Cleaning method for removing parasitic grown silicon carbide, internal components of epitaxial process chambers, and epitaxial process systems

Abstract

A cleaning method for removing parasitic silicon carbide from an internal component of an epitaxial process chamber for silicon carbide epitaxial growth, the internal component comprising a pyrolytic carbon coating (105) having a highly layered microstructure and containing less than 5 ppm of impurities, the method comprising the steps of: 1a) placing the internal component in a halogen-containing gas at a temperature of 150°C to 1700°C to convert the parasitic silicon carbide present on the internal component into carbide-derived carbon (CDC) material, wherein the halogen-containing gas is chlorine, bromine, or a combination of two or more thereof that can be mixed with nitrogen, argon, helium, or a combination thereof; or 1b) at a temperature of 1000°C to 2400°C and at 1×10 ‑10 Under a pressure of millibar to 500 millibars, the internal component is placed in an inert gas to convert the parasitic silicon carbide present on the internal component into the CDC material; 2) the CDC material is removed from the internal component to obtain an outer surface of the internal component that is free of or substantially free of the CDC material. An internal component of an epitaxial process chamber for the epitaxial growth of silicon carbide is adapted to be cleaned by the cleaning method described above. An epitaxial process system includes a controller and an epitaxial process chamber, wherein the epitaxial process chamber includes at least one internal component, and wherein the controller is configured to operate the epitaxial process chamber in a cleaning mode, wherein parasitic silicon carbide on the at least one internal component in the epitaxial process chamber is removed according to the cleaning method described above.

Description

Technical Field

[0001] The present invention relates to a cleaning method for removing parasitic silicon carbide from the internal components of an epitaxial process chamber used for silicon carbide epitaxial growth, the internal components of the epitaxial process chamber, and an epitaxial process system. Background Technology

[0002] The silicon carbide epitaxial equipment market is experiencing rapid growth, primarily driven by the increasing electrification of the automotive industry. However, challenges arise in the chemical vapor deposition (CVD) process for silicon carbide epitaxial layers on silicon carbide wafers. Epitaxial layers tend to be deposited on both the surface of the wafer carrier or susceptor and internal components within the cavity, even when such simultaneous deposition is not necessary.

[0003] The accumulation of these parasitic or unnecessary silicon carbide layers (also known as parasitic silicon carbide) can lead to particle emission and gas flow interruptions, significantly impacting the quality of the epitaxial layer. Furthermore, parasitic silicon carbide can cause dimensional problems because the parasitic silicon carbide layers can grow very thick, hindering part movement and / or placement. Therefore, these parasitic silicon carbide layers must be periodically removed from the surface of the part. This removal process is not easily achieved by chemical methods, mechanical methods, or a combination of both to ensure part repeatability and continued availability.

[0004] Unlike silicon epitaxy, where frequent etching of parasitic silicon deposits can be removed with HCl, polycrystalline silicon carbide (SiC) coated graphite is used to protect the process chamber from other exposed graphite.

[0005] The degradation problem primarily arises because the wafer substrate or internal components (such as graphite or silicon carbide-coated graphite) within the epitaxial chamber are susceptible to etching and degradation in the high-temperature epitaxial environment containing hydrogen. In epitaxial processes, hydrogen is used in the etching or baking steps prior to silicon carbide deposition. This hydrogen erosion can cause problems with uncoated porous graphite components used in the epitaxial process chamber, leading to carbon particle contamination within the chamber.

[0006] Furthermore, uncoated graphite is porous and tends to trap and release impurities, thus affecting the quality of silicon carbide epitaxy. Additionally, when the temperature exceeds approximately 1450°C, silicon atoms within the silicon carbide-coated graphite component may escape from the silicon carbide coating surface and deposit onto the silicon carbide wafer surface, thereby disrupting the silicon carbide epitaxial process.

[0007] To address these challenges, metal carbide coatings such as niobium carbide (NbC) and tantalum carbide (TaC) have been used as protective coating materials. However, both NbC-coated and TaC-coated graphite components are very expensive options. Furthermore, these materials offer better protection for graphite because they do not sublimate and leave TaC or NbC on the back side of the SiC wafer, unlike SiC when heated above 1600°C.

[0008] To address the problem of cleaning parasitic silicon carbide layers or films from carbide-coated graphite components or substrates, a combination of chemical etching and mechanical methods has been employed. Patent US 11028474 B2 discloses a method using a mixture of fluorine and inert gases within a temperature range of 200°C to 500°C.

[0009] The thickness and distribution of parasitic silicon carbide layers or granular layers on graphite components are typically highly uneven. Incomplete removal of parasitic silicon carbide in one area during chemical cleaning can expose the graphite substrate to etching gases in another area. Both ClF3 and F2 gases can etch and degrade the graphite substrate.

[0010] To protect graphite, pyrolytic carbon (PyC) can be used as a coating on the substrate. However, ClF3 and F2 gases can still etch the pyrolytic carbon layer. While the etching process can be modified and additional steps introduced, the entire cleaning process becomes complex, and precise temperature control is crucial.

[0011] Mechanical polishing or grinding of parasitic silicon carbide on coated graphite components is an extremely challenging task, inevitably carrying the risk of causing extensive surface damage to the coated components, including silicon carbide-coated graphite, tantalum carbide-coated graphite, niobium carbide-coated graphite, and pyrolytic carbon-coated graphite components. Existing methods for removing parasitic silicon carbide (whether chemical or mechanical) damage the tantalum carbide coating, the original silicon carbide coating, the pyrolytic carbon coating, and the graphite component, thereby shortening the lifespan of these coatings. In particular, mechanical grinding methods for removing parasitic silicon carbide layers from tantalum carbide-coated graphite components are currently unacceptable.

[0012] To protect the graphite components used in the silicon carbide epitaxial process chamber, silicon carbide and tantalum carbide coatings are deposited on the surface of the graphite components. However, current methods such as cleaning the parasitic silicon carbide layer or particles on the surface of the protective coating with ClF3, NF3, Cl2, or HCl, or even machining, always damage the two protective layers (silicon carbide and titanium carbide layers). Therefore, the lifespan of silicon carbide coated graphite components and tantalum carbide coated components is very short.

[0013] Therefore, a solution is needed to remove parasitic silicon carbide from the interior of the epitaxial process chamber and / or the surface of internal components used for silicon carbide epitaxial growth in order to address one or more of the above-mentioned problems.

[0014] Purpose

[0015] Therefore, the object of the present invention is to provide an improved cleaning method for removing parasitic silicon carbide from the internal components of an epitaxial process chamber.

[0016] Another object of the present invention is to provide an improved cleaning method for removing parasitic silicon carbide from the internal components of an epitaxial process chamber, wherein the cleaning method is capable of cleaning the silicon carbide (SiC) process chamber in situ by selectively removing the parasitic silicon carbide from the internal components of the chamber. Summary of the Invention

[0017] According to a first aspect of the present invention, the above-mentioned objective is achieved. This aspect relates to a cleaning method for removing parasitic silicon carbide from an internal component of an epitaxial process chamber used for silicon carbide epitaxial growth, the internal component comprising a pyrolytic carbon coating, wherein the pyrolytic carbon coating has a highly layered microstructure and contains less than 5 ppm of impurities, the method comprising the following steps:

[0018] 1a) The internal component is placed in a halogen-containing gas at a temperature of 150°C to 1700°C to convert parasitic silicon carbide present in the internal component into carbide-derived carbon (CDC) material, wherein the halogen-containing gas is chlorine, bromine, or a combination of two or more thereof that can be mixed with nitrogen, argon, helium, or a combination thereof, or

[0019] 1b) At temperatures between 1000°C and 2400°C and 1×10 -10 The internal components are placed in an inert gas at pressures from millibar to 500 millibar to convert the parasitic silicon carbide present in the internal components into the CDC material.

[0020] 2) Remove the CDC material from the internal component to obtain an outer surface of the internal component that contains no or substantially no CDC material.

[0021] A pyrolytic carbon (PyC) layer serves as a protective layer for the internal components. The PyC layer seals the porous surface of the internal components and reduces the likelihood of impurities being trapped and subsequently released from the pores. Furthermore, the PyC layer protects the internal components from chemical etching during the etching process, thereby minimizing damage during the hydrogen-based silicon carbide wafer etching process.

[0022] There may be two variations: a PyC layer or a PyC coating. The first variation has a monolithic structure, meaning the coating has a uniform, continuous, and seamless structure throughout the process. Therefore, the coating does not contain distinct carbon layers.

[0023] In the second variant of the PyC coating used in this invention, the PyC coating has a highly layered microstructure. "Highly layered microstructure" means that the PyC coating comprises multiple distinct layers that are arranged in a systematic or repetitive manner over the entire thickness of the PyC coating, wherein there is a significant difference between two adjacent layers.

[0024] The PyC coating used in this invention contains less than 5 ppm of impurities, preferably less than 1 ppm. Impurities can be any substance other than carbon, such as metals, silicon, phosphorus, nitrogen, oxygen, and sulfur.

[0025] The highly layered microstructure and impurities of less than 5 ppm in the PyC coating significantly reduce its susceptibility to oxidation. In other words, the PyC coating better resists oxidizing conditions, allowing internal components containing the PyC coating to be cleaned more efficiently while minimizing the risk of damaging the PyC coating, thereby extending the lifespan of the internal components.

[0026] Depositing PyC layers on internal components is less complex and more economical than depositing silicon carbide, niobium carbide, or tantalum carbide on graphite as a coating.

[0027] The cleaning method according to the present invention removes parasitic silicon carbide from the surface of internal components without damaging the pyrolytic carbon coating on the internal components. Therefore, the pyrolytic carbon-coated internal components can be reused multiple times for silicon carbide epitaxial processes.

[0028] The cleaning method according to the invention provides a relatively simple approach that uses a halogen-containing gas (such as chlorine) to convert parasitic silicon carbide deposited on the surface of a pyrolytic carbon-coated internal component into carbon. These so-called carbide-derived carbon (CDC) layers can be removed from the surface of the PyC-coated internal component under relatively easy and relatively mild conditions without damaging the PyC coating.

[0029] Furthermore, the claimed method offers the possibility of applying high temperatures in the first step of the cleaning process. The advantage of this is that the total time required to complete the cleaning process can be significantly reduced compared to known cleaning processes, because the higher temperature in the first step leads to a faster conversion of SiC into CDC material and reduces the cooling time between SiC deposition in the CVD process and the first step of the claimed cleaning method.

[0030] As previously mentioned, mechanically polishing or grinding parasitic silicon carbide on coated graphite parts is an extremely challenging task, posing a risk of causing extensive surface damage to the coated parts. However, CDC material is much softer than parasitic silicon carbide, and this results in the significantly reduced risk of damaging internal parts when mechanically (or manually) removing the CDC material from internal parts. In other words, mechanical removal of the CDC material becomes a more attractive option due to the cleaning method according to the present invention.

[0031] Other methods exist for converting parasitic SiC into CDC materials, such as hydrothermal decomposition, but these methods can damage the PyC coating during the process due to the formation of SiO2. Preventing this would be very complex.

[0032] The first step of the cleaning method, either step 1a) or step 1b), can not only mechanically / manually remove CDC material, but also chemically remove CDC without damaging the coating by using a pyrolytic carbon coating instead of a traditional metal carbide coating (such as silicon carbide or tantalum carbide).

[0033] Preferably, placing the internal components in a halogen-containing gas in step 1a) is performed at a temperature in the range of 390°C to 700°C, more preferably in the range of 450°C to 600°C.

[0034] The advantage of step 1a) is that the resulting CDC material retains the original shape and crystal surface morphology of silicon carbide (SiC), but removes silicon atoms from the crystal structure, resulting in atomic vacancies. This unique crystal structure of the CDC material exhibits different oxidation behavior compared to the pyrolytic carbon coating on internal components.

[0035] The advantage of step 1b) is that the epitaxial process system or its components do not need to be compatible with halogen-containing gases (such as Cl2). It is possible that the system or its components require only limited redesign to withstand temperatures above 1600 °C.

[0036] Converting parasitic SiC on a pyrolytic carbon-coated component into CDC material is also known as selective etching, because the process conditions of step 1a) or step 1b) etch the parasitic SiC and keep the PyC coating intact.

[0037] Due to the specific properties of the aforementioned pyrolytic carbon coating, only CDC material can be removed during step 2) of the claimed method.

[0038] The proposed method is also known as selective oxidation because it efficiently oxidizes the CDC material while maintaining the integrity of the underlying PyC coating. A suitable oxidation temperature window is required to allow selective oxidation between the CDC material and the substrate (such as the PyC coating). High oxidation temperatures will oxidize not only the CDC material but also the substrate. Low oxidation temperatures may not effectively oxidize the CDC material to avoid oxidizing the substrate material. The oxidation resistance of the substrate material depends on how high the oxidation temperature is. Placing the CDC material in an oxygen-containing gas can oxidize the CDC material but may also oxidize the substrate material, such as the PyC coating or graphite or metal carbides.

[0039] The oxidation initiation temperature of the CDC material obtained in steps 1a) and 1b) is significantly lower than that of graphite and pyrolytic carbon. Therefore, the CDC material can be effectively removed from the pyrolytic carbon coating surface, for example, by oxidizing it with oxygen-containing gas, while minimizing the oxidation of both pyrolytic carbon and graphite. This not only enables the reuse of pyrolytic carbon-coated graphite components without significant surface damage to internal parts, but also allows for in-situ cleaning of the internal components.

[0040] This cleaning method allows the use of internal components with a pyrolytic carbon coating instead of, for example, silicon carbide or tantalum carbide coatings. Depositing a protective pyrolytic carbon layer on the internal components significantly reduces the cost of manufacturing internal components compared to manufacturing internal components that involve depositing silicon carbide or tantalum carbide layers on them.

[0041] Furthermore, the PyC-coated internal components can be reused multiple times for silicon carbide epitaxy, resulting in a long lifespan. This makes this method particularly suitable as an in-situ cleaning approach compared to current technologies. Unlike conventional cleaning methods (such as ClF3-based methods, which erode carbon materials even at low temperatures and may damage uncoated graphite or insulation materials outside the thermal reactor zone), this method utilizes a controlled oxidation temperature that selectively oxidizes the CDC material without eroding graphite or other carbon-based components. This ensures that uncoated materials outside the thermal deposition zone remain unaffected, providing additional benefits for in-situ cleaning applications.

[0042] This cleaning method also provides the ability to regulate the etching of parasitic SiC and the subsequent oxidation of the resulting CDC material. This regulation ensures that the etching or oxidation process proceeds uniformly when the PyC coating is exposed during cleaning, thereby minimizing localized damage to the PyC layer. The ability to control the etching / cleaning process time enables precise removal of the CDC material while maintaining the structural integrity and performance of the PyC coating. This level of control represents an improvement over existing methods that lack this precision, potentially leading to uneven erosion or damage to the protective coating.

[0043] A second aspect of the invention relates to an internal component of an epitaxial process chamber for silicon carbide epitaxial growth, which is suitable for cleaning by a cleaning method according to a first aspect of the invention, the internal component comprising a pyrolytic carbon coating having a highly layered microstructure and comprising less than 5 ppm of impurities, wherein the internal component is configured to undergo the cleaning method, and / or wherein the internal component is cleaned according to the cleaning method.

[0044] A third aspect of the invention relates to an internal component contaminated by parasitic silicon carbide, the internal component being configured to undergo a cleaning method according to a first aspect of the invention, the internal component comprising a pyrolytic carbon coating, wherein the pyrolytic carbon coating has a highly layered microstructure and comprises impurities less than 5 ppm. The internal component may also comprise a diamond-like carbon layer or a glassy carbon layer instead of the pyrolytic carbon layer, or a combination of the above carbon layers.

[0045] A fourth aspect of the invention relates to an epitaxial process system comprising a controller and an epitaxial process chamber, wherein the epitaxial process chamber includes at least one internal component according to a second or third aspect of the invention, and wherein the controller is arranged to operate the epitaxial process chamber in a cleaning mode, wherein parasitic silicon carbide grown on the at least one internal component in the epitaxial process chamber is removed according to a cleaning method according to a first aspect of the invention.

[0046] In this disclosure, "interior" refers to the inner surface of the epitaxial process chamber used for silicon carbide epitaxial growth, and the surface of the internal components of the epitaxial process chamber inside the epitaxial process chamber.

[0047] Unless otherwise stated, the corresponding embodiments disclosed below with respect to the first aspect also apply to the internal components of the epitaxial process chamber according to the invention (second aspect), the internal components contaminated by parasitic silicon carbide growth (third aspect), and the apparatus for cleaning the internal components of the epitaxial process chamber (fourth aspect). Detailed Implementation

[0048] The cleaning method is explained in detail below.

[0049] In this specification, "internal components" refers to components inside the epitaxial process chamber (such as carbon-based components, or more generally carbon-based consumable components) that are exposed to the epitaxial silicon carbide deposition process and are therefore susceptible to the parasitic growth of silicon carbide.

[0050] In this specification, "pyrolytic carbon" refers to the form of carbon produced through a pyrolysis process, which involves heating hydrocarbons to near their decomposition temperature and causing graphite to crystallize. This results in the formation of materials with a highly graphitic structure.

[0051] In this specification, "carbide-derived carbon" (CDC) refers to any form of carbon material produced by selectively removing metal atoms (such as Si or Ti) from a metal carbide (e.g., through a process known as etching or extraction). Typically, metal carbides such as silicon carbide (SiC) or tantalum carbide (TaC) are used as precursors. The selective removal of the metal leaves behind a carbon structure with a porous structure and high surface area.

[0052] In one embodiment, the CDC material, residue, or species may exist in the form of a layer or film. The formed CDC may even appear to resemble a crystalline structure. In step 1a), in addition to forming the CDC material, gaseous metal chlorides or fluorides may also be formed. These are directly removed during step 1a (e.g., an etching step) where the internal components are exposed to a halogen-containing gas.

[0053] In one embodiment, step 2) is performed by placing the CDC material in an oxygen-containing gas at a temperature of 390°C to 700°C, preferably 450°C to 600°C. Step 2) can be performed for 0.5 to 24 hours, preferably 3 to 12 hours, and more preferably 5 to 10 hours. Furthermore, step 2) can be performed every one or two weeks, or immediately when the thickness of the parasitic silicon carbide layer exceeds a predefined thickness (e.g., 300 µm).

[0054] Due to the known high risk of oxidation of PyC coatings, the use of oxygen-containing gases with such conditions is generally not considered. However, the specific PyC coating used in this invention can combine the conditions of step 2) above with those of step 1a) or step 1b) above, and has the effect of more effectively removing parasitic SiC, so that the PyC coating of the internal components remains intact, which significantly extends the life of the internal components.

[0055] In this disclosure, "parasitic silicon carbide" refers to silicon carbide (SiC) deposited on the surface of a non-SiC wafer within the reactor zone, i.e., deposited on the surface of an epitaxial process chamber or an internal component. It may exist in the form of a layer or a (polycrystalline) film, and once said layer or film becomes thick (a few millimeters thick), it may have a shape like a broccoli flower.

[0056] In one embodiment, the oxygen-containing gas may include an oxygen content of up to 100% by volume, such as 15% to 50% by volume, or 18% to 25% by volume. Examples of oxygen-containing gases are air, oxygen-enriched air, (pure) oxygen, mixtures of oxygen with one or more inert gases (such as argon), and nitrogen oxides such as nitrous oxide (N₂O), nitric oxide (NO), nitrogen dioxide (NO₂), and dinitrogen tetroxide (N₂O₄).

[0057] In one embodiment, in step 2), the CDC material can be removed by oxidizing it into carbon monoxide and carbon dioxide.

[0058] In another alternative embodiment, step 2) can be performed by placing the CDC material in a gas containing hydrogen and / or ammonia at a temperature of 500°C to 2300°C, preferably 1000°C to 1500°C.

[0059] In another alternative embodiment, step 2) can be performed by mechanically removing the CDC material from the outer surface of the internal component, such as by mechanical polishing or grinding with a metal or silicon carbide brush, gas purging / sandblasting, shock wave pulse cleaning, laser ablation, or plasma-assisted cleaning.

[0060] In one embodiment, the internal component further includes a graphite core, and the pyrolytic carbon coating is deposited on the graphite core.

[0061] In one embodiment, the internal component is a wafer carrier, also referred to as a substrate carrier, susceptor, susceptor plate, teller, cover segment, half-moon, ring, upper or lower electrode, shower head, liner, wafer lift pin, preheating ring, planetary disk, spindle, spider, ceiling part, or cover segment.

[0062] In one embodiment, step 1a) is performed at a temperature of 500°C to 1450°C, preferably 850°C to 1200°C.

[0063] Step 1a) or step 1b) can be performed for 0.25 to 6 hours, preferably 1 to 4 hours. In addition, step 1a) or step 1b) can be performed once every 1 or 2 weeks, or immediately when the thickness of the parasitic silicon carbide layer exceeds a certain predefined thickness (e.g., 300 µm).

[0064] In one embodiment, argon is used as the inert gas in step 1b).

[0065] In one embodiment, step 1b) is performed at a temperature of 1500°C to 2200°C, preferably 1800°C to 2000°C, and / or at a pressure of 0.0001 mbar to 250 mbar, preferably 0.1 mbar to 100 mbar.

[0066] In one embodiment, step 1a) and / or step 2) are performed at a pressure of 100 mbar to 1200 mbar, preferably 500 mbar to 1100 mbar, more preferably 800 mbar to 1050 mbar.

[0067] In one embodiment, the halogen-containing gas is chlorine, bromine, or a combination of two or more thereof, which can be mixed with nitrogen, argon, helium, or a combination thereof, preferably chlorine or a mixture of chlorine with nitrogen or argon.

[0068] In one embodiment, steps 1a), 1b), and / or 2) are performed in situ or ex-situ.

[0069] In step 2), the CDC material can be removed in various ways. Removing the CDC material by placing it in an oxygen-containing gas or a gas containing hydrogen and / or ammonia can be done either in situ or ex-situ. Removal in step 2) can also be done ex-situ by mechanically removing the CDC material from the outer surface of the internal component, such as by mechanical polishing or grinding with a metal or silicon carbide brush, gas purging / sandblasting, shock wave pulse cleaning, laser ablation, or plasma-assisted cleaning.

[0070] CDC material can be removed from the outer surface of internal components by polishing, milling, turning, and grinding with loose or consolidated gravel. Abrasive blasting (e.g., sandblasting, where any material with a hardness between graphite and CDC can be used instead of sand) can also be used to remove CDC material.

[0071] Alternatively, step 2) can be performed off-site by dry chemical cleaning or wet cleaning, such as by cleaning with steam or chemicals, water jet, liquid blasting or ultrasonic cleaning, or by laser pulse, plasma cleaning, compressed gas purging and plasma-enhanced oxidation using oxygen plasma.

[0072] As an alternative, step 2) can be performed in situ, for example, by removing the CDC material through dry chemistry.

[0073] Since the remaining CDC layer largely retains the same volume and morphology as the original SiC layer, its density is lower compared to the original SiC layer. This results in a relatively soft layer, and therefore, makes it relatively easy to remove the CDC layer manually, mechanically, or by sandblasting.

[0074] The method may also include the following steps:

[0075] 3) Wash and optionally dry the internal components that contain no or substantially no CDC material to obtain internal components with reduced impurities and dust particles. Washing can be performed with a liquid such as deionized water or deionized water. Drying can be performed in air under ambient conditions.

[0076] The internal components of the epitaxial process chamber used for silicon carbide epitaxial growth are particularly suitable for growing silicon carbide epitaxial layers on silicon carbide wafers, silicon substrates, or graphite substrates.

[0077] Alumina (Al2O3) can also be a possible substrate material, but it is less suitable for use as a substrate because chlorides can etch Al2O3 in the presence of carbon.

[0078]

[0079] In one embodiment, the internal component includes a graphite core selected from the group consisting of porous graphite, a graphite matrix, and a carbon matrix containing other phases (such as carbon fibers or particles).

[0080] In one embodiment, the pyrolytic carbon coating is deposited on the internal component using chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0081] In one embodiment, the pyrolytic carbon coating is deposited on the internal component using CVD, wherein a precursor gas containing a carbon source (such as methane or propane) is used, and / or a deposition temperature of 900°C to 2200°C, preferably 1100°C to 2000°C, more preferably 1400°C to 1900°C is used.

[0082] In one embodiment, the pyrolytic carbon coating has a thickness of 3 µm to 70 µm, preferably 5 µm to 50 µm, more preferably 5 µm to 25 µm, and even more preferably 10 µm to 20 µm.

[0083] The method proposed in this paper uses a selective etching process with Cl2, Br2, or a combination thereof, which is very fast (approximately 50 µm / h - 100 µm / h) and does not etch the PyC coating. This method etches the parasitic SiC by removing Si atoms from the SiC lattice, leaving a nanoporous carbon matrix (carbide-derived carbon, CDC).

[0084] In particular, when using selective oxidation methods, porous carbon is oxidized without affecting the PyC coating by limiting the oxidation temperature to a specific range (390°C-700°C, preferably 450°C-600°C). Typically, the oxidation initiation temperature range for PyC coatings is 450°C-700°C, depending on the purity and microstructure of the PyC coating.

[0085] Therefore, oxidation methods for removing CDC from PyC coatings are not considered due to the risks associated with PyC oxidation. Our PyC coatings have a unique microstructure and high purity levels (impurities <5 ppm, preferably <1 ppm), allowing selective oxidation to be well implemented, oxidizing only CDC without affecting the PyC coating. This combination of "selective etching" and "selective oxidation" is a novel method for removing parasitic SiC from fragile PyC-coated graphite components. Attached Figure Description

[0086] The invention is described below with reference to the accompanying drawings, in which embodiments are shown, and where like reference numerals indicate like or similar elements. The invention is by no means limited to the embodiments disclosed herein.

[0087] Figure 1 A cleaning method for removing parasitic silicon carbide from internal components is shown;

[0088] Figure 2 An internal component including a pyrolytic carbon coating is shown;

[0089] Figure 3 A cross-sectional view of an internal component including a pyrolytic carbon coating is shown;

[0090] Figure 4 An internal component including a pyrolytic carbon coating on which a silicon carbide layer is deposited; is shown.

[0091] Figure 5 An internal component comprising a pyrolytic carbon coating has been shown, which has undergone two repeated cycles of silicon carbide deposition, etching, and oxidation.

[0092] Figure 6A A cross-sectional view (PyC-A) of an internal component including a pyrolytic carbon coating according to the present invention is shown.

[0093] Figure 6B A cross-sectional view (PyC-B) of an internal component including a pyrolytic carbon coating, not according to the invention, is shown.

[0094] Figure 7 The Raman spectra of the PyC-A and PyC-B coatings are shown. Detailed Implementation

[0095] Figure 1 A flowchart is shown of a cleaning method 1 for removing parasitic silicon carbide 101 from an internal component 103 of an epitaxial process chamber for silicon carbide epitaxial growth. The cleaning method 1 may include a first step 1a): placing (3a) the internal component 103 in a halogen-containing gas, namely chlorine, bromine, or a combination of two or more thereof, at a temperature of 150°C to 1700°C, preferably 390°C to 700°C, more preferably 450°C to 600°C, to convert the parasitic silicon carbide 101 present on the internal component into carbide-derived carbon (CDC) material 107.

[0096] As an alternative to step 1a), the cleaning method 1 may include a first step 1b): at a temperature of 1200°C to 2400°C and at 1×10 -10 At a pressure of millibar to 500 millibar, the internal component 103 is placed in an inert gas (such as argon) to convert the parasitic silicon carbide 101 present on the internal component into CDC material 107.

[0097] The second step is to remove (5) the CDC material 107 formed in the placement (3a, 3b) steps from the internal component 103 to obtain the outer surface 109 of the internal component 103 which contains no or substantially no CDC material 107.

[0098] Figure 2 An internal component 103 for an epitaxial process chamber used for silicon carbide epitaxial growth is shown. This internal component 103 includes a graphite substrate 101 coated with a pyrolytic carbon (PyC) layer 105. The PyC 105 has a highly layered microstructure and contains less than 5 ppm of impurities, preferably less than 1 ppm, which is deposited onto the graphite substrate 101 via a high-temperature vapor deposition process. The internal component 103 is arranged to undergo silicon carbide (SiC) deposition.

[0099] Figure 3 A cross-sectional view of an internal component 103, including a graphite plate 111 and coated with a PyC layer 105, is shown. The PyC layer 105 on top of the graphite plate 111 or graphite core is clearly shown in the scanning electron microscope (SEM) image, and it has an average thickness of approximately 7 µm to 8 µm. The outer surface 109 of the internal component 103 is free of CDC material 107. Furthermore, the highly layered microstructure of the PyC coating is clearly visible.

[0100] Figure 4An internal component 103 comprising a graphite core 111 and a PyC coating 105 is shown. Parasitic silicon carbide 101 exists as a silicon carbide coating with a thickness of approximately 100 µm on the surface of the internal component 103. The parasitic silicon carbide coating 101 is deposited onto a graphite plate 111 coated with pyrolytic carbon 105 using high-temperature chemical vapor deposition.

[0101] Figure 5 An internal component 103 comprising a graphite plate 111 and a PyC coating 105 is shown. The internal component 103 has undergone two cycles of repeated SiC deposition, placing the internal component 103 coated with deposited SiC 101 (i.e. parasitic SiC) in a halogen-containing gas 3a to convert the parasitic SiC 101 into CDC material 107, and removing the CDC material 107 from the internal component 103 to obtain an internal component 103 as a graphite plate 111 coated with PyC 105 having an outer surface 109 substantially free of CDC material 107.

[0102] Figure 6A and Figure 6B The comparison results of the structure of PyC coating 105 are shown in the figure. Figure 6A The diagram shows a cross-sectional view (PyC-A) of a portion of an internal component 103 (which is a graphite substrate) including a pyrolytic carbon coating 105 according to the present invention. The highly layered microstructure of PyC-A 105 is shown by the clearly visible individual layers that can be distinguished from each other in the SEM image. The highly layered microstructure is shown in the diagram. Figure 6B The PyC-B coating on the graphite substrate is almost non-existent, and it clearly has a structure more similar to a monolithic structure.

[0103] Figure 7 The Raman spectra of PyC-A coating 105 and PyC-B coating are shown in the figure. Figure 7 It was shown at 450 cm -1 Up to 3500cm -1The peak intensity (I) is within the wavenumber (λ) range. The G-band corresponds to the in-plane vibrations of sp²-bonded carbon atoms and is associated with the stretching of CC bonds. It is characteristic of graphite materials and indicates the presence of ordered graphitic domains. High intensity indicates the presence of abundant graphitic (sp²) carbon. A wider G-band can indicate the presence of strain or defects within the graphite structure. The D-band is associated with the breathing mode of sp² carbon rings and requires defects or edges to be activated. The D-band originates from a double resonance process involving interval scattering of phonons near the K point in the Brillouin zone. Therefore, the D-band is associated with the presence of defects and disorder in the carbon structure and is referred to as the "disorder" band. Higher intensity D-bands indicate more defects (structural defects, such as disruptions in sp²-bonded carbon networks) and a higher degree of disorder in the material. Table 1 provides the peak positions of the G-band and D-band for each PyC coating.

[0104] Table 1. Peak positions of coatings PyC-A and PyC-B.

[0105]

[0106] The G-band / D-band peak intensity ratio is an indicator of the rate of in-plane ordering of carbon atoms in the microstructure of graphite (substrate 111). From... Figure 7 It is clear that the G-band / D-band ratio of PyC-A is much higher than that of PyC-B, which indicates that the in-plane ordering of carbon atoms in the microstructure of the graphite substrate of PyC-A is better.

[0107] Modifications and additions to the embodiments disclosed above will be apparent to those skilled in the art and are covered within the scope of the appended claims. The embodiments and examples of the first aspect of the invention are also applicable to the second, third, and fourth aspects of the invention.

[0108] Those skilled in the art, by studying the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are stated in dissimilar dependent claims does not indicate that combinations of these measures cannot be advantageously used. Any reference numerals in the claims should not be construed as limiting their scope. One or more objects of the invention are achieved by the appended claims.

[0109] Example

[0110] Oxidation experiments were conducted to demonstrate the oxidation rates of different types of carbon materials. Table 2 shows the oxidation rates of two different PyC coatings (i.e., PyC-A and PyC-B as disclosed above), as well as the oxidation rates of graphite and CDC materials.

[0111] Table 2. Isothermal oxidation rates of different carbon materials in air.

[0112]

[0113] The 55 µm CDC layer cracked and peeled off from the graphite substrate after being oxidized at 600°C for 30 minutes.

[0114] The oxidation of the PyC-B coating was tested at 450°C.

[0115] Oxidation of the PyC-B coating at 600°C was not tested.

[0116] These results indicate that the PyC-A coating, with its highly layered microstructure, exhibits significantly better oxidation resistance compared to the PyC-B coating, at least under oxidizing conditions where the CDC material is oxidized.

[0117] High oxidation temperatures are preferred for effectively removing CDC material without damaging the PyC coating using selective oxidation methods. However, some PyC coatings (such as PyC-B coatings) will inevitably be oxidized when CDC carbon is oxidized. Therefore, PyC-A coatings are more suitable for this purpose than PyC-B coatings. In this invention, PyC coatings with a highly layered microstructure (such as...) Figure 6A The PyC-A shown is much more advantageous for cleaning internal components by cleaning method 1 according to the invention. This allows us to remove CDC material from the surface of graphite components coated with PyC through a selective oxidation process in a temperature range of 390°C-700°C, preferably 450°C-600°C.

[0118] Therefore, oxidation methods for removing CDC material from PyC coatings are not considered due to the risks associated with PyC oxidation. The PyC coating according to the invention has a unique, highly layered microstructure and high purity level (impurities <5 ppm, preferably <1 ppm), allowing selective oxidation to be well implemented, oxidizing only the CDC material without affecting the PyC coating. This combination of "selective etching" and "selective oxidation" is a novel method for removing parasitic SiC from fragile PyC-coated internal components.

[0119] Terms and Conditions

[0120] 1. A cleaning method for removing parasitic silicon carbide from an internal component of an epitaxial process chamber for silicon carbide epitaxial growth, the internal component comprising a pyrolytic carbon coating, the method comprising the steps of:

[0121] 1a) The internal component is placed in a halogen-containing gas at a temperature of 150°C to 1700°C to convert the parasitic silicon carbide present on the internal component into carbide-derived carbon (CDC) material, wherein the halogen-containing gas does not consist of chlorine trifluoride or fluorine gas, nor does it contain chlorine trifluoride or fluorine gas, or

[0122] 1b) At a temperature of 1000°C (preferably 1200°C) to 2400°C and at 1×10 -10 Under pressures ranging from millibar to 500 millibar, the internal components are placed in an inert gas to convert the parasitic silicon carbide present on the internal components into the CDC material.

[0123] 2) Remove the CDC material from the internal component to obtain an outer surface of the internal component that contains no or substantially no CDC material.

[0124] 2. The cleaning method according to Clause 1, wherein step 2) is performed by placing the CDC material in an oxygen-containing gas at a temperature of 390°C to 670°C, preferably 450°C to 600°C.

[0125] 3. The cleaning method according to Clause 1, wherein step 2) is performed by placing the CDC material in a gas containing hydrogen and / or ammonia at a temperature of 500°C to 2300°C, preferably 1000°C to 1500°C.

[0126] 4. The cleaning method according to Clause 1, wherein step 2) is performed by mechanically removing the CDC material from the outer surface of the internal component, for example by mechanical polishing or grinding with a metal or silicon carbide brush, gas purging / sandblasting, shock wave pulse cleaning, laser ablation, or plasma-assisted cleaning.

[0127] 5. The cleaning method according to any one of the preceding clauses, wherein the internal component further includes a graphite core, and the pyrolytic carbon coating is deposited on the graphite core.

[0128] 6. The cleaning method according to any one of the preceding clauses, wherein the internal component is a wafer carrier, also known as a substrate carrier, base, base disk, tray, cover section, crescent, ring, upper or lower electrode, spray head, liner, wafer top lifting pin, preheating ring, planetary disk, spindle, support, top component or cover section.

[0129] 7. The cleaning method according to any one of the preceding clauses, wherein step 1a) is performed at a temperature of 500°C to 1450°C, preferably 850°C to 1200°C.

[0130] 8. The cleaning method according to any one of the preceding clauses, wherein step 1b) is performed at a temperature of 1500°C to 2200°C, preferably 1800°C to 2000°C and / or at a pressure of 0.001 mbar to 250 mbar, preferably 0.1 mbar to 100 mbar.

[0131] 9. The cleaning method according to any one of the preceding clauses, wherein step 1a) and / or step 2) is performed at a pressure of 100 mbar to 1200 mbar, preferably 500 mbar to 1100 mbar, more preferably 800 mbar to 1050 mbar.

[0132] 10. The cleaning method according to any one of the preceding clauses, wherein the halogen-containing gas is chlorine, bromine, or a combination of two or more thereof, which may be mixed with nitrogen, argon, helium, or a combination thereof, preferably chlorine or a mixture of chlorine with nitrogen or argon.

[0133] 11. The cleaning method according to any one of the preceding clauses, wherein step 1a), step 1b) and / or step 2) are performed in situ or ex-situ.

[0134] 12. An internal component of an epitaxial process chamber for silicon carbide epitaxial growth, adapted to be cleaned by a cleaning method according to any one of the preceding clauses, the internal component comprising a pyrolytic carbon coating, wherein the internal component is arranged to undergo the cleaning method, and / or wherein the internal component is cleaned according to the cleaning method; and / or an internal component contaminated by parasitic silicon carbide growth and configured to undergo the cleaning method.

[0135] 13. The internal component as described in Clause 12, wherein the internal component includes a graphite core selected from the group consisting of porous graphite, a graphite matrix, and a carbon matrix containing other phases (such as carbon fibers or particles).

[0136] 14. The internal component as described in Clause 12 or 13, wherein the pyrolytic carbon coating is deposited on the internal component using chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0137] 15. An internal component according to any one of clauses 12 to 14, wherein the pyrolytic carbon coating is deposited on the internal component using CVD, and wherein a precursor gas containing a carbon source (such as methane or propane) is used, and / or a deposition temperature of 900°C to 2200°C, preferably 1100°C to 2000°C, more preferably 1400°C to 1900°C is used.

[0138] 16. The internal component according to any one of clauses 12 to 15, wherein the pyrolytic carbon coating has a thickness of 3 µm to 70 µm, preferably 5 µm to 50 µm, more preferably 8 µm to 25 µm, and even more preferably 10 µm to 20 µm.

[0139] 17. An epitaxial process system comprising a controller and an epitaxial process chamber, wherein the epitaxial process chamber includes at least one internal component according to any one of clauses 12 to 16, and wherein the controller is arranged to operate the epitaxial process chamber in a cleaning mode, wherein a cleaning method according to any one of clauses 1 to 11 removes parasitic silicon carbide grown on the at least one internal component in the epitaxial process chamber.

Claims

1. A cleaning method (1) for removing parasitic silicon carbide (101) from an internal component (103) of an epitaxial process chamber for silicon carbide epitaxial growth, said internal component comprising a pyrolytic carbon coating (105), wherein, The pyrolytic carbon coating (105) has a highly layered microstructure and contains less than 5 ppm of impurities. The method (1) includes the following steps: 1a) The internal component is placed in a halogen-containing gas (3a) at a temperature of 150°C to 1700°C to convert the parasitic silicon carbide (101) present on the internal component (103) into a carbide-derived carbon (CDC) material (107), wherein the halogen-containing gas is chlorine, bromine, or a combination of two or more thereof that can be mixed with nitrogen, argon, helium, or a combination thereof, or 1b) At temperatures between 1000°C and 2400°C and within 1×10 -10 Under pressures ranging from millibar to 500 millibars, the internal component (103) is placed in an inert gas (3b) to convert the parasitic silicon carbide (101) present on the internal component (103) into the CDC material (107); and 2) Remove (5) the CDC material (107) from the internal component (103) to obtain an outer surface (109) of the internal component (103) that is free of or substantially free of the CDC material (107).

2. The cleaning method (1) according to claim 1, wherein, Step 2) is performed by placing the CDC material (107) in an oxygen-containing gas at a temperature of 390°C to 700°C, preferably 450°C to 600°C.

3. The cleaning method (1) according to claim 1, wherein, Step 2) is performed by placing the CDC material (107) in a hydrogen and / or ammonia gas at a temperature of 500°C to 2300°C, preferably 1000°C to 1500°C.

4. The cleaning method (1) according to claim 1, wherein, Step 2) is performed by mechanically removing the CDC material (107) from the outer surface (109) of the internal component (103), for example by mechanical polishing or grinding with a metal or silicon carbide brush, gas purging / sandblasting, shock wave pulse cleaning, laser ablation or plasma-assisted cleaning.

5. The cleaning method (1) according to any one of the preceding claims, wherein, The internal component (103) also includes a graphite core (111), and the pyrolytic carbon coating (105) is deposited on the graphite core (111).

6. The cleaning method (1) according to any one of the preceding claims, wherein, The internal component (103) is a wafer carrier, also known as a substrate carrier, base, base disk, tray, cover section, crescent, ring, upper or lower electrode, spray head, lining, wafer top lifting pin, preheating ring, planetary disk, spindle, support, top component or cover section.

7. The cleaning method (1) according to any one of the preceding claims, wherein, Step 1a) is performed at a temperature of 500°C to 1450°C, preferably 850°C to 1200°C.

8. The cleaning method (1) according to any one of the preceding claims, wherein, Step 1b) is performed at a temperature of 1500°C to 2200°C, preferably 1800°C to 2000°C, and / or at a pressure of 0.001 mbar to 250 mbar, preferably 0.1 mbar to 100 mbar.

9. The cleaning method (1) according to any one of the preceding claims, wherein, Step 1a) and / or step 2) are performed at a pressure of 100 mbar to 1200 mbar, preferably 500 mbar to 1100 mbar, more preferably 800 mbar to 1050 mbar.

10. The cleaning method (1) according to any one of the preceding claims, wherein, The halogen-containing gas is chlorine, bromine, or a combination of two or more of them that can be mixed with nitrogen, argon, helium, or a combination thereof, preferably chlorine or a mixture of chlorine with nitrogen or argon.

11. The cleaning method (1) according to any one of the preceding claims, wherein, Step 1a), step 1b), and / or step 2) are performed in situ or in anatomical locations.

12. An internal component (103) of an epitaxial process chamber for epitaxial growth of silicon carbide (101), adapted to be cleaned by the cleaning method (1) according to any one of the preceding claims, said internal component (103) comprising a pyrolytic carbon coating (105), wherein, The pyrolytic carbon coating (105) has a highly layered microstructure and includes less than 5 ppm of impurities, wherein the internal component (103) is configured to undergo the cleaning method (1), and / or wherein the internal component (103) is cleaned according to the cleaning method (1).

13. An internal component (103) contaminated by parasitic silicon carbide (101), configured to undergo a cleaning method (1) according to any one of claims 1 to 11, said internal component (103) comprising a pyrolytic carbon coating (105), wherein, The pyrolytic carbon coating (105) has a highly layered microstructure and contains less than 5 ppm of impurities.

14. The internal component (103) according to claim 12 or 13, wherein, The internal component (103) includes a graphite core (111), which is selected from the group consisting of porous graphite, graphite matrix, and carbon matrix containing other phases such as carbon fibers or particles.

15. The internal component (103) according to any one of claims 12 to 14, wherein, The pyrolytic carbon coating (105) is deposited on the internal component (103) using chemical vapor deposition (CVD) or physical vapor deposition (PVD).

16. The internal component (103) according to any one of claims 12 to 15, wherein, The pyrolytic carbon coating (105) is deposited on the internal component (103) using CVD, wherein a precursor gas containing a carbon source such as methane or propane is used, and / or a deposition temperature of 900°C to 2200°C, preferably 1100°C to 2000°C, more preferably 1400°C to 1900°C is used.

17. The internal component (103) according to any one of claims 12 to 16, wherein, The pyrolytic carbon coating (105) has a thickness of 3 µm to 70 µm, preferably 5 µm to 50 µm, more preferably 8 µm to 25 µm, and even more preferably 10 µm to 20 µm.

18. An epitaxial process system, comprising a controller and an epitaxial process chamber, wherein, The epitaxial process chamber includes at least one internal component (103) according to any one of claims 12 to 17, and wherein the controller is configured to operate the epitaxial process chamber in a cleaning mode, wherein parasitic silicon carbide (101) on at least one internal component (103) in the epitaxial process chamber is removed by a cleaning method (1) according to any one of claims 1 to 11.

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