Method for producing a silicon carbide substrate
Patent Information
- Application Number
- EP2024716148
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-29
- Filing Date
- 2024-03-28
- Publication Date
- 2026-02-11
AI Technical Summary
The preparation of monocrystalline silicon carbide (m-SiC) substrates for electronic components is complex and expensive, requiring a polycrystalline silicon carbide (p-SiC) support substrate with a homogeneous crystalline quality and smooth surface, which is time-consuming and laborious due to the high hardness of silicon carbide and risk of breakage during mechanical treatment.
A method involving the transfer of a monocrystalline silicon carbide layer onto a temporary graphite support substrate, followed by deposition of a polycrystalline silicon carbide layer using chemical vapor deposition, eliminating the need for preparing a support substrate by utilizing the graphite's thermal expansion coefficient to minimize mechanical stresses and prevent breakage, and allowing for direct contact between the layers.
This method reduces the complexity and cost of substrate preparation, increases yield, and ensures good mechanical and electrical contact between the polycrystalline and monocrystalline layers, while minimizing substrate deformation and energy consumption.
Smart Images
Figure EP2024058444_03102024_PF_FP_ABST
Abstract
Description
[0001] METHOD FOR MANUFACTURING A SILICON CARBIDE SUBSTRATE
[0002] FIELD OF THE INVENTION
[0003] The present invention relates generally to the field of silicon carbide substrates for the formation of electronic components. More particularly, it provides a method of manufacturing a substrate comprising a layer of polycrystalline silicon carbide and a layer of monocrystalline silicon carbide.
[0004] STATE OF THE ART
[0005] Monocrystalline silicon carbide (m-SiC) is used for the formation of electronic components, for example for power electronics or radio frequency applications.
[0006] The preparation of m-SiC is complex and expensive. For this reason, instead of using a bulk m-SiC substrate, a polycrystalline silicon carbide (p-SiC) substrate is commonly used, having an m-SiC layer on its surface in which the electronic components are formed. Such substrates are typically manufactured by a Smart Cut™ process, in which an m-SiC layer is transferred onto a p-SiC carrier substrate from a donor substrate.
[0007] To ensure good mechanical and electrical contact between the support substrate and the m-SiC layer, the support substrate must have a homogeneous crystalline quality and a very smooth surface. Such a Smart Cut™ process therefore requires careful preparation of the p-SiC support substrate. This preparation involves depositing a thick layer of p-SiC on a temporary substrate, followed by removing the temporary substrate. A significant thickness of the p-SiC layer is then removed to leave only a thin portion with a crystalline quality suitable for depositing an m-SiC layer. Thus, the thick p-SiC layer typically has an initial thickness of between 900 and 3000 μm. After removing the portion with a lower crystalline quality, a thickness of approximately 350 μm is typically left, which has a crystalline quality suitable for receiving an m-SiC layer.This process therefore involves a significant consumption of p-SiC which is eliminated before the deposition of the m-SiC layer and is therefore not used in the substrate to be manufactured.
[0008] Preparation for the Smart Cut™ process further includes laborious steps to prepare the p-SiC surface to achieve a very smooth surface. Such preparation is necessary for the deposition of the m-SiC layer to achieve good mechanical and electrical contact at the interface between the p-SiC support substrate and the m-SiC layer. These preparation steps typically include treatments such as mechanical and chemical polishing. However, these treatments are difficult to perform on silicon carbide and require considerable time due to its high hardness. The grain boundaries present in the polycrystalline material make smoothing the surface even more difficult. In addition, mechanical processing carries a risk of breakage, rendering the substrate unusable.
[0009] STATEMENT OF THE INVENTION
[0010] An aim of the invention is to design a method for manufacturing a substrate comprising a layer of polycrystalline silicon carbide and a layer of monocrystalline silicon carbide, this method making it possible to dispense with the steps of preparing a support substrate made of polycrystalline silicon carbide described above.
[0011] To this end, the invention proposes a method for manufacturing a substrate comprising a layer of polycrystalline silicon carbide and a layer of monocrystalline silicon carbide in direct contact with the layer of polycrystalline silicon carbide, said method successively comprising the following steps:
[0012] • the transfer of a first layer of monocrystalline silicon carbide onto a front face of a temporary graphite support substrate,
[0013] • a deposit of polycrystalline silicon carbide on the first layer of monocrystalline silicon carbide to form the layer of polycrystalline silicon carbide,
[0014] • removal of the temporary graphite support substrate.
[0015] Such a temporary graphite support substrate is particularly suitable due to its coefficient of thermal expansion, which is close to that of monocrystalline silicon carbide. Thus, the mechanical stresses occurring during cooling after the deposition steps are minimized. The use of such a temporary support substrate thus prevents the substrate from breaking during this step.
[0016] By "successively" is meant in the present text that the steps are carried out in the order in which they are indicated, without excluding the implementation of one or more intermediate steps. Such intermediate steps may for example concern the preparation of the surface of the transferred monocrystalline SiC layer before the deposition of the polycrystalline SiC layer. Advantageously, the method further comprises, before the deposition of polycrystalline silicon carbide, the transfer of a second layer of monocrystalline silicon carbide onto a rear face of the temporary support substrate, the deposition of polycrystalline silicon carbide comprising the formation of a second layer of polycrystalline silicon carbide on the second layer of monocrystalline silicon carbide.
[0017] The use of the temporary support substrate on its two free sides makes it possible to increase the efficiency of the process.
[0018] The method may include applying a bonding layer between each layer of monocrystalline silicon carbide and the temporary support substrate.
[0019] Preferably, the transfer of each layer of monocrystalline silicon carbide onto the temporary support substrate comprises the following steps:
[0020] • the formation of a weakening zone by implantation of atomic species in a donor substrate made of monocrystalline silicon carbide,
[0021] • bonding said donor substrate to a free face of the temporary support substrate,
[0022] • detachment of the donor substrate along the weakening zone so as to transfer a layer of monocrystalline silicon carbide onto the temporary support substrate.
[0023] Advantageously, the deposition of each layer of polycrystalline silicon carbide is carried out by chemical vapor deposition. Chemical vapor deposition ensures very good electrical and mechanical contact between the p-SiC layer and the m-SiC layer.
[0024] Advantageously, the method further comprises a heat treatment after the deposition of a layer of polycrystalline silicon carbide at a temperature higher than the deposition temperature. Preferably, the heat treatment is carried out at a temperature greater than or equal to 1700°C.
[0025] Removing the temporary support substrate may include burning the graphite under an oxygen stream at a temperature between 800°C and 900°C. In some embodiments, removing the temporary support substrate includes chemical etching or oxygen plasma etching. Removing the temporary support substrate may include a grinding step.
[0026] Advantageously, the thickness of the temporary support substrate is between 1 and 15 mm. The thickness of the first layer of monocrystalline silicon carbide may be between 400 nm and 5 pm, preferably between 400 nm and 2 pm and more preferably between 400 nm and 1 pm. Advantageously, the thickness of the first layer of polycrystalline silicon carbide is between 100 pm and 2 mm.
[0027] In some embodiments, the front face of the temporary graphite support has a first size, and the first layer of monocrystalline silicon carbide has a second size less than or equal to half the first size, such that said first layer forms a first tile, the method further comprising transferring at least one second tile of monocrystalline silicon carbide onto the front face of the temporary support substrate such that the first and second tiles are arranged side by side on the front face of the temporary support substrate, the deposition of the layer of polycrystalline silicon carbide comprising forming a respective layer of polycrystalline silicon carbide on each tile.
[0028] The invention also relates to an intermediate substrate comprising:
[0029] • a temporary graphite support substrate,
[0030] • a first layer of monocrystalline silicon carbide arranged on a front face of the temporary support substrate, and
[0031] • a first layer of polycrystalline silicon carbide arranged in direct contact with the first layer of monocrystalline silicon carbide.
[0032] Advantageously, the monocrystalline silicon carbide layer has a thickness of between 400 nm and 5 pm, preferably between 400 nm and 2 pm and more preferably between 400 nm and 1 pm, and the polycrystalline silicon carbide layer has a thickness of between 100 pm and 2 mm.
[0033] Preferably, the front face of the temporary graphite support substrate has a first size, and the first layer of monocrystalline silicon carbide has a second size less than or equal to half the first size so that said first layer forms a first block, the intermediate substrate further comprising at least one second block of monocrystalline silicon carbide, so that the first and second blocks are arranged side by side on the front face of the temporary support substrate, a layer of polycrystalline silicon carbide being arranged on each block of monocrystalline silicon carbide. BRIEF DESCRIPTION OF THE FIGURES
[0034] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:
[0035] Figure 1 illustrates the formation of an embrittlement zone in an m-SiC donor substrate.
[0036] Figure 2 illustrates the transfer of an m-SiC layer onto a temporary support substrate.
[0037] Figure 3 is a schematic view of a temporary support substrate having a layer of m-SiC.
[0038] Figure 4 is a schematic view of a temporary support substrate comprising a layer of m-SiC and a layer of p-SiC.
[0039] Figure 5 illustrates a substrate comprising a layer of polycrystalline silicon carbide and a layer of monocrystalline silicon carbide.
[0040] Figure 6 is a schematic view of a temporary support substrate having two layers of m-SiC.
[0041] Figure 7 is a schematic view of a temporary support substrate having two layers of m-SiC and two layers of p-SiC.
[0042] Figure 8 illustrates two substrates obtained from the temporary support substrate of Figure 7.
[0043] Figure 9 illustrates a temporary support substrate comprising several juxtaposed m-SiC layers.
[0044] DETAILED DESCRIPTION OF EMBODIMENTS
[0045] In the method according to the invention, a temporary support substrate is used onto which a first layer of monocrystalline silicon carbide (m-SiC) is transferred. The temporary support substrate fulfills the function of mechanical support for the m-SiC layer. Due to its temporary nature, the interface between the temporary support substrate and the m-SiC layer requires only a relatively simple basic preparation. This preparation does not involve any complex or critical steps in terms of cleaning, homogeneity and adhesion of the layer to the substrate.
[0046] A layer of polycrystalline silicon carbide (p-SiC) is then deposited on this first layer of m-SiC while the first layer is held on the temporary substrate. During deposition, the temporary support substrate ensures the mechanical stability of the m-SiC layer. Subsequently, the temporary support substrate is removed.
[0047] Figures 1 to 5 illustrate the steps of a method according to the invention. With reference to Figure 1, as shown diagrammatically by the arrows, an implantation of ionic species is implemented in a donor substrate 200 of m-SiC. The ionic species are for example hydrogen and / or helium. A weakening zone 21 is thus created defining a layer 20 of m-SiC to be transferred.
[0048] With reference to FIG. 2, the donor substrate 200 thus implanted is bonded to a temporary graphite substrate 10. The bonding can be carried out by means of an adhesive layer which is applied to the donor substrate and / or to the temporary support substrate before bringing the two substrates into contact. The adhesive layer is for example a layer of silicon, a layer of tungsten, a layer of a polymer or a layer of an oxide.
[0049] Typically, the graphite support substrate has the same surface dimension as the donor substrate 200, for example a diameter of approximately 150 mm or 200 mm. This dimensioning facilitates the handling of the substrates bonded together and allows the use of equipment available in the manufacture of semiconductor substrates. Alternatively, the temporary support substrate may have surface dimensions larger than the dimensions of the donor substrate 200. A larger surface area of the temporary support substrate makes it possible to avoid edge effects and in particular deformations (warping) near the edges of the substrate during the bonding step and the deposition steps described below. The thickness of the temporary support substrate is typically between 1 and 15 mm to ensure sufficient mechanical stability to maintain the m-SiC layer during the process.
[0050] Referring to Figure 3, the donor substrate 200 is detached along the weakening zone 21, for example by a heat treatment or by the application of a mechanical stress, which leads to the transfer of the m-SiC layer 20 onto the temporary graphite substrate 10. A finishing treatment of the transferred layer 20 can subsequently be implemented, for example a polishing and / or a heat treatment. Such a treatment is used to cure the defects linked to the implantation and to smooth the free surface of said m-SiC layer 20 in order to optimize the surface quality for the following steps. In the present invention, a finishing treatment can often be avoided because the deposition of the p-SiC layer will be carried out on the face resulting from the detachment. It is therefore not necessary to provide increased smoothing of the surface obtained during the detachment, since no bonding is carried out on this surface.In addition, any roughness will be compensated for when depositing the p-SiC layer.
[0051] Referring to Figure 4, a layer of polycrystalline silicon carbide 30 is subsequently deposited on the free face of the m-SiC layer 20 arranged on the temporary support substrate 10. Preferably, the p-SiC layer is deposited by a chemical vapor deposition (CVD) process. During CVD deposition, silicon and carbon atoms are sent to the m-SiC layer 20. Thus, direct chemical bonds are established between the atoms of the m-SiC layer 20 and the atoms of the p-SiC layer 30 being deposited, with crystallographic continuity at the interface between the two layers. Chemical vapor deposition thus ensures very good electrical and mechanical contact between the p-SiC layer and the m-SiC layer.
[0052] Typically, the deposition parameters are adjusted so that the p-SiC layer has a fine, micrometric microstructure. This promotes crystallographic continuity at the interface between the two layers, and thus limits the mechanical deformation of the substrate to be manufactured. As an illustration and not a limitation, the deposition of the p-SiC layer is carried out at a temperature between 1100-1500°C.
[0053] CVD deposition is performed on the main surface of the m-SiC layer 20. However, some p-SiC may be deposited on the edges of the substrate and will be removed in a later step. Similarly, some SiC may be deposited on the back side and removed with the temporary support substrate.
[0054] A heat treatment can then be applied to activate dopants in the m-SiC layer 20 and the p-SiC layer 30. A heat treatment can also promote the relaxation of mechanical stresses in the substrate comprising the m-SiC layer 20 and the p-SiC layer 30. These effects improve the crystalline quality and thus the electrical and thermal conductivity at the interface between the m-SiC layer and the p-SiC layer.
[0055] Such heat treatments are typically carried out at a temperature of approximately 1700°C. Thanks to the bonding, the m-SiC layer is held on the temporary support substrate 10 without risk of detachment during the heat treatment.
[0056] When depositing the p-SiC layer, for example in a CVD chamber, material is often deposited on the edges and / or backside of the substrate. If the edge of the temporary support substrate was covered during the deposition of the p-SiC layer, the edge of the substrate is removed to expose the edge of the m-SiC layer and the temporary support substrate. Typically, the p-SiC deposited on the edge of the substrate is removed by chemical etching, mechanical grinding or polishing, or by heat treatment.
[0057] Alternatively, an indentation is created along the edge of the substrate using a diamond tip to form a mechanical weakening zone. Mechanical action is then applied to fracture the substrate along the weakening zone to remove the edge of the substrate.
[0058] With reference to Figure 5, the temporary support substrate 10 is then removed. In an illustrative and non-limiting manner, the removal of the temporary support substrate 10 can be carried out by combustion or by chemical etching. For example, the combustion can be carried out under a flow of oxygen at a temperature between 800 and 900°C. A chemical etching can for example be implemented by the application of nitric acid or by potassium hydroxide. Alternatively, the temporary support substrate can be removed by an oxygen plasma etching step. These steps also make it possible to remove the bonding layer applied for the transfer of the m-SiC layer.
[0059] In some cases, a grinding step is also applied to remove the temporary support substrate without residue on the m-SiC layer.
[0060] In certain embodiments, illustrated in Figures 6 to 8, the two faces of the temporary support substrate are used for the manufacture of two substrates 300A and 300B each comprising a thin layer of m-SiC and a layer of p-SiC. With reference to Figure 6, a first layer of m-SiC 20A is transferred onto a front face of the temporary graphite support substrate 10, and a second layer of m-SiC 20B onto a rear face of the same temporary support substrate 10. The two layers of m-SiC can for example be deposited successively from the same m-SiC donor substrate, or from two separate m-SiC substrates.
[0061] Referring to Figure 7, a respective p-SiC layer 30A, 30B is deposited on each of the m-SiC layers 20A, 20B. Preferably, the two p-SiC layers are deposited simultaneously in the same enclosure, for example a CVD enclosure. This makes it possible to increase the efficiency of the process, by carrying out the deposition of two layers instead of just one for a limited time, and in the same space of the CVD enclosure. For such simultaneous deposition of the two respective faces of the same substrate, a certain amount of p-SiC is typically deposited on the edges of the substrate and will be removed in a later step. The other steps during a process using both faces of the temporary support substrate are carried out in the same manner as described above for the process using only one face of the temporary support substrate.
[0062] In this embodiment, material is also deposited on the edges of the support substrate and the respective p-SiC layers. For this reason, the edge of the substrate is removed so as to expose the edges of the two m-SiC layers and the temporary support substrate. Typically, the p-SiC deposited on the edge of the substrate is removed by chemical etching, mechanical grinding or polishing, or by heat treatment.
[0063] Alternatively, an indentation is created along the edge of the substrate using a diamond tip to form a mechanical weakening zone. Mechanical action is then applied to fracture the substrate along the weakening zone to remove the edge of the substrate.
[0064] This step provides access to the edge of the temporary support substrate for the step of removing said support substrate.
[0065] With reference to Figure 8, after finalizing the layers 30A, 30B, their treatments on the temporary support substrate 10 and the removal of the edge, the temporary support substrate 10 is removed, for example by combustion or by chemical attack. Two substrates 300A and 300B are obtained simultaneously. This variant makes it possible to increase the efficiency of the process by using the two opposite faces of the support substrate.
[0066] In some embodiments, with reference to FIG. 9, a plurality of m-SiC tiles 20C, 20D, 20E are transferred next to each other onto a single face of a temporary support substrate 10. In this case, the temporary support substrate has a surface dimension that is significantly greater than the transferred m-SiC layers 20C, 20D, 20E. The tiles do not overlap and typically an area between the edges of the respective tiles remains free on the temporary support substrate 10. The geometry of the tiles may be round, rectangular, or other. Depending on the shape and size of the tiles and the temporary support substrate, an area near the edge of the temporary support substrate may also remain free.
[0067] It is also possible to transfer several respective m-SiC slabs side by side onto the front and back faces of such a large temporary support substrate. This embodiment also makes it possible to optimize the process yield.
[0068] A simultaneous deposition of a layer of p-SiC is then carried out over the entire surface of the temporary support substrate comprising the plurality of m-SiC blocks 20C, 20D, 20E. The same steps and treatments of the substrate as described above can be applied for a single layer of p-SiC.
[0069] The p-SiC layer deposited in the free areas of the temporary support substrate not having any m-SiC layer is then cut. Illustratively and not by way of limitation, the p-SiC areas deposited on the free areas of the temporary support substrate are removed by laser cutting or cutting with a diamond tip. These methods allow efficient cutting of the p-SiC. The SiC deposited on the edges of the graphite temporary support substrate is also removed in order to expose the edge of the support substrate for graphite removal. Illustratively and not by way of limitation, the SiC on the front side of the temporary support substrate is first cut, and then the SiC on the edges of said temporary support substrate is removed. After this step, the temporary support substrate is removed, for example by combustion or chemical etching.
[0070] Several respective substrates are thus obtained from the several layers of m-SiC transferred at the start of the process.
[0071] Typically, after obtaining one or more substrates comprising a thin layer of m-SiC and a layer of p-SiC, a final shaping step is carried out. Such a step may for example comprise mechanical trimming and / or polishing to remove deposits on the edges of each substrate and to homogenize the edge of each substrate obtained.
[0072] Each layer of m-SiC transferred onto the temporary support substrate has a thickness of between 400 nm and 5 pm. Preferably, the thickness of the transferred m-SiC layer is between 400 nm and 2 pm and more preferably between 400 nm and 1 pm.
[0073] A layer of such thickness is too thin to be self-supporting. During the deposition of each p-SiC layer, said thin m-SiC layer is held on the temporary support substrate by the bonding carried out during the transfer step. The temporary support substrate ensures the mechanical support and stability of the m-SiC layer during the deposition of the p-SiC layer. This allows for a homogeneous deposition of the p-SiC layer with good crystalline quality.
[0074] The use of a thin layer of m-SiC makes it possible to obtain a large number of substrates from the same m-SiC donor substrate. This allows for the optimization of the yield of such a donor substrate, the production of which is difficult and laborious. The limited thickness of the m-SiC layer also reduces the impact of the slight difference in thermal expansion coefficient between the m-SiC layer and the p-SiC layer, which may be present in particular due to different doping of the two layers. The thickness also makes it possible to limit the deformation (warping) of the substrate to be produced, composed of the p-SiC layer 30 and the thin layer of m-SiC 20. Furthermore, the thinner the m-SiC layer, the lower the energy required to create the weakening zone for transfer. It is therefore easier and more energy-efficient to transfer thin m-SiC layers.
[0075] Graphite has a coefficient of thermal expansion close to monocrystalline and polycrystalline silicon carbide. For this reason, it is particularly suitable as a temporary support substrate material for the fabrication of a substrate involving high-temperature steps. High-temperature steps are, for example, the detachment of the donor substrate during the transfer of the m-SiC layer, the deposition of the p-SiC layer such as vapor deposition, and the possible recrystallization and relaxation heat treatments and subsequent ones. Furthermore, graphite can easily be removed, for example, by grinding, chemical etching and / or combustion. It is therefore not necessary to optimize the surface quality and bonding of the m-SiC layer to facilitate the removal of the temporary support substrate at the end of the process.
[0076] The temporary support substrate must be smooth enough to hold the m-SiC layer during the deposition of the p-SiC layer without significant surface deformation. However, the process does not place any constraints on the structure and quality of the graphite used, since the temporary support substrate is removed for the finalization of the silicon carbide substrate.
[0077] Holding the substrate on the temporary support substrate by bonding prevents the risk of detachment of the support substrate during high-temperature steps. A person skilled in the art will be able to choose the type of bonding based on the temperatures and environments expected in the process. Since the bonding is only temporary, the constraints on it are relatively loose. The role of the bonding is only to ensure the mechanical strength of the m-SiC layer during the deposition of the p-SiC layer. It is therefore not necessary to optimize the electrical or thermal conductivity across the bonding interface.
[0078] The deposition of the p-SiC layer can therefore be carried out at a temperature to be chosen according to the desired properties of the p-SiC layer. It is not necessary to limit the temperature window or other process parameters to avoid detachment of the m-SiC layer from its support. Heat treatments, for example for the activation of dopants and for the relaxation of mechanical stresses, can also be carried out without special constraints imposed by the temporary support substrate.
[0079] Each p-SiC layer has a thickness between 100 pm and 2 mm. Such a thickness is sufficient to make the substrate self-supporting over its entire extent after removal of the temporary support substrate.
[0080] The fact that the p-SiC layer is directly deposited on a thin, high-quality crystalline m-SiC layer allows for high-quality p-SiC deposition over the entire thickness of the layer. This avoids the need for an additional step of removing a portion of the p-SiC. Following the deposition of p-SiC on a high-quality crystalline m-SiC surface, the interface between the respective p-SiC and m-SiC layers exhibits good mechanical, electrical, and thermal coupling.
Claims
CLAIMS 1. Method for manufacturing a substrate (300) comprising a layer of polycrystalline silicon carbide (30, 30A, 30B) and a layer of monocrystalline silicon carbide (20, 20A, 30B) in direct contact with the layer of polycrystalline silicon carbide, said method successively comprising the following steps: o transferring a first layer of monocrystalline silicon carbide (20, 20A) onto a front face of a temporary graphite support substrate (10), o depositing polycrystalline silicon carbide on the first layer of monocrystalline silicon carbide (20, 20A) to form the layer of polycrystalline silicon carbide (30, 30A), o removing the temporary graphite support substrate (10).
2. A manufacturing method according to claim 1, further comprising, before the deposition of polycrystalline silicon carbide, the transfer of a second layer of monocrystalline silicon carbide (20B) onto a rear face of the temporary support substrate (10), the deposition of polycrystalline silicon carbide comprising the formation of a second layer of polycrystalline silicon carbide (30B) on the second layer of monocrystalline silicon carbide (20B).
3. A manufacturing method according to claim 1 or claim 2, comprising applying a bonding layer between each layer of monocrystalline silicon carbide (20A, 20B) and the temporary support substrate (10).
4. Manufacturing method according to any one of the preceding claims, wherein the transfer of each layer of monocrystalline silicon carbide (20, 20A, 20B) onto the temporary support substrate (10) comprises the following steps: o the formation of a weakening zone (21) by implantation of atomic species in a donor substrate (200) made of monocrystalline silicon carbide, o the bonding of said donor substrate (200) onto a free face of the temporary support substrate (10), o the detachment of the donor substrate (200) along the weakening zone (21) so as to transfer a layer (20, 20A, 20B) of monocrystalline silicon carbide onto the temporary support substrate (10).
5. Manufacturing method according to any one of the preceding claims, in which the deposition of each layer of polycrystalline silicon carbide (30, 30A, 30B) is carried out by chemical vapor deposition.
6. A manufacturing method according to any one of the preceding claims, further comprising a heat treatment after the deposition of a layer of polycrystalline silicon carbide (30, 30A, 30B) at a temperature above the deposition temperature.
7. Manufacturing method according to claim 6, in which the heat treatment is carried out at a temperature greater than or equal to 1700°C.
8. Manufacturing method according to any one of the preceding claims, wherein the removal of the temporary support substrate (10) comprises combustion of the graphite under a flow of oxygen at a temperature between 800°C and 900°C.
9. A manufacturing method according to any one of the preceding claims, wherein the removal of the temporary support substrate (10) comprises chemical etching or oxygen plasma etching.
10. A manufacturing method according to any one of the preceding claims, wherein the removal of the temporary support substrate (10) comprises a grinding step.
11. Manufacturing method according to any one of the preceding claims, in which the thickness of the temporary support substrate (10) is between 1 and 15 mm.
12. A manufacturing method according to any one of the preceding claims, wherein the thickness of the first layer of monocrystalline silicon carbide (20, 20A) is between 400 nm and 5 pm, preferably between 400 nm and 2 pm, and more preferably between 400 nm and 1 pm.
13. Manufacturing method according to any one of the preceding claims, wherein the thickness of the first layer of polycrystalline silicon carbide (30, 30A) is between 100 μm and 2 mm.
14. A manufacturing method according to any one of the preceding claims, wherein the front face of the temporary graphite support (10) has a first size, and the first layer of monocrystalline silicon carbide has a second size less than or equal to half the first size, such that said first layer forms a first block (20C), the method further comprising transferring at least one second block of monocrystalline silicon carbide (20D, 20E) onto the front face of the temporary support substrate (10) such that the first and second blocks (20C, 20D, 20E) are arranged side by side on the front face of the temporary support substrate (10), the deposition of the layer of polycrystalline silicon carbide comprising the formation of a respective layer of polycrystalline silicon carbide on each block (20C, 20D, 20E).
15. Intermediate substrate comprising: o a temporary support substrate (10) made of graphite, o a first layer of monocrystalline silicon carbide (20, 20A) arranged on a front face of the temporary support substrate (10), and o a first layer of polycrystalline silicon carbide (30, 30A) arranged in direct contact with the first layer of monocrystalline silicon carbide (20, 20A).
16. Intermediate substrate according to claim 15 wherein the layer of monocrystalline silicon carbide (20, 20A) has a thickness of between 400 nm and 5 pm, preferably between 400 nm and 2 pm and more preferably between 400 nm and 1 pm, and the layer of polycrystalline silicon carbide (30, 30A) has a thickness of between 100 pm and 2 mm.
17. Intermediate substrate according to claim 15 or claim 16, wherein the front face of the temporary graphite support substrate (10) has a first size, and the first layer of monocrystalline silicon carbide has a second size less than or equal to half the first size so that said first layer forms a first block (20C), the intermediate substrate further comprising at least one second block (20D, 20E) of monocrystalline silicon carbide, such that the first and second tiles (20C, 20D, 20E) are arranged side by side on the front face of the temporary support substrate (10), a layer of polycrystalline silicon carbide being arranged on each tile (20C, 20D, 20E) of monocrystalline silicon carbide.