Method for manufacturing a composite structure including a single-crystal thin film transferred onto a supporting substrate

Abstract

The invention relates to a method for manufacturing a composite structure comprising a thin layer of single-crystal material disposed on a support substrate, the manufacturing method comprising the following steps: a) supplying a wafer having two faces and being obtained from a blank mechanically ground by removal of a thickness less than or equal to 100 micrometers at two faces of the blank; b) preparing the support substrate from the wafer, involving mechanical and / or chemical treatment of the two faces of said wafer; the support substrate having two faces;c) measuring at least one curvature parameter of the wafer or substrate, and selecting: - from the two faces of the wafer, the one exhibiting a negative arc, so that it corresponds to a front face of the substrate after step b), or - from the two faces of the substrate, the one exhibiting a negative arc, so that it corresponds to a front face of the substrate; d) transferring the thin film onto the front face of the substrate to obtain the composite structure. Figure to be published with the abbreviation: No figure;

Description

Title of the invention: Method for manufacturing a composite structure comprising a single-crystal thin film transferred onto a support substrate. FIELD OF THE INVENTION

[0001] The present invention relates to the field of semiconductor materials for microelectronic components. It relates in particular to a method for manufacturing a composite structure comprising a single-crystal thin film transferred onto a support substrate, said composite structure having a low curvature. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Silicon carbide (SiC)-based composite structures, comprising a thin layer of monocrystalline SiC (m-SiC) deposited on a polycrystalline SiC (p-SiC) support substrate, are particularly attractive for the development of power components. The high-quality m-SiC thin layer enables the fabrication of high-performance components. The p-SiC support substrate reduces material costs compared to a bulk monocrystalline substrate and can provide additional functionalities and performance benefits, particularly related to its mechanical, electrical, and / or thermal properties.

[0003] Of course, many composite structures, other than the aforementioned m-SiC / p-SiC, can also be envisaged, with different single-crystal materials for the thin layer and different single- or polycrystalline materials for the supporting substrate.

[0004] A well-known thin-film transfer solution is the Smart Cut™ process, which involves implanting light ions to form a brittle plane embedded in a single-crystal donor substrate, and bonding the single-crystal donor substrate to a support substrate by direct gluing at a bonding interface. Separation is achieved, by thermal and / or mechanical activation, along the embedded brittle plane, leading to the transfer of a thin layer of single-crystal material from the donor substrate onto the support substrate.

[0005] Returning to the example of a SiC composite structure, curvature (aimed at being as low as possible) is more complex to control on p-SiC support substrates compared to m-SiC substrates. Thus, polycrystalline SiC substrates usually exhibit non-zero curvatures, quantified by parameters such as bow and warp, respectively known by their Anglo-Saxon terminology. As a reminder, bow corresponds to the deviation of the central point of the median surface of the measured wafer (which is (free, unsupported or fixed on a support plate) relative to a reference plane established by three uniformly spaced points on a circle whose diameter is smaller by a specified value than the diameter of the measured wafer. The median surface is defined by the points on the wafer equidistant from the two faces. The warp represents the difference between the maximum and minimum distances of the wafer's (free) median surface from the reference plane P. The warp value is usually greater than the arc value because the wafer's curvature rarely follows a uniform profile.

[0006] In practice, it is difficult (at a competitive cost) to obtain p-SiC support substrates, especially with a high level of doping (required for power electronics applications), with a deformation of less than 150 micrometers, for a wafer diameter of 150mm.

[0007] However, it is important to control and minimize the deformation (curvature) of composite structures to ensure their compatibility with subsequent manufacturing stages of microelectronic components. The maximum desired deformation value for a composite structure with a diameter of 150 mm is typically 100 micrometers.

[0008] SUBJECT OF THE INVENTION

[0009] The present invention proposes a method for manufacturing a composite structure including a single-crystal thin film transferred onto a support substrate: the curvature characteristics of the support substrate make it possible to define the face on which the thin film will be placed, in order to minimize the curvature of the composite structure.

[0010] BRIEF DESCRIPTION OF THE INVENTION

[0011] The invention relates to a method for manufacturing a composite structure comprising a thin layer of single-crystal material disposed on a support substrate, the manufacturing method comprising the following steps:

[0012] a) the supply of a wafer having two faces and originating from a raw disc mechanically ground by removal of a thickness less than or equal to 100 micrometers at the level of two faces of the raw disc;

[0013] b) the preparation of the support substrate from the wafer, involving mechanical and / or chemical treatment of both faces of said wafer; the support substrate having two faces;

[0014] c) the measurement of at least one curvature parameter of the wafer or substrate support, and the selection:

[0015] - among the two faces of the plate, the one presenting a negative arc, so that it corresponds to a front face of the support substrate at the end of step b), or

[0016] - among the two faces of the supporting substrate, the one presenting a negative arc, for that it corresponds to a front face of the supporting substrate;

[0017] d) the transfer of the thin layer onto the front face of the support substrate, to obtain the composite structure.

[0018] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: - in which the plate is formed from a polycrystalline material; - Step a) includes the following sub-steps: a) chemical vapor deposition of a layer formed from the polycrystalline material onto a growth substrate, a2) the removal of the growth substrate to obtain the raw disk; - at the end of sub-step a2), a sub-step a3) of mechanical rectification is applied, in the same way, to both faces of the raw disc; - a heat treatment at a temperature above 1550°C, or even above 1700°C, in particular at 1850°C, is applied between step a1) and step a2), or after step a2); - the wafer is formed from a material chosen from silicon carbide, aluminium nitride or silicon; - the single-crystal material is chosen from silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), diamond, silicon, germanium, indium phosphide (InP); - the arc of the wafer, measured on the side of its concave profile face, is between -100 micrometers and 0 micrometers for a wafer diameter of 150mm or 200mm; - the arc of the support substrate, measured on the side of its concave profile face, is between -80 micrometers and 0 micrometers for a support substrate diameter of 150mm or 200mm; - during the preparation of the support substrate in step b), a similar treatment is applied to both sides of the wafer; - during the preparation of the support substrate in step b), a different treatment is applied to each of the faces of the wafer, the residual stress state remaining similar on both faces of the support substrate at the end of step b); - a heat treatment at a temperature above 1550°C, or even above 1700°C, in particular at 1850°C, is applied to the wafer after step a) and / or to the substrate support during or at the end of step b); - a laser marking step is applied to the face of the support substrate having a convex profile; - The manufacturing process also includes the following step: e) the formation of microelectronic components on and / or in the thin layer of the composite structure. BRIEF DESCRIPTION OF THE FIGURES

[0019] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which:

[0020] [Fig. la]

[0021] [Fig.lb] Fig. aa and Fig.lb present composite structures that can be produced by the manufacturing process according to the invention;

[0022] [Fig.2a]

[0023] [Fig.2b]

[0024] [Fig.2c] Figures [Fig.2a], [Fig.2b], and [Fig.2c] present an embodiment of step a) of a manufacturing process according to the invention;

[0025] [Fig. 3] [Fig. 3] shows step b) of a manufacturing process conforming to the invention;

[0026] [Fig.4a]

[0027] [Fig. 4b] Figures [Fig. 4a] and [Fig. 4b] show step c) of a manufacturing process in accordance with the invention;

[0028] [Fig.5a]

[0029] [Fig.5b]

[0030] [Fig.5c]

[0031] [Fig.5c']

[0032] [Fig.5c]

[0033] [Fig.5d] Figures 5a, 5b, 5c, 5c', 5c”, 5d present sub-steps of step d) of a manufacturing process according to the invention;

[0034] [Fig. 6] Fig. 6 shows measurements of bow and warp " made on different support substrates and on the resulting composite structures; some composite structures were manufactured according to a process in accordance with the invention.

[0035] The same reference numerals in the figures may be used for elements of the same type. Some figures are schematic representations which, for the sake of clarity, are not drawn to scale. In particular, the layer thicknesses along the z-axis are not to scale with respect to the lateral dimensions along the x and y axes; and the relative thicknesses of the layers with each other are not necessarily to scale in the figures or between figures. Furthermore, some schematic representations do not depict the arc and deformation of the substrates. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention relates to a method for manufacturing a composite structure 100 comprising a thin layer 10 of monocrystalline material disposed on a support substrate 20. The thin layer 10 can be in direct contact with the support substrate 20 ([Fig. 1a]), or indirectly, via an intermediate layer 30 ([Fig. 1b]). As is usually the case in the semiconductor industry, the composite structure 100 is in the form of a circular wafer with a diameter, for example, 150 mm, 200 mm, or even larger. The support substrate 20 is advantageously made of a polycrystalline material, for economic reasons but also potentially to obtain specific mechanical, electrical, or thermal properties.

[0037] Preferably, the material composing the support substrate 20 is silicon carbide (SiC), aluminum nitride (Ni), silicon (Si), or another material. The single-crystal material can be chosen from silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), diamond, silicon, germanium, and indium phosphide (InP).

[0038] For power electronics applications, the intermediate layer 30 of the composite structure 100, if present, is advantageously formed of one or more metallic or semiconductor material(s).

[0039] The manufacturing process includes a first step a) of supplying a wafer 2 made of polycrystalline material. For a diameter of 150 mm or 200 mm, the thickness of the wafer 2 is typically between 400 µm and 3000 µm. The wafer 2 has two faces 2a, 2b which extend substantially parallel to a principal plane (x, y).

[0040] Several techniques exist for the fabrication or growth of polycrystalline materials in the form of discs, intended to form substrates or wafers ("wafers" according to Anglo-Saxon terminology), particularly for the semiconductor industry. Among these techniques are manufacturing by sintering, by PVT ("Physical Vapor Transport"), by CVD ("Chemical Vapor Deposition") or by HTCVD ("High Temperature Chemical Vapor Deposition"), etc.

[0041] The wafer 2 is derived from a blank 2' formed by one of the techniques mentioned and then mechanically rectified by removing a thickness less than or equal to 100 micrometers at the level of the two faces 2a',2b' of the blank 2'. A blank 2' often has different grain sizes or irregularities from one face to the other, which cause in particular problems of flatness (high thickness variation "TTV") and inhomogeneity of mechanical properties: this is why a material removal of the order of a few tens of micrometers, at the level of its two faces 2a',2b', is carried out.

[0042] Preferably, step a) comprises a substep a1) including chemical vapor deposition (CVD) of a layer 2” formed of the polycrystalline material onto a growth substrate 2c ([Fig. 2a]); a substep a2) of removing the growth substrate 2c then occurs to obtain the blank disk 2' ([Fig. 2b]). A substep a3) of mechanical grinding can then be applied to both faces of the blank disk 2', advantageously identically, to avoid introducing an asymmetry of residual stress between the faces of the resulting wafer 2 ([Fig. 2c]). This mechanical grinding aims in particular to remove a layer of highly stressed polycrystalline material (in tension or compression) comprising small grains, from the side where the blank disk 2' was in contact with the growth substrate 2c. Note that the diameter of the blank disk 2' can also be adjusted by contouring techniques.

[0043] Advantageously, a heat treatment at a temperature above 1550°C, or even above 1700°C, in particular at 1850°C, is applied between step a1) and step a2), or after step a2), in particular between step a2) and step a3), or even after step a3).

[0044] In the specific case where the polycrystalline material is SiC, the CVD technique involves a gaseous mixture comprising at least one silicon precursor gas (such as a silane or a chlorosilane) and / or at least one carbon precursor gas (such as an alkane or an alkene), and / or at least one silicon and carbon precursor gas (such as methyltrichlorosilane, abbreviated MTCS), and, if necessary, at least one dopant gas. These gases may be diluted in a carrier gas, which may be a reducing gas such as hydrogen and / or an inert gas such as argon. From this gaseous mixture, the 2" polycrystalline SiC layer forms on the 2c growth substrate. The latter is preferentially graphite, to form a 3C-SiC polytype. The reactor temperature during CVD deposition of SiC is typically between 1000°C and 1600°C.As an example, the deposition can be carried out on a graphite disk, 150 mm in diameter and approximately 2 mm thick, to ensure sufficient flatness of the growth substrate / p-SiC layer(s) assembly. The diameter and thickness of the 2c graphite disk can, of course, vary if one wishes to prepare a support substrate with a diameter of 100 mm, 200 mm, or other.

[0045] The graphite growth substrate 2c, coated with the p-SiC deposition layer 2'', is machined and then oxidized in air, typically at 900°C, to remove any graphite residue. It should be noted that the removal of graphite 2c could also be achieved using purely mechanical machining techniques or essentially by burning / oxidation. In practice, a raw p-SiC disk 2' is often recovered from each face of the growth substrate 2c. Mechanical grinding of the two faces 2a', 2b', inducing a removal of material on the order of a few tens of micrometers can then be carried out.

[0046] After its release from the growth substrate 2c, the raw disk 2' exhibits residual stresses related to the difference in coefficients of expansion between the growth substrate material 2c (for example graphite) and the polycrystalline material (for example SiC), as well as to the grain sizes varying from one face to the other of the disk 2'. These stresses are partially eliminated during the grinding of the disk 2'.

[0047] Returning to the general description of the invention, whatever the technique of manufacturing the raw disc 2', stresses generally remain in the plate 2, which are partially relaxed by the deformation of said plate 2: thus the latter usually has a non-zero curvature.

[0048] The manufacturing process according to the invention then comprises a second step b) corresponding to the preparation of the support substrate 20 from the wafer 2 ([Fig. 3]). This preparation includes a mechanical and / or chemical treatment of the faces 2a, 2b of said wafer 2. This treatment may, in particular, include mechanical grinding and / or chemical polishing and / or chemical etching, which are well known in the field of semiconductor substrates. The purpose of such treatment is to bring the wafer 2 to a target thickness (target thickness of the support substrate 20) and to produce a surface finish compatible with subsequent assembly by molecular bonding. The periphery of the wafer 2 may optionally be adjusted or reworked by contouring techniques to obtain the support substrate 20.

[0049] In a first advantageous embodiment, a similar treatment is applied to both faces 2a, 2b of the wafer 2 during the preparation of the support substrate 20 in step b). This treatment may include: - coarse grinding with a grinding wheel adapted to a high material removal rate, typically between a few tens of micrometers and a few hundred micrometers; for example, the mesh (or grit, according to Anglo-Saxon terminology) of the grinding wheel, the value of which varies inversely with the size of the abrasive grains, is less than 2000, typically between 100 and 1000; - fine grinding with a grinding wheel with a mesh size greater than or equal to 2000, for example between 2000 and 7000; the removal is typically between a few micrometers and a few tens of micrometers; - one or more mechano-chemical polishing(s) each inducing a removal of material of between a few tens of nanometers and a few micrometers.

[0050] One or more cleaning steps may be applied between the aforementioned thinning steps, particularly following polishing. Heat treatment in a temperature range of 1550°C or higher, or even higher than 1700°C, for example 1850°C, may also be applied to the insert before, after, or interspersed between the thinning steps.

[0051] Since the treatment applied to each of the faces 2a,2b of the plate 2 is similar, it is unlikely to introduce an asymmetry of stress between the faces 20a,20b of the support substrate 20. This avoids introducing an additional deformation or curvature.

[0052] In a second variant, the treatments applied to the faces of the wafer 2 are different, during the preparation of the support substrate 20 in step b). Nevertheless, attention will be paid to the fact that the two treatments induce a similar stress state on the two resulting faces 20a,20b of the support substrate 20.

[0053] Ensuring that the stress state induced by the treatments on each face 20a, 20b of the support substrate 20 is similar (typically less than 10% difference, or even less than 5%) limits the addition of stress asymmetry between the faces, and therefore additional deformation of the support substrate 20. A stress state at a face can be measured by Raman spectroscopy or transmission electron microscopy (TEM). Alternatively, the stress state related to the treatments applied to each face can be evaluated by the induced deformation, preferably kept below 100 μm, or even preferably below 50 μm.

[0054] At the end of step b), the support substrate 20 has a typical thickness of between 180 micrometers and 500 micrometers, in the case of a diameter of 150 mm or 200 mm. It also has a surface finish compatible with direct assembly (by molecular adhesion) onto another substrate. Such a surface finish typically corresponds to a roughness less than or equal to Inm RMS (measured by atomic force microscopy on scans typically ranging from 5 µm x 5 µm to 30 µm x 30 µm).

[0055] The manufacturing process according to the invention also includes a step c) corresponding to the measurement of at least one curvature parameter relating to the support substrate 20: this curvature measurement can be made either on the wafer 2, or on the support substrate 20.

[0056] The curvature parameter(s) can be measured using a confocal white light sensor which scans a surface of the substrate 2.20, the latter being placed on a support plane of the measuring tool, equipped with three support pins.

[0057] Equipment from the company E+H Metrology (MX 203-6-33, MX 203-58-37...) allows, for example, the non-contact measurement of geometric characteristics (TTV, bow, warp, etc.) of a wafer or substrate.

[0058] The curvature measurement can be performed at the end of step a), so as to identify, among the two faces 2a, 2b of the wafer 2, the one that presents a negative arc A. In other words, we seek to identify the face with a concave profile ([Fig. 4a]). This face, called the first face 21 of the wafer 2, is selected to correspond, at the end of step b), to the front face 20av of the support substrate 20. The other face, called the second face 22, is intended to correspond to the rear face 20ar of the support substrate 20 at the end of step b).

[0059] By way of example, the value of the arc A (“bow”) of a plate 2 of diameter 150mm or 200mm in p-SiC, measured on the side of the first face 21, is between -100qm and 0, for a plate thickness between 500qm and 700qm; the value of the deformation (“warp”) is between 0 and 150qm.

[0060] Note that, in the case where the arc is substantially equal to 0, either of the two faces 2a,2b of the plate 2 can correspond to the first face 21 and be intended to form a front face 20av of the future support substrate 20.

[0061] The curvature measurement can, alternatively or additionally, be carried out at the end of step b), so as to identify, among the two faces 20a, 20b of the support substrate 20, the one exhibiting a negative arc A, i.e., associated with a concave profile ([Fig. 4b]). This face, referred to as the first face 201 of the support substrate 20, is then selected to correspond to the front face 20av of the support substrate 20. The other face, referred to as the second face 202, then corresponds to the rear face 20ar.

[0062] By way of example, the value of the bow of a support substrate 20 of diameter 150mm or 200mm in p-SiC, measured on the side of the first face 201, is between -80qm and 0, for a substrate thickness between 250qm and 600qm; the value of the warp is between 0 and 130 micrometers.

[0063] Here again, in the case where the arc is substantially equal to 0, either of the two faces 20a,20b of the support substrate 20 can correspond to the front face 20av, which will receive the thin film 10 in the subsequent step of the process.

[0064] Thus, based on at least one parameter measured in step c), the method identifies the face of the wafer 2 or the support substrate 20 that has a concave profile (the first face 21,201) and, complementaryly, the face that has a convex profile (the second face 22,202). The first face 21,201 is selected to correspond to the front face 20av of the support substrate 20.

[0065] Optionally, a laser marking step is applied to the second face 202, opposite to the first face 201 of the support substrate 20 and corresponding to its rear face 20ar, for traceability purposes of the substrate 20 and the future composite structure 100.

[0066] The manufacturing process finally includes a fourth step d) of transferring a thin film 10 of a single-crystal material onto the front face 20av of the support substrate 20 (Figures 5a to 5d). Although any known thin-film transfer process can be used, particular reference can be made to the Smart Cut™ process, which involves the formation of a brittle plane embedded 11 in a donor substrate 1 of single-crystal material by ionic implantation of light species (e.g., H, He, or a combination of these two species) ([Fig. 5a], [Fig. 5b]). Direct assembly (by molecular adhesion) is performed between the implanted face of the donor substrate 1 and the front face 20av of the support substrate 20, defining a bonding interface 40, and forming a bonded assembly 50 ([Fig. 5c]).A separation in the buried fragile plane 11 then allows the transfer of a thin monocrystalline layer 10, from the donor substrate 1, onto the support substrate 20, giving rise to the composite structure 100, while preserving the remainder 1' of the donor substrate for future reuse ([Fig.5d]).

[0067] An intermediate layer 30 may optionally be formed on the donor substrate 1, on the support substrate 20 or on each of these two substrates, before assembly ([Fig.5c]', [Fig.5c]”): said intermediate layer 30 will be intercalated between the thin layer 10 and the support substrate 20 in the composite structure 100.

[0068] Finishing treatments, thermal, mechanical and / or chemical, are usually applied to the free surface 10a of the transferred thin film 10 in order to restore its high crystallographic quality and surface condition. Similar treatments can be applied to the free face l'a of the remainder 1' of the donor substrate for reuse.

[0069] By way of example, the thin film 10 of the composite structure 100 has a thickness ranging from a few tens of nm to a few hundred nm, for example, between 50 nm and 800 nm. Epitaxial steps can be carried out on said thin film 10, so as to thicken it (homoepitaxy) or to grow other materials (heteroepitaxy), for the needs of the electronic components to be manufactured. The thin film 10 has an electrical resistivity suitable for the application and the intended components.

[0070] Statistically, the amplitude of the deformation ("warp") of the composite structure 100 varies only slightly with respect to the deformation of the supporting substrate 20. This is particularly visible in the graph in [Fig. 6], where it can be seen that the deformation measured on a plurality of p-SiC supporting substrates is between 100 μm and 125 μm (substrates taken over a wide range of deformations for this test) and that the deformation measured on a plurality of composite structures (m-SiC / p-SiC) developed from said support substrates is between approximately 100m and 160pm.

[0071] A deformation greater than lOOqm is not desirable for a composite structure 100 because it generally leads to its downgrading.

[0072] Limiting the amplitude of the deformation of the support substrates 20 is not easy, as mentioned in the introduction. The applicant observed that, even with a deformation amplitude of the support substrate 20 in the upper range of values, it is possible to limit the resulting deformation of the composite structure 100 by selecting, as the front face 20av of the support substrate 20, the face exhibiting a negative arc. Surprisingly, it is therefore not the amplitude of the deformation ("warp") of the support substrate alone that determines the amplitude of the resulting deformation of the composite structure 100.

[0073] The group of support substrates 20, referenced as G1 in [Fig.6], has followed the manufacturing process according to the invention, with the application of step c) at the end of which the face having a concave profile (negative arc) is defined as the front face 20av (to be assembled) of the support substrate 20. The composite structures 100 according to the invention are included in group G2, whose deformation values ​​remain less than 100qm.

[0074] On [Fig.6], the points marked with a black cross illustrate support substrates 20 exhibiting high deformations, typically between 50qm and 125qm, and whose front face 20av is concave (arc between -40qm and -20qm): the resulting deformation of the composite structures 100 (points marked with a black cross in group G2) is between approximately 20qm and 90qm.

[0075] The manufacturing process according to the invention therefore makes it possible to obtain composite structures 100 with limited curvature (deformation less than 100qm), perfectly suited for the subsequent development of microelectronic components on and / or in the thin layer 10.

[0076] The process also allows the use of support substrates whose high deformation (typically greater than 75 µm) and positive arc (typically greater than 20 µm) measured on the side of an initial front face would be incompatible with obtaining a composite structure 100 in specification. By applying step c) of curvature measurement, the initial front face, with a convex profile, is defined as the second face 202 of the support substrate 20, corresponding to the rear face 20ar; the initial rear face of the substrate, with a concave profile, is defined as the first face 201 corresponding to the front face 20av to be assembled of the support substrate 20.

[0077] The composite structure 100 obtained from these support substrates, the front and rear faces of which have been requalified, thus exhibits a deformation of less than 100qm, in specification.

[0078] The manufacturing process may further include a step e) of forming microelectronic components on and / or in the thin film 10 of the composite structure 100. The components targeted, particularly high-voltage components, are for example Schottky diodes, MOSFET or HEMT transistors, and / or high-frequency (RF) components, etc. As mentioned previously, it may be necessary to increase the thickness of the thin film 10 to construct components operating at high voltage. Epitaxial growth can then be performed on the free face 10a of the thin film 10.

[0079] Of course, the invention is not limited to the embodiments and examples described, and alternative embodiments can be made without departing from the scope of the invention.

Claims

Demands

1. A method for manufacturing a composite structure (100) comprising a thin layer (10) of single-crystal material disposed on a support substrate (20), the manufacturing method comprising the following steps: a) supplying a wafer (2) having two faces (2a,2b) and originating from a blank (2') mechanically ground by removing a thickness less than or equal to 100 micrometers at two faces (2a',2b') of the blank (2'); b) preparing the support substrate (20) from the wafer (2), involving mechanical and / or chemical treatment of the two faces (2a,2b) of said wafer (2); the support substrate (20) having two faces (20a,20b);c) the measurement of at least one curvature parameter of the wafer (2) or of the support substrate (20), and the selection: - among the two faces (2a,2b) of the wafer (2), of the one presenting a negative arc, so that it corresponds to a front face (20av) of the support substrate (20) at the end of step b), or - among the two faces (20a,20b) of the support substrate (20), of the one presenting a negative arc, so that it corresponds to a front face (20av) of the support substrate (20); d) the transfer of the thin film (10) onto the front face (20av) of the support substrate (20), to obtain the composite structure (100).

2. A manufacturing method according to claim 1, wherein the wafer (2) is formed from a polycrystalline material.

3. A manufacturing process according to claim 2, wherein step a) comprises the following substeps: a1) chemical vapor deposition of a layer (2”) formed of the polycrystalline material, on a growth substrate (2c), a2) removal of the growth substrate (2c) to obtain the raw disc (2').

4. A manufacturing method according to claim 3, wherein, at the end of substep a2), a substep a3) of mechanical grinding is applied, in the same way, to both faces of the raw disc (2').

5. A manufacturing method according to any one of claims 3 and 4, wherein a heat treatment at a temperature above 1550°C, or even higher than 1700°C, especially up to 1850°C, is applied between step a1) and step a2), or after step a2).

6. A manufacturing method according to any one of the preceding claims, wherein the wafer (2) is formed from a material selected from silicon carbide, aluminum nitride or silicon.

7. A manufacturing process according to any one of the preceding claims, wherein the single-crystal material is selected from silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), diamond, silicon, germanium, indium phosphide (InP).

8. A manufacturing method according to any one of the preceding claims, wherein the arc (A) of the wafer (2), measured on the side of its face (2a,2b) with concave profile, is between -100 micrometers and 0 micrometers for a wafer diameter (2) of 150mm or 200mm.

9. A manufacturing method according to any one of the preceding claims, wherein the arc (A) of the support substrate (20), measured from the side of its face (20a,20b) with concave profile, is between -80 micrometers and 0 micrometers for a diameter of support substrate (20) of 150mm or 200mm.

10. A manufacturing method according to any one of the preceding claims, wherein, during the preparation of the support substrate (20) in step b), a similar treatment is applied to both faces (2a,2b) of the wafer (2).

11. A manufacturing method according to any one of claims 1 to 9, wherein, during the preparation of the support substrate (20) in step b), a different treatment is applied to each of the faces (2a, 2b) of the wafer (2), the residual stress state remaining similar on both faces (20a, 20b) of the support substrate (20) at the end of step HO

12. DJ. A manufacturing method according to any one of the preceding claims, wherein a heat treatment at a temperature above 1550°C, or even above 1700°C, in particular at 1850°C, is applied to the wafer (2) after step a) and / or to the support substrate (20) during or after step b).

13. A manufacturing method according to any one of the preceding claims, wherein a laser marking step is applied to the face (2a,2b) of the support substrate (20) having a convex profile. 15

14. A manufacturing method according to any one of the preceding claims, further comprising the following step: e) the formation of microelectronic components on and / or in the thin layer (10) of the composite structure (100).

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