Mixed metal base plate for improved thermal expansion matching with thermal oxide spray coat

Abstract

A base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber includes a first component made of a first material including a metal and a non-metal. The first material has a first coefficient of thermal expansion. A layer coating the first component is made of a second material. The second material has a second coefficient of thermal expansion. The first and second coefficients of thermal expansion are different.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 62 / 960,417, filed January 13, 2020. The entire disclosures of the above-referenced applications are incorporated herein by reference.

[0002] The present disclosure relates generally to substrate processing systems, and more particularly to using a mixed metal base plate in a processing chamber to improve thermal expansion matching with a spray coat applied on the base plate. [Background technology]

[0003] The background description provided herein is intended to present the contents of the present disclosure generally. Work by the presently named inventors within the scope of what is described in this Background section, as well as aspects of the description that may not otherwise be considered prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure.

[0004] A substrate processing system typically includes multiple processing chambers (also called process modules) that perform deposition, etching, and other processing on substrates, such as semiconductor wafers. Examples of processes that can be performed on a substrate include, but are not limited to, plasma-enhanced chemical vapor deposition (PECVD) processes, chemically enhanced plasma vapor deposition (CEPVD) processes, and sputtering physical vapor deposition (PVD) processes. Additional examples of processes that can be performed on a substrate include, but are not limited to, etching (e.g., chemical etching, plasma etching, reactive ion etching, etc.) and cleaning processes.

[0005] During processing, a substrate is placed on a substrate support, such as a pedestal or electrostatic chuck (ESC), in a processing chamber of a substrate processing system. During deposition, a gas mixture containing one or more precursors is introduced into the processing chamber and a plasma is struck to activate a chemical reaction. During etching, a gas mixture containing an etching gas is introduced into the processing chamber and a plasma is struck to activate a chemical reaction. A computer-controlled robot typically transfers substrates from one processing chamber to another in the order in which the substrates are processed. Summary of the Invention

[0006] A base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber includes a first component made of a first material including a metal and a non-metal. The first material has a first coefficient of thermal expansion. A layer coating the first component is made of a second material. The second material has a second coefficient of thermal expansion. The first and second coefficients of thermal expansion are different.

[0007] In another feature, the first and second coefficients of thermal expansion are within a predetermined range.

[0008] In another feature, the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion.

[0009] In another feature, the first coefficient of thermal expansion is less than the coefficient of thermal expansion of the metal.

[0010] In other features, the predetermined range is between a first value and a second value, the second value being greater than the first value, the first coefficient of thermal expansion being closer to the second value than the first value, and the second coefficient of thermal expansion being closer to the first value than the second value.

[0011] In another feature, the predetermined range is 6-12.

[0012] In another feature, the layer of the second material has a thickness of 30 μm to 2 mm.

[0013] In other features, the first coefficient of thermal expansion is about 11. The second coefficient of thermal expansion is about 8.

[0014] In another feature, the metal is aluminum and the non-metal is silicon carbide.

[0015] In another feature, the second material is a ceramic material.

[0016] In another feature, the second material is alumina or yttria.

[0017] In other features, the base plate further comprises a second layer made of a third material disposed on the layer coating the first component, and a third component made of the second material disposed on the second layer.

[0018] In another feature, the second layer joins the third component to the first component.

[0019] In other features, the second layer conducts heat between the third component and the first component and absorbs shear stresses in a predetermined temperature range for a predetermined period of time.

[0020] In yet another feature, a method for fabricating a base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber includes fabricating a first component of the base plate using a first material including a metal and a non-metal. The first material has a first coefficient of thermal expansion. The method includes coating the first component of the base plate with a layer of a second material having a second coefficient of thermal expansion. The first and second coefficients of thermal expansion are different.

[0021] In another feature, the first and second coefficients of thermal expansion are within a predetermined range.

[0022] In another feature, the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion.

[0023] In another feature, the first coefficient of thermal expansion is less than the coefficient of thermal expansion of the metal.

[0024] In other features, the predetermined range is between a first value and a second value, the second value being greater than the first value, the first coefficient of thermal expansion being closer to the second value than the first value, and the second coefficient of thermal expansion being closer to the first value than the second value.

[0025] In another feature, the predetermined range is 6-12.

[0026] In another feature, the layer of the second material has a thickness of 30 μm to 2 mm.

[0027] In other features, the first coefficient of thermal expansion is about 11. The second coefficient of thermal expansion is about 8.

[0028] In another feature, the method further includes selecting aluminum as the metal and selecting silicon carbide as the non-metal.

[0029] In another feature, the method further includes selecting a ceramic material as the second material.

[0030] In another feature, the method further includes selecting alumina or yttria as the second material.

[0031] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief explanation of the drawings]

[0032] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0033] [Figure 1] FIG. 1 is a diagram showing a first example of a substrate processing system including a processing chamber.

[0034] [Figure 2] FIG. 2 is a diagram showing a second example of a substrate processing system including a processing chamber.

[0035] [Figure 3] FIG. 3 is a diagram illustrating a third example of a substrate processing system including a processing chamber.

[0036] [Figure 4] FIG. 4 is a schematic diagram of an example base plate according to the present disclosure that may be used in a processing chamber of a substrate processing system. [Figure 5] FIG. 5 is a schematic diagram of an example base plate according to the present disclosure that may be used in a processing chamber of a substrate processing system.

[0037] [Figure 6] FIG. 6 illustrates a method of manufacturing the base plate shown in FIGS. 4 and 5 for a substrate support assembly of a substrate processing system according to the present disclosure.

[0038] [Figure 7] FIG. 7 illustrates a method for manufacturing the substrate of the base plate shown in FIGS. 4 and 5 according to the present disclosure.

[0039] In the drawings, reference numbers may be reused to refer to similar and / or identical elements. DETAILED DESCRIPTION OF THE INVENTION

[0040] The base plate is a basic component of the processing chamber on which the wafer is placed during processing. The base plate is typically made of a metal substrate with a spray coat of oxide material covering the outside of the metal substrate. The spray coat is used to protect the base plate (i.e., the metal substrate) from the extreme environment of the processing chamber (e.g., to protect the base plate from plasma erosion and arcing).

[0041] Depending on the process, the base plate can be utilized over a wide temperature range, for example, greater than about 100 degrees Celsius. Managing stresses on the spray coat throughout the entire operating regime to ensure adequate adhesion of the spray coat to the metal substrate and to ensure reduced cracking of the spray coat can be difficult due to the mismatch in thermal expansion of the metal substrate compared to the spray coat. According to the present disclosure, by utilizing a mixed metal substrate whose thermal expansion is better matched to the spray coat, stresses on the spray coat can be relatively relaxed throughout the full operating range.

[0042] The base plate is typically made of aluminum with a spray-coated aluminum oxide coating. The thermal expansion coefficient of aluminum is greater than 20 μm / °C / m. This is significantly greater than the thermal expansion coefficient of aluminum oxide, which is approximately 8 μm / °C / m. When the oxide layer is applied at high temperatures, the coating experiences significant tensile stress at cryogenic temperatures, causing the aluminum substrate to shrink much more than the oxide spray-coat.

[0043] The present disclosure provides a base plate including a mixed metal substrate that better matches the thermal expansion properties of the underlying substrate to the thermal expansion properties of the spray coat applied thereon. Specifically, according to the present disclosure, the aluminum metal substrate in the base plate is replaced with a mixed metal substrate having a thermal expansion coefficient that better matches that of the spray coat (e.g., an aluminum oxide layer). For example, a material called a metal matrix composite (discussed below) is used as the base plate substrate onto which the ceramic material is spray coated. By better matching the thermal expansion coefficients between the mixed metal substrate and the spray coat, stress on the spray coat can be maintained near a zero-stress condition over most or all operating temperatures. This alleviates the need to modify the dimensional design of the base plate to minimize stress on the spray coat.

[0044] The teachings of the present disclosure are not limited to base plates. Rather, they can be extended and applied to various other components of processing chambers that typically include a metal substrate covered with a spray-coated oxide layer and are subject to stresses due to the extreme environment of the processing chamber. These components can also be fabricated using mixed-metal substrates coated with a ceramic layer, thereby improving thermal expansion matching between the substrate and the ceramic layer and reducing stress on these components. Non-limiting examples of such components include the interior walls of processing chambers, various annular ring-shaped components used in processing chambers, showerheads, etc.

[0045] This disclosure is organized as follows: First, examples of different processing chambers are shown and described with reference to FIGS. 1-3 to understand the harsh environment within the processing chamber and the various components to which the teachings of the present disclosure can be applied. Next, metal matrix composite (MMC) materials are described in detail. After that, an exemplary design of a base plate according to the present disclosure is shown and described with reference to FIGS. 4-5. Next, an exemplary method of manufacturing a base plate according to the present disclosure is shown and described with reference to FIGS. 6-7.

[0046] FIG. 1 illustrates an example of a substrate processing system 100 including a processing chamber 102. While the example is described in the context of plasma-enhanced chemical vapor deposition (PECVD), the teachings of the present disclosure may be applied to other types of substrate processing, such as atomic layer deposition (ALD), plasma-enhanced ALD (PEALD), CVD, or other processes, including etch processes. The system 100 includes a processing chamber 102 that surrounds the other components of the system 100 and contains an RF plasma (if used). The processing chamber 102 includes an upper electrode 104 and an electrostatic chuck (ESC) 106 or other substrate support. During operation, a substrate 108 is positioned on the ESC 106.

[0047] For example, the upper electrode 104 can include a gas distribution device 110, such as a showerhead, for introducing and distributing process gases. The gas distribution device 110 can include a stem portion including one end connected to the top surface of the processing chamber 102. The base portion of the showerhead is generally cylindrical and extends radially outward from the opposite end of the stem portion at a location spaced from the top surface of the processing chamber 102. The surface or faceplate of the showerhead base portion that faces the substrate includes a plurality of holes through which vaporized precursors, process gases, or purge gases flow. Alternatively, the upper electrode 104 can include a conductive plate, and the process gases can be introduced in another manner.

[0048] The ESC 106 includes a base plate 112 that acts as a bottom electrode. The base plate 112 may include one or more channels 118 for flowing coolant through the base plate 112. The base plate 112 supports a ceramic plate 114 on which the substrate 108 is placed during processing. A bonding layer 116 is disposed between the base plate 112 and the ceramic plate 114. In some applications, the ceramic plate 114 may include one or more heaters (e.g., a multi-zone heater (not shown)).

[0049] When a plasma is used, the RF generation system 120 generates and outputs an RF voltage to one of the upper electrode 104 and the lower electrode (e.g., the base plate 112 of the ESC 106). The other of the upper electrode 104 and the base plate 112 can be DC grounded, AC grounded, or floating. By way of example only, the RF generation system 120 may include an RF generator 122 that generates RF power supplied to the upper electrode 104 or the base plate 112 by a matching and distribution network 124. In other examples, the plasma may be generated inductively or remotely.

[0050] Gas delivery system 130 includes one or more gas sources 132-1, 132-2, ..., and 132-N (collectively gas sources 132), where N is an integer greater than zero. Gas sources 132 are connected to manifold 140 by valves 134-1, 134-2, ..., and 134-N (collectively valves 134) and mass flow controllers 136-1, 136-2, ..., and 136-N (collectively mass flow controllers 136). Vapor delivery system 142 supplies vaporized precursors to manifold 140 or to a separate manifold (not shown) connected to processing chamber 102. The output of manifold 140 is supplied to processing chamber 102.

[0051] A temperature controller 150 can be in communication with the coolant assembly 154 and control the flow of coolant through the channels 118. For example, the coolant assembly 154 can include a coolant pump, a reservoir, and one or more temperature sensors (not shown). The temperature controller 150 operates the coolant assembly 154 to selectively flow coolant through the channels 118 to cool the ESC 106. In some applications, if the ceramic plate 114 includes a heater 152, the temperature controller 150 can be connected to multiple thermal control elements (TCEs) 152 disposed on the ceramic plate 114. The temperature controller 150 can be used to control the multiple TCEs 152 to control the temperature of the ESC 106 and the substrate 108. A valve 156 and a pump 158 can be used to evacuate reactants from the processing chamber 102. A system controller 160 controls the components of the system 100.

[0052] 2 illustrates another example of a substrate processing system 200. The substrate processing system 200 includes a coil driver circuit 211. In some examples, the coil driver circuit 211 includes an RF source 212, a pulse circuit 214, and an adjustment circuit (i.e., matching circuit) 213. The pulse circuit 214 controls the transformer-coupled plasma (TCP) envelope of the RF signal generated by the RF source 212 and varies the duty cycle of the TCP envelope between 1% and 99% during operation. As can be appreciated, the pulse circuit 214 and the RF source 212 can be combined or separate in some embodiments.

[0053] The conditioning circuitry 213 may be directly connected to the induction coil 216. While the substrate processing system 210 uses a single coil, some substrate processing systems may use multiple coils (e.g., inner and outer coils). The conditioning circuitry 213 adjusts the output of the RF source 212 to a desired frequency and / or a desired phase to match the impedance of the coil 216.

[0054] The dielectric window 224 is disposed along the top side of the processing chamber 228. The processing chamber 228 includes a substrate support (or pedestal) 232 that supports a substrate 234. The substrate support 232 may include an electrostatic chuck (ESC), a mechanical chuck, or other types of chucks. Process gases are supplied to the processing chamber 228, and a plasma 240 is generated inside the processing chamber 228. The plasma 240 etches the exposed surface of the substrate 234. An RF source 250, a pulse circuit 251, and a bias matching circuit 252 can be used to bias the substrate support 232 and control ion energy during operation.

[0055] A gas delivery system 256 can be used to supply a process gas mixture to the processing chamber 228. The gas delivery system 256 can include process and inert gas sources 257, a gas metering system 258, such as valves and mass flow controllers, and a manifold 259. A gas injector 263 can be positioned at the center of the dielectric window 224 and is used to inject the gas mixture from the gas delivery system 256 into the processing chamber 228. Additionally or alternatively, the gas mixture can be injected from the side of the processing chamber 228.

[0056] A heater / cooler 264 can be used to heat / cool the substrate support 232 to a predetermined temperature. An exhaust system 265 includes a valve 266 and a pump 267 for controlling the pressure within the processing chamber and / or for removing reactants from the processing chamber 228 by purging or evacuation.

[0057] A controller 254 can be used to control the etching process. The controller 254 monitors system parameters and controls the delivery of gas mixtures, striking, maintaining, and extinguishing the plasma, removing reactants, supplying cooling gases, etc. Additionally, as described below, the controller 254 can control various aspects of the coil driver circuit 210, the RF source 250, and the bias matching circuit 252, etc.

[0058] 3 shows a processing chamber 300 for etching a layer of a substrate. The processing chamber 300 includes a lower chamber region 302 and an upper chamber region 304. The lower chamber region 302 is defined by a chamber sidewall surface 308, a chamber bottom surface 310, and the lower surface of a gas distribution device 314. The upper chamber region 304 is defined by the upper surface of the gas distribution device 314 and the inner surface of a dome 318.

[0059] In some examples, the dome 318 rests on a first annular support 321. In some examples, the first annular support 321 includes one or more spaced holes 323 for delivering process gas to the upper chamber region 304. In some examples, the process gas is delivered upward by the one or more spaced holes 323 at an acute angle relative to a plane containing the gas distribution device 314, although other angles / directions can be used. In some examples, a gas flow channel 334 in the first annular support 321 delivers gas to the one or more spaced holes 323.

[0060] The first annular support 321 can rest on a second annular support 325 that defines one or more spaced holes 327 for delivering process gases from gas flow channels 329 to the lower chamber region 302. In some examples, holes 331 in the gas distribution device 314 are aligned with the holes 327. In other examples, the gas distribution device 314 has a smaller diameter, and holes 331 are not required. In some examples, the process gases are delivered downward toward the substrate 326 by the one or more spaced holes 327 at an acute angle relative to a plane containing the gas distribution device 314, although other angles / directions can be used. In other examples, the upper chamber region 304 is cylindrical with a flat top surface, and one or more flat induction coils can be used. In some examples, a single chamber can be used with a spacer positioned between the showerhead and the substrate support.

[0061] A substrate support 322 is disposed in the lower chamber region 304. In some examples, the substrate support 322 includes an electrostatic chuck (ESC), although other types of substrate supports can be used. A substrate 326 is disposed on an upper surface of the substrate support 322 during etching. In some examples, the temperature of the substrate 326 can be controlled by a heater plate 330, an optional cooling plate with fluid channels, and one or more sensors (not shown), although any other suitable substrate support temperature control system can be used.

[0062] In some examples, the gas distribution device 314 includes a showerhead (e.g., a plate 328 having a plurality of spaced holes 327). The plurality of spaced holes 327 extend from an upper surface of the plate 328 to a lower surface of the plate 328. In some examples, the spaced holes 327 have a diameter ranging from 0.4 inches to 0.75 inches, and the showerhead is made of a conductive material such as aluminum or a non-conductive material such as ceramic with embedded electrodes made of a conductive material.

[0063] One or more induction coils 340 are disposed around an outer portion of the dome 318. When energized, the one or more induction coils 340 generate an electromagnetic field inside the dome 318. In some examples, an upper coil and a lower coil are used. A gas injector 342 injects one or more gas mixtures from a gas delivery system 350-1. In some examples, the gas delivery system 350-1 includes one or more gas sources 352, one or more valves 354, one or more mass flow controllers (MFCs) 356, and a mixing manifold. 3 58, although other types of gas delivery systems may be used. A gas splitter (not shown) may be used to vary the flow rate of the gas mixture. Another gas delivery system 350-2 may be used to supply an etching gas or etching gas mixture to gas flow channels 329 and / or 334 (in addition to or instead of the etching gas from gas injector 342).

[0064] In some examples, the gas injector 342 includes a central injection location that directs gas downward and one or more side injection locations that inject gas at an angle relative to the downward direction. In some examples, the gas delivery system 350-1 delivers a first portion of the gas mixture at a first flow rate to the central injection location of the gas injector 342 and a second portion of the gas mixture at a second flow rate to the side injection locations of the gas injector 342. In other examples, different gas mixtures are delivered by the gas injector 342. In some examples, the gas delivery system 350-1 delivers a regulated gas to the gas flow channels 329 and 334 and / or to other locations within the processing chamber, as described below.

[0065] A plasma generator 370 can be used to generate RF power that is output to the one or more inductive coils 340. A plasma 390 is generated in the upper chamber region 304. In some examples, the plasma generator 370 includes an RF generator 372 and a matching network 374. The matching network 374 matches the impedance of the RF generator 372 to the impedance of the one or more inductive coils 340. In some examples, the gas distribution device 314 is connected to a reference potential, such as ground. A valve 378 and a pump 380 can be used to control the pressure in the lower and upper chamber regions 302, 304 and to evacuate the coolant.

[0066] A controller 376 communicates with gas delivery systems 350-1 and 350-2, valves 378, pumps 380, and plasma generator 370 to control the flow of process gases, purge gases, RF plasma, and chamber pressure. In some examples, the plasma is maintained inside dome 318 by one or more inductive coils 340. One or more gas mixtures are introduced from the top of the chamber using gas injectors 342 (and / or holes 323), and the plasma is confined within dome 318 using gas distribution device 314.

[0067] Confining the plasma within the dome 318 allows for volumetric recombination of plasma species, which can then release the desired etchant species through the gas distribution device 314. In some instances, no RF bias is applied to the substrate 326. As a result, there is no active sheath above the substrate 326, and ions do not strike the substrate with finite energy. Some ions diffuse from the plasma region through the gas distribution device 314. However, the amount of diffusing plasma is an order of magnitude less than that located inside the dome 318. Most ions in the plasma are lost due to volumetric recombination at high pressures. Surface recombination losses at the top surface of the gas distribution device 314 also reduce the ion density below the gas distribution device 314.

[0068] In another example, an RF bias generator 384 is provided and includes an RF generator 386 and a matching network 388. The RF bias can be used to generate a plasma between the gas distribution device 314 and the substrate support or to generate a self-bias on the substrate 326 to attract ions. A controller 376 can be used to control the RF bias.

[0069] Here, we will discuss metal matrix composite (MMC) materials in detail. A metal matrix composite (MMC) is a composite material with at least two components, one of which is a metal and the other of which can be a different metal or another material such as a ceramic or organic compound. When at least three materials are used, the MMC is called a hybrid composite.

[0070] MMCs are made by dispersing reinforcing materials in a metal matrix. The reinforcing surfaces can be coated to prevent chemical reactions with the matrix. For example, carbon fibers can be used in an aluminum matrix to create a composite with low density and high strength. However, carbon reacts with the aluminum, forming brittle, water-soluble compounds on the fiber surface. To prevent this reaction, carbon fibers are coated with nickel or titanium boride.

[0071] The matrix is ​​a monolithic material with the reinforcing material embedded in it and is continuous (i.e., a pathway exists through the matrix to any point in the material, as opposed to two materials sandwiched together). In structural applications, the matrix is ​​usually a lightweight metal such as aluminum, magnesium, or titanium, which provides support for the reinforcement. For high-temperature applications, cobalt and cobalt-nickel alloy matrices can be used.

[0072] Reinforcements do not always serve a purely structural task (e.g., strengthening a compound) but are also used to modify physical properties such as wear resistance, coefficient of friction, and thermal conductivity. Reinforcements can be continuous or discontinuous. Discontinuous MMCs can be isotropic and can be processed using standard metalworking techniques such as extrusion, forging, or rolling. Additionally, they can be machined using conventional techniques, but may require additional tooling using techniques such as polycrystalline diamond (PCD) tooling.

[0073] Continuous reinforcement uses monofilament wires or fibers, such as carbon fiber or silicon carbide. The fibers are embedded in a matrix in a specific direction, resulting in an anisotropic structure, where the alignment of the material affects its strength. Discontinuous reinforcement uses short fibers or particles. Examples of such reinforcing materials include alumina and silicon carbide.

[0074] MMC fabrication can generally be of three types: solid, liquid, and vapor. MMCs are fabricated at high temperatures to allow diffusion bonding of the fiber / matrix interface. Subsequently, when they are cooled to ambient temperature, residual stresses are created in the composite due to the mismatch between the moduli of the metal matrix and the fibers. Residual stresses during fabrication have a significant impact on the mechanical behavior of MMCs under all loading conditions. In some cases, thermal residual stresses are high enough to initiate plastic deformation within the matrix during the fabrication process.

[0075] Solid-state manufacturing methods include powder blending and consolidation (powder metallurgy), in which powder metal and discontinuous reinforcement are mixed and bonded through a process of compaction, degassing, and thermomechanical processing, sometimes via hot isostatic pressing (HIP) or extrusion. Other solid-state manufacturing methods include foil diffusion bonding, in which layers of metal foil are sandwiched between long fibers and then pressed to form a matrix.

[0076] Liquid-state manufacturing methods include electroplating and electroforming, in which a solution containing metal ions loaded with reinforcing particles is co-deposited to form a composite material. Other liquid-state manufacturing methods include stir casting, in which discontinuous reinforcement can be stirred into molten metal and allowed to solidify. Pressure infiltration, for example, uses gas pressure to infiltrate the molten metal into the reinforcement. Squeeze casting involves injecting molten metal into a mold with fibers pre-placed inside. Spray deposition involves spraying molten metal onto a continuous fiber substrate. Reactive processing involves a chemical reaction between one reactant forming the matrix and another reactant forming the reinforcement.

[0077] Yet other methods include semi-solid powder processing, in which a powder mixture is heated to a semi-solid state and pressure is applied to form a composite. In physical vapor deposition, the coating is applied by passing fibers through a thick cloud of vaporized metal. In in-situ fabrication, the coating is applied by passing fibers through a thick cloud of vaporized metal.

[0078] MMCs are more expensive than the conventional materials they replace. As a result, they are used where the improved properties and performance justify the additional cost. Examples of these applications include aircraft components, space systems, and high-end or luxury sports equipment.

[0079] Compared to traditional polymer matrix composites, MMCs are fire resistant, can operate over a wider temperature range, do not absorb moisture, have better electrical and thermal conductivity, are resistant to radiation damage, and do not exhibit outgassing. However, MMCs tend to be more expensive, and fiber-reinforced materials can be difficult to fabricate, so there is limited experience available in their use.

[0080] 4 and 5 schematically illustrate an example of a base plate 400 according to the present disclosure. Elements of the base plate 400, such as cooling channels, heaters, and electrodes, have been omitted to highlight details regarding the composition of the base plate 400. In FIG. 4, the base plate 400 comprises a mixed metal substrate 402 (shown in detail in FIG. 5) covered with a ceramic coating 404. For example, the substrate 402 may comprise an MMC material made from a metal, such as aluminum, and a reinforcing material, such as silicon carbide. For example, the ceramic coating 404 may comprise aluminum oxide (e.g., alumina or Al2O3) spray-coated onto the substrate 402.

[0081] FIG. 5 shows example compositions of substrate 402. For example, substrate 402 can include different densities of reinforcing material in a metal. For example, the density of reinforcing material 410, such as silicon carbide, combined with metal 412, such as aluminum, can vary, as shown in the three examples from left to right. As the density of reinforcing material 410 increases in the examples shown from left to right, the coefficient of thermal expansion (CTE) of the composite material (i.e., metal 412 and reinforcing material 410) of substrate 402 decreases. For example, if metal 412 is aluminum and reinforcing material 410 is silicon carbide, the CTE of the composite material shown in the left, center, and right boxes can be 14, 12, and 11, respectively. Thus, in the examples shown, it can be said that the CTE of the composite material decreases inversely with the density of reinforcing material 410 in metal 412.

[0082] Notably, in the illustrated example, the CTE of the composite material is significantly less than that of aluminum, which is approximately 22, and closer to that of alumina, which is approximately 8. Preferably, a composite material having a CTE in the range of 6 to 12 can be used as the substrate 402 for the base plate 400, with a layer of alumina spray-coated thereon. Thus, for example, the composite material shown in the right box of FIG. 5 , in which the density of reinforcing material (e.g., silicon carbide) 410 in metal (e.g., aluminum) 412 results in a composite material having a CTE of approximately 11, which is suitable for forming the substrate 402 of the base plate 400. The substrate 402 thus formed can then be spray-coated with a layer of alumina having a CTE of approximately 8. This combination of using a substrate 402 comprised of a composite material formed of aluminum and silicon carbide having a CTE of approximately 11 and using a spray coat of alumina having a CTE of approximately 8 minimizes stress on the base plate 400 within the processing chamber. As a result, the combination of aluminum and silicon carbide spray coated with alumina prevents cracking of the layer of alumina (i.e., ceramic material 404) coated on substrate 402 due to a better match of the CTE of substrate 402 (e.g., aluminum and silicon carbide) and ceramic material 404 (e.g., alumina).

[0083] 6 illustrates a method 450 for fabricating a base plate (e.g., the base plate 400 shown in FIGS. 4 and 5) for a substrate support assembly according to the present disclosure. At 452, the method 450 includes fabricating the base plate using a first material (e.g., the substrate 402 of the base plate 400 shown in FIGS. 4 and 5) having a first CTE. At 454, the method 450 includes coating the first material (e.g., the substrate 402 of the base plate 400 shown in FIGS. 4 and 5) with a second material (e.g., the ceramic coating 404 of the base plate 400 shown in FIGS. 4 and 5) having a second CTE, wherein the first and second CTEs are within a predetermined range.

[0084] For example, the predetermined range (e.g., 6 to 12) has a first value (e.g., 6) and a second value (e.g., 12) greater than the first value. The first CTE has a value (e.g., 11) within the predetermined range (e.g., 6 to 12). The second CTE has a value (e.g., 8) within the predetermined range (e.g., 6 to 12). For example, the second CTE is less than the first CTE. For example, the first CTE (e.g., 11) is closer to the second value (e.g., 12) within the predetermined range (e.g., 6 to 12) than the first value (e.g., 8) within the predetermined range (e.g., 6 to 12). For example, the second CTE (e.g., 8) is closer to the first value (e.g., 6) within the predetermined range (e.g., 6 to 12) than the second value (e.g., 12) within the predetermined range (e.g., 6 to 12). 45 6 4, the method 450 includes using a coated base plate (eg, the base plate 400 shown in FIGS. 4 and 5) in a processing chamber.

[0085] Of course, any other material having a CTE in the range of 6 to 12 can be used to fabricate the base plate. That is, any material having a CTE in the range of 6 to 12 can be used as the coating material for the substrate and base plate. Furthermore, in some embodiments, the second CTE of the coating material can be greater than the first CTE of the substrate material, so long as the CTE is in the range of 6 to 12.

[0086] FIG. 7 illustrates a method 480 for manufacturing a substrate for a base plate (e.g., substrate 402 of base plate 400 shown in FIGS. 4 and 5 , which is the first material described in FIG. 6 ) according to the present disclosure. At 482, method 480 includes selecting a metal for manufacturing the substrate (i.e., the first material). For example, method 480 includes selecting element 412 shown in FIG. 5 . For example, method 480 includes selecting aluminum as element 412 shown in FIG. 5 . At 484, method 480 includes adding a reinforcing material (e.g., element 410 shown in FIG. 5 ) to the metal. For example, method 480 includes selecting silicon carbide as element 410 shown in FIG. 5 . At 486, method 480 includes manufacturing the substrate for the base plate using the metal and the reinforcing material.

[0087] For example, it should be noted that fabricating a base plate comprising a combination of aluminum and silicon carbide and having an alumina coating is not simply the result of design choice or routine experimentation. Rather, it is the result of thorough and extensive research into various materials, their properties, and their behavior in various combinations and under widely differing thermal, chemical, and electrical operating conditions encountered in different substrate processing systems. The present disclosure fulfills a long-felt need in the industry for a method to minimize stress on the coating on the base plate and prevent cracking of the coating. By maintaining the CTE of both the substrate and the base plate coating within a narrow range as described above, the present disclosure provides the unexpected result of minimizing stress on the coating on the base plate and preventing cracking of the coating.

[0088] The base plate of the MMC material can be manufactured using a variety of processes including casting, machining, 3D printing, etc. Additionally, in some examples, the coating material on the MMC material can also include other materials such as, for example, yttria (i.e., yttrium oxide or YO) that can be used in manufacturing some of the components of the processing chamber.

[0089] One advantage of using an MMC material for the base plate is that a thicker spray coat can be sprayed onto the base plate than if the base plate were made of a metal such as aluminum. For example, the thickness of the coating material can be about 30 μm to about 2 mm. The limit to the thickness of the spray coat on an aluminum base plate is the stress that builds up in the coating film (which can induce cracking of the spray coat). The stress is related to (among other factors) the lattice mismatch and adhesion properties between the substrate (metal) and the coating film. By changing the base plate substrate from metal to MMC, the stress on the coating can be reduced, allowing for a thicker film.

[0090] Thicker film coatings can have multiple applications. For example, a thicker film can simply be used for a higher voltage standoff, allowing for a larger RF voltage to the ESC. Furthermore, if the process performed in the processing chamber involves slightly etching away some amount of film during plasma processing, a thicker film can extend the life of the base plate. Furthermore, if a portion of the film needs to be removed to clean the ESC, a thicker film can extend the life of the ESC. Thinner spray coats may also be desirable for some properties, such as reducing the temperature drop across the coat (i.e., allowing for cooler wafers) and for better capacitance matching to improve RF performance. Other advantages are also contemplated.

[0091] An additional benefit of using an MMC material for the base plate is that the improved CTE match between the base plate and the ceramic plate can aid in debonding of the bonding layer disposed between the base plate and the ceramic plate and can also prevent cracking of the ceramic plate. For example, in FIG. 1 , bonding layer 116 disposed between base plate 112 and ceramic plate 114 serves multiple purposes, including physically bonding base plate 112 and ceramic plate 114, improving thermal conduction between base plate 112 and ceramic plate 114, and maintaining sufficient elasticity to withstand shear stresses over a wide temperature range (resulting from thermal expansion and contraction of base plate 112 and ceramic plate 114 caused by temperature changes during substrate processing).

[0092] To achieve these objectives, selecting the composition and thickness of a material for the bonding layer 116 can be difficult when the CTEs of the base plate 112 and the ceramic plate 114 differ significantly. Specifically, the thermal and elastic requirements described above impose strict constraints on the selection of a material for the bonding layer 116, increasing the cost of the ESC. For example, the material for the bonding layer 116 must not only transport heat between the base plate 112 and the ceramic plate 114, but also maintain elasticity over a wide temperature range to absorb shear stresses caused by thermal expansion and contraction of the base plate 112 and the ceramic plate 114. Failures in the bonding layer 116, such as glass transitions (i.e., when the material changes from a hard glassy material to a soft material), can still occur despite adherence to strict constraints, which can cause downtime and further increase costs.

[0093] The use of an MMC material for the base plate 112 having a CTE that closely matches the CTE of the ceramic plate 114 significantly alleviates the above-mentioned constraints on the material used for the bonding layer 116. The base plate 112 can be similar to the base plate 400 shown in FIGS. 4 and 5 and can be coated with a ceramic coating 404 as shown in FIGS. 4 and 5. Furthermore, the ceramic coating 404 and the ceramic plate 114 can comprise the same material. Thus, the CTE of the base plate 112 can be adjusted by adjusting the CTE of the ceramic coating on the base plate 400. Gu4 Ceramic is as consistent with the CTE of 04 as it is with The CTE of the backplate 114 is matched.

[0094] Due to the CTE matching between the base plate 112 and the ceramic plate 114, the material for the bonding layer 116 can be selected from a wide variety of materials with varying thermal and mechanical properties. The thickness of the bonding layer 116 can be relaxed. Bonding between the base plate 112 and the ceramic plate 114 with an unfavorable glass transition of the bonding layer 116 can still be applicable (i.e., not necessarily cause delamination) due to the improved CTE matching. The bonding layer 116 does not delaminate over a relatively wide temperature range. The bonding layer 116 absorbs shear stress over a relatively wide temperature range for a relatively long period of time (e.g., the lifetime of the ESC). Using an MMC material for the base plate 112 with a CTE that closely matches that of the ceramic plate 114 can also reduce the risk of cracking of the ceramic plate 114. As a result, the cost of the ESC is reduced and the lifetime and reliability of the ESC are improved.

[0095] The foregoing description is merely exemplary in nature and is not intended to limit the disclosure, its application, or uses in any way. The broad teachings of the present disclosure can be embodied in a variety of forms. Accordingly, while the present disclosure includes specific examples, the true scope of the disclosure should not be limited to such examples, as other modifications will become apparent upon review of the drawings, the specification, and the following claims. It should be understood that one or more steps in a method may be performed in a different order (or simultaneously) without altering the principles of the disclosure. Furthermore, although each embodiment is described above as having specific features, any one or more of these features described with respect to any embodiment of the present disclosure may be implemented in other embodiments and / or combined with any features of the other embodiments (even if such combination is not explicitly described). In other words, the described embodiments are not mutually exclusive, and substituting one or more embodiments for one another is within the scope of the present disclosure.

[0096] Spatial and functional relationships between elements (e.g., modules, circuit elements, semiconductor layers, etc.) are described using various terms such as "connected," "engaged," "coupled," "adjacent," "next to," "on," "above," "below," and "disposed." Also, when a relationship between a first element and a second element is described in the above disclosure, unless expressly described as "direct," the relationship may be a direct relationship where no other intervening elements exist between the first element and the second element, or an indirect relationship where one or more intervening elements (spatial or functional) exist between the first element and the second element. As used herein, the phrase "at least one of A, B, and C" should be interpreted in the sense of a logical (A or B or C) using a non-exclusive logical OR, and not in the sense of "at least one of A, at least one of B, and at least one of C."

[0097] In some embodiments, the controller is part of a system, and such a system may be part of the examples described above. Such systems may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (e.g., wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling system operation before, during, and after semiconductor wafer or substrate processing. Such electronics may be referred to as a "controller" and may control various components or subcomponents of one or more systems. The controller may be programmed to control any of the processes disclosed herein, depending on the processing requirements and / or type of system. Such processes may include process gas delivery, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and motion settings, wafer transfer to and from the tool, and wafer transfer to and from other transfer tools and / or load locks connected or interfaced with the particular system.

[0098] Broadly, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application-specific integrated circuits (ASICs), and / or one or more microprocessors, i.e., microcontrollers, that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. The operational parameters, in some embodiments, may be part of a recipe defined by a process engineer to implement one or more processing steps in the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0099] The controller, in some embodiments, may be part of, coupled to, or a combination of a computer that is integrated with, coupled to, or otherwise networked to the system. For example, the controller may be in the "cloud" or all or part of a fab host computer system, allowing remote access of wafer processing. The computer may provide remote access to the system to monitor the current progress of a fabrication operation, review the history of past fabrication operations, review trends or performance criteria from multiple fabrication operations, modify parameters of a current process, set up processing steps following the current process, or initiate a new process.

[0100] In some examples, a remote computer (e.g., a server) can provide a process recipe to the system over a network. Such a network may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data. Such data identifies parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool the controller is configured to interface with or control.

[0101] Thus, as discussed above, the controller may be distributed, for example, by having one or more individual controllers networked together and cooperating toward a common purpose (such as the processes and controls described herein). An example of a distributed controller for such a purpose would include one or more integrated circuits on the chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer) and coupled to control the processes in the chamber.

[0102] Exemplary systems may include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a tracking chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0103] As described above, depending on the process step or steps being performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to and from tool locations and / or load ports in a semiconductor fabrication factory. The present disclosure may be realized in the following forms. [Form 1] 1. A base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber, comprising: a first component made of a first material including a metal and a non-metal, the first material having a first coefficient of thermal expansion; a layer coated on the first component and made of a second material, the second material having a second coefficient of thermal expansion; Equipped with the first and second thermal expansion coefficients are different; The thickness of the layer of the second material is between 30 μm and 2 mm. Base plate. [Form 2] The base plate according to aspect 1, The first and second coefficients of thermal expansion of the base plate are within a predetermined range. [Form 3] The base plate according to aspect 1, The first coefficient of thermal expansion of the base plate is greater than the second coefficient of thermal expansion. [Form 4] The base plate according to aspect 1, The first coefficient of thermal expansion of the base plate is less than the coefficient of thermal expansion of the metal. [Form 5] The base plate according to aspect 2, the predetermined range is between a first value and a second value, the second value being greater than the first value; the first coefficient of thermal expansion is closer to the second value than to the first value; the second coefficient of thermal expansion is closer to the first value than to the second value; Base plate. [Form 6] The base plate according to aspect 2, The predetermined range is 6 to 12. [Form 7] The base plate according to aspect 1, the first coefficient of thermal expansion is 11; The second thermal expansion coefficient is 8. Base plate. [Form 8] The base plate according to aspect 1, the metal is aluminum; The nonmetal is silicon carbide. Base plate. [Form 9] The base plate according to aspect 1, The second material is a ceramic material, the base plate. [Form 10] The base plate according to aspect 1, The second material is alumina or yttria, the base plate. [Form 11] The base plate according to aspect 1, a second layer made of a third material disposed on the layer coating the first component; and a third component made of the second material disposed on the second layer; and The base plate further comprises: [Form 12] 12. The base plate according to claim 11, The second layer bonds the third component to the first component, a base plate. [Form 13] 12. The base plate according to claim 11, The second layer conducts heat between the third component and the first component and absorbs shear stresses in a predetermined temperature range for a predetermined period of time, the base plate. [Form 14] 1. A method for manufacturing a base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber, comprising: fabricating a first component of the base plate using a first material including a metal and a non-metal, the first material having a first coefficient of thermal expansion; coating the first component of the base plate with a layer of a second material having a second coefficient of thermal expansion; Including, the first and second thermal expansion coefficients are different; The thickness of the layer of the second material is between 30 μm and 2 mm. method. [Form 15] 15. The method of claim 14, The method, wherein the first and second coefficients of thermal expansion are within a predetermined range. [Form 16] 15. The method of claim 14, The method, wherein the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion. [Form 17] 15. The method of claim 14, The method, wherein the first coefficient of thermal expansion is less than the coefficient of thermal expansion of the metal. [Form 18] 16. The method of claim 15, the predetermined range is between a first value and a second value, the second value being greater than the first value; the first coefficient of thermal expansion is closer to the second value than to the first value; the second coefficient of thermal expansion is closer to the first value than to the second value; method. [Form 19] 16. The method of claim 15, The predetermined range is 6 to 12. [Form 20] 15. The method of claim 14, the first coefficient of thermal expansion is 11; The second thermal expansion coefficient is 8. method. [Form 21] 15. The method of claim 14, selecting aluminum as the metal; selecting silicon carbide as said nonmetal; The method further comprises: [Form 22] 15. The method of claim 14, The method further comprising selecting a ceramic material as the second material. [Form 23] 15. The method of claim 14, The method further comprising selecting alumina or yttria as the second material.

Claims

1. 1. A base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber, comprising: a first component made of a first material including a metal and a non-metal, the first material having a first coefficient of thermal expansion; a layer directly coating the first component and made of a ceramic material, the ceramic material having a second coefficient of thermal expansion; Equipped with the first and second coefficients of thermal expansion are different; the thickness of the layer of ceramic material is between 30 μm and 2 mm; Base plate.

2. 2. The base plate according to claim 1, The first and second coefficients of thermal expansion of the base plate are within a predetermined range.

3. 2. The base plate according to claim 1, The first coefficient of thermal expansion of the base plate is greater than the second coefficient of thermal expansion.

4. 2. The base plate according to claim 1, The base plate, wherein the first coefficient of thermal expansion is less than the coefficient of thermal expansion of the metal.

5. 3. The base plate according to claim 2, the predetermined range is between a first value and a second value, the second value being greater than the first value; the first coefficient of thermal expansion is closer to the second value than to the first value; the second coefficient of thermal expansion is closer to the first value than to the second value; Base plate.

6. 3. The base plate according to claim 2, A base plate, wherein the predetermined range is 6 to 12.

7. 2. The base plate according to claim 1, the first coefficient of thermal expansion is 11; the second coefficient of thermal expansion is 8; Base plate.

8. 2. The base plate according to claim 1, the metal is aluminum; The nonmetal is silicon carbide. Base plate.

9. 2. The base plate according to claim 1, The ceramic material of the base plate is alumina or yttria.

10. 2. The base plate according to claim 1, a second layer made of a third material disposed on the layer coating the first component; and a third component made of the ceramic material disposed on the second layer; and The base plate further comprises:

11. 11. The base plate of claim 10, The second layer bonds the third component to the first component.

12. 11. The base plate of claim 10, The second layer conducts heat between the third component and the first component and absorbs shear stresses in a predetermined temperature range for a predetermined period of time.

13. 1. A method for manufacturing a base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber, comprising: fabricating a first component of the base plate using a first material including a metal and a non-metal, the first material having a first coefficient of thermal expansion; directly coating the first component of the base plate with a layer of ceramic material having a second coefficient of thermal expansion; Including, the first and second coefficients of thermal expansion are different; the thickness of the layer of ceramic material is between 30 μm and 2 mm; method.

14. 14. The method of claim 13, The method, wherein the first and second coefficients of thermal expansion are within a predetermined range.

15. 14. The method of claim 13, The method, wherein the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion.

16. 14. The method of claim 13, The method, wherein the first coefficient of thermal expansion is less than the coefficient of thermal expansion of the metal.

17. 15. The method of claim 14, the predetermined range is between a first value and a second value, the second value being greater than the first value; the first coefficient of thermal expansion is closer to the second value than to the first value; the second coefficient of thermal expansion is closer to the first value than to the second value; method.

18. 15. The method of claim 14, The predetermined range is 6 to 12.

19. 14. The method of claim 13, the first coefficient of thermal expansion is 11; the second coefficient of thermal expansion is 8; method.

20. 14. The method of claim 13, selecting aluminum as the metal; selecting silicon carbide as said nonmetal; The method further comprises:

21. 14. The method of claim 13, The method further comprising selecting alumina or yttria as the ceramic material.

22. 2. The base plate according to claim 1, The base plate, wherein the first material comprises nickel or titanium boron coated carbon fiber and an aluminum matrix.

23. 14. The method of claim 13, The method of claim 1, wherein the first material comprises nickel or titanium boron coated carbon fibers and an aluminum matrix.

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