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), the 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 carbide 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 carbide substrate (200).

Description

[0001] METHOD FOR PRODUCING A PLURALITY OF POLYCRYSTALLINE SILICON CARBIDE SUBSTRATES

[0002] FIELD OF THE INVENTION

[0003] The present invention relates generally to the field of manufacturing silicon carbide substrates for forming electronic components. More particularly, it provides a method for simultaneously manufacturing a plurality of polycrystalline silicon carbide substrates.

[0004] STATE OF THE ART

[0005] Polycrystalline silicon carbide (p-SiC) substrates with a layer of a single-crystal material such as monocrystalline silicon carbide (m-SiC), gallium nitride (GaN), gallium oxide (Ga2O3) or diamond are commonly used for the formation of electronic components.

[0006] To ensure good mechanical and electrical contact between the support substrate and the monocrystalline 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 deposition by chemical vapor deposition (CVD) of a thick layer of p-SiC onto a temporary substrate, for example a graphite substrate, followed by removal of the temporary substrate to isolate the thick layer of p-SiC.

[0007] Significant thicknesses of the p-SiC layer are then removed in order to maintain only a thin portion having a crystalline quality suitable for the deposition of a layer of m-SiC. Thus, the thick layer of p-SiC typically has an initial thickness of between 900 and 3000 pm. After removal of the portions of lower crystalline quality, a thickness of approximately 350 pm is typically retained, which has a crystalline quality suitable for receiving a layer of m-SiC.

[0008] CVD-deposited p-SiC is very hard and difficult to cut. Due to the grains of the polycrystalline structure, the risk of breakage during cutting is high. In addition, each cutting work-hardens an area on the surface of the wafers that must be removed by grinding and / or polishing afterwards. This involves a significant loss of material. 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, from such a block, a plurality of substrates. Each base substrate is therefore manufactured individually.

[0009] 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.

[0010] STATEMENT OF THE INVENTION

[0011] An object of the invention is to provide a method for the simultaneous manufacture of a plurality of polycrystalline silicon carbide substrates, which is more economical than existing methods.

[0012] To this end, the invention provides a method for manufacturing a plurality of polycrystalline silicon carbide substrates, said method comprising the following steps:

[0013] • the formation of a multilayer structure by the alternating deposition of a plurality of layers of polycrystalline silicon carbide and a plurality of separation layers on at least one face of a temporary support substrate,

[0014] • detaching each polycrystalline silicon carbide layer from the multilayer structure by removing the temporary substrate and each separation layer to form a respective polycrystalline silicon carbide substrate.

[0015] The use of separation layers allows easy separation of polycrystalline silicon carbide layers without risk of breakage.

[0016] In some embodiments, the deposition of each polycrystalline silicon carbide layer and each separation layer is performed simultaneously over the entire exterior surface of the temporary support substrate and / or the respective underlying layer.

[0017] 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 efficiency of the process.

[0018] The method then further comprises 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.

[0019] Particularly advantageously, the temporary support substrate may be made of graphite. Particularly advantageously, each separation layer is made of carbon, graphite, silicon or silicon nitride (Sial^).

[0020] 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.

[0021] In some embodiments, wherein the removal of each separation layer is accomplished by combustion.

[0022] In other embodiments, the removal of each separation layer is accomplished by sawing or chemical etching or laser cutting.

[0023] In some embodiments, the thickness of the temporary support substrate is between 1 and 15 mm.

[0024] In some embodiments, the thickness of each polycrystalline silicon carbide layer is between 300 and 1200 μm.

[0025] In some embodiments, the thickness of each separation layer is between 1 and 50 μm.

[0026] In other embodiments, the thickness of each separation layer is between 1 and 500 nm.

[0027] In some embodiments, the thickness of each separation layer increases with distance from the temporary support substrate.

[0028] Another subject of the invention relates to a method for manufacturing a plurality of substrates each comprising a base substrate of polycrystalline silicon carbide and a layer of a monocrystalline material, the method successively comprising: o implementing the method as described above to manufacture each polycrystalline silicon carbide substrate, o smoothing a front face of each base substrate of polycrystalline silicon carbide, and o transferring a layer of a monocrystalline material onto the front face of each base substrate of monocrystalline silicon carbide.

[0029] In some embodiments, the transfer of the layer of monocrystalline material comprises the following steps: o the formation of a weakening zone by implantation of atomic species in a donor substrate made of a monocrystalline material to delimit a layer of monocrystalline material to be transferred, o the bonding of said donor substrate on the front face of the base substrate, o the detachment of the donor substrate along the weakening zone so as to transfer the layer of monocrystalline material onto the base substrate.

[0030] Another subject of the invention relates to an intermediate substrate comprising: o a temporary support substrate, o on at least one face of the temporary substrate, an alternating stack of a plurality of layers of polycrystalline silicon carbide and separation layers.

[0031] Advantageously, the temporary support substrate is graphite.

[0032] Preferably, each separation layer is made of carbon, graphite, silicon or silicon nitride.

[0033] 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 a temporary support substrate.

[0036] Figure 2 illustrates a temporary support substrate comprising a first layer of p-SiC.

[0037] Figure 3 illustrates a temporary support substrate comprising a first p-SiC layer and a first separation layer.

[0038] Figure 4 is a schematic view of a temporary support substrate comprising a plurality of p-SiC layers and a plurality of separation layers.

[0039] Figure 5 is a schematic view of a temporary support substrate after edge polishing.

[0040] Figure 6 illustrates a plurality of polycrystalline silicon carbide substrates.

[0041] Figure 7 illustrates the formation of an embrittlement zone in a donor substrate. Figure 8 illustrates the transfer of a monocrystalline layer onto a p-SiC base substrate.

[0042] Figure 9 illustrates a substrate comprising a p-SiC base substrate and a monocrystalline layer on its front side.

[0043] DETAILED DESCRIPTION OF EMBODIMENTS

[0044] Figures 1 to 6 illustrate the steps of the process for manufacturing a plurality of silicon carbide substrates. The substrates are successively deposited on a temporary support substrate and separated by separation layers. This produces a multilayer structure which is subsequently dissociated into a plurality of individual p-SiC substrates.

[0045] Temporary support substrate

[0046] Referring to Figure 1, we begin by providing the temporary support substrate 10. Preferably, the temporary support substrate 10 is made of graphite. The temporary support substrate has two parallel main faces: a front face and a rear face.

[0047] Graphite has a coefficient of thermal expansion close to that of silicon carbide. For this reason, it is particularly suitable as a temporary support substrate material for the manufacture of a substrate involving high-temperature steps such as CVD deposition. In addition, graphite is easy to remove in a later step of the process, for example by combustion or chemical etching.

[0048] The temporary support substrate has a thickness sufficient to be self-supporting and sufficiently stable for the deposition of several successive layers without relevant 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 surface sufficiently smooth 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 rupture of the substrate during high temperature treatments (a phenomenon referred to as "cracking").

[0049] Depositing the layers

[0050] Referring to Figure 2, a first layer 20 of polycrystalline silicon carbide (p-SiC) is deposited on the temporary support substrate 10. The p-SiC may have any electrical resistivity suitable for the intended use. According to preferred embodiments, the p-SiC is doped, for example with nitrogen or phosphorus. In other embodiments, the p-SiC has a high electrical resistivity.

[0051] The p-SiC is preferably deposited in the form of micrometric grains, having a homogeneous size and structure over the entire thickness of the layer to be deposited. In the present text, the term "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 of 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, such 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 pm in the growth direction. Particularly advantageously, the grain size in the growth direction is between 1 pm and 100 pm.

[0052] Preferably, the p-SiC layer 20 is deposited by a CVD deposition process. Illustratively and non-limitingly, the deposition of the p-SiC layer is carried out 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 certain embodiments, the p-SiC layer is deposited on the front face and the back face 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.

[0053] Alternatively, p-SiC can be deposited by physical vapor deposition (PVD), physical vapor transport (PVT). p-SiC can also be deposited by liquid CVD or atmospheric CVD, high-temperature CVD, or direct liquid injection CVD. p-SiC can also be deposited from trichlorosiloxane.

[0054] 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 according to the dimension of the substrate in order to provide a self-supporting and mechanically stable substrate. For example, a p-SiC substrate having a diameter of 150 mm (6”) typically has a thickness greater than 50 μm, more preferably greater than 100 μm, in order to be self-supporting. For the manufacture of such a substrate, a first layer 20 is typically deposited having a thickness between 300 μm and 900 μm, preferably between 360 μm and 900 μm. A p-SiC substrate having a diameter of 200 mm (8”) typically has a thickness between 510 and 1200 μm. For the manufacture of such a substrate, a first layer 20 having a minimum thickness of 510 μm is typically deposited.

[0055] For subsequent layers, the thickness of each p-SiC layer is, for example, greater than or equal to 500 pm for a 150 mm diameter substrate, and greater than or equal to 650 pm for a 200 mm diameter substrate.

[0056] The maximum thickness of the p-SiC layers can be 900 pm for a 150 mm diameter substrate, and 1.2 mm for a 200 mm diameter substrate.

[0057] This allows polishing of the p-SiC substrate to optimize its surface quality and achieve the final thickness.

[0058] With reference to Figure 3, a separation layer 30 is subsequently deposited on the p-SiC layer 20. The separation layer 30 may 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. The opening and possible contamination of the deposition chamber are also avoided. The thickness of the separation layer 30 may be nanometric, for example between 1 and 500 nm, or micrometric, for example between 1 and 50 μm.

[0059] The separation layer may be deposited over the entire surface of the p-SiC layer. In some embodiments, the separation layer is deposited only on the front side of the temporary support substrate having the p-SiC layer on its front side, or on the front and back sides of a temporary support substrate 10 having a p-SiC layer on its front and back sides.

[0060] Subsequently, with reference to FIG. 4, p-SiC layers 20, 21, 22, 23, 24 and separation layers 30, 31, 32, 33 are successively deposited to manufacture a multilayer structure. The deposition of the two types of layers is alternated to obtain a structure in which the p-SiC layers and the separation layers follow one another. A separation layer is always arranged between two successive p-SiC layers. In an illustrative and non-limiting manner, the last layer 24 deposited is a p-SiC layer. Thus, for a multilayer structure comprising n p-SiC layers, n-1 separation layers are deposited, n being an integer. Typically, a number n of p-SiC layers between 2 and 20, preferably between 5 and 15, are deposited.

[0061] 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 produced only on a front side of the temporary support substrate. Alternatively, a multilayer structure can be produced simultaneously on the front and back sides 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.

[0062] The simultaneous use of the front and back sides of the temporary support substrate makes it possible to increase the efficiency of the process by doubling the number of layers formed by a single deposition step.

[0063] Typically, when simultaneously depositing on both sides of a substrate, material is also deposited on the edges.

[0064] When depositing both types of layers, namely p-SiC layers and separation layers, in a single chamber, handling of the temporary support substrate is not necessary before finalizing the multilayer structure. In addition, transfers to enter and exit the substrate in a deposition chamber are avoided, which prevents contamination of the chamber and the interfaces between the respective layers.

[0065] 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.

[0066] 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 deposited subsequently.

[0067] For this reason, during the deposition of several successive p-SiC layers, the thickness of the separation 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 relatively smooth surface for the layers deposited at the end of the process. The thickness of the p-SiC layers can also be increased as the deposits progress. Preferably, the thickness of each layer corresponds to the thickness of the substrate to be manufactured plus the total variation in thickness at the level of the layer arranged directly below said layer. This makes it possible, on the one hand, to compensate for the increase in roughness. In addition, the production of thicker layers in the rougher areas at the end of deposition allows for more polishing after the separation of the layers in order to smooth the resulting p-SiC substrates.

[0068] Thus, starting from a thickness of the first p-SiC layer of approximately 360 pm for a substrate with a diameter of 150 mm, the last p-SiC layer may have a thickness of up to 900 pm, preferably approximately 500 pm. Starting from a thickness of the first p-SiC layer of approximately 510 pm for a substrate with a diameter of 200 mm, the last p-SiC layer may have a thickness of up to 1200 pm, preferably approximately 650 pm.

[0069] Separation of p-SiC substrates

[0070] 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.

[0071] If the p-SiC layers and the separation layers have been deposited on 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 the successive layers, the edge of the multilayer structure is removed. With reference to Figure 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 the temporary support substrate. The removal of material along the edge of the multilayer structure is preferably achieved by mechanical trimming. In some cases, the removal can be achieved by laser cutting.

[0072] 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.

[0073] Removal of the temporary support substrate is typically achieved by combustion under an oxygen flow. The temperature during combustion is typically between 700 and 1100 °C, preferably between 800 °C and 900 °C.

[0074] The removal of separating layers, for example carbon or graphite, can also be carried out by combustion. Preferably, the support substrate and the separating layers are removed in a single removal step. A single removal increases the efficiency and thus the yield of the process and avoids additional combustion and heating steps.

[0075] The combustion temperature can be chosen depending on the material and thickness of the separation layers and can be equal to or different from the combustion temperature of the temporary support substrate. Alternatively, the separation layers can be removed by sawing, chemical etching, or laser cutting, depending on the material, thickness, and number of separation layers. These methods will be explained in more detail in the section on separation layers.

[0076] 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 attack or combustion, the thickness of said layer is preferably micrometric in order to facilitate the passage of gases and chemicals used for removal, and for the evacuation of by-products obtained during removal. This method is used in particular for separation layers made of carbon, graphite, or silicon or silicon nitride.

[0077] In embodiments including removal by liquid chemical etching, for example for silicon or silicon nitride separation layers, the thickness of each separation layer is preferably greater than one micrometer per inch of diameter, i.e., about 25 mm in diameter.

[0078] In embodiments wherein the removal is accomplished by gas etching, e.g., combustion of carbon and / or graphite, the thickness of each separation layer is preferably greater than 0.1 micrometers per inch of diameter, i.e., by about 25 mm of diameter.

[0079] In some embodiments, the removal of the support substrate is carried out in a separate step 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 than the removal of the separation layers. In particular, the temporary support substrate may be removed before removing the separation layers. This subsequently makes it possible to simultaneously process the two multilayer structures initially arranged on the two faces of the temporary support substrate.

[0080] Referring to Figure 6, the p-SiC layers are separated by the removal step and form independent p-SiC 200 substrates. Finalization 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.

[0081] The deposition of the multilayer structure and subsequent removal of the temporary support substrate thus allows the simultaneous fabrication of a plurality of p-SiC substrates. This process has a higher yield than the fabrication of individual p-SiC substrates and saves manufacturing time, energy, and facilitates the process.

[0082] The p-SiC substrates can then be used as a base substrate to fabricate substrates for electronic components.

[0083] Separation layers

[0084] The separation layers are made of a material that can be easily removed in a later step of the process. Preferably, the material of the separation layers can be deposited in the same chamber in which the deposition of the p-SiC layers is carried out. For example, the separation layers can be deposited by a CVD process.

[0085] The separation layers are made of a material that has a surface structure close to the crystalline structure of p-SiC to facilitate the deposition of other p-SiC layers after the deposition of each separation layer. The coefficient of thermal expansion of the separation layers is close to the coefficient of expansion of p-SiC to avoid stresses at the interfaces during all the process steps carried out at high temperature. Advantageously, the Young's modulus of the material of the separation layers 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 (SisN4). These materials also allow good retention at each interface between a separation layer and a p-SiC layer. This retention facilitates the handling of the multilayer structure during the steps between the deposition and the detachment of the p-SiC layers.

[0086] As described above, the thickness of the separation layers can be increased with the number of deposits and the distance of each layer from the temporary support substrate. This compensates for the increased roughness and provides a relatively smooth surface for the outer layers.

[0087] The thickness of the separation layers is further chosen so that they can be easily removed when separating the p-SiC layers. The thickness further depends on the material of the separation layer, the size of the substrate surface, 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 ​​up to 50 μm.

[0088] The removal technique is also chosen depending on the material and the thickness of the separation layers.

[0089] By way of illustration and without limitation, a carbon or graphite separation layer with a thickness of a few μm can easily be removed by combustion simultaneously or successively with the temporary support substrate.

[0090] In the case of separation layers with a thickness of a few tens of μm, separation can be achieved by wire sawing. A separation layer made of carbon or graphite is much easier to saw than a bulk p-SiC substrate. Residues of the separation layer can be removed by total or partial combustion, and / or grinding.

[0091] 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 only the separating layers can be removed by irradiation with such a laser.

[0092] In the case of silicon separation layers, thicknesses ranging from a few tens of nanometers to about 1 μm 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 temperature of silicon, which is 1414°C.

[0093] 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 μm. To remove silicon nitride separation layers, the multilayer structure may be placed in a bath of phosphoric acid H3PO4 to dissolve the SiN and separate the p-SiC substrates. This step is preferably performed after the temporary support substrate has been removed by combustion.

[0094] Separating layers made of carbon, graphite, or silicon have the advantage that these materials are already present in a CVD deposition chamber in which the silicon carbide layers are deposited. This avoids any additional elements in such a chamber, thus 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 separating layers.

[0095] Use of p-SiC substrates

[0096] Referring to Figures 7 to 9, p-SiC substrates can be used for the fabrication of substrates for forming electronic components. Such substrates have on their surface a layer of a monocrystalline material such as monocrystalline silicon carbide (m-SiC), gallium nitride (GaN), gallium oxide (Ga2Os) or diamond.

[0097] After smoothing the front face of a p-SiC substrate made by the method described above, additional surface preparation steps for transferring a single-crystal layer may or may not be performed. A layer of a single-crystal material is then transferred to the front face of the p-SiC substrate.

[0098] For this purpose, a donor substrate 400 made of said monocrystalline material is provided. With reference to FIG. 7, as shown diagrammatically by the arrows, an implantation of ionic species is carried out in the donor substrate 400. The ionic species are, for example, hydrogen and / or helium. A weakening zone 41 is thus created, defining a monocrystalline layer 40 to be transferred.

[0099] With reference to Figure 8, the donor substrate 400 thus implanted is bonded to the p-SiC substrate 200. The bonding can be carried out by direct contact or by means of one or more layers, for example made 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 provided to activate one or both surfaces, in particular by plasma or ion bombardment, to cause dangling bonds to appear there before bringing the surfaces to be bonded into contact.

[0100] Referring to Figure 9, the donor substrate 400 is detached along the weakening zone 41, which leads to the transfer of the monocrystalline layer 40 onto the base p-SiC substrate 200. The initiation of the detachment can be carried out by means of a heat treatment. A finishing treatment of the transferred layer can then be carried out, so as to cure the defects linked 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: o 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), o detaching each polycrystalline silicon carbide 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 carbide substrate (200).

2. 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 on 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 the deposition of the final layer of polycrystalline silicon carbide (24), so as to expose an edge of the temporary support substrate (10).

4. Manufacturing method according to any one of the preceding claims, in which the temporary support substrate (10) is made of graphite.

5. Manufacturing method according to any one of the preceding claims, in which each separation layer (30, 31, 32, 33) is made of carbon, graphite, silicon or silicon nitride (SisN^.

6. Manufacturing method according to any one of the preceding claims, in which 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. 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 by laser cutting.

9. 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.

10. Manufacturing method according to any one of the preceding claims, in which the thickness of each layer of polycrystalline silicon carbide (20, 21, 22, 23, 24) is between 300 and 1200 pm.

11. Manufacturing method according to any one of the preceding claims, wherein the thickness of each separation layer (30, 31, 32, 33) is between 1 and 50 μm.

12. 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 one of the preceding claims, wherein the thickness of each separation layer (30, 31, 32, 33) increases with the 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: o a method according to any one of the preceding claims for manufacturing each polycrystalline silicon carbide substrate, o smoothing a front face of each polycrystalline silicon carbide base substrate (200), and o transferring a layer (40) of a monocrystalline material onto the front face of each base substrate (200) of monocrystalline silicon carbide.

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

16. Intermediate substrate comprising: o a temporary support substrate (10), o 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. Intermediate substrate according to claim 16, in which the temporary support substrate (10) is made of graphite.

18. An intermediate 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.

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