Method for manufacturing a structure comprising at least two blocks on a substrate

Abstract

The invention relates to a method for manufacturing a composite structure, comprising the steps of: (a) forming a temporary substrate (20) comprising an intermediate substrate (2) and a plurality of blocks (P1, P2, P3) of a first material; (b) bonding via the block the temporary substrate to a receptor substrate (3) made of a second material different from the first material; and (c) removing the intermediate substrate (2) to transfer at least a portion of the block (P '1, P' 2, P '3) to the acceptor substrate. The receptor substrate comprises a main surface from which cavities (01, 02, 03) extend, and the receptor substrate is bonded to the temporary substrate on the main surface side such that each block is accommodated in the respective cavity. After the intermediate substrate has been removed, the free surface of the portion of the block is substantially aligned with the major surface of the acceptor substrate.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a structure including at least two pavés on a carrier substrate. Background Art

[0002] In the fields of microelectronics, optics or optoelectronics, the design of multilayer structures sometimes requires the transfer of pavés in the form of parts of layers of a donor substrate onto a carrier substrate or a receptor substrate.

[0003] This type of method is generally referred to as a pavage method and involves the transfer of parts of layers taken from a donor substrate to form one or more pavés arranged in a pattern or arranged at predetermined positions on a carrier substrate.

[0004] This pavage may be necessary due to the dimensional differences between the donor substrate and the carrier substrate. Specifically, due to such dimensional differences, it is not possible to transfer the entire layer of the donor substrate onto the carrier substrate.

[0005] A well-known layer transfer method is the Smart Cut TM method, in which by implanting atomic species in a donor substrate, a weakened zone defining the layer to be transferred is formed, the donor substrate is bonded to the carrier substrate, and the donor substrate is separated along the weakened zone to transfer the layer from the donor substrate to the carrier substrate. However, this method assumes that the donor substrate and the carrier substrate have the same dimensions.

[0006] Although silicon substrates with relatively large dimensions (usually 300 mm in diameter) are available, other materials of interest currently exist only in the form of bulk substrates with smaller dimensions (e.g., 10 cm or 15 cm in diameter). In addition, these materials of interest are sometimes particularly expensive, so it is desirable to minimize the potential waste formed during the transfer. This is especially true for III-V semiconductor materials, which include nitrides (e.g., for binary compounds, indium nitride (InN), gallium nitride (GaN) and aluminum nitride (AlN)), arsenides (e.g., for binary compounds, indium arsenide (InAs), gallium arsenide (GaAs) and aluminum arsenide (AlAs)) and phosphides (e.g., for binary compounds, indium phosphide (InP), gallium phosphide (GaP) and aluminum phosphide (AlP)).

[0007] Based on Smart Cut TMRather than transferring an entire layer of a donor substrate, the process solution involves obtaining one or more blocks from at least one donor substrate and transferring the blocks onto a first substrate to form a so-called pseudo-donor substrate. Weakening zones are formed in the individual blocks by implanting atomic seeds, the pseudo-donor substrate is bonded to a second substrate via the blocks, and the individual blocks are separated along the weakening zones to transfer a portion of each block onto the second substrate. The first substrate and the second substrate have the same dimensions.

[0008] Figure 1 A top view and a cross-sectional view of a carrier substrate S are shown, on which a plurality of blocks P1 - P9 from at least one donor substrate have been placed. In this example, there are nine blocks, which are distributed in three rows and three columns.

[0009] However, it is difficult to use a substrate carrying such blocks in a conventional microelectronic production line for manufacturing electronic components. Such a production line particularly includes lithography equipment and / or metrology equipment, and their operations are interrupted by the height difference between the main surface of the substrate and the free surface of the blocks. SUMMARY OF THE INVENTION

[0010] An object of the present application is to design a method for manufacturing a composite structure including at least two blocks on a carrier substrate, which is compatible with a traditional microelectronic production line.

[0011] To this end, the present application proposes a method for manufacturing a composite structure including at least two blocks on a substrate, the method comprising the following steps:

[0012] (a) forming a temporary substrate, the temporary substrate including an intermediate substrate and a plurality of blocks made of a first material placed on the intermediate substrate,

[0013] (b) assembling the temporary substrate with a receptor substrate made of a second material different from the first material via the blocks, and

[0014] (c) removing the intermediate substrate to transfer at least a portion of the blocks onto the receptor substrate to form the composite structure,

[0015] The method is characterized in that the receptor substrate includes a main surface, cavities extend from the main surface, the receptor substrate is assembled on the temporary substrate on the main surface side such that each block is received in a corresponding cavity, and wherein, after the intermediate substrate has been removed, the free surface of a portion of the block is substantially aligned with the main surface of the receptor substrate.

[0016] "Basic alignment" means that the surface of the block as a flat surface and the main surface of the receptor substrate are coplanar or parallel, and the separated distance (measured in a direction perpendicular to the surface) is between 1% and 10% of the thickness of the transferred portion. In the case of a non-zero distance, the surface of a portion of the block may be raised relative to the main surface of the receptor substrate, or conversely, the main surface of the receptor substrate may be raised relative to the surface of a portion of the block. Generally, it is ensured that the distance is less than about 50 nm.

[0017] In some embodiments, the step (a) of forming the temporary substrate includes forming a weakened zone in each block, which defines the corresponding portion of the block to be transferred, and the step (c) of removing the intermediate substrate includes separating the portions of each block along the weakened zone.

[0018] The formation of the weakened zone advantageously includes implanting atomic seeds in each block.

[0019] In some embodiments, the formation of the temporary substrate includes obtaining each block from at least one donor substrate made of a first material and placing each block on an intermediate substrate, each donor substrate having a diameter smaller than that of the intermediate substrate.

[0020] In some embodiments, the second material is advantageously a semiconductor material, such as silicon or silicon carbide, a piezoelectric material, or glass.

[0021] In some embodiments, the receptor substrate is a semiconductor-on-insulator substrate, which sequentially includes a base substrate, an electrically insulating layer, and a layer of a second material that defines the main surface of the receptor substrate, and a cavity is formed in the layer of the second material until the electrically insulating layer.

[0022] Alternatively, a cavity is formed in the surface region of the receptor substrate made of the second material.

[0023] At least a portion of the wall of at least one of the cavities may be advantageously covered with an electrically insulating film to electrically insulate the corresponding portion of the block from the receptor substrate.

[0024] In other embodiments, the receptor substrate includes at least one surface layer of a second material covered with an electrically insulating layer, and a cavity is formed in the electrically insulating layer.

[0025] Preferably, the temporary substrate can be assembled on the receptor substrate by molecular adhesion.

[0026] Particularly advantageously, the thickness of each block is between 20 μm and 1,000 μm, preferably between 100 μm and 700 μm, and the thickness of the transferred portion of each block is between 30 nm and 1.5 μm.

[0027] Then, the depth of each cavity can be between 30 nm and 1.5 μm.

[0028] In some embodiments, after step (c) of removing the intermediate substrate, the free surface of the portion of the block is raised relative to the main surface of the receptor substrate, and the method further includes a step of polishing the surface.

[0029] According to an advantageous embodiment, the first material is selected from:

[0030] - semiconductor materials such as III-V materials, in particular indium nitride (InN), gallium nitride (GaN), aluminum nitride (AlN), indium arsenide (InAs), gallium arsenide (GaAs), aluminum arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP) or aluminum phosphide (AlP), or group IV or IV-IV materials, in particular germanium or silicon carbide (SiC),

[0031] - piezoelectric materials such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), potassium sodium niobate (K x Na 1-x NbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), compounds of lead magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AlN) or aluminum scandium nitride (AlScN), and / or

[0032] - electrically insulating materials such as diamond, strontium titanate, yttria-stabilized zirconia or sapphire.

[0033] In some embodiments, the method includes forming at least one additional layer of a third material on each block by epitaxial growth before step (b) of assembling the temporary substrate and the receptor substrate.

[0034] The cavity is formed by chemically etching through a mask having an opening at the location of the cavity.

[0035] Preferably, the size of each cavity is designed to accommodate a single block, and the cavity has the same shape as the block.

[0036] Another object of the present application relates to a composite structure, the composite structure comprising:

[0037] - at least two blocks made of a first material, and

[0038] - a substrate, referred to as a receptor substrate, made of a second material different from the first material, the substrate having a main surface,

[0039] The composite structure is characterized in that the blocks are arranged in corresponding cavities that extend from the main surface in the receptor substrate such that the free surface of the blocks is substantially aligned with the main surface of the receptor substrate.

[0040] In some embodiments, the second material is a bulk semiconductor material such as silicon or silicon carbide, a piezoelectric material, or glass, or a stack of layers of multiple different semiconductor materials.

[0041] In other embodiments, the receptor substrate is a semiconductor-on-insulator substrate that sequentially includes a base substrate, an electrically insulating layer, and a layer of a second material that defines the main surface of the receptor substrate, and the cavities extend in the layer of the second material until the electrically insulating layer.

[0042] In other embodiments, the cavities extend in a surface region of the receptor substrate made of the second material.

[0043] In some embodiments, at least a portion of the walls of at least one of the cavities is covered with an electrically insulating film.

[0044] In other embodiments, the receptor substrate includes at least one surface layer of a second material covered with an electrically insulating layer, and the cavities are formed in the electrically insulating layer.

[0045] Advantageously, the first material is selected from:

[0046] - semiconductor materials such as group III-V materials, in particular indium nitride (InN), gallium nitride (GaN), aluminum nitride (AlN), indium arsenide (InAs), gallium arsenide (GaAs), aluminum arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP), or aluminum phosphide (AlP), or group IV or IV-IV materials, in particular germanium or silicon carbide (SiC),

[0047] - piezoelectric materials such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), potassium sodium niobate (K x Na 1-x NbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), compounds of lead magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AlN), or aluminum scandium nitride (AlScN), and / or

[0048] - electrically insulating materials such as diamond, strontium titanate, yttria-stabilized zirconia, or sapphire. Description of the Drawings

[0049] With reference to the accompanying drawings, other features and advantages will become apparent from the following detailed description, in which:

[0050] Figure 1 Schematic cross-sectional view of a composite structure according to an embodiment;

[0051] Figures 2A to 2D Illustrates the steps of forming a temporary substrate;

[0052] Figures 3A to 3H Illustrates different steps of preparing a receptor substrate and transferring blocks from the temporary substrate to the receptor substrate according to a first embodiment;

[0053] Figures 4A to 4F Illustrates different steps of preparing a receptor substrate and transferring blocks from the temporary substrate to the receptor substrate according to a second embodiment;

[0054] Figures 5A to 5F Illustrates different steps of preparing a receptor substrate and transferring blocks from the temporary substrate to the receptor substrate according to a third embodiment.

[0055] For readability, the drawings are not necessarily drawn to scale. In addition, the number of blocks schematically shown in the drawings is given by way of illustration only. Detailed Description

[0056] The present application proposes a method for manufacturing a composite structure including at least two blocks on a substrate such that the blocks can be placed in cavities of the substrate so that the surfaces of the blocks are substantially flush with the main surface of the substrate.

[0057] The blocks are formed of a first material preferably selected from:

[0058] - Semiconductor materials such as III-V materials, in particular indium nitride (InN), gallium nitride (GaN), aluminum nitride (AlN), indium arsenide (InAs), gallium arsenide (GaAs), aluminum arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP) or aluminum phosphide (AlP), or group IV or IV-IV materials, in particular germanium or silicon carbide (SiC),

[0059] - Piezoelectric materials such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), potassium sodium niobate (K x Na 1-x NbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), compounds of lead magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AlN) or aluminum scandium nitride (AlScN), and / or

[0060] - Electrically insulating materials such as diamond, strontium titanate, yttria-stabilized zirconia or sapphire.

[0061] Some of these materials are only available in the form of substrates with small dimensions (e.g., having a diameter of less than 150 mm to 200 mm). However, a composite structure as large as possible, e.g., on the order of 300 mm, is generally sought.

[0062] This size difference between the substrate made of the first material and the composite structure is compensated by forming a temporary structure that includes an intermediate substrate and a plurality of blocks made of the first material placed on the intermediate substrate, rather than directly transferring a layer of the first material onto the substrate of the composite structure.

[0063] To form the temporary substrate, blocks are obtained from at least one donor substrate made of the first material, and each block is placed on the intermediate substrate. Each donor substrate generally has a smaller diameter than the intermediate substrate, but the intermediate substrate has the same diameter as the composite structure. Depending on the stitching density on the substrate surface, multiple donor substrates may be required.

[0064] Depending on the composition of the first material, the thickness of each donor substrate can be between 20 μm and 1,000 μm, preferably between 100 μm and 700 μm. In principle, especially for the weakest materials, blocks that extend over the entire thickness of the donor substrate are cut from each donor substrate. As a result, the thickness of the blocks is generally equal to the thickness of the donor substrate and thus is generally between 20 μm and 1,000 μm, preferably between 100 μm and 700 μm.

[0065] In a method called "pick and place", the blocks can be placed on the intermediate substrate by a robot.

[0066] Since the intermediate substrate essentially acts as a temporary mechanical carrier for the blocks before the blocks are transferred to another substrate to form the composite structure, the intermediate structure can be made of any material hard enough to withstand the steps of the method. For example, without limitation, the intermediate substrate can be made of silicon.

[0067] In some embodiments, at least one additional layer can be grown on the blocks after the blocks have been placed on the intermediate substrate. The additional layer can be formed, for example, by epitaxially growing a third material on the first material. The third material can be the same as the first material, in which case the additional layer enables the blocks to be thickened. In other applications, the third material can be different from the first material. To maintain the crystal quality of the additional layer, the third material is preferably selected such that its lattice parameter and thermal expansion coefficient are close enough to those of the first material. For example, if the first material is InP, the third material can be InGaAs, InAlAs, GaAs, etc. Hereinafter, the stack composed of the blocks initially placed on the intermediate substrate and the subsequently formed additional layer will be referred to as a "block".

[0068] In some embodiments, a weakened zone is formed in each block to define a portion of the corresponding block of the substrate intended to be subsequently transferred to a composite structure. The thickness of the portion of the block to be transferred is advantageously between 30 nm and 1.5 μm.

[0069] In a manner known per se, such a weakened zone can be formed by implanting atomic species in each block. The species generally include hydrogen and / or helium.

[0070] The temporary substrate is then assembled with the receptor substrate via the blocks.

[0071] The receptor substrate includes a second material different from the first material.

[0072] Particularly advantageously, the second material is selected from semiconductor materials such as silicon or silicon carbide, piezoelectric materials or glass. The second material may optionally include a stack of several different semiconductor materials, such as Si / SiGe, Si / SiGe / Si, etc.

[0073] The receptor substrate is not necessarily composed of a single material. In some embodiments, the receptor substrate can thus be a semiconductor-on-insulator substrate. Such a substrate includes in sequence a base substrate, an electrically insulating layer and a layer of the second material. In other embodiments, the receptor substrate may include an electrically insulating layer covering the second material, such as silicon oxide.

[0074] The receptor substrate does not have a flat main surface but has cavities extending in the thickness of the receptor substrate from the main surface.

[0075] In the plane of the main surface of the receptor substrate, the dimensions of the cavities are slightly larger than the blocks (the cavities and the blocks preferably having the same shape) and are distributed in a pattern similar to that of the blocks, each cavity being intended to receive the corresponding block. Alternatively, the cavities can be intended to receive several adjacent blocks. In this case, the dimensions of the cavities are adapted to receive all the corresponding blocks.

[0076] The depth of the cavities is also less than the thickness of the blocks. When the temporary substrate is assembled on the receptor substrate, each block is thus received in the corresponding cavity at least in a portion of its thickness and adheres to the bottom of the cavity.

[0077] For example, if the blocks do not include a weakened zone, the depth of the cavities can be between 20 μm and 1,000 μm, preferably between 100 μm and 700 μm.

[0078] If the blocks have a weakened zone, the depth of the cavities can be approximately equal to the thickness of the layer to be transferred delimited by the weakened zone. For example, the depth of the cavities can be between 30 nm and 1.5 μm.

[0079] In some embodiments, a cavity is formed by etching a second material on the surface of a receptor substrate. To this end, a mask may be pre - formed on the surface of the receptor substrate to cover the areas to be protected. The mask may generally be made of silicon nitride or silicon oxide. The mask has an opening that defines the surface to be etched to form the cavity. Then, an etching process is performed, such as wet etching (the etchant may be HF, TMAH, KOH) or dry etching (e.g., reactive ion etching or RIE), to remove the second material. The etching time is selected according to the desired thickness of the cavity.

[0080] If the receptor substrate is a semiconductor - on - insulator substrate, the electrically insulating layer advantageously acts as an etch - stop layer, such that the cavity extends through the entire thickness of the layer of the second material until the electrically insulating layer.

[0081] In other embodiments, if the second material is covered with an electrically insulating layer, a cavity is formed by etching the material of the electrically insulating layer. In this case, the second material advantageously acts as an etch - stop layer, such that the cavity extends through the entire thickness of the electrically insulating layer until the second material. The remaining areas of the electrically insulating layer enable the electrical insulation of adjacent blocks.

[0082] In some embodiments, after the cavity has been etched, an electrically insulating layer is formed on the walls and bottom of the cavity. Such an electrically insulating layer may be formed, for example, by oxidizing the second material during annealing in an oxidizing atmosphere. Alternatively, the electrically insulating layer may be formed by a deposition method, such as chemical vapor deposition (CVD). The layer thus formed enables the electrical insulation of the block from the receptor substrate and the electrical insulation of adjacent blocks. The oxide layer may optionally act as a bonding layer for the block.

[0083] If the cavity has been formed in the electrically insulating layer covering the second material, it is possible to deposit an additional electrically insulating layer only on the bottom of the cavity to electrically insulate the block from the receptor substrate.

[0084] Finally, the intermediate substrate is removed to transfer at least a portion of the block onto the receptor substrate to form a composite structure.

[0085] In some embodiments, the intermediate substrate may be removed by removing material, for example, by grinding the intermediate substrate from the face opposite to the receptor substrate.

[0086] In other embodiments, if the block includes a weakened area, the block is separated along the weakened area, which separation may be induced by mechanical stress, thermal stress, and / or chemical stress. Then, the intermediate substrate and the remaining part of the block may be separated from the receptor substrate, and the part of the block that defines the weakened area is transferred onto the receptor substrate.

[0087] Preferably, the free surface of the portion of the block is slightly elevated relative to the free surface of the receptor substrate. For example, the free surface of the portion of the block protrudes from the free surface of the receptor substrate by a height between 1% and 10% of the total thickness of the transferred portion. The surface of the block can then be polished to remove areas that may have been damaged during implantation and to make the block of uniform thickness. The polishing can be chemical mechanical polishing (CMP). After polishing, the free surface of the block is substantially aligned with the free surface of the receptor substrate.

[0088] When the block or a portion of the block is received in the cavity, the composite structure formed by the receptor substrate and the block or the portion of the block has a flat surface. During subsequent steps implemented on the composite structure, in particular during lithography or metrology steps, overlay defects or measurement errors are thus avoided.

[0089] Figure 1 is a schematic cross-sectional view of a composite structure according to one embodiment. The structure includes blocks P1, P2, P3 made of a first material and a substrate 3 made of a second material. Each block is disposed in a respective cavity of the substrate 3 formed in the main surface of the substrate 3 such that the free surface of the block is substantially aligned (coplanar) with the surface of the substrate 3.

[0090] As can be seen more clearly in the insert, which shows an enlarged view of the block P3 in its cavity, the free surface of each block is at a height h relative to the surface of the substrate 3. The height h can be zero (the free surface of the block and the main surface of the substrate are coplanar), positive (the block is then slightly elevated relative to the main surface of the substrate), or negative (the block is then slightly recessed relative to the main surface of the substrate). As an absolute value, the height h is typically between 1% and 10% of the total thickness of the transferred portion of the block.

[0091] Figures 2A to 2D Illustrates the steps of forming a temporary substrate.

[0092] Reference Figure 2A , the blocks P1, P2, P3 are cut from a donor substrate 1 made of a first material. Typically, in order not to weaken the blocks, the blocks are cut through the entire thickness of the donor substrate.

[0093] Reference Figure 2B , each block P1, P2, P3 is placed on an intermediate substrate 2. As described above, the intermediate substrate serves as a mechanical carrier for the blocks before the blocks are transferred onto the final substrate to form the composite structure. The blocks can be placed individually (block by block) by a robot.

[0094] In some embodiments, reference Figure 2C, the weakening zones 10 can be formed in the respective blocks P1, P2, P3 placed on the intermediate substrate 2 to define surface portions P'1, P'2, P'3. The weakening zones can be formed in particular by implanting atomic seeds (schematically shown by arrows) in the blocks.

[0095] In some embodiments, referring to Figure 2D , an additional layer 11 can be formed on the blocks P1, P2, P3 placed on the intermediate substrate 2. The additional layer can advantageously be formed by epitaxial growth on the respective blocks.

[0096] Depending on the case, in the remainder of the method for forming the composite structure, Figure 2B , Figure 2C and Figure 2D the substrate 20 illustrated therein is used as a temporary substrate. Figure 2C and Figure 2D The embodiments in

[0097] can optionally be combined. In this case, advantageously, the additional layer is produced before implanting the atomic seeds to prevent the thermal budget of the additional layer growth from causing premature breakage of the blocks along the weakening zones.

[0098] Figures 3A to 3H illustrates the different steps for preparing the receptor substrate and transferring the blocks from the temporary substrate to the receptor substrate when the receptor substrate is a semiconductor-on-insulator substrate.

[0099] Referring to Figure 3A , the receptor substrate 3 successively includes a base substrate 30, an electrically insulating layer 31 (such as silicon oxide (also known as the buried oxide layer)) and a layer 32 of a second material.

[0100] Referring to Figure 3B , a mask 4 is formed on the layer 32, and the mask has an opening at the position where the cavity is to be formed.

[0101] Referring to Figure 3C , (preferably over the entire thickness of the layer 32) the second material exposed by the opening in the mask 4 is etched to form cavities C1, C2, C3. The electrically insulating layer 31 effectively forms an etch stop layer.

[0102] Referring to Figure 3D , the mask 4 is removed to expose the surface of the remaining layer 32. The substrate thus obtained can be used as a receptor substrate for accommodating the blocks.

[0103] In an alternative embodiment, an electrically insulating layer 33 may be formed on the walls of the cavity before assembling the receptor substrate and the temporary substrate. Thus, the walls and bottom of the cavity are covered with an electrically insulating material, which allows the blocks to be transferred into the cavity to be electrically insulated from the portions of layer 32 extending between the cavity and the base substrate 30.

[0104] Reference Figure 3F , assemble the receptor substrate 3 and the temporary substrate 20, and place the blocks P1, P2, P3 and the corresponding cavities C1, C2, C3 facing each other (in this figure, substrates from Figure 3D are shown, but alternatively substrates from Figure 3E may be used).

[0105] As Figure 3G illustrates, the adhesion between the substrate 3 and the substrate 20 occurs via the bottoms of the blocks and the cavities.

[0106] Reference Figure 3H , remove the intermediate substrate. In the illustrated embodiment, the blocks have weakening zones 11. Thus, the intermediate substrate and the remaining portions of the blocks are removed by separating along the weakening zones 11. Thus, only the portions P'1, P'2, P'3 of the blocks are transferred onto the receptor substrate.

[0107] In other embodiments (not illustrated), the intermediate substrate may be removed by grinding the substrate from the face opposite the receptor substrate until reaching the main surface of the substrate 3.

[0108] Figures 4A to 4F Illustrates the different steps for preparing the receptor substrate and transferring the blocks from the temporary substrate onto the receptor substrate when the receptor substrate is a bulk substrate.

[0109] Reference Figure 4A , the receptor substrate 3 is a bulk substrate made of a second material.

[0110] Reference Figure 4B , form a mask 4 on the substrate 3, the mask having openings at the positions where the cavities are to be formed.

[0111] Reference Figure 4C , etch the second material exposed by the openings in the mask 4 to form the cavities C1, C2, C3. Adjust the etching time according to the desired depth of the cavities.

[0112] Then remove the mask 4 to expose the surface of the substrate 3. The substrate thus obtained can be used as a receptor substrate for accommodating the blocks.

[0113] As Figure 4DAs illustrated, in an alternative embodiment, before assembling the receptor substrate and the temporary substrate, an electrically insulating layer 33 may be formed on the surface of the substrate 3 to cover the walls and the bottom of the cavity. The layer 33 makes it possible to electrically insulate the blocks that will be transferred into the cavity from the rest of the substrate 3.

[0114] Reference Figure 4E , assemble the receptor substrate 3 and the temporary substrate 20, and place the blocks P1, P2, P3 and the corresponding cavities C1, C2, C3 facing each other (in this figure, a substrate from Figure 4D is shown, but the electrically insulating layer 33 may optionally be eliminated).

[0115] The adhesion between the substrate 3 and the substrate 20 occurs via the bottoms of the blocks and the cavities.

[0116] Reference Figure 4F , remove the intermediate substrate. In the illustrated embodiment, the blocks have weakening zones 11. Thus, the intermediate substrate and the rest of the blocks are removed by separating along the weakening zones 11. Thus, only the portions P'1, P'2, P'3 of the blocks are transferred onto the receptor substrate.

[0117] In other embodiments (not illustrated), the intermediate substrate may be removed by grinding the substrate from the face opposite to the receptor substrate until reaching the main surface of the substrate 3.

[0118] Figures 5A to 5F Illustrates different steps for preparing a receptor substrate and transferring blocks from a temporary substrate onto the receptor substrate when the receptor substrate includes a substrate made of a second material covered with an electrically insulating layer.

[0119] Reference Figure 5A , the receptor substrate 3 includes a bulk substrate 30 made of a second material covered with an electrically insulating layer 34.

[0120] Reference Figure 5B , form a mask 4 on the layer 34, the mask having openings at the positions where the cavities are to be formed.

[0121] Reference Figure 5C , etch the electrically insulating material exposed by the openings in the mask 4 (preferably over the entire thickness of the layer 34) to form the cavities C1, C2, C3. The substrate 30 effectively forms an etch stop layer.

[0122] Reference Figure 5D , remove the mask 4 to expose the surface of the layer 34. The resulting substrate can be used as a receptor substrate for accommodating the blocks.

[0123] Reference Figure 5E , assemble the receptor substrate 3 and the temporary substrate 20, and place the blocks P1, P2, P3 and the corresponding cavities C1, C2, C3 facing each other.

[0124] The adhesion between the substrate 3 and the substrate 20 occurs via the bottoms of the blocks and cavities.

[0125] Reference Figure 5F , the intermediate substrate is removed. In the illustrated embodiment, the block has a weakened zone 11. Thus, the intermediate substrate and the remaining part of the block are removed by separating along the weakened zone 11. Thus, only the portions P'1, P'2, P'3 of the block are transferred onto the receptor substrate.

[0126] In other embodiments (not illustrated), the intermediate substrate can be removed by grinding the substrate from the face opposite to the receptor substrate until reaching the main surface of the substrate 3.

Claims

1. A method for manufacturing a composite structure including at least two blocks on a substrate, the method comprising the following steps: (a) forming a temporary substrate (20), the temporary substrate (20) including an intermediate substrate (2) and a plurality of blocks (P1, P2, P3) made of a first material placed on the intermediate substrate (2), (b) assembling the temporary substrate (20) with a receptor substrate (3) made of a second material different from the first material via the blocks (P1, P2, P3), and (c) removing the intermediate substrate (2) to transfer at least a part (P'1, P'2, P'3) of the blocks to the receptor substrate (3) to form the composite structure, wherein the receptor substrate (3) includes a main surface, cavities (C1, C2, C3) extend from the main surface, the receptor substrate (3) is assembled on the temporary substrate (20) on the main surface side such that each block (P1, P2, P3) is received in a corresponding cavity (C1, C2, C3), and wherein, after the intermediate substrate (2) has been removed, the free surfaces of the parts (P'1, P'2, P'3) of the blocks are substantially aligned with the main surface of the receptor substrate (3).

2. The method according to claim 1, wherein The step (a) of forming the temporary substrate (20) includes forming a weakened area (10) in each block (P1, P2, P3), the weakened area (10) defining the corresponding part (P’1, P’2, P’3) of the block to be transferred, and the step (c) of removing the intermediate substrate (2) includes separating the parts (P’1, P’2, P’3) of each block along the weakened area (10).

3. The method according to claim 2, wherein The formation of the weakened area (10) includes implanting atomic species in each block (P1, P2, P3).

4. The method according to any one of claims 1 to 3, wherein The formation of the temporary substrate (20) includes obtaining each block (P1, P2, P3) from at least one donor substrate (1) made of the first material and placing each block (P1, P2, P3) on the intermediate substrate (2), each donor substrate (1) having a diameter smaller than that of the intermediate substrate (2).

5. The method according to one of claims 1 to 4, wherein The second material is a semiconductor material, such as silicon or silicon carbide, a piezoelectric material or glass.

6. The method according to claim 5, wherein The receptor substrate (3) is a semiconductor-on-insulator substrate, the semiconductor-on-insulator substrate sequentially including a base substrate (30), an electrically insulating layer (31) and a layer (32) of the second material defining the main surface of the receptor substrate, and the cavities (C1, C2, C3) are formed in the layer (32) of the second material until the electrically insulating layer (31).

7. The method according to claim 5, wherein The cavities (C1, C2, C3) are formed in a surface area of the receptor substrate (3) made of the second material.

8. The method according to one of claims 6 and 7, wherein, At least a part of the wall of at least one of the cavities (C1, C2, C3) is covered with an electrically insulating film (33) to electrically insulate the corresponding part (P'1, P'2, P'3) of the block from the receptor substrate (3).

9. The method according to claim 5, wherein The receptor substrate (3) includes at least one surface layer of the second material covered with an electrically insulating layer (34), and the cavities (C1, C2, C3) are formed in the electrically insulating layer (34).

10. The method according to one of claims 1 to 9, wherein, The temporary substrate (20) is assembled on the receptor substrate (3) by molecular adhesion.

11. The method according to one of claims 1 to 10, wherein, The thickness of each block (P1, P2, P3) is between 20 μm and 1,000 μm, preferably between 100 μm and 700 μm, and the thickness of the transferred part (P'1, P'2, P'3) of each block is between 30 nm and 1.5 μm.

12. The method according to claim 11, wherein, The depth of each cavity (C1, C2, C3) is between 30 nm and 1.5 μm.

13. The method according to one of claims 1 to 12, wherein, After the step (c) of removing the intermediate substrate (2), the free surface of the part (P'1, P'2, P'3) of the block rises relative to the main surface of the receptor substrate (3), and the method further includes a step of polishing the surface.

14. The method according to one of claims 1 to 13, wherein, The first material is selected from: - semiconductor materials, such as group III-V materials, in particular indium nitride InN, gallium nitride GaN, aluminum nitride AlN, indium arsenide InAs, gallium arsenide GaAs, aluminum arsenide AlAs, indium phosphide InP, gallium phosphide GaP or aluminum phosphide AlP, or group IV or IV-IV materials, in particular germanium or silicon carbide SiC, - Piezoelectric materials, such as lithium tantalate LiTaO3, lithium niobate LiNbO3, potassium sodium niobate K x Na 1-x NbO3 or KNN, barium titanate BaTiO3, quartz, lead zirconate titanate PZT, compounds of lead magnesium niobate and lead titanate PMN-PT, zinc oxide ZnO, aluminum nitride AlN or aluminum scandium nitride AlScN, and / or - electrically insulating materials, such as diamond, strontium titanate, yttria-stabilized zirconia or sapphire.

15. The method according to any one of claims 1 to 14, the method including forming at least one additional layer (11) of a third material on each block by epitaxial growth before the step (b) of assembling the temporary substrate (20) and the receptor substrate (3).

16. The method according to one of claims 1 to 15, wherein The cavities (C1, C2, C3) are formed by chemically etching through a mask (4) having an opening at the position of the cavity.

17. The method according to one of claims 1 to 16, wherein, The size of each cavity (C1, C2, C3) is designed to accommodate a single block, and the cavity has the same shape as the block.

18. A composite structure, the composite structure including: - at least two blocks (P'1, P'2, P'3) made of a first material, and - a substrate (3), the substrate (3) being called a receptor substrate, the substrate (3) being made of a second material different from the first material, the substrate (3) having a main surface, The composite structure is characterized in that the blocks (P'1, P'2, P'3) are arranged in corresponding cavities (C1, C2, C3) that extend from the main surface in the receptor substrate (3), such that the free surfaces of the blocks (P'1, P'2, P'3) are substantially aligned with the main surface of the receptor substrate (3).

19. The structure according to claim 18, wherein, The second material is a bulk semiconductor material such as silicon or silicon carbide, a piezoelectric material or glass, or a stack of layers of multiple different semiconductor materials.

20. The structure according to claim 19, wherein, The receptor substrate (3) is a semiconductor-on-insulator substrate, which sequentially includes a base substrate (30), an electrically insulating layer (31), and a layer (32) of the second material that defines the main surface of the receptor substrate, and the cavities (C1, C2, C3) extend in the layer of the second material until the electrically insulating layer.

21. The structure according to claim 19, wherein, The cavities (C1, C2, C3) extend in the surface region of the receptor substrate (3) made of the second material.

22. The structure according to one of claims 20 and 21, wherein, At least a part of the wall of at least one of the cavities (C1, C2, C3) is covered with an electrically insulating film (33).

23. The structure according to claim 19, wherein, The receptor substrate (3) includes at least one surface layer of the second material covered with an electrically insulating layer (34), and the cavities (C1, C2, C3) are formed in the electrically insulating layer (34).

24. The structure according to one of claims 18 to 23, wherein, The first material is selected from: - semiconductor materials, such as group III-V materials, in particular indium nitride InN, gallium nitride GaN, aluminum nitride AlN, indium arsenide InAs, gallium arsenide GaAs, aluminum arsenide AlAs, indium phosphide InP, gallium phosphide GaP or aluminum phosphide AlP, or group IV or IV-IV materials, in particular germanium or silicon carbide SiC, - Piezoelectric materials, such as lithium tantalate LiTaO3, lithium niobate LiNbO3, potassium sodium niobate K x Na 1-x NbO3 or KNN, barium titanate BaTiO3, quartz, lead zirconate titanate PZT, compounds of lead magnesium niobate and lead titanate PMN-PT, zinc oxide ZnO, aluminum nitride AlN or aluminum scandium nitride AlScN, and / or - electrically insulating materials, such as diamond, strontium titanate, yttria-stabilized zirconia or sapphire.

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