Composite structure including a monocrystalline iii-v compound material layer and associated manufacturing method

Abstract

The invention relates to a composite structure comprising: - a seed layer made of a monocrystalline III-V compound material extending in a main plane, - a support substrate made of crystalline material, on which the seed layer is arranged, via a bonding interface, the support substrate comprising a peripheral perimeter without a seed layer, the peripheral perimeter extending around an edge of the seed layer in the main plane, - an intermediate layer made of amorphous material, arranged between the seed layer and the support substrate and on the peripheral perimeter, - at least one trench in the peripheral perimeter, extending, along an axis normal to the main plane, through the intermediate layer to the support substrate, or even into the support substrate, the trench being at least 100 micrometres from the edge in the main plane. The invention also relates to a method for manufacturing the structure.

Description

Composite structure including a layer of single-crystal III-V composite material and associated manufacturing process FIELD OF INVENTION

[0001] The present invention relates to the field of semiconductor materials for microelectronic components. It relates in particular to a composite structure comprising a support substrate and a seed layer, made of a III-V composite material, assembled via a bonding interface, said seed layer having been transferred from a donor substrate onto said support substrate. Such a structure is generally used to grow at least one epitaxial layer on the seed layer for the purpose of manufacturing components. The invention also relates to a method for manufacturing said composite structure. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] For the fabrication of certain microelectronic or optoelectronic components, particularly HBT and HEMT transistors, lasers, and photodiodes, it is desirable to use composite substrates that provide a thin seed layer of single-crystal III-V composite material on a support substrate of a different composition. This is for economic reasons or to improve certain performance characteristics. For example, consider an InP (indium phosphide) on silicon composite substrate, in which the single-crystal InP layer serves as a seed for the epitaxial growth of a functional stack of III-V layers, traditionally grown on a bulk InP substrate. The silicon substrate provides mechanical strength to the composite substrate and allows for optimization of material costs.

[0003] Composite substrates can be manufactured in various ways, including by bonding a donor substrate to a support substrate and transferring the seed layer (from the donor substrate) to the support substrate via thinning, delamination, or separation steps along a buried brittle plane formed within the donor substrate, as is notably the case in the Smart Cut process. TM The assembled support and donor substrates having chamfers and a certain drop in edges at their periphery, the composite substrate generally presents a peripheral crown at the level of which the seed layer is not transferred.

[0004] The composite substrate is then used to grow one or more epitaxial layer(s) on the seed layer in order to form the functional stack of III-V layers, intended for the manufacture of components.

[0005] Silicon dioxide is a material commonly used as a mask in the epitaxial growth technique known as Selective Area Growth (SAG). In a composite substrate S, the peripheral ring 1c, which lacks a seed layer 4, is generally covered by a layer of silicon dioxide 2, thus preventing the deposition of material in said ring 1c during epitaxial growth.

[0006] It is observed that material not deposited on the oxide layer 2 results in a higher growth rate in the region of the seed layer 4 near the crown 1c. Consequently, the thickness of the epitaxial layer 5 can increase by a factor of three to four at the edge, and the composition of this edge layer can also be altered; these variations in thickness and composition are obviously not favorable to the manufacturing yield of the components. This observation was reported in particular in document WO2018060570.

[0007] An additional problem can arise in the case of epitaxially treated layers that are 5 times thick (typically several micrometers): delamination of the layers is sometimes observed, induced by the stress accumulated in the structure due to the increased thickness and the change in layer composition. Delamination is a major drawback because it can lead to a significant reduction in the effective surface area of ​​functional layers in the composite substrate, and furthermore, it causes contamination of the epitaxial equipment enclosure. SUBJECT OF THE INVENTION

[0008] The present invention proposes a composite structure comprising a support substrate made of a crystalline material on which is disposed a seed layer made of a single-crystal III-V composite material. An intermediate layer made of an amorphous material is interposed between the seed layer and the support substrate, and is present on a peripheral periphery of the support substrate lacking a seed layer. The composite structure includes at least one trench formed in the peripheral periphery and extending through the intermediate layer and down to the support substrate. Such a composite structure makes it possible to reduce the overgrowth of the epitaxial layer at the edge of the seed layer during the growth of the functional stack. The invention also relates to a method for manufacturing the composite structure. BRIEF DESCRIPTION OF THE INVENTION

[0009] The invention relates to a composite structure comprising:

[0010] - a seed layer of monocrystalline III-V compound material extending in a principal plane,

[0011] - a crystalline substrate support on which the seed layer is deposited via a bonding interface, the substrate support comprising a peripheral perimeter devoid of a seed layer, the peripheral perimeter extending around an edge of the seed layer in the principal plane,

[0012] - an intermediate layer of amorphous material, positioned between the seed layer and the supporting substrate and present around the peripheral perimeter,

[0013] - at least one trench present in the peripheral perimeter, extending, along an axis normal to the main plane, through the intermediate layer to the supporting substrate, or even into the supporting substrate, the trench being located less than 100 micrometers from the edge in the main plane.

[0014] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: the trench is located less than 50 micrometers, or even less than 20 micrometers, from the edge of the seed layer; the material composed of the seed layer is selected from indium phosphide, gallium arsenide, gallium nitride, and their ternary or quaternary compounds; the amorphous material of the intermediate layer is selected from silicon dioxide, silicon nitride, a silicon oxynitride, aluminum nitride, alumina; the supporting substrate is formed of a single-crystal or polycrystalline material selected from silicon, sapphire, gallium arsenide, germanium, aluminum nitride, and silicon carbide; the trench has a width, in the principal plane, of between 500 nm and 1 mm, preferably from a few micrometers to 20μm;The trench extends, in the main plane, along the entire edge of the seed layer; the composite structure comprises a plurality of trenches arranged in the peripheral perimeter of the supporting substrate; the area occupied by said trenches in the main plane corresponds to at least 20% of the area of ​​the peripheral perimeter, and preferably between 20% and 80% or 70% or even 60%.

[0015] The invention also relates to a method for manufacturing a composite structure comprising the following steps:

[0016] a) the transfer of a seed layer in a single-crystal III-V composite material, onto a support substrate in a crystalline material, via a bonding interface, an intermediate layer in an amorphous material being interposed between the seed layer and the support substrate and being present on a peripheral periphery of the support substrate devoid of the seed layer, the peripheral periphery extending around a border of the seed layer in a principal plane;

[0017] b) the formation of at least one trench in the peripheral perimeter, the trench extending, along an axis normal to the main plane, through the intermediate layer to the supporting substrate, or even into the supporting substrate, the trench being located less than 100 micrometers from the edge in the main plane.According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: step a) comprises the following substeps: a1) the provision of a donor substrate in monocrystalline III-V compound material and a support substrate in a crystalline material, a2) the formation of a brittle plane buried in the donor substrate, delimiting with a front face of said donor substrate, the seed layer to be transferred, a3) the formation of an intermediate layer, in an amorphous material, on a front face of the support substrate, a4) the bonding by molecular adhesion of the front face of the donor substrate to the intermediate layer of the support substrate, a5) the separation along the buried brittle plane to transfer the seed layer onto the support substrate, on the one hand, and to obtain the remainder of the donor substrate, on the other hand.step b) of forming the -at least one- trench is carried out between substep a3) and substep a4); whereby step b) of forming the -at least one- trench is carried out after substep a5); the manufacturing process includes a step c) of growth by epitaxy of at least one functional layer on the seed layer of the composite structure.

[0018] Finally, according to yet another aspect, the invention relates to a method of using a composite structure comprising the following steps: the provision of a composite substrate as described above; the growth by epitaxy of at least one functional layer on the seed 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] The diagram schematically illustrates the overgrowth of an epitaxial layer (5), in a composite substrate (10) of the prior art, at the edge of the germ layer (4), namely in the vicinity of the peripheral crown devoid of germ layer and comprising a layer of silicon oxide;

[0021]

[0022] Laet and la present a first embodiment of a composite substrate forming part of a composite structure according to the present invention;

[0023]

[0024] Laet and la present a second embodiment of a composite substrate forming part of a composite structure according to the present invention;

[0025]

[0026]

[0027] La, laet laillum illustrate composite structures conforming to the present invention;

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] La, la, la, la', laet la represent a first method of implementing a manufacturing process for a composite structure, in accordance with the present invention;

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] La, la, la, la, laet la' present a second method of implementing a process for manufacturing a composite structure, in accordance with the present invention;

[0040] This presents a step in a manufacturing process according to the invention;

[0041] This presents another step in a manufacturing process according to the invention.

[0042] The same references in the figures can 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 are not necessarily to scale in the figures. DETAILED DESCRIPTION OF THE INVENTION

[0043] The present invention relates to a composite structure 160 comprising in particular a support substrate 10 on which a seed layer 40 is disposed. The support substrate 10 and the seed layer 40 are formed of materials of different natures.

[0044] The substrate support 10 can be chosen in particular for its properties (mechanical, electrical, thermal, etc.), its low cost, and / or its compatibility with microelectronic processes and equipment. It is made of a crystalline material (monocrystalline or polycrystalline), for example, silicon, sapphire, gallium arsenide, germanium, aluminum nitride, and silicon carbide. Its thickness can vary from a few tens to a few hundred micrometers, for example, from 50 μm to 800 μm.

[0045] The seed layer 40 is selected according to the application and the intended components. It serves as a crystal seed for the epitaxy of a single-crystal functional layer 50 in and / or on which the components will be fabricated. The seed layer 40 is made of a single-crystal, type III-V composite material. This composite material can be selected from indium phosphide, gallium arsenide, gallium nitride, and their ternary or quaternary compounds. The thickness of the seed layer 40 typically varies from a few nanometers to a few hundred nanometers, for example, from 10 nm to 1000 nm.

[0046] The seed layer 40 and the support substrate 10 are bonded via a bonding interface 30, which extends along a principal plane (x,y). As will be described later with reference to the manufacturing process according to the invention, the seed layer 40 is assembled and transferred onto the support substrate 10, and not resulting from epitaxial growth or deposition on said substrate 10.

[0047] The assembly including the seed layer 40 and the support substrate 10 is called composite substrate 100 ().

[0048] In the composite substrate 100, the peripheral perimeter 10c of the support substrate 10 is devoid of a seed layer 40. This is a characteristic usually observed on a composite substrate 100 formed by assembly and layer transfer, given the presence of a chamfer and an edge drop at the periphery of the assembled substrates, which prevents the transfer of the seed layer 40 on the peripheral perimeter of the support substrate 10. According to a first embodiment, the composite substrate 100 can consist of a wafer, generally circular (but potentially square or other), having a diameter of 50mm, 100mm, 150mm, 200mm, 300mm, or even more, as is common in the field of microelectronics (,).The peripheral perimeter 10c can have a width (measured radially between the edge of the support substrate 10 and the border 40b of the seed layer 40) of between a few hundred micrometers and a few millimeters, for example, between 200μm and 5mm, more usually between 1mm and 3mm.

[0049] According to a second embodiment, the composite substrate 100 may consist of a portion of a wafer 11, as illustrated in Figures 3a and 3b, or of a chip. The wafer 11 then comprises several adjacent but separated seed layers 40. Each seed layer 40 is disposed on a support substrate 10, a portion of the support 10' of the wafer 11. The peripheral rim 10c in this case is defined as the portion of the support substrate 10 devoid of a seed layer 40, and bordering the seed layer 40. The peripheral rim 10c may have a width ranging from a few hundred micrometers to a few millimeters, for example, from 200 μm to 1 mm.

[0050] The composite substrate 100 further comprises an intermediate layer 20 of an amorphous material, disposed on the support substrate 10 before its assembly onto the seed layer 40, and thus interposed between said substrate 10 and the seed layer 40. The intermediate layer 20 can, in particular, improve the quality and strength of the bonding interface 30. Specifically, it can be composed of silicon dioxide, silicon nitride, or another material. Its thickness can range from a few nanometers to several thousand nanometers, for example, from 50 nm to 2000 nm.

[0051] The intermediate layer 20 is also present on the peripheral perimeter 10c of the support substrate 10.

[0052] Returning to the general description, the composite structure 160 comprises, in addition to the composite substrate 100, at least one trench 60 present in the peripheral perimeter 10c of the support substrate 10. The trench 60 extends, along a z-axis normal to the principal plane (x,y), through the intermediate layer 20 and into the support substrate 10, or even within the support substrate 10. The bottom of the trench 60 thus corresponds to a surface of the crystalline material forming the support substrate 10. The trench 60 has a depth greater than the thickness of the intermediate layer 20 so as to open onto or into the support substrate 10; its depth can reach several micrometers, a few tens of micrometers, or even a few hundred micrometers.

[0053] Trench 60 is also located less than 100 micrometers from the edge 40b of the seed layer 40, in the principal plane (x,y).

[0054] The fact that the trench 60 provides access to a crystalline material (the material of the support substrate 10) at its bottom allows for the nucleation of group III or group V elements contained in the gaseous precursors which will be used during the epitaxy of a functional layer 50 on the seed layer 40. This nucleation can take place at the bottom of the trench 60 (crystalline material forming the support substrate 10) or possibly at the sides of the trench 60 when it penetrates the support substrate 10.

[0055] Since the trench is very close to the edge 40b of the seed layer 40, precursors are "consumed" in this area and are not over-concentrated as in the case where the peripheral perimeter 10c of the support substrate 10 is only covered by the intermediate layer 20 of amorphous material, which blocks any nucleation and growth of material.

[0056] By allowing the incorporation of elements of the gaseous precursors at the level of the peripheral perimeter 10c, the composite structure 160 strongly limits, or even avoids, the overgrowth of the functional layer 50 at the edge of the germ layer 40.

[0057] Advantageously, trench 60 is located less than 50 micrometers, less than 20 micrometers, or even less than 10 micrometers from the edge 40b of the germ layer 40.

[0058] Trench 60 can have a width, in the principal plane (x,y), of between 500nm and a few millimeters, in particular between 5μm and 2mm, or between 20μm and 1mm, or even between 100μm and 500μm.

[0059] According to an advantageous embodiment, the trench 60 extends, in the principal plane (x,y), all along the edge 40b of the seed layer 40. In the example illustrated in figures 4a and 4b, the composite structure 160 is a circular plate and the edge 40b of the seed layer 40 is substantially circular: the trench 60 can then also extend in a circular shape.

[0060] In an alternative case where the composite structure 160 and the border 40b of the seed layer 40 has a square or rectangular shape in the principal plane (x,y), the trench 60 may extend in a similar shape, along the border 40b.

[0061] According to another advantageous embodiment, the composite structure 160 comprises a plurality of trenches 60, which may extend, in the principal plane (x,y), parallel to the boundary 40b of the seed layer 40 or parallel to the tangent to said boundary 40b, perpendicularly, or at any angle to the boundary 40b. In the example shown, the two trenches 60 are concentric in the principal plane (x,y) and, for example, continuously follow the boundary 40b of the seed layer 40. They could optionally be discontinuous in the principal plane (x,y), and appear as dashed lines or as a network of holes, for example. A plurality of trenches 60 extending in radial directions in the principal plane (x,y) could also be envisaged.Let us recall that a trench 60 in the sense of the present invention is not necessarily attached to the notion of "line", each trench 60 can have a point shape (rounded hole or polygon) or elongated shape (continuous or discontinuous), in the principal plane (x,y).

[0062] Preferably, the area occupied by said trenches 60 in the principal plane (x,y) corresponds to at least 20% of the area of ​​the peripheral perimeter 10c, so as to capture sufficient elements of the gaseous precursors at the level of said perimeter 10c and to avoid an overconcentration of precursors at the edge of the seed layer 40. The area occupied by the trenches 60 can be between 20% and typically 80%, 70% or even 60%.

[0063] As an example, the composite structure 160 may include: a support substrate 10 of silicon, circular in shape; an intermediate layer 20 of silicon oxide, 500 nm thick; a seed layer 40 of InP, 300 nm thick and having a circular border 40b; and one, two or three trenches 60, 2000 nm deep, 50 μm wide, spaced 200 μm apart and having a continuous or discontinuous circular shape, concentric to the border 40b; the trench 60 closest to the border 40b of the seed layer 40 being spaced from said border 40b by about 70μm.

[0064] According to another example, the composite structure 160 may include: a support substrate 10 of silicon, circular, square or rectangular in shape, an intermediate layer 20 of silicon oxide, 500 nm thick, a seed layer 40 of GaN, 300 nm thick and having a border 40b of the same shape as the support substrate 10, and 2 trenches 60, 1000 nm deep, 100 μm wide, spaced 100 μm apart and having a circular shape, concentric to the border 40b; the trench 60 closest to the border 40b of the seed layer 40 being spaced from said border 40b by about 40μm.

[0065] The invention also relates to a method for manufacturing the composite structure 160.

[0066] The process includes a step a) corresponding to the transfer of a seed layer (40) of a single-crystal III-V composite material onto a support substrate 10 of a crystalline material, via a bonding interface 30 extending along a principal plane (x,y). The support substrate 10 has a peripheral boundary 10c devoid of the seed layer 40. The peripheral boundary 10c extends around an edge 40b of the seed layer 40 in the principal plane (x,y).

[0067] The seed layer 40 is made of a single-crystal III-V composite material (group III elements: In, Ga, Al, ...; group V elements: As, P, Sb, ...). Its thickness is typically between a few nanometers and 1 micrometer, preferably less than or equal to 1000 nm, 500 nm, 250 nm, or even 100 nm. The single-crystal III-V composite material of the seed layer 40 is advantageously a binary compound, in particular indium phosphide (InP), gallium arsenide (GaAs), or gallium nitride (GaN).

[0068] The support substrate 1 is formed from a single-crystal or polycrystalline material selected from silicon, sapphire, gallium arsenide, germanium, aluminum nitride, and silicon carbide. The support substrate 1 may have a thickness between 50 μm and 800 μm.

[0069] An intermediate layer 20, made of an amorphous material, is positioned between the seed layer 40 and the support substrate 10. This intermediate layer is also present on the peripheral periphery 10c of the support substrate 10, which lacks the seed layer 40. The amorphous material of the intermediate layer 20 is, for example, chosen from silicon dioxide, silicon nitride, silicon oxynitride (SiON), aluminum nitride, and alumina. The thickness of the intermediate layer 20 can range from a few nanometers to several thousand nanometers, for example, from 50 nm to 2000 nm.

[0070] The transfer of step a) can for example lead to an InP type structure (seed layer 40) on Si (support substrate 10), InP on sapphire, InP on GaAs, InP on Ge, InP on SiC, GaAs on Si, GaAs on Sapphire, GaAs on Germanium, GaAs on SiC, GaN on Si, etc., with an intermediate layer 20 in SiO2, SiN, SiON or other amorphous material mentioned above.

[0071] The process further includes a step b) corresponding to the formation of at least one trench 60 in the peripheral perimeter 10c, the trench 60 extending, along an axis z normal to the main plane (x,y), through the intermediate layer 20 and down to the support substrate 10, or even into the support substrate 10. According to the invention, the trench 60 is located less than 100 micrometers from the edge 40b in the main plane (x,y).

[0072] The -at least one- trench 60 can be produced by a mechanical removal or cutting technique (for example, sawing by diamond wheel or laser, to the target trench depth) or an engraving technique (dry or wet) which may in particular involve the classic implementation of masking and optionally photolithography.

[0073] Advantageously, and with reference to the Smart Cut process, step a) of the process comprises the following substeps:

[0074] a1) the supply of a donor substrate 400 in monocrystalline III-V compound material, from which the seed layer 40 will be taken, and the supply of the support substrate 10 in a crystalline material (,);

[0075] a2) the formation of a fragile plane buried 401 in the donor substrate 400, delimiting with a front face of said donor substrate 400, the germ layer 40 to be transferred (,) ;

[0076] a3) the formation of an intermediate layer 20, in an amorphous material, on a front face of the support substrate 10 (,),

[0077] a4) the molecular adhesion bonding of the front face of the donor substrate 400 to the intermediate layer 20 of the support substrate 10, to form a bonded assembly 410 including a bonding interface 30 between the two substrates 400,10 (,) ;

[0078] a5) the separation along the fragile buried plane 401 to transfer the germ layer 40 onto the support substrate 10, on the one hand, and to obtain the remainder of the donor substrate 400', on the other hand (,).

[0079] In substep a1), the donor substrate 400 and support 10 are usually in the form of circular plates, with diameters ranging from 50 mm to 300 mm, depending on material availability. As mentioned previously with reference to the first embodiment of composite substrate 100, the presence of chamfers and edge drops around the periphery of the assembled substrates 400,10 (not shown in Figures 5 and 6) means that the bonding (substep a4) is not effective all the way to the edges and that, consequently, the seed layer 40 is not transferred (substep a5) to the peripheral edge 10c of the support substrate 10 (,). Note that this peripheral perimeter 10c has a width (measured radially between the edge of the support substrate 10 and the edge of the seed layer 40) typically between a few hundred micrometers and a few millimeters, for example, between 200μm and 5mm, more usually between 1mm and 3mm.

[0080] The second embodiment of composite substrate 100 differs from the first in that the transferred seed layer 40 is not unique: during substep a1), several donor substrates 400, for example in the form of vignettes, can be assembled on a support substrate 10', and give rise to the transfer of a plurality of seed layers 40, separated by a peripheral perimeter 10c of the individual support substrate 10, as illustrated in figures 3a and 3b.

[0081] Substep a2) can notably be carried out by ion implantation of light species such as hydrogen and / or helium, as is known from the Smart Cut process. Note that the front face of the donor substrate 400 may include an additional layer, capable of protecting the substrate surface during ion implantation and / or facilitating bonding, improving the quality and strength of the interface, or providing interesting insulation or conductivity properties for the future components to be developed.

[0082] During substep a3), the intermediate layer 20 is formed at least on the front (to be assembled) face of the support substrate 10, typically by thermal oxidation or deposition. The intermediate layer 20 may also be present on the back face of the support substrate 10. This intermediate layer 20 is likely to facilitate bonding, improve the quality and strength of the interface, or provide interesting insulation or conductivity properties for the future components to be developed.

[0083] According to a first variant of the manufacturing process, step b) of forming the -at least one- trench 60 is carried out after substep a3), before substep a4) of gluing (').

[0084] According to a second implementation variant, step b) is operated after substep a5) of separation (').

[0085] Preferably, regardless of the implementation variant, chemical cleaning and / or surface treatments (polishing, plasma, ...) are usually applied to the substrates before substep a4) of assembly.

[0086] As a reminder, direct molecular adhesion bonding (substep a4) does not require an adhesive, as bonds are established at the atomic level between the surfaces being joined. Several types of molecular adhesion bonding exist, differing in particular by their temperature, pressure, atmospheric conditions, and pretreatments required before the surfaces are brought into contact. Examples include room-temperature bonding with or without prior plasma activation of the surfaces to be joined, atomic diffusion bonding (ADB), surface-activated bonding (SAB), and others.

[0087] Substep a5) of separation along the buried fragile plane 401 is usually achieved by applying heat treatment at a temperature between 100°C and 900°C, depending on the materials involved. Such heat treatment induces the development of cavities and microcracks in the buried fragile plane 401, and their pressurization by the light gaseous species present, until a fracture propagates along said fragile plane. Alternatively or concurrently, mechanical stress can be applied to the bonded assembly, and in particular to the buried fragile plane 401, so as to mechanically propagate or assist in propagating the fracture leading to separation.

[0088] The free surface of the germ layer 40 is usually rough after separation.

[0089] A finishing substep (a6) is preferably applied to the composite substrate 100 to restore the crystalline quality and surface condition of the seed layer 40 and to consolidate the bonding interface 30. The finishing may include thermal, mechanical, and / or chemical treatments. It also aims to make the surface of the seed layer 40 compatible with a subsequent growth step by epitaxial growth of the functional layer 50. For this purpose, polishing and cleaning treatments, in particular, may be used.

[0090] In the second variant of the implementation of the process (figures 6a to 6e'), the trench(s) can be made before or after sub-step a6).

[0091] As an example of the realization of a 100 composite substrate (without trenching), one may refer to the publication by B. Ghyselen et al “Large-Diameter III–V on Si Substrates by the Smart Cut Process: The 200 mm InP Film on Si Substrate Example”, physica status solidi (a) Volume 219, Issue 4.

[0092] Alternatively, the thin-film transfer technique can be based on bonding and mechanical and / or chemical thinning. Step a) may then include:

[0093] - the supply of a donor substrate 400 in single-crystal III-V material, having a front face and a back face, and the supply of a support substrate 10,

[0094] - the formation of an intermediate layer 20, in an amorphous material, on a front face of the supporting substrate 10,

[0095] - the molecular adhesion of the front face of the donor substrate 400 onto the support substrate 10, to form a bonded assembly including a bonding interface 30 between the two substrates 400,10,

[0096] - thinning of the back face of the donor substrate 400 to form a seed layer 40 transferred onto the support substrate 10.

[0097] Thinning can be achieved by all known techniques, including grinding (rectification), mechanical or mechano-chemical polishing, and / or chemical etching.

[0098] Step b) of forming the -at least one- trench 60 in the peripheral perimeter 10c can be carried out before gluing or after thinning.

[0099] Returning to the general description, the process may then include a step c) corresponding to the epitaxial growth of a functional layer 50 on the seed layer 40 of the composite structure 160 (). The functional layer 50 is formed of a single-crystal III-V composite material identical to, or epitaxially compatible with, that of the seed layer 40. By epitaxially compatible, we mean having an identical crystalline structure and a lattice parameter sufficiently close to allow proper epitaxial growth according to the knowledge of those skilled in the art. This functional layer 50 may, depending on its composition and the intended components, comprise a stack of several epitaxially grown layers 51, 52.

[0100] Epitaxies of III-V compound materials, particularly those carried out on InP, GaAs, or GaN-based substrates, are usually performed at temperatures between 500°C and 1000°C, for example, by metal-organic chemical vapor deposition (MOCVD). The gaseous precursors used can be, for example, InCl, PH3, or other chlorinated precursors known to those skilled in the art (such as Chlorine Tert-Butyl (TBCl) or (CH3)3CCl), AsH3, Trimethylindium (TMIn), or Triethylgallium (TEGa). The epitaxial layers 51,52 of the functional layer 50 can be formed of binary, ternary, quaternary III-V compounds, or even comprising more than four elements, arranged according to a functional stacking for the development of microelectronic components such as HBT and HEMT transistors, lasers or photodiodes.

[0101] In step c), during the heating of the composite structure 160 in the epitaxial chamber, the bottom (made of crystalline material) and possibly the sides of each trench 60 will react with the gaseous precursors in the atmosphere within the epitaxial chamber and capture elements (from the gaseous precursors) destined to form the III-V composite material of the functional layer 50, thus forming a polycrystalline material inside the trench 60: a filled trench 61 therefore appears. The continuation of polycrystalline growth at the peripheral edge 10c induces the formation of a polycrystalline layer 65 ((i) and (ii)).A polycrystalline layer 65 comprising a composite material, based on the elements composing the composite material III-V of the first epitaxial layer 51 (then of the second, and so on), is thus formed on the support substrate 10, at the level of the peripheral perimeter 10c, in parallel with the epitaxial growth of the functional layer 50.

[0102] By allowing the incorporation of elements of the gaseous precursors at the level of the peripheral periphery 10c, the composite structure 160 strongly limits, or even avoids, the overgrowth of the functional layer 50 at the edge of the germ layer 40. It thus promotes a uniform and good quality epitaxial growth of the different epitaxial layers 51,52 of the functional layer 50 on the germ layer 40.

[0103] The manufacturing process may finally include a step d) of removing the polycrystalline layer 65, in particular by mechanical grinding or by wet or dry chemical etching of the peripheral rim 10c ((i)). An advantage of the fact that the trenches 60 can be arranged in the peripheral rim 10c with relative freedom is that the location of the polycrystalline layer 65 can be chosen, and said polycrystalline layer 65 potentially more easily removed.

[0104] Optionally, the polycrystalline material contained in the -at least one- filled trench 61 can also be removed, to find one (or more) empty trenches 60.

[0105] The resulting structure can then follow the classic steps required for the development of components in and / or on the functional layer 50.

[0106] 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

Composite structure (160) comprising: - a seed layer (40) of monocrystalline III-V composite material extending in a principal plane (x,y), - a support substrate (10) of crystalline material, on which the seed layer (40) is disposed, via a bonding interface (30), the support substrate (10) comprising a peripheral boundary (10c) devoid of seed layer (40), the peripheral boundary (10c) extending around an edge (40b) of the seed layer (40) in the principal plane (x,y), - an intermediate layer (20) of amorphous material, disposed between the seed layer (40) and the support substrate (10) and present on the peripheral boundary (10c), - at least one trench (60) present in the peripheral boundary (10c), extending, along an axis (z) normal to the principal plane (x,y), through the intermediate layer (20) up to the supporting substrate (10), or even within the supporting substrate (10),the trench (60) being located less than 100 micrometers from the edge (40b) in the principal plane (x,y). Composite structure (160) according to the preceding claim, in which the trench (60) is located less than 50 micrometers, or even less than 20 micrometers, from the edge (40b) of the seed layer (40). Composite structure (160) according to any one of the preceding claims, wherein the material composed of the seed layer (40) is selected from indium phosphide, gallium arsenide, gallium nitride, and their ternary or quaternary compounds. Composite structure (160) according to any one of the preceding claims, wherein the amorphous material of the intermediate layer (20) is selected from silicon oxide, silicon nitride, silicon oxynitride, aluminium nitride, alumina. Composite structure (160) according to any one of the preceding claims, wherein the support substrate (10) is formed of a single-crystal or polycrystalline material selected from silicon, sapphire, gallium arsenide, germanium, aluminum nitride and silicon carbide. Composite structure (160) according to any one of the preceding claims, wherein the trench (60) has a width, in the principal plane (x,y), of between 500nm and 1mm, preferably from a few micrometers to 20μm. Composite structure (160) according to any one of the preceding claims, wherein the trench (60) extends, in the principal plane (x,y), all along the edge (40b) of the seed layer (40). Composite structure (160) according to any one of the preceding claims, comprising a plurality of trenches (60) arranged in the peripheral perimeter (10c) of the support substrate 10. Composite structure (160) according to the preceding claim, wherein the area occupied by said trenches (60) in the principal plane (x,y) corresponds to at least 20% of the area of ​​the peripheral perimeter (10c), and preferably between 20% and 80% or 70% or even 60%. A method for manufacturing a composite structure (160) comprising the following steps: a) transferring a seed layer (40) of a single-crystal III-V composite material onto a support substrate (10) of a crystalline material, via a bonding interface (30), an intermediate layer (20) of an amorphous material being interposed between the seed layer (40) and the support substrate (10) and being present on a peripheral periphery (10c) of the support substrate (10) devoid of the seed layer (40), the peripheral periphery (10c) extending around an edge (40b) of the seed layer (40) in a principal plane (x,y); b) forming at least one trench (60) in the peripheral periphery (10c), the trench (60) extending, along an axis (z) normal to the principal plane (x,y), through the intermediate layer (20) to the support substrate (10), even in the supporting substrate (10), the trench (60) being located less than 100 micrometers from the edge (40b) in the principal plane (x,y). A manufacturing process according to the preceding claim, wherein step a) comprises the following substeps: a1) the provision of a donor substrate (400) of single-crystal III-V composite material and a support substrate (10) of a crystalline material, a2) the formation of a buried brittle plane (401) in the donor substrate (400), delimiting with a front face of said donor substrate, the seed layer (40) to be transferred, a3) the formation of an intermediate layer (20), of an amorphous material, on a front face of the support substrate (10), a4) the bonding by molecular adhesion of the front face of the donor substrate (400) to the intermediate layer (20) of the support substrate (10), a5) the separation along the buried brittle plane (401) to transfer the seed layer (40) onto the support substrate (10), on the one hand, and to obtain the remainder (400') of the donor substrate, on the other hand. A manufacturing method according to the preceding claim, wherein step b) of forming the -at least one- trench (60) is carried out between substep a3) and substep a4). A manufacturing method according to claim 11, wherein step b) of forming the -at least one- trench (60) is carried out after substep a5). Manufacturing method according to one of the two preceding claims, comprising a step c) of growth by epitaxy of at least one functional layer (50) on the seed layer (40) of the composite structure (160). Method of using a composite structure (160) comprising the following steps: supplying a composite substrate (100) according to one of claims 1 to 9; growing by epitaxy at least one functional layer (50) on the seed layer (40) of the composite structure (160).

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