Method for manufacturing a plurality of polycrystalline silicon carbide substrates

Abstract

The invention relates to a method for manufacturing a plurality of polycrystalline silicon carbide substrates (200), said method comprising the following steps: the formation of a multilayer structure by the alternating deposition of a plurality of polycrystalline silicon carbide layers (20, 21, 22, 23, 24) and a plurality of separating layers (30, 31, 32, 33) on at least one face of a temporary support substrate (10), the detachment of each polycrystalline silicon layer (20, 21, 22, 23, 24) from the multilayer structure by removing the temporary substrate (10) and each separating layer (30, 31, 32, 33) to form a respective polycrystalline silicon substrate (200). Figure for the abstract: Fig 5

Description

Title of the invention: Method for manufacturing a plurality of polycrystalline silicon carbide substrates technical field

[0001] The present invention relates generally to the field of manufacturing silicon carbide substrates for the formation of electronic components. More particularly, it proposes a method for the simultaneous fabrication of a plurality of polycrystalline silicon carbide substrates. State of the art

[0002] For the formation of electronic components, polycrystalline silicon carbide (p-SiC) substrates are commonly used, having on their surface a layer of a single-crystal material such as single-crystal silicon carbide (m-SiC), gallium nitride (GaN), gallium oxide (Ga2O3) or diamond.

[0003] To ensure good mechanical and electrical contact between the substrate support and the single-crystal layer, the p-SiC base substrate must have a homogeneous crystalline quality and a smooth surface. Typically, the preparation of such a base substrate involves the chemical vapor deposition (CVD) of a thick layer of p-SiC onto a temporary substrate, for example a graphite substrate, followed by the removal of the temporary substrate to isolate the thick p-SiC layer.

[0004] Significant thicknesses of the p-SiC layer are then removed to retain only a thin portion with a crystalline quality suitable for the deposition of an m-SiC layer. Thus, the thick p-SiC layer typically has an initial thickness of between 900 and 3000 pm. After the removal of the lower crystalline quality portions, a thickness of approximately 350 pm is typically retained, which has a crystalline quality suitable for receiving an m-SiC layer.

[0005] CVD-deposited p-SiC is very hard and difficult to cut. Due to the grains in its polycrystalline structure, the risk of breakage during cutting is high. Furthermore, each cut work-hardens an area on the surface of the wafers that must be subsequently removed by grinding and / or polishing. This results in significant material loss. For this reason, it is difficult to prepare a p-SiC block with a thickness equivalent to a plurality of base substrates and to cut a plurality of substrates from such a block. Each base substrate is therefore manufactured individually.

[0006] This process is long and laborious. It also involves a significant consumption of p-SiC which is removed before the deposition of the m-SiC layer and is therefore not used in the substrate to be manufactured. Description of the invention

[0007] An object of the invention is to make available a method for the simultaneous manufacture of a plurality of polycrystalline silicon carbide substrates, which is more economical than existing methods.

[0008] To this end, the invention proposes a method for manufacturing a plurality of polycrystalline silicon carbide substrates, said method comprising the following steps: • the formation of a multilayer structure by the alternating deposition of a plurality of polycrystalline silicon carbide layers and a plurality of separating layers on at least one face of a temporary support substrate, • the detachment of each polycrystalline silicon layer from the multilayer structure by removing the temporary substrate and each separating layer to form a respective polycrystalline silicon substrate.

[0009] The use of separation layers allows easy separation of polycrystalline silicon carbide layers without risk of breakage.

[0010] In some embodiments, the deposition of each layer of polycrystalline silicon carbide and each separation layer is carried out simultaneously on the entire outer surface of the temporary support substrate and / or the respective underlying layer.

[0011] The deposition on the periphery of the substrate and thus the use of the temporary support substrate on its two free faces makes it possible to increase the yield of the process.

[0012] The process further includes a step of removing the edges of the multilayer structure after the deposition of the final layer of polycrystalline silicon carbide, so as to expose an edge of the temporary support substrate.

[0013] Particularly advantageously, the temporary support substrate can be made of graphite.

[0014] In a particularly advantageous way, each separation layer is made of carbon, graphite, silicon or silicon nitride (Si3N4).

[0015] In some embodiments, the removal of the temporary support substrate is carried out by combustion under a flow of oxygen at a temperature between 700 and 1100 °C, preferably between 800°C and 900°C.

[0016] In some embodiments, the removal of each separation layer is carried out by combustion.

[0017] In other embodiments, the removal of each separating layer is carried out by sawing or by chemical etching or by laser cutting.

[0018] In some embodiments, the thickness of the temporary support substrate is between 1 and 15 mm.

[0019] In certain embodiments, the thickness of each carbide layer of polycrystalline silicon is between 300 and 1200 pm.

[0020] In some embodiments, the thickness of each separation layer is between 1 and 50 pm.

[0021] In other embodiments, the thickness of each separation layer is between 1 and 500 nm.

[0022] In some embodiments, the thickness of each separation layer increases with the distance from the temporary support substrate.

[0023] Another object of the invention relates to a method for manufacturing a plurality of substrates, each comprising a polycrystalline silicon carbide base substrate and a layer of a monocrystalline material, the method comprising successively: • the implementation of the method as described above to manufacture each polycrystalline silicon carbide substrate, • the smoothing of one front face of each polycrystalline silicon carbide base substrate, and • the transfer of a layer of a single-crystal material onto the front face of each single-crystal silicon carbide base substrate.

[0024] In certain embodiments, the transfer of the single-crystal material layer comprises the following steps: • the formation of a weakening zone by implanting atomic species into a donor substrate in a single-crystal material to delimit a layer of single-crystal material to be transferred, • the bonding of said donor substrate to the front face of the base substrate, • the detachment of the donor substrate along the embrittlement zone so as to transfer the layer of single-crystal material onto the base substrate.

[0025] Another object of the invention relates to an intermediate substrate comprising: • a temporary support substrate, • on at least one face of the temporary substrate, an alternating stack of a plurality of polycrystalline silicon carbide layers and separating layers.

[0026] Advantageously, the temporary support substrate is made of graphite.

[0027] Preferably, each separating layer is made of carbon, graphite, silicon or silicon nitride. Brief description of the figures

[0028] Other features and advantages of the invention will become apparent from the detailed description that follows, with reference to the accompanying drawings, in which:

[0029] Fig. 1 illustrates a temporary support substrate.

[0030] Figure [Fig. 2] illustrates a temporary support substrate comprising a first layer of p-SiC.

[0031] Fig. 3 illustrates a temporary support substrate comprising a first layer of p-SiC and a first separation layer.

[0032] Fig. 4 is a schematic view of a temporary support substrate comprising a plurality of p-SiC layers and a plurality of separation layers.

[0033] Fig. 5 is a schematic view of a temporary support substrate after edge polishing.

[0034] Figure 6 illustrates a plurality of polycrystalline silicon carbide substrates.

[0035] Fig. 7 illustrates the formation of a weakening zone in a donor substrate.

[0036] Figure 8 illustrates the transfer of a single-crystal layer onto a basic substrate. p-SiC.

[0037] Figure 9 illustrates a substrate comprising a p-SiC base substrate and a single-crystal layer on its front face. Detailed description of implementation methods

[0038] Figures 1 to 6 illustrate the steps in the manufacturing process for a plurality of silicon carbide substrates. The substrates are deposited successively onto a temporary support substrate and separated by separating layers. This creates a multilayer structure which is subsequently dissociated into a plurality of individual p-SiC substrates. Temporary support substrate

[0039] With reference to [Fig. 1], the process begins by providing the temporary support substrate 10. Preferably, the temporary support substrate 10 is made of graphite. The temporary support substrate has two main parallel faces: a front face and a rear face.

[0040] Graphite has a coefficient of thermal expansion close to that of silicon carbide. For this reason, it is particularly suitable as a temporary substrate support material for the fabrication of a substrate involving high-temperature steps such as CVD deposition. Furthermore, graphite is easy to remove in a subsequent step of the process, for example by combustion or chemical etching.

[0041] The temporary support substrate has sufficient thickness to be self-supporting and sufficiently stable for the deposition of several successive layers without significant deformation of the temporary support substrate. Preferably, the thickness of the temporary support substrate is between 1 and 15 mm. The temporary support substrate has a sufficiently smooth surface to allow the uniform deposition of several successive layers without significant deformation of their surface. The temporary support substrate has a coefficient of thermal expansion close to that of p-SiC to avoid delaminations and breakage of the substrate during high temperature treatments (phenomenon referred to as "cracking"). Depositing the layers

[0042] With reference to [Fig. 2], a first layer 20 of polycrystalline silicon carbide (p-SiC) is deposited onto the temporary support substrate 10. The p-SiC can have any electrical resistivity suitable for the intended use. In preferred embodiments, the p-SiC is doped, for example, with nitrogen or phosphorus. In other embodiments, the p-SiC has a high electrical resistivity.

[0043] The p-SiC is preferably deposited as micrometric grains, having a homogeneous size and structure throughout the thickness of the layer to be deposited. For the purposes of this text, "micrometric" means a grain size greater than 1 µm in a plane parallel to the front face of the temporary support substrate, i.e., perpendicular to the growth direction of the p-SiC layer. Preferably, the grain size in this plane is less than 100 µm. Particularly advantageously, the grains have a size between 1 µm and 50 µm in a plane parallel to the front face of the temporary substrate. The grains are typically elongated along the growth direction of the p-SiC layer, so that they typically have a size in the growth direction greater than the size in a plane perpendicular to the growth direction.Preferably, the p-SiC grains have a size of less than 250 µm in the growth direction. Particularly advantageously, the grain size in the growth direction is between 1 µm and 100 µm.

[0044] Preferably, the p-SiC 20 layer is deposited by a CVD deposition process. By way of illustration and without limitation, the p-SiC layer is deposited at a temperature between 1100 and 1500°C. Typically, the temporary support substrate is placed in a deposition chamber, and the deposition is carried out so that the p-SiC layer extends over the entire surface of the temporary support substrate, including its circumference. In some embodiments, the p-SiC layer is deposited on both the front and back faces of the temporary support substrate. In other embodiments, the p-SiC layer may be deposited on only one face of the temporary support substrate. In both cases, p-SiC may be deposited on the sides of the support substrate.

[0045] Alternatively, p-SiC can be deposited by physical vapor deposition (PVD) or physical vapor transport (PVT). p-SiC can also be deposited by liquid-phase CVD or atmospheric pressure CVD, high-temperature CVD, or direct liquid injection CVD. p-SiC can also be deposited from of trichlorosiloxane.

[0046] The thickness of the p-SiC layer corresponds to the thickness of the p-SiC substrate to be manufactured and depends on the end use of the p-SiC substrate. Often, the thickness of such a substrate is chosen based on the substrate's dimensions in order to provide a self-supporting and mechanically stable substrate. For example, a p-SiC substrate with a diameter of 150 mm (6”) typically has a thickness greater than 50 µm, more advantageously greater than 100 µm, in order to be self-supporting. To manufacture such a substrate, a first layer 20 is typically deposited with a thickness between 300 µm and 900 µm, preferably between 360 µm and 900 µm. A p-SiC substrate with a diameter of 200 mm (8”) typically has a thickness between 510 µm and 1200 µm. For the manufacture of such a substrate, a first layer 20 with a minimum thickness of 510 pm is typically deposited.

[0047] For subsequent layers, the thickness of each p-SiC layer is, for example, greater than or equal to 500 pm for a substrate with a diameter of 150 mm, and greater than or equal to 650 pm for a substrate with a diameter of 200 mm.

[0048] The maximum thickness of the p-SiC layers can be 900 pm for a substrate with a diameter of 150 mm, and 1.2 mm for a substrate with a diameter of 200 mm.

[0049] It is thus possible to polish the p-SiC substrate to optimize its surface quality and achieve the final thickness.

[0050] With reference to [Fig. 3], a separation layer 30 is subsequently deposited on the p-SiC layer 20. The separation layer 30 can be made of carbon, graphite, silicon, silicon nitride, titanium nitride, or another material that can be easily removed from a p-SiC layer. Preferably, the deposition of the separation layer 30 is carried out in the same deposition chamber as the deposition of the p-SiC layer 20. It is therefore not necessary to remove the substrate from the chamber between successive depositions. This avoids handling of the substrate and the risk of contamination at the interface between the p-SiC layer 20 and the separation layer 30. It also avoids opening and potential contamination of the deposition chamber. The thickness of the separation layer 30 can be nanometric, for example, between 1 and 500 nm, or micrometric, for example, between 1 and 50 pm.

[0051] The separation layer can be deposited over the entire surface of the p-SiC layer. In some embodiments, the separation layer is deposited only on the front face of the temporary support substrate having the p-SiC layer on its front face, or on the front and back faces of a temporary support substrate 10 having a p-SiC layer on its front and back faces.

[0052] Subsequently, with reference to [Fig. 4], successive layers of p-SiC 20, 21, 22, 23, 24 and separation layers 30, 31, 32, 33 are deposited to fabricate a Multilayer structure. The two types of layers are alternated to obtain a structure in which p-SiC layers and separating layers follow one another. A separating layer is always arranged between two successive p-SiC layers. For illustrative purposes, but not limited to, the last layer deposited is a p-SiC layer. Thus, for a multilayer structure with n p-SiC layers, n-1 separating layers are deposited, where n is an integer. Typically, the number of p-SiC layers deposited is between 2 and 20, preferably between 5 and 15.

[0053] Typically, each p-SiC layer and each separating layer are deposited on the entire surface of the respective underlying layer. In this way, a multilayer structure can be achieved on only one front face of the temporary support substrate. Alternatively, a multilayer structure can be achieved simultaneously on the front and back faces of the temporary support substrate. In a preferred embodiment, the temporary support substrate is installed in a deposition chamber, and each layer is deposited on the entire surface of the temporary support substrate or, respectively, on the entire surface of the respective underlying layer.

[0054] The simultaneous use of the front and rear faces of the temporary support substrate makes it possible to increase the yield of the process by doubling the number of layers formed by the same deposition step.

[0055] Typically, when depositing simultaneously on both sides of a substrate, material is also deposited on the edges.

[0056] When both types of layers, namely the p-SiC layers and the separation layers, are deposited in a single chamber, handling of the temporary support substrate is not necessary before the finalization of the multilayer structure. Furthermore, transfers of the substrate into and out of the deposition chamber are avoided, thus preventing contamination of the chamber and the interfaces between the respective layers.

[0057] The thickness of the separation layer is greater than the roughness of the p-SiC layers after the deposition of each respective layer in order to ensure continuity of the separation layer over the entire interface between two successive p-SiC layers.

[0058] Typically, when depositing a plurality of superimposed layers, the roughness increases successively with the number of layers deposited, because the roughness of each lower layer has an influence on the roughness of the layers subsequently deposited.

[0059] For this reason, during the deposition of several successive p-SiC layers, the thickness of the separating layers can advantageously be increased with the number of deposits and the distance of each layer from the temporary support substrate. This makes it possible to compensate for the increase in roughness and to obtain a rel- very smooth for the layers deposited at the end of the process.

[0060] The thickness of the p-SiC layers can also be increased as the deposition progresses. Preferably, the thickness of each layer corresponds to the thickness of the substrate to be fabricated plus the total variation in thickness of the layer directly below it. This allows, on the one hand, for compensation of the increase in roughness. Furthermore, fabricating thicker layers in the rougher areas at the end of the deposition process allows for more extensive polishing after layer separation, thus smoothing the resulting p-SiC substrates.

[0061] Thus, starting with a first p-SiC layer thickness of approximately 360 pm for a substrate with a diameter of 150 mm, the last p-SiC layer can have a thickness of up to 900 pm, preferably approximately 500 pm. Starting with a first p-SiC layer thickness of approximately 510 pm for a substrate with a diameter of 200 mm, the last p-SiC layer can have a thickness of up to 1200 pm, preferably approximately 650 pm. Separation of p-SiC substrates

[0062] After the fabrication of the multilayer structure, the steps of separating the p-SiC layers are carried out in order to form a p-SiC substrate from each respective p-SiC layer.

[0063] If the p-SiC layers and the separation layers have been deposited over the entire surface of the temporary support substrate and / or if the edge of the temporary support substrate has been covered during the deposition of successive layers, the edge of the multilayer structure is removed. With reference to [Fig. 5], the p-SiC layers and the separation layers are removed along the edge of the multilayer structure to expose the edge of each respective layer and of the temporary support substrate. The material removal along the edge of the multilayer structure is preferably carried out by mechanical trimming. In some cases, the removal can be carried out by laser cutting.

[0064] The temporary support substrate and the separation layers arranged between the respective p-SiC layers are then removed in order to separate the SiC layers.

[0065] The removal of the temporary support substrate is typically carried out by combustion under a flow of oxygen. The temperature during combustion is typically between 700 and 1100 °C, preferably between 800 °C and 900 °C.

[0066] The removal of the separation layers, for example of carbon or graphite, can also be carried out by combustion. Preferably, the substrate and the separation layers are removed in a single removal step. A single removal increases the efficiency and thus the yield of the process and avoids additional steps. additional combustion and heating.

[0067] The combustion temperature can be chosen according to the material and thickness of the separating layers and can be equal to or different from the combustion temperature of the temporary support substrate. Alternatively, the separating layers can be removed by sawing, chemical etching, or laser cutting, depending on the material, thickness, and number of separating layers. These methods will be explained in more detail in the section on separating layers.

[0068] The thickness of the separation layers can also be chosen according to the removal technique. When the separation layer is intended to be removed by chemical etching or combustion, its thickness is preferably micrometer-thick to facilitate the passage of gases and chemicals used for removal, and for the removal of by-products obtained during the removal process. This method is notably used for separation layers made of carbon, graphite, or silicon or silicon nitride.

[0069] In embodiments including removal by liquid chemical attack, for example for separation layers of silicon or silicon nitride, the thickness of each separation layer is preferably greater than one micrometer per inch of diameter, i.e. about 25 mm in diameter.

[0070] In embodiments in which the removal is carried out by attack with a gas, for example the combustion of carbon and / or graphite, the thickness of each separation layer is preferably greater than 0.1 micrometer per inch of diameter, i.e. by about 25 mm of diameter.

[0071] In some embodiments, the removal of the support substrate is carried out in a step separate from the removal of the separation layers. For example, the removal of the temporary support substrate may be carried out at a different temperature or by a different type of process compared to the removal of the separation layers. In particular, the temporary support substrate may be removed before the separation layers are removed. This subsequently allows the two multilayer structures initially arranged on the two faces of the temporary support substrate to be processed simultaneously.

[0072] With reference to [Fig. 6], the p-SiC layers are separated by the shrinkage step and form independent p-SiC 200 substrates. Finalizing steps can now be carried out, such as grinding the p-SiC 200 substrates, in particular to adjust the thickness of each layer to the target thickness before polishing, polishing of said substrates, heat treatments and / or surface treatments.

[0073] The deposition of the multilayer structure and the subsequent removal of the temporary support substrate thus make it possible to simultaneously manufacture a plurality of p-SiC substrates. This process has a higher yield than the manufacture of individual p-SiC substrates and saves manufacturing time, energy, and to facilitate the process.

[0074] The p-SiC substrates can subsequently be used as a basic substrate for manufacturing substrates for electronic components. Separation layers

[0075] The separation layers are made of a material that can be easily removed in a subsequent step of the process. Preferably, the material of the separation layers can be deposited in the same chamber in which the p-SiC layers are deposited. For example, the separation layers can be deposited by a CVD process.

[0076] The separation layers are made of a material with a surface structure similar to the crystalline structure of p-SiC to facilitate the deposition of additional p-SiC layers after the deposition of each separation layer. The coefficient of thermal expansion of the separation layers is close to that of p-SiC to avoid stress at the interfaces during all high-temperature process steps. Advantageously, the Young's modulus of the separation layer material is lower than the Young's modulus of p-SiC. For example, the separation layers can be made of carbon, graphite, silicon, or silicon nitride (Si3N4). These materials also provide good adhesion at each interface between a separation layer and a p-SiC layer. This adhesion facilitates the manipulation of the multilayer structure during the steps between the deposition and removal of the p-SiC layers.

[0077] As described above, the thickness of the separation layers can be increased by increasing the number of deposits and the distance of each layer from the temporary support substrate. This compensates for the increased roughness and results in a relatively smooth surface for the outer layers.

[0078] The thickness of the separation layers is further chosen so that they can be easily removed during the separation of the p-SiC layers. The thickness also depends on the material of the separation layer, the size of the substrate surface area, and the removal method used. In some cases, the thickness of the separation layer is a few nanometers. In other embodiments, it is thicker and can reach values ​​of up to 50 pm.

[0079] The shrinkage technique is also chosen according to the material and thickness of the separation layers.

[0080] By way of illustration and not limitation, a separation layer of carbon or graphite with a thickness of a few pm can easily be removed by combustion simultaneously or successively with the temporary support substrate.

[0081] In the case of separation layers with a thickness of a few tens of µm, the separation can be achieved by wire sawing. A separation layer in Carbon or graphite is much easier to saw than a solid p-SiC substrate. Residues from the separation layer can be removed by total or partial combustion, and / or grinding.

[0082] Depending on the doping of the p-SiC layers, laser cutting can also be considered. For example, a laser with a wavelength at which the separating layers are opaque while the p-SiC layers are transparent can be chosen, and thus only the separating layers can be removed by irradiation with such a laser.

[0083] In the case of silicon separation layers, thicknesses ranging, for example, from a few tens of nanometers up to approximately 1 pm can be considered. To remove silicon separation layers, the multilayer structure can be placed in a bath of tetramethylammonium hydroxide (TMAH) or tetraethylammonium hydroxide (TEAH) to dissolve the silicon. This step is preferably carried out after the temporary support substrate has been removed by combustion. When the separation layers are made of silicon, it is preferable to limit the temperature of the CVD steps to a temperature below the melting point of silicon, which is 1414°C.

[0084] In other embodiments, the separation layers may be made of silicon nitride (SiN). In this case, the thickness of the separation layers is preferably between a few tens of nanometers and about 1 pm. To remove the silicon nitride separation layers, the multilayer structure can be placed in a bath of phosphoric acid (H3PO4) to dissolve the SiN and separate the p-SiC substrates. This step is preferably carried out after the temporary support substrate has been removed by combustion.

[0085] Carbon, graphite, or silicon separation layers have the advantage that these materials are already present in a CVD deposition chamber in which the silicon carbide layers are deposited. This avoids the need for any additional elements in such a chamber, thereby limiting contamination of the deposition chamber and the substrates to be manufactured. When the p-SiC layers are doped with nitrogen, this element must also be present in the deposition chamber. In this case, the advantage of avoiding contamination also applies to the silicon nitride separation layers. Use of p-SiC substrates

[0086] With reference to Figures 7 to 9, p-SiC substrates can be used for the fabrication of substrates to form electronic components. Such substrates having on their surface a layer of a single-crystal material such as single-crystal silicon carbide (m-SiC), gallium nitride (GaN), gallium oxide (Ga2O3) or diamond.

[0087] After smoothing the front face of a p-SiC substrate fabricated by the process described above, additional surface preparation steps for the transfer of a single-crystal layer may or may not be carried out. A layer of a single-crystal material is then transferred onto the front face of the p-SiC substrate.

[0088] To this end, a donor substrate 400 made of said single-crystal material is provided. With reference to [Fig. 7], as schematically indicated by the arrows, ionic species are implanted into the donor substrate 400. The ionic species are, for example, hydrogen and / or helium. This creates a weakening zone 41 defining a single-crystal layer 40 to be transferred.

[0089] With reference to [Fig. 8], the donor substrate 400 thus implanted is bonded to the p-SiC substrate 200. The bonding can be achieved by direct contact or via one or more layers, for example, of an oxide such as silicon dioxide, metals, for example titanium or tungsten, and / or semiconductors or metalloids, for example amorphous or crystalline silicon, SiC. In either case, it may be planned to activate one or both surfaces, in particular by plasma or ion bombardment, to create dangling bonds before the surfaces to be bonded are brought into contact.

[0090] With reference to [Fig. 9], the donor substrate 400 is detached along the embrittlement zone 41, leading to the transfer of the single-crystal layer 40 onto the base p-SiC 200 substrate. The detachment can be initiated by means of a heat treatment. A finishing treatment can then be applied to the transferred layer to correct any defects related to the implantation and to smooth the free surface of said layer.

Claims

Claims

1. A method of manufacturing a plurality of polycrystalline silicon carbide substrates (200), said method comprising the following steps: • forming a multilayer structure by alternately depositing a plurality of polycrystalline silicon carbide layers (20, 21, 22, 23, 24) and a plurality of separation layers (30, 31, 32, 33) on at least one face of a temporary support substrate (10), • detaching each polycrystalline silicon layer (20, 21, 22, 23, 24) from the multilayer structure by removing the temporary substrate (10) and each separation layer (30, 31, 32, 33) to form a respective polycrystalline silicon substrate (200).

2. A manufacturing method according to claim 1, wherein the deposition of each polycrystalline silicon carbide layer (20, 21, 22, 23, 24) and each separation layer (30, 31, 32, 33) is carried out simultaneously over the entire outer surface of the temporary support substrate (10) and / or the respective underlying layer.

3. The method of claim 2, further comprising a step of removing the edges of the multilayer structure after deposition of the final layer of polycrystalline silicon carbide (24), so as to expose an edge of the temporary support substrate (10).

4. A manufacturing method according to any preceding claim, wherein the temporary support substrate (10) is made of graphite.

5. A manufacturing method according to any preceding claim, wherein each separation layer (30, 31, 32, 33) is made of carbon, graphite, silicon or silicon nitride (Si3N4).

6. Manufacturing method according to any one of the preceding claims, wherein the removal of the temporary support substrate (10) is carried out by combustion under a flow of oxygen at a temperature between 700 and 1100°C, preferably between 800°C and 900°C.

7. A manufacturing method according to claim 5, wherein the removal of each separation layer (30, 31, 32, 33) is carried out by combustion.

8. Method according to one of claims 1 to 4, in which the removal of each separation layer (30, 31, 32, 33) is carried out by sawing or by chemical etching or laser cutting.

9. A manufacturing method according to any one of the preceding claims, wherein the thickness of the temporary support substrate (10) is between 1 and 15 mm.

10. A manufacturing method according to any preceding claim, wherein the thickness of each polycrystalline silicon carbide layer (20, 21, 22, 23, 24) is between 300 and 1200 pm.

11. A manufacturing method according to any preceding claim, wherein the thickness of each separation layer (30, 31, 32, 33) is between 1 and 50 pm.

12. A manufacturing method according to any one of claims 1 to 10, wherein the thickness of each separation layer (30, 31, 32, 33) is between 1 and 500 nm.

13. A manufacturing method according to any preceding claim, wherein the thickness of each separation layer (30, 31, 32, 33) increases with distance from the temporary support substrate.

14. A method of manufacturing a plurality of substrates comprising a polycrystalline silicon carbide base substrate (200) and a layer (40) of a monocrystalline material, the method successively comprising: • a method according to any one of the preceding claims for manufacturing each polycrystalline silicon carbide substrate, • smoothing a front face of each polycrystalline silicon carbide base substrate (200), and • transferring a layer (40) of a monocrystalline material onto the front face of each monocrystalline silicon carbide base substrate (200).

15. Method according to claim 14, in which the transfer of the layer (40) of monocrystalline material comprises the following steps: • the formation of a weakening zone (41) by implantation of atomic species in a donor substrate (400) made of a monocrystalline material to delimit a layer of monocrystalline material to be transferred, • the bonding of said donor substrate (400) on the front face of the base substrate (200), • detaching the donor substrate (400) along the weakening zone (41) so as to transfer the layer (40) of the monocrystalline material onto the base substrate (200).

16. Intermediate substrate comprising: • a temporary support substrate (10), • on at least one face of the temporary substrate (10), an alternating stack of a plurality of layers of polycrystalline silicon carbide (20, 21, 22, 23, 24) and separation layers (30, 31, 32, 33).

17. An intermediate substrate according to claim 16, wherein the temporary support substrate (10) is graphite.

18. An intermediate support substrate according to claim 16 or claim 17, wherein each separation layer (30, 31, 32, 33) is made of carbon, graphite, silicon or silicon nitride.