Electrostatic chuck assembly for high-temperature processing

Abstract

We provide a substrate support assembly (also called an electrostatic chuck assembly) that can be used for high-temperature processing. [Solution] In a semiconductor processing chamber, the electrostatic chuck assembly 150 includes a pack 166 and a cooling plate 164. The pack includes an electrically insulating upper pack plate 230 including one or more heating elements and one or more electrodes for electrostatically fixing a substrate, and a lower pack plate 232 joined to the upper pack plate by a metal bond. The lower pack plate includes a plurality of structures distributed on the bottom surface of the lower pack plate at a plurality of different distances from the center of the lower pack plate, each of the plurality of structures housing one of a plurality of fasteners. The cooling plate is joined to the pack by the plurality of fasteners, each of the plurality of fasteners applying substantially equal fastening forces to join the cooling plate to the pack.

Description

Technical Field

[0001] Some embodiments of the present invention generally relate to a substrate support assembly (also referred to as an electrostatic chuck assembly) that can be used for high-temperature processing. Background

[0002] Electrostatic chucks are widely used to hold a substrate (e.g., a semiconductor wafer) during substrate processing in a processing chamber used for various applications (e.g., physical vapor deposition, etching, or chemical vapor deposition). An electrostatic chuck typically includes one or more electrodes embedded within a single chuck body that includes a dielectric or semiconductive ceramic material and can generate an electrostatic clamping region across its entire area.

[0003] Electrostatic chucks offer several advantages over mechanical clamping devices and vacuum chucks. For example, electrostatic chucks can reduce stress-induced cracks caused by mechanical clamping, expose a larger area of the substrate for processing (with little or no edge exclusion), and can be used in low-pressure or high-vacuum environments. Additionally, electrostatic chucks can hold the substrate more uniformly to the chucking surface and can control the substrate temperature more precisely.

[0004] Various processes used in the manufacture of integrated circuits may require high temperatures and / or a wide temperature range for substrate processing. However, electrostatic chucks in etching processes typically operate in a temperature range up to about 120°C. At temperatures above about 120°C, many components of electrostatic chucks will begin to malfunction due to various problems (e.g., de-chucking in AlO electrostatic chucks, plasma erosion by corrosive chemicals, bonding reliability, etc.). Summary

[0005] Some embodiments of the present invention described herein encompass an electrostatic chuck assembly comprising a pack having an electrically insulating upper pack plate including one or more heating elements and one or more electrodes for electrostatically fixing a substrate, and a lower pack plate bonded to the upper pack plate by a metal bond. The lower pack plate includes a plurality of structures distributed on the bottom surface of the lower pack plate at different distances from the center of the lower pack plate, each of which houses a fastener. The electrostatic chuck assembly further includes a cooling plate bonded to the pack by fasteners. Each fastener applies substantially equal fastening force to bond the cooling plate to the pack.

[0006] Some embodiments of the present invention described herein encompass an electrostatic pack comprising an AlN or Al2O3 upper pack plate having one or more heating elements and one or more electrodes for electrostatically fixing a substrate. The electrostatic pack further comprises a lower pack plate bonded to the upper pack plate by a metal bond. The lower pack plate is made of a) molybdenum, b) a SiC porous body fused with an AlSi alloy, or c) a ceramic such as AlN or Al2O3. The lower pack plate further comprises a plurality of structures distributed on the bottom surface of the lower pack plate at different distances from the center of the lower pack plate, each of which houses a fastener.

[0007] Some embodiments of the present invention described herein encompass a method for manufacturing an electrostatic chuck assembly. The method includes the step of forming a plurality of structures within a lower pack plate. The method further includes the step of joining the lower pack plate to an upper pack plate by metal bonding to form a pack, wherein the upper pack plate includes one or more heating elements and one or more electrodes for electrostatically fixing a substrate. The method further includes the step of placing at least one of a perfluoropolymer (PFP) gasket or a PFP O-ring on the upper surface of at least a portion of the cooling plate. The method further includes the step of inserting one of a plurality of fasteners into each of the plurality of structures formed within the lower pack plate. The method further includes the step of joining the cooling plate to the pack by tightening the plurality of fasteners. The plurality of fasteners can be tightened substantially equally to apply substantially equal fastening forces to join the cooling plate to the pack. [Brief explanation of the drawing]

[0008] The present invention is shown in the drawings of the accompanying drawings as examples, not as limitations, and similar reference numerals indicate similar elements. It should be noted that different references to “one” or “one” embodiment in this disclosure do not necessarily refer to the same embodiment, and such references mean at least one. [Figure 1] This is a cross-sectional side view of one embodiment of a processing chamber. [Figure 2] An exploded view of one embodiment of a substrate support assembly is shown. [Figure 3] A cross-sectional top view of one embodiment of an electrostatic chuck assembly is shown. [Figure 4] A cross-sectional side view of one embodiment of an electrostatic chuck assembly is shown. [Figure 5] This is a cross-sectional side view of another embodiment of an electrostatic chuck assembly. [Figure 6] This document illustrates one embodiment of the process for manufacturing an electrostatic chuck assembly. Detailed description of the embodiment

[0009] Embodiments of the present invention provide a substrate support assembly and an electrostatic chuck assembly including a pack coupled to a cooling plate by a set of fasteners. Multiple fasteners are used to secure the pack to the cooling plate. The multiple fasteners are positioned at different distances from the center of the pack. In one embodiment, a first set of fasteners is positioned at a first radius from the center of the pack, and a second set of fasteners is positioned at a second radius from the center of the pack. The multiple fasteners can be distributed substantially uniformly over the upper surface or the entire surface of the cooling plate, evenly distributing the fastening force to bond the pack to the cooling plate. The fasteners can all be tightened by the same amount to ensure that the fastening force applied by each fastener is substantially the same. This promotes uniform heat transfer characteristics between the pack and the cooling plate on top of the pack.

[0010] In one embodiment, the electrostatic chuck assembly includes a pack having an electrically insulating upper pack plate bonded to a lower pack plate by a metal joint. The metal joint may be an aluminum joint, an AlSi alloy joint, or another metal joint. The upper pack plate includes one or more heating elements and one or more electrodes for electrostatically fixing a substrate. The lower pack plate includes a plurality of structures distributed on the bottom surface of the lower pack plate at different distances from the center of the lower pack plate. Each of the structures accommodates one of a plurality of fasteners. The electrostatic chuck assembly further includes a cooling plate bonded to the pack by fasteners. The cooling plate includes a base portion (called a cooling base) and a spring-biased inner heat sink connected to the base portion by a plurality of springs, the plurality of springs applying a force that presses the inner heat sink against the pack. Each fastener applies substantially equal fastening forces to bond the cooling plate to the pack (e.g., to bond the base portion of the cooling plate to the pack). These substantially equal fastening forces can promote uniform heat transfer between the cooling plate and the pack. Furthermore, the spring-driven inner heatsink can also promote uniform heat transfer between the cooling plate and the pack.

[0011] Figure 1 is a cross-sectional view of one embodiment of a semiconductor processing chamber 100 in which an electrostatic chuck assembly 150 is located. The electrostatic chuck assembly 150 includes an electrostatic pack (pack 166) having an upper pack plate coupled to a lower pack plate, as will be described in more detail below. The pack 166 is coupled to a cooling plate by a plurality of fasteners, as will be described in more detail below.

[0012] The processing chamber 100 includes a chamber body 102 and a lid 104 that enclose an internal volume 106. The chamber body 102 can be manufactured from aluminum, stainless steel, or other suitable material. The chamber body 102 generally includes side walls 108 and a bottom 110. An outer liner 116 is positioned adjacent to the side walls 108 and can protect the chamber body 102. The outer liner 116 can be manufactured and / or coated from a plasma-resistant or halogen-resistant gas-resistant material. In one embodiment, the outer liner 116 is manufactured from aluminum oxide. In another embodiment, the outer liner 116 is manufactured from yttria, yttrium alloy, or an oxide thereof, or coated with yttria, yttrium alloy, or an oxide thereof.

[0013] The exhaust port 126 can be defined within the chamber body 102, and the internal volume 106 can be coupled to the pump system 128. The pump system 128 may include one or more pumps and throttle valves used to exhaust and regulate the pressure of the internal volume 106 of the processing chamber 100.

[0014] The lid 104 can be supported on the side wall 108 of the chamber body 102. The lid 104 can be opened to allow access to the internal volume 106 of the processing chamber 100, and when closed, it can provide a seal for the processing chamber. A gas panel 158 can be coupled to the processing chamber 100 to supply processing gases and / or cleaning gases to the internal volume 106 via a gas distribution assembly 130 which is part of the lid 104. Examples of processing gases include halogen-containing gases (in particular, C2F6, SF6, SiCl4, HBr, NF3, CF4, CHF3, CH2F3, Cl2, and SiF4, etc.) and other gases (e.g., O2 or N2O) that can be used for processing within the processing chamber. Examples of carrier gases include N2, He, Ar, and other gases that are inert to the processing gases (e.g., non-reactive gases). The gas distribution assembly 130 has a plurality of openings 132 on its downstream side so that the gas flow can be directed to the surface of the substrate 144. Additionally or alternatively, the gas distribution assembly 130 may have a central hole through which gas is supplied via a ceramic gas nozzle. The gas distribution assembly 130 may be manufactured and / or coated with a ceramic material (e.g., silicon carbide, yttrium oxide, etc.) to provide resistance to halogen-containing chemicals and prevent corrosion of the gas distribution assembly 130.

[0015] The substrate support assembly 148 is placed in the internal volume 106 of the processing chamber 100 below the gas distribution assembly 130. The substrate support assembly 148 holds the substrate 144 during processing. The inner liner 118 may be coated on the periphery of the substrate support assembly 148. The inner liner 118 can be made of a halogen-resistant gas-resistant material (e.g., one discussed with reference to the outer liner 116). In one embodiment, the inner liner 118 can be manufactured from the same material as the outer liner 116.

[0016] In one embodiment, the substrate support assembly 148 includes a mounting plate 162 that supports a base 152 and an electrostatic chuck assembly 150. In one embodiment, the electrostatic chuck assembly 150 further includes a cooling plate and a thermally conductive base, as referred to herein, coupled to an electrostatic pack (hereinafter referred to herein as pack 166) by a plurality of fasteners. The electrostatic chuck assembly 150 described in the embodiment includes an electrostatic chuck 164. The electrostatic chuck assembly 150 described in the embodiment can be used for Johnson-Larbec and / or Coulomb electrostatic chucking.

[0017] In one embodiment, the protective ring 146 is positioned on the outer circumference of the pack 166 and on a portion of the pack 166. In one embodiment, the pack 166 is coated with a protective layer 136. Alternatively, the pack 166 may not be coated with the protective layer 136. The protective layer 136 is made of ceramics (e.g., Y2O3 (yttria or yttrium oxide), Y4Al2O9 (YAM), Al2O3 (alumina), Y3Al5O 12 (YAG), YAlO3 (YAP), quartz, SiC (silicon carbide), Si3N4 (silicon nitride), Sialon, AlN (aluminum nitride), AlON (aluminum oxynitride), TiO2 (titania), ZrO2 (zirconia), TiC (titanium carbide), ZrC (zirconium carbide), TiN (titanium nitride), TiCN (titanium carbonitride), Y2O3-stabilized ZrO2 (YSZ), etc. The protective layer can also be a ceramic composite material (e.g., Y3Al5O distributed within an Al2O3 matrix). 12 The protective layer may also be a solid solution of Y2O3-ZrO2 or SiC-Si3N4. The protective layer may also be a ceramic composite material containing a solid solution of yttrium oxide (also known as yttria and Y2O3). For example, the protective layer may be a solid solution of compound Y4Al2O9 (YAM) and Y 2-x Zr xThe material may be a ceramic composite consisting of O3 (Y2O3-ZrO2 solid solution). The pure yttrium oxide and yttrium oxide-containing solid solution may be doped with one or more of the following oxides: ZrO2, Al2O3, SiO2, B2O3, Er2O3, Nd2O3, Nb2O5, CeO2, Sm2O3, Yb2O3, or other oxides. Alternatively, the protective layer may be sapphire or MgAlON.

[0018] Pack 166 includes an upper bonding plate (not shown) and a lower bonding plate (not shown) joined by a metal bonding. The upper pack plate is suitable for semiconductor processing at temperatures of 180°C or higher (e.g., 10°C). 14 It can be a dielectric or electrically insulating material having an electrical resistivity greater than ohms-meter. In one embodiment, the upper pack plate is made of a material usable from about 20°C to about 500°C. In one embodiment, the upper pack plate is AlN. The AlN upper pack plate may be doped or undoped. For example, AlN can be doped with samarium oxide (Sm2O3), cerium oxide (CeO2), titanium dioxide (TiO2), or a transition metal oxide. In one embodiment, the upper pack plate is Al2O3. The Al2O3 upper pack plate may be doped or undoped. For example, Al2O3 can be doped with titanium dioxide (TiO2) or a transition metal oxide.

[0019] The lower pack plate may have a coefficient of thermal expansion that matches the coefficient of thermal expansion of the upper pack plate. In one embodiment, the lower pack plate is a SiC porous body impregnated with an AlSi alloy (called AlSiSiC). Alternatively, the lower pack plate may be AlN or Al2O3. In one embodiment, the lower pack plate is undoped AlN or undoped Al2O3. In one embodiment, the lower pack plate is made of the same material as the upper pack plate. The AlSiSiC material, AlN, or Al2O3 can be used, for example, in a reactive etching environment or an inert environment.

[0020] In one embodiment, the lower pack plate is molybdenum. For example, molybdenum can be used when pack 166 is used in an inert environment. An example of an inert environment is an environment in which an inert gas (e.g., Ar, O2, N, etc.) is flowed inside. For example, molybdenum can be used when pack 166 chucks a substrate for metal deposition. Molybdenum may also be used for the lower pack plate for applications in corrosive environments (e.g., etching applications). In such embodiments, after the lower pack plate is bonded to the upper pack plate, the exposed surface of the lower pack plate may be coated with a plasma-resistant coating. The plasma-resistant coating may be applied via a plasma spraying process. The plasma-resistant coating can cover, for example, the side walls of the lower pack plate and any exposed horizontal steps of the lower pack plate. In one embodiment, the plasma-resistant coating is Al2O3. Alternatively, the plasma-resistant coating may be Y2O3 or a Y2O3-containing oxide. Alternatively, the plasma-resistant coating may be any of the materials described with respect to the protective layer 136.

[0021] The attachment plate 162 is coupled to the bottom 110 of the chamber body 102 and includes passages for routing utilities (e.g., fluid, power lines, sensor leads, etc.) to the cooling plate 164 and the pack 166. The cooling plate 164 and / or the pack 166 can include one or more optional embedded heating elements 176, an optional embedded thermal isolator 174, and / or optional conduits 168, 170, and can control the lateral temperature profile of the substrate support assembly 148. In one embodiment, a thermal gasket 138 is disposed on at least a portion of the cooling plate 164.

[0022] The conduits 168, 170 can be fluid-coupled to a fluid source 172 that circulates temperature-regulating fluid through the conduits 168, 170. In one embodiment, an embedded thermal isolator 174 can be disposed between the conduits 168, 170. The embedded heating element 176 is regulated by a heater power supply 178. The conduits 168, 170 and the embedded heating element 176 are utilized to control the temperature of the pack 166, thereby heating and / or cooling the pack 166 and the substrate (e.g., wafer) being processed. In one embodiment, the pack 166 includes two separate heating zones that can maintain different temperatures. In another embodiment, the pack 166 includes four different heating zones that can maintain different temperatures. The temperatures of the electrostatic pack 166 and the heat conduction base 164 can be monitored using a plurality of temperature sensors 190, 192 that can be monitored using a controller 195.

[0023] The pack 166 can further include a plurality of gas passages (e.g., grooves, mesas, and other surface structures) that can be formed on the upper surface of the pack 166. The gas passages can be fluid-coupled to a source of heat transfer (or backside) gas (e.g., He) through holes drilled into the pack 166. During operation, the backside gas is supplied to the gas passages at a controlled pressure to improve heat transfer between the pack 166 and the substrate 144.

[0024] In one embodiment, the chuck 166 includes at least one clamping electrode 180 controlled by a chucking power supply 182. The clamping electrode 180 (also referred to as a chucking electrode) can be further coupled to one or more RF power supplies 184, 186 via a matching circuit 188 for maintaining a plasma formed from a process gas and / or other gases within the processing chamber 100. The one or more RF power supplies 184, 186 can generally generate RF signals having a frequency of from about 50 kHz to about 3 GHz and a power of up to about 10,000 watts. In one embodiment, an RF signal is applied to a metal base, an alternating current (AC) is applied to a heater, and a direct current (DC) is applied to the clamping electrode 180.

[0025] FIG. 2 shows an exploded view of one embodiment of the substrate support assembly 148. The substrate support assembly 148 shows an exploded view of an electrostatic chuck assembly 150 including a pack 166 and a pedestal 152. The electrostatic chuck assembly 150 includes a pack 166 and a cooling plate 164 attached to the pack 166. As shown, an O-ring 240 can be vulcanized to the cooling plate 164 along the periphery of the upper surface of the cooling plate 164. Alternatively, the O-ring may be disposed without being vulcanized to the upper surface of the cooling plate 164. In this specification, embodiments are described with reference to O-rings and gaskets vulcanized to at least a portion of the cooling plate 164. However, it should be understood that the O-ring and / or gasket may alternatively be vulcanized to the lower pack plate. Alternatively, the O-ring and / or gasket may not be vulcanized to any surface. In one embodiment, the O-ring 240 is an O-ring made of perfluoropolymer (PFP). Alternatively, other types of high-temperature O-rings may be used. In one embodiment, a thermally insulating high-temperature O-ring is used. The O-ring 240 can be a stepped O-ring having a first stage of a first thickness and a second stage of a second thickness. This can facilitate uniform tightening of the fastener by dramatically increasing the amount of force used to tighten the fastener after the set compression amount of the PFP O-ring 240.

[0026] Additional O-rings (not shown) may also be vulcanized on the upper surface of the cooling plate 164 around the hole 280 in the center of the cooling plate 164 through which the cable passes. Other smaller O-rings may also be vulcanized on the cooling plate 164 around other openings, around the lift pins, etc. Alternatively, a gasket (e.g., a PFP gasket) may be vulcanized on the upper surface of the cooling plate 164. Examples of PFPs that can be used for the gasket or O-ring 240 are DuPont's ECCtreme, DuPont's KALREZ, and Daikin's DUPRA. The O-ring 240 or gasket provides a vacuum seal between the internal volume of the chamber and the internal volume within the electrostatic chuck assembly 150. The internal volume within the electrostatic chuck assembly 150 includes an open space within the base 152 for routing conduits and wiring.

[0027] The cooling plate 164 further includes a number of structures 242 into which fasteners are inserted. If gaskets are used, the gaskets may have notches in each of the structures 242. Fasteners extend through each of the structures 242 and are attached to additional portions of fasteners (or additional fasteners) that are inserted into additional structures formed within the pack 166. For example, bolts may extend through the structures 242 in the cooling plate 164 and be screwed into nuts located within the structures of the pack 166. Each structure 242 in the cooling plate 164 may be aligned with a similar structure (not shown) in the lower pack plate 232 of the pack 166.

[0028] The pack 166 has a disc-like shape with an annular periphery that can substantially match the shape and size of the substrate 144 placed thereon. The top surface of the pack 166 may have an outer ring 216, a plurality of mesas 206, 210, and channels 208, 212 between the mesas 210. The pack 166 includes an upper pack plate 230 joined to a lower pack plate 232 by metal bonding. In one embodiment, the upper pack plate 230 can be made of an electrically insulating ceramic material. Preferred examples of ceramic materials include aluminum nitride (AlN) and alumina (Al2O3).

[0029] In one embodiment, the material used for the lower pack plate 232 is appropriately selected such that the coefficient of thermal expansion (CTE) of the lower pack plate 232 material substantially matches that of the electrically insulating upper pack plate 230 material, thereby minimizing the CTE mismatch and avoiding thermomechanical stress that could damage the pack 166 during thermal cycling. In one embodiment, the lower pack plate 232 is molybdenum. In one embodiment, the lower pack plate is alumina. In one embodiment, the lower pack plate is AlN.

[0030] In one embodiment, a conductive metal matrix composite (MMC) material is used for the lower pack plate 232. The MMC material comprises a metal matrix and reinforcing material embedded and dispersed throughout the matrix. The metal matrix may include a single metal or two or more metals or metal alloys. Usable metals include, but are not limited to, aluminum (Al), magnesium (Mg), titanium (Ti), cobalt (Co), cobalt-nickel alloy (CoNi), nickel (Ni), chromium (Cr), gold (Au), silver (Ag), or various combinations thereof. The reinforcing material can be selected to provide the desired structural strength of the MMC, or it may be selected to provide desired values ​​for other properties of the MMC, such as thermal conductivity and CTE. Examples of usable reinforcing materials include silicon (Si), carbon (C), or silicon carbide (SiC), but other materials may also be used.

[0031] The MMC material for the lower pack plate 232 is preferably selected to provide the desired conductivity and substantially match the CTE of the upper pack plate 230 material over the operating temperature range of the electrostatic chuck assembly 150. In one embodiment, the temperature can be in the range of about 20°C to about 500°C. In one embodiment, matching the CTE is based on selecting the MMC material such that the MMC material includes at least one material also used in the material of the upper pack plate 230. In one embodiment, the upper pack plate 230 contains AlN. In one embodiment, the MMC material contains a SiC porous body fused with an AlSi alloy.

[0032] The constituent materials and composition percentages of the MCC can be selected to provide an engineering material that satisfies the desired design objectives. For example, by appropriately selecting the MCC material to closely match the CTEs of the lower pack plate 232 and the upper pack plate 230, the thermomechanical stress at the interface between the lower pack plate 232 and the upper pack plate 230 is reduced.

[0033] The lower pack plate 232 may include a number of structures (not shown) for receiving fasteners. The structures may be distributed substantially uniformly across the entire surface of the lower pack plate 232 and may include a first set of structures at a first distance from the center of the lower pack plate 232 and a second set of structures at a second distance from the center of the lower pack plate 232.

[0034] The cooling plate 164 mounted beneath the pack 166 may have a disc-shaped main portion 224 and an annular flange extending outward from the main portion 224 and positioned on a base 152. In one embodiment, the cooling plate 164 may be formed from a metal (e.g., aluminum or stainless steel) or other suitable material. Alternatively, the cooling plate 164 may be manufactured from composite ceramics (e.g., aluminum-silicon alloy fused SiC or molybdenum) to match the thermal expansion coefficient of the pack 166. The cooling plate 164 should provide good strength and durability as well as heat transfer properties.

[0035] Figure 3 shows a cross-sectional top view of one embodiment of pack 166. As shown, pack 166 has a radius R3 which can be substantially the same as the radius of a substrate or wafer that can be supported by pack 166. Pack 166 further includes a plurality of structures 305. The structures can be matched with similar structures in a cooling plate to which pack 166 is mounted. Each structure 305 accommodates fasteners. For example, bolts (e.g., stainless steel bolts, galvanized steel bolts, etc.) can be placed in each structure such that the bolt heads are inside an opening large enough to accommodate the bolt heads, and the bolt shafts extend outward from the bottom surface of pack 166. The bolts can be fastened to nuts located in the corresponding structures in the cooling plate. Alternatively, the structures 305 can be sized to accommodate nuts and may include holes that can receive the bolt shafts accommodated by the corresponding structures in the cooling plate. In another example, a helical insert (e.g., Heli-Coil™) or other threaded insert (e.g., press-fit insert, mold-in insert, captive nut, etc.) can be inserted into one or more structures to add threaded holes. Bolts positioned inside the cooling plate and protruding from the cooling plate may then be screwed into the threaded insert to secure the cooling plate to the pack. Alternatively, the threaded insert may be used inside the cooling plate.

[0036] The structure 305 can be made slightly larger than the size of the fastener to accommodate a larger thermal expansion coefficient of the fastener. In one embodiment, the fastener is sized such that it does not exert force on the structure when the fastener is heated to 500 or 600°C.

[0037] As shown in the figure, the pack 166 may contain multiple sets of structures 305. Each set of structures 305 can be arranged at equal intervals from the center of the pack 166 at a specific radius or distance. For example, as shown in the figure, the first set of structures 305 is arranged at radius R1, and the second set of structures 305 is arranged at radius R2. Additional sets of structures may also be arranged at additional radii.

[0038] In one embodiment, the structures are arranged to generate a uniform load on the pack 166. In one embodiment, the structures are arranged so that bolts are located approximately every 30 to 70 square centimeters (e.g., every 50 square centimeters). In one embodiment, three sets of structures are used for a 12-inch pack 166. The first set of structures may be located approximately 4 inches from the center of the pack 166 and may contain approximately 4 structures. The second set of structures may be located approximately 6 inches from the center of the pack 166 and may contain approximately 6 structures. The third set of structures may be located approximately 8 inches from the center of the pack 166 and may contain approximately 8 structures. In one embodiment, the pack 166 contains approximately 8 to 24 structures arranged in sets at 2 to 3 different radii, with each structure housing a fastener.

[0039] Figure 4 shows a cross-sectional side view of one embodiment of an electrostatic chuck assembly 150. The electrostatic chuck assembly 150 includes a pack 166 comprising an upper pack plate 230 and a lower pack plate 232 joined together by a metal joint 450. In one embodiment, diffusion bonding is used as the method of metal bonding, but other bonding methods may also be used. In one embodiment, the upper pack plate 230 and the lower pack plate 232 include an aluminum-containing material (e.g., AlN or Al2O3). The metal joint 450 may include an "intermediate layer" of aluminum foil placed in the bonding region between the upper pack plate 230 and the lower pack plate 232. By applying pressure and heat, a diffusion bond can be formed between the aluminum foil and the upper pack plate 230, and between the aluminum foil and the lower pack plate 232. In another embodiment, the diffusion bond may be formed using other intermediate layer material selected based on the material used for the upper pack plate 230 and the lower pack plate 232. In another embodiment, the upper pack plate 230 may be directly bonded to the lower pack plate 232 using direct diffusion bonding, in which case the intermediate layer is not used to form the bond.

[0040] The plasma-resistant high-temperature O-ring 445 can be made of perfluoropolymer (PFP). The O-ring 445 may be a PFP having an inorganic additive (e.g., SiC). The O-ring may be replaceable. When the O-ring 445 deteriorates, it can be removed and a new O-ring can be stretched over the upper pack plate 230 and positioned around the pack 166 at the interface between the upper pack plate 230 and the lower pack plate 232. The O-ring 445 can protect the metal joint 450 from plasma erosion.

[0041] The upper pack plate 230 includes a mesa 210, a channel 212, and an outer ring 216. The upper pack plate 230 includes a clamp electrode 180 and one or more heating elements 176. The clamp electrode 180 is coupled to a chucking power supply 182 and to an RF plasma power supply 184 and an RF bias power supply 186 via a matching circuit 188. The upper pack plate 230 and the lower pack plate 232 may additionally include gas supply holes (not shown) through which a gas supply source 440 pumps backside gas (e.g., He).

[0042] The upper pack plate 230 can have a thickness of approximately 3 to 25 mm. In one embodiment, the upper pack plate 230 has a thickness of approximately 3 mm. The clamp electrode 180 can be positioned approximately 1 mm from the top surface of the upper pack plate 230, and the heating element 176 can be positioned approximately 1 mm below the clamp electrode 180. The heating element 176 can be a screen-printed heating element having a thickness of approximately 10 to 200 microns. Alternatively, the heating element may be a resistance coil using approximately 1 to 3 mm of the thickness of the upper pack plate 230. In such an embodiment, the upper pack plate 230 can have a minimum thickness of approximately 5 mm. In one embodiment, the lower pack plate 232 has a thickness of approximately 8 to 25 mm.

[0043] The heating element 176 is electrically connected to a heater power supply 178 for heating the upper pack plate 230. The upper pack plate 230 may include an electrically insulating material (e.g., AlN). The lower pack plate 232 and the upper pack plate 232 can be made of the same material. In one embodiment, the lower pack plate 232 is made of a different material than the material used for the upper pack plate 230. In one embodiment, the lower pack plate 232 is made of a metal matrix composite material. In one embodiment, the metal matrix composite material includes aluminum and silicon. In one embodiment, the metal matrix composite material is a SiC porous body fused with an AlSi alloy.

[0044] The lower pack plate 232 is coupled to a cooling plate 164 having one or more conduits 170 (also referred to herein as cooling channels) that are in fluid communication with a fluid source 172, thereby transferring heat. The cooling plate 164 is coupled to the pack 166 by a plurality of fasteners 405. The fasteners 405 may be screw fasteners (e.g., a pair of nuts and bolts). As shown, the lower pack plate 232 includes a plurality of structures 430 for housing the fasteners 405. The cooling plate 164 similarly includes a plurality of structures 432 for housing the fasteners 405. In one embodiment, the structures are bolt holes with counterbore holes. As shown, the structures 430 are through-shaped structures that extend through the lower pack plate 232. Alternatively, the structures 430 may not be through-shaped. In one embodiment, the structures 430 are slots for housing T-shaped bolt heads or rectangular nuts that can be inserted into the slots and then rotated 90 degrees. In one embodiment, the fastener includes a washer, graphoil, aluminum foil, or other load-distributing material that evenly distributes the force from the fastener head to the structure.

[0045] In one embodiment (as illustrated), the PFP O-ring 410 is vulcanized (or otherwise positioned) on the cooling plate 164 around it. Alternatively, the PFP O-ring 410 may be vulcanized on the bottom surface of the lower cooling plate 232. The fasteners 405 can be tightened to compress the PFP O-ring 410. All the fasteners 405 are tightened with approximately the same force so that the separation portion 415 between the pack 166 and the cooling plate is substantially identical (uniform) across the entire interface between the pack 166 and the cooling plate 164. This ensures that the heat transfer characteristics between the cooling plate 164 and the pack 166 are uniform. In one embodiment, the separation portion 415 is about 2 to 10 mils. For example, if the PFP O-ring 410 is used without a graphoil layer, the separation portion may be 2 to 10 mils. If a graphoil layer is used with the PFP O-ring 410, the separation portion may be about 10 to 40 mils. A larger separation section reduces heat transfer and causes the interface between the pack 166 and the cooling plate 164 to act as a thermal choke. In one embodiment, a conductive gas can be flowed into the separation section 415 to improve heat transfer between the pack 166 and the cooling plate 164.

[0046] The separation section 415 minimizes the contact area between the pack 166 and the cooling plate 164. Furthermore, by maintaining a thermal choke between the pack 166 and the cooling plate 164, the pack 166 can be maintained at a much higher temperature than the cooling plate 164. For example, in some embodiments, the pack 166 can be heated to a temperature of 180-300 degrees Celsius, while the cooling plate 164 can be maintained at a temperature of less than approximately 120 degrees Celsius. The pack 166 and the cooling plate 164 expand or contract independently during the thermal cycle.

[0047] The separator 415 can function as a thermal choke by restricting the heat conduction path from the heated pack 166 to the cooled cooling plate 164. In a vacuum environment, unless a heat transfer medium is supplied, heat transfer may be primarily a radiative process. Since the pack 166 may be placed in a vacuum environment during substrate processing, the heat generated by the heating element 176 can be transferred more inefficiently across the separator 415. Therefore, the heat flux flowing from the pack 166 to the cooling plate 164 can be controlled by adjusting the separator and / or other factors that affect heat transfer. To provide efficient heating of the substrate, it is desirable to limit the amount of heat conducted away from the upper pack plate 230.

[0048] In one embodiment (not shown), a graphoil layer is placed between the pack 166 and the cooling plate 164 around the PFP O-ring 410. The graphoil can have a thickness of about 10 to 40 mils. A fastener 405 can be tightened to compress the graphoil layer and the PFP O-ring 410. The graphoil can be thermally conductive and can improve heat transfer between the pack 166 and the cooling plate 164.

[0049] In one embodiment (not shown), the cooling plate 164 includes a base portion on which a PFP O-ring 410 can be vulcanized. The cooling plate 164 may further include a spring-biased inner heat sink connected to the base portion by one or more springs. The springs apply a force that presses the inner heat sink against the pack 166. The surface of the heat sink may have a predetermined roughness and / or surface shape (e.g., mesa) that controls the heat transfer characteristics between the pack 166 and the heat sink. Furthermore, the material of the heat sink may affect the heat transfer characteristics. For example, an aluminum heat sink will transfer heat better than a stainless steel heat sink. In one embodiment, the heat sink includes a graphoil layer on the upper surface of the heat sink.

[0050] Figure 5 shows a cross-sectional side view of another embodiment of the electrostatic chuck assembly 505. In one embodiment, the electrostatic chuck assembly 505 corresponds to the electrostatic chuck assembly 150 in Figures 1 and 2. The electrostatic chuck assembly 505 includes an electrostatic pack 510, which consists of an upper pack plate 515 and a lower pack plate 520. In one embodiment, the electrostatic pack 510 corresponds to the pack 166 in Figure 3. In one embodiment, the upper pack plate 515 is joined to the lower pack plate 520 by a metal joint 550. In one embodiment, diffusion bonding is used as the method of metal bonding. However, metal bonding can also be produced using other bonding methods.

[0051] The upper pack plate 515 is made of an electrically insulating (dielectric) ceramic (e.g., AlN or Al2O3). The upper pack plate 515 includes a clamp electrode 527 and one or more heating elements 529. The clamp electrode 527 is coupled to a chucking power supply (not shown) and can be coupled to an RF plasma power supply (not shown) and an RF bias power supply (not shown) via a matching circuit (not shown). The heating element 529 is electrically connected to a heater power supply (not shown) for heating the upper pack plate 515.

[0052] The upper pack plate 515 can have a thickness of approximately 3 to 10 mm. In one embodiment, the upper pack plate 515 has a thickness of approximately 3 to 5 mm. The clamp electrode 527 can be located approximately 0.3 to 1 mm from the top surface of the upper pack plate 515, and the heating element 529 can be located approximately 2 mm below the clamp electrode 527. The heating element 529 can be a screen-printed heating element having a thickness of approximately 10 to 200 microns. Alternatively, the heating element 529 may be a resistance coil using approximately 1 to 3 mm of the thickness of the upper pack plate 515. In such embodiments, the upper pack plate 515 can have a minimum thickness of approximately 5 mm.

[0053] The lower pack plate 520 is made of a material having a coefficient of thermal expansion (CTE) similar to or matching that of the upper pack plate 515. The material used for the lower pack plate 520 is appropriately selected so that the CTE of the lower pack plate 520 material substantially matches that of the electrically insulating upper pack plate 515 material, thereby minimizing the CTE mismatch and avoiding thermomechanical stress that could damage the electrostatic chuck assembly 505 during thermal cycling. Therefore, if the upper pack plate 515 is AlN, the lower pack plate 520 can also be AlN. Similarly, if the upper pack plate is Al2O3, the lower pack plate 520 can also be Al2O3. Other materials (e.g., molybdenum, or conductive metal matrix composites (MMCs) such as AlSiSiC) may also be used for the lower pack plate 520.

[0054] In one embodiment, the lower pack plate 520 has a thickness of approximately 8 to 25 mm. In a further embodiment, the lower pack plate 520 has a thickness of approximately 8 to 20 mm. In a further embodiment, the lower pack plate 520 has a thickness of approximately 12 mm.

[0055] In one embodiment, the lower pack plate 520 has a roughened outer wall coated with a plasma-resistant ceramic coating (not shown). The plasma-resistant ceramic coating can correspond to any of the plasma-resistant ceramic coatings discussed with reference to the protective layer 136.

[0056] The metal joint 550 may include an "intermediate layer" of aluminum foil placed in the joint area between the upper pack plate 515 and the lower pack plate 520. By applying pressure and heat, a diffusion bond can be formed between the aluminum foil and the upper pack plate 515, and between the aluminum foil and the lower pack plate 520. In other embodiments, the diffusion bond may be formed using other intermediate layer material selected based on the materials used for the upper pack plate 515 and the lower pack plate 520. In one embodiment, the metal joint 550 has a thickness of about 0.2 to 0.3 mm. In one embodiment, the upper pack plate 515 may be directly joined to the lower pack plate 520 using a direct diffusion bond, in which case the intermediate layer is not used to form the bond.

[0057] The upper pack plate 515 may have a larger diameter than the lower pack plate 520. In one embodiment, the upper pack plate 515 and the lower pack plate 520 each have a diameter of approximately 300 mm.

[0058] The edges of the cooling plate 594 may have a diameter similar to that of the upper pack plate 515. A plasma-resistant high-temperature O-ring 545 may be placed between the upper pack plate 515 and the base portion 595 of the cooling plate 594. This O-ring 545 can provide a vacuum seal between the inside of the electrostatic chuck assembly 505 and the processing chamber. The O-ring 545 may be manufactured from a perfluoropolymer (PFP). In one embodiment, the O-ring 545 is a PFP having an inorganic additive (e.g., SiC). The O-ring 545 may be replaceable. When the O-ring 545 deteriorates, it can be removed, and a new O-ring can be stretched over the upper pack plate 515 and placed around the upper pack plate 515 at the interface between the upper pack plate 515 and the cooling plate 594. The O-ring 545 can protect the metal joint 550 from plasma erosion.

[0059] The cooling plate 594 includes a base portion (also called a cooling base) 595 and a heat sink (e.g., an internal heat sink) 536. The heat sink 536 can be coupled to the base portion 595 by one or more springs 570 that act to press the heat sink 536 against the lower pack plate 520, and in one embodiment, the springs 570 are coil springs. The springs 570 apply a force that presses the heat sink 536 against the electrostatic pack 510. The heat sink 536 may have one or more conduits 535 (also called cooling channels herein) that are in fluid communication with a fluid source (not shown). The surface of the heat sink 536 may have a predetermined roughness and / or surface structure (e.g., a mesa) that affects the heat transfer characteristics between the electrostatic pack 510 and the heat sink 536. Furthermore, the material of the heat sink 536 can affect the heat transfer characteristics. For example, an aluminum heat sink 536 will transfer heat better than a stainless steel heat sink 536. In one embodiment, the mounting plate 540 is positioned below the cooling plate 594 and coupled to the cooling plate 594.

[0060] The lower pack plate 520 may include a number of structures 524 for receiving fasteners 526. The cooling plate 594 may similarly include a number of structures 528 for accommodating fasteners 526. Alternatively, or additionally, the mounting plate 540 may include a number of structures for receiving fasteners. The structures 528 may be aligned vertically with the structures 524. The structures 524, 528 may be through-shaped through the lower pack plate 520 and the cooling plate 594. Alternatively, the structures 524, 528 may not be through-shaped. In one embodiment, the structures 524, 528 are bolt holes with counterbore holes. In one embodiment, the structures 524, 528 are slots for accommodating T-shaped bolt heads or rectangular nuts that can be inserted into the slots and then rotated 90 degrees.

[0061] In one embodiment, the cooling plate 594 is coupled to the electrostatic pack 510 by a plurality of fasteners 526 inserted into the structures 528, 524. The fasteners 526 may be stainless steel, galvanized steel, molybdenum, or other metals. The fasteners 526 may be threaded fasteners (e.g., a pair of nuts and bolts). In one embodiment, the fasteners 526 include washers, graphoil, aluminum foil, or other load-diffusing materials to distribute force uniformly from the head of the fastener to the fastener. In one embodiment, a helical insert (e.g., Heli-Coil (trademark)) or other threaded insert (e.g., press-fit insert, mold-in insert, captive nut, etc.) may be inserted into the structure 524 to add threaded holes thereto. Bolts positioned inside the cooling plate 594 (e.g., inside the structure 524 within the base portion 595 of the cooling plate 594) and protruding from the cooling plate 594 can then be screwed into the threaded inserts to secure the cooling plate to the pack. Alternatively, threaded inserts may be used within the cooling plate.

[0062] In one embodiment, a captive nut, molded insert, press-fit insert, or other threaded insert is positioned inside the structure 524. In a further embodiment, at least a portion of the threaded insert is brazed before insertion into the structure 524. Alternatively, a metal foil may be placed between the threaded insert and the surface of the structure 524. A metal bonding procedure (e.g., diffusion bonding) may then be performed to secure the threaded insert to the structure 524. This can provide increased durability for increased force application during assembly.

[0063] The base portion 595 of the heat sink 536 and / or the cooling plate 594 can absorb heat from the electrostatic pack 510. In one embodiment (as shown in the figure), a low thermal conductivity gasket 525 is placed on the heat sink 536. The low thermal conductivity gasket 525 can be, for example, a PFP gasket that is vulcanized on (or placed on) the heat sink 536. In one embodiment, the low thermal conductivity gasket has a thermal conductivity of about 0.2 watts / meter Kelvin (W / (m·K)) or less. The fasteners 526 can be tightened with substantially the same force, and the spring 570 can press the heat sink 536 against the lower pack plate 520 so as to uniformly compress the low thermal conductivity gasket 525. The low thermal conductivity gasket 525 can reduce heat transfer and function as a thermal choke.

[0064] In one embodiment, a graphoil layer (not shown) is placed on a low thermal conductivity gasket 525. The graphoil can have a thickness of about 10 to 40 mils. Fasteners 526 and / or springs 570 can compress the graphoil layer and the low thermal conductivity gasket 525. The graphoil can be thermally conductive and can improve lateral heat transfer across the heat sink 536.

[0065] By maintaining a thermal choke between the electrostatic pack 510 and the cooling plate 594, the electrostatic pack 510 can be maintained at a much higher temperature than the cooling plate 594. For example, in some embodiments, the electrostatic pack 510 can be heated to a temperature of 200-300 degrees Celsius, while the cooling plate 594 can be maintained at a temperature of less than approximately 120 degrees Celsius. In one embodiment, the electrostatic pack 510 can be heated to a temperature of approximately 250 degrees Celsius while the cooling plate 594 is maintained at a temperature of less than approximately 60 degrees Celsius. Thus, in the embodiment, a delta of up to 190 degrees Celsius is maintained between the electrostatic pack 510 and the cooling plate 594. The electrostatic pack 510 and the cooling plate 594 expand or contract independently and freely during the thermal cycle.

[0066] In some embodiments, it may be desirable to supply an RF signal to a supported substrate through the electrostatic pack 510 during processing. In one embodiment, to facilitate the transmission of such an RF signal through the electrostatic pack 510, a conductive gasket called an RF gasket 590 is placed on the base portion 595 of the cooling plate 594. The RF gasket is 10 -3 It has an electrical conductivity of the order of ohms-meters or higher and can maintain its spring action at temperatures up to approximately 300°C. In one embodiment, the RF gasket is Inconel (a nickel alloy containing chromium and iron) coated with gold, copper, or silver. The RF gasket 590 can electrically connect the base portion 595 of the cooling plate 594 to the lower pack plate 520.

[0067] In embodiments where the lower pack plate 520 has low conductivity (for example, when the lower pack plate 520 is AlN or Al2O3), a hole can be drilled in the lower pack plate 520 where it contacts the RF gasket. The hole can then be filled with a highly conductive material (for example, a metal (for example, 10) -3The holes may be filled with metal rods having conductivity on the order of ohms-meters or higher. For example, the holes can be filled with aluminum, tungsten, copper, nickel, molybdenum, silver, gold, etc. Thus, the conductive path 522 is formed within the lower pack plate 520, and the RF signal can be electrically connected to the metal junction 550. In one embodiment, a conductive pad is formed on the surface of the lower pack plate 520 around the conductive path 522. This ensures good electrical contact with the metal junction 550 and the RF gasket 590. In one embodiment, a shallow recess is drilled in the lower pack plate 520 centered on the hole formed for the conductive path 522. The shallow recess may also be filled with metal or other conductive material. In the illustrated example, the RF gasket 590 and the conductive path 522 are located outside the heat sink 536 (for example, further away from the center of the electrostatic chuck assembly 505 than the heat sink 536). Alternatively, the RF gasket 590 and the conductive path 522 may be formed closer to the center of the electrostatic chuck assembly 505.

[0068] In one embodiment, the conductive path between the metal joint 550 and the RF gasket 590 is formed by coating the outer wall of the lower pack plate 520 with a metal layer. The metal layer can be aluminum, copper, gold, silver, an alloy thereof, or another metal. The top and bottom of the lower pack plate 520 may also be coated with a metal layer near the outer wall to ensure good electrical contact. In such an embodiment, the RF gasket 590 can be positioned near the outer wall of the lower pack plate 520.

[0069] In another embodiment, the conductive path between the metal joint 550 and the RF gasket 590 is formed by coating the walls of the central hole in the lower pack plate 520 with a metal layer. The metal layer can be aluminum, copper, gold, silver, an alloy thereof, or another metal. The top and bottom of the lower pack plate 520 may also be covered with a metal layer near the outer walls to ensure good electrical contact. In such embodiments, the RF gasket 590 can be positioned near the center of the lower pack plate 520.

[0070] In one embodiment, the thermal spacer 585 is positioned on the base portion 595 of the cooling plate 594 (for example, adjacent to the RF gasket 590). The thermal spacer 585 can be used to ensure that the base portion 594 of the cooling plate 595 does not come into contact with the lower pack plate 520. In one embodiment, an O-ring 580 is positioned adjacent to the thermal spacer 585. In one embodiment, the O-ring 580 may be a PFP O-ring. The O-ring 580 can be used to facilitate a vacuum seal.

[0071] In one embodiment, one or more gas holes 532, 542 are drilled in the cooling plate 594, the lower pack plate 520, and the upper pack plate 515. The gas holes 532, 542 can be used to supply backside gas (e.g., helium) to the back surface of the chucked substrate. In one embodiment, the upper pack plate 515 includes a gas hole 532 that terminates with a porous plug 534. The gas hole 532 can be a through-hole counterbore with a larger diameter hole so that the porous plug 534 can be inserted into the larger diameter hole. The porous plug 534 can be a porous ceramic such as AlN or Al2O3. The porous plug 534 can prevent arc discharge and / or prevent plasma from being generated in the electrostatic pack 505. The porous plug can have a porosity between about 30% and about 60%.

[0072] In one embodiment, the heat sink 536 includes a hole, and the base portion 595 of the cooling plate 594 includes a projection 544 extending through the hole in the heat sink 536. The hole 542 may be drilled into the projection 544 (for example, at the center of the projection 544). In one embodiment, an O-ring 538 is positioned on top of the projection 544. The fastener 526 can compress the O-ring 538 when tightened. The O-ring 538 may be the same type of O-ring as O-ring 545 and / or O-ring 580.

[0073] Figure 6 shows one embodiment of process 600 for manufacturing an electrostatic chuck assembly. In block 605 of process 600, a structure is formed within a lower pack plate. The lower pack plate can be an AlSiSiC plate, an AlN plate, an Al2O3 plate, or a molybdenum plate. The structure formed within the lower pack plate may include a structure for housing fasteners. Furthermore, one or more gas holes can be drilled in the lower pack plate. Furthermore, one or more other holes can be drilled in the lower pack plate and filled with a metal rod or other conductive material to provide a conductive path for RF signals. In one embodiment, shallow holes are drilled at both ends of one or more other holes in the lower pack plate and filled with metal or other conductive material. The upper pack plate can also be machined to form one or more gas supply holes. In one embodiment, the gas supply holes in the upper pack plate are counterbored and the counterbores are filled with porous plugs.

[0074] In block 610, the lower pack plate is metal-bonded to the upper pack plate to form a pack. The upper pack plate can be an electrically insulating material (dielectric) with embedded heating elements and clamp electrodes. In one embodiment, the metal bond is formed by placing a metal foil of Al or AlSi alloy between the upper pack plate and the lower pack plate. In one embodiment, the metal foil can be about 50 microns thick. Pressure and heat may be applied to form a diffusion bond between the metal foil and the upper and lower pack plates.

[0075] In one embodiment, the threaded insert is placed within a structure formed in the lower pack plate before the upper pack plate is joined to the lower pack plate. In one embodiment, the threaded insert is brazed. In another embodiment, metal foil is placed within the structure before the threaded insert is placed into the structure. During the metal bonding process, the threaded insert may be joined to the lower pack plate by metal bonding.

[0076] In block 615, a PFP gasket or O-ring is placed on the upper surface of the cooling plate. In one embodiment, the PFP gasket or O-ring is vulcanized on the upper surface of the cooling plate. The cooling plate may be, for example, an aluminum or aluminum alloy cooling plate with multiple channels for the flow of cooling fluid. The cooling plate may also have internal structures. The structures within the cooling plate and the structures within the lower pack plate may each accommodate fasteners (e.g., bolts and / or nuts). In one embodiment, the cooling plate includes a base and a heat sink. The PFP gasket may be placed on the heat sink, and in some embodiments, the structures may be formed within the base. In one embodiment, a graphoil layer is formed on top of the PFP gasket.

[0077] In block 620, the fasteners are inserted into the structure within the lower pack plate and / or the cooling plate. In one embodiment, the fasteners (or at least a portion of the fasteners) are inserted into the lower pack plate before the lower pack plate is joined to the upper pack plate. In such embodiments, the fasteners can be permanently embedded within the pack. In block 625, the pack is joined to the cooling plate by tightening the fasteners (for example, by passing bolts protruding from the structure within the lower pack plate into nuts within the structure within the cooling plate).

[0078] The foregoing description provides numerous specific details, such as examples of specific systems, components, and methods, in order to provide a good understanding of some embodiments of the present invention. However, it will be apparent to those skilled in the art that at least some embodiments of the present invention can be implemented without these specific details. In other examples, well-known components or methods are either not described in detail or are presented in simple block diagram form so as not to unnecessarily obscure the present invention. Thus, the specific details described are merely illustrative. It will be understood that specific implementations may differ from these exemplary details but still fall within the scope of the present invention.

[0079] Throughout this specification, any reference to “one embodiment” or “one embodiment” means that a particular configuration, structure, or characteristic described in relation to that embodiment is included in at least one embodiment. Therefore, occurrences of the phrase “in one embodiment” or “in one embodiment” in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the term “or” is intended to mean inclusive, not exclusive. Where the terms “about” or “approximately” are used herein, this is intended to mean that the nominal values ​​presented are accurate within ±10%.

[0080] Although the operations of the Method described herein are illustrated and described in a specific order, the order of operations of each Method can be changed so that certain operations are performed in reverse order, or so that certain operations are performed at least partially concurrently with other operations. In another embodiment, the instructions or sub-operations of different operations may be intermittent and / or alternating. In one embodiment, multiple metal bonding operations are performed as a single step.

[0081] It should be understood that the above description is illustrative and not limited. Many other embodiments will become apparent to those skilled in the art by reading and understanding the above description. Therefore, the scope of the present invention should be determined by referring to the appended claims together with the entire scope of equivalents that such claims grant rights to.

Claims

1. An electrostatic chuck assembly, It's a pack, An electrically insulating upper pack plate including one or more heating elements and one or more electrodes for electrostatically fixing a substrate, A lower pack plate joined to an upper pack plate by metal bonding, The lower pack plate includes multiple structures distributed across the lower pack plate at multiple different distances from the center of the lower pack plate. Each of the multiple structures includes a pack containing a lower pack plate that houses one of the multiple fasteners, A cooling plate connected to the lower pack plate by multiple fasteners, The conductive path of the lower pack plate, An electrostatic chuck assembly comprising a conductive gasket between a lower pack plate and a cooling plate, the conductive gasket in contact with a conductive path.

2. The electrostatic chuck assembly according to claim 1, wherein the conductive path includes a hole filled with a conductive material.

3. The electrostatic chuck assembly according to any one of claims 1 to 2, further comprising an interface between the pack and the cooling plate, which functions as a thermal choke configured to maintain a maximum temperature difference of approximately 190°C between the cooling plate and the substrate.

4. The cooling plate further includes at least one of a gasket or an O-ring positioned on the upper surface of the cooling plate at the outer circumference of the cooling plate, Each of the fasteners applies a fastening force to connect the cooling plate to the pack, compressing at least one of the gasket or O-ring, maintaining an even separation between the cooling plate and the lower pack plate, thereby promoting uniform heat transfer between the cooling plate and the lower pack plate. The electrostatic chuck assembly according to claim 1, wherein the separation between the cooling plate and the lower pack plate is 2 to 40 mils.

5. An electrostatic chuck assembly, It's a pack, An electrically insulating upper pack plate including one or more heating elements and one or more electrodes for electrostatically fixing a substrate, A lower pack plate joined to an upper pack plate by metal bonding, The lower pack plate includes multiple structures distributed across the lower pack plate at multiple different distances from the center of the lower pack plate. Each of the multiple structures includes a pack containing a lower pack plate that houses one of the multiple fasteners, A cooling plate connected to the lower pack plate by multiple fasteners, The cooling plate includes at least one of a gasket or an O-ring positioned on the upper surface of the cooling plate at the outer circumference of the cooling plate, Each of the fasteners applies a fastening force to connect the cooling plate to the pack, compressing at least one of the gasket or O-ring, maintaining an even separation between the cooling plate and the lower pack plate, thereby promoting uniform heat transfer between the cooling plate and the lower pack plate. An electrostatic chuck assembly with a separation section between the cooling plate and the lower pack plate that is 2 to 40 mils.

6. The electrostatic chuck assembly according to claim 5, further comprising a conductive path between the upper part of the lower pack plate and the bottom part of the lower pack plate.

7. The electrostatic chuck assembly according to claim 6, wherein the conductive path includes a hole filled with a conductive material.

8. The electrostatic chuck assembly according to claim 6 or 7, further comprising a conductive gasket between the lower pack plate and the cooling plate, the conductive gasket in contact with a conductive path.

9. The electrostatic chuck assembly according to any one of claims 4 to 8, wherein the electrostatic chuck assembly includes an O-ring, and the O-ring is a high-temperature O-ring.

10. The electrostatic chuck assembly according to any one of claims 4 to 8, wherein the electrostatic chuck assembly includes a gasket, the gasket being a low thermal conductivity gasket that acts as a thermal choke between the cooling plate and the pack.

11. The cooling plate includes a heatsink. The electrostatic chuck assembly according to claim 10, further comprising a flexible graphite sheet layer on a gasket, which improves lateral heat transfer across the heat sink.

12. The electrostatic chuck assembly according to any one of claims 10 to 11, wherein the low thermal conductivity gasket includes a gasket made of perfluoropolymer (PFP).

13. The upper pack plate contains AlN. The electrostatic chuck assembly according to any one of claims 1 to 11, wherein the lower pack plate comprises one of a) AlN, b) molybdenum, or c) a SiC porous body impregnated with an AlSi alloy.

14. The upper pack plate is made of aluminum. ２ O ３ Includes, The lower pack plate is made of aluminum. ２ O ３ An electrostatic chuck assembly according to any one of claims 1 to 11, comprising:

15. It is an electrostatic pack, AlN or Al containing one or more heating elements and one or more electrodes for electrostatically fixing the substrate. ２ O ３ The upper pack plate made of, A lower pack plate joined to an upper pack plate by metal bonding, The lower pack plate consists of a) molybdenum, b) a porous SiC body impregnated with AlSi alloy, c) AlN or d) Al ２ O ３ Including one of the following, The lower pack plate further includes multiple structures distributed on the bottom surface of the lower pack plate at multiple different distances from the center of the lower pack plate. Each of the multiple structures has a lower pack plate that houses one of the multiple fasteners, An electrostatic pack including a conductive path between the top and bottom of the lower pack plate.

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