A method for manufacturing two so-called pseudo-donor substrates, each comprising at least two blocks on a supporting substrate.

Abstract

The invention relates to a method for manufacturing two substrates called pseudo-donor substrates (1, 2), each comprising at least two blocks on a support substrate. The method comprises the following successive steps: - placing at least two blocks (P1, P2) on a first support substrate (3), each block having an initial thickness greater than or equal to 300 µm, so as to form a first pseudo-donor substrate (1) comprising the at least two blocks; - bonding said first pseudo-donor substrate (1) to a second support substrate (4) via the blocks (P1, P2); - separating the blocks into two portions (P'1, P'2, P''1, P''2) of a first (e1) and a second (e2) thickness, so as to retain a first portion (P'1, P'2) of said blocks having the first thickness (e1) on the first pseudo-donor substrate and transferring a second portion (P''1,P''2) of the paving stones having the second thickness (e2) on the second supporting substrate (4) to form a second pseudo-donor substrate (2), the second thickness (e2) being between 20% and 80% of the initial thickness of the paving stones of the first pseudo-donor substrate. Figure for the abbreviation: Fig 2D,

Description

Title of the invention: Method for manufacturing two so-called pseudo-donor substrates, each comprising at least two blocks on a support substrate. Technical field

[0001] The invention relates to a method for manufacturing two substrates, called donor pseudosubstrates, each comprising at least two blocks on a support substrate. PRIOR TECHNOLOGY

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

[0003] A well-known layer transfer method is the Smart Cut™ process, in which a weakened zone delimiting the layer to be transferred is formed by implanting atomic species in the donor substrate. The donor substrate is then bonded to the support substrate, and the donor substrate is detached along the weakened zone to transfer the layer from the donor substrate to the support substrate. However, this process assumes that the donor substrate and the support substrate are of identical size.

[0004] However, while silicon substrates are available with a relatively large size, typically a diameter of 300 mm, other materials of interest currently exist only in the form of smaller, massive substrates, for example 10 or 15 cm in diameter. This is particularly the case for III-V semiconductor materials, including nitrides (for example, in the case of binary compounds, indium nitride (InN), gallium nitride (GaN) and aluminium nitride (AIN)), arsenides (for example, in the case of binary compounds, indium arsenide (InAs), gallium arsenide (GaAs) and aluminium arsenide (AlAs)), and phosphides (for example, in the case of binary compounds, indium phosphide (InP), gallium phosphide (GaP) and aluminium phosphide (A1P)).

[0005] Instead of transferring an entire layer of the donor substrate, a solution based on the Smart Cut™ process consists of taking one or more blocks from at least one donor substrate and transferring said blocks onto a first support substrate to form a so-called pseudo-donor substrate, creating a weakened zone in each block by implanting atomic species, bonding the pseudo-donor substrate to a second support substrate via the blocks, and detaching each block along the weakened zone so as to transfer a portion of each block onto the second support substrate. The first and second substrates present identical size.

[0006] Figure 1 shows a top view and a cross-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, arranged in three rows and three columns.

[0007] The manufacture of said structure can be carried out by the technique known as "Pick and Place", in which said donor substrate is cut into blocks and then each block is placed on the surface of the support substrate using a robot.

[0008] However, since each paving stone is individually transferred to the first substrate, this technique can be very slow, especially given the demanding precision required for paving stone alignment. Furthermore, the aforementioned materials of interest are sometimes particularly expensive, making it desirable to minimize any waste generated during the transfer process.

[0009] However, the thickness of the paving stones placed on the substrate is equal to the thickness of the donor substrate, i.e., on the order of a few hundred micrometers (for example, a thickness between 200 µm and 700 µm). During the Smart Cut™ process, a portion of these paving stones is transferred. The thickness of the transferred portion, on the order of a micrometer, is limited by the implantation depth of the atomic species. It is then possible to recycle the pseudo-donor substrate, through various surface treatment operations, in order to reuse it in a new Smart Cut™ process. Such operations, aimed at making the surface condition of the paving stones produced by the Smart Cut™ process compatible with new bonding to a new substrate, consume between 2 µm and 3 µm of the paving stone thickness. Such a cycle, including surface treatment operations followed by the Smart Cut™ process, can also be repeated several times.

[0010] However, each cycle degrades the donor pseudo-substrate a little more: defects related to successive implantations accumulate, and the thickness uniformity of the paving stones in the donor pseudo-substrate decreases. In practice, the number of uses of the donor pseudo-substrate is less than the theoretical number of paving stone segments that could be formed successively within the thickness of the paving stones. As a result, over all the cycles, less than one hundred micrometers of paving stone thickness are used.

[0011] The solution of cutting the donor substrate lengthwise prior to cutting the paving stones from said donor substrate is not satisfactory for most materials. For example, indium phosphide (InP), available as a substrate 100 mm in diameter and 625 µm thick, is a very brittle material. Cutting such a material to form two thinner substrates and the subsequent handling of said substrates are therefore difficult to produce industrially. BRIEF DESCRIPTION OF THE INVENTION

[0012] An object of the invention is to design a method for manufacturing donor pseudo-substrates comprising pavers deposited on a support substrate which is faster than the "pick and place" method, the donor pseudo-substrates manufactured by said method also allowing, when used in a maximum number of successive Smart Cut™ processes, to generate less waste of the materials constituting the pavers than the donor pseudo-substrates produced directly from said "pick and place" method.

[0013] To this end, the invention proposes a method for manufacturing two so-called pseudo-donor substrates, each comprising at least two tiles on a support substrate, the method comprising the following successive steps: - the placement, on a first supporting substrate, of at least two paving stones, each paving stone having an initial thickness greater than or equal to 100 pm, so as to form a first pseudo-donor substrate comprising the at least two paving stones, - the bonding of said first pseudo-donor substrate onto a second supporting substrate by means of the paving stones, - the separation of the paving stones into two portions of a first and a second thickness so as to keep a first portion of said paving stones having the first thickness on the first pseudo-donor substrate and to transfer a second portion of the paving stones having the second thickness on the second support substrate to form a second pseudo-donor substrate, the second thickness being between 20% and 80% of the initial thickness of the paving stones of the first pseudo-donor substrate.

[0014] The process according to the invention makes it possible to form at least two donor pseudo-substrates comprising pavers arranged on a support substrate by implementing the "pick and place" type paving process only once.

[0015] Thanks to the invention, following the use of said donor pseudo-substrates in a maximum number of successive Smart Cut™ processes, they lead to a waste substrate comprising pavers whose thickness is less than the waste substrate which would be obtained from a donor pseudo-substrate manufactured in a simple "pick and place" process and used in the same number of successive Smart Cut™ processes.

[0016] In some embodiments, the process further includes cutting at least two paving stones from a donor substrate, over the entire thickness of said donor substrate, so that the at least two paving stones have a thickness equal to the thickness of the donor substrate from which they were cut.

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

[0018] In some embodiments, the separation of the paving stones is achieved by cutting mechanical cutting using a blade or by laser cutting.

[0019] In certain embodiments, the method comprises, prior to placing the at least two paving stones on the first supporting substrate: - the bonding of a first donor substrate onto a second donor substrate of the same diameter as the first donor substrate by means of a bonding layer, so as to form a thick donor substrate, - cutting at least two blocks from the thick donor substrate, such that the initial thickness of each of said blocks is equal to the thickness of the thick substrate.

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

[0021] The separation of the at least two blocks advantageously includes a selective attack on the adhesive layer.

[0022] The separation of the paving stones by selective attack of the adhesive layer can be implemented by laser, by mechanical cutting assisted by a blade, and / or assisted by chemical treatment.

[0023] In some embodiments, the at least two tiles are placed successively on the first support substrate using a robot.

[0024] In a particularly advantageous way, the first support substrate has the same diameter as the second support substrate.

[0025] In some embodiments, the first support substrate comprises the same material as the second support substrate.

[0026] Particularly advantageously, the first support substrate and / or the second support substrate may comprise silicon, glass, sapphire and / or polycrystalline silicon carbide.

[0027] In certain embodiments, each block comprises: - a semiconductor material, such as a III-V material, in particular indium nitride (InN), gallium nitride (GaN), aluminium nitride (Ain), indium arsenide (InA), gallium arsenide (GaAs), aluminium arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP) or aluminium phosphide (A1P), or a IV or IV-IV material, in particular germanium or silicon carbide (SiC), - a piezoelectric material, such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), potassium-sodium niobate (KxNa, xNbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a lead-magnesium niobate-lead titanate compound (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.

[0028] In certain embodiments, the method further comprises: - the bonding of the first donor pseudo-substrate, respectively of the second donor pseudo-substrate, onto a third supporting substrate, via the blocks of the first donor pseudo-substrate, respectively of the second donor pseudo-substrate, - the separation of the paving stones into two portions of a third and a fourth thickness so as to keep a first portion of said paving stones having the third thickness on the first donor pseudo-substrate, respectively on the second donor pseudo-substrate, and to transfer a second portion of the paving stones having the fourth thickness onto the third support substrate to form a third donor pseudo-substrate.

[0029] The fourth thickness of the second portion of paving stones is advantageously between 20% and 80% of the first thickness, respectively of the second thickness.

[0030] The separation of the paving stones into two portions of the third and fourth thicknesses is carried out by mechanical cutting using a blade or by laser cutting or any other method known to the person skilled in the art.

[0031] Another object of the invention relates to a method for transferring paving stones from a so-called pseudo-donor substrate to a receiving substrate comprising: - the formation of a pseudo-donor substrate according to the process described above, - the formation of a weakened zone by implanting atomic species in each block of the donor pseudo-substrate to define a portion to be transferred - the bonding of the donor pseudo-substrate to a receiving substrate, - the transfer of a portion of the paving stones from the donor pseudo-substrate to the receiving substrate by detaching each paving stone along the weakening zone.

[0032] In a particularly advantageous way, the transferred portion of each block of the donor pseudo-substrate has a thickness between 30 nm and 1.5 pm.

[0033] The receiving substrate advantageously comprises silicon, glass, sapphire, SiC, and / or AlN. BRIEF DESCRIPTION OF THE FIGURES

[0034] Other features and advantages of the invention will become apparent from the detailed description that follows, with reference to the accompanying drawings, in which:

[0035] - Fig. 1 shows a top view and a cross-sectional view of a supporting substrate on which a plurality of paving stones from a donor substrate were placed,

[0036] - Figures 2A to 2F represent an embodiment of the manufacturing process of donor pseudo-substrates according to the invention, wherein the following steps are successively performed: cutting of blocks from a donor substrate ([Fig.2A]), placement of said blocks on a first support substrate so as to form a first donor pseudo-substrate ([Fig.2B]), bonding of said first donor pseudo-substrate with a second support substrate via the blocks of the first donor pseudo-substrate ([Fig.2C]), and separation of the blocks into two portions of a first and a second thickness so as to form a second donor pseudo-substrate ([Fig.2D]), bonding of the first donor pseudo-substrate onto a third support substrate via the blocks of the first donor pseudo-substrate ([Fig.2E]), and separation of the blocks into two portions of a third and fourth thickness so as to form a third donor pseudo-substrate ([Fig.2F]).

[0037] - Figures 3A to 3G represent another embodiment of the process according to the invention in which a first donor substrate is successively bonded to a second donor substrate by means of a bonding layer to form a thick donor substrate ([Fig.3A]), the cutting of blocks from the thick donor substrate ([Fig.3B]), the bonding of said blocks to a first support substrate by means of blocks from the first pseudo-donor substrate to form a first pseudo-donor substrate ([Fig.3C]), the bonding of said first pseudo-donor substrate to a second support substrate by means of blocks from the first pseudo-donor substrate ([Fig.3D]) and the separation of the blocks into two portions of a first and a second thickness to form a second pseudo-donor substrate ([Fig.3E]), the bonding of the first pseudo-donor substrate to a third support substrate by means of blocks from the first pseudo-donor substrate ([Fig.3F]) and the separation of the paving stones into two portions of a third and fourth thickness so as to form a third pseudo-donor substrate ([Fig.3G]), .

[0038] - Figures 4A to 4C represent a method of using said pseudo-substrates donors comprising successively the formation of a weakening zone in the tiles of one of said donor pseudo-substrates by atomic implantations so as to delimit a portion of the tiles to be transferred ([Fig.4A]), the bonding of the donor pseudo-substrate with a receiving substrate via the implanted tiles ([Fig.4B]) and the cutting of the donor pseudo-substrate along the weakening zone so as to transfer the portion of the tiles delimited by the weakening zone ([Fig.4C]).

[0039] For reasons of legibility, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0040] The invention relates to a method for manufacturing at least two substrates called pseudo-donor substrates.

[0041] In this description, a pseudo-donor substrate means a substrate comprising pavers placed on a support substrate, said pseudo-donor substrate being able to be used to transfer thin layers of the active material constituting the pavers onto a receiving substrate, for example by a Smart Cut™ type process.

[0042] The use of such a donor pseudo-substrate is of particular interest when the active material is not available in the form of large substrates.

[0043] In the process according to the invention, a first donor pseudo-substrate is made by placing at least two tiles on a support substrate. The other donor pseudo-substrates are made from this first donor pseudo-substrate by bonding the first donor pseudo-substrate to other support substrates via the tiles and separating the tiles from said first donor substrate so as to transfer a portion of it onto each of the other support substrates. This advantageously eliminates the need for additional tile placement steps.

[0044] Two embodiments of the manufacturing process for pseudo-donor substrates according to the invention are described in more detail below. Since the invention extends to an active layer transfer process using one of these pseudo-donor substrates, an embodiment of such a transfer process is further described.

[0045] First embodiment of manufacturing pseudo-donor substrates

[0046] Figures 2A to 2F schematically illustrate a first particular embodiment of the process according to the invention comprising the placement of the tiles PI, P2, P3 on a first support substrate 3 so as to form a first pseudo-donor substrate 1, the transfer of a first portion of the tiles PI, P2, P3 from the first pseudo-donor substrate 1 onto a second support substrate 4 so as to form a second pseudo-donor substrate 2, and finally the transfer of a second portion of said tiles onto a third support substrate 6 to form a third pseudo-donor substrate 7.

[0047] According to this first embodiment, blocks P1-P3 are cut from a donor substrate 5 as shown in [Fig. 2A]. The cutting of the blocks P1-P3 can be carried out by any technique known to those skilled in the art. In particular, it can be carried out by sawing and / or cleaving, or by laser cutting. It can also, for example, be combined with a step of partially etching the cutting lines by plasma, a technique known by the English term "plasma dicking".

[0048] The cutting of the paving stones P1-P3 in the donor substrate 5 is preferably carried out over the entire thickness of said donor substrate 5, so that each paving stone P1-P3 has a thickness equal to the thickness of the donor substrate 5 in which they were cut.

[0049] Advantageously, the P1-P3 paving stones are made from a material that is not commercially available as a large-dimension donor substrate. Thus, the donor substrate 5 may have a diameter of less than 30 cm, for example on the order of 10 or 15 cm. 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 aluminium nitride (AIN)), arsenides (for example for binary compounds, indium arsenide (InAs), gallium arsenide (GaAs) and aluminium arsenide (AlAs)), and phosphides (for example for binary compounds, indium phosphide (InP), gallium phosphide (GaP) and aluminium phosphide (A1P)). This is also the case for IV or IV-IV semiconductor compounds, such as germanium and silicon carbide.

[0050] The P1-P3 paving stones may also be made of a piezoelectric material, for example lithium tantalate (LiTaO3) or lithium niobate (LiNbO3), potassium-sodium niobate (KxNabxNbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a lead-magnesium niobate and lead titanate compound (PMN-PT), zinc oxide (ZnO), aluminium nitride (AIN) or aluminium and scandium nitride (AIScN) (non-limiting list).

[0051] The P1-P3 pavements can also be made of an electrically insulating material, such as, for example, diamond, strontium titanate (SrTiO3), yttria zirconia (YSZ), or sapphire.

[0052] Each paving stone P1-P3 has a minimum initial thickness of 100 pm, preferably an initial thickness between 300 pm and 600 pm, more preferably an initial thickness between 400 pm and 600 pm, this initial thickness being advantageously equal to the thickness of the donor substrate 5.

[0053] Fig. 2B illustrates the placement of the tiles P1-P3 on the first support substrate 3 to form a first pseudo-donor substrate 1 comprising the tiles P1-P3 and the first support substrate 3.

[0054] The first support substrate 3 advantageously has a diameter larger than the donor substrate 5. The first support substrate 3 includes, for example, any material available in a substrate size larger than the donor material, such as silicon, glass, polycrystalline SiC, sapphire (Al₂O₃), or any other semiconductor material available in a large diameter (i.e., a diameter greater than or equal to 200 or 300 mm). Given the size difference between the donor substrate 5 and the first support substrate 3, several donor substrates 5 may be required to tile the entire surface of the first support substrate 3 according to the desired paving density.

[0055] The placement of each paving stone P1-P3 can be implemented by the "Pick and Place" technique, whereby a robot picks up a paving stone previously cut from the donor substrate 5 and places it at a predetermined location on the first substrate support 3. The paving stones P1-P3 are therefore placed successively on the first substrate support 3.

[0056] In certain embodiments, each block P1-P3 adheres to the first support substrate 3 by molecular adhesion. To this end, surface treatments of the blocks P1-P3 and / or the first support substrate 3 may be carried out beforehand to promote good molecular adhesion. These treatments may include, in particular, cleaning, the deposition of an adhesive layer such as silicon dioxide (SiO2), plasma activation prior to bonding, and annealing.

[0057] In other embodiments, the bonding of the paving stones P1-P3 to the first substrate support 3 may involve an intermediate bonding layer, for example a polymer bonding layer, a eutectic bonding layer or a ceramic bonding layer.

[0058] Fig. 2C illustrates the bonding of the first donor pseudo-substrate of Fig. 2B onto a second support substrate 5 via the blocks P1-P3.

[0059] In the same way as the first support substrate 3, the second support substrate 4 advantageously has a diameter greater than the diameter of the donor substrate 5. The second support substrate 4 includes, for example, any material available in a substrate size greater than the material of the donor substrate such as silicon, glass, polycrystalline SiC, A12O3, or any other semiconductor material available in a large diameter and allowing the implementation of a bonding step.

[0060] In a particular embodiment of the bonding of the first pseudo-donor substrate 1 of [Fig.2B] onto the second support substrate 4, the second support substrate 4 has the same diameter as the first support substrate 3, for example on the order of 300 mm, and / or the second support substrate 4 comprises the same material as the first support substrate 3.

[0061] Advantageously, each P1-P3 block adheres to the second support substrate 3 by molecular adhesion. To this end, surface treatments of the P1-P3 blocks and / or the second support substrate 4 can be carried out beforehand to promote good molecular adhesion. Depending on the materials involved, these treatments may include, in particular, cleaning, the application of an adhesive layer such as silicon dioxide (SiO2), plasma activation before bonding, and / or chemical mechanical polishing (CMP). Furthermore, annealing is generally carried out after bonding to strengthen the adhesion.

[0062] Next, with reference to [Fig. 2D], the paving stones are separated into two portions of a first and a second thickness e1, e2 so as to keep a first portion P'1-P'3 of said paving stones having the first thickness e1 on the first donor pseudosubstrate 1 and to transfer a second portion P'1P'3 of the paving stones having the second thickness e2 on the second support substrate 4 to form a second donor pseudo-substrate 2.

[0063] The second thickness e2 is between 20% and 80% of the initial thickness of the paving stones P1-P3 of the first pseudo-donor substrate 1, so that the second thickness e2 is preferably between 20 pm and 560 pm, preferably still between 200 pm and 400 pm.

[0064] The separation of the P1-P3 pavers can be achieved by mechanical cutting using a blade, by laser cutting, or any other cutting technique compatible with the material to be cut. In any case, the separation of the pavers cannot be achieved using the Smart Cut™ process because the first and second thicknesses are much greater than the insertion depth accessible by industrially available setting machines (said depth being on the order of 1 µm).

[0065] Thus, the process according to the invention advantageously makes it possible to manufacture two donor pseudo-substrates by implementing a single step of placing the pavers on a donor substrate using the "pick and place" technique. Since these "pick and place" steps are long and tedious, the process according to the invention is faster than a process that would consist of manufacturing each donor pseudo-substrate by placing pavers on a support substrate.

[0066] Optionally, the process according to this embodiment may further include the bonding of the first donor pseudo-substrate 1 (represented in [Fig.2E]), onto a third support substrate 6, via the blocks P' l-P'3 of the first donor pseudo-substrate 1.

[0067] In the same way as the first support substrate 3 and the second support substrate 4, the third support substrate 6 advantageously has a diameter greater than the diameter of the donor substrate 5. The third support substrate 3 includes, for example, any material available in a substrate size greater than the material of the donor substrate such as silicon, glass, polycrystalline SiC, sapphire or any other semiconductor material available in a large diameter.

[0068] According to a particular embodiment of the bonding of the third support substrate 6 with the first donor pseudo-substrate 1, the third support substrate 6 has the same diameter as the first support substrate 3 and the second support substrate 4, and / or it comprises the same material as the first support substrate 3 and the second support substrate 4.

[0069] Advantageously, each portion P'l-P'3 adheres to the third support substrate 6 by molecular adhesion. Since cutting results in a degradation of the crystalline quality of the block and / or a rough surface that is not directly usable for molecular bonding, surface treatments of the blocks P'l-P'3 and / or the third support substrate 6 can be applied beforehand. To promote good molecular adhesion, these treatments may include cleaning, the application of an adhesive layer such as silicon dioxide (SiO2), plasma activation prior to bonding, and / or polishing (CMP). A person skilled in the art can choose the most suitable technique, particularly depending on the materials involved and / or the cutting technique. However, if the bonding technique does not require a particularly low surface roughness, for example, when a polymer adhesive is used, surface treatment may be unnecessary. Furthermore, annealing is generally performed after bonding to strengthen adhesion.

[0070] With reference to [Fig.2F], the process further comprises separating the paving stones P'1-P'3 into two portions of a third and a fourth thickness e3, e4 so as to keep a first portion of said paving stones having the third thickness e3 on the first donor pseudo-substrate 1 and to transfer a second portion of the paving stones having the fourth thickness e4 onto the third support substrate 6 to form a third donor pseudo-substrate 7.

[0071] The fourth thickness of the second portion of paving stones is between 20% and 80% of the first thickness, or the second thickness, respectively. The fourth thickness of the second portion of paving stones is preferably between 40 µm and 300 µm, and more preferably between 100 µm and 250 µm.

[0072] In this case also, the separation of the blocks P' l-P'3 into the two portions of the third and fourth thicknesses e3, e4 is carried out by mechanical cutting using a saw, by laser cutting or any other cutting technique compatible with the material to be cut.

[0073] Alternatively or additionally to the bonding of the first pseudo-donor substrate 1 with a third support substrate 6 so as to form a third pseudo-donor substrate 7, the second pseudo-donor substrate 2 can also be bonded to a new support substrate so as to form an additional pseudo-donor substrate (not shown).

[0074] Thus, at this stage of the process according to the invention, it is possible to form up to four pseudo-donor substrates from a single set of donor substrate and a single step of placing the tiles, for example by "pick and place", which was implemented on the occasion of the formation of the first pseudo-donor substrate 1.

[0075] The number of donor pseudo-substrates that can be formed from the first donor pseudo-substrate depends on the initial thickness of the donor substrate and the precision of the cutting process.

[0076] The pseudo-donor substrates thus formed can be used to transfer portions of thin paving stones onto a support substrate by the Smart Cut™ process.

[0077] The process of forming the donor pseudo-substrates can be repeated up to to reach pseudo-donor substrates with a paving thickness of between 50 pm and 200 pm, depending on the thickness that can be extracted by the Smart Cut™ process and the number of possible recyclings of the pseudo-donor substrate.

[0078] Second embodiment of manufacturing donor pseudo-substrates

[0079] Figures 3A to 3G schematically illustrate a second embodiment of the process according to the invention comprising placing Pli, P12, P13 blocks on a first support substrate 13 so as to form a first pseudo-donor substrate 11, then transferring a portion of the Pli, PI2, P13 blocks from said first pseudo-donor substrate 11 onto a second support substrate 14, to form a second pseudo-donor substrate 12.

[0080] According to this second embodiment of the invention, a first donor substrate 18 is bonded with a second donor substrate 19 of the same diameter as the first donor substrate 18 by means of a bonding layer 20, to form a thick donor substrate 15 (represented in [Fig.3A]).

[0081] Advantageously, the first donor substrate 18 and the second donor substrate 19 are made of a material that is not commercially available as a large-sized donor substrate. Thus, the first donor substrate 18 and the second donor substrate 19 may have a diameter of less than 30 cm, for example, on the order of 10 or 15 cm. This is particularly the case for III-V semiconductor materials, including nitrides (for example, in the case of binary compounds, indium nitride (InN), gallium nitride (GaN) and aluminium nitride (AIN)), arsenides (for example, in the case of binary compounds, indium arsenide (InAs), gallium arsenide (GaAs) and aluminium arsenide (AlAs)), and phosphides (for example, in the case of binary compounds, indium phosphide (InP), gallium phosphide (GaP) and aluminium phosphide (A1P)).This is also the case for IV or IV-IV semiconductor compounds, such as germanium and silicon carbide.

[0082] The first donor substrate 18 and second donor substrate 19 may also be made of a piezoelectric material, for example lithium tantalate (LiTaO3) or lithium niobate (LiNbO3), potassium-sodium niobate (KxNahxNbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a lead-magnesium niobate and lead titanate compound (PMN-PT), zinc oxide (ZnO), aluminium nitride (AIN) or aluminium-scandium nitride (AIScN) (non-limiting list).

[0083] The first donor substrate 18 and second donor substrate 19 can also be made of an electrically insulating material, such as, for example, diamond, strontium titanate (SrTiO3), yttria zirconia (YSZ), or sapphire.

[0084] The first donor substrate 18 and the second donor substrate 19 can be in the same material or a different material.

[0085] Depending on the material and diameter of the first and second donor substrates, the thickness of said substrates is generally between 120 pm and 700 pm.

[0086] The bonding layer 20 can be an oxide layer (an oxide / oxide bond being easy to implement industrially), a polymer bonding layer, a eutectic bonding layer or a ceramic bonding layer, the material of said bonding layer being chosen to be able to withstand the subsequent cutting step and to be able to be selectively removed from the material of the first and second donor substrate.

[0087] With reference to [Fig.3B], PI 1-P13 blocks are then cut from the thick donor substrate 15, so that the initial thickness of each of said blocks P11-P13 is equal to the thickness of the thick substrate 15.

[0088] Each PI 1-P13 block has an initial thickness of between 400 and 1400 pm, preferably between 400 pm and 700 pm.

[0089] The cutting of the PI 1-P13 paving stones can be carried out by any technique known to those skilled in the art. In particular, it can be carried out by sawing, or by laser cutting. It can also, for example, be combined with a step of partially engraving the cutting lines by plasma, a technique known by the English term "plasma dicking".

[0090] With reference to [Fig.3C], the PI 1-P13 blocks are then placed on the first support substrate 13 to form a first pseudo-donor substrate 11 comprising said first support substrate 13 and the P11-P13 blocks.

[0091] As in the first embodiment, the placement of each tile PI 1-P13 can be carried out using the "Pick and Place" technique with the aid of a robot. The tiles P11-P13 are thus placed successively on the first support substrate 13.

[0092] Each PI 1-P13 block can adhere to the first support substrate 13 by molecular adhesion following possible surface treatments of the P11-P13 blocks and / or the first support substrate 13 (cleaning, deposition of a bonding layer such as a silicon oxide (SiO2), plasma activation before bonding and annealing), or via an intermediate bonding layer (polymer bonding layer, eutectic bonding layer or ceramic bonding layer).

[0093] With reference to [Fig. 3D], the first donor pseudo-substrate 11 is then bonded to a second support substrate 14 via the blocks P11-P13, for example by molecular adhesion. As in the first embodiment, surface treatments of the blocks P11-P13 and / or the second support substrate 14 can be carried out beforehand to promote good molecular adhesion (cleaning, deposition of an adhesive layer such as silicon dioxide (SiO2), Plasma activation, polishing, etc.).

[0094] As in the first embodiment, the first support substrate 13 and the second support substrate 14 advantageously have a diameter greater than the diameter of the donor substrate 15. The first support substrate 13 and the second support substrate 14 comprise, for example, any material available in a substrate size larger than the donor substrate material, such as silicon, glass, polycrystalline SiC, Al2O3, or any other semiconductor material available in a large diameter. Optionally, the second support substrate 14 has the same diameter as the first support substrate 13, for example, on the order of 300 mm, and / or the second support substrate 14 comprises the same material as the first support substrate 13.

[0095] The PI 1-P13 blocks are then separated into two portions of a first and a second thickness so as to keep a first portion of said PI 1-P13 blocks presenting the first thickness on the first donor pseudo-substrate 11 and to transfer a second portion of the blocks presenting the second thickness onto the second support substrate 14 to form a second donor pseudo-substrate 12.

[0096] Thus, in this embodiment as well, the process advantageously allows the fabrication of two donor pseudo-substrates by implementing only once the lengthy and tedious step of placing the tiles on a support substrate, for example by the "pick and place" method. The process according to the invention is therefore faster than that which would consist of systematically implementing said "pick and place" method for the formation of each donor pseudo-substrate.

[0097] With reference to [Fig. 3E], according to this second embodiment, the separation of the PI 1-P 13 pavers preferably involves a selective attack on the adhesive layer 20. The separation of the pavers by selective attack on the adhesive layer 20 can be carried out by laser, by blade-assisted mechanical cutting, and / or by chemical treatment. In any case, the separation of the pavers cannot be carried out by the Smart Cut™ process because the first and second thicknesses are much greater than the implantation depth accessible by industrially available implanters (said depth being on the order of 1 µm).

[0098] After separating the paving stones, any remaining adhesive layer is removed to expose the free surface of the paving stones. If necessary, a finishing treatment, such as chemical polishing and / or planarization, is carried out to obtain a surface condition of the paving stones suitable for their subsequent use.

[0099] According to this embodiment as well, the method according to the invention may further comprise:

[0100] - the bonding of the first donor pseudo-substrate 11, respectively of the second pseudo-donor substrate 12, on a third support substrate 16 via paving stones P' 11-P' 13 of the first donor pseudo-substrate 11, respectively of the second donor pseudo-substrate 12 (represented on [Fig.3F] in the case of the first donor pseudo-substrate 11, not represented in the case of the second donor pseudo-substrate 12),

[0101] - the separation of the paving stones P' 11-P' 13 into two portions of a third and a fourth thickness el3, el4 so as to keep a first portion of said paving stones having the third thickness on the first donor pseudo-substrate 11, respectively on the second donor pseudo-substrate 12, and to transfer a second portion of the paving stones having the fourth thickness on the third support substrate 16 to form a third donor pseudo-substrate 17 (represented on [Fig.3G] in the case of the second donor pseudo-substrate 12).

[0102] This variant of the process according to the invention advantageously makes it possible to generate up to four donor pseudo-substrates by implementing only once the step of placing the tiles on a support substrate, so as to form a first donor pseudo-substrate.

[0103] According to other variants of the process, the first, second, third donor pseudosubstrates can still be glued onto other support substrates, so as to generate additional donor pseudosubstrates.

[0104] Preferably, all donor pseudo-substrates from the donor pseudo-substrate manufacturing process according to the invention have a paving thickness between 50 and 300 pm.

[0105] Method for transferring paving stones from a donor pseudo-substrate to a receiving substrate

[0106] The invention extends to a method for transferring paving stones from a donor pseudo-substrate to a receiving substrate.

[0107] The paving stone transfer process includes the formation of a donor pseudo-substrate according to any embodiment of the donor pseudo-substrate manufacturing process as previously described. By way of example, the donor pseudo-substrate may be the first donor pseudo-substrate 1 taken after the formation of the second donor pseudo-substrate 2 (as shown in [Fig. 2D]) or after the formation of the third donor pseudo-substrate 7 (as shown in [Fig. 2F]). By way of further example, the donor pseudo-substrate may be the second donor pseudo-substrate 2 (shown in [Fig. 2D]) or the third donor pseudo-substrate 7 (shown in [Fig. 2F]).

[0108] Alternatively, the donor pseudo-substrate may be the first donor pseudo-substrate 11 after the formation of the second donor pseudo-substrate 12 (as shown in [Fig. 3E]) or after the formation of the third donor pseudo-substrate 17 (as shown in [Fig. 3G]). The donor pseudo-substrate may also be the donor pseudo-substrate 12 (shown in [Fig. 3E]) or the third pseudo-substrate donor 17 (represented in [Fig.3G]).

[0109] Alternatively still, the donor pseudo-substrate may be the first, second, third donor pseudo-substrates 1, 2, 7 or the first, second, third donor pseudo-substrates 11, 12, 17 after their use for the formation of additional donor pseudo-substrates (not shown) or said additional donor pseudo-substrates (also not shown).

[0110] Preferably, the paving stones of the pseudo-substrate donor of the paving stone transfer process according to the invention have a thickness between 50 pm and 300 pm.

[0111] By way of example, the implementation of the continuation of the paving transfer process is shown in Figures 4A to 4C from the first donor pseudo-substrate 1 after the formation of the second donor pseudo-substrate 2.

[0112] With reference to [Fig.4A], the paving transfer process according to the invention includes the formation of a weakening zone 101 in each paving stone (on [Fig.4A], the paving stones P'1-P'3) of the previously manufactured donor pseudo-substrate (on [Fig.4A], the donor pseudo-substrate 1) in order to delimit a surface layer of said paving stones Cl, C2, C3 intended to be transferred onto a receiving substrate 102.

[0113] As shown schematically by the arrows, the embrittlement zone 101 is advantageously formed by implanting atomic species, such as hydrogen and / or helium, in the blocks, at a depth corresponding to the thickness of the Cl, C2, C3 layer to be transferred.

[0114] The donor pseudo-substrate is then glued to the receiving substrate 102, as illustrated in [Fig.4B], via the blocks.

[0115] The receiving substrate 102 has the same diameter as the pseudo-donor substrate, for example on the order of 300 mm. The receiving substrate 102 comprises silicon, glass, sapphire, SiC, AIN and / or any other semiconductor material of interest and has a larger substrate size than the initial donor substrate.

[0116] To allow for collective bonding of the paving stones to the receiving substrate, the paving stones must have the same thickness. To this end, it may be necessary to implement, before bonding, an abrasion process (or "grinding" in Anglo-Saxon terminology) to standardize the thickness of the paving stones, and then to implement a smoothing process to make the surface of the paving stones compatible with bonding.

[0117] Advantageously, each paving stone adheres to the receiving substrate 102 by molecular adhesion. To this end, surface treatments of the paving stones and / or the second supporting substrate can be applied beforehand to promote good molecular adhesion.

[0118] With reference to [Fig.4C], the paving stones are then detached along the weakening zone 101, in order to transfer the Cl, C2, C3 layers delimited by said weakening zone 101 onto the receiving substrate 102.

[0119] The transferred Cl, C2, C3 layers generally have a thickness between 30 nm and 1.5 pm.

[0120] Advantageously, the same donor pseudo-substrate is reused several times in the steps of forming a weakening zone, gluing and cutting along the weakening zone, so as to transfer at each implementation of said steps a new portion of the tiles of the donor pseudo-substrate onto a new receiving substrate 102.

[0121] Between each transfer, the surface of the paving stones formed during detachment along the weakened zone 101 is treated to achieve a roughness and surface finish that allows for good bonding to the new receiving substrate 102. By way of example, such a treatment may include, depending on the paving stone material: mechano-chemical polishing, fine-grain abrasion, chemical shrinkage, plasma treatment, the application of a smoothing layer, and / or heat treatment. The implementation of such a surface treatment may consume, depending on the treatment considered, a paving stone thickness of approximately 0.5 µm to 5 µm.

[0122] Preferably, several successive layer transfer cycles are implemented with the same donor pseudo-substrate, each cycle comprising the steps of forming a weakened zone, bonding, cutting along the weakened zone, and surface treatment. Thus, the same donor pseudo-substrate can be reused between one and thirty times, so that the sequence of said cycles consumes between 1 and 6 µm of paving stone thickness in total. Reusing the same donor pseudo-substrate in several cycles therefore makes it possible to consume a greater thickness of the potentially rare and expensive material constituting the paving stones, and thus to limit waste of said material.However, as each cycle degrades the donor pseudosubstrate a little more (non-uniformity defects, modification of the unhealed crystalline structure, degradation of the paving stone edges, breakage of the donor pseudosubstrate), the donor pseudosubstrate can only be reused a limited number of times. In practice, if less than 50% of the paving stone surface cannot be bonded, the donor pseudosubstrate is considered unusable.

[0123] Thus, the manufacturing process of pseudo-donor substrate according to the invention advantageously makes it possible to form pseudo-donor substrates having an initial paving thickness lower than the donor substrate from which they originate made of the same material.

[0124] By way of example, the process for manufacturing pseudo-donor substrates from an indium phosphide (InP) substrate 625 µm thick and 100 mm in diameter makes it possible to manufacture pseudo-donor substrates having InP blocks with a minimum thickness of 100 µm, so that after 15 cycles, a thickness of 75 µm (at a rate of 5 µm per cycle) of said blocks has been consumed and that no further material is needed. waste that a thickness of 15 pm instead of a thickness of 550 pm if paving stones with an initial thickness of 625 pm were used in the same number of cycles.

Claims

Demands

1. A method for manufacturing two so-called pseudo-donor substrates (1, 2), each comprising at least two blocks on a support substrate, the method comprising the following successive steps: - placing at least two blocks (P1, P2) on a first support substrate (3), each block having an initial thickness greater than or equal to 100 µm, so as to form a first pseudo-donor substrate (1) comprising the at least two blocks, - bonding said first pseudo-donor substrate (1) to a second support substrate (4) via the blocks (P1, P2), - separating the blocks into two portions (P'1, P'2, P'1, P'2) of a first (1e1) and a second (1e2) thickness so as to retain a first portion (P'1, P'2) of said blocks having the first thickness (1e1) on the first pseudo-donor substrate and to transfer a second portion (P'1, P'2) 1,P”2) paving stones having the second thickness (e2) on the second supporting substrate (4) to form a second donor pseudo-substrate (2), the second thickness (e2) being between 20% and 80% of the initial thickness of the paving stones of the first pseudo-donor substrate.

2. A method according to claim 1, further comprising cutting at least two pavers (PI, P2) from a donor substrate (5), over the entire thickness of said donor substrate, so that the at least two pavers have a thickness equal to the thickness of the donor substrate from which they were cut.

3. Method according to claim 2, wherein the donor substrate (5) has a diameter smaller than the diameters of the first support substrate (3) and the second support substrate (4).

4. A method according to any one of claims 1 to 3, wherein the separation of the blocks (PI, P2) is carried out by mechanical cutting using a blade or by laser cutting.

5. Method according to claim 1, comprising prior to the placement of at least two blocks (PI, P2) on the first support substrate (3): - the bonding of a first donor substrate (18) onto a second donor substrate (19) of the same diameter as the first donor substrate by means of a bonding layer (20), so as to form a thick donor substrate (15), - cutting at least two paving stones (PI, P2) from the thick donor substrate (15), so that the initial thickness of each of said paving stones is equal to the thickness of the thick substrate.

6. A method according to claim 5, wherein the first donor substrate (18) and the second donor substrate (19) have a diameter smaller than the diameters of the first support substrate (3) and the second support substrate (4).

7. A method according to any one of claims 5 or 6, wherein the separation of the at least two blocks (PI, P2) includes a selective attack of the bonding layer (20).

8. Method according to claim 7, wherein the separation of the paving stones by selective attack of the adhesive layer is carried out by laser, by mechanical cutting assisted by a blade, and / or assisted by chemical treatment.

9. A method according to any one of claims 1 to 8, wherein the at least two tiles are placed successively on the first support substrate using a robot.

10. A method according to any one of claims 1 to 9, wherein the first support substrate has the same diameter as the second support substrate.

11. A method according to any one of claims 1 to 10, wherein the first support substrate comprises the same material as the second support substrate.

12. A method according to any one of claims 1 to 11, wherein the first support substrate and / or the second support substrate comprises silicon, glass, sapphire and / or polycrystalline SiC.

13. A method according to any one of claims 1 to 12, wherein each block (PI, P2) comprises: - a semiconductor material, such as a III-V material, in particular indium nitride (InN), gallium nitride (GaN), aluminum nitride (AIN), indium arsenide (InA), gallium arsenide (GaAs), aluminum arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP), or aluminum phosphide (A1P), or a IV or IV-IV material, in particular germanium or silicon carbide (SiC), - a piezoelectric material, such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), potassium sodium niobate (KxNa,xNbO3 or KNN), barium titanate (BaTiO3), quartz, titano- lead zirconate (PZT), a lead-magnesium niobate and lead titanate (PMN-PT) compound, zinc oxide (ZnO), aluminium nitride (AIN) or aluminium scandium nitride (AIScN), and / or - an electrically insulating material, such as diamond, strontium titanate, yttria zirconia or sapphire.

14. A method according to any one of claims 1 to 13, further comprising: - the bonding of the first donor pseudo-substrate (1), respectively of the second donor pseudo-substrate (2), onto a third support substrate (6), by means of the blocks (P' 1, P'2, P” 1, P”2) of the first donor pseudo-substrate, respectively of the second donor pseudo-substrate, - the separation of the blocks into two portions of a third (e3) and a fourth (e4) thickness so as to keep a first portion of said blocks having the third thickness (e3) on the first donor pseudo-substrate (1), respectively on the second donor pseudo-substrate, and to transfer a second portion of the blocks having the fourth thickness (e4) onto the third support substrate (6) to form a third donor pseudo-substrate (7).

15. Method according to claim 14, wherein the fourth thickness (e4) of the second portion of paving stones is between 20% and 80% of the first thickness (e1), respectively of the second thickness (e2).

16. A method according to any one of claims 14 or 15, wherein the separation of the paving stones into the two portions of the third (e3) and fourth (e4) thicknesses is carried out by mechanical cutting using a blade or by laser cutting.

17. A method for transferring blocks from a so-called pseudo-donor substrate to a receiving substrate comprising: - the formation of a pseudo-donor substrate (1) according to any one of claims 1 to 16, - the formation of a weakening zone (101) by implanting atomic species in each block (PI, P2) of the pseudo-donor substrate to define a portion (Cl, C2) to be transferred, - the bonding of the pseudo-donor substrate (1) to a receiving substrate (102), - the transfer of a portion (Cl, C2) of the blocks of the pseudo-donor substrate (1) to the receiving substrate (102) by detaching each

18. paving (PI, P2) along the embrittlement zone (101). Method according to claim 17, wherein the portion (Cl, C2) transferred from each paving of the donor pseudo-substrate has a

19. thickness between 30 nm and 1.5 pm. Method according to any one of claims 17 or 18, wherein the receiving substrate (102) comprises silicon, glass, sapphire, SiC, or PAIN.

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