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

Abstract

The invention relates to a composite structure, comprising: - a carrier substrate made of monocrystalline silicon having a front face and a rear face, - an interlayer made of a crystalline material chosen from III-V compound materials excluding III-N compound materials, germanium and silicon-germanium, said interlayer being arranged directly on the carrier substrate on its front face, - a seed layer made of a monocrystalline material having a first lattice parameter, said seed layer being intended to serve as a seed crystal for the epitaxy of a functional layer (50) made of a monocrystalline III-V compound material, and being arranged on the front face of the carrier substrate, a peripheral edge of the carrier substrate having no seed layer, - an intermediate layer made of an amorphous or polycrystalline material, arranged between the interlayer and the seed layer, and absent from the peripheral edge of the carrier substrate, said intermediate layer being adjacent to a bonding interface. The invention also relates to a method for manufacturing said composite 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 single-crystal material, assembled via a bonding interface and transferred from a donor substrate onto said support substrate. A functional layer is intended to be formed by epitaxial growth on the seed layer, for the purpose of manufacturing components, and also to be formed on an intercalated layer present on a peripheral periphery of the support substrate. The invention also relates to a method for manufacturing said composite structure.

[0002] TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] 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 material, such as a single-crystal III-V compound, deposited on a support substrate of a different material than the seed layer. 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. US patent 2018 / 269105 describes a "III-V-and-Si" substrate and its fabrication process.

[0004] 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) onto the support substrate via thinning, delamination, or separation steps along a buried weak 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 perimeter at the level of which the seed layer is not transferred.

[0005] 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.

[0006] 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 boundary 1c, which lacks a seed layer 4, is generally covered by a layer of silicon dioxide 2, thus preventing nucleation of the material in said peripheral boundary 1c during epitaxial growth, notably by MOCVD (Metal-Organic Chemical Vapor Deposition).

[0007] 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 peripheral boundary 1c. Consequently, the thickness of the epitaxial layer 5 can increase by a factor of three to four at the edge of the seed layer 4 (over a region typically less than or equal to 1 mm), and the composition of this edge layer can also be modified; these variations in thickness and composition are obviously not favorable to the manufacturing yield of the components.

[0008] Another problem can arise with epitaxial 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 composition of the edge layers. Delamination is a major drawback because it can lead to a significant reduction in the effective surface area of ​​functional layers, as well as defects in subsequent component manufacturing steps. Furthermore, it causes contamination of the epitaxial growth matrix.

[0009] SUBJECT OF THE INVENTION

[0010] The present invention proposes a composite structure addressing the aforementioned problems. The composite structure comprises a support substrate on which a seed layer of a single-crystal material derived from a donor substrate is deposited. The peripheral perimeter of the support substrate, which lacks a seed layer, is provided with an interlayer, allowing the growth of a functional layer on said interlayer (in parallel with the growth of a functional layer on the seed layer), thus preventing any overgrowth at the edge of the seed layer. The invention also relates to a method for manufacturing the composite structure.

[0011] BRIEF DESCRIPTION OF THE INVENTION

[0012] The invention relates to a composite structure comprising:

[0013] - a monocrystalline silicon support substrate having a front face and a rear face,

[0014] - an interlayer of a crystalline material selected from III-V compound materials excluding III-N compound materials, germanium and silicon-germanium, said interlayer being disposed directly on the substrate support on its front face,

[0015] - a seed layer made of a single-crystal material having a first lattice parameter, said seed layer being disposed on the front face of the supporting substrate, a peripheral perimeter of the supporting substrate being devoid of a seed layer,

[0016] - an intermediate layer of an amorphous or polycrystalline material, disposed between the intercalated layer and the seed layer, and absent from the peripheral perimeter of the support substrate, said intermediate layer being adjacent to a bonding interface.

[0017] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: The composite structure further comprises a functional layer of a single-crystal III-V compound material having a second lattice parameter identical to the first lattice parameter or differing from it by less than 2%, an epitaxial interface extending between the functional layer and the seed layer, and between the functional layer and the intercalated layer; the second lattice parameter differs from the first lattice parameter by less than 1%, or even by less than 0.5%; the seed layer material is a III-V compound material selected from indium phosphide, gallium arsenide, and their ternary or quaternary compounds, or the seed layer material is germanium; the intercalated layer is silicon oxide;the intercalated layer has a thickness greater than or equal to 50nm, preferably between 100nm and 1000nm.;

[0018] The invention also relates to a method for manufacturing a composite structure comprising the following steps:

[0019] a) the supply of a monocrystalline silicon support substrate having a front face and a rear face,

[0020] b) the formation of an interlayer of a crystalline material selected from III-V compound materials excluding III-N compound materials, germanium and silicon-germanium, said interlayer being disposed directly on the substrate support on its front face side,

[0021] (c) the provision of a donor substrate made of a single-crystal material having a first lattice parameter, a front face and a back face; an intermediate layer made of an amorphous or polycrystalline material being disposed on the donor substrate, at least on the side of its front face,

[0022] d) Assembly of the support and donor substrates by their respective front faces, via a bonding interface,

[0023] e) the transfer of a layer from the donor substrate, called the seed layer, to obtain a composite structure comprising the support substrate, the intercalated layer, the intermediate layer and the seed layer, a peripheral perimeter of the support substrate being devoid of seed layer and intermediate layer.

[0024] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: the manufacturing process further comprises: (f) the formation, by epitaxy, of a functional layer in a single-crystal III-V composite material having a second lattice parameter identical to the first lattice parameter or differing from the latter by less than 2%, on the intercalated layer at the level of the peripheral perimeter and on the seed layer; the intercalated layer formed in step (b) has a thickness greater than or equal to 50nm, preferably between 100nm and 1000nm;The process comprises: a step b'), after step b), comprising the formation of a bonding layer on the interlayer, said bonding layer being of an amorphous or polycrystalline material, in particular silicon oxide, and a step e', after step e) and before step f), of removing the bonding layer at the periphery; the process comprises a step g) of removing all or part of the functional layer and the interlayer at the periphery, by mechanical grinding or by chemical etching. BRIEF DESCRIPTION OF THE FIGURES

[0025] 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:

[0026] The diagram schematically illustrates the overgrowth of an epitaxial layer, in a state-of-the-art composite substrate, at the edge of the germ layer, namely near the peripheral perimeter which is devoid of a germ layer and includes a layer of silicon oxide;

[0027]

[0028]

[0029]

[0030] La, la, laet la present four examples of composite structure according to the present invention;

[0031]

[0032] Laet and la present a first embodiment of a composite structure conforming to the present invention;

[0033]

[0034] Laet and la present a second embodiment of a composite structure according to the present invention;

[0035]

[0036]

[0037]

[0038]

[0039] La, la, la, la and la represent manufacturing steps of a composite structure conforming to the present invention;

[0040]

[0041]

[0042]

[0043] La, la, laet la represent steps in a manufacturing process for a composite structure according to the present invention.

[0044] The same references in the figures can be used for elements of the same type. The figures are schematic representations which, for the sake of clarity, are not to scale. In particular, the thicknesses of the layers 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

[0045] The present invention relates to a composite structure 150 comprising a support substrate 10 on which several layers (,,,) are stacked.

[0046] The monocrystalline silicon substrate 10 is chosen in particular for its mechanical properties, low cost, and compatibility with microelectronic processes and equipment. Its thickness can vary from a few tens to several hundred micrometers, for example, between 300 μm and 1000 μm. It has a front face 10a and a back face 10b, these two faces 10a, 10b extending parallel to a principal plane (x,y) in the figures.

[0047] The support substrate 10 is provided, at least on the side of its front face 10a, with an intercalated layer 15 of a crystalline material chosen from: III-V compound materials (for example InP, GaAs, and their ternary and quaternary compounds), excluding III-N compound materials, germanium, silicon-germanium.

[0048] The interlayer 15 is in direct contact with the support substrate 10. Preferably, an epitaxial interface connects the interlayer 15 and the support substrate 10. The material of the interlayer 15 is single-crystal or polycrystalline. Its crystalline quality is not critical, but this layer 15 must have a roughness compatible with a bonding step, typically <0.5 nm RMS (AFM measurement on a 1x1µm² scan), at least when it is intended to be directly bonded.

[0049] Preferably, the intercalated layer 15 has a thickness greater than or equal to 50nm, typically between 100nm and 1000nm.

[0050] The composite structure 150 also includes a seed layer 40 disposed on the front face 10a of the support substrate 10. The nature of the seed layer 40 is chosen according to the application and the intended components. It is designed to serve 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 material with a first lattice parameter. This material can be a III-V compound, notably chosen from indium phosphide, gallium arsenide, and their ternary or quaternary compounds. The seed layer 40 can also be made of germanium. Its thickness typically varies from a few nanometers to a few hundred nanometers, for example, from 10 nm to 1000 nm.

[0051] In the composite structure 150, an intermediate layer 20 is further arranged between the intercalated layer 15 and the seed layer 40. It is composed of an amorphous or polycrystalline material, and can have a thickness ranging from a few nanometers to a few micrometers, for example between 100nm and 1000nm. A commonly used intermediate layer 20 is a silicon oxide, formed by deposition or native (i.e., formed spontaneously on the surface of the substrate, exposed to oxygen or atmospheric humidity), but other types of amorphous or polycrystalline materials can of course be considered (SiN, amorphous Si, amorphous SiC, metallic layers, etc.).

[0052] The intermediate layer 20 is adjacent to a bonding interface 25. As will be described later with reference to the manufacturing process according to the invention, the intermediate layer 20 is assembled on the front face 10a of the support substrate 10 and transferred, together with the seed layer 40, onto said substrate; the seed layer 40 is not derived from epitaxial growth or deposition on the support substrate 10.

[0053] In the examples illustrated in Figures 2a and 2c, the bonding interface 25 is located between the intermediate layer 20 and the intercalated layer 15.

[0054] In the composite structure 150, the peripheral perimeter 10c of the support substrate 10 is devoid of a seed layer 40 and an intermediate layer 20. This is a characteristic usually observed on a composite structure 150 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 layers on the peripheral perimeter of the support substrate 10. The peripheral perimeter 10c is covered by the intercalated layer 15.

[0055] According to a first embodiment, the composite structure 150 can consist of a wafer, generally circular (but potentially square or otherwise), with a diameter of 50 mm, 100 mm, 150 mm, 200 mm, 300 mm, 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 edge of the seed layer 40) ranging from a few hundred micrometers to a few millimeters, for example, between 200 μm and 5 mm, more commonly between 1 mm and 3 mm.

[0056] According to a second embodiment, the composite structure 150 can consist of a portion of a wafer 11, as illustrated in Figures 4a and 4b, or of a chip. The wafer 11 then comprises several adjacent stacks [seed layer 40 – intermediate layer 20], separated from each other in the principal (x,y) plane. The support substrate 10 is then a portion of the support 10' of the wafer 11. The peripheral rim 10c in this case is defined as the part of the support substrate 10 lacking a seed layer 40 and an intermediate layer 20, and bordering said seed layer 40. The peripheral rim 10c can have a width ranging from a few hundred micrometers to a few millimeters, for example, from 200 μm to 1 mm or even up to 5 mm.

[0057] The composite structure 150 may optionally include a bonding layer 30 on the front face 10a of the supporting substrate 10, in which case the bonding interface 25 is located between the bonding layer 30 and the intermediate layer 20. The bonding layer 30 can, in particular, improve the quality and strength of the bonding interface 25. Specifically, it can be composed of silicon oxide, silicon nitride, or other materials. The presence of the bonding layer 30 can reduce the surface roughness requirements of the intermediate layer 15.

[0058] The composite structure 150 may further include a functional layer 50 made of at least one single-crystal III-V composite material, having a second lattice parameter identical to the first lattice parameter or differing from it by less than 2%. In other words, the functional layer 50 is formed from at least one material whose crystalline structure is identical to the single-crystal material constituting the seed layer 40, and whose lattice parameter is matched to within + / -2% of the first lattice parameter. Advantageously, the second lattice parameter differs by less than 1%, or even less than 0.5%, from the first lattice parameter.

[0059] An epitaxial interface extends between the functional layer 50 and the seed layer 40, and between the functional layer 50 and the intercalated layer 15. Since the seed layer 40 is of excellent crystalline quality, the functional layer 50 formed on the seed layer 40, in the so-called useful region 151 of the composite structure 150, is also expected to be of excellent quality.

[0060] In a region directly above the peripheral perimeter 10c, called the crown 152 of the composite structure 150, the functional layer 50 is raw on the interlayer layer 15. It is therefore important to note that, in the case where a bonding layer 30 has been added on the interlayer layer 15 to assemble and transfer the seed layer 40 and the intermediate layer 20, said bonding layer 30 must be removed before the formation of the functional layer 50.

[0061] The intercalated layer 15 may exhibit a lower crystallographic quality (compared in particular to the seed layer 40) and the material of which it is composed is not necessarily adjusted to the second lattice parameter; thus, the portion of functional layer 50 found in the crown 152 of the composite structure 150 is not expected with a high crystalline quality.

[0062] In a particular example, the composite structure 150 may comprise, from bottom to top in the figures: a monocrystalline silicon support substrate 10, an interlayer 15 of InP or Ge 100 nm thick, directly epitaxially bonded to the silicon, an intermediate layer 20 of silicon oxide 500 nm thick, not present on the peripheral edge 10c of the support substrate 10, the bonding interface 25 being located between the interlayer 15 and the intermediate layer 20, a seed layer 40 of InP 500 nm thick, not present on the peripheral edge 10c of the support substrate 10, a functional layer 50 comprising a stack of different InP layers and ternary or quaternary compounds, depending on the type of components intended, epitaxially bonded to the seed layer 40. For example, the stack is of the InP / In type 0,53 Ga 0,47 As / InP / In 0,53 Ga 0,47As with a view to developing, on the composite structure 150, a photodiode in the short IR wavelengths (SWIR for "short wavelength infrared" according to Anglo-Saxon terminology) of PIN structure.

[0063] The presence of the intercalated layer 15, on the peripheral perimeter 10c of the support substrate 10 allows the growth of a functional layer 50 in the region directly above the peripheral perimeter 10c (crown 152); the gaseous precursors used during the epitaxial growth of the functional layer 50 are therefore captured at the level of the crown 152, which avoids the overgrowth of the functional layer 50 of single-crystal structure, at the level of an outer border of the useful region 151, in other words, directly above a border of the seed layer 40.

[0064] The invention also relates to a method for manufacturing the composite structure 150.

[0065] The process includes a step a) corresponding to the provision of a monocrystalline silicon support substrate 10 having a front face 10a and a back face 10b, extending parallel to a plane (x,y). The crystal orientation of the silicon is preferably (001). Its thickness can vary, for example, between 300μm and 1000μm.

[0066] The next step (b) involves the formation of an interlayer 15 on the support substrate 10. This interlayer 15 is made of a crystalline material selected from III-V composite materials, excluding III-N composite materials, germanium, and silicon-germanium. The nature of this interlayer 15 must allow the epitaxial growth of the future functional layer 50 at the peripheral edge 10c of the support substrate 10, a region free of a seed layer 40. The functional layer 50 is intended to be made of III-V composite materials, typically based on InP or GaAs (and associated ternary and quaternary compounds); thus, III-V composite materials of the same type can be suitable for the interlayer 15.Germanium or SiGe (preferably with a high proportion of germanium, typically >70% or even >80%, especially for a functional layer in GaAs), with a crystalline structure compatible with the aforementioned III-V compound materials, may also be suitable.

[0067] Since the interlayer layer 15 is disposed directly on the support substrate 10 on the side of its front face 10a, it must also be able to grow relatively uniformly on the silicon.

[0068] Step b) can be performed by any known epitaxial technique, including molecular beam epitaxy (MBE) or metal-organic vapor deposition (MOCVD). The presence of a native oxide on the surface of the substrate 10 can disrupt or even prevent the deposition of a uniform, crystalline interlayer 15. Given the high stability of the native oxide on silicon, it is preferable to remove it by chemical etching (wet or dry) just before performing step b).

[0069] The interlayer 15 formed in step b) advantageously has a thickness greater than or equal to 50 nm, so that a non-zero thickness of the interlayer 15 always remains on the support substrate 10 (in particular at the peripheral edge 10c) before step f) of the process. Indeed, cleaning, polishing, or etching operations that may be carried out during the process steps (before step f)) are likely to etch at least partially the interlayer 15 at the peripheral edge 10c. Preferably, the thickness of the interlayer 15 is between 100 nm and 1000 nm.

[0070] The manufacturing process includes a step c) corresponding to the supply of a donor substrate 400 in a single-crystal material having a first lattice parameter, a front face 400a and a back face 400b ((i)). The single-crystal material may be a III-V compound material, in particular selected from indium phosphide, gallium arsenide, and their ternary or quaternary compounds. Alternatively, it may be germanium.

[0071] An intermediate layer 20, made of an amorphous or polycrystalline material, is deposited on the donor substrate 400, at least on its front face 400a. For example, the intermediate layer 20 may consist of a native oxide or one deposited on the donor substrate 400. The intermediate layer 20 is typically between a few nanometers and a few micrometers thick, for example, between 100 nm and 1000 nm. A commonly used intermediate layer 20 is silicon oxide, but other types of amorphous or polycrystalline materials can of course be considered.

[0072] In the next step d) of the process, the assembly of the support substrate 10 and donor 400, by their respective front faces 10a,400a, is carried out, forming a bonded assembly 410 provided with a bonding interface 25 ().

[0073] Preferably, the assembly is based on direct molecular adhesion, which does not require an adhesive material, as bonds are established at the atomic scale between the surfaces being joined. Several types of molecular adhesion 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.

[0074] Cleaning and surface treatments (polishing, plasma, etc.) are usually applied to the substrates before assembly.

[0075] The bonding interface 25 can connect the intermediate layer 20 and the intercalated layer 15.

[0076] Alternatively, a 30-layer adhesive can be added to the interlayer 15 (on the front face 10a of the support substrate 10) to promote (or simplify) assembly with the intermediate layer 20.

[0077] The manufacturing process then includes a step b'), following step b), comprising the formation of a bonding layer 30 on the interlayer layer 15, said bonding layer 30 being made of an amorphous or polycrystalline material. For example, the bonding layer 30 can be silicon dioxide, which is well known and understood in the context of direct bonding.

[0078] 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 the composite structure 150 (,), the presence of chamfers and edge drops around the periphery of the assembled substrates 400,10 (not shown in the figures) means that the assembly is not effective all the way to the edges and that, consequently, the seed layer 40 (from the donor substrate 400) will not be transferred to a peripheral edge 10c of the support substrate 10 during the next step e) of the process. 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.

[0079] The second embodiment of the composite structure 150 (stated previously, see figures 4a and 4b) differs from the first in that the transferred seed layer 40 is not unique: several donor substrates 400, for example in the form of vignettes, can be assembled on the support substrate 10 (portion of a support 10'), and give rise to the transfer of a plurality of seed layers 40, separated by a peripheral perimeter 10c devoid of seed layer 40 and intermediate layer 20, but provided with the intercalary layer 15.

[0080] The manufacturing process then includes a step e) of transferring a layer from the donor substrate 400, called the seed layer 40, to obtain a composite structure 150 comprising the support substrate 10, the interlayer layer 15, the intermediate layer 20 and the seed layer 40 (). The peripheral perimeter 10c of the support substrate 10 is devoid of the seed layer 40 and the intermediate layer 20 (not shown in the figure).

[0081] The composite structure 10 is developed by a thin film transfer technique, involving an assembly between the intermediate layer 20 (on the front face of the donor substrate 400) and the intercalated layer 15 (on the front face 10a of the support substrate 10), via the bonding interface 25.

[0082] According to an advantageous embodiment, and with reference to the Smart Cut process, step c) comprises the formation of a buried brittle plane 401 within the donor substrate 400, delimiting, with a front face 400a of said donor substrate 400, the seed layer 40 to be transferred ((ii)). As is well known, the buried brittle plane 401 consists of a layer embedded within the donor substrate 400 that contains crystalline defects and light species capable of evolving into microcavities and microcracks extending predominantly parallel to the main plane (x,y). The buried brittle plane 401 can notably be obtained by ion implantation of light species such as hydrogen and / or helium, as is well known.

[0083] The intermediate layer 20 is formed on the donor substrate 400 before or after the formation of the buried brittle plane 401. If the deposition is carried out after the buried brittle plane 401 is formed, it must be carried out at a sufficiently low temperature so as not to negatively affect the buried brittle plane 401.

[0084] According to the advantageous implementation method, step e) comprises a separation along the buried fragile plane 401, to transfer the seed layer 40 and the intermediate layer 20 onto the support substrate 10 and obtain the composite structure 150, on the one hand, and the remainder of the donor substrate 400', on the other hand ((ii)). The separation along the buried fragile plane 401 is usually achieved by applying a heat treatment at a temperature between 100°C and 900°C, depending on the materials involved. Such a heat treatment induces the development of cavities and microcracks in the buried fragile plane 401, and their pressurization by the light species present in gaseous form, until a fracture propagates along said fragile plane.Alternatively or jointly, mechanical stress may be applied to the bonded assembly and in particular to the level of the buried weak plane 401, so as to propagate or help to propagate mechanically the fracture leading to separation.

[0085] The free surface of the seed layer 40 is usually rough after separation. A finish is preferably applied to the composite structure 150 to restore the crystalline quality and surface condition of the seed layer 40 and to consolidate the bonding interface 25. The finish 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 stage by epitaxial growth of the functional layer 50. For this purpose, polishing and cleaning treatments, in particular, may be used.

[0086] As an example of implementation, one can 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.

[0087] Alternatively, the thin film transfer technique can be based on mechanical and / or chemical thinning of the back face 400b of the donor substrate 400, including grinding (rectification), mechanical or mechano-chemical polishing, and / or chemical etching ((i),(i)).

[0088] If a bonding layer 30 is present on the interlayer 15, at the level of the peripheral perimeter 10c of the support substrate 10, in the composite structure 150 obtained after step e) ( ), the manufacturing process may include, prior to a subsequent step f) of growth of the functional layer 50, a step e') of removal of the bonding layer 30 at the level of the peripheral perimeter 10c, so as to expose the interlayer 15.

[0089] Such removal can be achieved by chemical etching, wet or dry.

[0090] The process advantageously includes a step f) corresponding to the formation, by epitaxy, of a functional layer 50 on the intercalated layer 15 at the peripheral boundary 10c and on the seed layer 40 (,). The functional layer 50 is made of a single-crystal III-V composite material having a second lattice parameter identical to the first lattice parameter or differing from it by less than 2%.

[0091] Any known technique can be used. MOCVD deposition is particularly well-suited to III-V composite materials and offers attractive growth rates. MOCVD relies on the thermal decomposition of gaseous precursors containing the elements necessary for the formation of the desired material. As mentioned in the introduction, if the gaseous precursors do not react with the layer located at the peripheral edge 10c, an overgrowth of the functional layer 50 occurs at the edge of the seed layer 40. In the present invention, the presence of the intercalated layer 15 on the support substrate 10, at the peripheral edge 10c, allows for a reaction of the gaseous precursors and growth of the functional layer 50 in the useful region 151, but also in the ring 152 of the composite structure 150.Thus, the problem of overgrowth directly above the edge of the germ layer 40 and all associated disadvantages are eliminated.

[0092] MOCVD epitaxy of III-V compound materials is typically carried out between 600°C and 800°C. It is common to apply a pre-bake in the epitaxy reactor under an H2 atmosphere (or other reducing gases) to reduce and desorb the native oxide on the surface of the seed layer 40.

[0093] The nature of the material of the intercalated layer 15 is chosen so that the native oxide which forms on its surface is unstable and can be easily removed during a pre-annealing conventionally carried out prior to the epitaxy of III-V compound materials.

[0094] Thus, the III-V compound material of the functional layer 50 is of single-crystal structure and high quality in the useful region 151 (region directly above the seed layer 40), said material having a lattice parameter (second lattice parameter) identical to the first lattice parameter (of the seed layer 40) or differing from it by less than 2%, or even less than 1%, or even less than 0.5%. In the corona 152 (region directly above the peripheral rim 10c), the III-V compound material of the functional layer 50 is also deposited, due to the presence of the intercalated layer 15 as a growth initiator. Its crystalline structure being of high quality is not important.

[0095] The manufacturing process may finally include a step g) of removing all or part of the functional layer 50 and optionally of the intercalated layer 15 at the level of the peripheral perimeter 10c (i.e. in the crown 152 of the composite structure 150), by mechanical lapping or by chemical etching (,,,).

[0096] Such a step generally involves prior protection of the part of the functional layer 50 in the useful region 151, followed by the removal.

[0097] The composite structure 150 (with or without removal of layers 50,15 in the crown 152) can then follow the classic steps required for the development of components in and / or on the functional layer 50 of the useful region 151.

[0098] Example of a completed project:

[0099] A donor substrate 400 in monocrystalline InP of 150mm diameter on the front face 400a of which a silicon oxide of 500nm thickness is deposited is implanted, on the side of its front face 400a, with hydrogen ions, generating a buried fragile plane 401.

[0100] A 150mm diameter monocrystalline silicon substrate 10 is subjected to HF chemical etching, followed by InP deposition via MOCVD (epitaxial conditions, for example, such as those proposed by Grundmann et al. in "Antiphase-domain-free InP on Si(001): optimization of MOCVD process" (Materials Science, Engineering, Physics, Journal of Crystal Growth, December 1991). An interlayer 15 of crystalline InP, 150nm thick, is thus formed.

[0101] A cleaning is applied to both substrates 400, 10 prior to molecular adhesion bonding between the respective front faces of the substrates 400,10 at room temperature, to form a bonded assembly 410.

[0102] A heat treatment to consolidate the bond interface is applied to the bonded assembly 410. Then, fracture annealing causes separation along the buried brittle plane 401, resulting in a composite substrate 100 (InP / SiO2 / InP / Si) on one side, and the remainder of the donor substrate 400' on the other. The InP seed layer 40 has a lattice parameter of 5.8 Å.

[0103] A mechano-chemical polishing smoothing treatment is applied to the free surface of the germ layer 40 in InP, followed by conventional cleaning to provide a germ layer 40 surface favorable to epitaxy.

[0104] A functional layer 50 based on InP is formed by MOCVD on the seed layer 40. It has a thickness of 4500 nm.

[0105] The composite structure 150 thus obtained can be used for the manufacture of components or for a new epitaxial growth of a particular stack.

[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 (150) comprising: - a support substrate (10) of single-crystal silicon having a front face (10a) and a back face (10b), - an interlayer (15) of a crystalline material selected from III-V composite materials excluding III-N composite materials, germanium, and silicon-germanium, said interlayer (15) being disposed directly on the support substrate (10) on the side of its front face (10a), - a seed layer (40) of a single-crystal material having a first lattice parameter, said seed layer being intended to serve as a crystal seed for the epitaxy of a functional layer (50) of a single-crystal III-V composite material, and being disposed on the front face (10a) of the support substrate (10), a peripheral periphery (10c) of the support substrate (10) being devoid of a seed layer (40), - an intermediate layer (20) of an amorphous material or polycrystalline,arranged between the intercalated layer (15) and the germinal layer (40), and absent from the peripheral perimeter (10c) of the supporting substrate (10), said intercalated layer (20) being adjacent to a bonding interface (25). Composite structure (150) according to claim 1, further comprising a functional layer (50) of a single-crystal III-V composite material having a second lattice parameter identical to the first lattice parameter or differing from the latter by less than 2%, an epitaxial interface extending between the functional layer (50) and the seed layer (40), and between the functional layer (50) and the intercalated layer (15). Composite structure (150) according to the preceding claim, wherein the second mesh parameter differs from the first mesh parameter by less than 1%, or even by less than 0.5%. Composite structure (150) according to any one of the preceding claims, wherein: - the seed layer material (40) is a III-V compound material selected from indium phosphide, gallium arsenide, and their ternary or quaternary compounds, or - the seed layer material (40) is germanium. Composite structure (150) according to any one of the preceding claims, wherein the intermediate layer (20) is made of silicon oxide. Composite structure (150) according to any one of the preceding claims, wherein the interlayer layer (15) has a thickness greater than or equal to 50nm, preferably between 100nm and 1000nm. Method of manufacturing a composite structure (150) comprising the following steps: a) supplying a support substrate (10) of single-crystal silicon having a front face (10a) and a back face (10b), b) forming an interlayer layer (15) of a crystalline material selected from III-V composite materials excluding III-N composite materials, germanium and silicon-germanium, said interlayer layer (15) being disposed directly on the support substrate (10) on the side of its front face (10a), c) supplying a donor substrate (400) of a single-crystal material having a first lattice parameter, a front face (400a) and a back face (400b);an intermediate layer (20) of an amorphous or polycrystalline material being disposed on the donor substrate (400), at least on the side of its front face (400a),d)the assembly of the support substrates (20) and donor (400) by their respective front faces (10a,400a), via a bonding interface (25),e)the transfer of a layer from the donor substrate (400), called the seed layer (40), to obtain a composite structure (150) comprising the support substrate (10), the intercalated layer (15), the intermediate layer (20) and the seed layer (40), said seed layer being intended to serve as a crystal seed for the epitaxy of a functional layer (50) of a monocrystalline III-V compound material, a peripheral periphery (10c) of the support substrate (10) being devoid of a seed layer (40) and an intermediate layer (20).; Method of manufacturing a composite structure (150) according to the preceding claim, further comprising: (f) the formation, by epitaxy, of the functional layer (50) in a single-crystal III-V composite material having a second lattice parameter identical to the first lattice parameter or differing from the latter by less than 2%, on the intercalated layer (15) at the level of the peripheral perimeter (10c) and on the seed layer (40). A manufacturing process according to one of the two preceding claims, wherein the interlayer layer (15) formed in step b) has a thickness greater than or equal to 50nm, preferably between 100nm and 1000nm. A manufacturing process according to one of the three preceding claims, comprising: - a step b'), after step b), comprising the formation of a bonding layer (30) on the interlayer layer (15), said bonding layer (30) being of an amorphous or polycrystalline material, in particular silicon oxide, and - a step e', after step e) and before step f), of removing the bonding layer (30) at the perpendicular edge (10c). Manufacturing method according to one of the four preceding claims, comprising a step g) of removing all or part of the functional layer (50) and the intercalated layer (15) at the level of the peripheral perimeter (10c), by mechanical lapping or by chemical etching.

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