is 50% of the thickness of washer 230. When the thickness of core 232 is 60% of the thickness of washer 230, the thickness of coating 234 is 40% of the thickness of washer 230.

[0085] In some examples, the thickness of the coating 234 (i.e., the sum of the thicknesses of the first layer 234-1 and the second layer 234-2) is less than or equal to the thickness of the core 232. In some examples, the thickness of the first layer 234-1 and the thickness of the second layer 234-2 may be different, and the sum of the thicknesses of the first layer 234-1 and the second layer 234-2 may be less than or equal to the thickness of the core 232. Conversely, in other examples, the thickness of the coating 234 (i.e., the sum of the thicknesses of the first layer 234-1 and the second layer 234-2) is greater than or equal to the thickness of the core 232. In some examples, the thickness of the first layer 234-1 and the thickness of the second layer 234-2 may be different, and the sum of the thicknesses of the first layer 234-1 and the second layer 234-2 is greater than or equal to the thickness of the core 232. The core 232 and the first and second layers 234-1, 234-2 having the particular thicknesses described above can be manufactured using multiple layer lamination or other manufacturing processes. Example dimensions for the washer 230 are provided below after the description of FIG.

[0086] The core 232 includes a cured elastic material (e.g., silicone, urethane, or flexible epoxy). The core 232 provides a stable reaction force between the ceramic plate 204 and the base plate 202 during use of the ESC 200. The coating 234 includes a polymer material. For example, the polymer material includes polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA). The polymer material has high melt strength, stability at high processing temperatures, excellent crack and stress resistance, and a low coefficient of friction. As a result, the polymer material can withstand harsh environments such as electrical, chemical, and thermal harshness, as well as mechanical stress, such as those experienced by the ESC 200 in a processing chamber. The coating 234 provides a high-quality permanent chemical seal during use of the ESC 200 and prevents the through-holes 220 and 222 from clogging.

[0087] Specifically, the core 232 has mechanical properties to withstand the compressive forces between the base plate 202 and the ceramic plate 204 during manufacture and use of the ESC 200. Additionally, the core 232 has thermomechanical properties to withstand the bond layer curing and high processing temperatures to which the ESC 200 is subjected during use in a processing chamber.

[0088] Additionally, coating 234 does not corrode due to exposure to high processing temperatures, temperature cycles, and reactive plasma species encountered during use of ESC 200 in a processing chamber. Coating 234 acts as a diffusion barrier to plasma or other reactive species used in the processing chamber. Coating 234 also acts as a diffusion barrier to plasticizers and / or uncured materials in core 232 that may otherwise clog through-holes 220 and 222. As a result, not only do through-holes 220 and 222 remain unclogging, but the bond between ceramic plate 204 and base plate 202 remains intact after thousands of hours of use of ESC 200 in a processing chamber.

[0089] More specifically, coating 234 prevents degradation products and uncured plasticizers from washer 230 from leaking into through-holes 220 and 222 and clogging holes 220 and 222. Also, uncured plasticizers from the surrounding bonding material in the bonding layer do not diffuse through washer 230 and leak into through-holes 220 and 222, thus preventing clogging of through-holes 220 and 222. Additionally, coating 234 also prevents clogging of through-holes 220 and 222 due to low gas flow during waferless automatic cleaning (WAC). Low gas flow during WAC can result in arcing, light emission, and ultimately bond erosion and degradation of the bonding layer, which can cause clogging of through-holes 220 and 222 without coating 234. Preventing clogging of through-holes 220 and 222 allows unimpeded gas flow through through-holes 220 and 222, which is used to regulate the temperature of substrate 206 during processing. Additionally, by using the washer 230, the bond between the ceramic plate 204 and the base plate 202 remains intact, preventing failure of the ESC 200.

[0090] FIG. 4 shows a plan view of the through-holes 220 and washers 230 disposed around the through-holes 220 during the fabrication of the ESC 200 before the bonding layer is cured. For example, the through-holes 220 may be disposed on the top surface 214 of the base plate 202 in the pattern as shown. Alternatively, the through-holes 220 may be disposed in any other pattern suitable for controlling the temperature of the substrate 206 with the gas supplied through the inlet 210. For example, the pattern may include concentric zones, quadrants (e.g., pie-shaped zones), or any other pattern. The pattern in which the through-holes 220 are disposed can be selected depending on the process requirements. The through-holes 222 in the ceramic plate 204 are disposed in the same pattern as the through-holes 220. Accordingly, the washers 230 are disposed in the same pattern as the through-holes 220 and 222.

[0091] FIG. 5 shows a cross-sectional view of ESC 200 manufactured as described above with reference to FIGS. 2-4 (i.e., after curing and compression). In ESC 200, when bonding layer 240 shown in FIG. 1 is cured and ceramic plate 204 and base plate 202 are compressed as described above, bonding layer 242 is formed between ceramic plate 204 and base plate 202. Bonding layer 242 bonds ceramic plate 204 and base plate 202. As shown in more detail in FIGS. 6 and 7, the ID of washer 230 in bonding layer 242 matches through holes 220 and 222 after layer 240 is cured and ceramic plate 204 and base plate 202 are compressed. Specifically, the ID of first layer 234-1 of washer 230 matches the diameter of through holes 220 and 222 after layer 240 is cured and ceramic plate 204 and base plate 202 are compressed. Washer 230 prevents through-holes 220 and 222 from clogging as described above.

[0092] 6 shows a more detailed cross-section of washer 230 after formation of bonding layer 242 (i.e., after curing and compression). Once bonding layer 242 is formed after the curing and compression process is performed as described above, the ID of washer 230 matches the diameter of through-hole 220. Specifically, the ID of first layer 234-1 of washer 230 aligns with the diameter of through-hole 220. The ID of first layer 234-1 of washer 230 also matches the diameter of the corresponding through-hole 222 in ceramic plate 204, as shown in FIGS. 5 and 8.

[0093] 7 shows a top view of through hole 220 and surrounding washer 230 in base plate 202 after formation of bonding layer 242 (i.e., after curing and compression). Again, when bonding layer 242 is formed after the curing and compression process is performed as described above, the ID of washer 230 in bonding layer 242 matches the diameter of through hole 220. Specifically, the ID of first layer 234-1 of washer 230 aligns with the diameter of through hole 220. The ID of first layer 234-1 of washer 230 also matches the diameter of through hole 222 in ceramic plate 204 shown in FIGS. 5 and 8.

[0094] FIG. 8 illustrates a cross-sectional view of ESC 200, manufactured as described above with reference to FIGS. 2-4, with the addition of O-ring 250 disposed about bonding layer 242. O-ring 250 protects the outer edge of bonding layer 242. Specifically, O-ring 250 prevents process gases and other reactive species from reacting with bonding layer 242. O-ring 250 includes core 252 and coating 254. Core 252 of O-ring 250 includes a material similar to core 232 of washer 230. As such, core 252 of O-ring 250 will not be described in detail again for the sake of brevity. Coating 254 of O-ring 250 includes a material similar to coating 234 of washer 230. As such, coating 254 of O-ring 250 will not be described in detail again for the sake of brevity.

[0095] O-ring 250 is structurally and functionally different from washer 230 in many respects. Specifically, O-ring 250 has significantly different dimensions and serves a different function than washer 230. For example, O-ring 250 is structurally different from washer 230 in that O-ring 250 has a circumference (ID) of approximately 300 mm (roughly the diameter of ESC 200), while washer 230 has a circumference (i.e., OD of second layer 234-2) of approximately 2-20 mm. Additionally, O-ring 250 has a cross-sectional diameter (i.e., thickness) of approximately 100-150 mils, while washer 230 has a cross-sectional diameter of approximately 2-10 mils.

[0096] Functionally, O-ring 250 protects the outer edge of bonding layer 240, while washer 230 prevents through-holes 220 and 220 from clogging. Also, unlike washer 230, O-ring 250 is not subjected to the curing and bonding processes used to bond ceramic plate 204 and base plate 202, and therefore does not need to withstand those processes. Furthermore, O-ring 250 is not subjected to the mechanical stresses, arcing, and luminescence that washer 230 is subjected to, and therefore does not need to withstand those processes. Furthermore, O-ring 250 is replaceable, whereas washer 230 is not replaceable.

[0097] Thus, there is a significant structural difference between O-ring 250 and washer 230. Also, there is a significant difference between the rigors and stresses to which O-ring 250 is subjected and those to which washer 230 is subjected. Furthermore, O-ring 250 and washer 230 perform different functions. Therefore, O-ring 250 and washer 230 are structurally and functionally different and cannot be compared to each other.

[0098] Moreover, washer 230 is designed to perform the specific functions described above during both the manufacture and use of ESC 200. Thus, while the use of washers may be common in other technical fields, washer 230 is specifically designed to withstand the harsh electrical, chemical, and thermal environments, as well as mechanical stresses, that are unique to ESC 200.

[0099] For example, the ESC 200 is exposed to voltages of approximately several thousand volts during plasma generation. The ESC 200 is heated, cooled, and reheated to temperatures of several hundred degrees during substrate processing. Thus, the washer 230 of the ESC 200 is exposed to extreme temperatures and thermal cycles. Also, reactive species of highly corrosive process gases tend to flow through the through-holes 220 and 222 and expose the coating 234 of the first layer 234-1 of the washer 230 to toxic chemicals of the process gases. Furthermore, the coating 234 of the first layer 234-1 of the washer 230 is also exposed to arcing and light emission (i.e., plasma generated inside the through-holes 220 and 222) as described above. The washer 230 is designed to withstand these extremely harsh environments inherent to the ESC 200 for thousands of hours. The washer 230 withstands these harsh environments despite its small size. In particular, washer 230 is designed to survive these harsh environments after already being subjected to thermal and mechanical stresses during bonding of ceramic plate 204 and base plate 202. As such, washer 230 is different from other washers that may be used in other environments in other technical fields.

[0100] In the examples shown in Figures 2-8, the ceramic plate 204 is shown and described as having orthogonal through holes 222. However, the present disclosure is not limited to ceramic plates 204 having orthogonal through holes 222. In some examples, the ceramic plate 204 may have more complex gas distribution plenums or flow paths than orthogonal through holes 222. For example, as shown and described below with reference to Figures 9 and 10, multiple holes in the ceramic plate 204 may be connected to one through hole 220 in the base plate 202 with one flow path in the ceramic plate 204. The holes in the ceramic plate 204 may have different diameters. The holes in the ceramic plate 204 may penetrate the ceramic plate 204 at various angles. The holes and flow paths may be arranged in the ceramic plate 204 using various other arrangements. Two examples of various other arrangements are shown and described below with reference to Figures 9 and 10.

[0101] Figures 9 and 10 show an example of a ceramic plate with a plenum instead of orthogonal through holes. Elements shown and described above with reference to Figures 2-8 will not be described again for the sake of brevity. Additionally, although not shown, an O-ring 250 may additionally be disposed around the bonding layer 242 in Figures 9 and 10.

[0102] 9 and 10, the ceramic plate 204 includes a plurality of plenums or flow channels (hereinafter, flow channels) 225-1, 225-2, 225-3, and 225-5 (collectively, flow channels 225). The flow channels 225 are passages drilled in the ceramic plate 204 between the top surface 224 and the bottom surface 226 of the ceramic plate 204. Although only four flow channels 225 are shown for illustrative purposes, the ceramic plate 204 may include fewer or more than four flow channels 225. In the bottom surface 226 of the ceramic plate 204, each flow channel 225 has an opening (hole) that aligns with the through hole 220 of the base plate 202. In the top surface 224 of the ceramic plate 204, each flow channel 225 has a plurality of openings (holes) 223-1, 223-2, ..., and 223-12 (collectively, holes 223). Thus, each flow passage 225 connects an opening (hole) in the bottom surface 226 of the ceramic plate 204 to two or more openings (holes) 223 in the top surface 224 of the ceramic plate 204 .

[0103] The flow passages 225 need not be at right angles as shown in FIG. 9. Instead, the flow passages 225 may extend non-orthogonally as shown in FIG. 10. Also, the flow passages 225 and the holes 223 may have equal or unequal diameters. Furthermore, although not shown, one or more of the flow passages 225 may be interconnected. For example, the flow passage 225-1 may be connected to the flow passage 225-2, and the flow passage 225-3 may be connected to the flow passage 225-4. The through holes 222 in the ceramic plate 204 shown in FIGS. 2-8, and the through holes 223 and the flow passages 225 in the ceramic plate 204 shown in FIGS. 9 and 10 may be collectively referred to as passages.

[0104] The foregoing is merely illustrative in nature and is not intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be embodied in various forms. Thus, although the disclosure includes specific embodiments, the true scope of the disclosure should not be so limited, since other variations will become apparent upon review of the drawings, specification, and claims that follow.

[0105] It should be understood that one or more steps in a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Moreover, although each embodiment is described above as having certain features, any one or more of those features described with respect to an embodiment of the present disclosure can be implemented in other embodiments and / or can be implemented in combination with features of other embodiments (even if the combination is not expressly stated). In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of the present disclosure.

[0106] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms such as "connected," "engaged," "coupled," "adjacent," "adjacent," "on," "above," "below," and "disposed." When a relationship between a first element and a second element is described in the above disclosure, unless specified as "direct," the relationship may be a direct relationship in which there are no other intervening elements between the first element and the second element, but it may also be an indirect relationship in which there are one or more intervening elements (spatial or functional) between the first element and the second element. As used herein, the phrase at least one of A, B, and C should be interpreted as meaning a logic using a non-exclusive logical OR (A OR B OR C), and not as meaning "at least one of A, at least one of B, and at least one of C."

[0107] In some embodiments, the controller is part of a system that may be part of the examples above. Such systems may include processing tools, chambers, processing platforms, and / or semiconductor processing equipment with specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics to control pre-, during, and post-processing operations of semiconductor wafers or substrates. This electronics may be called a "controller" and may control various components or sub-components of the system. Depending on the processing requirements and / or type of system, the controller may be programmed to control any process disclosed herein, including supply of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow settings, fluid supply settings, position operation settings, wafer loading and unloading to and from tools and other transport tools, and / or wafer loading and unloading to and from load locks connected or coupled to the specific system.

[0108] In general, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits may include chips in firmware format that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various personalizations (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. In some embodiments, the operational parameters may be part of a recipe defined by a process engineer to accomplish one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or one or more processing steps during the manufacture of a wafer die.

[0109] In some embodiments, the controller may be part of or coupled to a computer that is integrated or coupled with the system, or otherwise networked or combined with the system. For example, the controller may be in the "cloud" that allows remote access of wafer processing, or may be all or part of a fab host computer system. The computer may allow remote access to the system to monitor the progress of a manufacturing operation, review the history of past manufacturing operations, review trends or performance metrics from multiple manufacturing operations, modify parameters of a current process, set up processing steps following a current process, or initiate a new process.

[0110] In some examples, a remote computer (e.g., a server) can provide the process recipe to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that allows for entry or programming of parameters and / or settings that are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool the controller is configured to connect to or control.

[0111] Thus, as discussed above, the controller may be distributed, e.g., by including one or more separate controllers networked together, cooperating toward a common purpose, such as a process or control as described herein, etc. An example of a controller distributed for such purposes would be one or more integrated circuits on the chamber that are located remotely (e.g., at the platform level or as part of a remote computer) and communicate with one or more integrated circuits that cooperate to control a process in the chamber.

[0112] Without being limited thereto, example systems may include plasma etch chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing systems that may be related to or used in the fabrication and / or manufacturing of semiconductor wafers.

[0113] As described above, depending on the processing steps being performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools installed throughout the factory, a main computer, another controller, or tools used to transport materials to and from tool locations and / or load ports in a semiconductor manufacturing factory.

Claims

1. 1. An electrostatic chuck for a substrate processing system, comprising: a base plate of the electrostatic chuck, the base plate including a metallic material and side walls and upper and lower surfaces of the base plate defining a plenum, the base plate further including an inlet in fluid communication with the plenum and a first plurality of through holes extending from the upper surface into the plenum; a ceramic plate of the electrostatic chuck including a second plurality of through holes extending between an upper surface and a lower surface of the ceramic plate; a bonding layer bonding the base plate and the ceramic plate, the bonding layer including a plurality of washers, each washer comprising: a core comprising a third material; a coating of a fourth material surrounding the core; and the washer and the bonding layer have the same height; An inner diameter of the washer matches a diameter of the first and second pluralities of through holes.

2. 2. The electrostatic chuck of claim 1, The electrostatic chuck, wherein the core and the coating are annular and coaxial.

3. 2. The electrostatic chuck of claim 1, the inlet, the plenum, the inner diameter of the washer, and the first and second pluralities of through-holes are in fluid communication with one another.

4. 2. The electrostatic chuck of claim 1, The bonding layer comprises the third material.

5. 2. The electrostatic chuck of claim 1, The electrostatic chuck, wherein the third material comprises a silicone, a urethane, or a flexible epoxy.

6. 2. The electrostatic chuck of claim 1, The fourth material comprises polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA).

7. 2. The electrostatic chuck of claim 1, the coating includes a first layer of the fourth material disposed on an inner diameter of the core and a second layer of the fourth material disposed on an outer diameter of the core.

8. 8. The electrostatic chuck of claim 7, The sum of the thicknesses of the first and second layers is less than or equal to a thickness of the core.

9. 8. The electrostatic chuck of claim 7, a sum of the thicknesses of the first and second layers is greater than or equal to a thickness of the core.

10. 8. The electrostatic chuck of claim 7, The electrostatic chuck, wherein the first layer and the second layer have different thicknesses.

11. 2. The electrostatic chuck of claim 1, The electrostatic chuck, wherein the washer has a diameter of 2 to 20 mm.

12. 2. The electrostatic chuck of claim 1, The electrostatic chuck, wherein the washer has a thickness of 2 to 10 mils (0.0508 to 0.254 mm).

13. 2. The electrostatic chuck of claim 1, the core comprises 30-90% of the thickness of the washer; The electrostatic chuck, wherein the coating comprises 70-10% of the thickness of the washer.

14. 10. The electrostatic chuck of claim 1, further comprising: an O-ring disposed about the bonding layer, the O-ring comprising: a second core comprising the third material; a second coating including the fourth material surrounding the second core; and 1. An electrostatic chuck comprising:

15. 15. The electrostatic chuck of claim 14, The inner diameter of the O-ring is 300 mm. The O-ring has a cross-sectional diameter of 100 to 150 mils (2.54 to 3.81 millimeters).

16. 2. The electrostatic chuck of claim 1, the ceramic plate includes one or more passages, one of the passages connecting one of the second plurality of through holes in the lower surface of the ceramic plate to at least two of the second plurality of through holes in the upper surface of the ceramic plate.

17. 1. An electrostatic chuck for a substrate processing system, comprising: a base plate including side walls and an upper and lower surface defining a plenum, an inlet in fluid communication with the plenum, and a first plurality of through holes extending from the upper surface into the plenum; a ceramic plate including a second plurality of through holes extending through the ceramic plate; a bonding layer bonding the base plate and the ceramic plate, the bonding layer comprising a plurality of washers, each washer including a core and a coating disposed on the core; An inner diameter of the washer matches a diameter of the first and second pluralities of through holes.

18. 20. The electrostatic chuck of claim 17, The electrostatic chuck, wherein the core and the coating are annular and coaxial.

19. 20. The electrostatic chuck of claim 17, the base plate comprises a metallic material; the tie layer and the core comprise a third material; The electrostatic chuck, wherein the coating comprises a polymer material.

20. 20. The electrostatic chuck of claim 17, the base plate comprises a metallic material; the tie layer comprises silicone; the core comprises a silicone, a urethane, or a flexible epoxy; The electrostatic chuck, wherein the coating comprises polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA).

21. 20. The electrostatic chuck of claim 17, The washer and the bonding layer have the same height.

22. 20. The electrostatic chuck of claim 17, The coating partially surrounds the core.

23. 20. The electrostatic chuck of claim 17, The coating completely surrounds the core.

24. 20. The electrostatic chuck of claim 17, the inlet, the plenum, the inner diameter of the washer, and the first and second pluralities of through-holes are in fluid communication with each other.

25. 20. The electrostatic chuck of claim 17, The coating includes a first layer disposed on an inner diameter of the core and a second layer disposed on an outer diameter of the core.

26. 26. The electrostatic chuck of claim 25, The sum of the thicknesses of the first and second layers is less than or equal to a thickness of the core.

27. 26. The electrostatic chuck of claim 25, a sum of the thicknesses of the first and second layers is greater than or equal to a thickness of the core.

28. 26. The electrostatic chuck of claim 25, The electrostatic chuck, wherein the first layer and the second layer have different thicknesses.

29. 20. The electrostatic chuck of claim 17, The electrostatic chuck, wherein the washer has a diameter of 2 to 20 mm.

30. 20. The electrostatic chuck of claim 17, The washer has a thickness of 2 to 10 mils.

31. 20. The electrostatic chuck of claim 17, the core comprises 30-90% of the thickness of the washer; The electrostatic chuck, wherein the coating comprises 70-10% of the thickness of the washer.

32. 20. The electrostatic chuck of claim 17, further comprising: an O-ring disposed about the bonding layer, the O-ring comprising: a second core comprising the same material as the core of the washer; and a second coating surrounding the second core and comprising the same material as the coating of the washer; and 1. An electrostatic chuck comprising:

33. 33. The electrostatic chuck of claim 32, The inner diameter of the O-ring is 300 mm. The O-ring has a cross-sectional diameter of 100 to 150 mils.

34. 20. The electrostatic chuck of claim 17, the ceramic plate includes one or more passages, one of the passages connecting one of the second plurality of through holes in the lower surface of the ceramic plate to at least two of the second plurality of through holes in the upper surface of the ceramic plate.

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