Method for fabricating a composite structure containing a thin layer of single-crystal SiC on a polycrystalline SiC support substrate.

Abstract

A method for manufacturing a composite structure including a thin layer made of monocrystalline silicon carbide, comprising the steps of: a) providing an initial substrate made of monocrystalline silicon carbide and a carrier substrate made of polycrystalline silicon carbide; b) a porosification step applied to the initial substrate in order to form a porous layer on the front side of the initial substrate; c) a surface layer made of amorphous silicon carbide on the front side of the carrier substrate; d) bonding the initial substrate and the carrier substrate at their respective front sides to produce a first intermediate structure; e) a heat treatment step applied to the first intermediate structure at a temperature above 900° C. in order to form a thin layer, starting from the contact interface with the porous layer, thereby producing a second intermediate structure; and f) a separation step within the porous layer of the second intermediate structure in order to obtain, on the one hand, the composite structure and, on the other hand, the remaining part of the initial substrate.

Description

[Technical Field]

[0001] (Field of the Invention) The present invention relates to the field of semiconductor materials for microelectronic components. In particular, the present invention relates to a method for fabricating a composite structure comprising a thin layer of single-crystal silicon carbide on a carrier substrate made of polycrystalline silicon carbide. [Background Art]

[0002] (Technical Background of the Invention) SiC is increasingly widely used to fabricate innovative power devices, particularly to meet the growing demand of growing electronic applications such as electric vehicles.

[0003] Power devices and integrated power systems based on single-crystal silicon carbide can handle much higher power densities than their conventional silicon counterparts, and can do so in an active region of smaller size. To further limit the dimensions of power devices on SiC, it would be preferable to fabricate vertical components rather than horizontal components. To do this, vertical electrical conduction between an electrode disposed on the front side and an electrode disposed on the back side of the SiC structure must be permitted by said structure.

[0004] Nevertheless, high-quality single-crystal SiC (c-SiC) substrates for the microelectronics industry remain expensive and difficult to supply in large sizes. Therefore, it is preferable to use layer transfer solutions to manufacture a composite structure that typically comprises a thin layer of single-crystal SiC (obtained from a high-quality c-SiC substrate) on a low-cost carrier substrate made of, for example, polycrystalline SiC (p-SiC).

[0005] One well-known thin-layer transfer solution is the Smart Cut® process, which uses bonding by implanting light ions into a single-crystal donor substrate and bonding them directly to a carrier substrate at the bonding interface. The transfer of the thin layer from the donor substrate to the carrier substrate is achieved by fracture along the embedded weakened surface created by the implantation of light ions.

[0006] In particular, another known transfer solution for silicon substrates is the Eltran® process, which involves bonding a thin single-crystal layer to a porous layer that is epitaxially grown and directly bonded to a support substrate. The transfer of the thin layer to the support substrate is carried out by separation within the porous layer. Object of the Invention

[0007] This invention relates to an alternative solution to a prior art solution. The invention relates to a method for fabricating a composite structure comprising a thin layer of single-crystal SiC placed on a polycrystalline SiC support substrate. The invention also relates to an intermediate structure obtained in the said fabrication method. [Overview of the project]

[0008] (Brief description of the invention) The present invention relates to a method for fabricating a composite structure including a thin layer made of single-crystal silicon carbide, which is placed on a support substrate made of polycrystalline silicon carbide. a) Providing an initial substrate made of single-crystal silicon carbide having a front and a back surface, and a support substrate made of polycrystalline silicon carbide having a front and a back surface, b) A porosizing step applied to the initial substrate in order to form a porous layer at least on the front side of the initial substrate, c) The step of forming a surface layer made of amorphous silicon carbide on the front surface and / or porous layer of the support substrate, d) A step in which the initial substrate and the support substrate are joined at their respective front surfaces to manufacture the first intermediate structure, e) A heat treatment step applied to a first intermediate structure at a temperature exceeding 900°C to form a thin layer, starting from the contact interface with a porous layer, in order to crystallize the surface layer at least partially in the form of single-crystal silicon carbide, thereby producing a second intermediate structure. f) A step of separating the composite structure within the porous layer of the second intermediate structure in order to obtain the composite structure on the one hand and the remaining portion of the initial substrate on the other hand. This includes methods.

[0009] According to other preferred and non-limiting features of the present invention, the following should be considered individually or in any technically feasible combination: At the end of step b), the porous layer has a thickness of 0.5 μm to 5 μm; At the end of step b), the porous layer contains pores with a size of 1 nm to 50 nm and has a degree of porosity of 10% to 70%; At the end of c), the surface layer has a thickness of 10 μm or less; At the end of c), the surface layer has a thickness of 1 μm or less, typically around 100 to several hundred nanometers; Step c) includes depositing an amorphous silicon carbide layer at least on the front side of the support substrate and / or on at least the porous layer in order to form a surface layer; The deposited amorphous silicon carbide layer is highly doped, 10 19 / cm 3 exceeding, or 10 20 / cm 3 Having a dopant species concentration exceeding the above; Step c) includes amorphousizing at least the front surface layer of the carrier substrate in order to form a surface layer; Step d) includes forming a bonding layer on one and / or the other side of the substrate, on each of its respective faces, before bonding the initial substrate and the support substrate, wherein the bonding layer has a total thickness of 10 nm or less after bonding; The bonding layer is composed of at least one material selected from silicon, nickel, titanium, and tungsten; During step e), the binding layer is segmented into nodules or dissolved to allow at least locally direct contact between the surface layer and the porous layer or between the surface layer and the support substrate; The heat treatment in step e) is carried out at a temperature of 1000°C or higher, preferably 1400°C or higher, or 1850°C or higher; In step e), crystallization of the surface layer occurs at least partially in the form of polycrystalline silicon carbide, starting from the contact interface with the support substrate in order to form the intermediate layer; The present manufacturing method includes a finishing step g) after step f), which involves mechanical and / or chemical treatment of the composite structure to remove any residue from the porous layer from the front of the thin layer and / or to correct the thickness uniformity of the composite structure; Step g) includes a heat treatment applied to the composite structure at a temperature of 1000°C to 1900°C before or after mechanical and / or chemical treatment; This manufacturing method includes the step of readjusting the remaining portion of the initial substrate for reuse as an initial substrate for fabricating a new composite structure.

[0010] The present invention also, A support substrate made of polycrystalline silicon carbide, A surface layer made of amorphous silicon carbide is placed on the front side of the support substrate, A porous layer placed on the surface, Initial substrate made of single-crystal silicon carbide on a porous layer and Equipped with, The porous layer is in direct contact with the surface layer, or is arranged via a bonding layer, and a bonding interface exists between the porous layer and the surface layer, or The surface layer is in direct contact with the carrier substrate, or is arranged via a binding layer, and a binding interface exists between the carrier substrate and the surface layer, or The surface layer on the porous layer side is in direct contact with another surface layer on the support substrate side, or is arranged via a binding layer, and the binding interface exists between the two surface layers. Regarding the intermediate structure.

[0011] Other features and advantages of the present invention will become apparent upon reading the following detailed description of the present invention with reference to the accompanying drawings. Brief Description of the Drawings

[0012] [Figure 1] Shows a composite structure manufactured using the fabrication method according to the present invention. [Figure 2a] Shows steps of the fabrication method according to the present invention. [Figure 2b] Shows another step of the fabrication method according to the present invention. [Figure 2c] Shows a further step of the fabrication method according to the present invention. [Figure 2c-1] Shows a further step of the fabrication method according to the present invention. [Figure 2d] Shows a further step of the fabrication method according to the present invention. [Figure 2d-1] Shows a further step of the fabrication method according to the present invention. [Figure 2d-2] Shows a further step of the fabrication method according to the present invention. [Figure 2e] Shows a further step of the fabrication method according to the present invention. [Figure 2f] Shows a further step of the fabrication method according to the present invention. [Figure 2g] Shows a further step of the fabrication method according to the present invention. Mode for Carrying Out the Invention

[0013] (Detailed Description of the Invention) The figures are schematic diagrams not drawn to scale for readability. In particular, layer thicknesses along the z-axis are not to constant scale relative to lateral dimensions along the x-axis and y-axis, and the relative thicknesses of layers with respect to each other are not necessarily considered in the drawings.

[0014] The present invention relates to a method for fabricating a composite structure 100 (Figure 1) comprising a thin layer 1 made of single-crystal silicon carbide (hereinafter referred to as c-SiC to mean single-crystal silicon carbide) disposed on a silicon carbide support substrate 20. The support substrate 20 is polycrystalline (p-SiC).

[0015] The method first includes step a) providing an initial substrate 10 made of single-crystal silicon carbide (Figure 2a). The initial substrate 10 is preferably in the form of a wafer having a diameter of 100 mm, 150 mm, 200 mm, or 300 mm and a thickness typically of 300 to 800 microns. It has a front surface 10a and a back surface 10b. The surface roughness of the front surface 10a is preferably selected to be less than 1 nm Ra (average roughness) by measuring with an atomic force microscope (AFM) with, for example, a 20 micron × 20 micron scan. The initial substrate 10 may be 4H or 6H polytype and may have n-type or p-type doping.

[0016] Step a) also includes providing a carrier substrate 20 made of polycrystalline silicon carbide having a front surface 20a and a back surface 20b (Figure 2a).

[0017] The carrier substrate 20 can be manufactured by conventional techniques such as sintering or chemical vapor deposition. Preferably, it is identical in form to the initial substrate 10, and typically a wafer having the typical diameter and thickness described above with respect to the initial substrate 10. The surface roughness of the front surface 20a of the carrier substrate 20 is preferably selected to be less than 1 nm Ra, at least if this surface is intended to be directly bonded in a subsequent step d) of the method.

[0018] Next, the method includes a porosity-forming step b) applied to the initial substrate 10 to form the porous layer 11 (Figure 2b). The porous layer 11 can be formed by applying known porosity-forming methods for SiC to the initial substrate 10, some of which are described or referenced in publications by Y. Shishkin et al. ("Photoelectrochemical etching of n-type 4H silicon carbide", Journal of Applied Physics 96, 2311, 2004) and Gautier et al. ("Electrochemical formation of porous silicon carbide for micro-device applications", Materials Science Forum, ISSN: 1662-9752, Vol. 924, pp. 943-946, 2018).

[0019] Preferably, the porous layer 11 has a thickness of 0.5 μm to 5 μm, a porosity of 10% to 70%, and a pore size of typically 1 nm to 50 nm.

[0020] These properties are, firstly, advantageous for crystallization (step e)) in contact with the porous layer 11 of the layer 21 made of amorphous silicon carbide in single-crystal form, which is intended to form a thin layer 1 of the composite structure 100; and secondly, the properties of the porous layer 11 are suitable for enabling and facilitating separation within this layer in step f) of the method, while providing sufficient mechanical strength during the previous step.

[0021] The next step c) of the manufacturing method according to the present invention corresponds to forming surface layers 21 and 12 made of amorphous silicon carbide on at least the front surface 20a of the support substrate 20 or the front surface 10a of the initial substrate 10.

[0022] According to the first embodiment, the substrate 20 has the surface layer 21 made of amorphous silicon carbide (a-SiC) provided on at least its front surface 20a (Figure 2c).

[0023] According to the second embodiment, the surface layer 12 made of amorphous silicon carbide is formed at least on the front surface 10a of the initial substrate 10, that is, on the porous layer 11 (Figure 2c-1).

[0024] According to the third embodiment, a surface layer 21 is formed on the front surface 20a of the carrier substrate 20, and another surface layer 12 is formed on the porous layer 11 and is itself placed on the initial substrate 10.

[0025] In one or the other of the embodiments described above, the surface layers 21 and 12 may also be formed on the back surfaces 20b and 10b of the substrates 20 and 10.

[0026] Regardless of the embodiment, the surface layers 21 and 12 preferably have a total thickness of 10 μm or less.

[0027] To form these surface layers 21, 12, step c) includes depositing an a-SiC layer on the substrates 20, 10 according to the first modified form. The deposition of amorphous SiC can be carried out by chemical vapor deposition (CVD) techniques, such as plasma-enhanced CVD (PECVD) or direct liquid injection CVD (DLI-CVD), by physical vapor deposition techniques, or by any other known technique. In the case of CVD deposition, a deposition temperature of less than 1100°C or less than 1000°C is preferred, and with respect to the deposition precursor (methane or silane chemistry), a C / Si ratio of 1 or more is preferentially selected.

[0028] The aforementioned deposition techniques enable the formation of surface layers 21 and 12, whose thickness can vary typically from 100 nm to 10 μm, for example, about 1 μm. Similarly, the doping of the a-SiC surface layers 21 and 12 can be easily controlled when they are formed by one of these techniques. In particular, they may be highly doped (usually n-type, but optionally p-type), for this reason, 10 19 / cm 3 exceeding, or 10 20 / cm 3It contains dopant species at concentrations exceeding [amount]. It should be noted that the surface layers 21 and 12 are intended to crystallize at least partially in single-crystal form to form a thin layer 1 of the composite structure 100, and therefore may be highly doped to produce a thin layer 1 with low resistivity, depending on the requirements of the intended application.

[0029] According to the second modified form, step c) includes amorphousizing the surface layer of the substrate in order to form surface layers 21, 12 made of a-SiC. This amorphousization can be carried out by known techniques such as ion bombardment (e.g., by Si or C ions) or neutron bombardment, using appropriate energy to form amorphous layers 21, 12 having the desired thickness.

[0030] In the case of amorphous formation of the surface layer of the substrate 20 (the first and third embodiments), the polycrystalline structure of the support substrate 20 may be made amorphous, for example, by ion bombardment.

[0031] According to this second variant of the formation of surface layers 21 and 12, the thickness of the surface layer is preferably less than 1 μm, typically around 100 to several hundred nanometers.

[0032] The manufacturing method according to the present invention then includes step d) joining the initial substrate 10 and the carrier substrate 20 at their respective front surfaces 10a and 20a (Figures 2d, 2d-1, and 2d-2).

[0033] Therefore, in the first embodiment (Figure 2d), the porous layer 11 and the surface layer 21 are joined along the bonding interface 3, and the first intermediate structure 30 is obtained.

[0034] In the second embodiment (Figure 2d-1), the surface layer 12 is bonded to the carrier substrate 20 along the bonding interface 3', thereby obtaining the first intermediate structure 30'.

[0035] Finally, in the third embodiment (Figure 2d-2), the surface layers 22 and 12 formed on the carrier substrate 20 and the porous layer 11, respectively, are joined along the bonding interface 3'' to obtain the first intermediate structure 30''.

[0036] Regardless of the embodiment, as specified below, the bonding interfaces 3, 3', 3'' in step d) may include direct contact between the bonded surfaces or indirect contact between the bonded surfaces via a bonding layer.

[0037] The bonding in step d) is based on direct bonding by molecular adhesion. As is well known, such bonding does not require adhesive material because bonding occurs at the atomic level between the surfaces to be bonded. There are several types of molecular adhesive bonding that differ particularly in terms of temperature, pressure, atmospheric conditions or treatment before the surfaces are brought into contact. These include room temperature bonding with or without pre-plasma activation of the surfaces to be bonded, atomic diffusion bonding (ADB), surface-activated bonding (SAB), etc.

[0038] The bonding step d) may include a conventional sequence of chemical cleaning (e.g., RCA cleaning) and surface activation (e.g., by oxygen or nitrogen plasma) or other surface preparation (e.g., scrubbing) before bringing the surfaces to be bonded into contact, which is likely to improve the quality of the bonding interfaces 3, 3', 3'' (low defect density, high adhesion energy).

[0039] As described above, and optionally, step d) includes forming a bonding layer on one and / or the other surface of the substrates 20, 10 before bringing the surfaces to be bonded into contact. Thus, the bonding layer may be deposited (e.g., by chemical vapor deposition CVD) on the porous layer 11 and / or surface layer 21 (in the first embodiment), directly on the carrier substrate 20 and / or on the surface layer 12 (in the second embodiment), or on one and / or the other surface layer 22, 12 (in the third embodiment).

[0040] The bonding layer may consist of at least one material selected from silicon, nickel, titanium, tungsten, etc. The bonding layer is preferably thin, typically with a total thickness of 10 nm or less, or 5 nm or less. In the first embodiment, it is important that the bonding layer has a small thickness that allows for segmentation or dissolution in the form of nodules during the heat treatment of the subsequent step e), thereby resulting in at least local direct contact between the porous layer 11 and the surface layer 21, which is essential for the precise implementation of crystallization carried out in the next step e). If the bonding layer is made of a semiconductor material (particularly silicon, etc.), it can be doped to promote perpendicular electrical conductivity.

[0041] As shown in Figure 2d, in the first embodiment of the present invention, the first intermediate structure 30 resulting from step d) starts from the carrier substrate 20 and is therefore in the reverse order of the order shown in the figure. A support substrate 20 made of polycrystalline silicon carbide having a back surface 20b, The surface layer 21 made of amorphous silicon carbide on the front surface 20a side of the support substrate 20, A porous layer 11 that is in direct contact with the surface layer 21 or arranged via a bonding layer, wherein a bonding interface 3 exists between the porous layer 11 and the surface layer 21. An initial substrate 10 made of single-crystal silicon carbide, which is on the porous layer 11 and in contact with the porous layer 11. It is equipped with.

[0042] Figure 2d-1 shows the first intermediate structure 30' resulting from step d) in a second embodiment of the present invention, where the first intermediate structure 30' is A support substrate 20 made of polycrystalline silicon carbide, A surface layer 12 made of amorphous silicon carbide, which is in direct contact with the front surface 20a side of the support substrate 20 or is disposed via a bonding layer, wherein a bonding interface 3' exists between the support substrate 20 and the surface layer 12, The porous layer 11 on the surface layer 12, An initial substrate 10 made of single-crystal silicon carbide, which is on the porous layer 11 and in contact with the porous layer 11. It is equipped with.

[0043] Finally, Figure 2d-2 shows the first intermediate structure 30'' resulting from step d) in a third embodiment of the present invention, where the first intermediate structure 30'' is A support substrate 20 made of polycrystalline silicon carbide, The surface layer 21 made of amorphous silicon carbide on the front surface 20a side of the support substrate 20, Another surface layer 12 made of amorphous silicon carbide, which is in direct contact with or positioned via a bonding layer to the surface layer 21, and a bonding interface 3'' exists between the two surface layers 21 and 12. The porous layer 11 on the surface layer 12, An initial substrate 10 made of single-crystal silicon carbide, which is on the porous layer 11 and in contact with the porous layer 11. It is equipped with.

[0044] The next step (e) of this fabrication method includes a heat treatment applied to the first intermediate structures 30, 30', and 30'' at a temperature exceeding 900°C to crystallize the surface layers 21 and 12 (Figure 2e). The heat treatment temperature is preferably 1000°C or higher, or 1400°C or higher, or even 1850°C or higher. For example, a heat treatment at 1700°C for 30 minutes may be applied to 1 μm thick surface layers 21 and 12 made of a-SiC.

[0045] The surface layers 21 and 12 crystallize in the form of single-crystal silicon carbide by solid-phase epitaxy, starting from the direct contact interface between the porous layer 11 (this SiC has a single-crystal structure) and the surface layers 21 and 12 made of a-SiC. The surface layers that have crystallized in single-crystal form a thin layer 1.

[0046] In some cases, only a portion of the surface layers 21 and 12 may crystallize in a single-crystal form. This is because crystallization can begin at the contact interface with the support substrate 20 and occur at least partially in the form of polycrystalline silicon carbide, then the intermediate layer 22 is formed, and the p-SiC of the support substrate 20 extends to the thin layer 1 made of c-SiC. In other words, the intermediate layer 22 is interposed between the support substrate 20 and the thin layer 1. The interface between the intermediate layer 22 and the thin layer 1 has the advantage of being completely closed because it is defined by contact between the c-SiC and the pre-crystallization portion of the p-SiC from the same a-Si material (surface layers 21 and 12). This is an interesting advantage compared to bonding interfaces between two materials with different crystalline properties (e.g., p-SiC / c-SiC), and its complete closure depends particularly on the roughness and surface finish of the materials before bonding.

[0047] To obtain such an intermediate layer 22, in particular when there is no surface layer 21 on the carrier substrate 20 (i.e., in the second embodiment), preparation is made in the absence of a bonding layer, or by using a bonding layer that forms a set of nodules between which the carrier substrate 20 is in direct contact with the surface layer 12, such that the surface layer 12 made of a-Si (porous layer 11 side) is in direct contact with the carrier substrate 20.

[0048] Step e) leads to obtaining a second intermediate structure 40 in which all or part of the surface layers 21, 12 are crystallized in single-crystal form to form a thin layer 1, regardless of the embodiment being implemented (Figure 2e).

[0049] The fabrication method finally includes step f) separating the composite structure 100 on one hand and the remaining portion 10' of the initial substrate on the other hand within the porous layer 11 of the second intermediate structure 40 (Figure 2f).

[0050] Separation step f) is performed by applying mechanical stress to the second intermediate structure 40. The stress may be applied by pressing and / or inserting a tool (e.g., a blade or other inclined shape) onto the edge of the intermediate structure 40 opposite to the porous layer 11. Alternatively, the mechanical stress may be applied by a water jet or air jet directed onto the edge of the structure 40, also opposite to the porous layer 11. Regardless of the separation technique used, the applied mechanical stress must be suitable for propagating fracture waves within the porous layer 11, which has lower mechanical strength compared to other layers or interfaces of the second intermediate structure 40.

[0051] By taking care to protect the free surfaces of the second intermediate structure 40, separation can be optionally facilitated by lateral chemical etching of the porous layer 11.

[0052] At the end of separation step f), the free surface 1a of the thin layer 1 of the composite structure 100 may have a porous layer residue 11r (Figure 2f), similar to the front surface 10'a of the remaining portion 10' of the initial substrate.

[0053] Therefore, the method according to the present invention may include step g) mechanical and / or chemical treatment of the composite structure 100 in order to remove residue 11r of the porous layer 11 from the front surface 1a of the thin layer 1 and / or to correct the thickness uniformity of the composite structure 100 (Figure 2g).

[0054] Step g) may include chemical mechanical polishing (CMP) and / or chemical or plasma treatment (etching or cleaning) and / or mechanical treatment (grinding) to remove the residue 11r.

[0055] Step g) may also include cleaning operations of Caro (Piranha etching) and / or SC1 / SC2 (Standard Clean 1, Standard Clean 2) and / or HF (hydrofluoric acid) type, or N2, Ar, or CF4 plasma, in order to further improve the quality of the free surface 1a of the thin layer 1.

[0056] Step g) may include a treatment applied to the composite structure 100 at a temperature of 1000°C to 1900°C for about 1 hour to several hours. This heat treatment can be performed before or after the mechanical and / or chemical treatments described above. Its purpose is to stabilize the composite structure 100 by significantly developing the crystalline quality of the thin layer 1, where appropriate, so that the structure 100 is fully compatible with subsequent heat treatments at very high temperatures required for the fabrication of the components on and / or within the layer 1.

[0057] Finally, the fabrication method may include a step of readjusting the remaining portion 10' of the initial substrate for reuse as the initial substrate 10 of a new composite structure 100 (Figure 2g). Mechanical and / or chemical treatments similar to those applied to the composite structure 100 to remove residue 11r may be applied to the front surface 10'a of the remaining substrate 10'. The readjustment step may also include one or more treatments of the edges of the remaining substrate 10' and / or its back surface 10'b by chemical mechanical polishing, grinding, and / or dry or wet chemical etching.

[0058] Naturally, the present invention is not limited to the embodiments and examples described, and additional modified embodiments may be added without departing from the scope of the invention as defined by the claims.

Claims

1. A method for fabricating a composite structure (100) including a thin layer (1) made of single-crystal silicon carbide, which is placed on a support substrate (20) made of polycrystalline silicon carbide, a) Providing an initial substrate (10) made of single-crystal silicon carbide having a front surface (10a) and a back surface (10b), and a support substrate (20) made of polycrystalline silicon carbide having a front surface (20a) and a back surface (20b), b) A porosizing step applied to the initial substrate (10) in order to form a porous layer (11) at least on the front surface (10a) side of the initial substrate (10), c) The step of forming a surface layer (21, 12) made of amorphous silicon carbide on the front surface (20a) and / or the porous layer (11) of the carrier substrate (20), d) A step in which the initial substrate (10) and the carrier substrate (20) are joined at their respective front surfaces to manufacture a first intermediate structure (30, 30', 30''), e) A heat treatment step applied to the first intermediate structure (30, 30', 30'') at a temperature exceeding 900°C to form the thin layer (1), starting from the contact interface with the porous layer (11) in order to crystallize the surface layers (21, 12) at least partially in the form of single-crystal silicon carbide, thereby producing a second intermediate structure (40); f) Separating the second intermediate structure (40) within the porous layer (11) in order to obtain the composite structure (100) on one side and the remaining portion (10') of the initial substrate on the other side. Methods that include...

2. The method for manufacturing according to claim 1, wherein at the end of step b), the porous layer (11) has a thickness of 0.5 μm to 5 μm.

3. The method for manufacturing according to claim 1 or 2, wherein at the end of step b), the porous layer (11) contains pores, the size of which is 1 nm to 50 nm, and the degree of porosity is 10% to 70%.

4. The method for manufacturing according to claim 1 or 2, wherein at the end of step c), the surface layer (21, 12) has a thickness of 10 μm or less.

5. The method for manufacturing according to claim 1 or 2, wherein at the end of step c), the surface layer (21, 12) has a thickness of 1 μm or less, typically about 100 to several hundred nanometers.

6. A method for manufacturing according to claim 1 or 2, wherein step c) comprises depositing an amorphous silicon carbide layer on at least the front (20a) side of the carrier substrate (20) and / or on at least the porous layer (11) in order to form the surface layers (21, 12).

7. The deposited amorphous silicon carbide layer is highly doped, 10 １９ / cm ３ exceeding, or 10 ２０ / cm ３ A method for producing according to claim 6, having a concentration of dopant species exceeding the above.

8. The method for manufacturing according to claim 1 or 2, wherein step c) includes amorphousizing at least the front (20a) side surface layer of the carrier substrate (20) in order to form the surface layer (21).

9. Step d) includes forming a bonding layer on the front side of one and / or the other of the substrates before the step of joining the initial substrate (10) and the carrier substrate (20), A method for manufacturing the product according to claim 1 or 2, wherein the bonding layer has a total thickness of 10 nm or less after bonding.

10. The method for manufacturing according to claim 9, wherein the bonding layer is composed of at least one material selected from silicon, nickel, titanium, and tungsten.

11. The method for manufacturing according to claim 9, wherein during step e), the binding layer is segmented into nodules or dissolved to enable at least locally direct contact between the surface layer (21) and the porous layer (11) or between the surface layer (12) and the carrier substrate (20).

12. The method for manufacturing according to claim 1 or 2, wherein the heat treatment in step e) is performed at a temperature of 1000°C or higher, preferably 1400°C or higher, or 1850°C or higher.

13. The method for manufacturing according to claim 1 or 2, wherein in step e), the crystallization of the surface layer (21, 12) occurs at least partially in the form of polycrystalline silicon carbide, starting from the contact interface with the carrier substrate (20) to form the intermediate layer (22).

14. A method for manufacturing according to claim 1 or 2, further comprising a finishing step g) after step f), which includes mechanical and / or chemical treatment of the composite structure (100) to remove any residue (11r) of the porous layer (11) from the front surface (1a) of the thin layer (1) and / or to correct the thickness uniformity of the composite structure (100).

15. The method for manufacturing according to claim 14, wherein step g) includes a heat treatment applied to the composite structure (100) at a temperature of 1000°C to 1900°C before or after the mechanical and / or chemical treatment.

16. A method for manufacturing according to claim 1 or 2, comprising the step of readjusting the remaining portion (10') of the initial substrate for reuse as an initial substrate (10) for manufacturing a new composite structure (100).

17. A support substrate (20) made of polycrystalline silicon carbide, The carrier substrate (20) has at least one surface layer (21, 12) made of amorphous silicon carbide, which is positioned on the front (20a) side. A porous layer (11) is disposed on the aforementioned surface layer (21, 12), The initial substrate (10) made of single-crystal silicon carbide on the porous layer (11) and Equipped with, The porous layer (11) is in direct contact with the surface layer (21), or is arranged via a bonding layer, and the bonding interface (3) exists between the porous layer (11) and the surface layer (21), or The surface layer (12) is in direct contact with the carrier substrate (20) or is disposed via a bonding layer, and a bonding interface (3') exists between the carrier substrate (20) and the surface layer (12), or The surface layer (12) on the porous layer (11) side is in direct contact with another surface layer (21) on the carrier substrate (20) side, or is arranged via a bonding layer, and a bonding interface (3'') exists between the two surface layers (21, 12). Intermediate structure (30, 30').

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