Method and system for obtaining high-quality cubic silicon carbide

Abstract

To provide a method and a system for obtaining a high-quality cubic silicon carbide.SOLUTION: A method (200) is disclosed. The method (200) includes: a step (205) of supplying a carbon-based substrate (S); a step (210) of performing a chemical vapor deposition process on the carbon-based substrate using a mixture of precursor gases, the mixture including a silicon precursor gas including trichlorosilane and a carbon precursor gas selected from a carbon-carbon double bond hydrocarbon and a carbon-carbon triple bond hydrocarbon; and a step (215) of forming a polycrystalline cubic silicon carbide layer having a {111} orientation through the chemical vapor deposition process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to the field of semiconductor materials. In particular, the present disclosure relates to methods and systems for the growth of high quality cubic silicon carbide. [Background technology]

[0002] Power devices are important components of various power electronic systems.

[0003] Silicon-based power devices have improved significantly over the past few decades, but these devices are approaching performance limits imposed by silicon properties, and further progress can only be achieved by transitioning to more robust semiconductor materials.

[0004] Silicon carbide (SiC) is a wide-bandgap semiconductor material that meets the requirements to replace silicon. It exhibits approximately 10 times higher breakdown field strength and 3 times higher thermal conductivity than silicon, making it particularly attractive for high-power and high-temperature devices.

[0005] As is known, SiC can have many crystalline structures (polytypes). Essentially, polytypes are variants of the same compound that have the same crystalline structure in two spatial directions but a different crystalline structure in a third spatial direction.

[0006] SiC polytypes having a hexagonal crystal structure (also called hexagonal SiC), such as 4H-SiC or 6H-SiC, are known.

[0007] SiC polytypes having a cubic structure (also called cubic SiC or 3C-SiC or β-SiC) are also known.

[0008] 3C-SiC is more suitable for some electronic device manufacturing because it exhibits superior physical properties compared to hexagonal SiC. For example, 3C-SiC is lower cost and has higher electron mobility than 4H-SiC.

[0009] The crystallographic orientation of 3C-SiC can affect its performance and applications. As one example, 3C-SiC with a {111} crystallographic orientation can be used in the fabrication of microelectronic devices due to the low or relatively low surface roughness and high or relatively high electron mobility resulting from the {111} crystallographic orientation. As another example, 3C-SiC with a {111} crystallographic orientation can be used in applications requiring high-quality epitaxial growth, such as the fabrication of high-performance transistors.

[0010] U.S. Patent No. 10,358,741 discloses an inexpensive seed material for liquid phase epitaxial growth of silicon carbide. The seed material for liquid phase epitaxial growth of single-crystal silicon carbide includes a surface layer containing polycrystalline silicon carbide having a 3C crystal polytype. Upon X-ray diffraction of the surface layer, a first-order diffraction peak corresponding to the {111} crystal plane is observed as a diffraction peak corresponding to polycrystalline silicon carbide having a 3C crystal polytype, but no other first-order diffraction peaks having a diffraction intensity equal to or greater than 10 percent of the diffraction intensity of the first-order diffraction peak corresponding to the {111} crystal plane are observed.

[0011] Japanese Patent Application Laid-Open No. 2007-049201 discloses that a highly pure multilayer silicon carbide wafer is provided by a method in which the multilayer silicon carbide wafer is detected by an optical sensor and is stacked by a CVD (Chemical Vapor Deposition) method, with each layer being composed of silicon carbide layers having different light transmittances.

[0012] WO 2022 / 122877 discloses a CVD method for preparing a layer containing uniform {111} oriented SiC crystals, at least a portion of which is formed from a gas mixture containing a silicon source and an aromatic carbon source. Summary of the Invention

[0013] Hexagonal SiC (such as 6H-SiC and 4H-SiC) is already available on the market for power devices. However, 3C-SiC is still not widely used in industry, essentially due to the lack of commercially available 3C-SiC substrates.

[0014] This is mainly due to the high or relatively high density of defects in the crystal structure of 3C-SiC, such as inclusions of other polytypes, twin domains, and stacking faults.

[0015] Polycrystalline cubic (3C) silicon carbide (SiC) layers with a {111} crystal orientation (hereinafter referred to as {111}-oriented polycrystalline 3C SiC layers) can be obtained by a chemical vapor deposition process in which a carrier gas is mixed with a gas containing carbon atoms (i.e., a carbon precursor gas) and a gas containing silicon atoms (i.e., a silicon precursor gas) to obtain a mixture of the corresponding precursor gases (hereinafter referred to as a gas mixture), which is then transported into a reaction chamber where growth or deposition occurs on a heated substrate.

[0016] Applicants have found that known chemical vapor deposition processes are deficient in that they do not provide a uniform distribution of {111} oriented crystal structures (grains).

[0017] Formation of a polycrystalline cubic silicon carbide layer with a {111} crystal orientation is understood to mean that the {111} orientation is perpendicular to the surface of the growing layer.

[0018] Furthermore, in some applications, {111}-oriented polycrystalline 3C SiC layers may be used as source material for the growth of another SiC polytype, 4H-SiC. In these applications, the individual grain characteristics in the {111}-oriented polycrystalline 3C SiC layers are important parameters, and small or relatively small deviations from a perfect {111} grain orientation distribution may indicate suboptimal results for 4H-SiC.

[0019] In view of the above, applicant has devised a method (and system) that allows for obtaining {111} oriented polycrystalline 3C SiC layers with controlled grain orientation that are suitable for large-scale industrial production.

[0020] One or more aspects of the present disclosure are set out in a number of independent claims, and advantageous features of the disclosure are set out in dependent claims, the language of which is incorporated herein by reference (provided with reference to a particular aspect of the present disclosure that applies mutatis mutandis to any other aspect thereof).

[0021] One aspect of the present disclosure is - providing a carbonaceous substrate; - carrying out a chemical vapor deposition process on said carbonaceous substrate using a mixture of precursor gases, said precursor gases comprising: a silicon precursor gas comprising trichlorosilane; conducting a chemical vapor deposition process comprising: a carbon precursor gas selected from carbon-carbon double bond hydrocarbons and carbon-carbon triple bond hydrocarbons; - forming a polycrystalline cubic silicon carbide layer having a {111} crystallographic orientation through said chemical vapor deposition process.

[0022] According to one embodiment, the carbon precursor gas is ethylene.

[0023] According to one embodiment, the molar ratio between carbon and silicon (carbon / silicon) in said mixture of precursor gases is between 0.46 and 1.

[0024] According to one embodiment, said mixture of precursor gases comprises a carrier gas, and the molar ratio between silicon and carrier gas (silicon / carrier gas) is between 0.02 and 0.05.

[0025] According to one embodiment, the chemical vapor deposition process is carried out at a temperature between 1150°C and 1350°C.

[0026] According to one embodiment, the chemical vapor deposition process is carried out at a pressure between 3 kPa and 40 kPa, preferably between 3 and 10 kPa.

[0027] According to one embodiment, the carbonaceous substrate comprises isotropic graphite.

[0028] According to one embodiment, the layer obtained by this method may be between 10 micrometers and 1000 micrometers thick.

[0029] They may also be configured to grow on both sides (opposite sides) of the carbonaceous substrate.

[0030] Another aspect of the present disclosure relates to a system comprising a reaction chamber, a support member adapted to support a substrate, a heating device configured to heat the support member during a chemical vapor deposition process, and a gas delivery system. During the chemical vapor deposition process, the gas delivery system is configured to mix a carrier gas with a carbon precursor gas and a silicon precursor gas to obtain a corresponding precursor gas mixture and deliver the precursor gas mixture into the reaction chamber to obtain a polycrystalline cubic silicon carbide layer having a {111} crystal orientation. The silicon precursor gas includes trichlorosilane, and the carbon precursor gas is selected from carbon-carbon double-bond hydrocarbons and carbon-carbon triple-bond hydrocarbons.

[0031] These and other features and advantages of the present disclosure will become apparent from the following description of several illustrative and non-limiting embodiments, which, for a better understanding, should also be read in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0032] [Figure 1] 1 illustrates a schematic diagram of a system according to an embodiment of the present disclosure. [Figure 2] 2 illustrates a method performed by the system of FIG. 1 according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0033] Referring to the drawings, FIG. 1 schematically illustrates a system 100 according to an embodiment of the present disclosure.

[0034] Hereinafter, when one or more configurations of system 100 (and methods implemented thereby) are described by the phrase "according to one embodiment," they should be interpreted as additional or alternative configurations to any previously introduced configurations, unless otherwise indicated and / or unless there is an obvious incompatibility between the combinations of configurations that would be readily apparent to one of ordinary skill in the art.

[0035] In the following, directional terms (e.g., upper, lower, longitudinal, and vertical) related to system 100 refer to directions in the figures that are assumed to be exemplary orientations of use. In particular, directional terms related to system 100 refer to mutually orthogonal reference directions X and Y (hereinafter referred to as the longitudinal and vertical directions, respectively).

[0036] According to one embodiment, the system 100 is configured to perform a chemical vapor deposition (CVD) process aimed at growing or depositing silicon and carbon on a substrate S to obtain or synthesize a polycrystalline cubic (3C) silicon carbide (SiC) layer having a crystalline orientation {111} (hereinafter, a {111}-oriented polycrystalline 3C SiC layer).

[0037] According to one embodiment, the system 100 comprises a reaction chamber 105 (which defines an inner cavity).

[0038] According to one embodiment, the system 100 includes one or more insulating covers (not shown) configured to insulate the reaction chamber 105 from the external environment.

[0039] According to one embodiment, the system 100 includes a support member (referred to as a "susceptor") 115 adapted to support the substrate S. According to one embodiment, the susceptor 115 is a flat or substantially flat member. According to one embodiment, the susceptor 115 is formed of or contains a material (such as graphite) that has a high or relatively high melting temperature.

[0040] According to one embodiment, the system 100 includes a heating device 120 configured to heat the susceptor 115 (and the substrate S supported thereby).

[0041] According to one embodiment, the heating device 120 may be or may comprise an induction heating device. By way of example, the heating device 120 may be or may comprise one or more radio frequency energized coils.

[0042] According to one embodiment, the heating device 120 may be or may comprise a resistive heating device. By way of example, the heating device 120 may be or may comprise one or more carbide coated resistors.

[0043] Without loss of generality, the heating device 120 may be configured to heat the substrate S on one side (in this example, the susceptor is typically referred to as a cold-wall susceptor) or on both sides (in this example, the susceptor is typically referred to as a hot-wall susceptor).

[0044] According to one embodiment, the system 100 includes a gas delivery system 125 .

[0045] According to one embodiment, the gas delivery system 125 couples a carrier gas C with a carbon atom-containing gas (i.e., a carbon precursor gas) P C , and a gas containing silicon atoms (i.e., a silicon precursor gas) PSi and thereby obtain a corresponding precursor gas mixture (hereinafter gas mixture) M.

[0046] According to one embodiment, the gas delivery system 125 is configured to deliver a gas mixture M into the reaction chamber 105 (e.g., through a corresponding chamber inlet IN), where growth or deposition occurs on a heated substrate S, and to discharge a corresponding waste product W outside the reaction chamber 105 (e.g., through a corresponding chamber outlet OUT).

[0047] According to one embodiment, as shown, the reaction chamber 105 and gas delivery system 125 are configured so that the gas mixture M impinges on or covers the substrate S in a direction longitudinal to its major surface (in this example, the reaction chamber is typically referred to as a horizontal flux reaction chamber). In this embodiment, the susceptor 115 supports the substrate S parallel or substantially parallel to the longitudinal direction X.

[0048] According to one embodiment, the substrate S may be positioned relative to the chamber inlet IN according to one or more reference positions that specify one or more geometric parameters of the system 100 .

[0049] According to one embodiment, considering the longitudinal direction X, the geometric parameters are the distance D1 between the chamber inlet IN and the proximal end of the substrate S (i.e., the end of the substrate closer to the chamber inlet IN), the distance D2 between the chamber inlet IN and the distal end of the substrate S (i.e., the end of the substrate farther from the chamber inlet IN), and the longitudinal length l of the substrate S. S The configuration may include one or more (preferably all) of the above.

[0050] According to one embodiment, considering the vertical direction Y, the geometric parameters are the distance D3 between the substrate S (e.g., its main surface or top surface) and the top end of the chamber inlet IN (i.e., the end of the chamber inlet IN that is remote from the substrate S), the vertical length h IN , and the vertical length h of the substrate SS The configuration may include one or more (preferably all) of the above.

[0051] According to one embodiment, not shown, the reaction chamber 105 and gas delivery system 125 are configured so that the gas mixture M impinges on or covers the substrate S laterally relative to its major surface (in this example, the reaction chamber is typically referred to as a vertical flux reaction chamber).

[0052] In accordance with the principles of the present disclosure, a substrate S (e.g., in the form of a plate or disk) is or includes a carbonaceous substrate, and a carbon precursor gas P C is selected from carbon-carbon double bond hydrocarbons (e.g., alkenes) and carbon-carbon triple bond hydrocarbons (e.g., alkynes), and the silicon precursor gas P Si is or comprises trichlorosilane (HSiCl). According to one embodiment, the substrate S (e.g., in the form of a plate or disk) is or comprises a carbonaceous substrate, and the carbon precursor gas P C is or contains ethylene, and the silicon precursor gas P Si is or includes trichlorosilane.

[0053] Carbon precursor gas P C Ethylene was used as the silicon precursor gas P Si The use of trichlorosilane as a precursor gas may reduce safety hazards compared to known precursor gases.

[0054] In addition, the carbon precursor gas P C Ethylene was used as the silicon precursor gas P Si The use of trichlorosilane as a catalyst can increase the growth rate of crystalline structures (or grains) with a {111} crystallographic orientation (hereinafter, {111}-oriented grains). Without loss of generality, the growth rate of {111}-oriented grains can be about 100 μm / hour (or higher).

[0055] According to one embodiment, the carbonaceous substrate may be isotropic graphite and / or a silicon carbide substrate having, for example, high purity (<5 ppm impurities), high operating temperature, high chemical resistance (e.g., due to reduced corrosion by silicon carbide vapor), easy machinability (i.e., the ability to obtain complex or relatively complex shapes to very tight tolerances through a variety of available surface finishing processes), and / or a low coefficient of thermal expansion (CTE) (e.g., 4.2 to 5 10 -6 / K), and density is 1.6 to 1.9 mg / m 3 etc., or may be a composition comprising isotropic graphite and / or any other such carbonaceous material, which exhibits the same or similar chemical / physical properties. The use of isotropic graphite has the advantage of compactness uniformity along the substrate, which is an important feature for heat distribution, thermal uniformity, and impurity levels.

[0056] According to one embodiment, a carbonaceous substrate, such as a carbonaceous substrate comprising isotropic graphite, may be formed by using an isotropic process.

[0057] Without loss of generality, carbonaceous substrates include composite substrates.

[0058] According to one embodiment, the carrier gas C may be hydrogen (H2) or a composition comprising hydrogen (H2). Without loss of generality, the carrier gas C may be one or more inert gases (such as argon), or a combination between one or more inert gases and hydrogen, or a composition comprising one or more inert gases (such as argon), or a combination between one or more inert gases and hydrogen.

[0059] Hereinafter, the carbon precursor gas P C Ethylene was used as the silicon precursor gas PSi Specific values ​​and ranges of values ​​for process (or growth) parameters (e.g., molar ratios, temperatures, pressures, etc.) resulting from experimental testing conducted by applicant using trichlorosilane as a catalyst are described in the following embodiments, which are intended to be preferred and non-limiting. Furthermore, based on the experimental testing, the values ​​or ranges of values ​​described for each process parameter provide advantageous effects both when considered alone and when considered in combination with values ​​or ranges of values ​​for one or more other process parameters.

[0060] According to one embodiment, the molar ratio between carbon and silicon (i.e., the ratio of the molar amounts of carbon and silicon) (carbon / silicon) in the gas mixture M is between 0.46 and 1. According to a preferred embodiment, the molar ratio between carbon and silicon (carbon / silicon) in the gas mixture M is equal to 0.61, thereby <220> It has been found experimentally that this minimizes or at least dramatically reduces the risk of oriented grains and / or unreacted Si.

[0061] According to one embodiment, the molar ratio between silicon and the carrier gas (silicon / carrier gas) is between 0.02 and 0.05, preferably between 0.03 and 0.04. According to a preferred embodiment, the molar ratio between silicon and the carrier gas (silicon / carrier gas) is equal to 0.034, thereby <220> It has been found experimentally that this minimizes or at least dramatically reduces the risk of oriented grains and / or unreacted Si.

[0062] According to one embodiment, the CVD process <220> The CVD process is carried out at a temperature low enough to avoid the formation of grains having a crystal grain size of 0.01 mm or less, and at a temperature high enough to avoid the formation of amorphous or poor quality grains. According to one embodiment, the CVD process is carried out at a temperature between 1150°C and 1350°C. According to a preferred embodiment, the CVD process is carried out at a temperature between 1200°C and 1300°C, preferably at a temperature of 1250°C or 1270°C. These temperatures allow <220> It has been found experimentally that this minimizes or at least dramatically reduces the risk of oriented grains and / or unreacted Si.

[0063] According to one embodiment, the CVD process is carried out at a pressure of 3 kPa to 40 kPa. According to a preferred embodiment, the CVD process is carried out at a pressure of 3 to 10 kPa, for example, about 5 kPa. In this regard, the applicant believes that by carrying out the CVD process at a pressure in this pressure range, i.e., at a pressure (such as the preferred pressure of 5 kPa) that is lower or significantly lower than the conventional pressure conventionally considered necessary to obtain {111} oriented grains, <220> It has been found to be advantageous in that the risk of oriented grains and / or unreacted Si is minimized, or at least dramatically reduced.

[0064] As described above, the substrate S may be positioned relative to the chamber inlet IN according to one or more reference positions that specify one or more geometric parameters of the system 100 .

[0065] In the following, the carbon precursor gas P C Ethylene was used as the silicon precursor gas P Si Specific values ​​and value ranges of geometric parameters (distances D1, D2, D3, longitudinal length l of the substrate S) resulting from experimental tests carried out by the applicant using trichlorosilane as S and vertical length h S and the vertical length h of the chamber inlet IN. IN) are described in accordance with preferred, non-limiting embodiments. Furthermore, based on experimental testing, the values ​​or value ranges described for each geometric parameter provide advantageous effects (particularly on the interaction between the gas mixture M and the substrate S) both when considered alone and when considered in combination with values ​​or value ranges of one or more other geometric parameters.

[0066] In particular, it has been found that the particular values ​​and ranges of values ​​of the geometric parameters mentioned below have a significant effect on the quality and uniformity of the deposited material.

[0067] According to one embodiment, the distance D1 (i.e., the distance along the longitudinal direction X between the proximal end of the substrate S and the chamber inlet IN) is between 40 mm and 100 mm. The preferred value of the distance D1 has been found to be particularly important for obtaining a desired grain orientation.

[0068] According to one embodiment, the distance D2 (ie the distance along the longitudinal direction X between the distal end of the substrate S and the chamber inlet IN) is between 190 mm and 450 mm.

[0069] According to one embodiment, the distance D3 (i.e., the vertical distance between the substrate S and the upper end of the chamber inlet IN) is preferably 20 mm to 40 mm. In this embodiment, there is no or substantially no distance between the substrate S and the lower end of the chamber inlet IN along the vertical direction Y.

[0070] According to one embodiment, the longitudinal length l of the substrate S S is 100mm to 200mm.

[0071] According to one embodiment, the vertical length h of the substrate S S is 1.2mm to 1.8mm.

[0072] According to one embodiment, the vertical length h of the chamber inlet IN IN is 22mm to 34mm.

[0073] Referring to FIG. 2, FIG. 2 illustrates a method 200 according to an embodiment of the present disclosure.

[0074] According to one embodiment, method 200 is performed by system 100, although this should not be construed as limiting.

[0075] According to one embodiment, the method 200 includes providing a carbonaceous substrate S (step 205), where the carbonaceous substrate S is, or includes, for example, isotropic graphite.

[0076] According to one embodiment, providing the carbonaceous substrate includes positioning the carbonaceous substrate S (in the reaction chamber 105, on the susceptor 115) parallel or substantially parallel to the longitudinal direction X (such that the gas mixture M impinges on or covers the carbonaceous substrate S in a longitudinal direction relative to a major surface thereof).

[0077] According to one embodiment, the step of providing the carbonaceous substrate S is performed by adjusting the geometric parameters of the system 100 or at least a subset thereof (e.g., distances D1, D2, D3 between the carbonaceous substrate S and the chamber inlet IN, longitudinal length l of the carbonaceous substrate S, and the like). S and vertical length h S , and the vertical length h of the chamber inlet IN IN This includes setting one or more of the following:

[0078] According to one embodiment, the method 200 comprises a silicon precursor gas P Si as trichlorosilane and carbon precursor gas P C The method includes performing a CVD process on a carbonaceous substrate S using a mixture of precursor gases (i.e., gas mixture M) including ethylene (or, alternatively, other alkenes or alkynes) as a precursor (step 210), and forming a {111}-oriented polycrystalline 3C SiC layer through the CVD process (step 215).

[0079] According to one embodiment, performing a CVD process on a carbonaceous substrate S includes setting process parameters, including, but not limited to, one or more of the molar ratio between carbon and silicon in a gas mixture M (carbon / silicon), the molar ratio between silicon and a carrier gas (silicon / carrier gas), the temperature, pressure, and flow rate of the gas mixture M.

[0080] According to one embodiment, the step of performing a CVD process on a carbonaceous substrate S includes enabling or starting or turning on a gas delivery system 125 to deliver a carrier gas C to a carbon precursor gas P C and silicon precursor gas P Si to obtain a corresponding gas mixture M, and sending the gas mixture M into the reaction chamber 105; and enabling or activating or turning on the heating device 120 to heat the support member 115 (and the substrate S thereon) while the gas mixture M enters the reaction chamber 105, thereby obtaining a {111}-oriented polycrystalline 3C SiC layer on the substrate S.

[0081] Method 200 can result in {111} oriented polycrystalline 3C SiC layers with high quality and evenly distributed {111} oriented grains.

[0082] Therefore, the {111}-oriented polycrystalline 3C SiC layer so obtained is suitable for use as a raw material for obtaining other high-quality SiC polytypes (such as 4H—SiC).

[0083] It should be understood that those skilled in the art may apply numerous logical and / or physical variations and modifications to the above disclosure to meet local and specific requirements. More specifically, while the present disclosure has been described with a certain degree of specificity with reference to preferred embodiments thereof, it should be understood that various omissions, substitutions, and changes in form and details are possible, and other embodiments are possible. In particular, different embodiments of the present disclosure may be practiced without the specific details set forth in the above description to provide a deeper understanding thereof, and conversely, well-known configurations may be omitted or simplified so as not to limit the description with unnecessary detail. Furthermore, it is expressly intended that specific elements and / or method steps described in connection with any disclosed embodiment of the present disclosure may be incorporated into any other embodiment.

[0084] More specifically, the present disclosure may be implemented through equivalent methods (by using similar steps, by eliminating some non-essential steps, or by adding additional optional steps), and further, steps may be performed in different orders, simultaneously, or (at least partially) alternately.

[0085] Furthermore, a system may have different structures or may include equivalent components. Furthermore, any component of a system may be separated into several components, or two or more components may be combined into a single component, or components may be duplicated to support parallel execution of corresponding operations. Furthermore, any interaction between different components (unless otherwise indicated) need not generally be sequential, but may be direct or indirect through one or more intermediaries.

Claims

1. 1. A method (200) comprising: Providing (205) a carbonaceous substrate (S); conducting (210) a chemical vapor deposition process on the carbonaceous substrate using a mixture of precursor gases, the mixture of precursor gases comprising: a silicon precursor gas comprising trichlorosilane; conducting a chemical vapor deposition process (210) comprising: a carbon precursor gas selected from carbon-carbon double bond hydrocarbons and carbon-carbon triple bond hydrocarbons; and forming (215) a polycrystalline cubic silicon carbide layer having a {111} crystallographic orientation through said chemical vapor deposition process.

2. The method (200) of claim 1, wherein the carbon precursor gas is ethylene.

3. The method (200) of claim 2, wherein the molar ratio between carbon and silicon (carbon / silicon) in the mixture of precursor gases is between 0.46 and 1.

4. the precursor gas mixture includes a carrier gas; The method (200) according to claim 2 or 3, wherein the molar ratio between silicon and carrier gas (silicon / carrier gas) is between 0.02 and 0.

05.

5. The method (200) of claim 2 or 3, wherein the chemical vapor deposition process is carried out at a temperature between 1150°C and 1350°C.

6. The method (200) according to claim 2 or 3, wherein the chemical vapor deposition process is carried out at a pressure between 3 kPa and 40 kPa.

7. The method (200) of claim 2 or 3, wherein the carbonaceous substrate (S) comprises isotropic graphite.

8. A system (100), comprising: a reaction chamber (105); a support member (115) adapted to support a substrate (S); a heating device (120) configured to heat the support member (115) during a chemical vapor deposition process; A gas delivery system (125) for delivering a carrier gas (C) to a carbon precursor gas (P) during the chemical vapor deposition process. Ｃ ) and silicon precursor gas (P Ｓｉ a gas delivery system (125) configured to mix the precursor gases (M) with the precursor gases (M) to obtain a corresponding mixture of precursor gases (M) and to deliver the mixture of precursor gases (M) into the reaction chamber (105) to obtain a polycrystalline cubic silicon carbide layer having a {111} crystal orientation, the silicon precursor gas comprises trichlorosilane; The carbon precursor gas is selected from carbon-carbon double bond hydrocarbons and carbon-carbon triple bond hydrocarbons.

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