Mixed metal base plate for improving thermal expansion matching with thermal oxide spray coatings

Abstract

This invention provides a base plate for a substrate support assembly and a method for manufacturing the same, which minimize stress on the spray coating by modifying the dimensional design. [Solution] The base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber comprises a first component made of a first material including metals and nonmetals. The first material has a first coefficient of thermal expansion (CTE). 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 on January 13, 2020. The entire disclosure of the application referenced above is incorporated herein by reference.

[0002] This disclosure generally relates to substrate processing systems, and more particularly to using a mixed - metal baseplate within a processing chamber to improve thermal expansion matching with a spray coat applied on a baseplate.

Background Art

[0003] The background description provided here is for the purpose of generally presenting the content of the present disclosure. Within the scope described in this background art section, research by the inventors named at the present time, as well as aspects of the description that cannot be separately considered as prior art at the time of filing, are not admitted as prior art against the present disclosure, whether explicitly or implicitly.

[0004] Substrate processing systems typically include a plurality of processing chambers (also called process modules) that perform deposition, etching, and other processes 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, the substrate is placed on a substrate support such as a pedestal or electrostatic chuck (ESC) within the processing chamber of the substrate processing system. During deposition, a gas mixture containing one or more precursors is introduced into the processing chamber, and plasma is applied to activate the chemical reaction. During etching, a gas mixture containing etching gas is introduced into the processing chamber, and plasma is applied to activate the chemical reaction. A computer-controlled robot typically transfers the substrate from one processing chamber to another in the order in which the substrate is processed. [Overview of the project]

[0006] The base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber comprises a first component made of a first material including metals and nonmetals. 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 thermal expansion coefficients are within a predetermined range.

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

[0009] In another characteristic, the first thermal expansion coefficient is smaller than that of the metal.

[0010] In other characteristics, the given range is between a first value and a second value. The second value is greater than the first value. The first thermal expansion coefficient is closer to the second value than the first value. The second thermal expansion coefficient is closer to the first value than the second value.

[0011] In another characteristic, the given range is 6 to 12.

[0012] In another characteristic, the thickness of the second material layer is 30 μm to 2 mm.

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

[0014] In other characteristics, the metal is aluminum, and the nonmetal is silicon carbide.

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

[0016] In another characteristic, 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 a layer coating a 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 and first components and absorbs shear stress in a predetermined temperature range over a predetermined period of time.

[0020] In other features, a method for manufacturing a base plate of a substrate support assembly for supporting a semiconductor substrate in a processing chamber comprises manufacturing a first component of the base plate using a first material, including metallic and nonmetallic materials. The first material has a first coefficient of thermal expansion. The method comprises 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 thermal expansion coefficients are within a predetermined range.

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

[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 is 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.

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

[0026] In another feature, the thickness of the layer of the second material is 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] Other fields to which the present disclosure is applicable will become apparent from the detailed description, the claims and the drawings. The detailed description and the specific examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Brief Description of the Drawings

[0032] The present disclosure will be more fully understood from the detailed description and the accompanying drawings.

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

[0034] [Figure 2] Figure 2 shows a second example of a substrate processing system equipped with a processing chamber.

[0035] [Figure 3] Figure 3 shows a third example of a substrate processing system equipped with a processing chamber.

[0036] [Figure 4] Figure 4 is a schematic diagram showing an example of a base plate according to this disclosure that can be used in a processing chamber of a substrate processing system. [Figure 5] Figure 5 is a schematic diagram showing an example of a base plate according to this disclosure that can be used in a processing chamber of a substrate processing system.

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

[0038] [Figure 7] Figure 7 shows a method for manufacturing the substrate of the base plate shown in Figures 4 and 5 according to this disclosure.

[0039] In these drawings, reference numbers may be reused to refer to similar and / or identical elements. [Modes for carrying out the invention]

[0040] The base plate is a fundamental component of the processing chamber where wafers are placed during processing. Typically, the base plate is made of a metal substrate with a spray coating of oxide material covering the outside of the metal substrate. The spray coating is used to protect the base plate (i.e., the metal substrate) from the extreme environment of the processing chamber (for example, to protect the base plate from plasma erosion and arc discharge).

[0041] Depending on the process, the base plate can be used over a wide temperature range, for example, exceeding approximately 100 degrees Celsius. Controlling the stress on the spray coat over the entire operating regime to ensure proper adhesion of the spray coat to the metal substrate and to ensure reduction of 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 this disclosure, by using a mixed metal substrate whose thermal expansion is better matched to that of the spray coat, the stress on the spray coat can be relatively relaxed over the full operating range.

[0042] The base plate is typically made of aluminum with a spray coat of aluminum oxide. The thermal expansion coefficient of aluminum is greater than 20 μm / °Cm. This is significantly greater than the thermal expansion coefficient of aluminum oxide, which is about 8 μm / °Cm. When the oxide layer is applied at high temperatures, the coat is subjected to large tensile stresses at cryogenic temperatures, causing the aluminum substrate to shrink much more than the oxide spray coat.

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

[0044] The teachings of this disclosure are not limited to base plates. Rather, the teachings can be extended and applied to various other components of a processing chamber that are subjected to stress due to the extreme environment of the processing chamber, typically including metal substrates covered with a spray coat of oxide layers. These components may also be manufactured using mixed metal substrates coated with a ceramic layer, thereby improving the thermal expansion matching between the substrate and the ceramic layer and reducing stress on these components. Non-limiting examples of such components include the inner walls of the processing chamber, various annular ring-shaped components used in the processing chamber, shower heads, and the like.

[0045] This disclosure is structured as follows: First, to understand the harsh environment within the processing chamber and the diverse components to which the teachings of this disclosure can be applied, examples of different processing chambers are shown and described with reference to Figures 1-3. Next, metal matrix composite (MMC) materials are described in detail. Then, exemplary designs of base plates according to this disclosure are shown and described with reference to Figures 4-5. Subsequently, exemplary methods for manufacturing base plates according to this disclosure are shown and described with reference to Figures 6-7.

[0046] Figure 1 shows an example of a substrate processing system 100 comprising a processing chamber 102. Although the example is described in the context of plasma-enhanced chemical vapor deposition (PECVD), the teachings of this disclosure can be applied to other types of substrate processing, including atomic layer deposition (ALD), plasma-enhanced ALD (PEALD), CVD, or other processes including etching. The system 100 comprises a processing chamber 102 surrounding the other components of the system 100 and containing RF plasma (if used). The processing chamber 102 comprises an upper electrode 104 and an electrostatic chuck (ESC) 106 or other substrate support. During operation, a substrate 108 is placed on the ESC 106.

[0047] For example, the upper electrode 104 may include a gas distribution device 110, such as a showerhead, for introducing and distributing process gases. The gas distribution device 110 may include a stem portion, one end of which is connected to the upper 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, spaced apart from the upper surface of the processing chamber 102. The substrate-facing surface or faceplate of the base portion of the showerhead includes a plurality of holes through which vaporized precursor, process gas, or purge gas flows. Alternatively, the upper electrode 104 may include a conductive plate, and the process gas can be introduced in a different manner.

[0048] The ESC106 comprises a base plate 112 acting as a lower electrode. The base plate 112 may include one or more channels 118 for circulating a 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 placed 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 multizone heater (not shown)).

[0049] When plasma is used, the RF generation system 120 generates an RF voltage and outputs it 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. In just one example, 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] The gas supply system 130 includes one or more gas sources 132-1, 132-2, ..., and 132-N (collectively referred to as gas source 132), where N is an integer greater than zero. The gas sources 132 are connected to the manifold 140 by valves 134-1, 134-2, ..., and 134-N (collectively referred to as valve 134) and mass flow controllers 136-1, 136-2, ..., and 136-N (collectively referred to as mass flow controller 136). The steam supply system 142 supplies the vaporized precursor to the manifold 140 or another manifold (not shown) connected to the processing chamber 102. The output of the manifold 140 is supplied to the processing chamber 102.

[0051] The temperature controller 150 can communicate with the coolant assembly 154 and control the flow of coolant through the channel 118. For example, the coolant assembly 154 may 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 channel 118 to cool the ESC 106. In some applications, if the ceramic plate 114 includes a heater 152, the temperature controller 150 may be connected to a plurality of thermal control elements (TCEs) 152 located on the ceramic plate 114. The temperature controller 150 can be used to control the plurality of TCEs 152 to control the temperatures of the ESC 106 and the substrate 108. The valve 156 and pump 158 can be used to discharge the reactant from the processing chamber 102. The system controller 160 controls the components of the system 100.

[0052] Figure 2 shows another example of the substrate processing system 200. The substrate processing system 200 includes a coil drive circuit 211. In some examples, the coil drive circuit 211 includes an RF source 212, a pulse circuit 214, and a tuning circuit (i.e., a 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 understood, the pulse circuit 214 and the RF source 212 can be combined or separate in some embodiments.

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

[0054] A dielectric window 224 is positioned along the upper side of the processing chamber 228. The processing chamber 228 includes a substrate support (or base) 232 that supports the substrate 234. The substrate support 232 may include an electrostatic chuck (ESC), a mechanical chuck, or other types of chucks. A process gas is supplied to the processing chamber 228, and 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 during operation and control the ion energy.

[0055] A gas supply system 256 can be used to supply the process gas mixture to the processing chamber 228. The gas supply system 256 may include a process and inert gas source 257, a gas metering system 258 including valves and a mass flow controller, and a manifold 259. A gas injector 263 may be located in the center of the dielectric window 224 and is used to inject the gas mixture from the gas supply system 256 into the processing chamber 228. Additionally or alternatively, the gas mixture may 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. The exhaust system 265 includes valves 266 and pumps 267 for controlling the pressure in the processing chamber and / or for removing the reactant from the processing chamber 228 by purging or discharge.

[0057] The etching process can be controlled using the controller 254. The controller 254 monitors system parameters and controls the supply of the gas mixture, the striking, maintenance, and extinction of the plasma, the removal of the reactant, the supply of cooling gas, and so on. In addition, as described below, the controller 254 can control various aspects such as the coil drive circuit 210, the RF source 250, and the bias matching circuit 252.

[0058] Figure 3 shows a processing chamber 300 for etching layers 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 the chamber sidewalls 308, the chamber bottom 310, and the lower surface of the 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 the 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 supplying process gas to the upper chamber region 304. In some examples, the process gas is supplied through one or more spaced holes 323 at an acute angle upward with respect to the plane containing the gas distribution device 314, although other angles / directions may also be used. In some examples, gas flow channels 334 within the first annular support 321 supply gas to one or more spaced holes 323.

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

[0061] The substrate support 322 is placed in the lower chamber region 304. In some examples, the substrate support 322 includes an electrostatic chuck (ESC), but other types of substrate supports can be used. The substrate 326 is placed on the 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), but any other suitable substrate support temperature control system may be used.

[0062] In some examples, the gas distribution device 314 includes a showerhead (e.g., a plate 328 having multiple spaced holes 327). The multiple spaced holes 327 extend from the top surface of the plate 328 to the bottom 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 electrodes made of a conductive material embedded in it.

[0063] One or more induction coils 340 are positioned around the outer portion of the dome 318. When excited, one or more induction coils 340 generate an electromagnetic field inside the dome 318. In some examples, upper and lower coils are used. A gas injector 342 injects one or more gas mixtures from a gas supply system 350-1. In some examples, the gas supply 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 158, but other types of gas supply systems may be used. A gas splitter (not shown) can be used to change the flow rate of the gas mixture. Another gas supply system 350-2 can be used to supply etching gas or an etching gas mixture to the gas flow channels 329 and / or 334 (in addition to or instead of etching gas from the gas injector 342).

[0064] In some examples, the gas injector 342 includes a central injection location that directs the gas downward and one or more lateral injection locations that inject the gas at an angle to the downward direction. In some examples, the gas delivery system 350-1 delivers a first portion of the gas mixture to the central injection location of the gas injector 342 at a first flow rate and a second portion of the gas mixture to the lateral injection locations of the gas injector 342 at a second flow rate. In other examples, different gas mixtures are delivered by the gas injector 342. In some examples, the gas delivery system 350-1 delivers the 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 output to one or more induction coils 340. 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 one or more induction coils 340. In some examples, a gas distribution device 314 is connected to a reference potential such as earth. Valves 378 and pumps 380 can be used to control the pressure in the lower and upper chamber regions 302, 304 and to discharge the coolant.

[0066] The controller 376 communicates with the gas supply systems 350-1 and 350-2, the valve 378, the pump 380, and the plasma generator 370 to control the flow of process gas, purge gas, RF plasma, and chamber pressure. In some examples, the plasma is maintained inside the dome 318 by one or more induction coils 340. One or more gas mixtures are introduced from the top of the chamber using a gas injector 342 (and / or hole 323), and the plasma is confined within the dome 318 using a gas distribution device 314.

[0067] By confining the plasma within the dome 318, volumetric recombination of plasma species becomes possible, allowing the desired etchant species to be emitted through the gas distribution device 314. In some examples, there is no RF bias applied to the substrate 326. As a result, there is no active sheath on the substrate 326, and ions are not striking the substrate with finite energy. A certain amount of ions diffuse from the plasma region through the gas distribution device 314. However, the amount of plasma diffusing is an order of magnitude less than the plasma located inside the dome 318. Most of the ions in the plasma are lost by volumetric recombination at high pressure. Surface recombination losses on the upper 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, which includes an RF generator 386 and a matching network 388. The RF bias can be used to generate 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 may be used to control the RF bias.

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

[0070] MMCs are fabricated 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 synthesize composites exhibiting both low density and high strength. However, carbon reacts with aluminum, forming brittle, water-soluble compounds on the fiber surface. To prevent this reaction, the carbon fibers are coated with nickel or titanium boride.

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

[0072] Reinforcement is not always useful for purely structural tasks (e.g., reinforcing compounds), but is also used to alter physical properties such as wear resistance, friction coefficient, and thermal conductivity. Reinforcement can be continuous or discontinuous. Discontinuous MMCs can be isotropic and can be processed using standard metalworking techniques such as extrusion, forging, or rolling. In addition, they can be machined using conventional techniques, but may require further tooling using techniques such as polycrystalline diamond tools (PCD).

[0073] Continuous reinforcement uses monofilament wires or fibers such as carbon fibers or silicon carbide. Because the fibers are embedded in the matrix in a specific direction, an anisotropic structure is obtained 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 manufacturing can generally take three forms: solid, liquid, and vapor. MMCs are fabricated at high temperatures for diffusion bonding at the fiber / matrix interface. As they cool to ambient temperature, residual stress is generated in the composite due to mismatches between the coefficients of the metal matrix and fibers. Residual stress during manufacturing significantly affects the mechanical behavior of the MMC under all loading conditions. In some cases, thermal residual stress can be high enough to initiate plastic deformation within the matrix during the manufacturing process.

[0075] Methods for manufacturing solid-state materials include powder blending and solidification (powder metallurgy). In this method, powder metal and discontinuous reinforcement are mixed and joined through processes of compression, degassing, and thermomechanical treatment, sometimes via hot isostatic pressing (HIP) or extrusion. Another method for manufacturing solid-state materials is foil diffusion bonding. In this method, layers of metal foil are sandwiched between long fibers and then pressed to form a matrix.

[0076] Liquid manufacturing methods include electroplating and electroforming. In these methods, a solution containing metal ions filled with reinforcing particles is co-deposited to form a composite material. Another liquid manufacturing method is agitation casting. In this method, discontinuous reinforcement can be agitated into molten metal and allowed to solidify. In pressurized impregnation, for example, gas pressure is used to impregnate the molten metal into the reinforcement. In squeeze casting, molten metal is poured into a mold in which fibers are pre-placed. In spray deposition, molten metal is sprayed onto a continuous fiber substrate. In reaction methods, a chemical reaction occurs between one reactant that forms the matrix and the other reactant that forms the reinforcement.

[0077] Another method involves heating a powder mixture to a semi-solid state and applying pressure to form a composite, known as a semi-solid powder processing method. In physical vapor deposition, the coating is achieved by the fibers passing through a thick cloud of vaporized metal. In in-situ fabrication methods, the coating is achieved by the fibers passing through a thick cloud of vaporized metal.

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

[0079] Compared to conventional polymer matrix composites, MMCs are fire-resistant, can operate over a wider temperature range, do not absorb moisture, have superior electrical and thermal conductivity, are resistant to radiation damage, and do not exhibit gas emissions. On the other hand, MMCs tend to be more expensive, and fiber-reinforced materials can be difficult to manufacture, resulting in limited available experience in their use.

[0080] Figures 4 and 5 schematically illustrate an example of a base plate 400 according to this 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 Figure 4, the base plate 400 comprises a mixed metal substrate 402 (shown in detail in Figure 5) covered with a ceramic coating 404. For example, the substrate 402 may include 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 include aluminum oxide (e.g., alumina or Al2O3) spray-coated onto the substrate 402.

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

[0082] In particular, in the example shown, the CTE of the composite material is significantly lower than the CTE of aluminum, which is about 22, and closer to the CTE of alumina, which is about 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, together with a layer of alumina spray-coated onto the substrate 402. For example, the composite material shown in the right box of Figure 5 results in a composite material in which the density of the reinforcing material (e.g., silicon carbide) 410 in the metal (e.g., aluminum) 412 has a CTE of about 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 about 8. This combination of using a substrate 402 made of a composite material formed of aluminum and silicon carbide having a CTE of about 11 and using a spray coat of alumina having a CTE of about 8 minimizes stress on the base plate 400 in the processing chamber. As a result, the combination of aluminum and silicon carbide spray-coated with alumina prevents cracking of the alumina (i.e., ceramic material 404) layer coated on the substrate 402 due to better matching of the CTEs of the substrate 402 (e.g., aluminum and silicon carbide) and the ceramic material 404 (e.g., alumina).

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

[0084] For example, a given range (e.g., 6 to 12) has a first value (e.g., 6) and a second value (e.g., 12) that is greater than the first value. The first CTE has a value (e.g., 11) within the given range (e.g., 6 to 12). The second CTE has a value (e.g., 8) within the given 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 given range (e.g., 6 to 12) than the first value (e.g., 8) within the given 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 given range (e.g., 6 to 12) than the second value (e.g., 12) within the given range (e.g., 6 to 12). In 454, method 450 includes using a coated base plate (for example, the base plate 400 shown in Figures 4 and 5) in a processing chamber.

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

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

[0087] For example, it should be noted that the manufacture of a base plate containing a combination of aluminum and silicon carbide, with an alumina coating, is not simply a design choice or the result of routine experimentation. Rather, it is the result of a thorough and extensive investigation into various materials, their properties, and their behavior in various combinations and under the vastly different thermal, chemical, and electrical operating conditions that occur in different substrate processing systems. This disclosure satisfies a long-held need in the industry: a method to minimize stress on the coating on the base plate and prevent cracking of the coating. This disclosure provides the unexpected result of minimizing stress on the coating on the base plate and preventing cracking of the coating by maintaining the CTE of both the substrate and the base plate coating within a narrow range as described above.

[0088] The base plate of the MMC material can be manufactured using a variety of processes, including casting, machining, and 3D printing. Furthermore, in some examples, the coating material on the MMC material may also include other materials, such as yttria (i.e., yttrium oxide or Y2O3), which can be used when manufacturing some of the components of a processing chamber.

[0089] One advantage of using MMC material for the base plate is that a thicker spray coat can be applied to the base plate than when the base plate is made of a metal such as aluminum. For example, the thickness of the coating material can be approximately 30 μm to 2 mm. The limitation on the thickness of the spray coat on an aluminum base plate is the stress accumulated in the coating film (which induces cracking of the spray coat). This stress is related to the lattice mismatch and adhesive properties between the substrate (metal) and the coating film (among other factors). By changing the substrate of the base plate from metal to MMC, the stress on the coating can be reduced, allowing for thicker films.

[0090] Thicker film coatings can have multiple applications. For example, thicker films can simply be used for higher voltage standoffs, enabling higher RF voltages for ESCs. Furthermore, in processes carried out within a processing chamber, if some amount of film is slightly etched off during plasma processing, thicker films can extend the life of the base plate. Additionally, if it is necessary to remove part of the film to clean the ESC, thicker films can extend the life of the ESC. Thinner spray coatings may also be desirable for several reasons, such as reducing the overall temperature drop of the coating (i.e., enabling lower-temperature wafers) and for better capacitance matching to improve RF performance. Other advantages are also anticipated.

[0091] A further advantage of using MMC material for the base plate is that the improved CTE matching between the base plate and the ceramic plate can help delaminate the bonding layer placed between the base plate and the ceramic plate, and can also prevent cracking of the ceramic plate. For example, in Figure 1, the bonding layer 116 placed between the base plate 112 and the ceramic plate 114 serves multiple purposes, including physically bonding the base plate 112 and the ceramic plate 114, improving heat conduction between the base plate 112 and the ceramic plate 114, and maintaining sufficient elasticity to withstand shear stress over a wide temperature range (shear stress is caused by thermal expansion and contraction of the base plate 112 and the ceramic plate 114 due to temperature changes during substrate processing).

[0092] To achieve these objectives, selecting the material composition and thickness for the bonding layer 116 can be difficult if the CTEs of the base plate 112 and the ceramic plate 114 differ significantly. Specifically, the above thermal and elastic requirements impose strict constraints on the material selection 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 stress caused by the 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 strict constraints being met, which can cause downtime and further increase costs.

[0093] Using MMC material for a base plate 112 having a CTE that precisely matches that of the ceramic plate 114 significantly reduces the aforementioned constraints on the material used for the bonding layer 116. The base plate 112 is similar to the base plate 400 shown in Figures 4 and 5 and can be coated with a ceramic coating 404 as shown in Figures 4 and 5. Furthermore, the ceramic coating 404 and the ceramic plate 114 can contain the same material. Thus, the CTE of the base plate 112 matches that of the ceramic plate 114 to the same extent that the CTE of the base plate 400 matches that of the ceramic coating 404 on the base plate 400.

[0094] CTE matching between the base plate 112 and the ceramic plate 114 allows for the selection of a wide variety of materials for the bonding layer 116, each 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, which involves undesirable glass transitions in the bonding layer 116, may still be applicable due to improved CTE matching (i.e., not necessarily causing delamination). The bonding layer 116 does not delaminate over a relatively wide temperature range. The bonding layer 116 absorbs shear stress over a relatively long period (e.g., the lifespan of the ESC) over a relatively wide temperature range. Using an MMC material for the base plate 112 with a CTE that closely matches the CTE of the ceramic plate 114 can also reduce the risk of cracking in the ceramic plate 114. As a result, the cost of the ESC is reduced, and the lifespan and reliability of the ESC are improved.

[0095] The foregoing description is purely illustrative and is not intended to limit the Disclosure, its application, or its use in any way. The broad teachings of this Disclosure can be implemented in various forms. Thus, while this Disclosure includes specific examples, the true scope of this Disclosure should not be limited to such examples, as other modifications will become apparent when considering the drawings, specification, and the claims below. 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 this Disclosure. Furthermore, while each embodiment is described above as having specific features, it is possible to implement one or more of these features described in relation to any embodiment of this Disclosure in other embodiments and / or combine them with any feature of any other embodiment (even if such combinations are not explicitly described). In other words, the described embodiments are not mutually exclusive, and substituting one or more embodiments with one or more is within the scope of this Disclosure.

[0096] The spatial and functional relationships between elements (e.g., modules, circuit elements, semiconductor layers, etc.) are described using a variety of terms, such as “connected,” “engaged,” “joined,” “adjacent,” “next to,” “above,” “upwards,” “below,” and “positioned.” Furthermore, when a relationship between a first element and a second element is described in the above disclosure, unless it is explicitly described as “direct,” the relationship may be a direct relationship in which no other intervening elements exist between the first and second elements, or it may be an indirect relationship in which one or more intervening elements exist (spatially or functionally) between the first and second elements. As used herein, the expression “at least one of A, B, and C” should be interpreted in the sense of logic (A or B or C) using non-exclusive logic 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 a system may comprise semiconductor processing equipment including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (such as wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronic equipment for controlling system operation before, during, and after processing of semiconductor wafers or substrates. Such electronic equipment may be referred to as a “controller” and may control various components or sub-components of one or more systems. Depending on the processing requirements and / or the type of system, the controller may be programmed to control any of the processes disclosed herein. Such processes include supplying processing gases, setting temperature (e.g., heating and / or cooling), setting pressure, setting vacuum, setting power, setting radio frequency (RF) generator settings, setting RF matching circuit settings, setting frequency, setting flow rate, setting fluid supply, setting position and operation, loading and unloading wafers to and from tools, and loading and unloading wafers to and from other transport tools and / or load locks connected to or interlocked with a particular system.

[0098] In a broad sense, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive and 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, chips defined as digital signal processors (DSPs), application-specific integrated circuits (ASICs), and / or one or more microprocessors, i.e., microcontrollers that execute program instructions (e.g., software). Program instructions are instructions communicated to the controller in the form of various individual settings (or program files) that may define operating parameters for performing a particular process on or for a semiconductor wafer or for a system. In some embodiments, the operating parameters may be part of a recipe defined by a process engineer to realize 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] In some embodiments, the controller may be part of a computer that is integrated with or coupled to the system, or otherwise networked to the system, or coupled to such a computer, or a combination thereof. For example, the controller may be in the “cloud,” or it may be all or part of the fab host computer system. This enables remote access to wafer processing. The computer may enable remote access to the system to monitor the current progress of fabrication operations, review the history of past fabrication operations, review trends or performance criteria from multiple fabrication operations, change the parameters of the current process, set processing steps following the current process, or start a new process.

[0100] In some examples, a remote computer (e.g., a server) can provide process recipes 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 for the 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 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 tools the controller is configured to work with or control.

[0101] Therefore, as described above, the controller may be distributed by comprising, for example, one or more individual controllers that are networked together and cooperate toward a common purpose (such as the processes and controls described herein). An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber that communicate with one or more integrated circuits that are remotely located (for example, at the platform level or as part of a remote computer) and combined to control the processes in the chamber.

[0102] Exemplary systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etching chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, tracking chambers or modules, and any other semiconductor processing systems that may be used in connection with or for the fabrication and / or manufacture of semiconductor wafers.

[0103] As described above, depending on one or more process steps 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 for material handling to load and unload wafer containers to and from tool locations and / or load ports within the semiconductor manufacturing plant.

Claims

1. A base plate for a substrate support assembly for supporting a semiconductor substrate in a processing chamber, A first component made of a first material including metals and nonmetals, wherein the first material comprises a first component having a first coefficient of thermal expansion, A layer made of a second material, which coats the first component, wherein the second material has a second coefficient of thermal expansion. Equipped with, The first and second thermal expansion coefficients are different. Base plate.

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

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

4. A base plate according to claim 1, A base plate having a first thermal expansion coefficient that is smaller than the thermal expansion coefficient of the metal.

5. A base plate according to claim 2, The predetermined range is between a first value and a second value, where the second value is 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 the second value. Base plate.

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

7. A base plate according to claim 1, A base plate in which the thickness of the layer of the second material is 30 μm to 2 mm.

8. A base plate according to claim 1, The first coefficient of thermal expansion is approximately 11. The second coefficient of thermal expansion is approximately 8. Base plate.

9. A base plate according to claim 1, The aforementioned metal is aluminum. The aforementioned nonmetal is silicon carbide. Base plate.

10. A base plate according to claim 1, The second material is a ceramic material, which is a base plate.

11. A base plate according to claim 1, The second material is alumina or yttria, which is the base plate.

12. A base plate according to claim 1, A second layer made of a third material is disposed on the layer coating the first component, A third component made of the second material and placed on the second layer A base plate that further enhances the features.

13. A base plate according to claim 12, The second layer is a base plate that joins the third component to the first component.

14. A base plate according to claim 12, A base plate wherein the second layer conducts heat between the third component and the first component and absorbs shear stress in a predetermined temperature range over a predetermined period of time.

15. A method for manufacturing a base plate for a substrate support assembly to support a semiconductor substrate in a processing chamber, Manufacturing a first component of the base plate using a first material comprising metals and nonmetals, wherein the first material has 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. Includes, The first and second thermal expansion coefficients are different. method.

16. The method according to claim 15, A method wherein the first and second coefficients of thermal expansion are within a predetermined range.

17. The method according to claim 15, A method wherein the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion.

18. The method according to claim 15, A method wherein the first coefficient of thermal expansion is smaller than the coefficient of thermal expansion of the metal.

19. The method according to claim 15, The predetermined range is between a first value and a second value, where the second value is 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 the second value. method.

20. The method according to claim 16, A method wherein the predetermined range is 6 to 12.

21. The method according to claim 15, A method wherein the thickness of the layer of the second material is 30 μm to 2 mm.

22. The method according to claim 15, The first coefficient of thermal expansion is approximately 11. The second coefficient of thermal expansion is approximately 8. method.

23. The method according to claim 15, The selection of aluminum as the aforementioned metal, The selection of silicon carbide as the aforementioned nonmetal and Methods that further include this.

24. The method according to claim 15, A method further comprising selecting a ceramic material as the second material.

25. The method according to claim 15, A method further comprising selecting alumina or yttria as the second material.

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