Etching silicon carbide buildup from reactor components

Abstract

The invention relates to a method of etching silicon carbide build-up from one or more workpieces of a reaction chamber for depositing a silicon carbide layer on a substrate. The method comprises the steps of: (i) providing a silicon carbide build-up on one or more workpieces of a reaction chamber of a reactor for depositing silicon carbide; (ii) performing at least one cycle of an etching process; (iii) performing at least one cycle of a chemical vapor deposition process. The invention also relates to a reactor adapted to perform said method.

Description

Technical Field

[0001] This invention relates to the field of epitaxial deposition of semiconductor films on substrates; in particular, it relates to a method and reactor suitable for performing silicon carbide chemical etching from reactor components. Background Technology

[0002] During the epitaxial deposition process, one or more single-crystal semiconductor layers are grown in a controlled manner on one or more rotating substrates placed in the reaction chamber of a reactor. However, during this process, undesirable semiconductor deposits may also grow on other parts of the reaction chamber exposed to process gases.

[0003] For example, during the epitaxial deposition of single-crystal silicon carbide on a substrate, such as during the epitaxial deposition of 3C, 4H, or 6H silicon carbide polymorphs, users typically observe uncontrolled silicon carbide build-ups on multiple structural and functional components of the reaction chamber. It should be noted that due to the hardness of the material, these undesirable silicon carbide build-ups are difficult to remove, and conventional techniques used in the silicon semiconductor industry are not suitable for silicon carbide removal.

[0004] In contrast to ordered monocrystalline layers deposited on a substrate, silicon carbide accumulations typically comprise polycrystalline and / or amorphous forms of silicon carbide. Generally, it is a mixture of polycrystalline and amorphous silicon carbide. As can be observed in XRD measurements, the latter can constitute up to 20-60% of the total, although the relative ratio of the two forms can vary considerably locally and / or on average.

[0005] The parasitic phenomenon described above is particularly relevant in hot-wall reactors, where it generally affects the upstream end of the chamber (i.e., where the precursor gas enters the reaction chamber) and the elements surrounding or in contact with the substrate.

[0006] It should be noted that undesirable SiC accumulation occurs not only on the exposed surfaces of the reaction chamber, but also on those components that have been preventively coated.

[0007] In practice, graphite chamber components coated with a TaC layer can be obtained to protect the graphite surface during cleaning operations. Alternatively, a thin SiC coating can be used to seal the exposed porous graphite surface to prevent contamination. In this case, the SiC coating used on the graphite component is in a polycrystalline form with a smooth outer surface, characterized by a surface roughness of less than 6.3 μm Ra, more typically less than 1 μm Ra.

[0008] It has been observed that parasitic deposition of SiC on reaction chamber components typically leads to the rapid growth of cauliflower-like, porous, dendritic structures, which ultimately affects the quality of the deposited layer on the semiconductor substrate. These parasitic deposits have an uneven appearance with visible wrinkles.

[0009] To prevent parasitic films from negatively impacting the deposition process, the reaction chamber undergoes frequent preventative maintenance (PM) operations, such as after the growth of a total epitaxial layer of 100 μm to 2000 μm.

[0010] During PM, the machine is cooled and purged, and some or all of the affected parts are manually removed from the room for mechanical cleaning, disposal, and / or replacement.

[0011] PM operation negatively impacts reactor productivity, thus severely affecting the economics of the epitaxial deposition process. In fact, PM operation can lead to reactor downtime of several hours, occurring multiple times per week or month.

[0012] In Si reactors, in-situ or ex-situ chemical etching processes are known and used to remove unwanted Si parasitic deposits. These methods allow for more reproducible results than their mechanical cleaning counterparts. Furthermore, in-situ etching processes can be performed without opening and entering the reaction chamber, advantageously reducing reactor downtime and simplifying operation.

[0013] However, compared to silicon, silicon carbide exhibits very different chemical and physical properties. It is a harder material, making it difficult to erode by chemical methods without ultimately damaging the associated reactor components and / or introducing potential contaminants into the chamber.

[0014] It should be noted that in-situ etching is typically performed using chemicals that react with parasitic deposition, resulting in gaseous byproducts. In the case of silicon carbide, this process may result in solid powdery byproducts.

[0015] Without significantly extending the etching time, powdery byproducts from the etching process may be difficult to remove, which could ultimately damage the chamber components below and affect reactor downtime.

[0016] While methods for etching SiC have been disclosed in the art, these methods typically discuss the removal of several top layers of ordered SiC from a bulk SiC wafer, as described in, for example, US20140030892A1 and US20060001028A1. In these cases, the chemical etching of SiC is performed without any underlying (potentially different in composition) portions that could be damaged during the process. These processes typically remove only a few micrometers of SiC to reduce warpage of the single-crystal SiC substrate and surface cracking of the SiC substrate holder, respectively. These methods do not address the problem of removing disordered parasitic SiC deposits without damaging the affected reaction chamber components.

[0017] Therefore, it is desirable to provide a new method for etching polycrystalline-amorphous SiC parasitic deposits from relevant components of the reaction chamber without damaging the components.

[0018] It is also desirable to provide a method for etching parasitic accumulations of polycrystalline / amorphous SiC that can be carried out in situ, i.e., directly in the reaction chamber, without opening the reaction chamber and / or removing it from the reactor.

[0019] It is also desirable to provide a method for in-situ etching of parasitic accumulations in polycrystalline / amorphous SiC to prevent powdery byproducts of the etching process from adversely affecting subsequent deposition processes.

[0020] Furthermore, it is desirable to provide a new reactor suitable for performing the above-described method. Additionally, it is desirable to provide a reactor configured to perform the method in an automated manner. Summary of the Invention

[0021] This synopsis is provided to introduce some concepts in a simplified form. These concepts are further described in detail in the following detailed description of exemplary embodiments of this disclosure. This synopsis is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0022] The purpose of this invention is to overcome the shortcomings of the prior art.

[0023] In particular, the object of the present invention is to provide a method for etching silicon carbide deposits from one or more workpieces in a reactor chamber for depositing a silicon carbide layer on a substrate, the method comprising the steps of:

[0024] (i) Providing a silicon carbide deposit on one or more workpieces, wherein the silicon carbide deposit comprises silicon carbide in polycrystalline and / or amorphous forms;

[0025] (ii) Perform at least one cycle of the etching process, including the following steps:

[0026] A1. Raise the temperature of the reaction chamber to 800-1450°C;

[0027] A2. Increase the pressure in the reaction chamber to 100-700 mbar;

[0028] B. The reactive composition is delivered into a reaction chamber; the reactive composition comprises at least a first reactive gas and an inert gas;

[0029] (iii) Performing at least one cycle of a chemical vapor deposition process in a reaction chamber, including the following steps:

[0030] D. Depositing a ceramic coating onto one or more workpieces;

[0031] In step B, the carrier gas is an inert gas; and the first reactive gas is an inorganic chlorine-containing substance; and the molar concentration of the first reactive gas in the carrier gas is preferably 15-40%.

[0032] Another object of the present invention is to provide a reactor for depositing a silicon carbide layer on a substrate, comprising:

[0033] - At least one reaction chamber, which includes a gas delivery system, the gas delivery system including at least one gas inlet and at least one gas outlet;

[0034] - A heating system suitable for heating the reaction chamber to temperatures up to 1700°C, particularly 800-1450°C;

[0035] - A vacuum system suitable for bringing the reaction chamber to a pressure of 1000 mbar or lower, preferably between 100 and 1000 mbar;

[0036] The reactor is configured to perform the method according to any one of the preceding claims; and at least one gas inlet is connected to or can be connected to a source of a first reactive gas and is connected to or can be connected to a source of a carrier gas; and at least one gas outlet is configured to discharge the gaseous byproducts of steps (ii) and (iii).

[0037] The principal objective described above is achieved by the invention as set forth in the appended claims, which form part of this specification.

[0038] Note that the use of reference numerals in the claims does not limit their scope. The sole purpose of reference numerals is to make the claims easier to understand. Attached Figure Description

[0039] The illustrations presented herein are not intended to be actual views of any particular material, structure, or device, but are merely idealized representations used to describe embodiments of this disclosure.

[0040] Figure 1 This is a block diagram schematically illustrating a method according to an embodiment of the present invention.

[0041] Figure 2 This is a block diagram schematically illustrating another embodiment of the method of the present invention.

[0042] Figure 3 This is a block diagram schematically illustrating another embodiment of the method of the present invention.

[0043] Figure 4 This is a block diagram schematically illustrating another embodiment of the method of the present invention.

[0044] Figure 5 It is shown schematically. Figure 4 A detailed flowchart of the method.

[0045] Figure 6 This is a block diagram schematically illustrating another embodiment of the method of the present invention.

[0046] Figure 7 A longitudinal view of a reaction chamber according to an embodiment of the present invention is shown schematically.

[0047] Figure 8 A schematic transverse view of a reaction chamber according to an embodiment of the present invention is shown.

[0048] Figure 9 A simplified scheme for reactor layout according to an embodiment of the present invention is provided.

[0049] Figure 10 A grayscale image of the parasitic silicon carbide deposited on the spare parts in the reaction chamber is provided. Detailed Implementation

[0050] Although certain embodiments and examples are disclosed below, those skilled in the art will understand that the invention extends beyond the specific embodiments and / or uses disclosed herein, as well as their obvious modifications and equivalents. Therefore, it is intended that the scope of the disclosed invention should not be limited to the specific embodiments described below.

[0051] Reference will now be made to the accompanying drawings, wherein the same reference numerals identify similar structural features or aspects of this disclosure.

[0052] It should be understood that the elements in the accompanying drawings are shown for simplicity and clarity. In particular, some elements may have been omitted or may not be drawn to scale. For example, the dimensions of some elements in the figures may be exaggerated relative to other elements to aid in understanding the embodiments shown in this disclosure.

[0053] In a first aspect, the present invention relates to a method 1 for etching a silicon carbide deposit from one or more workpieces in a reactor chamber suitable for depositing a silicon carbide layer on a substrate, such as... Figure 1 and Figure 2 As shown.

[0054] The method includes steps (i)-(iii) listed below.

[0055] Step (i) includes providing a silicon carbide stack 121 (box 10) on one or more workpieces 120, wherein the silicon carbide stack comprises silicon carbide in polycrystalline and / or amorphous forms.

[0056] Step (ii) includes performing at least one cycle of the etching process (box 30).

[0057] The etching process includes the following steps:

[0058] A1. Raise the temperature of the reaction chamber to 800-1000°C or 1000-1450°C (box 41), including the extreme values;

[0059] A2. Increase the pressure in the reaction chamber to 100-150 mbar or 150-700 mbar (box 42);

[0060] B. The reactive composition is delivered into the reaction chamber (box 50).

[0061] The reactive composition contains one or more reactive gases, i.e. gases suitable for reacting with Si and / or C for etching purposes.

[0062] Specifically, the reactive composition comprises at least a first reactive gas and a carrier gas, wherein the carrier gas is an inert gas, and the first reactive gas is an inorganic chlorine-containing substance. For example, the inert gas may be nitrogen, or preferably helium or argon, to avoid contaminating the chamber.

[0063] The first reactive gas reacts with silicon carbide to produce byproducts, which can be in gaseous and / or particulate form.

[0064] Carrier gas can be advantageously used to adjust and control the concentration and distribution of reactive gases in a chamber.

[0065] Preferably, the molar concentration of the first reactive gas in the carrier gas is 15–40%.

[0066] Step (iii) includes performing at least one cycle (box 35) of a chemical vapor deposition (CVD) process in a reaction chamber, which includes the following steps:

[0067] D. Depositing a ceramic capping layer onto one or more workpieces (box 36), wherein the capping layer is adapted to incorporate byproducts of the etching process in particulate form.

[0068] The “CVD process” performed in step (iii) will be referred to as the “particle trapping process” or “trapping process” to distinguish it from the nominal deposition process of depositing a SiC layer on the substrate, for which the reaction chamber is primarily conceived and operated. This “nominal deposition process” can be, for example, a CVD process or an epitaxial process, but it typically requires different process conditions (in terms of temperature, pressure, runtime, and / or precursors) than the “trapping process.”

[0069] The “capture process” is used for different purposes and achieves different effects than the “nominal deposition process.” In particular, the “capture process” provides a coating containing powder and particles on one or more workpieces in a reaction chamber.

[0070] The inventors have observed that, under the aforementioned temperature and pressure conditions, parasitic SiC deposits can be removed without damaging the associated coated / uncoated graphite components by using a molar concentration of 15-40% of the first reactive gas in the carrier gas. Removal of the parasitic SiC deposits does not necessarily occur before 100% removal is achieved. Advantageously, the deposits can be removed to a degree suitable for regenerating sufficient operating conditions within the reaction chamber, thereby extending the operating time between PM operations.

[0071] "Etching process" refers to the process of chemically removing silicon carbide deposits from a workpiece.

[0072] The etching process can remove SiC deposits by generating volatile chloride-based reaction products that evaporate from the workpiece surface. It should be noted that during etching, inorganic chloride-containing substances react with the silicon carbide deposits, producing byproducts that can be in gaseous and / or particulate form.

[0073] Inorganic chlorine-containing substances may include HCl, Cl2, ClF3 or CCl4 or be composed of them.

[0074] For example, when the inorganic chlorine-containing substance is Cl2, under the pressure and temperature conditions inside the reaction chamber of the etching process, the etching process can be represented as: SiC + 4Cl2 → SiCl4 + CCl4.

[0075] Therefore, Cl2 forms chlorine radicals, which erode SiC deposits without excessively damaging the workpiece.

[0076] In this case, Cl2 with a purity of 99.990% or greater, or even more preferably 99.998%, can be selected.

[0077] Gaseous byproducts from the etching process can exit the reaction chamber through a dedicated outlet, which can also be used to discharge waste gases and / or unreacted gases from the etching process and any other processes optionally carried out in the chamber (such as deposition, cooling, and purging processes).

[0078] However, other reactions may occur during the etching process, resulting in the formation of particulate byproducts that are not discharged through the outlet along with the gaseous byproducts.

[0079] "Particulate byproducts" refers to solid powdery residues with variable particle size and composition.

[0080] These solid byproducts can interfere with subsequent nominal deposition processes.

[0081] They can be removed by performing additional cycles of the etching process, or by using more aggressive etching conditions and / or reactive gases, but this may damage the reaction chamber components.

[0082] Depositing a ceramic coating onto the reaction chamber components (workpieces) allows for the resolution of the aforementioned problems without damaging these components and without interfering with subsequent nominal deposition processes carried out in the reaction chamber.

[0083] For the avoidance of ambiguity, in the preceding and following text, "capping layer" refers to a ceramic coating formed onto workpiece 120 by CVD, wherein the capping layer is suitable for embedding solid byproducts of the etching process to prevent them from contaminating the reaction chamber during further deposition.

[0084] "Etching" refers to chemical etching, which is a process used to chemically clean / remove parasitic deposits of SiC.

[0085] "Workpiece" refers to a reaction chamber component having at least one surface exposed to the process gas.

[0086] During the (nominal) deposition process of the SiC layer on the rotating substrate, the “silicon carbide stack” mentioned herein is directly or can be obtained as a parasitic deposition of SiC on the reaction chamber component (i.e. the workpiece).

[0087] The resulting “silicon carbide stack” contains silicon carbide in polycrystalline and / or amorphous forms.

[0088] Unless otherwise stated, the term “silicon carbide stack” should be considered equivalent to “parasitic SiC stack,” “SiC film,” or “parasitic SiC deposit.”

[0089] Furthermore, the term "film" in the above description should not imply a two-dimensional, regular, and / or ordered geometry. Rather, it refers to a non-uniform SiC coating formed on one or more surfaces of the affected component in the reaction chamber, exhibiting a three-dimensional structure, or a rough, gravelly surface, such as... Figure 10 As shown.

[0090] Figure 10 An image of a parasitic SiC deposit 121 on a workpiece 120 of the reaction chamber, located on the bottom wall of the reaction chamber, is shown. The workpiece is the upstream cap, surrounding the area for receiving a 6” substrate. The parasitic SiC deposit appears lighter in color in the grayscale image compared to the other visible parts of the reaction chamber, which are made of graphite. The silicon carbide deposit 121 is coated with a non-uniform, granular, and gravelly film onto the surface of the workpiece 120 exposed to the precursor gas.

[0091] The more the reaction chamber is exposed to the precursor gas flow, the more pronounced these irregular features of the parasitic membrane become.

[0092] The terms “stacking” and “layer” are used here and below to distinguish, respectively, undesirable parasitic SiC “films” from desired controlled SiC “layers” deposited on the substrate during the nominal deposition process.

[0093] This method is not limited by the specific solid-state properties of silicon carbide stacks. The latter typically comprise or consist of a mixture of both polycrystalline SiC and amorphous SiC, such as a mixture of polycrystalline SiC and 20–60% amorphous SiC. The amount of amorphous SiC in the film can undergo significant local and absolute variations.

[0094] On the other hand, the SiC layers deposited on the substrate are typically single-crystal. They are typically, but not exclusively, polymorphs of 3C, 4H, or 6H SiC.

[0095] Parasitic SiC deposits are a well-known undesirable byproduct of SiC layer deposition.

[0096] Parasitic SiC deposits appear on the surfaces of all parts of the reaction chamber exposed to the SiC precursor gas flow, especially at the upstream end of the reaction chamber (i.e., where the precursor gas enters the reaction chamber) and on components near or in contact with the substrate.

[0097] In particular, parasitic deposition occurs on removable and stationary workpieces (caps, rings, walls), whether stationary or rotating, as a result of their exposure to SiC precursor gases during the nominal deposition process. These workpieces are typically made of materials with much lower hardness than silicon carbide, such as graphite.

[0098] Advantageously, the capping layer can embed particulate byproducts within its solid structure and can prevent them from contaminating and / or interfering with subsequent nominal deposition processes in the reaction chamber.

[0099] Advantageously, steps (i), (ii) and (iii) above can be carried out directly in the reaction chamber, which is located inside the reactor, greatly improving PM time.

[0100] It should be noted that the workpiece forms part and component of the reaction chamber of the reactor used to deposit a silicon carbide layer on the substrate. The method disclosed herein allows for an in-situ etching process followed by in-situ deposition of a ceramic capping layer adapted to embed solid byproducts of the etching process to prevent them from contaminating the reaction chamber during further deposition.

[0101] Therefore, the workpiece does not leave the reaction chamber during the execution of this method, which can significantly and positively impact preventative maintenance time.

[0102] In one embodiment, during step A1, the temperature of the reaction chamber is adjusted to 1150-1350°C.

[0103] Advantageously, at these temperatures, the etching rate can be controlled to balance the reactivity of the etching process and the amount of byproducts in particulate form (if any).

[0104] Furthermore, within this temperature range, the ratio of Si to C etched by chlorine radicals is optimized relative to the overall etching process itself. Higher temperatures result in more prevalent Si etching, while at lower temperatures, the etching process is generally less efficient.

[0105] A significant advantage is that the above method can be used to etch SiC deposits in situ and out of situ from one or more workpieces in the reaction chamber.

[0106] For in-situ etching applications, the possibility of chemically cleaning the reaction chamber after parasitic buildup and setting it under appropriate operating conditions without: (a) opening the reactor, (b) removing the reaction chamber, and (c) exposing its components to air for cleaning is a considerable improvement over current mechanical cleaning techniques.

[0107] Surprisingly, despite the unique and challenging properties of SiC, it can effectively remove hard, disordered parasitic deposits up to hundreds of micrometers in size without damaging the lower part of the reaction chamber.

[0108] The above method meets the long-term industrial need of providing a method for in-situ cleaning of parasitic deposits in the reaction chamber of a SiC reactor.

[0109] In one embodiment, the grain size of the ceramic coating is less than 300 μm, preferably less than 20 μm, and more preferably between 0.1 and 15 μm, as measured by visual inspection of SEM images.

[0110] Advantageously, the capping layer with a relatively small grain size, as described above, can more easily grow around the particles of solid byproducts of the etching process, which can lead to more successful bonding.

[0111] In one embodiment, the ceramic capping layer comprises pyrolytic graphite, silicon carbide, or boron nitride, or is composed of the same.

[0112] Advantageously, these materials can provide a capping layer that is suitable for withstanding subsequent epitaxial SiC deposition processes inside the reaction chamber and avoids or minimizes contamination of the reaction chamber.

[0113] In one embodiment, the ceramic capping layer comprises or is composed of polycrystalline SiC, and step D includes the following sub-steps:

[0114] D1. Adjust the temperature of the reaction chamber to 1150-1400°C; and

[0115] D2. Adjust the pressure in the reaction chamber to 50-500 mbar; and

[0116] D3. The carbon source and silicon source are fed into the reaction chamber at a ratio of C / Si = 0.6-3 (preferably 1-3).

[0117] Any sub-steps D1-D3 can be performed sequentially and / or simultaneously.

[0118] Steps D1-D3 can be performed until a polycrystalline SiC capping layer with a thickness suitable for embedding powdery byproducts (if any) is deposited, for example, up to 20 μm thick.

[0119] The above process can advantageously provide a high-density cover layer, for example, with a density higher than 3000 kg / m³. 3 The coating, preferably with a density close to that of single-crystal SiC (3200 kg / m³), is used. 3 ).

[0120] In one embodiment, the etching process further includes step A3, which is performed prior to step B, wherein:

[0121] A3. Allow inert gas to flow into the reaction chamber.

[0122] All the above sub-steps A1-A3 (in respectively) Figure 3 (As described in boxes 41, 42, and 43) can be executed in any order, including simultaneous execution.

[0123] Steps A1, A2, and optional step A3 can be considered as sub-steps of the general step A (box 40) which changes the reaction chamber ramp to preset etching process conditions; while step B is the actual etching step in which silicon carbide deposition occurs.

[0124] During step A, the pressure and temperature conditions inside the reaction chamber are gradually adjusted from initial values ​​to desired values, thereby protecting the reaction chamber from undesirable effects of sudden changes. These could lead to stress and damage to mechanical components, and / or result in a lack of uniformity in process conditions inside the reaction chamber.

[0125] Once the reaction chamber reaches the required temperature and pressure settings, the actual etching of the SiC parasitic film can be performed according to step B.

[0126] In one embodiment, the etching process also includes a purging process "P" ( Figure 3 , Figure 4 , Figure 6 Box 20), which includes the following steps:

[0127] P1. Adjust the pressure in the reaction chamber to 1 mbar or lower (box 21); and

[0128] P2. Flow inert gas through the reaction chamber to achieve a pressure of 100-1000 mbar inside the reaction chamber (box 22).

[0129] Steps P1 and P2 are performed 1-20 times before and / or after step B.

[0130] Advantageously, the purging process can remove residues from other operations and processes performed in the reaction chamber.

[0131] In one embodiment, the etching process further includes:

[0132] C. Perform the cooling process ( Figures 3-6 (frame 70).

[0133] The method includes the following steps:

[0134] C1. Adjust the temperature of the reaction chamber to below 1000°C (Box 71, Figure 3 The optimal temperature is between 500-900°C; and

[0135] C2. Cooling gas at a pressure of 100-1000 mbar flows inside the reaction chamber (box 72). Figure 3 ).

[0136] Steps C1 and C2 are executed after step B, and can be executed in any order, preferably simultaneously.

[0137] Step C1 can be performed by turning off the heating source and cooling the reaction chamber (primarily by radiation). Step C1 can be accelerated by simultaneously running sub-step C2.

[0138] The cooling gas used in step C2 is any gas suitable for the cooling process from the acceleration chamber to the idle temperature. Those skilled in the art can easily select the most suitable gas based on budget and time constraints. Non-limiting examples of cooling gases include helium, nitrogen, hydrogen, and combinations thereof.

[0139] It may be beneficial to optionally perform 1-20 cycles of the above-described purging process after step B and before or after step C (if present) to remove all trace amounts of the reactive gases used, as well as any byproducts of the etching process that may still be present in the chamber.

[0140] Cooling step C can be advantageously used to establish favorable conditions for performing the further optional purging process, and / or the latter can help achieve the effect of cooling step C more effectively, depending on the order in which they are performed.

[0141] In summary, the optional purging process can be performed as an additional step in the etching process after step B and before step C, and / or after both steps B and C once the etching process is complete.

[0142] In one embodiment, the flow rate of at least the first reactive gas is 5-15 slm (standard liters per minute). Preferably, the flow rate of at least the first reactive gas is >5 slm and <15 slm.

[0143] In one embodiment, silicon carbide deposits are obtained as a byproduct of one or more nominal deposition processes, such as the epitaxial deposition of a single-crystal SiC layer on a rotating substrate, which is performed in the reaction chamber of a reactor, resulting in the formation of deposits on one or more workpieces in the reaction chamber.

[0144] The epitaxial deposition process described above is typically carried out at pressures of 50-200 mbar and temperatures up to 1700°C, usually above 1400°C, and preferably between 1450-1650°C.

[0145] Typically, precursor gases include Si and C precursors. For example, the silicon precursor gas can be a chlorinated compound, preferably dichlorosilane, trichlorosilane, or tetrachlorosilane. The carbon precursor gas can be a hydrocarbon, particularly propane, ethylene, acetylene, or methane. Other types of Si and C precursors can also be used.

[0146] For example, other precursors used for n-doping and p-doping can flow in the deposition unit of the reactor. For instance, the n-source can be nitrogen, acetonitrile, pyrrole, ammonia, hydrazine, hydrogen cyanide, or methylamine.

[0147] Note that the technical characteristics of SiC stacking imparted by the parasitic stacking process can be adequately defined solely by the parasitic process itself. While the latter does impart identifiable features, such as film inhomogeneity and wrinkling, characterizing SiC stacking based on these features would be overly restrictive.

[0148] In one embodiment, step (i) of the method according to the invention is performed by performing one or more epitaxial deposition cycles of a single-crystal SiC layer on the same or different substrates in the reaction chamber of the reactor until a predetermined total thickness T of the single-crystal SiC layer deposited on one or more consecutive substrates is reached during the entire operating time in the chamber, wherein T is preferably 100 μm-2000 μm, even more preferably 200-800 μm, even more preferably 500-700 μm.

[0149] During this step, a parasitic silicon carbide deposit of variable, non-uniform thickness is formed on one or more workpieces in the reaction chamber. The resulting silicon carbide deposit is referred to as having an “equivalent thickness” T, which is the thickness obtained as a result of an ordered layer with a total cumulative thickness T deposited during the nominal deposition process.

[0150] Note that the local thickness of the parasitic membrane can vary greatly and is different from T on average.

[0151] It should be noted that due to the dendritic growth of the membrane, the peak value of the parasitic membrane can be significantly higher than the thickness T.

[0152] In one embodiment, the etching process according to the method of the invention is performed for an equivalent thickness T0.12-0.24 minutes per μm previously deposited on the substrate.

[0153] As previously mentioned, in this art, the equivalent thickness of a parasitic film is not its average or maximum thickness, as the latter may be subject to significant local variations. The equivalent thickness of a parasitic film is defined as the thickness of a single-crystal layer deposited on one or more substrates during one or more successive epitaxial deposition processes. As ordered single-crystal layers grow on the substrate, the parasitic film grows in certain portions of the reaction chamber, exhibiting variable height. Therefore, it is more meaningful to refer to its equivalent thickness, a parameter set and controlled during reactor operation and readily measurable on the actual substrate after the deposition process.

[0154] In contrast to SiC coatings applied to graphite components for protective purposes, silicon carbide deposits can exhibit a surface roughness greater than 6.3 μm Ra.

[0155] In one embodiment, the reactive composition used in step B) further includes a second reactive gas.

[0156] The second reactive gas can be an oxidizing agent.

[0157] The second reactive gas can be H2 or O2.

[0158] In one embodiment, the molar concentration of the second reactive gas in the carrier gas is 0.1-20%. This embodiment is particularly advantageous when the second reactive gas is O2.

[0159] In one embodiment, the molar concentration of the second reactive gas in the carrier gas is 0.1-15%.

[0160] In one embodiment, the molar concentration of the second reactive gas in the carrier gas is 1-10%.

[0161] Preferably, the molar concentration of the second reactive gas in the carrier gas is lower than the molar concentration of the first reactive gas in the carrier gas.

[0162] In some embodiments, the molar concentration ratio between the second reactive gas and the first reactive gas is less than 1:5.

[0163] A third reactive gas can also be used. For example, the second and third reactive gases can be H2 and O2, and vice versa.

[0164] Typically, depending on the type and amount of reactive gas used, the particulate byproducts can exhibit different compositions. According to EDS measurements, when an inorganic chlorine-containing substance is used as the sole reactive gas, carbon is the dominant component of the solid byproducts (i.e., accounting for 90% or more by mass).

[0165] When a mixture of inorganic chlorine-containing substances (e.g., Cl2) and oxidants (e.g., O2) is used together, the main component of the etching byproducts in particulate form is silicon oxide.

[0166] Compared to more reactive gases (such as ClF3), using less corrosive chemicals (i.e., Cl2 or a mixture of Cl2 and O2) during the etching process, followed by the deposition of a capping layer, allows for lower etching rates and successfully eliminates the undesirable effects of powdery residue.

[0167] In one embodiment, step B) includes the following sub-steps:

[0168] B0. Optionally, one or more reactive gases and / or carrier gases may be discharged, i.e., the reaction chamber may be bypassed for a predetermined amount of time, for example by allowing one or more reactive gases and / or carrier gases to flow in a bypass line until a static condition is reached; and

[0169] B1. To vary the flow rate of one or more reactive gases and carrier gases to a corresponding preset nominal flow rate; and

[0170] B2. One or more reactive gases and a carrier gas are delivered into the reaction chamber at the preset nominal flow rate.

[0171] For each of one or more reactive gases and for the carrier gas, steps B0, B1, and B2 may have different or the same start and / or duration.

[0172] For example, inorganic chlorine-containing substances can undergo a ramp time TR1 and a constant time TS1, while inert gases can undergo a ramp time TR2 and a constant time TS2.

[0173] TR1, TS1, TR2, and TS2 can be different from each other.

[0174] The ramp times for inorganic chlorine-containing substances and inert gases can begin at different times, and they can undergo optional and different exhaust times, with the gases bypassing the reaction chamber via bypass lines.

[0175] Note that all parameters mentioned in this embodiment can be provided as user input or as predetermined settings. Predetermined settings can be calculated based on calibration curves provided for a given reactor and the desired results. They can be obtained by those skilled in the art without undue burden and are adaptable to the specific reaction chamber design in use.

[0176] exist Figure 4 and Figure 5 In the illustrated embodiment, the etching process according to the method of the present invention further includes a monitoring step (block 60), and the reaction chamber 100 includes at least one monitoring system 500 adapted to monitor etching parameters indicating the end of the etching process.

[0177] The monitoring step is performed at the end of step B and includes the following sub-steps:

[0178] - Read the preset target value of the etching parameters (box 62), and optionally read the preset tolerance;

[0179] - Read the actual values ​​of the etching parameters (box 61);

[0180] - Check whether the actual value has reached the target value (box 63), optionally within the preset tolerance;

[0181] - Repeat step B until the target value is reached (optionally within the preset tolerance).

[0182] Once the target value is reached, the monitoring process ends.

[0183] The monitoring system can be a detector suitable for detecting the concentration of silicon and / or carbon in the gaseous byproducts produced after each step B, such as a mass spectrometer.

[0184] Advantageously, this embodiment allows for monitoring of the progress of the method according to the invention.

[0185] In one embodiment, the method according to the invention is performed in situ to etch silicon carbide deposits from one or more workpieces in the reaction chamber, i.e., when the reaction chamber is located inside the reactor and the reactor is not opened. For this purpose, the reaction chamber may be provided with at least one gas inlet and at least one gas outlet.

[0186] In this case, during step B, the reactive composition is delivered into the reaction chamber through at least one gas inlet, thereby forming a byproduct of the etching process, which can be partially or completely discharged from the reaction chamber through a gas outlet.

[0187] Advantageously, in-situ cleaning of reaction chamber components allows for a significant reduction in PM time and limits operator exposure to the reaction chamber. Such exposure represents a safety concern requiring sophisticated and time-consuming safety procedures.

[0188] Preferably, but not exclusively, the reaction chamber in this embodiment is an epitaxial reaction chamber.

[0189] According to the above embodiments, the present invention relates to a method for in-situ etching of SiC deposits from one or more workpieces in the reaction chamber of a reactor used for depositing a single-crystal silicon carbide layer on a substrate.

[0190] The method includes the following steps:

[0191] (o) A silicon carbide layer deposition process, preferably an epitaxial process, is performed on one or more rotating substrates in a reaction chamber; thereby

[0192] (i) A silicon carbide deposit is provided on one or more workpieces in a reaction chamber; wherein the reaction chamber is equipped with at least one gas inlet and at least one gas outlet;

[0193] (i I Optional purging process can be performed;

[0194] (i II Optionally, the reaction chamber can be cooled to a temperature of 600-1100°C;

[0195] (i III Remove one or more treated substrates from the reaction chamber;

[0196] (i IV Optional purging process can be performed;

[0197] (i V Optionally, one or more substrates to be processed can be inserted and steps (o)-(i) can be repeated. IV )

[0198] (ii) Perform at least one cycle of the etching process in a reaction chamber, the etching process comprising the following steps:

[0199] a. Adjust the slope of the reaction chamber to the preset etching process conditions;

[0200] B. Etching silicon carbide deposits;

[0201] C. Optionally, a cooling step may be performed;

[0202] P. Optional purging process;

[0203] (iii) Performing at least one cycle of the deposition process (different from the cycle performed in step (o)) in a reaction chamber, wherein the deposition process is a chemical vapor deposition process comprising the following steps:

[0204] D. Depositing a ceramic coating onto one or more workpieces;

[0205] (iii I Optional purging process can be performed;

[0206] After the final step, the above method can be stopped or repeated once or multiple times.

[0207] In addition to step (i) III ) and (i V Except for the retrieval and optional insertion of one or more substrates during the process, all the above steps are performed in the reaction chamber without removing it from the reactor or needing to be near it.

[0208] In the above method, step A includes the following sub-steps:

[0209] A1. Adjust the temperature of the reaction chamber to 800-100°C or 1000-1450°C; and

[0210] A2. Adjust the pressure in the reaction chamber to 100-150 mbar or 150-700 mbar;

[0211] A3. Optionally, an inert gas may be introduced into the reaction chamber;

[0212] Step B includes delivering the reactive composition into the reaction chamber through a gas inlet; wherein the reactive composition comprises one or more reactive gases and a carrier gas.

[0213] The carrier gas is an inert gas. One or more reactive gases include at least a first reactive gas. The first reactive gas is an inorganic chlorine-containing substance, and its molar concentration in the carrier gas is 15–40%.

[0214] Inorganic chlorine-containing substances can be selected from HCl, Cl2, ClF3, CCl4 and combinations thereof.

[0215] A second reactive gas, such as O2 or alternatively H2, may be used in conjunction with an inorganic chlorine-containing substance and delivered within the same reactive composition. Alternatively, in addition to or as a substitute for the inorganic chlorine-containing substance, the second reactive gas may be provided in a subsequent etching step B' and delivered within a second reactive composition that also contains a carrier gas. Throughout step B (and / or B'), the relative concentrations of the first and / or second reactive gases (if present) relative to the carrier gas and relative to each other in the reactive compositions are not necessarily constant over time.

[0216] The deposition process in step (o) can be an epitaxial deposition process of silicon carbide, carried out at a temperature of 1450-1650°C and a pressure of 50-200 mbar.

[0217] Advantageously, the method according to the invention allows for a concentration of 0.01-0.20 g / cm³ per hour. 2 The removal rate of silicon carbide deposits without affecting the integrity of the workpiece in the reaction chamber. This parameter can be measured during the calibration of the method by weighing the affected portion before and after deposition, and by visual inspection before and after etching.

[0218] In one embodiment, the workpiece may include the upper wall, lower wall, and side wall of the chamber, and / or the cover of said walls (upstream, lateral, and / or downstream), if any, as well as rings and other elements of the reaction chamber.

[0219] In one embodiment, the reaction chamber 100 used in the method according to the invention is horizontal and hot-walled (or alternatively, of the type described in U.S. Patent Application 18 / 953,993), and one or more parts (workpieces) to be etched in the reaction chamber are made of graphite, optionally coated with single-crystal or polycrystalline silicon carbide with a roughness <6.3 μm Ra. Alternatively, pyrolytic graphite, diamond, quartz, and / or boron nitride may be provided as the initial coating of the workpiece.

[0220] It has been observed that the method described above works particularly well with the above-described reaction chamber configuration, and is particularly susceptible to parasitic accumulation.

[0221] Parasitic accumulation occurs on graphite components that are critical to preservation. Due to the specific process conditions disclosed herein, the method according to the invention effectively prevents parasitic SiC accumulation without damaging the underlying graphite components.

[0222] Preferably, but not exclusively, the method according to the invention can be performed when the reaction chamber is of the epitaxial, horizontal, and / or crossflow type.

[0223] In any case, the present invention is not limited to a specific reaction chamber design.

[0224] However, for example, refer to Figure 7 and Figure 8 The reaction chamber 100 is configured for the epitaxial deposition of SiC and extends along the longitudinal direction x. The chamber may include an inlet 155 and an outlet 150, which are adapted to allow process gases, purge gases, cooling gases and reactive compositions to flow into and out of the reaction chamber, and to flow through a receiving region 116 adapted to receive a substrate on a substrate holder.

[0225] The receiving area can be a recess. It can be configured to allow positioning of the substrate holder.

[0226] The receiving area can be adapted to rotate the substrate holder during the epitaxial deposition process.

[0227] The chamber can be further equipped with suitable syringes, liners, nozzles, and spray heads to facilitate the entry and exit of any and all of the aforementioned gases.

[0228] The chamber 100 may have a circular or elliptical cross-section in a transverse plane yz perpendicular to the longitudinal direction x. The chamber may include an upper crescent-shaped element 110 and a lower crescent-shaped element 115, both made of graphite and separated by two lateral elements 117 made of polycrystalline SiC and having a surface roughness of 0.5–1 μm Ra.

[0229] The chamber may include other components, such as a cover 120, for protecting the upper wall of the bottom crescent-shaped part 115 from SiC buildup.

[0230] The reaction chamber 100 may also include several insulating elements, of which only element 180 is shown in part.

[0231] The reaction chamber 100 may also include a quartz shell 170. The quartz shell may be a double-walled quartz tube, optionally cooled by a cooling fluid such as water.

[0232] The reaction chamber 100 may be surrounded by an induction coil 200 wound around a quartz shell 170. The coil may be configured to heat the top wall 110 and the bottom wall 115 of the reaction chamber.

[0233] Many other variations of the above-described reaction chamber design can be used in the implementation of this invention.

[0234] In a second aspect, the present invention relates to a silicon carbide reactor 1000 adapted to perform in-situ etching of polycrystalline and / or amorphous silicon carbide deposits on one or more workpieces deposited in a reaction chamber 100 according to any embodiment of the methods described above.

[0235] The reactor 1000 includes at least one reaction chamber 100 for depositing a silicon carbide layer on a substrate, the reaction chamber being provided with a gas delivery system and including at least one gas inlet 155 and at least one gas outlet 150.

[0236] Preferably, the reactor 1000 includes 1-10 reaction chambers 100, and even more preferably 1-4 reaction chambers.

[0237] The reactor can be connected to or may be connected to Si and C precursor sources (1200 and 1250). For example, the silicon precursor gas can be a chlorinated compound, preferably dichlorosilane, trichlorosilane, or tetrachlorosilane. The carbon precursor gas can be a hydrocarbon, particularly propane, ethylene, acetylene, or methane. Other types of precursors can be used.

[0238] The reactor is also connected to, or can be connected to, a precursor source (not shown) for the ceramic capping layer.

[0239] Other sources, such as those used for n- and p-doping, can be connected to or may be connected to the reactor. For example, the n-source can be nitrogen, acetonitrile, pyrrole, ammonia, hydrazine, hydrogen cyanide, or methylamine.

[0240] The reactor is also connected, or can be connected, to a source of the reactive composition via a gas inlet 155, so that the reactive composition is delivered to the reaction chamber via the gas inlet.

[0241] The source of the reactive composition may include a carrier gas (inert gas, preferably Ar or He) source 1100 and an inorganic chlorine-containing substance source 1150.

[0242] Other sources may be present, such as other reactive gas sources, such as H2 and / or O2.

[0243] The term "source" typically refers to pipelines, cylinders, and / or containers used for gases or liquids.

[0244] The reactor 1000 also includes a heating system 200 adapted to heat the reaction chamber to temperatures up to 1700°C for silicon carbide deposition. Specifically, the heating system 200 should be adapted to heat the reaction chamber to temperatures of 800-1450°C (i.e., 800-1000°C or 1000-1450°C, inclusive) to perform the etching process according to the method of the invention. It should be understood that the actual temperature inside the chamber can vary depending on the chamber design, the heating system, and the number of substrates being processed.

[0245] exist Figures 7 to 9 In this case, the heating system is located outside the reaction chamber, but other configurations are also possible.

[0246] The reactor 1000 also includes a vacuum system 300 adapted to bring the reaction chamber to a pressure of ≤1000 mbar, for example, between 100 and 1000 mbar. The vacuum system 300 may include at least one pump.

[0247] The pump is suitable for (a) depressurizing the reaction chamber 100 and / or (b) allowing exhaust gases (generated by the deposition and etching processes and / or cooling steps) to flow out of the reaction chamber through outlet 150 and into scrubber 400. The vacuum system may also include at least one valve, preferably a throttle valve upstream of the vacuum pump.

[0248] One or more gas outlets also allow byproducts of the etching process to be discharged into the scrubber 400.

[0249] Advantageously, the reactor described above is suitable for performing the method according to the invention, thereby having the characteristic of reduced PM time.

[0250] In one embodiment, reactor 1000 further includes processor 600, accessible memory, in-situ etching program, and optional capture program adapted to run the particle capture process, i.e., step (iii) of method 1.

[0251] The in-situ etching program is stored as a sequence of machine language instructions in an accessible memory and is adapted to perform steps A and B (and optional step C) of the etching process according to the method of the present invention.

[0252] The particle capture program is stored as a sequence of machine language instructions in an accessible memory and is adapted to perform step D of the method according to the invention.

[0253] The processor 600 is configured or can be configured to perform an in-situ etching procedure, for example, by actuating a controller 700 that operates sources 1100 and 1150 of a reactive gas mixture.

[0254] The controller 700 may include valves such as throttle valves, pumps, and a system of circuitry capable of controlling the flow rate, timing, and absolute and relative quantities of carrier gas and one or more reactive gases.

[0255] Other controls can be actuated by the processor 600 to control the flow rate, timing, and absolute and relative quantities (not shown) of the ceramic coating precursor.

[0256] The gases used in the etching process can be combined before entering reaction chamber 100. They can enter the reaction chamber in a single flow. Alternatively, they can enter the reaction chamber as multiple flows with different concentrations and / or flow rates and entry times, depending on their injection point and direction. For this purpose, multiple inlets can be used. Alternatively, a single inlet attached to a liner with an isolation zone can be used to accommodate individual gas flows.

[0257] This also applies to different gases used in the nominal deposition process, and / or to different precursor gases used in the particle capture process.

[0258] The processor 600 can be configured or can be configured to control the vacuum system 300 via one or more valves (e.g., throttle valves) and circuitry.

[0259] The reactor 1000 may optionally include a human-machine interface 800 to allow the end user to start the etching process, adjust relevant parameters, and optionally track its progress.

[0260] The human-machine interface 800 may also optionally allow the end user to start the capture process, adjust relevant parameters, and preferably follow its progress.

[0261] In one embodiment, the reaction chamber 100 of reactor 1000 is hot-walled and includes one or more components made of graphite, optionally coated with single-crystal or polycrystalline silicon carbide (or alternatively, pyrolytic graphite, diamond, quartz, and / or boron nitride) having a roughness of less than 6.3 μm Ra. These optional coatings have been observed to work particularly well in the execution of the invention. These coatings, provided to the workpiece from the outset, should not be confused with the capping layers deposited during particle capture, which serve different purposes, typically exhibit different compositions and / or morphological structures, and are applied each time the method is performed.

[0262] The heating system 200 of the reactor 1000 can be an induction system.

[0263] The reactor may be equipped with a monitoring system 500, which is suitable for detecting / monitoring etching parameters that indicate the end of the etching process, and is located downstream of the reaction chamber 100 (after the gas outlet 150) and between the scrubber 400 that treats the waste gas.

[0264] The processor 600 may be optionally configured or configurable to read and detail one or more signals from the monitoring system 500 (if present).

[0265] The reactor according to the invention may include one or more detectors for detecting one or more reactive gases, wherein the detectors include systems and devices adapted to trigger alarms or stop signals to ensure user safety.

[0266] It should be understood that the reactor according to the invention may include any or all other elements necessary or desired in the reactor industry, such as, but not limited to: cabinets, pipes, actuators, monitors, circuits, mass flow controllers, temperature sensors, valves, pumps and / or power units.

[0267] The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of various processes, systems and configurations, as well as other features, functions, actions and / or properties disclosed herein, and any and all equivalents thereof.

Claims

1. A method for etching a silicon carbide deposit from one or more workpieces in a reactor chamber for depositing a silicon carbide layer on a substrate, the method comprising the steps of: (i) Providing a silicon carbide deposit on one or more workpieces, the silicon carbide deposit comprising silicon carbide in polycrystalline and / or amorphous forms; (ii) Perform at least one cycle of the etching process, including the following steps: A1. Adjust the temperature of the reaction chamber to 800-1450°C; A2. Adjust the pressure in the reaction chamber to 100-700 mbar; B. The reactive composition is delivered into a reaction chamber; the reactive composition comprises at least a first reactive gas and a carrier gas; (iii) Performing at least one cycle of a chemical vapor deposition process in a reaction chamber, including the following steps: D. Depositing a ceramic coating onto one or more workpieces; In step B, the carrier gas is an inert gas; and the first reactive gas is an inorganic chlorine-containing substance; and the molar concentration of the first reactive gas in the carrier gas is 15-40%.

2. The method according to claim 1, wherein, During step A1, the temperature of the reaction chamber is adjusted to 1150-1350°C.

3. The method according to claim 1 or 2, wherein, In step D, the grain size of the ceramic capping layer is less than 300 μm, preferably less than 20 μm.

4. The method according to any one of claims 1 to 3, wherein, The ceramic capping layer comprises pyrolytic graphite, silicon carbide, or boron nitride, or is composed of pyrolytic graphite, silicon carbide, or boron nitride.

5. The method according to claim 4, wherein, The ceramic capping layer comprises or is composed of polycrystalline SiC, and step D includes the following sub-steps: D1. Adjust the temperature of the reaction chamber to 1150-1400°C; and D2. Adjust the pressure in the reaction chamber to 50-500 mbar; as well as D3. The carbon source and silicon source are fed into the reaction chamber at a C / Si ratio of 0.6-3; Sub-steps D1-D3 can be executed sequentially and / or simultaneously.

6. The method according to any one of claims 1 to 5, wherein, The etching process also includes the following steps: A3. Allow inert gas to flow into the reaction chamber; Step A3 is performed before step B.

7. The method according to any one of claims 1 to 6, wherein, The etching process also includes the following steps: C1. Adjust the temperature of the reaction chamber to below 1000°C; and C2. Cooling gas at a pressure of 100-1000 mbar flows inside the reaction chamber. Steps C1 and C2 are executed after step B.

8. The method according to any one of claims 1 to 7, wherein, The etching process also includes the following steps: P1. Adjust the pressure in the reaction chamber to 1 mbar or lower; and P2. Inert gas is circulated in the reaction chamber to achieve a pressure of 100-1000 mbar inside the reaction chamber; Steps P1 and P2 are performed 1-20 times before and / or after step B.

9. The method according to any one of claims 1 to 8, wherein, The carrier gas is nitrogen, argon, or helium.

10. The method according to any one of claims 1 to 9, wherein, The flow rate of the first reactive gas is 5-15 slm.

11. The method according to any one of claims 1 to 10, wherein, The silicon carbide deposition is obtained as a byproduct of an epitaxial deposition process of a single-crystal silicon carbide layer on a rotating substrate, performed in the reaction chamber of a reactor; the byproduct is formed on one or more workpieces in the reaction chamber.

12. The method according to any one of claims 1 to 11, wherein, The reactive composition further includes a second reactive gas, and preferably, the second reactive gas is H2 or O2.

13. The method according to claim 12, wherein, The molar concentration of the second reactant gas in the carrier gas is 0.1-20%.

14. The method according to any one of claims 1 to 13, wherein, The method is performed to etch the silicon carbide deposit from one or more workpieces in a reaction chamber located inside a reactor; and wherein the reaction chamber is provided with at least one gas inlet and at least one gas outlet, and wherein, during step B, the reactive composition is delivered into the reaction chamber through at least one gas inlet and forms etching process byproducts in gaseous and optionally particulate form, and wherein the gaseous byproducts are partially or completely discharged from the reaction chamber through at least one gas outlet.

15. The method according to any one of claims 1 to 14, wherein, Step (i) is performed by performing one or more epitaxial deposition cycles of a single-crystal silicon carbide layer on one or more substrates inside the reactor chamber until a predetermined total thickness "T" of the deposited single-crystal silicon carbide layer is reached, wherein T is preferably 50-2000 μm, or even more preferably 100-800 μm.

16. The method according to claim 15, wherein, The duration of step (ii) is 0.12-0.24 minutes per μm of predetermined total thickness "T".

17. The method according to any one of claims 1 to 16, wherein, The inorganic chlorine-containing substances include HCl, Cl2, ClF3, or CCl4.

18. A reactor for depositing a silicon carbide layer on a substrate, comprising: - At least one reaction chamber, said reaction chamber being provided with a gas delivery system and including at least one gas inlet and at least one gas outlet; - A heating system suitable for heating the reaction chamber to temperatures up to 1700°C, particularly 800-1450°C; - A vacuum system suitable for bringing the reaction chamber to a pressure of 1000 mbar or lower, preferably between 100 and 1000 mbar; The reactor is configured to perform the method according to any one of the preceding claims; and the at least one gas inlet is connectable to a source of a first reactive gas and a carrier gas; and the at least one gas outlet is configured to discharge the gaseous byproducts of steps (ii) and (iii).

19. The reactor for deposition according to claim 18, further comprising: - Processor; - Accessible memory; - An in-situ etching program stored as a sequence of machine language instructions in an accessible memory, the program being adapted to perform at least steps A1, A2 and B of the etching process; The processor can be configured to execute an in-situ etching procedure.

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