Electrostatic chuck using metal bonding

Abstract

An electrostatic chuck (ESC) for a plasma processing chamber and a method of manufacturing the ESC are described. In one example, a substrate support assembly includes a ceramic bottom plate having a heater element therein. The substrate support assembly also includes a ceramic top plate having an electrode therein. Between the ceramic top plate and the ceramic bottom plate is a metal layer. The ceramic top plate is in direct contact with the metal layer, and the metal layer is in direct contact with the ceramic bottom plate.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 171,916, filed February 9, 2021, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate to the field of reactors or plasma processing chambers, and more particularly to electrostatic chucks using metallurgical bonding. [Background technology]

[0003] Processing systems, such as reactors or plasma reactors, are used to form devices on substrates, such as semiconductor wafers or transparent substrates. Often, the substrate is held on a support for processing. The substrate may be held on the support by vacuum, gravity, electrostatic force, or other suitable techniques. During processing, a precursor gas or gas mixture in the chamber is energized (e.g., excited) into a plasma by applying power, such as radio frequency (RF) power, to electrodes in the chamber from one or more power supplies coupled to the electrodes. The excited gas or gas mixture reacts to form a layer of material on the surface of the substrate. This layer may be, for example, a passivation layer, a gate insulator, a buffer layer, and / or an etch stop layer.

[0004] Electrostatic chucks (ESCs) are used in semiconductor and other industries to hold workpieces, such as substrates, on a support during substrate processing. A typical ESC may include a base, an electrically insulating layer disposed on the base, and one or more electrodes embedded in the electrically insulating layer. The ESC may be equipped with an embedded electric heater and may be fluidly coupled to a heat transfer gas source to control the substrate temperature during processing. During use, the ESC is fixed to a support within a processing chamber. The electrodes within the ESC are electrically biased with respect to a substrate placed on the ESC by a voltage source. Opposite electrostatic charges accumulate on the electrodes of the ESC and the surface of the substrate, and charge flow between them is prevented by an insulating layer. An electrostatic force resulting from the accumulation of electrostatic charge holds the substrate to the ESC during substrate processing. Summary of the Invention

[0005] Embodiments of the present disclosure include an electrostatic chuck (ESC) for a plasma processing chamber and a method of manufacturing an ESC.

[0006] In one embodiment, the substrate support assembly includes a ceramic bottom plate having a heater element therein. The substrate support assembly also includes a ceramic top plate having an electrode therein. A metal layer is between the ceramic top plate and the ceramic bottom plate. The ceramic top plate is in direct contact with the metal layer, which is in direct contact with the ceramic bottom plate.

[0007] In another embodiment, a method of manufacturing a substrate support assembly includes forming a ceramic bottom plate having a heater element therein. The method also includes forming a ceramic top plate having an electrode therein. The method also includes bonding the ceramic top plate to the ceramic bottom plate with a metal layer between the ceramic top plate and the ceramic bottom plate. The ceramic top plate is in direct contact with the metal layer, and the metal layer is in direct contact with the ceramic bottom plate.

[0008] In another embodiment, a deposition system includes a chamber, a plasma source within or coupled to the chamber, and an electrostatic chuck within the chamber. The electrostatic chuck includes a ceramic bottom plate having a heater element therein. The substrate support assembly also includes a ceramic top plate having an electrode therein. A metal layer is between the ceramic top plate and the ceramic bottom plate. The ceramic top plate is in direct contact with the metal layer, and the metal layer is in direct contact with the ceramic bottom plate. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of an electrostatic chuck (ESC) according to an embodiment of the present disclosure. [Figure 2A] 1A-1C are cross-sectional views illustrating an operation in a method of manufacturing an electrostatic chuck (ESC) according to an embodiment of the present disclosure. [Figure 2B] 1A-1C are cross-sectional views illustrating an operation in a method of manufacturing an electrostatic chuck (ESC) according to an embodiment of the present disclosure. [Figure 2C] 1A-1C are cross-sectional views illustrating an operation in a method of manufacturing an electrostatic chuck (ESC) according to an embodiment of the present disclosure. [Figure 3A] FIG. 10 is a cross-sectional view of another electrostatic chuck (ESC) in accordance with another embodiment of the present disclosure. [Figure 3B] FIG. 10 is a cross-sectional view of another electrostatic chuck (ESC) in accordance with another embodiment of the present disclosure. [Figure 4] 1 is a schematic cross-sectional view of a processing chamber including a substrate support assembly according to an embodiment of the present disclosure. [Figure 5] 1 is a schematic partial cross-sectional view of a processing chamber including a substrate support assembly according to an embodiment of the present disclosure. [Figure 6] 1 is a block diagram of an exemplary computer system according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] An electrostatic chuck (ESC) for a plasma processing chamber and a method for manufacturing the ESC are described. In the following description, numerous specific details are set forth, such as components and material regions of the electrostatic chuck, to provide a comprehensive understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known aspects, such as plasma enhanced chemical vapor deposition (PECVD) or plasma enhanced atomic layer deposition (PEALD) processes, are not described in detail to avoid unnecessarily obscuring embodiments of the present disclosure. Furthermore, it should be understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

[0011] One or more embodiments are directed to a new approach to fabricating ESCs without affecting their resistivity. Embodiments can be implemented to fabricate ESCs without an associated change in resistivity.

[0012] To provide context, diffusion bonding is generally a costly process, and heating to such high temperatures affects the thermal and / or electrical properties of the ceramic. State-of-the-art ESCs are typically fabricated using two diffusion bonds: one between the top and bottom plates and another between the joined plates and the shaft. It should be understood that using too many diffusion bonds formed at high temperatures can affect the resistivity of the ceramic. Embodiments described herein can be implemented to eliminate the need for diffusion bonds or at least limit the number of diffusion bonds in an ESC to one diffusion bond. Embodiments can be implemented to ensure that the resistivity of the top plate does not change (or changes only minimally) during fabrication of the ESC. Embodiments can be implemented to advantageously reduce the manufacturing cost of the ESC by eliminating at least one high-temperature operation from the manufacturing scheme. Embodiments can be implemented to preserve or retain the as-sintered resistivity of the top ceramic material.

[0013] Advantages of implementing one or more embodiments disclosed herein may include enabling the fabrication of ESCs without altering resistivity. Advantages may include reducing the cost of fabricating ESCs. Advantages may include enabling the possibility of fabricating ESCs in a manner that maintains the electrical properties of components included in the ESC.

[0014] Compared to state-of-the-art approaches that may involve two diffusion bonds, in accordance with embodiments of the present disclosure, aluminum bonding is used instead of the typical diffusion bonding (or organic bonding). For example, aluminum bonding can be used between the top and bottom plates, between the bottom plate and the shaft, or between both the top and bottom plates and the bottom plate and the shaft; all three of the top, middle, and shaft are aluminum bonded.

[0015] According to one or more embodiments of the present disclosure, manufacturing operations for producing an ESC without losing good electrical properties may include: (1) fabricating an upper ESC with brazed high-voltage connection(s), (2) fabricating a bottom plate with heater(s), (3) fabricating a shaft, (4) diffusion bonding the shaft to the bottom plate, (5) brazing electrical connections to the bottom plate, (6) metallurgical (e.g., aluminum) bonding the upper and lower plates, and (7) installing an insulating tube. It should be understood that the above list of operations may be performed in the order presented or in a different order. It should also be understood that not all operations may be performed and / or that additional operations other than those listed above may be performed.

[0016] As an example of a manufactured ESC, FIG. 1 shows a cross-sectional view of an electrostatic chuck (ESC) according to an embodiment of the present disclosure.

[0017] Referring to FIG. 1 , the ESC 100 includes a ceramic bottom plate 102 having a heater coil 104 therein. The heater coil 104 can be coupled to a heater connection 105 (it should be understood that in another embodiment, for tape-cast AlN or AlN plate materials used in ESC fabrication, the heater electrode is screen-printed). A ceramic shaft 106 is bonded to the bottom surface of the ceramic bottom plate 102. The ESC 100 also includes a ceramic top plate 108. The ceramic top plate 108 has an ESC (clamp) electrode 110 or electrode assembly therein. A metal layer 112 bonds the ceramic top plate 108 to the top surface of the ceramic bottom plate 102. A thermocouple 114 extends through an opening 115 in the ceramic bottom plate 102 and the metal layer 112. A high-voltage insulator 116 extends through the opening 115 in the ceramic bottom plate 102 and the metal layer 112 to accommodate the ESC high-voltage connection 118.

[0018] 1 , according to an embodiment of the present disclosure, a substrate support assembly 100 includes a ceramic bottom plate 102 having a heater element 104 therein. The substrate support assembly 100 also includes a ceramic top plate 108 having an electrode 110 therein. Between the ceramic top plate 108 and the ceramic bottom plate 102 is a metal layer 112. The ceramic top plate 108 is in direct contact with the metal layer 112, and the metal layer 112 is in direct contact with the ceramic bottom plate 102.

[0019] In another embodiment, the ceramic top plate and ceramic bottom plate are bonded at 1400 degrees Celsius using a metal, metal alloy, or ceramic adhesive after the ceramic shaft is diffusion bonded to the ceramic bottom plate. In another embodiment, a metal, alloy, or ceramic bonding material is used to bond the top plate, bottom plate, and shaft components.

[0020] In some embodiments, the metal layer 112 provides for the incorporation of a metallurgical bond in place of a diffusion bond between the ceramics, which can change the resistivity of the upper ceramic during diffusion bond formation. In one embodiment, the metal layer 112 is a metal foil, such as an aluminum foil. In one such embodiment, the metal layer 112 is an aluminum foil impregnated with approximately 2% to 20% Si (e.g., as an atomic % of the total foil composition), with the remainder being aluminum, or is essentially all aluminum (i.e., the aluminum foil includes silicon having an atomic concentration ranging from 2% to 20% of the aluminum foil). In some embodiments, the metal layer 112 is pre-patterned to include openings 115 and / or additional openings, for example, to accommodate lift pins or the like. In one embodiment, the metal layer 112 is an aluminum foil having a thickness ranging from 50 to 500 microns, and can be approximately 250 microns. In some embodiments, the metal layer 112 is an aluminum foil that is cleaned prior to incorporation into the ESC manufacturing process, for example, to remove a passivation layer prior to bonding. In one embodiment, the metal layer 112 is aluminum foil, which can withstand corrosive processes, such as chlorine-based processes, without etching or degrading the metal layer 112 during use of the ESC. However, when used in non-chlorine-based processes, the metal layer 112 may be composed of a silver-copper alloy, for example, with or without titanium additions. In one embodiment, the metal layer 112 is bonded to the top plate 108 and the bottom plate 102 at temperatures below 600 degrees Celsius, more specifically below 300 degrees Celsius. It should be appreciated that higher ESC operating temperatures, such as 650 degrees Celsius, can be used if the metallurgical bonding is performed with a high-temperature metallurgical bond, such as a silver-copper or gold-nickel temperature, much lower than 1400 degrees Celsius but well above the 650 degrees Celsius operating temperature.

[0021] In some embodiments, the bond 120 between the ceramic shaft 106 and the ceramic bottom plate 102 is a diffusion bond formed from a ceramic-to-ceramic bond. In other embodiments, the bond 120 is an inorganic or organic bond, and the ceramic shaft 106 is attached to the ceramic bottom plate 102 by any suitable technique, such as adhesive bonding, the use of mechanical fasteners, brazing, welding, etc. However, according to embodiments of the present disclosure, the bond 120 is alternatively a metallic bond, such as a bond formed by including a metallic layer (similar to layer 112) between the ceramic shaft 106 and the ceramic bottom plate 102, an example of which is described in connection with FIG. 3A .

[0022] Referring to the ceramic top plate 108 having the ESC (clamp) electrode 110 therein, in one embodiment, the body of the top plate can be formed by sintering a ceramic material, such as aluminum nitride (AlN) or aluminum oxide powder, or other suitable material. An RF mesh can be embedded in the body. The RF mesh can have electrical connections extending through the bottom surface of the body. The RF mesh can include molybdenum or another suitable metallic material mesh. In one embodiment, the mesh is approximately 125 microns in diameter. The material can be sintered to form a unitary structure. In one embodiment, the electrode 110 is fabricated from a metallic material, such as molybdenum, that can have a thermal expansion coefficient similar to that of the body. In one embodiment, the ceramic top plate 108 is targeted to maintain a temperature below 350 degrees Celsius, for example, between 150 and 300 degrees Celsius, and can include dopants to optimize operation within such a target temperature range.

[0023] The clamping electrode 110 may include at least a first electrode and a second electrode. During operation, a negative charge may be applied to the first electrode and a positive charge may be applied to the second electrode, or vice versa, to generate an electrostatic force. During chucking, the electrostatic force generated by the electrodes holds a substrate placed thereon in a fixed position. When power is turned off from the power supply, the charge present at the interface between the electrodes may persist for an extended period of time. To release a substrate held on the electrostatic chuck, a short power pulse with reverse polarity may be applied to the electrodes to remove the charge present at the interface.

[0024] The electrode assembly can be formed from a metal rod, sheet, stick, or foil, and can be pre-formed, pre-cast, or pre-fabricated and placed on the surface of the insulating base during the manufacture of the electrostatic chuck. Alternatively, a metal deposition process can be performed and deposited directly on the top surface of the insulating base to form the electrode assembly. Suitable deposition processes can include PVD, CVD, plating, inkjet printing, rubber stamping, screen printing, or aerosol printing processes. Additionally, a metal paste / wire can be formed on the top surface of the insulating base. The metal paste / wire can initially be a liquid, paste, or metal gel, which can be patterned on the surface of the object in a pattern to form electrode fingers with different configurations or dimensions on the top surface of the insulating base.

[0025] Regarding the ceramic bottom plate 102, in one embodiment, the ceramic bottom plate 108 is targeted to maintain temperatures up to 650 degrees Celsius and may include dopants to optimize operation within such target temperature range. In one embodiment, the ceramic bottom plate 102 has an aluminum nitride composition that is different from the aluminum nitride composition of the ceramic top plate 108. The heating element 104 included in the ceramic bottom plate 102 can use any suitable heating technique, such as resistive heating or inductive heating. The heating element 104 may be constructed from a resistive metal, a resistive metal alloy, or a combination of the two. Suitable materials for the heating element may include materials with high thermal resistance, such as tungsten, molybdenum, or titanium. In one embodiment, the heating element 104 is constructed from molybdenum wire. The heating element 104 may also be fabricated from a material with thermal properties, e.g., a thermal expansion coefficient, that substantially match those of at least one or both of the aluminum nitride bodies to reduce stresses caused by mismatched thermal expansion.

[0026] The ceramic shaft 106 may include a material having thermal properties, e.g., a thermal expansion coefficient, that substantially matches that of the ceramic bottom plate 102. Suitable ceramic materials for fabricating the shaft 106 may include, but are not limited to, aluminum nitride, glass, silicon carbide, aluminum oxide, yttrium-containing materials, yttrium oxide (YO), yttrium aluminum garnet (YAG), titanium oxide (TiO), or titanium nitride (TiN). A bonding process may be performed to fuse the ceramic shaft 106 and the ceramic bottom plate 102 together as a whole, thereby forming a unitary component of the electrostatic chuck. It should be noted that various types of bonding processes may be utilized, including, but not limited to, annealing, sintering, bonding, slumping, or diffusion bonding. In one example, the bonding process is an annealing process. The annealing process may be performed by any suitable hardening or annealing tool, such as an oven, a furnace, a thermal plate, a rapid thermal processing (RTP) chamber, a spike annealing, or a laser annealing chamber. The annealing process can be carried out at a temperature between about 1200 degrees Celsius and about 2500 degrees Celsius to aid in consolidation to form a unitary part.

[0027] 2A-2C illustrate cross-sectional views depicting various operations in a method of manufacturing an electrostatic chuck (ESC) according to an embodiment of the present disclosure. It should be understood that the order of the manufacturing operations is exemplary and for illustrative purposes only, and that other orders of the manufacturing operations may be performed.

[0028] Referring to FIG. 2A, a ceramic shaft 106 is bonded to a ceramic bottom plate 102. In one embodiment, the ceramic bottom plate is formed from sintered aluminum nitride (AlN) powder and metal coil. The bond between the shaft and bottom plate is formed as a diffusion bond and is formed at temperatures greater than 1400 degrees Celsius. The ceramic bottom plate 102 may be solid at this stage (as shown) or may already have patterned openings (e.g., for central high voltage (HV) and thermocouple connections and / or lift pins). It should also be appreciated that the ceramic top plate may include other features, such as upper grooves (or channels) to accommodate cooling gas flow, which coincide with the gas passageways in the bonding layer and top ceramic, so that gas can be delivered to the back of the wafer or for edge purging (e.g., as described below in connection with FIG. 3B).

[0029] 2B and 2C, the ceramic top plate 108 is fabricated and then bonded to the ceramic bottom plate with a metal layer 112 (which may already include one or more patterned openings 113). In one embodiment, the metal layer 112 is bonded to the ceramic bottom plate 102 at the same time that the metal layer 112 is bonded to the ceramic top plate 108. In another embodiment, the metal layer 112 is first bonded to the ceramic top plate 108, and then the ceramic top plate / metal layer 112 pair is bonded to the ceramic bottom plate 102. In another embodiment, the metal layer 112 is first bonded to the ceramic bottom plate 102, and then the ceramic bottom plate / metal layer 112 pair is bonded to the ceramic top plate 108. In any event, in one embodiment, the ceramic top plate is formed from sintered aluminum nitride (AlN) powder and a metal mesh.

[0030] 2B and 2C 。 In some embodiments, if the openings are not pre-formed in the ceramic bottom plate 102, they can be manufactured following the acts of Figures 2B and 2C. In some embodiments, connections to the top plate (e.g., thermocouples, HV connections) can be made to the top plate first, or may be made later. In one embodiment, such connections are made by brazing the ceramic top plate before bonding it to the ceramic bottom plate.

[0031] 1 and 2A-2C, according to an embodiment of the present disclosure, a method 100 or 200 of manufacturing a substrate support assembly includes forming a ceramic bottom plate 102 having a heater element 104 therein. The method also includes forming a ceramic top plate 108 having an electrode 110 therein. The method also includes bonding the ceramic top plate 108 to the ceramic bottom plate 102 with a metal layer 112 between the ceramic top plate 108 and the ceramic bottom plate 102. The ceramic top plate 108 is in direct contact with the metal layer 112, and the metal layer 112 is in direct contact with the ceramic bottom plate 102.

[0032] In one embodiment, bonding the ceramic top plate 108 to the ceramic bottom plate 102 with the metal layer 112 includes heating the ceramic bottom plate 102, the metal layer 112, and the ceramic top plate 108 to a temperature less than 600 degrees Celsius. In one embodiment, the metal layer 112 is aluminum foil, and the method includes cleaning a surface of the aluminum foil to remove a passivation layer of the aluminum foil before bonding the ceramic top plate 108 to the ceramic bottom plate 102 with the metal layer 112.

[0033] In some embodiments, the method further includes bonding the ceramic shaft 106 to the ceramic bottom plate 102 on a side of the ceramic bottom plate 102 opposite the metal layer 112 before bonding the ceramic top plate 108 to the ceramic bottom plate 102 with the metal layer. In one such embodiment, bonding the ceramic shaft 106 to the ceramic bottom plate 102 includes heating the ceramic shaft 106 and the ceramic bottom plate 102 to a temperature greater than 1400 degrees Celsius to form a diffusion bond between the ceramic shaft 106 and the ceramic bottom plate 102.

[0034] In another embodiment, bonding the ceramic shaft 106 to the ceramic bottom plate 102 includes coupling the ceramic shaft 106 to the ceramic bottom plate 102 by a second metal layer. The ceramic bottom plate 102 is in direct contact with the second metal layer, which is in direct contact with the ceramic shaft 106. By way of example, Figure 3A illustrates a cross-sectional view of another electrostatic chuck (ESC) according to another embodiment of the present disclosure.

[0035] 3A , ESC 300 includes similar features as those described above in connection with ESC 100 (where like numbers represent the same or similar functionality). However, compared to ESC 100, ESC 300 includes a second metal layer 302 between ceramic shaft 106 and ceramic bottom plate 102. In one embodiment, metal layer 302 has similar or identical properties as those described above for metal layer 112. While shown without openings yet formed, it should be understood that ceramic bottom plate 102 can include openings therein that align with openings 113 upon alignment.

[0036] In one embodiment, metal layer 302 is used to bond ceramic shaft 106 to ceramic bottom plate 102 before metal layer 112 is used to bond ceramic top plate 108 to ceramic bottom plate 102. In another embodiment, metal layer 112 is used to bond ceramic top plate 108 to ceramic bottom plate 102, and then metal layer 302 is used to bond ceramic shaft 106 to ceramic bottom plate 102. In another embodiment, metal layer 112 is used to bond ceramic top plate 108 to ceramic bottom plate 102, and metal layer 302 is used to bond ceramic shaft 106 to ceramic bottom plate 102 at the same time. In an alternative embodiment, ESCs are fabricated using metal layer 302 but not metal layer 112.

[0037] As another example of a manufactured ESC, FIG. 3B shows a cross-sectional view of another electrostatic chuck (ESC) according to another embodiment of the present disclosure.

[0038] Referring to FIG. 3B , an ESC 350 for supporting a substrate 399 includes a ceramic bottom plate 352 having a heater coil 354 therein. The heater coil 354 can be coupled to a heater connection 355 (it should be understood that in another embodiment, for tape-cast AlN or AlN plate materials used in ESC fabrication, the heater electrode is screen-printed). A ceramic shaft 356 is bonded to the bottom surface of the ceramic bottom plate 352. The ESC 350 also includes a ceramic top plate 358. The ceramic top plate 358 has an ESC (clamp) electrode 360 ​​or electrode assembly therein. A metal layer 362 bonds the ceramic top plate 358 to the top surface of the ceramic bottom plate 352. A thermocouple 364 extends through openings in the ceramic bottom plate 352 and metal layer 362. A high-voltage insulator 366 extends through openings in the ceramic bottom plate 352 and metal layer 362 to house an ESC high-voltage connection 368.

[0039] 3B , in one embodiment, the ESC 350 includes a gas path 370 through the ceramic shaft 356, through the ceramic bottom plate 352, through the metal layer 362, and through the ceramic top plate 358. In one embodiment, the gas path 370 is for heat transfer at a location between the substrate 399 and the ceramic top plate 358. In one embodiment, the ESC 350 includes an opening 372 through the ceramic shaft 356, a groove 374 on the top surface of the ceramic bottom plate 352, an opening 376 in the metal layer 362, and an opening 378 in the ceramic top plate 358. In one embodiment, the path including the opening 372, the groove 374, and the opening 378 provides a gas path for an edge purge to block deposition on the outside of the substrate 399.

[0040] In another aspect, FIG. 4 is a schematic cross-sectional view of a processing chamber 400 including a substrate support assembly 428, according to an embodiment of the present disclosure. In the example of FIG. 4, the processing chamber 400 is a plasma-enhanced chemical vapor deposition (PECVD) chamber. As shown in FIG. 4, the processing chamber 400 includes one or more sidewalls 402, a bottom 404, a gas distribution plate 410, and a cover plate 412. The sidewalls 402, the bottom 404, and the cover plate 412 collectively define a processing volume 406. The gas distribution plate 410 and the substrate support assembly 428 are disposed within the processing volume 406. The processing volume 406 is accessed through a sealable slit valve opening 408 formed through the sidewall 402, which allows a substrate 405 to enter and exit the processing chamber 400. A vacuum pump 409 is coupled to the chamber 400 to control the pressure within the processing volume 406.

[0041] The gas distribution plate 410 is coupled around its periphery to a cover plate 412. A gas source 420 is coupled to the cover plate 412 to provide one or more gases through the cover plate 412 to a plurality of gas passages 411 formed in the cover plate 412. The gases flow through the gas passages 411 into the processing volume 406 toward the substrate receiving surface 432.

[0042] An RF power supply 422 is coupled to the cover plate 412 and / or directly to the gas distribution plate 410 via an RF power supply 424 to supply RF power to the gas distribution plate 410. Various RF frequencies can be used. For example, the frequency can be between about 0.3 MHz and about 200 MHz, such as about 13.56 MHz. An RF return path 425 couples the substrate support assembly 428 to the RF power supply 422 through the sidewall 402. The RF power supply 422 generates an electric field between the gas distribution plate 410 and the substrate support assembly 428. The electric field forms a plasma from gases present between the gas distribution plate 410 and the substrate support assembly 428. The RF return path 425 completes an electrical circuit for the RF energy, preventing stray plasma from causing RF arcing due to voltage differences between the substrate support assembly 428 and the sidewall 402. Thus, the RF return path 425 mitigates arcing, which can cause process drift, particle contamination, and damage to chamber components.

[0043] The substrate support assembly 428 includes a substrate support 430 and a stem 434. The stem 434 is coupled to a lift system 436 adapted to raise and lower the substrate support assembly 428. The substrate support 430 includes a substrate receiving surface 432 for supporting the substrate 405 during processing. Lift pins 438 are movably disposed through the substrate support 430 to move the substrate 405 toward and away from the substrate receiving surface 432 to facilitate substrate transfer. An actuator 414 is utilized to extend and retract the lift pins 438. A ring assembly 433 may be disposed around the substrate 405 during processing. The ring assembly 433 is configured to prevent or reduce unwanted deposition on surfaces of the substrate support 430 that are not covered by the substrate 405 during processing.

[0044] The substrate support 430 also includes heating and / or cooling elements 439 for maintaining the substrate support 430 and the substrate 405 disposed thereon at a desired temperature. In one embodiment, the heating and / or cooling elements 439 may be utilized to maintain the temperature of the substrate support 430 and the substrate 405 disposed thereon at less than about 800 degrees Celsius or less during processing. In one embodiment, the heating and / or cooling elements 439 may be used to control the substrate temperature to less than 650 degrees Celsius, such as between 300 degrees Celsius and about 400 degrees Celsius. In an embodiment, the substrate support 430 / substrate support assembly 428 is as described above in connection with FIGS. 1, 2A-2C, and 3.

[0045] In another aspect, FIG. 5 is a schematic partial cross-sectional view of a processing chamber 500 including a substrate support assembly 100, according to an embodiment of the present disclosure. The processing chamber 500 has a body 501. The body has a sidewall 502, a bottom 504, and a showerhead 512. The sidewall 502, the bottom 504, and the showerhead 512 define an interior volume 506. In some embodiments, a substrate support assembly 100, such as those described in connection with FIGS. 1, 2A-2C, 3A, or 3B, is disposed within the interior volume 506. An RF generator 580 may be coupled to an electrode 582 within the showerhead 512. The RF generator 580 may have an associated RF return path 588 for completing an RF circuit when a plasma is present. Advantageously, an RF ground path can be maintained to sustain the plasma, providing a long service life for the substrate support assembly 100.

[0046] In one embodiment, the semiconductor wafer or substrate supported by the substrate support assembly 100 is composed of a material suitable for withstanding the manufacturing process, upon which semiconductor processing layers can be appropriately disposed. For example, in one embodiment, the semiconductor wafer or substrate is composed of a Group IV-based material, such as, but not limited to, crystalline silicon, germanium, or silicon / germanium. In a specific embodiment, the semiconductor wafer comprises a single crystal silicon substrate. In a particular embodiment, the single crystal silicon substrate is doped with impurity atoms. In another embodiment, the semiconductor wafer or substrate is composed of a III-V material.

[0047] Embodiments of the present disclosure may be provided as a computer program product or software, which may include a machine-readable medium having instructions stored thereon, which may be used to program a computer system (or other electronic device) to perform processes according to embodiments of the present disclosure. In one embodiment, the computer system is coupled to the processing chamber 400 and substrate support assembly 428 described above in connection with FIG. 4 or the processing chamber 500 and substrate support assembly 100 described above in connection with FIG. 5. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine- (e.g., computer) readable storage medium (e.g., read-only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine- (e.g., computer) readable transmission medium (electrical, optical, acoustic, or other form of propagated signal (e.g., infrared signal, digital signal, etc.)), etc.

[0048] FIG. 6 illustrates a schematic diagram of a machine in the exemplary form of a computer system 600 upon which a set of instructions may be executed to cause the machine to perform any one or more of the methodologies described herein. In alternative embodiments, the machine may be connected (e.g., networked) to other machines in a local area network (LAN), an intranet, an extranet, or the Internet. The machine may operate in the role of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine may be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile phone, a web appliance, a server, a network router, switch, or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be performed by the machine. Furthermore, although only a single machine is shown, the term "machine" should be interpreted to include a collection of machines (e.g., computers) that individually or jointly execute a set of instructions (one or more) to perform any one or more of the methodologies described herein.

[0049] The exemplary computer system 600 includes a processor 602, a main memory 604 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), or Rambus DRAM (RDRAM)), a static memory 606 (e.g., flash memory, static random access memory (SRAM)), and a secondary memory 618 (e.g., data storage device), which communicate with each other via a bus 630.

[0050] Processor 602 represents one or more general-purpose processing devices, such as, for example, a microprocessor, a central processing unit, etc. More specifically, processor 602 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor that executes other instruction sets, or a processor that executes a combination of instruction sets. Processor 602 may also be one or more special-purpose processing devices, such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a network processor, etc. Processor 602 is configured to execute processing logic 626 for performing the operations described herein.

[0051] Computer system 600 may further include a network interface device 608. Computer system 600 may also include a video display unit 610 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 612 (e.g., a keyboard), a cursor control device 614 (e.g., a mouse), and a signal generation device 616 (e.g., a speaker).

[0052] Secondary memory 618 may include a machine-accessible storage medium (or, more specifically, a computer-readable storage medium) 632 having stored thereon one or more sets of instructions (e.g., software 622) that embody any one or more of the methods or functions described herein. The software 622 may reside, completely or at least partially, within main memory 604 and / or within processor 602 while it is being executed by computer system 600, with main memory 604 and processor 602 also constituting machine-readable storage media. The software 622 may further be transmitted or received over network 620 via network interface device 608.

[0053] Although in the exemplary embodiment, machine-accessible storage medium 632 is shown as being a single medium, the term "machine-readable storage medium" should be interpreted to include a single medium or multiple media (e.g., centralized or distributed databases and / or associated caches and servers) that store one or more sets of instructions. The term "machine-readable storage medium" should be interpreted to include any medium that is capable of storing or encoding a set of instructions that are executed by a machine and that cause the machine to perform any one or more of the methods of the present disclosure. Thus, the term "machine-readable storage medium" should be interpreted to include, but is not limited to, solid-state memory, and optical and magnetic media.

[0054] Thus, an electrostatic chuck (ESC) for a plasma processing chamber and a method for manufacturing the ESC are disclosed.

Claims

1. 1. A method of manufacturing a substrate support assembly, comprising: forming a ceramic bottom plate having a heater element therein; forming a ceramic top plate having an electrode therein; and Bonding the ceramic top plate to the ceramic bottom plate with a metal layer between the ceramic top plate and the ceramic bottom plate, wherein the ceramic top plate is in direct contact with the metal layer and the metal layer is in direct contact with the ceramic bottom plate. Including, joining the ceramic top plate to the ceramic bottom plate with the metal layer comprises heating the ceramic bottom plate, the metal layer, and the ceramic top plate to a temperature less than 600 degrees Celsius; The method wherein the metal layer is aluminum foil.

2. The method of claim 1, wherein the method includes cleaning the surface of the aluminum foil to remove a passivation layer on the aluminum foil before joining the ceramic top plate to the ceramic bottom plate with the metal layer.

3. bonding a ceramic shaft to the ceramic bottom plate on a side of the ceramic bottom plate opposite the metal layer before bonding the ceramic top plate to the ceramic bottom plate with the metal layer. The method of claim 1 further comprising:

4. 4. The method of claim 3, wherein bonding the ceramic shaft to the ceramic bottom plate comprises heating the ceramic shaft and the ceramic bottom plate to a temperature greater than 1400 degrees Celsius to form a diffusion bond between the ceramic shaft and the ceramic bottom plate.

5. 4. The method of claim 3, wherein bonding the ceramic shaft to the ceramic bottom plate comprises connecting the ceramic shaft to the ceramic bottom plate by a second metal layer, the ceramic bottom plate being in direct contact with the second metal layer and the second metal layer being in direct contact with the ceramic shaft.

6. The method of claim 1, wherein the metal layer has a thickness in the range of 50 to 500 microns.

7. The method of claim 1, wherein the aluminum foil is impregnated with 2% to 20% Si as an atomic percentage of the total foil composition.

8. The method described in claim 1, wherein the aluminum foil is planar.

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