METHOD FOR PRODUCING A HOMOEPITAXIAL SILICON CARBIDE LAYER, ALLOWING LIMITING THE FORMATION OF BPD-TYPE DEFECTS, AND ASSOCIATED COMPOSITE STRUCTURE

Abstract

The invention relates to a method for manufacturing an active layer of monocrystalline silicon carbide by homoepitaxy on a composite structure, the method comprising the following steps: 1) providing a composite structure comprising a growth layer of monocrystalline silicon carbide extending along a main plane and arranged on a support substrate, the growth layer being delimited by a peripheral periphery and having a first thickness along an axis normal to the main plane;2) the formation of a local barrier in or on the growth layer, the local barrier extending at a distance and along the peripheral periphery, and corresponding to a physical discontinuity of the growth layer chosen from: - a bump relief induced by the presence of a material on the growth layer, said material being different from that of the growth layer, - a hollow relief corresponding to an etched zone of the growth layer, or - an amorphous domain or one of crystallinity different from the rest of the growth layer, the local barrier having a thickness, along the axis normal to the principal plane, less than the first thickness; 3) the epitaxial growth of the active layer on the growth layer. Figure to be published with the abstract: no figure;

Description

Title of the invention: METHOD FOR PRODUCING A HOMOEPITAXIAL SILICON CARBIDE LAYER, MAKING IT POSSIBLE TO LIMIT THE FORMATION OF DEFECTS BPD TYPE, AND ASSOCIATED COMPOSITE STRUCTURE FIELD OF THE INVENTION

[0001] The present invention relates to the field of semiconductor materials, in particular composite structures comprising an active layer of silicon carbide (SiC) produced by homoepitaxy on a free SiC surface. It relates in particular to a manufacturing method making it possible to limit the formation of extensive defects of the basal plane dislocation (BPD) type and Shockley stacking faults (SSF) in said layer. It also relates to a composite structure on which an active layer of excellent quality can be homoepitaxied.

[0002] TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Silicon carbide (SiC) is a particularly interesting material for the manufacture of power devices, radio frequencies or even devices operating at very high temperatures. To develop these devices, it is usual to grow an active layer 150 of SiC (for example of polytype 4H or 6H) on the surface of a bulk substrate 1 (of monocrystalline SiC) or of a composite structure 100 including a thin layer 10 (of monocrystalline SiC) transferred onto a support substrate 20 (advantageously of polycrystalline or monocrystalline SiC of lower quality), as illustrated in [Fig.l]. A composite structure 100 can in particular be developed by a known thin layer transfer technique such as the Smart Cut™ process.

[0004] During the epitaxy of the active layer 150, certain defects (called initial defects) present on the surface of the bulk substrate 1 or of the thin layer 10 of the composite structure 100 can induce the formation of local inclusions of SiC 3C polytype or of disoriented SiC 4H zones. The stress field created by the local inclusions triggers the sliding of basal plane dislocations (BPD), giving rise to a complex network of Shockley stacking faults (SSF) and partial dislocations in the epitaxially grown active layer. These defects are very critical because they can, among other things, cause the deterioration of the devices subsequently produced in the active layer, by a bipolar degradation mechanism. In addition, each defect can easily extend by thermal activation and by recombination of electron-hole pairs, in a direction parallel to the epitaxial surface.This significantly worsens the situation, as multiple devices can be impacted by each widespread fault.

[0005] SUBJECT OF THE INVENTION

[0006] The present invention relates to a method for manufacturing an active layer of monocrystalline silicon carbide, by homoepitaxy, said method making it possible to limit the density of extended defects of the basal plane dislocation (BPD) and Shockley stacking faults (SSF) type in said layer. The manufacturing method comprises in particular a step of forming a peripheral local barrier on or in the growth layer of a composite structure, to prevent the extension of the inclusions generated in the active layer, into extended defects of the BPD and SSF type. The invention also relates to a composite structure provided with said local barrier.

[0007] BRIEF DESCRIPTION OF THE INVENTION

[0008] The invention relates to a method for manufacturing an active layer of monocrystalline silicon carbide by homoepitaxy on a composite structure, the method comprising the following steps:

[0009] 1) providing a composite structure comprising a growth layer in monocrystalline silicon carbide extending along a main plane and arranged on a support substrate, the growth layer being delimited by a peripheral periphery and having a first thickness along an axis normal to the main plane;

[0010] 2) the formation of a local barrier in or on the growth layer, the barrier local extending at a distance and along the peripheral perimeter, and corresponding to a physical discontinuity of the growth layer chosen from:

[0011] - a bumpy relief induced by the presence of a material on the growth layer, said material being different from that of the growth layer,

[0012] - a hollow relief corresponding to an engraved area of ​​the growth layer, or

[0013] - an amorphous domain or one with a crystallinity different from the rest of the layer of growth,

[0014] the local barrier having a thickness, along the axis normal to the main plane, less than the first thickness;

[0015] 3) epitaxial growth of the active layer on the growth layer, the layer active with a second thickness.

[0016] According to other advantageous and non-limiting characteristics of the invention, taken alone or in any technically feasible combination: • the first thickness is between 50nm and Ipm; • the peripheral edge of the growth layer is on average between 0.5mm and 2mm from the peripheral edge of the support substrate of the composite structure; • the local barrier is located more than 0.1 mm, more than 0.5 mm, more than 1 mm, more than 2 mm, more than 3 mm, or even more than 5 mm from any point on the peripheral edge of the growth layer; • the thickness of the local barrier is less than 70%, 50%, 30%, 20%, or even 10% of the first thickness; • the hollow relief is produced by mechanical abrasion, laser abrasion, wet engraving or dry engraving of the growth layer; • the amorphous domain or domain of crystallinity different from the rest of the growth layer is produced by laser amorphization or by ion implantation; • the bumpy relief is produced by local deposition of a material such as tungsten nitride or tungsten disilicide; • the second thickness is greater than or equal to 5 pm, 10 pm, or even 30 pm.

[0017] The invention further relates to a composite structure comprising a growth layer of monocrystalline silicon carbide extending along a main plane and arranged on a support substrate, the growth layer being delimited by a peripheral periphery and having a first thickness along an axis normal to the main plane; the composite structure is remarkable in that it comprises a local barrier in or on the growth layer, the local barrier extending at a distance and along the peripheral periphery, and corresponding to a physical discontinuity of the growth layer chosen from: - a bumpy relief induced by the presence of a material on the growth layer, said material being different from that of the growth layer, - a hollow relief corresponding to an engraved area of ​​the growth layer, or - an amorphous domain or one with a crystallinity different from the rest of the growth layer. The local barrier has a thickness, along the axis normal to the main plane, less than the first thickness.

[0018] According to other advantageous and non-limiting characteristics of the invention, taken alone or in any technically feasible combination: - the local barrier is located more than 0.1 mm, more than 0.5 mm, more than 1 mm, more than 2 mm, more than 3 mm, or even more than 5 mm from any point on the peripheral edge of the growth layer; - the thickness of the local barrier is less than 70%, 50%, 30%, 20% or even 10% of the first thickness; - the composite structure further comprises an active layer of monocrystalline silicon carbide grown by homoepitaxy on the growth layer, the active layer having a second thickness; - the second thickness is greater than or equal to 5pm, 10pm, or even 30pm. BRIEF DESCRIPTION OF THE FIGURES

[0019] Other characteristics and advantages of the invention will emerge from the detailed description of the invention which follows with reference to the appended figures in which:

[0020] [Fig.l] [Fig.l] shows a solid substrate, a composite structure with and without epitaxial layer;

[0021] [Fig.2] [Fig.2] shows an example of mapping the surface of a raw active layer on a composite structure; the dark areas correspond to extended defects (BPD network, SSF, partial dislocations);

[0022] [Fig.3] [Fig.3] shows an image of an extended defect, obtained by photoluminescence imaging: we can see at the bottom left of the image a jagged area (the black region being the crown of the composite structure, devoid of a growth layer), at the level of which an inclusion has caused an extended defect;

[0023] [Fig.4a]

[0024] [Fig.4b]

[0025] [Fig.4c]

[0026] [Fig.4d]

[0027] [Fig.4e] Figures 4a, 4b, 4c, 4d, 4e show sub-steps of manufacturing a composite structure in accordance with the method according to the invention;

[0028] [Fig.5] [Fig.5] shows an example of a local barrier formed on and / or in the growth layer of a composite structure, in accordance with the method according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention relates to a method for manufacturing an active layer 150 made of monocrystalline silicon carbide, by homoepitaxy on the growth layer 10 of a composite structure 100.

[0030] The applicant has observed that the extensive defects mentioned in the introduction, resulting from local inclusions formed during epitaxy on initial defects of the growth layer 10, become extremely significant for epitaxially grown active layers whose thickness is greater than 100 μm, or even very critical for thicknesses greater than 30 μm. In a composite structure 100, the initial defects may in particular correspond to: holes crossing the growth layer 10, induced by a local transfer problem, serrations around the edge of the growth layer, or local deformations of the growth layer.

[0031] [Fig.2] shows an example of mapping of defects detected on the surface of a 30 pm active layer grown on a composite structure 100: we note the very high density of extended defects, starting mainly from the periphery of the growth layer 10 and having propagated thermally towards the center of the structure. [Fig.3] presents an example of an inclusion from which a network of defects BPD and SSF propagated to generate an extensive defect. The image is obtained by photoluminescence microscopy. The black region at the bottom left of the image is devoid of growth layer 10, and we note the jagged appearance of the periphery 10c of growth layer 10. These jaggednesses, as stated above, constitute initial defects likely to give rise to local inclusions during epitaxial growth, and consequently, to extensive defects.

[0032] The method according to the invention aims to provide an active layer 150 of improved quality by implementing a local barrier 130 in the growth layer 10, capable of blocking the extension of BPD and SSF type defects; this local barrier is defined to take into account a specificity of the composite structures 100, namely that the growth layer 10 has an irregular peripheral periphery 10c, which is a major source of initial defects likely to give rise to extended killer defects after epitaxy of the active layer 150.

[0033] The first step of the method corresponds to the provision of a composite structure 100 comprising a growth layer 10 of monocrystalline silicon carbide extending along a main plane (x,y) and arranged on a support substrate 20. The composite structure 100 is preferably in the form of a circular plate (“wafer” according to English terminology) with a diameter of 100mm, 150mm, 200mm, or even more. It could nevertheless be in any other form allowing its subsequent processing for the manufacture of components. The thickness of the structure 100 extends along the z axis in the figures.

[0034] As indicated in the introduction, the composite structure 100 can be produced by a layer transfer technique such as the Smart Cut™ process.

[0035] In a first sub-step a), a donor substrate 1 made of monocrystalline silicon carbide and a support substrate 20 are provided ([Fig.4a]). The monocrystalline SiC can be of polytype 4H, 6H or 3C. The donor substrate 1 is preferably in the form of a wafer with a diameter identical to or very close to that of the support substrate 20 with which it will subsequently be assembled, and with a thickness typically between 300 qm and 800 qm. It has a front face 1a and a rear face 1b. The surface roughness of the front face 1a is advantageously chosen to be less than 1 nm RMS, or even less than 0.5 nm RMS, measured by atomic force microscopy (AFM) on a scan of 20 qm x 20 qm. The type of doping and the resistivity of the donor substrate 1 are defined according to the application and the devices targeted. The support substrate 20 corresponds to the mechanical support of the future composite structure 100.It is advantageously formed from polycrystalline silicon carbide (p-SiC) or monocrystalline SiC of lower crystalline quality. Its electrical properties (its type and level of doping) can also be chosen according to the intended application.

[0036] The second sub-step b) comprises the implantation of light species in a donor substrate 1, to form a buried fragile plane 11 delimiting, with a front face 1a of the donor substrate 1, the surface layer to be transferred 10' ([Fig.4b]). The light species are preferably hydrogen and / or helium, and are implanted in the donor substrate 1, at a depth consistent with the thickness of the targeted growth layer 10. These light species will form, around the determined depth, microcavities distributed in a thin layer parallel to the free surface 1a of the donor substrate 1, i.e. parallel to the (x,y) plane in the figures. This thin layer is called the buried fragile plane 11 for the sake of simplification. The implantation energy of the light species is chosen so as to reach the targeted depth.For example, hydrogen ions will be implanted at an energy between 10 keV and 250 keV, and at a dose between 5E16 / cm2 and 1E17 / cm2, to delimit a surface layer 10' having a thickness of the order of 100nm to 1500nm. Note that a protective layer may be deposited on the front face 1a of the donor substrate 1, prior to the ion implantation step. This protective layer may be composed of a material such as silicon oxide or silicon nitride for example. It may be removed prior to the following sub-step.

[0037] The third sub-step c) corresponds to the assembly of the support substrate 20, on the side of its front face 20a, with the implanted donor substrate 1, also on the side of its front face 1a ([Fig.4c]). The lateral dimensions in the main plane (x,y) of the support substrate 20 (its diameter in particular) are the same as those of the composite structure 100. The support substrate 20 has a thickness typically between approximately 50 qm and several hundred micrometers, for example between 50 qm and 650 qm, or between 100 qm and 450 qm, or between 200 qm and 350 qm.

[0038] The assembly is made by direct bonding, by molecular adhesion, along a bonding interface 40. Optionally, an intermediate layer can be formed on the front face 1a of the donor substrate 1, before or after the introduction of the light species, and in any case, before the assembly phase. This intermediate layer can be made of a dielectric, semiconductor or metallic material (such as for example silicon oxide, silicon, silicon carbide, tungsten, titanium, etc.). Optionally, an intermediate layer can also be deposited on the face 20a to be assembled of the support substrate 20, prior to the assembly; it can be chosen to be of the same nature or of a different nature from the intermediate layer mentioned for the donor substrate 1. An intermediate layer can optionally be deposited on either of the two substrates 1, 20 to be assembled.The intermediate layer(s) is (are) intended to be buried in the bonded assembly 50 after assembly, and ultimately, in the composite structure 100.

[0039] Direct bonding by molecular adhesion does not require an adhesive material, because Bonds are established at the atomic level between the assembled surfaces. Several types of molecular adhesion bonding exist, which differ in particular by their temperature, pressure, atmosphere or treatment conditions prior to bringing the surfaces into contact. Examples include room temperature bonding with or without prior plasma activation of the surfaces to be assembled, atomic diffusion bonding (ADB), surface-activated bonding (SAB), etc.

[0040] The assembly sub-step may comprise, prior to bringing the faces 1a, 20a to be assembled into contact, conventional sequences of cleaning by chemical means (for example, RCA cleaning), surface activation (for example, by oxygen or nitrogen plasma) or other surface preparations (such as cleaning by brushing), capable of promoting the quality of the bonding interface 40 (low defectivity, high adhesion energy).

[0041] It should be noted that the presence of a chamfer, at the peripheral edge 20c of the support substrate 20 and the peripheral edge of the donor substrate 1, generates a non-bonded peripheral crown (not shown in [Fig.4c]), crown in which the surface layer 10' will not be transferred.

[0042] The fourth sub-step d) corresponds to a separation along the buried fragile plane 11 to form an intermediate composite structure 100' comprising the surface layer 10' after transfer and the support substrate 20, on the one hand, and the remainder of the donor substrate 1', on the other hand ([Fig.4d]). The separation along the buried fragile plane 11 is usually carried out by applying a heat treatment at a temperature between 800°C and 1200°C. Such a heat treatment induces the development of cavities and microcracks in the buried fragile plane 11, and their pressurization by the light species present in gaseous form, until the propagation of a fracture along said fragile plane 11. Alternatively or jointly, a mechanical stress can be applied to the bonded assembly and in particular at the buried fragile plane 11, so as to propagate or help to mechanically propagate the fracture leading to the separation.

[0043] The free surface 10'a of the surface layer 10' is usually rough after separation: for example, it has a roughness of between 5nm and 100nm RMS. The surface layer 10' is delimited, in the (x,y) plane by a peripheral periphery 10'c, set back from the peripheral edge 20c of the support substrate 20. As mentioned previously, this peripheral periphery 10'c may be serrated and irregular; on average, it is spaced from the peripheral edge 20c by a distance (width of the non-bonded peripheral crown) of between 0.5mm and 2mm.

[0044] Finally, the fifth sub-step e) comprises the application of treatments thermal, mechanical and / or chemical to the free surface 10'a of the surface layer 10', to form the composite structure 100 provided with the growth layer 10 made of monocrystalline silicon carbide ([Fig.4e]). In particular, this sub-step e) may comprise a mechanical-chemical smoothing treatment of the free surface 10'a of the surface layer 10'. A removal for example of between 50nm and 300nm makes it possible to effectively restore the surface state of the layer, typically leading to a roughness less than or equal to 0.5nm RMS, or even less than or equal to 0.1nm RMS (AFM scan 10x10qm2 or 20x20qm2). Sub-step e) may also comprise at least one heat treatment at a temperature of between 1200°C and 1800°C. Such heat treatment is applied to remove residual light species from the surface layer 10' and to promote the rearrangement of its crystal lattice, thereby forming a high-quality growth layer 10.It also makes it possible to strengthen the bonding interface 40...

[0045] At this stage of the process, the growth layer 10 of the composite structure 100 has a first thickness typically ranging from a few tens of nm to a few hundreds of nm, for example, between 50 nm and 1000 nm. The growth layer 10 is delimited by a peripheral edge 10c having irregularities, such as serrations. Generally, said peripheral edge 10c is located, on average, between 0.5 mm and 2 mm from the peripheral edge 20c of the support substrate 20 of the composite structure 100.

[0046] The method according to the invention then comprises a second step corresponding to the formation of a local barrier 130 in or on the growth layer 10. This local barrier corresponds to a physical discontinuity of the growth layer 10, and extends remotely and continuously along the peripheral periphery 10c ([Fig.5] (i) (ii)). Preferably, it is located more than 0.1mm, more than 0.5mm, more than 1mm, or even more than 2mm, more than 3mm, or even more than 5mm from any point of the peripheral periphery 10c of the growth layer 10.

[0047] The barrier 130 can follow, in the main plane (x,y), the path of the peripheral contour 10c, or follow a substantially different path, for example more regular (perfectly circular) or more irregular, to bypass specific initial defects present in the immediate vicinity of the peripheral contour 10c of the growth layer 10.

[0048] According to a first embodiment, the physical discontinuity can result in a bumpy relief induced by the presence of a material placed on the growth layer 10, said material being different from that of the growth layer 10. Such a relief can for example be produced by local deposition of a material such as a tungsten nitride or a tungsten disilicide (WSi2).

[0049] According to a second embodiment, the physical discontinuity characterizing the local barrier 130 can be translated by a hollow relief, which can in particular be produced by mechanical abrasion (sawing, lapping), by laser abrasion, by wet etching or by dry etching of the growth layer 10, locally ([Fig.5] (ii) and (iii)).

[0050] Finally, according to a third embodiment, the physical discontinuity may correspond to an amorphous domain or one of crystallinity different from the rest of the growth layer 10, for example produced by laser amorphization or by ion implantation.

[0051] The local barrier 130 has a thickness, along a z axis normal to the main plane (x,y), less than the first thickness, in particular less than 70%, 50%, 30%, 20%, or even 10% of the first thickness. It has a width, in the main plane (x,y) and in a radial direction, which can vary between 0.1 and 1000 micrometers.

[0052] The applicant has identified that the aforementioned characteristics of the local barrier 130 make it possible to block the extension of basal plane dislocations (BPD) and Shockley stacking fault (SSF) networks from local inclusions of SiC 3C polytype or disoriented SiC 4H zones likely to form, during epitaxy, on the irregularities of the peripheral periphery 10c of the growth layer 10. The presence of this local barrier 130 thus prevents killer defects of the BPD and SSF type from extending from the periphery 10c towards the center of the growth layer 10, and makes it possible to obtain an active layer 150, after epitaxial growth, of high quality.

[0053] The physical discontinuity of the growth layer 10 that constitutes the local barrier 130 effectively prevents the propagation of BPD and SSF defects. Without being bound by this explanation, it is put forward that the thickness of the barrier 130, less than the thickness of the growth layer 10, is an important parameter to prevent the propagation of new radially extended defects, from said barrier 130.

[0054] The method according to the invention finally comprises a third step corresponding to the epitaxial growth of the active layer 150 on the growth layer 10, the active layer having a second thickness, typically greater than or equal to 5 pm, 10 pm, or even 30 pm.

[0055] This epitaxial growth of silicon carbide is carried out in the conventional temperature range, namely between 1500°C and 1900°C.

[0056] The physical discontinuity constituted by the local barrier 130 induces locally disturbed epitaxial growth: in particular, the barrier 130 extends into the thickness of the active layer 150, as it grows, in the form of a “wall” including stacking faults (SF), favorable to blocking the sliding of the BPD dislocations.

[0057] The disruption of epitaxial growth linked to barrier 130 nevertheless remains local and the rest of the active layer 150 grows according to the crystal structure of the growth layer 10.

[0058] In the example illustrated in [Fig.5] (iii) and (iv), the composite structure 100 provided in the first step of the method comprises a growth layer 10 made of c-SiC with a thickness of 600 nm, arranged on a support substrate 20 made of p-SiC with a thickness of 350 pm. The local barrier 130, produced during the second step of the method, corresponds to a hollow relief produced by local etching by mechanical abrasion: its depth is approximately 300 nm and its width is approximately 2 pm. It is located 1 mm from the peripheral periphery 10c of the growth layer 10. In [Fig.5] (iii), the presence of a hole passing through the growth layer 10 (initial defect) is observed above the barrier 130. During the third step of the process, an active layer 150 of 30 pm is produced by homoepitaxy at a temperature of 1550 °C. At the initial defect, a local inclusion has formed ([Fig.5] (iv)): on either side of this inclusion, an extended defect of the BPD and SSF type appears.The barrier 130 makes it possible to block the extension of the defect towards the center of the active layer 150 (downwards in the figure).

[0059] Of course, the invention also relates to the composite structure 100 comprising the growth layer 10, arranged on the support substrate 20, and the local barrier 130 formed on or in said growth layer 10. It also relates to the composite structure 100 provided with the active layer 150 grown by homoepitaxy on the growth layer 10, and whose local barrier 130 makes it possible to obtain an excellent quality of active layer 150.

[0060] Of course, the invention is not limited to the embodiments and examples described, and variant embodiments may be made without departing from the scope of the invention as defined by the claims.

Claims

Claims

1. Method for manufacturing an active layer (150) of monocrystalline silicon carbide by homoepitaxy on a composite structure (100), the method comprising the following steps: 1) providing a composite structure (100) comprising a growth layer (10) of monocrystalline silicon carbide extending along a main plane (x,y) and arranged on a support substrate (20), the growth layer (10) being delimited by a peripheral periphery (10c) and having a first thickness along an axis normal (z) to the main plane (x,y);2) the formation of a local barrier (130) in or on the growth layer (10), the local barrier extending at a distance and along the peripheral periphery (10c), and corresponding to a physical discontinuity of the growth layer (10) chosen from: - a bump relief induced by the presence of a material on the growth layer (10), said material being different from that of the growth layer, - a hollow relief corresponding to an etched zone of the growth layer (10), or - an amorphous domain or of crystallinity different from the rest of the growth layer (10), the local barrier (130) having a thickness, along the axis (z) normal to the main plane (x,y), less than the first thickness; 3) the epitaxial growth of the active layer (150) on the growth layer (10), the active layer (150) having a second thickness.;

2. A manufacturing method according to claim 1, wherein the first thickness is between 50nm and 1pm.

3. Manufacturing method according to one of claims 1 and 2, in which the peripheral periphery (10c) of the growth layer (10) is located on average between 0.5mm and 2mm from the peripheral edge (20c) of the support substrate (20) of the composite structure (100).

4. Manufacturing method according to one of claims 1 to 3, in which the local barrier (130) is located more than 0.1 mm, more than 0.5 mm, more than 1 mm, more than 2 mm, more than 3 mm, or even more than 5 mm from any point of the peripheral periphery (10c) of the growth layer (10).

5. Manufacturing method according to one of claims 1 to 4, in which the thickness of the local barrier (130) is less than 70%, 50%, 30%, 20%, or even 10% of the first thickness.

6. Manufacturing method according to one of claims 1 to 5, in which the hollow relief is produced by mechanical abrasion, by laser abrasion, by wet etching or by dry etching of the growth layer (10).

7. Manufacturing method according to one of claims 1 to 5, in which the amorphous domain or domain of crystallinity different from the rest of the growth layer (10) is produced by laser amorphization or by ion implantation.

8. Manufacturing method according to one of claims 1 to 5, in which the bump relief is produced by local deposition of a material such as a tungsten nitride or a tungsten disilicide.

9. Manufacturing method according to one of claims 1 to 8, in which the second thickness is greater than or equal to 5 pm, 10 pm, or even 30 pm.

10. Composite structure (100) comprising a growth layer (10) of monocrystalline silicon carbide extending along a main plane (x,y) and arranged on a support substrate (20), the growth layer (10) being delimited by a peripheral periphery (10c) and having a first thickness along an axis normal (z) to the main plane (x,y), the composite structure being characterized in that it comprises a local barrier (130) in or on the growth layer (10), the local barrier extending at a distance and along the peripheral periphery (10c), and corresponding to a physical discontinuity of the growth layer (10) chosen from: - a bump relief induced by the presence of a material on the growth layer (10), said material being different from that of the growth layer, - a hollow relief corresponding to an etched area of the growth layer (10),or - an amorphous domain or one of crystallinity different from the rest of the growth layer (10), the local barrier (130) having a thickness, along the axis (z) normal to the main plane (x,y), less than the first thickness.,

11. A composite structure (100) according to claim 10, wherein the local barrier (130) is located at more than 0.1mm, at more than 0.5mm, at more from 1mm, to more than 2mm, to more than 3mm, or even to more than 5mm from any point of the peripheral edge (10c) of the growth layer (10).

12. Composite structure (100) according to one of claims 10 and 11, in which the thickness of the local barrier (130) is less than 70%, 50%, 30%, 20%, or even 10% of the first thickness.

13. Composite structure (100) according to one of claims 10 to 12, further comprising an active layer (150) of monocrystalline silicon carbide grown by homoepitaxy on the growth layer (10), the active layer (150) having a second thickness.

14. Composite structure (100) according to claim 13, in which the second thickness is greater than or equal to 5 pm, 10 pm, or even 30 pm.

Images