A process for producing what are known as two pseudo-donor substrates, each comprising at least two wafer tiles on a carrier substrate.

Abstract

The present invention relates to a process for manufacturing what are known as two pseudo donor substrates, each comprising at least two wafer tiles mounted on a carrier substrate, comprising: arranging at least two tiles on a first carrier substrate to form a first pseudo donor substrate comprising at least two tiles, each tile having an initial thickness of 300 μm or more; bonding the first pseudo donor substrate to a second carrier substrate via the tiles; and separating the tiles into two portions of a first thickness and a second thickness, maintaining the first portion of the tile with the first thickness on the first pseudo donor substrate and transferring the second portion of the tile with the second thickness to the second carrier substrate to form a second pseudo donor substrate, wherein the second thickness is comprised between 20% and 80% of the initial thickness of the tile of the first pseudo donor substrate.

Description

[Technical Field]

[0001] The present invention relates to a process for producing what are known as two pseudo donor substrates, each comprising at least two wafer tiles on a carrier substrate.

[0002] In the fields of microelectronics, optics, or optoelectronics, the design of multilayer structures sometimes requires a layer of a donor substrate to be transferred to a carrier or receiving substrate.

[0003] One well-known layer transfer process is the Smart Cut™ process, in which a donor substrate is implanted with atomic species to form weakened zones that delimit the layer to be transferred, the donor substrate is bonded to a carrier substrate, and the donor substrate is cut along the weakened zones to transfer the layer from the donor substrate to the carrier substrate. However, that process assumes that the donor substrate and the carrier substrate are the same size.

[0004] However, while silicon substrates are available in relatively large sizes, typically 300 mm in diameter, other materials of interest currently exist only in the form of bulk substrates of smaller sizes, e.g., 10 or 15 cm in diameter. This is particularly true for III-V semiconductor materials, including nitrides (e.g., related to binary compounds such as indium nitride (InN), gallium nitride (GaN), and aluminum nitride (AlN)), arsenides (e.g., related to binary compounds such as indium arsenide (InAs), gallium arsenide (GaAs), and aluminum arsenide (AlAs)), and phosphides (e.g., related to binary compounds such as indium phosphide (InP), gallium phosphide (GaP), and aluminum phosphide (AlP)).

[0005] Rather than transferring the entire layer of the donor substrate, a solution based on the Smart-Cut™ process consists in removing one or more tiles from at least one donor substrate, transferring the tiles to a first carrier substrate to form what is known as a pseudo-donor substrate, creating a weakened zone in each tile by implanting atomic species, bonding the pseudo-donor substrate to a second carrier substrate via the tiles, and cutting each tile along the weakened zone to transfer a portion of each tile to the second carrier substrate, where the first and second substrates are the same size.

[0006] 1 shows a plan view and a cross-sectional view of a carrier substrate S on which a number of tiles P1-P9 from at least one donor substrate are arranged. In this example, there are nine tiles distributed in three rows and three columns.

[0007] The structure can be fabricated using a "pick and place" technique in which a donor substrate is cut into tiles, and then each tile is placed onto the surface of a carrier substrate with the assistance of a robot.

[0008] However, because each tile is transferred individually to the first substrate, and because the precision required to align the tiles is particularly demanding, this technique can be very slow. Furthermore, the aforementioned materials of interest can be particularly expensive, and it is therefore desirable to minimize the waste that may be created during transfer.

[0009] Here, the thickness of the tile placed on the carrier substrate is equal to the thickness of the donor substrate, i.e., on the order of several hundred micrometers (for example, between 200 μm and 700 μm). During the Smart-Cut™ process, portions of the tile are transferred. The thickness of the transferred portions, on the order of micrometers, is limited by the depth to which the atomic species are implanted. The pseudo-donor substrate can then be reused using various surface treatment processes so that it can be reused in further Smart-Cut™-type processes. These processes, aimed at adapting the surface finish of the tile obtained by the Smart-Cut™ process for further bonding to a new carrier substrate, consume 2 μm to 3 μm of the tile's thickness. This cycle, including a surface treatment process followed by the Smart-Cut™ process, can be repeated several times.

[0010] However, each cycle slightly degrades the pseudo donor substrate, causing defects associated with successive implants to accumulate and reducing the uniformity of the tile thickness of the pseudo donor substrate. In practice, the number of times a pseudo donor substrate can be used is less than the theoretical number of tile portions that can be successively formed to the tile thickness. As a result, over the course of all cycles, only tile thicknesses of less than about 100 micrometers are used.

[0011] The solution of cutting the donor substrate through its thickness before cutting the tiles from it is not satisfactory for most materials. As an example, indium phosphide (InP), available in the form of a substrate with a diameter of 100 mm and a thickness of 625 μm, is a very brittle material. Therefore, cutting such a material in such a way as to form two substrates of smaller thickness, and subsequent handling of the substrates, is difficult to achieve on an industrial scale. Summary of the Invention

[0012] One object of the present invention is to devise a process for the manufacture of pseudo donor substrates comprising tiles disposed on a carrier substrate that is faster than the "pick and place" process, and which further makes it possible for pseudo donor substrates manufactured by this process to generate significantly less waste of the material from which the tiles are formed compared to pseudo donor substrates obtained directly by the "pick and place" method when the pseudo donor substrates are used in a maximum number of consecutive SmartCut™ processes.

[0013] To this end, the invention provides a process for producing what are known as two pseudo donor substrates, each comprising at least two wafer tiles on a carrier substrate, the process comprising the following successive steps: disposing at least two tiles on a first carrier substrate to form a first pseudo donor substrate comprising at least two tiles, each tile having an initial thickness of 100 μm or greater; bonding a first pseudo donor substrate to a second carrier substrate via a tile; Separating the tile into two portions of a first thickness and a second thickness, maintaining the first portion of the tile with the first thickness on a first pseudo donor substrate, and transferring the second portion of the tile with the second thickness to a second carrier substrate to form a second pseudo donor substrate, wherein the second thickness is comprised between 20% and 80% of the initial thickness of the tile on the first pseudo donor substrate; The present invention relates to a process including the steps of:

[0014] The process according to the present invention allows for the formation of at least two pseudo donor substrates comprising tiles disposed on a carrier substrate and for only one "pick and place" type tile placement process to be performed.

[0015] Thanks to the present invention, after use of the quasi-donor substrate in a maximum number of consecutive Smart-Cut™ processes, the substrate results in a waste substrate with tiles of a smaller thickness than the waste substrate obtained from a quasi-donor substrate manufactured in a simple "pick and place" process and used in the same number of consecutive Smart-Cut™ processes.

[0016] In certain embodiments, the process further includes cutting at least two tiles from the donor substrate across the entire thickness of the donor substrate, such that the at least two tiles have a thickness equal to the thickness of the donor substrate from which the at least two tiles were cut.

[0017] In this case, the donor substrate advantageously has a diameter smaller than the diameter of the first and second carrier substrates.

[0018] In certain embodiments, the tiles are separated by mechanical cutting using a blade or by laser cutting.

[0019] In certain embodiments, the process includes, prior to placing at least two tiles on the first carrier substrate: bonding the first donor substrate to a second donor substrate of the same diameter as the first donor substrate using an attachment layer to form a thick donor substrate; cutting at least two tiles from the thick donor substrate such that the initial thickness of each of the tiles is equal to the thickness of the thick substrate; Includes:

[0020] In this case, the first donor substrate and the second donor substrate advantageously have a diameter smaller than the diameter of the first carrier substrate and the second carrier substrate.

[0021] Advantageously, the separation of the at least two tiles involves selective attack of the bonding layer.

[0022] Separation of the tiles by selectively attacking the bonding layer may be performed using a laser, using mechanical cutting with a blade, and / or using chemical-mechanical cutting.

[0023] In certain embodiments, at least two tiles are sequentially placed on the first carrier substrate using a robot.

[0024] It is particularly advantageous for the first carrier substrate to have the same diameter as the second carrier substrate.

[0025] In certain embodiments, the first carrier substrate comprises the same material as the second carrier substrate.

[0026] It is particularly advantageous that the first carrier substrate and / or the second carrier substrate may comprise silicon, glass, sapphire, and / or polycrystalline silicon carbide.

[0027] In some embodiments, each tile: semiconductor materials, for example 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 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), lead magnesium niobate and lead titanate (PMN-PT) compounds, zinc oxide (ZnO), aluminum nitride (AlN) or aluminum scandium nitride (AlScN), and / or an electrically insulating material, such as diamond, strontium titanate, yttria-stabilized zirconia, or sapphire; Includes:

[0028] In some embodiments, the process comprises: bonding the first and second pseudo donor substrates to a third carrier substrate via the tiles of the first and second pseudo donor substrates, respectively; separating the tile into two portions of a third thickness and a fourth thickness, maintaining the first portion of the tile with the third thickness on each of the first and second pseudo donor substrates, and transferring the second portion of the tile with the fourth thickness to a third carrier substrate to form a third pseudo donor substrate; Further includes:

[0029] Advantageously, the fourth thickness of the second portion of the tile is comprised between 20% and 80% of each of the first and second thicknesses.

[0030] The tile is separated into two portions of a third thickness and a fourth thickness by mechanical cutting using a blade, or by laser cutting, or by any other method known to those skilled in the art.

[0031] Another subject of the invention is a process for transferring tiles from a substrate called a pseudo-donor substrate to a receiving substrate, comprising: forming a pseudo donor substrate according to the process described above; forming a weakened zone by implanting atomic species into each tile of the pseudo donor substrate to define the portion to be transferred; bonding a pseudo-donor substrate to a receiving substrate; transferring portions of the tiles from the pseudo-donor substrate to a receiving substrate by severing each tile along the weakened zone; The process includes:

[0032] It is particularly advantageous for the portion of each tile that is transferred from the pseudo-donor substrate to have a thickness comprised between 30 nm and 1.5 μm.

[0033] Advantageously, the receiving substrate comprises silicon, glass, sapphire, SiC, and / or AlN. [Brief explanation of the drawings]

[0034] Other features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. [Figure 1] 1A and 1B are plan and cross-sectional views of a carrier substrate with multiple tiles from a donor substrate disposed thereon. [Figure 2] FIG. 2A illustrates one embodiment of a process for manufacturing a pseudo donor substrate according to the present invention, in which, in order, tiles are cut from a donor substrate ( FIG. 2A ), the tiles are placed on a first carrier substrate to form a first pseudo donor substrate ( FIG. 2B ), the first pseudo donor substrate is bonded to a second carrier substrate via the tiles of the first pseudo donor substrate ( FIG. 2C ), and the tiles are separated into two portions of a first thickness and a second thickness to form a second pseudo donor substrate ( FIG. 2D ), the first pseudo donor substrate is bonded to a third carrier substrate via the tiles of the first pseudo donor substrate ( FIG. 2E ), and the tiles are separated into two portions of a third thickness and a fourth thickness to form a third pseudo donor substrate ( FIG. 2F ). [Figure 3]FIG. 3A illustrates another embodiment of a process according to the present invention, in which, in sequence, a first donor substrate is bonded to a second donor substrate via a bonding layer to form a thick donor substrate ( FIG. 3A ), tiles are cut from the thick donor substrate ( FIG. 3B ), the tiles are bonded to a first carrier substrate via the tiles of the first pseudo donor substrate to form a first pseudo donor substrate ( FIG. 3C ), the first pseudo donor substrate is bonded to a second carrier substrate via the tiles of the first pseudo donor substrate ( FIG. 3D ), and the tiles are separated into two portions of a first thickness and a second thickness to form a second pseudo donor substrate ( FIG. 3E ), the first pseudo donor substrate is bonded to a third carrier substrate via the tiles of the first pseudo donor substrate ( FIG. 3F ), ​​and the tiles are separated into two portions of a third thickness and a fourth thickness to form a third pseudo donor substrate ( FIG. 3G ). [Figure 4] 4A-4C illustrate a process using a pseudo donor substrate, which process includes, in order, forming a weakened zone in one tile of the pseudo donor substrate by atomic implantation to separate the portion of the tile to be transferred (FIG. 4A), bonding the pseudo donor substrate to a receiving substrate via the implanted tile (FIG. 4B), and cutting the pseudo donor substrate along the weakened zone to transfer the portion of the tile separated by the weakened zone (FIG. 4C). Detailed Description of the Embodiments

[0035] For ease of reading, the drawings may not be drawn to scale.

[0036] The present invention relates to a process for producing at least two substrates called pseudo-donor substrates.

[0037] In this description, what is meant by pseudo donor substrate is a substrate comprising tiles arranged on a carrier substrate, which can be used to transfer a thin layer of active material from which the tiles are made to a receiving substrate, for example using a SmartCut™ type process.

[0038] The use of such pseudo-donor substrates is particularly beneficial when the active material is not available in the form of a large sized substrate.

[0039] In a process according to the present invention, a first pseudo donor substrate is produced by arranging at least two tiles on a carrier substrate. Other pseudo donor substrates are produced from this first pseudo donor substrate by bonding the first pseudo donor substrate to other carrier substrates via the tiles and by separating the tiles from the first donor substrate in a manner that transfers portions of the tiles to each of the other carrier substrates. This advantageously makes it possible to eliminate an additional tile-arrangement step.

[0040] Two embodiments of a process for manufacturing a pseudo donor substrate according to the present invention are described in more detail below. As the present invention extends to a process for transferring an active layer using one of these pseudo donor substrates, one embodiment of such a transfer process will be further described.

[0041] First embodiment of the manufacture of a pseudo-donor substrate 2A-2F schematically show a first particular embodiment of a process according to the invention, comprising the steps of arranging tiles P1, P2, P3 on a first carrier substrate 3 to form a first pseudo donor substrate 1, transferring first portions of the tiles P1, P2, P3 from the first pseudo donor substrate 1 to a second carrier substrate 4 to form a second pseudo donor substrate 2, and finally transferring second portions of the tiles to a third carrier substrate 6 to form a third pseudo donor substrate 7.

[0042] According to this first embodiment, tiles P1-P3 are cut from a donor substrate 5, as shown in Figure 2A. The tiles P1-P3 may be cut using any technique known to a person skilled in the art. The cutting may in particular be performed by sawing and / or cleaving, and / or by laser cutting. The cutting may for example further be combined with a step of partial plasma etching of the cutting lines, a technique also known as "plasma dicing".

[0043] The tiles P1-P3 are preferably cut from the donor substrate 5 through the entire thickness of the donor substrate 5, so that each tile P1-P3 has a thickness equal to the thickness of the donor substrate 5 from which the tile was cut.

[0044] Advantageously, tiles P1-P3 are made from commercially unavailable materials in the form of large-sized donor substrates. Thus, donor substrate 5 may have a diameter of less than 30 cm, for example, on the order of 10 or 15 cm. This is particularly true for III-V semiconductor materials, including nitrides (e.g., related to binary compounds such as indium nitride (InN), gallium nitride (GaN), and aluminum nitride (AlN)), arsenides (e.g., related to binary compounds such as indium arsenide (InAs), gallium arsenide (GaAs), and aluminum arsenide (AlAs)), and phosphides (e.g., related to binary compounds such as indium phosphide (InP), gallium phosphide (GaP), and aluminum phosphide (AlP)). This also applies to IV or IV-IV semiconductor compounds, such as germanium and silicon carbide.

[0045] The tiles P1 to P3 may also be made of a piezoelectric material, such as lithium tantalate (LiTaO3), or alternatively lithium niobate (LiNbO3), potassium sodium niobate (K x Na 1-x The ceramic may be made from lead zirconate titanate (PZT), lead magnesium niobate and lead titanate compounds (PMN-PT), zinc oxide (ZnO), aluminum nitride (AlN), or aluminum scandium nitride (AlScN) (a non-limiting list).

[0046] The tiles P1 to P3 may also be made from an electrically insulating material, such as diamond, strontium titanate (SrTiO3), yttria stabilized zirconia (YSZ), or even sapphire.

[0047] Each tile P1 to P3 has a minimum initial thickness of 100 μm, preferably an initial thickness comprised between 300 μm and 600 μm, more preferably between 400 μm and 600 μm, and even more advantageously this initial thickness being equal to the thickness of the donor substrate 5.

[0048] FIG. 2B shows an arrangement of tiles P1-P3 on a first carrier substrate 3 to form a first pseudo donor substrate 1 comprising tiles P1-P3 and a first carrier substrate 3. In FIG.

[0049] Beneficially, the first carrier substrate 3 has a larger diameter than the donor substrate 5. For example, the first carrier substrate 3 may comprise any material available in larger substrate sizes than the donor material, such as silicon, glass, polycrystalline SiC, sapphire (Al2O3), or any other semiconductor material available in larger diameters (e.g., diameters of 200 mm or greater). Given the size difference between the donor substrate 5 and the first carrier substrate 3, some donor substrates 5 may require tiles to be placed over the entire surface of the first carrier substrate 3, depending on the desired tile placement density.

[0050] The placement of each tile P1-P3 may be performed using a "pick and place" technique, in which a robot grabs an already cut tile from the donor substrate 5 and places the tile in a predetermined position on the first carrier substrate 3. Thus, the tiles P1-P3 are placed on the first carrier substrate 3 in sequence.

[0051] In a particular embodiment, each tile P1-P3 is adhered to the first carrier substrate 3 by molecular adhesion. To this end, surface treatments of the tiles P1-P3 and / or the first carrier substrate 3 may be carried out beforehand to promote proper molecular adhesion. These treatments may include, inter alia, cleaning, deposition of a bonding layer such as silicon oxide (SiO2), plasma activation, and annealing prior to bonding.

[0052] In other embodiments, the bonding of the tiles P1-P3 to the first carrier substrate 3 may involve an intermediate bonding layer, for example a polymeric, eutectic or ceramic bonding layer.

[0053] FIG. 2C shows the bonding of the first pseudo donor substrate of FIG. 2B to a second carrier substrate 5 via tiles P1-P3.

[0054] In the same manner as for the first carrier substrate 3, the second carrier substrate 4 advantageously has a diameter larger than the diameter of the donor substrate 5. For example, the second carrier substrate 4 comprises any material that is available in larger substrate sizes than the donor substrate material, such as silicon, glass, polycrystalline SiC, Al2O3, or any other semiconductor material that is available in larger diameters and that allows the bonding step to be performed.

[0055] In one particular embodiment of bonding the first pseudo donor substrate 1 of FIG. 2B to the second carrier substrate 4, the second carrier substrate 4 has the same diameter as the first carrier substrate 3, for example, around 300 mm, and / or the second carrier substrate 4 comprises the same material as the first carrier substrate 3.

[0056] It is particularly advantageous for each tile P1-P3 to be bonded to the second carrier substrate 3 by molecular adhesion. To this end, a surface treatment of the tiles P1-P3 and / or the second carrier substrate 4 may be carried out beforehand in order to promote a suitable molecular adhesion. Depending on the materials considered, these treatments may in particular comprise cleaning, deposition of a bonding layer such as silicon oxide (SiO2), plasma activation, and / or chemical-mechanical polishing (CMP) before bonding. Furthermore, in order to strengthen the adhesion, an annealing operation is generally carried out after bonding.

[0057] Next, referring to FIG. 2D , the tile is separated into two parts with a first thickness e1 and a second thickness e2 to maintain the first parts P'1 to P'3 of the tile with a first thickness e1 on the first pseudo donor substrate 1, and to transfer the second parts P"1 to P"3 of the tile with a second thickness e2 to a second carrier substrate 4 to form a second pseudo donor substrate 2.

[0058] The second thickness e2 is within 20% to 80% of the initial thickness of the tiles P1 to P3 of the first pseudo donor substrate 1, and therefore the second thickness e2 is preferably within 20 μm to 560 μm, and more preferably within 200 μm to 400 μm.

[0059] The tiles P1-P3 may be separated by mechanical cutting using a blade, by laser cutting, or by any other cutting technique compatible with the material to be cut. In any case, the tiles cannot be separated using the Smart-Cut™ process because the first and second thicknesses are much greater than the implantation depth accessible by industrially available implantation devices (which is on the order of 1 μm).

[0060] Thus, the process according to the present invention advantageously allows for the production of two pseudo donor substrates by performing only one "pick and place" step of placing tiles on a donor substrate, and because these "pick and place" steps are lengthy and cumbersome, the process according to the present invention is quicker than a process that involves producing each pseudo donor substrate by placing tiles on a carrier substrate.

[0061] Optionally, the process according to this embodiment may further include bonding the first pseudo donor substrate 1 (shown in FIG. 2E) to a third carrier substrate 6 via tiles P′1 to P′3 of the first pseudo donor substrate 1.

[0062] In the same manner as for the first carrier substrate 3 and the second carrier substrate 4, the third carrier substrate 6 beneficially has a diameter larger than the diameter of the donor substrate 5. For example, the third carrier substrate 3 comprises any material that is available in larger substrate sizes than the donor substrate material, such as, for example, silicon, glass, polycrystalline SiC, sapphire, or any other semiconductor material available in larger diameters.

[0063] According to one particular embodiment of the bonding of the third carrier substrate 6 to the first pseudo donor substrate 1, the third carrier substrate 6 has the same diameter as the first carrier substrate 3 and the second carrier substrate 4 and / or comprises the same material as the first carrier substrate 3 and the second carrier substrate 4.

[0064] It is particularly advantageous for each of the portions P'1-P'3 to be bonded to the third carrier substrate 6 by molecular adhesion. Because cutting can lead to a deterioration in the crystalline quality of the tiles and / or to a surface roughness that cannot be directly used for molecular bonding, prior surface treatments may be performed on the tiles P'1-P'3 and / or on the third carrier substrate 6 to promote proper molecular adhesion. These treatments may include, in particular, cleaning, deposition of a bonding layer such as silicon oxide (SiO), plasma activation, and / or polishing (CMP) prior to bonding. Those skilled in the art may select the most appropriate technique depending on the material of interest and / or the cutting technique. However, if the bonding technique does not require a particularly low level of roughness, for example, when a polymer adhesive is used, it is possible to omit any surface treatment. Furthermore, to strengthen the adhesion, an annealing operation is generally performed after bonding.

[0065] Referring to FIG. 2F, the method then further includes a step of separating the tiles P'1 to P'3 into two parts having a third thickness e3 and a fourth thickness e4, maintaining the first part of the tiles having the third thickness e3 on the first pseudo donor substrate 1, and transferring the second part of the tiles having the fourth thickness e4 to a third carrier substrate 6 to form a third pseudo donor substrate 7.

[0066] The fourth thickness of the second portion of the tile is between 20% and 80% of each of the first and second thicknesses, and is preferably between 40 μm and 300 μm, and more preferably between 100 μm and 250 μm.

[0067] In this case, the tiles P'1 to P3' are further separated into two parts of a third thickness e3 and a fourth thickness e4 by mechanical cutting using a saw blade, by laser cutting, or by any other cutting technique adapted to the material to be cut.

[0068] As an alternative to, or in addition to, bonding the first pseudo donor substrate 1 to the third carrier substrate 6 to form the third pseudo donor substrate 7, the second pseudo donor substrate 2 may be further bonded to a new carrier substrate to form a further pseudo donor substrate (not shown).

[0069] Thus, at this stage in the process according to the present invention, it is possible to form up to four pseudo donor substrates from a single donor substrate assembly and a single tile placement step, for example using the "pick and place" method used in forming the first pseudo donor substrate 1.

[0070] The number of pseudo donor substrates that can be formed from a first pseudo donor substrate depends on the initial thickness of the donor substrate and the precision of the cutting method.

[0071] The pseudo-donor substrate thus formed can be used to transfer portions of tiles of fine thickness onto a carrier substrate using the SmartCut™ process.

[0072] The process of forming a pseudo donor substrate may be repeated until a pseudo donor substrate with a tile thickness comprised between 50 μm and 200 μm is obtained, depending on the thickness that can be picked up by the SmartCut™ process and the number of times the pseudo donor substrate can be reused.

[0073] Second embodiment of the fabrication of a pseudo-donor substrate 3A-3G schematically show a second embodiment of a process according to the present invention, which comprises the steps of placing tiles P11, P12, P13 on a first carrier substrate 13 to form a first pseudo donor substrate 11, and then transferring portions of tiles P11, P12, P13 from the first pseudo donor substrate 11 to a second carrier substrate 14 to form a second pseudo donor substrate 12.

[0074] According to this second embodiment of the present invention, a first donor substrate 18 is bonded to a second donor substrate 19 having the same diameter as the first donor substrate 18 via a bonding layer 20 to form a thick donor substrate 15 (shown in FIG. 3A).

[0075] The first donor substrate 18 and the second donor substrate 19 are advantageously made from materials that are not commercially available in the form of large-sized donor substrates. Thus, the first donor substrate 18 and the second donor substrate 19 may have diameters of less than 30 cm, for example, on the order of 10 or 15 cm. This is particularly true for III-V semiconductor materials, including nitrides (e.g., related to binary compounds such as indium nitride (InN), gallium nitride (GaN), and aluminum nitride (AlN)), arsenides (e.g., related to binary compounds such as indium arsenide (InAs), gallium arsenide (GaAs), and aluminum arsenide (AlAs)), and phosphides (e.g., related to binary compounds such as indium phosphide (InP), gallium phosphide (GaP), and aluminum phosphide (AlP)). This is also true for IV or IV-IV semiconductor compounds, such as germanium and silicon carbide.

[0076] The first donor substrate 18 and the second donor substrate 19 may further comprise a piezoelectric material, such as lithium tantalate (LiTaO), or alternatively lithium niobate (LiNbO), potassium sodium niobate (K x Na 1-xThe ceramic may be made from lead, magnesium, zinc, zinc oxide, aluminum nitride (AlN), or aluminum scandium nitride (AlScN) (a non-limiting list).

[0077] The first donor substrate 18 and the second donor substrate 19 may also be made from an electrically insulating material, such as, for example, diamond, strontium titanate (SrTiO 3 ), yttria stabilized zirconia (YSZ), or even sapphire.

[0078] First donor substrate 18 and second donor substrate 19 may be made from the same material or from different materials.

[0079] Depending on the material and diameter of the first and second donor substrates, the thickness of the substrates is generally comprised between 120 μm and 700 μm.

[0080] The bonding layer 20 may be an oxide layer (oxide / oxide bonding is easy to implement on an industrial scale), a polymer bonding layer, a eutectic bonding layer, or even a ceramic bonding layer, with the bonding layer material being chosen for its ability to withstand the subsequent cutting step and for its ability to be selectively removed relative to the materials of the first and second donor substrates.

[0081] Referring to FIG. 3B, tiles P11-P13 are cut from thick donor substrate 15 such that the initial thickness of each of tiles P11-P13 is equal to the thickness of thick substrate 15.

[0082] Each of the tiles P11 to P13 has an initial thickness of 400 μm to 1400 μm, preferably 400 μm to 700 μm.

[0083] The tiles P11 to P13 can be cut using any technique known to those skilled in the art. Cutting may in particular be performed by sawing and / or cleaving, and also by laser cutting. Cutting may for example further be combined with a step of partial plasma etching of the cutting lines, a technique also known as "plasma dicing".

[0084] Referring to FIG. 3C, tiles P11-P13 are then placed on first carrier substrate 13 to form first pseudo donor substrate 11 comprising first carrier substrate 13 and tiles P11-P13.

[0085] In the same manner as in the first embodiment, the placement of each tile P11 to P13 may be performed by a robot using "pick and place" techniques, so that the tiles P11 to P13 are placed on the first carrier substrate 13 in order.

[0086] Each tile P11-P13 may be bonded to the first carrier substrate 13 by molecular adhesion, possibly after surface treatment of the tiles P11-P13 and / or the first carrier substrate 13 (cleaning, deposition of a bonding layer such as silicon oxide (SiO2), plasma activation and annealing before bonding) or by an intermediate bonding layer (polymer bonding layer, eutectic bonding layer or ceramic bonding layer).

[0087] 3D, the first pseudo donor substrate 11 is then bonded, for example by molecular adhesion, to the second carrier substrate 14 via the tiles P11-P13. In the same manner as in the first embodiment, surface treatment of the tiles P11-P13 and / or the second carrier substrate 14 (cleaning, deposition of a bonding layer such as silicon oxide (SiO2), plasma activation, polishing, etc.) may be performed beforehand to promote proper molecular adhesion.

[0088] Further in the same manner as in the first embodiment, the first carrier substrate 13 and the second carrier substrate 14 may beneficially have a diameter larger than the diameter of the donor substrate 15. For example, the first carrier substrate 13 and the second carrier substrate 14 may comprise any material available in larger substrate sizes than the donor substrate material, such as silicon, glass, polycrystalline SiC, Al2O3, or any other semiconductor material available in larger diameters. The second carrier substrate 14 may optionally have the same diameter as the first carrier substrate 13, e.g., around 300 mm, and / or the second carrier substrate 14 may comprise the same material as the first carrier substrate 13.

[0089] Next, the tiles P11 to P13 are separated into two parts with a first thickness and a second thickness so that a first part of the tiles P11 to P13 with a first thickness is maintained on the first pseudo donor substrate 11 and a second part of the tiles with a second thickness is transferred to a second carrier substrate 14 to form a second pseudo donor substrate 12.

[0090] Thus, in this embodiment, the process also advantageously allows two pseudo donor substrates to be manufactured by performing only one long and tedious step of placing tiles on a carrier substrate, for example, using a "pick and place" method. Thus, the process according to the present invention is quicker than a process that involves systematically using a "pick and place" method to form each pseudo donor substrate.

[0091] 3E, according to this second embodiment, separation of the tiles P11-P13 preferably involves selectively attacking the bonding layer 20. Separation of the tiles by selectively attacking the bonding layer 20 may be performed using a laser, using mechanical cutting with a blade, and / or using chemical-mechanical cutting. In any case, the tiles cannot be separated using the Smart-Cut™ process, since the first and second thicknesses are much greater than the implantation depth accessible by industrially available implantation devices (which is on the order of 1 μm).

[0092] After the tiles have been separated, any bonding layer residues are removed to expose the free surfaces of the tiles, and if necessary, finishing processes such as chemical mechanical polishing and / or planarization are carried out to achieve a tile surface finish suitable for subsequent use of the tiles.

[0093] According to this embodiment, furthermore, the process according to the invention comprises: bonding the first and second pseudo donor substrates 11, 12 to a third carrier substrate 16 via the tiles P'11 to P'13 of the first and second pseudo donor substrates 11, 12, respectively (shown in FIG. 3F for the first pseudo donor substrate 11, not shown for the second pseudo donor substrate 12); Separating the tiles P'11 to P'13 into two parts with a third thickness e13 and a fourth thickness e14, and maintaining the first parts of the tiles with the third thickness on the first pseudo donor substrate 11 and the second pseudo donor substrate 12, respectively (as shown in FIG. 3G in the case of the second pseudo donor substrate 12), and transferring the second parts of the tiles with the fourth thickness to a third carrier substrate 16 to form a third pseudo donor substrate 17; It may further include.

[0094] This variation of the process according to the present invention advantageously allows for the production of up to four pseudo donor substrates by performing the step of placing tiles on a carrier substrate to form a first pseudo donor substrate only once.

[0095] According to another variation of the process, the first pseudo donor substrate, the second pseudo donor substrate, and the third pseudo donor substrate may be further bonded to another carrier substrate to produce further pseudo donor substrates.

[0096] Depending on the preference, all pseudo donor substrates obtained by the pseudo donor substrate manufacturing process according to the invention have a tile thickness comprised between 50 μm and 300 μm.

[0097] Process for transferring tiles from a pseudo-donor substrate to a receiver substrate The present invention extends to a process for transferring tiles from a pseudo-donor substrate to a receiving substrate.

[0098] The process for transferring the tiles includes forming a pseudo donor substrate according to any one of the embodiments of the pseudo donor substrate manufacturing process described above. By way of example, the pseudo donor substrate may be a first pseudo donor substrate 1 obtained after forming a second pseudo donor substrate 2 (shown in FIG. 2D ) or a third pseudo donor substrate 7 (shown in FIG. 2F ). By way of further example, the pseudo donor substrate may be the second pseudo donor substrate 2 (shown in FIG. 2D ) or the third pseudo donor substrate 7 (shown in FIG. 2F ).

[0099] Alternatively, the pseudo donor substrate may be the first pseudo donor substrate 11 after the formation of the second pseudo donor substrate 12 (shown in FIG. 3E) or the formation of the third pseudo donor substrate 17 (shown in FIG. 3G). The pseudo donor substrate may be the pseudo donor substrate 12 (shown in FIG. 3E) or the third pseudo donor substrate 17 (shown in FIG. 3G).

[0100] As a further alternative, the pseudo donor substrate may be the first pseudo donor substrate 1, the second pseudo donor substrate 2, or the third pseudo donor substrate 7, or may be the first pseudo donor substrate 11, the second pseudo donor substrate 12, or the third pseudo donor substrate 17 after being used to form a further pseudo donor substrate (not shown), or may be a further pseudo donor substrate as described above (also not shown).

[0101] Depending on the preference, the tiles of the pseudo donor substrate of the tile transfer process according to the invention have a thickness comprised between 50 μm and 300 μm.

[0102] By way of example, an embodiment of a sequence of operations in a tile transfer process is shown in FIGS. 4A-4C, starting from the first pseudo donor substrate 1 after the formation of the second pseudo donor substrate 2.

[0103] Referring to Figure 4A, the tile transfer process according to the present invention comprises the formation of weakened zones 101 in each tile (tiles P'1 to P'3 in the case of Figure 4A) of an already manufactured pseudo donor substrate (pseudo donor substrate 1 in the case of Figure 4A) in order to demarcate the surface layers of tiles C1, C2, C3, which surface layers are intended to be transferred to a receiving substrate 102.

[0104] As indicated diagrammatically by the arrows, the weakened zones 101 are advantageously formed by implantation of atomic species, such as hydrogen and / or helium, in the tiles at a depth corresponding to the thickness of the layers C1, C2, C3 to be transferred.

[0105] The pseudo donor substrate is then bonded via the tile to a receiving substrate 102 as shown in Figure 4A.

[0106] The receiving substrate 102 has the same diameter as the pseudo donor substrate, e.g., on the order of 300 mm. The receiving substrate 102 comprises silicon, glass, sapphire, SiC, AlN, and / or any other semiconductor material of interest, with a substrate size larger than the substrate size of the initial donor substrate.

[0107] In order to be able to bond the tiles together to the receiving substrate, they need to have the same thickness, and for this purpose, before bonding, it may be necessary to carry out a polishing (grinding) step to give the tiles a uniform thickness, and then a smoothing step to make the tile surface suitable for bonding.

[0108] It is particularly advantageous for each tile to adhere to the receiving substrate 102 by molecular adhesion. To this end, a surface treatment of the tiles and / or the second carrier substrate may be carried out beforehand to promote proper molecular adhesion.

[0109] Referring to FIG. 4C, the tiles are then cut along the weakened zones 101 to transfer the layers C1, C2, C3 delimited by the weakened zones 101 to a receiving substrate 102.

[0110] The transferred layers C1, C2, C3 typically have a thickness of 30 nm to 1.5 μm.

[0111] It is beneficial for one and the same pseudo donor substrate to be reused multiple times in the steps of forming the weakened zone, bonding, and cutting along the weakened zone, so that with each repetition of the steps, a new portion of the tile of the pseudo donor substrate is transferred to a new receiving substrate 102.

[0112] Between each transfer, the tile surface formed by cleavage along the weakened zones 101 is treated to achieve a roughness and surface finish that allows for good bonding to a new receiving substrate 102. By way of example, such treatments may include chemical-mechanical polishing, fine grinding, chemical etching, plasma treatment, deposition of a smoothing layer, and / or heat treatment, depending on the tile material. Performing such surface treatments may consume tile thickness on the order of 0.5 μm to 5 μm, depending on the treatment considered.

[0113] Depending on the preference, several layer transfer cycles can be performed sequentially using the same pseudo donor substrate, with each cycle including the steps of forming a weakened zone, bonding, cutting along the weakened zone, and surface treatment. Therefore, one and the same pseudo donor substrate can be reused 1 to 30 times, with each cycle consuming a total tile thickness of 1 to 6 μm. Therefore, reusing one and the same pseudo donor substrate in multiple cycles allows for greater consumption of the potentially rare and expensive material that makes up the tile, thus reducing material waste. However, since each cycle further degrades the pseudo donor substrate (lack of uniformity, uncorrected deformation to the crystalline structure, degradation to the tile edges, and breakage of the pseudo donor substrate), the pseudo donor substrate can only be reused a limited number of times. In practice, if less than 50% of the tile's surface area can be bonded, the pseudo donor substrate is considered no longer usable.

[0114] Thus, the pseudo donor substrate fabrication process according to the present invention advantageously allows for the formation of pseudo donor substrates with initial tile thicknesses that are smaller than donor substrates made from the same materials.

[0115] As an example, a process for producing pseudo donor substrates from substrates made of indium phosphide (InP) 625 μm thick and 100 mm in diameter allows for the production of pseudo donor substrates exhibiting InP tiles with a minimum thickness of 100 μm, such that after 15 cycles, 75 μm of the tile thickness has been consumed (at a rate of 5 μm per cycle), and the resulting wasted thickness is only 15 μm, rather than the 550 μm that would be the case if tiles with an initial thickness of 625 μm were used for the same number of cycles.

Claims

1. A process for manufacturing what are known as two pseudo donor substrates (1, 2), each comprising at least two wafer tiles on a carrier substrate, said process comprising the following successive steps: - arranging at least two tiles (P1, P2) on a first carrier substrate (3) to form a first pseudo donor substrate (1) comprising said at least two tiles, each tile having an initial thickness of 100 μm or more; bonding said first pseudo donor substrate (1) to a second carrier substrate (4) via said tiles (P1, P2); separating the tile into two portions (P'1, P'2, P"1, P"2) of a first thickness (e1) and a second thickness (e2), maintaining the first portions (P'1, P'2) of the tile with the first thickness (e1) on the first pseudo donor substrate, and transferring the second portions (P"1, P"2) of the tile with the second thickness (e2) to the second carrier substrate (4) to form a second pseudo donor substrate (2), the second thickness (e2) is comprised between 20% and 80% of the initial thickness of the tile of the first pseudo donor substrate.

2. 2. The process of claim 1, further comprising the step of cutting the at least two tiles from the donor substrate (5) across the entire thickness of the donor substrate such that the at least two tiles have a thickness equal to the thickness of the donor substrate from which the at least two tiles (P1, P2) were cut.

3. 3. The process of claim 2, wherein the donor substrate (5) has a diameter smaller than the diameters of the first carrier substrate (3) and the second carrier substrate (4).

4. A process according to any one of claims 1 to 3, wherein the tiles (P1, P2) are separated by mechanical cutting using a blade or by laser cutting.

5. Before placing the at least two tiles (P1, P2) on the first carrier substrate (3), bonding the first donor substrate (18) to a second donor substrate (19) of the same diameter as the first donor substrate using a bonding layer (20) to form a thick donor substrate (15); cutting the at least two tiles (P1, P2) from the thick donor substrate (15) such that the initial thickness of each of the tiles is equal to the thickness of the thick substrate; The process of claim 1 , comprising:

6. 6. The process of claim 5, wherein the first donor substrate (18) and the second donor substrate (19) have a diameter smaller than the diameter of the first carrier substrate (3) and the second carrier substrate (4).

7. 7. A process according to claim 5 or 6, wherein the step of separating the at least two tiles (P1, P2) involves selectively attacking the bonding layer (20).

8. 8. The process of claim 7, wherein the step of separating the tiles by selectively attacking the bonding layer is performed using a laser, using blade-assisted mechanical cutting, and / or by chemical treatment.

9. The process of any one of claims 1 to 8, wherein the at least two tiles are sequentially placed on the first carrier substrate using a robot.

10. The process of any one of claims 1 to 9, wherein the first carrier substrate has the same diameter as the second carrier substrate.

11. The process of any one of claims 1 to 10, wherein the first carrier substrate comprises the same material as the second carrier substrate.

12. The process according to any one of the preceding claims, wherein the first carrier substrate and / or the second carrier substrate comprises silicon, glass, sapphire and / or polycrystalline SiC.

13. Each of the tiles (P1, P2) semiconductor materials, for example 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 IV or IV-IV materials, in particular germanium or silicon carbide (SiC); Piezoelectric materials, such as lithium tantalate (LiTaO ３ ), lithium niobate (LiNbO ３ ), potassium sodium niobate (K ｘ Na １－ｘ NbO ３ or KNN), barium titanate (BaTiO ３ ), quartz, lead zirconate titanate (PZT), lead magnesium niobate and lead titanate compound (PMN-PT), zinc oxide (ZnO), aluminum nitride (AlN), or aluminum scandium nitride (AlScN), and / or an electrically insulating material, such as diamond, strontium titanate, yttria-stabilized zirconia, or sapphire; The process according to any one of claims 1 to 12, comprising:

14. bonding the first and second pseudo donor substrates (1) and (2) to a third carrier substrate (6) via the tiles (P'1, P'2, P''1, P''2) of the first and second pseudo donor substrates, respectively; Separating the tile into two parts with a third thickness (e3) and a fourth thickness (e4), maintaining the first part of the tile with the third thickness (e3) on the first pseudo donor substrate (1) and the second pseudo donor substrate (2), respectively, and transferring the second part of the tile with the fourth thickness (e4) to the third carrier substrate (6) to form a third pseudo donor substrate (7); The process of any one of claims 1 to 13, further comprising:

15. 15. The process according to claim 14, wherein the fourth thickness (e4) of the second portion of the tile is comprised between 20% and 80% of each of the first thickness (e1) and the second thickness (e2).

16. 16. A process according to claim 14 or 15, wherein the tile is separated into the two parts of the third thickness (e3) and the fourth thickness (e4) by mechanical cutting using a blade or by laser cutting.

17. A process for transferring tiles from a substrate called a pseudo-donor substrate to a receiving substrate, said process comprising: forming a pseudo donor substrate (1) according to any one of claims 1 to 16; - implanting atomic species into each tile (P1, P2) of said pseudo donor substrate to form weakened zones (101) to define portions (C1, C2) to be transferred; bonding said pseudo donor substrate (1) to a receiving substrate (102); transferring portions (C1, C2) of the tiles from the pseudo donor substrate (1) to the receiving substrate (102) by severing each tile (P1, P2) along the weakened zone (101); A process including:

18. A process according to claim 17, wherein the portions (C1, C2) of each tile transferred from the pseudo donor substrate have a thickness comprised between 30 nm and 1.5 μm.

19. The process of claim 17 or 18, wherein the receiving substrate (102) comprises silicon, glass, sapphire, SiC, or AlN.

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