METHOD FOR MANUFACTURING A STRUCTURE COMPRISING AT LEAST TWO PANELS ON A SUBSTRATE

Abstract

The invention relates to a method for manufacturing a composite structure, comprising: (a) forming a temporary substrate (20) comprising an intermediate substrate (2) and a plurality of blocks (P1, P2, P3) of a first material, (b) assembling the temporary substrate with a receiving substrate (3) made of a second material different from the first material via said blocks, and (c) removing the intermediate substrate (2) to transfer at least a portion (P'1, P'2, P'3) of the blocks onto the receiving substrate. The receiving substrate comprises a main surface from which cavities (C1, C2, C3) extend, the receiving substrate being assembled to the temporary substrate on the side of said main surface such that each block is received in a respective cavity. After removing the intermediate substrate, the free surface of the block portions is substantially aligned with the main surface of the receiving substrate. Figure for abstract: Fig 3F

Description

Title of the invention: METHOD FOR MANUFACTURING A STRUCTURE COMPRISING AT LEAST TWO PAVING PANELS ON A SUBSTRATE Technical field

[0001] The invention relates to a method of manufacturing a structure comprising at least two blocks on a support substrate. STATE OF THE ART

[0002] In the field of microelectronics, optics or optoelectronics, the design of multilayer structures sometimes requires transferring tiles in the form of portions of a layer from a donor substrate onto a support substrate or receiving substrate.

[0003] This type of process is generally referred to as a paving process, and involves a partial transfer of a layer taken from the donor substrate to form one or more tiles arranged in a pattern or at a predetermined location on the support substrate.

[0004] Such tiling may be made necessary by a difference in size between the donor substrate and the support substrate. Indeed, due to this difference in size, it is not possible to transfer an entire layer of the donor substrate onto the support substrate.

[0005] A well-known layer transfer method is the Smart Cut™ method, in which a weakening zone delimiting the layer to be transferred is formed by implantation of atomic species in the donor substrate, the donor substrate is bonded to the support substrate, and the donor substrate is detached along the weakening zone to transfer the layer from the donor substrate to the support substrate. However, this method assumes that the donor substrate and the support substrate have the same size.

[0006] However, while silicon substrates are available with a relatively large size, typically a diameter of 300 mm, other materials of interest currently only exist in the form of smaller bulk substrates, for example 10 or 15 cm in diameter. Furthermore, these materials of interest are sometimes particularly expensive, so that it is desirable to minimize any waste formed during the transfer. This is the case in particular for III-V semiconductor materials, including nitrides (for example, for binary compounds, indium nitride (InN), gallium nitride (GaN) and aluminum nitride (AIN)), arsenides (for example, 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 (A1P)).

[0007] Instead of transferring an entire layer of the donor substrate, a solution based on the Smart Cut™ process consists of removing one or more tiles from at least one donor substrate and transferring said tiles to a first substrate, to form a so-called pseudo-donor substrate, forming by implantation of atomic species a weakening zone in each tile, bonding the pseudo-donor substrate to a second substrate via the tiles, and detaching each tile along the weakening zone so as to transfer a portion of each tile to the second substrate. The first and second substrates have an identical size.

[0008] [Fig.l] represents a top view and a sectional view of a support substrate S on which a plurality of tiles P1-P9 of at least one donor substrate have been arranged. In this example, there are nine tiles and they are distributed in three rows and three columns.

[0009] However, a substrate supporting such tiles is difficult to use in conventional microelectronics manufacturing lines for manufacturing electronic components. Such manufacturing lines include in particular photolithography and / or metrology equipment, the operation of which is disturbed by the differences in height between the main surface of the substrate and the free surface of the tiles. BRIEF DESCRIPTION OF THE INVENTION

[0010] An aim of the invention is to design a method for manufacturing a composite structure comprising at least two blocks on a support substrate, which is compatible with conventional microelectronics manufacturing lines.

[0011] To this end, the invention proposes a method for manufacturing a composite structure comprising at least two blocks on a substrate, comprising:

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

[0013] (b) assembling the temporary substrate with a receiving substrate in a second material different from the first material by means of said paving stones, and

[0014] (c) removing the intermediate substrate so as to transfer at least a portion of the paving stones on the receiving substrate to form the composite structure,

[0015] said method being characterized in that the receiving substrate comprises a main surface from which cavities extend, the receiving substrate being assembled to the temporary substrate on the side of said main surface so that each tile is received in a respective cavity and in that, after removal of the intermediate substrate, the free surface of the tile portions is substantially aligned with the main surface of the receiving substrate.

[0016] By "substantially aligned" is meant that the surface of the blocks and the main surface of the receiving substrate, which are planar surfaces, are either coplanar or parallel and separated by a distance (measured in a direction perpendicular to said surfaces) of between 1% and 10% of the thickness of the transferred portion. In the case of a non-zero distance, the surface of the block portions may be in relief relative to the main surface of the receiving substrate or, conversely, the main surface of the receiving substrate may be in relief relative to the surface of the block portions. In general, it is ensured that said distance is less than approximately 50 nm.

[0017] In some embodiments, step (a) of forming the temporary substrate comprises forming a weakening zone of each tile delimiting a respective tile portion to be transferred, and step (c) of removing the intermediate substrate comprises detaching each tile portion along said weakening zone.

[0018] The formation of said weakening zone advantageously comprises an implantation of atomic species within each block.

[0019] In some embodiments, forming said temporary substrate comprises removing each tile from at least one donor substrate of the first material and placing each tile on the intermediate substrate, each donor substrate having a diameter less than the diameter 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 receiving substrate is a semiconductor-on-insulator type substrate successively comprising a base substrate, an electrically insulating layer and a layer of the second material defining the main surface of the receiving substrate, and the cavities are formed in the layer of the second material up to the electrically insulating layer.

[0022] Alternatively, the cavities are formed in a surface region of the receiving substrate made of the second material.

[0023] At least a portion of the walls of at least one of said cavities may advantageously be covered with an electrically insulating film, so as to electrically insulate the respective portion of the block from the receiving substrate.

[0024] In other embodiments, the receiving substrate comprises at least one surface layer of the second material covered with an electrically insulating layer and the cavities are formed in said electrically insulating layer.

[0025] Preferably, the assembly of the temporary substrate on the receiving substrate can be carried out by molecular adhesion.

[0026] In a particularly advantageous manner, each block has a thickness of between 20 μm and 1000 μm, preferably between 100 μm and 700 μm, and the transferred portion of each block has a thickness of between 30 nm and 1.5 μm.

[0027] Each cavity can then have a depth of between 30 nm and 1.5 pm.

[0028] In certain embodiments, at the end of step (c) of removing the intermediate substrate, the free surface of the paving portions is in relief relative to the main surface of the receiving substrate, the method further comprising a step of polishing said surfaces.

[0029] According to advantageous embodiments, the first material is chosen from:

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

[0031] - a piezoelectric material, such as lithium tantalate (LiTaO3), lithium niobate (LiO3), lithium (LiNbO3), potassium sodium niobate (KxNai_xNbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a compound of lead magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN), and / or

[0032] - an electrically insulating material, such as diamond, strontium titanate, yttria-containing zirconia or sapphire.

[0033] In certain embodiments, the method comprises, before step (b) of assembling the temporary substrate and the receiving substrate, the formation by epitaxy of at least one additional layer of a third material on each tile.

[0034] The cavities may be formed by chemical etching through a mask having openings at the location of said cavities.

[0035] Preferably, each cavity is sized to receive a single paving stone, said cavity having a shape identical to that of said paving stone.

[0036] Another object of the invention relates to a composite structure comprising:

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

[0038] - a substrate, called the receiving substrate, made of a second material distinct from the first material, having a main surface,

[0039] said composite structure being characterized in that said blocks are arranged in respective cavities extending into the receiving substrate from the main surface, such that a free surface of the blocks is substantially aligned with the main surface of the receiving 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 multiple layers of different semiconductor materials.

[0041] In other embodiments, the receiving substrate is a semiconductor-on-insulator type substrate successively comprising a base substrate, an electrically insulating layer and a layer of the second material defining the main surface of the receiving substrate, and the cavities extend into the layer of the second material as far as the electrically insulating layer.

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

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

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

[0045] Particularly advantageously, the first material is chosen from:

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

[0047] - a piezoelectric material, such as lithium tantalate (LiTaO3), lithium niobate (LiO3), lithium (LiNbO3), potassium sodium niobate (KxNahxNbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a compound of lead magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN), and / or

[0048] - an electrically insulating material, such as diamond, strontium titanate, yttria-containing zirconia or sapphire. BRIEF DESCRIPTION OF THE FIGURES

[0049] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:

[0050] - [Fig.l] is a schematic sectional view of a composite structure according to a embodiment of the invention;

[0051] - Figures 2A to 2D illustrate steps in the formation of the temporary substrate;

[0052] - Figures 3A to 3H illustrate different steps of preparation of the receiving substrate and transferring the tiles from the temporary substrate to the receiving substrate, according to a first embodiment of the invention;

[0053] - Figures 4A to 4F illustrate different steps of preparation of the receiving substrate and transferring the tiles from the temporary substrate to the receiving substrate, according to a second embodiment of the invention;

[0054] - Figures 5A to 5F illustrate different steps of preparation of the receiving substrate and transferring the tiles from the temporary substrate to the receiving substrate, according to a third embodiment of the invention.

[0055] For reasons of readability, the drawings are not necessarily drawn to scale. Furthermore, the number of blocks shown diagrammatically in the drawings is given for illustration purposes only. DETAILED DESCRIPTION OF EMBODIMENTS

[0056] The invention provides a method for manufacturing a composite structure comprising at least two blocks on a substrate making it possible to deposit the blocks in cavities of said substrate, so as to make the surface of the blocks substantially flush with the main surface of the substrate.

[0057] The blocks are formed from a first material, which is preferably chosen from:

[0058] - a semiconductor material, such as a III-V material, in particular nitride indium nitride (InN), gallium nitride (GaN), aluminum nitride (AIN), indium arsenide (InAs), gallium arsenide (GaAs), aluminum arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP) or aluminum phosphide (AlP), or a material IV or IV-IV, including germanium or silicon carbide (SiC),

[0059] - a piezoelectric material, such as lithium tantalate (LiTaO3), lithium niobate (LiO3), lithium (LiNbO3), potassium sodium niobate (KxNahxNbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a compound of lead magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN), and / or

[0060] - an electrically insulating material, such as diamond, strontium titanate, yttria-containing zirconia or sapphire.

[0061] Some of these materials are only available in the form of small substrates, for example having a diameter of less than 150 or 200 mm. On the other hand, it is generally sought to form a composite structure having the largest possible size, for example of the order of 300 mm.

[0062] This difference in size between the substrate of the first material and the structure composite is compensated by the fact that a direct transfer of a layer of the first material onto the substrate of the composite structure is not carried out, but that a temporary substrate is formed comprising an intermediate substrate and a plurality of blocks of the first material arranged on the intermediate substrate.

[0063] To form said temporary substrate, paving stones are taken from at least one donor substrate of the first material and each paving stone is placed on an intermediate substrate. Each donor substrate typically has a diameter smaller than the diameter of the intermediate substrate, but the diameter of the intermediate substrate is identical to that of the composite structure. Depending on the paving density at the surface of the substrate, it may be necessary to use several donor substrates.

[0064] Depending on the composition of the first material, each donor substrate has a thickness of between 20 μm and 1000 μm, preferably between 100 μm and 700 μm. In principle, particularly for the most fragile materials, blocks extending over the entire thickness of the donor substrate are cut from each donor substrate. Consequently, the thickness of the blocks is generally equal to the thickness of the donor substrate(s), and is therefore typically between 20 μm and 1000 μm, preferably between 100 μm and 700 μm.

[0065] The placement of the paving stones on the intermediate substrate can be carried out by a robot, in a process known as “Pick and place”.

[0066] The intermediate substrate essentially serving as a temporary mechanical support for the paving stones before their transfer to another substrate to form the composite structure, the intermediate substrate may be made of any material having sufficient rigidity to support the steps of the process. For example, but in a non-limiting manner, the intermediate substrate may be made of silicon.

[0067] In some embodiments, at least one additional layer may be grown on the tiles after they have been placed on the intermediate substrate. Said additional layer may be formed, for example, by epitaxy of a third material on the first material. The third material may be identical to the first material, in which case the additional layer makes it possible to thicken the tiles. In other applications, the third material may be different from the first material. To preserve the crystalline quality of the additional layer, the third material is preferably chosen to have a lattice parameter and a coefficient of thermal expansion sufficiently close to those of the first material. For example, if the first material is InP, the third material may be InGaAs, InAlAs, GaAs, ...In the rest of the text, we will call "paving" the stack consisting of the paving initially placed on the intermediate substrate and the additional layer(s) formed subsequently.

[0068] In some embodiments, a weakening zone is formed in each paving stone so as to delimit a respective paving stone portion intended to be transferred by the continued on the substrate of the composite structure. The thickness of said portion of block to be transferred is advantageously between 30 nm and 1.5 pm.

[0069] In a manner known per se, such a weakening zone can be formed by implantation of atomic species within each block. Said species typically comprise hydrogen and / or helium.

[0070] The temporary substrate is then assembled with a receiving substrate by means of said blocks.

[0071] The receiving substrate comprises a second material different from the first material.

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

[0073] The receiving substrate is not necessarily made of a single material. Thus, in certain embodiments, the receiving substrate may be a semiconductor-on-insulator type substrate. Such a substrate successively comprises a base substrate, an electrically insulating layer and a layer of the second material. In other embodiments, the receiving substrate may comprise an electrically insulating layer, for example a silicon oxide, covering the second material.

[0074] According to the invention, the receiving substrate does not have a planar main surface but has cavities which extend into the thickness of the receiving substrate from said main surface.

[0075] The cavities have, in the plane of the main surface of the receiving substrate, a size slightly larger than that of the paving stones (cavities and paving stones preferably having an identical shape) and are distributed according to a pattern similar to that of the paving stones, each cavity being intended to receive a respective paving stone. Alternatively, a cavity may be intended to receive several adjacent paving stones. In this case, the size of said cavity is adapted to receive all of the respective paving stones.

[0076] The cavities also have a depth less than the thickness of the paving stones. Thus, when assembling the temporary substrate on the receiving substrate, each paving stone is received over at least part of its thickness in a respective cavity and adheres to the bottom of said cavity.

[0077] For example, in the case where the paving stones do not include a weakening zone, the depth of the cavities may be between 20 pm and 1000 pm, preferably between 100 pm and 700 pm.

[0078] In the case where the paving stones have a weakening zone, the depth of the cavities may be approximately equal to the thickness of the layer to be transferred delimited by the weakening zone. For example, the depth of the cavities may be between 30 nm and 1.5 pm.

[0079] In some embodiments, the cavities are formed by etching the second material, which is located on the surface of the receiving substrate. For this purpose, a mask may be formed beforehand on the surface of the receiving substrate so as to cover the areas to be protected. Said mask may typically be made of nitride or silicon oxide. The mask has openings defining the surface to be etched to form the cavities. The etching is then carried out, for example a wet etching (the etching agent may be HF, TMAH, KOH) or dry etching (for example a reactive ion etching, RIE, acronym for the English term "reactive ion etching") to remove the second material. The duration of the etching is chosen according to the desired thickness for the cavities.

[0080] In the case where the receiving substrate is a semiconductor-on-insulator type substrate, the electrically insulating layer advantageously serves as an etching stop layer, so that the cavities extend over the entire thickness of the layer of the second material, up to the electrically insulating layer.

[0081] In other embodiments, if the second material is covered with an electrically insulating layer, the cavities are formed by etching the material of said electrically insulating layer. In this case, the second material advantageously serves as an etch stop layer, so that the cavities extend over the entire thickness of the electrically insulating layer, up to the second material. The remaining areas of the electrically insulating layer make it possible to electrically insulate adjacent tiles.

[0082] In some embodiments, after etching the cavities, an electrically insulating layer is formed on the wall and the bottom of the cavities. Such an electrically insulating layer may for example be formed by oxidation of the second material during annealing in an oxidizing atmosphere. Alternatively, the electrically insulating layer may be formed by a deposition process, for example chemical vapor deposition (CVD). The layer thus formed makes it possible to electrically insulate the tiles from the receiving substrate and to electrically insulate adjacent tiles. The oxide layer may optionally fulfill the function of a bonding layer for the tiles.

[0083] In the case where the cavities have been formed in an electrically insulating layer covering the second material, it is possible to deposit an additional electrically insulating layer only on the bottom of the cavities, in order to electrically insulate the blocks from the receiving substrate.

[0084] Finally, the intermediate substrate is removed so as to transfer at least a portion of the paving stones onto the receiving substrate to form the composite structure.

[0085] In some embodiments, removal of the intermediate substrate may be produced by removing material, for example by grinding the intermediate substrate on its face opposite the receiving substrate.

[0086] In other embodiments, if the tiles comprise a weakening zone, a detachment of the tiles is implemented along the weakening zone, which can be initiated by a mechanical, thermal and / or chemical stress. The intermediate substrate and the remainder of the tiles can then be detached from the receiving substrate, the portion of the tiles delimiting the weakening zone being transferred to the receiving substrate.

[0087] Preferably, the free surface of the paving stone portions is slightly raised relative to the free surface of the receiving substrate. For example, the free surface of the paving stone portions protrudes by a height of between 1% and 10% of the total thickness of the transferred portion from the free surface of the receiving substrate. The surface of the paving stones can then be polished to remove any area damaged by the implantation and to standardize the thickness of the paving stones. Said polishing can be chemical mechanical polishing (CMP). At the end of the polishing, the free surface of the paving stones is substantially aligned with the free surface of the receiving substrate.

[0088] The blocks or portions of blocks being housed in the cavities, the composite structure formed from the receiving substrate and the blocks or portions of blocks has a flat surface. During the subsequent steps implemented on said composite structure, in particular photolithography or metrology steps, alignment defects (known as "overlay" in English terminology) or measurement errors are thus avoided.

[0089] [Fig.l] is a schematic sectional view of a composite structure according to one embodiment of the invention. Said structure comprises blocks P1, P2, P3 of the first material and a substrate 3 of the second material. Each block is arranged in a respective cavity of the substrate 3 formed in the main surface of said substrate 3, so that the free surface of the blocks is substantially aligned (coplanar) with the surface of the substrate 3.

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

[0091] Figures 2A to 2D illustrate steps in the formation of the temporary substrate.

[0092] With reference to [Fig.2A], paving stones PI, P2, P3 are cut from a donor substrate 1 of the first material. In general, to avoid weakening the paving stones, the paving stones are cut from the entire thickness of the donor substrate.

[0093] With reference to [Fig.2B], each paving stone P1, P2, P3 is placed on an intermediate substrate 2. As indicated above, said intermediate substrate has a function of mechanical support for the paving stones before their transfer to the final substrate to form the composite structure. The paving stones can be placed individually (paving stone by paving stone) using a robot.

[0094] In certain embodiments, with reference to [Fig.2C], a weakening zone 10 can be formed in each block PI, P2, P3 placed on the intermediate substrate 2, so as to delimit a surface portion P' 1, P'2, P'3. The weakening zone can in particular be formed by implantation of atomic species (shown schematically by the arrows) within the blocks.

[0095] In certain embodiments, with reference to [Fig.2D], an additional layer 11 can be formed on the tiles P1, P2, P3 placed on the intermediate substrate 2. Said additional layer can advantageously be formed by epitaxy on each tile.

[0096] Depending on the case, the substrate 20 illustrated in FIGS. 2B, 2C or 2D is used as a temporary substrate in the rest of the process for forming the composite structure. The embodiments of FIGS. 2C and 2D may optionally be combined. In this case, the additional layer is advantageously produced before the implantation of the atomic species, in order to prevent the thermal budget for growth of the additional layer from causing premature fracture of the blocks along the weakening zone.

[0097] Said temporary substrate is intended to be assembled to a receiving substrate, in order to transfer the paving stones or portions of paving stones thereto.

[0098] Figures 3A to 3H illustrate different steps of preparing the receiving substrate and transferring the tiles from the temporary substrate to the receiving substrate, in the case where the receiving substrate is a semiconductor-on-insulator type substrate.

[0099] With reference to [Fig.3A], the receiving substrate 3 successively comprises a base substrate 30, an electrically insulating layer 31, for example of silicon oxide (also called buried oxide layer) and a layer 32 of the second material.

[0100] With reference to [Fig.3B], a mask 4 is formed on the layer 32 having openings at the location of the cavities to be formed.

[0101] With reference to [Fig.3C], the second material exposed by the openings of the mask 4 is etched, preferably over the entire thickness of the layer 32, to form cavities C1, C2, C3. The electrically insulating layer 31 in fact forms a barrier layer of engraving.

[0102] With reference to [Fig.3D], the mask 4 is removed so as to free the surface of the remaining layer 32. The substrate thus obtained can be used as a receiving substrate to receive the tiles.

[0103] In an optional embodiment, before assembling the receiving substrate and the temporary substrate, an electrically insulating layer 33 can be formed on the walls of the cavities. Thus, the walls and the bottom of the cavities are covered with the electrically insulating material, which makes it possible to electrically insulate the blocks which will be transferred into the cavities from the portions of the layer 32 which extend between the cavities and from the base substrate 30.

[0104] With reference to [Fig.3F], the receiving substrate 3 and the temporary substrate 20 are assembled, by placing the blocks P1, P2, P2 and the corresponding cavities C1, C2, C3 opposite each other (in this figure, it is the substrate of [Fig.3D] which has been shown, but the substrate of [Fig.3E] could alternatively be used).

[0105] As illustrated in [Fig.3G], the adhesion of the substrates 3 and 20 is done via the paving stones and the bottom of the cavities.

[0106] With reference to [Fig.3H], the intermediate substrate is removed. In the illustrated embodiment, the blocks have a weakening zone 11. Consequently, the removal of the intermediate substrate and the rest of the blocks is carried out by detachment along the weakening zone 11. Only the portions of blocks P' 1, P'2, P'3 are thus transferred onto the receiving substrate.

[0107] In other embodiments (not shown), the removal of the intermediate substrate can be achieved by grinding the substrate from the face opposite the receiving substrate, until reaching the main surface of the substrate 3.

[0108] Figures 4A to 4F illustrate different steps of preparing the receiving substrate and transferring the tiles from the temporary substrate to the receiving substrate, in the case where the receiving substrate is a solid substrate.

[0109] With reference to [Fig.4A], the receiving substrate 3 is a solid substrate of the second material.

[0110] With reference to [Fig.4B], a mask 4 is formed on the substrate 3 having openings at the location of the cavities to be formed.

[0111] With reference to [Fig.4C], the second material exposed by the openings of the mask 4 is etched to form cavities C1, C2, C3. The etching time is adjusted according to the desired depth for the cavities.

[0112] Then, the mask 4 is removed so as to free the surface of the substrate 3. The substrate thus obtained can be used as a receiving substrate to receive the tiles.

[0113] In an optional embodiment, illustrated in [Fig.4D], prior to assembly of the receiving substrate and the temporary substrate, an electrically conductive layer may be formed insulating layer 33 on the surface of the substrate 3 so as to cover the walls and the bottom of the cavities. Said layer 33 makes it possible to electrically insulate the blocks which will be transferred into the cavities from the rest of the substrate 3.

[0114] With reference to [Fig.4E], the receiving substrate 3 and the temporary substrate 20 are assembled, by placing the blocks P1, P2, P2 and the corresponding cavities C1, C2, C3 opposite each other (in this figure, it is the substrate of [Fig.4D] which has been shown, but the electrically insulating layer 33 could possibly be omitted).

[0115] The adhesion of the substrates 3 and 20 is done via the paving stones and the bottom of the cavities.

[0116] With reference to [Fig.4F], the intermediate substrate is removed. In the illustrated embodiment, the blocks have a weakening zone 11. Consequently, the removal of the intermediate substrate and the rest of the blocks is carried out by detachment along the weakening zone 11. Only the block portions P' 1, P'2, P'3 are thus transferred to the receiving substrate.

[0117] In other embodiments (not shown), the removal of the intermediate substrate can be achieved by grinding the substrate from the face opposite the receiving substrate, until reaching the main surface of the substrate 3.

[0118] Figures 5A to 5F illustrate different steps of preparation of the receiving substrate and transferring the tiles from the temporary substrate to the receiving substrate, in the case where the receiving substrate comprises a substrate of the second material covered with an electrically insulating layer.

[0119] With reference to [Fig.5A], the receiving substrate 3 comprises a solid substrate 30 of the second material covered with an electrically insulating layer 34.

[0120] With reference to [Fig.5B], a mask 4 is formed on the layer 34 having openings at the location of the cavities to be formed.

[0121] With reference to [Fig.5C], the electrically insulating material exposed by the openings of the mask 4 is etched, preferably over the entire thickness of the layer 34, to form cavities C1, C2, C3. The substrate 30 in fact forms an etching stop layer.

[0122] With reference to [Fig.5D], the mask 4 is removed so as to free the surface of the layer 34. The substrate thus obtained can be used as a receiving substrate to receive the tiles.

[0123] With reference to [Fig.5E], the receiving substrate 3 and the temporary substrate 20 are assembled, by placing the blocks P1, P2, P2 and the corresponding cavities C1, C2, C3 opposite each other.

[0124] The adhesion of the substrates 3 and 20 is done via the paving stones and the bottom of the cavities.

[0125] With reference to [Fig.5F], the intermediate substrate is removed. In the mode of rea illustrated, the paving stones have a weakening zone 11. Consequently, the removal of the intermediate substrate and the rest of the paving stones is carried out by detachment along the weakening zone 11. Only the portions of paving stones P' 1, P'2, P'3 are thus transferred onto the receiving substrate.

[0126] In other embodiments (not shown), the removal of the intermediate substrate can be achieved by grinding the substrate from the face opposite the receiving substrate, until reaching the main surface of the substrate 3.

Claims

Claims

1. A method of manufacturing a composite structure comprising at least two blocks on a substrate, comprising: (a) forming a temporary substrate (20) comprising an intermediate substrate (2) and a plurality of blocks (PI, P2, P3) of a first material arranged on the intermediate substrate (2), (b) assembling the temporary substrate (20) with a receiving substrate (3) made of a second material different from the first material via said blocks (PI, P2, P3), and (c) removing the intermediate substrate (2) so as to transfer at least a portion (P' 1, P'2, P'3) of the blocks onto the receiving substrate (3) to form the composite structure, said method being characterized in that: the receiving substrate (3) comprises a main surface from which cavities (C1, C2, C3) extend, the receiving substrate (3) being assembled to the temporary substrate (20) on the side of said main surface so that each block (PI, P2,P3) is received in a respective cavity (Cl, C2, C3) and in that, after removal of the intermediate substrate (2), the free surface of the paving stone portions (P' 1, P'2, P'3) is substantially aligned with the main surface of the receiving substrate (3), and the formation of said temporary substrate (20) comprises removing each paving stone (PI, P2, P3) from at least one donor substrate (1) of the first material and placing each paving stone (PI, P2, P3) on the intermediate substrate (2), each donor substrate (1) having a diameter smaller than the diameter of the intermediate substrate (2).,

2. The method of claim 1, wherein step (a) of forming the temporary substrate (20) comprises forming a weakening zone (10) of each tile (P1, P2, P3) delimiting a respective tile portion (P' 1, P'2, P'3) to be transferred, and step (c) of removing the intermediate substrate (2) comprises detaching each tile portion (P' 1, P'2, P'3) along said weakening zone (10).

3. The method of claim 2, wherein the formation of said weakening zone (10) comprises an implantation of atomic species within each block (PI, P2, P3).

4. A method according to one of claims 1 to 3, wherein the second material is a semiconductor material, such as silicon or silicon carbide, a piezoelectric material, or glass.

5. Method according to claim 4, in which the receiving substrate (3) is a semiconductor-on-insulator type substrate successively comprising a base substrate (30), an electrically insulating layer (31), and a layer (32) of the second material defining the main surface of the receiving substrate, and the cavities (Cl, C2, C3) are formed in the layer (32) of the second material up to the electrically insulating layer (31).

6. A method according to claim 4, wherein the cavities (C1, C2, C3) are formed in a surface region of the receiving substrate (3) made of the second material.

7. Method according to one of claims 5 or 6, in which at least a part of the walls of at least one of said cavities (C1, C2, C3) is covered with an electrically insulating film (33), so as to electrically insulate the respective portion of block (P' 1, P'2, P'3) from the receiving substrate (3).

8. A method according to claim 4, wherein the receiving substrate (3) comprises at least one surface layer of the second material covered with an electrically insulating layer (34) and the cavities (Cl, C2, C3) are formed in said electrically insulating layer (34).

9. Method according to one of claims 1 to 8, in which the assembly of the temporary substrate (20) on the receiving substrate (3) is carried out by molecular adhesion.

10. Method according to one of claims 1 to 9, in which each block (P1, P2, P3) has a thickness of between 20 pm and 1000 pm, preferably between 100 pm and 700 pm, and the portion (P' 1, P'2, P'3) transferred from each block has a thickness of between 30 nm and 1.5 pm.

11. Method according to claim 10, in which each cavity (Cl, C2, C3) has a depth of between 30 nm and 1.5 pm.

12. Method according to one of claims 1 to 11, in which, at the end of step (c) of removing the intermediate substrate (2), the free surface of the paving portions (P'1, P'2, P'3) is in relief relative to the main surface of the receiving substrate (3), the method further comprising a step of polishing said surfaces.

13. Method according to one of claims 1 to 12, in which the first material is chosen from: - a semiconductor material, such as a III-V material, in particular indium nitride (InN), gallium nitride (GaN), aluminum nitride (AIN), indium arsenide (InAs), gallium arsenide (GaAs), aluminum arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP) or aluminum phosphide (AlP), or a IV or IV-IV material, including germanium or silicon carbide (SiC), - a piezoelectric material, such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), potassium sodium niobate (KxNabx NbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a compound of lead magnesium niobate and titanate lead (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN), and / or - an electrically insulating material, such as diamond, strontium titanate, yttria zirconia or sapphire.

14. Method according to one of claims 1 to 13, comprising, before step (b) of assembling the temporary substrate (20) and the receiving substrate (3), the formation by epitaxy of at least one additional layer (11) of a third material on each tile.

15. Method according to one of claims 1 to 14, in which the cavities (Cl, C2, C3) are formed by chemical etching through a mask (4) having openings at the location of said cavities.

16. Method according to one of claims 1 to 15, in which each cavity (Cl, C2, C3) is sized to receive a single block, said cavity having a shape identical to that of said block.

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