Method for manufacturing two substrates called donor pseudo-substrates each comprising at least two tiles on a carrier substrate
Patent Information
- Application Number
- EP2023841016
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-12-19
- Filing Date
- 2023-12-19
- Publication Date
- 2025-10-29
AI Technical Summary
The existing Smart Cut™ process for transferring layers from donor substrates to support substrates is inefficient and wasteful, especially when dealing with smaller, expensive III-V semiconductor materials, as it requires multiple cycles that degrade the substrates and result in significant material waste due to the need for precise alignment and handling of thin blocks.
A method to manufacture pseudo-donor substrates by placing blocks with initial thicknesses greater than 100 μm on a support substrate, bonding them to another substrate, and separating them into portions to form additional pseudo-donor substrates, allowing for multiple Smart Cut™ processes with reduced waste and faster processing compared to the traditional 'pick and place' method.
This method reduces material waste and increases efficiency by allowing multiple cycles of Smart Cut™ processes while maintaining substrate quality, enabling the use of smaller, expensive semiconductor materials with less degradation and improved handling.
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for manufacturing two substrates called pseudo-donor substrates, each comprising at least two blocks on a support substrate
[0002] TECHNICAL FIELD
[0003] The invention relates to a method for manufacturing two substrates called pseudo-donor substrates, each comprising at least two blocks on a support substrate.
[0004] STATE OF THE ART
[0005] In the field of microelectronics, optics or optoelectronics, the design of multilayer structures sometimes requires transferring a layer from a donor substrate to a support substrate or recipient substrate.
[0006] A well-known layer transfer method is the Smart Cut™ method, in which an embrittlement zone is formed by implantation of atomic species into the donor substrate, delimiting the layer to be transferred, the donor substrate is bonded to the support substrate, and the donor substrate is detached along the embrittlement zone to transfer the layer from the donor substrate to the support substrate. However, this method assumes that the donor substrate and the support substrate are of identical size.
[0007] However, while silicon substrates are available in relatively large sizes, typically 300 mm in diameter, other materials of interest currently only exist in the form of smaller bulk substrates, for example 10 or 15 cm in diameter. This is particularly the case for III-V semiconductor materials, including nitrides (e.g., for binary compounds, indium nitride (InN), gallium nitride (GaN) and aluminum nitride (AIN)), arsenides (e.g., for binary compounds, indium arsenide (InAs), gallium arsenide (GaAs) and aluminum arsenide (AlAs)), and phosphides (e.g., for binary compounds, indium phosphide (InP), gallium phosphide (GaP) and aluminum phosphide (AIP)).
[0008] Instead of transferring an entire layer of the donor substrate, a solution based on the Smart Cut™ process consists of removing one or more blocks from at least one donor substrate and transferring said blocks onto a first support substrate, to form a substrate called a pseudo-donor substrate, forming by implantation of atomic species a weakening zone in each block, bonding the pseudo-donor substrate onto a second support substrate via the blocks, and detaching each block along the weakening zone so as to transfer a portion of each block onto the second support substrate. The first and second substrates have an identical size. Figure 1 shows a top view and a sectional view of a support substrate S on which a plurality of blocks P1-P9 of at least one donor substrate have been arranged. In this example, there are nine blocks and they are distributed in three rows and three columns.
[0009] The manufacture of said structure can be carried out by the technique known as “Pick and Place” in English, 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.
[0010] However, since each paving stone is transferred individually onto the first substrate, this technique can be very slow, especially since the required precision in paving stone alignment is demanding. Furthermore, the materials of interest mentioned above are sometimes particularly expensive, so it is desirable to minimize any waste formed during the transfer.
[0011] However, the thickness of the blocks placed on the support substrate is equal to the thickness of the donor substrate, i.e. of 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 said blocks is transferred. The thickness of the transferred portion, of the order of a micrometer, is limited by the implantation depth of the atomic species. It is then possible to recycle the donor pseudo-substrate, by various surface treatment operations, in order to reuse it in a new Smart Cut™ type process. Such operations, aimed at making the state of the surfaces of the blocks resulting from the Smart Cut™ process compatible with a new bonding on a new support substrate, consume between 2 μm and 3 μm of block thickness. Such a cycle comprising the surface treatment operations followed by the Smart Cut™ process can also be repeated several times.
[0012] However, each cycle degrades the donor pseudo-substrate a little more: defects linked to successive implantations accumulate, the thickness uniformity of the blocks of the donor pseudo-substrate decreases. In practice, the number of uses of the donor pseudo-substrate is lower than the theoretical number of block portions that could be formed successively in the thickness of the blocks. As a result, over all the cycles, less than a hundred micrometers of block thickness are used.
[0013] The solution of cutting the donor substrate along the thickness direction prior to cutting the blocks in said donor substrate is not satisfactory for most materials. For example, indium phosphide (InP), available in the form of a 100 mm diameter and 625 μm thick substrate, is a very brittle material. Cutting such a material to form two substrates of smaller thickness and the subsequent handling of said substrates is therefore difficult to achieve industrially.
[0014] BRIEF DESCRIPTION OF THE INVENTION
[0015] An aim of the invention is to design a method for manufacturing donor pseudo-substrates comprising paving stones deposited on a support substrate which is faster than the “pick and place” method, the donor pseudo-substrates manufactured by said method also making it possible, when used in a maximum number of successive Smart Cut™ processes, to generate less waste of the materials constituting the paving stones than the donor pseudo-substrates resulting directly from said “pick and place” process.
[0016] To this end, the invention proposes a method for manufacturing two substrates called donor pseudosubstrates, each comprising at least two blocks on a support substrate, the method comprising the following successive steps:
[0017] - the placement, on a first support substrate, of at least two blocks, each block having an initial thickness greater than or equal to 100 μm, so as to form a first pseudo-donor substrate comprising the at least two blocks,
[0018] - bonding said first donor pseudo-substrate to a second support substrate by means of the blocks,
[0019] - separating the paving stones into two portions of a first and a second thickness so as to retain 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 onto 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.
[0020] The method according to the invention makes it possible to form at least two pseudo-donor substrates comprising paving stones arranged on a support substrate by only implementing the “pick and place” type paving method once.
[0021] By virtue of 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 blocks whose thickness is smaller 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. In certain embodiments, the method further comprises cutting the at least two blocks from a donor substrate, over the entire thickness of said donor substrate, such that the at least two blocks have a thickness equal to the thickness of the donor substrate from which they were cut.
[0022] In this case, the donor substrate advantageously has a diameter smaller than the diameters of the first support substrate and the second support substrate.
[0023] In some embodiments, the separation of the blocks is achieved by mechanical cutting using a blade or by laser cutting.
[0024] In some embodiments, the method comprises, prior to placing the at least two tiles on the first support substrate:
[0025] - bonding a first donor substrate to 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,
[0026] - cutting the at least two paving stones from the thick donor substrate, such that the initial thickness of each of said paving stones is equal to the thickness of the thick substrate.
[0027] In this case, the first donor substrate and the second donor substrate advantageously have a diameter smaller than the diameters of the first support substrate and the second support substrate.
[0028] The separation of the at least two blocks advantageously includes a selective attack of the bonding layer.
[0029] The separation of the paving stones by selective attack of the bonding layer can be carried out by laser, by mechanical cutting assisted by a blade, and / or assisted by chemical treatment.
[0030] In some embodiments, the at least two tiles are successively placed on the first support substrate using a robot.
[0031] Particularly advantageously, the first support substrate has the same diameter as the second support substrate.
[0032] In some embodiments, the first support substrate comprises the same material as the second support substrate. Particularly advantageously, the first support substrate and / or the second support substrate may comprise silicon, glass, sapphire and / or polycrystalline silicon carbide.
[0033] In some embodiments, each tile comprises:
[0034] - 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 (AIP), or a IV or IV-IV material, in particular germanium or silicon carbide (SiC),
[0035] - a piezoelectric material, such as lithium tantalate (LiTaOs), lithium niobate (LiNbOs), potassium-sodium niobate (K x Nai-xNbO3 or KNN), barium titanate (BaTiOs), quartz, lead zirconate titanate (PZT), a compound of lead-magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN), and / or
[0036] - an electrically insulating material, such as diamond, strontium titanate, yttria zirconia or sapphire.
[0037] In some embodiments, the method further comprises:
[0038] - bonding the first donor pseudo-substrate, respectively the second donor pseudo-substrate, onto a third support substrate, by means of the blocks of the first donor pseudo-substrate, respectively the second donor pseudo-substrate,
[0039] - separating the paving stones into two portions of a third and a fourth thickness so as to retain 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.
[0040] 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.
[0041] 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 those skilled in the art.
[0042] Another object of the invention relates to a method for transferring tiles from a so-called pseudo-donor substrate to a receiving substrate comprising:
[0043] - the formation of a donor pseudo-substrate according to the method described above, - the formation of a weakening zone by implantation of atomic species in each block of the donor pseudo-substrate to define a portion to be transferred
[0044] - bonding of the donor pseudo-substrate to a recipient substrate,
[0045] - the transfer of a portion of the blocks from the donor pseudo-substrate to the recipient substrate by detaching each block along the weakening zone.
[0046] Particularly advantageously, the transferred portion of each block of the donor pseudo-substrate has a thickness of between 30 nm and 1.5 pm.
[0047] The receiving substrate advantageously comprises silicon, glass, sapphire, SiC, and / or AIN.
[0048] BRIEF DESCRIPTION OF THE FIGURES
[0049] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:
[0050] - figure 1 represents a top view and a sectional view of a support substrate on which a plurality of blocks of a donor substrate have been placed,
[0051] - Figures 2A to 2F represent an embodiment of the method for manufacturing donor pseudo-substrates according to the invention in which, successively, the cutting of blocks in a donor substrate (Figure 2A), the placement of said blocks on a first support substrate so as to form a first donor pseudo-substrate (Figure 2B), the bonding of said first donor pseudo-substrate with a second support substrate by means of the blocks of the first donor pseudo-substrate (Figure 2C) and the separation of the blocks into two portions of a first and a second thickness so as to form a second donor pseudo-substrate (Figure 2D), the bonding of the first donor pseudo-substrate on a third support substrate by means of the blocks of the first donor pseudo-substrate (Figure 2E) and the separation of the blocks into two portions of a third and fourth thickness so as to form a third donor pseudo-substrate (Figure 2F),
[0052] - Figures 3A to 3G represent another embodiment of the method according to the invention in which the bonding of a first donor substrate with a second donor substrate is successively carried out by means of a bonding layer so as to form a thick donor substrate (Figure 3A), the cutting of blocks in the thick donor substrate (Figure 3B), the bonding of said blocks on a first support substrate by means of the blocks of the first donor pseudo-substrate so as to form a first donor pseudo-substrate (Figure 3C), the bonding of said first donor pseudo-substrate with a second support substrate by means of the blocks of the first donor pseudo-substrate (Figure 3D) and the separation of the blocks into two portions of a first and a second thickness so as to form a second donor pseudo-substrate (Figure 3E),bonding the first donor pseudo-substrate to a third support substrate by means of the blocks of the first donor pseudo-substrate (figure 3F) and separating the blocks into two portions of a third and fourth thickness so as to form a third donor pseudo-substrate (figure 3G),
[0053] - Figures 4A to 40 represent a method of using said donor pseudo-substrates comprising successively the formation of a weakening zone in the blocks of one of said donor pseudo-substrates by atomic implantations so as to delimit a portion of the blocks to be transferred (Figure 4A), the bonding of the donor pseudo-substrate with a receiving substrate by means of the implanted blocks (Figure 4B) and the cutting of the donor pseudo-substrate along the weakening zone so as to transfer the portion of the blocks delimited by the weakening zone (Figure 40).
[0054] For readability reasons, the drawings are not necessarily drawn to scale.
[0055] DETAILED DESCRIPTION OF EMBODIMENTS
[0056] The invention relates to a method for manufacturing at least two substrates called donor pseudosubstrates.
[0057] In the present description, the term “donor pseudo-substrate” means a substrate comprising blocks placed on a support substrate, said donor pseudo-substrate being able to be used to transfer thin layers of the active material constituting the blocks onto a receiving substrate, for example by a Smart Cut™ type process.
[0058] The use of such a pseudo-donor substrate is of particular interest when the active material is not available in the form of large-sized substrates.
[0059] In the method according to the invention, a first pseudo-donor substrate is manufactured by placing at least two tiles on a support substrate. The other pseudo-donor substrates are manufactured from this first pseudo-donor substrate, by bonding the first pseudo-donor substrate to other support substrates via the tiles and by separating the tiles from said first donor substrate so as to transfer a portion thereof to each of the other support substrates. This advantageously makes it possible to avoid additional tile placement steps.
[0060] Subsequently, two embodiments of the method for manufacturing pseudo-donor substrates according to the invention are described in more detail. Since the invention extends to a method for transferring an active layer using one of these pseudo-donor substrates, an embodiment of such a transfer method is further described.
[0061] First embodiment of manufacturing donor pseudo-substrates Figures 2A to 2F schematically illustrate a first particular embodiment of the method according to the invention comprising the placement of the blocks P1, P2, P3 on a first support substrate 3 so as to form a first donor pseudo-substrate 1, the transfer of a first portion of the blocks P1, P2, P3 from the first donor pseudo-substrate 1 onto a second support substrate 4 so as to form a second donor pseudo-substrate 2, and finally the transfer of a second portion of said blocks onto a third support substrate 6 to form a third donor pseudo-substrate 7.
[0062] 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. It can in particular be carried out by sawing and / or cleaving, or even by laser cutting. It can also, for example, be combined with a step of partial plasma etching of the cutting lines, a technique known by the English term “plasma dicing”.
[0063] The cutting of the blocks P1-P3 in the donor substrate 5 is preferably carried out over the entire thickness of said donor substrate 5, so that each block P1-P3 has a thickness equal to the thickness of the donor substrate 5 from which they were cut.
[0064] Advantageously, the paving stones P1-P3 are made from a material that is not commercially available as a large donor substrate. Thus, the donor substrate 5 may have a diameter of less than 30 cm, for example of the order of 10 or 15 cm. This is particularly the case for III-V semiconductor materials, including nitrides (e.g., for binary compounds, indium nitride (InN), gallium nitride (GaN) and aluminum nitride (AIN)), arsenides (e.g., for binary compounds, indium arsenide (InAs), gallium arsenide (GaAs) and aluminum arsenide (AlAs)), and phosphides (e.g., for binary compounds, indium phosphide (InP), gallium phosphide (GaP) and aluminum phosphide (AIP)). This is also the case for IV or IV-IV semiconductor compounds, such as germanium and silicon carbide.
[0065] The P1-P3 blocks can also be made of a piezoelectric material, for example lithium tantalate (LiTaOs) or lithium niobate (LiNbOs), potassium-sodium niobate (K x Nai- x NbO3 or KNN), barium titanate (BaTiOs), quartz, lead zirconate titanate (PZT), a compound of lead-magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN) (non-exhaustive list). The P1-P3 blocks can also be made of an electrically insulating material, such as diamond, strontium titanate (SrTiO3), yttria zirconia (YSZ), or sapphire.
[0066] Each block P1-P3 has a minimum initial thickness of 100 pm, preferably an initial thickness of between 300 pm and 600 pm, more preferably an initial thickness of between 400 pm and 600 pm, this initial thickness also being advantageously equal to the thickness of the donor substrate 5.
[0067] Figure 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.
[0068] The first support substrate 3 advantageously has a diameter greater than the donor substrate 5. The first support substrate 3 comprises, for example, any material available in a substrate size greater than the donor material, such as silicon, glass, polycrystalline SiC, sapphire (AI2O3), 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 difference in size between the donor substrate 5 and the first support substrate 3, several donor substrates 5 may be necessary to tile the entire surface of the first support substrate 3 according to the desired tiling density.
[0069] The placement of each tile P1-P3 can be implemented by the “Pick and Place” technique, by which a robot picks up a tile previously cut from the donor substrate 5 and places it at a predetermined location on the first support substrate 3. The tiles P1-P3 are therefore placed successively on the first support substrate 3.
[0070] In some embodiments, each tile P1-P3 adheres to the first support substrate 3 by molecular adhesion. For this purpose, surface treatments of the tiles P1-P3 and / or of the first support substrate 3 may be implemented beforehand in order to promote good molecular adhesion. These treatments may include in particular cleaning, the deposition of a bonding layer such as a silicon oxide (SiC>2), plasma activation before bonding and annealing.
[0071] In other embodiments, the bonding of the tiles P1-P3 to the first support substrate 3 may involve an intermediate bonding layer, for example a polymer bonding layer, a eutectic bonding layer or a ceramic adhesive layer. Figure 2C illustrates the bonding of the first donor pseudo-substrate of Figure 2B to a second support substrate 5 via the tiles P1-P3.
[0072] 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 comprises for example any material available in a substrate size greater than the material of the donor substrate such as silicon, glass, polycrystalline SiC, AI2O3, or any other semiconductor material available in a large diameter and allowing the implementation of a bonding step.
[0073] In a particular embodiment of the bonding of the first donor pseudo-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 of the order of 300 mm, and / or the second support substrate 4 comprises the same material as the first support substrate 3.
[0074] Particularly advantageously, each block P1-P3 adheres to the second support substrate 3 by molecular adhesion. For this purpose, surface treatments of the blocks P1-P3 and / or of the second support substrate 4 may be implemented beforehand in order to promote good molecular adhesion. Depending on the materials considered, these treatments may include in particular cleaning, the deposition of a bonding layer such as a silicon oxide (SiC>2), plasma activation before bonding, and / or chemical mechanical polishing (CMP, acronym for the English term “Chemical Mechanical Polishing”). Furthermore, annealing is generally implemented after bonding to strengthen the adhesion.
[0075] Then, with reference to Figure 2D, the blocks 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 blocks having the first thickness e1 on the first donor pseudo-substrate 1 and to transfer a second portion P”1-P”3 of the blocks having the second thickness e2 onto the second support substrate 4 to form a second donor pseudo-substrate 2.
[0076] The second thickness e2 is between 20% and 80% of the initial thickness of the tiles P1-P3 of the first pseudo-donor substrate 1, so that the second thickness e2 is preferably between 20 pm and 560 pm, more preferably between 200 pm and 400 pm. The separation of the tiles P1-P3 can be carried out by mechanical cutting using a blade, by laser cutting or any other cutting technique compatible with the material to be cut. In any event, the separation of the tiles 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 of the order of 1 pm).
[0077] Thus, the method according to the invention advantageously makes it possible to manufacture two donor pseudo-substrates by implementing a single step of placing the tiles on a donor substrate using the “pick and place” technique. These “pick and place” steps being long and tedious, the method according to the invention is faster than a method which would consist of manufacturing each donor pseudo-substrate by placing tiles on a support substrate.
[0078] Optionally, the method according to this embodiment may further comprise bonding the first donor pseudo-substrate 1 (shown in FIG. 2E), onto a third support substrate 6, via the blocks P'1-P'3 of the first donor pseudo-substrate 1.
[0079] 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 comprises 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.
[0080] According to a particular embodiment of the bonding of the third support substrate 6 with the first pseudo-donor 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.
[0081] Particularly advantageously, each portion P'1-P'3 adheres to the third support substrate 6 by molecular adhesion. Since cutting causes 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'1-P'3 and / or of the third support substrate 6 may be implemented beforehand in order to promote good molecular adhesion. These treatments may include in particular cleaning, the deposition of a bonding layer such as a silicon oxide (SiC>2), plasma activation before bonding, and / or polishing (CMP). A person skilled in the art may choose the most suitable technique, in particular depending on the materials considered and / or the cutting technique.However, if the bonding technique does not require particularly low roughness, for example when a polymer adhesive is used, it is possible to dispense with surface treatment. Furthermore, annealing is generally carried out after bonding to strengthen adhesion.
[0082] With reference to Figure 2F, the method then further comprises separating the blocks P'1-P'3 into two portions of a third and a fourth thickness e3, e4 so as to retain a first portion of said blocks having the third thickness e3 on the first donor pseudo-substrate 1 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.
[0083] The fourth thickness of the second portion of paving stones is between 20% and 80% of the first thickness, respectively of the second thickness. The fourth thickness of the second portion of paving stones is preferably between 40 μm and 300 μm, more preferably between 100 μm and 250 μm.
[0084] In this case also, the separation of the paving stones P'1-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.
[0085] Alternatively or additionally to bonding the first donor pseudo-substrate 1 with a third support substrate 6 so as to form a third donor pseudo-substrate 7, the second donor pseudo-substrate 2 can also be bonded to a new support substrate so as to form an additional donor pseudo-substrate (not shown).
[0086] Thus, at this stage of the method according to the invention, it is possible to form up to four donor pseudo-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 during the formation of the first donor pseudo-substrate 1.
[0087] The number of pseudo-donor substrates that can be formed from the first pseudo-donor substrate depends on the initial thickness of the donor substrate and the accuracy of the cutting process. The pseudo-donor substrates thus formed can be used to transfer thin paving portions to a support substrate using the Smart Cut™ process.
[0088] The process of forming the pseudo-donor substrates can be repeated until pseudo-donor substrates with a tile thickness of between 50 pm and 200 pm are obtained, depending on the thickness that can be removed by the Smart Cut™ process and the number of possible recyclings of the pseudo-donor substrate.
[0089] Second embodiment of manufacturing pseudo-donor substrates
[0090] Figures 3A to 3G schematically illustrate a second embodiment of the method according to the invention comprising the placement of tiles P11, P12, P13 on a first support substrate 13 so as to form a first donor pseudo-substrate 11, then the transfer of a portion of the tiles P11, P12, P13 of said first donor pseudo-substrate 11 onto a second support substrate 14, to form a second donor pseudo-substrate 12.
[0091] According to this second embodiment of the invention, the bonding of a first donor substrate 18 with a second donor substrate 19 of the same diameter as the first donor substrate 18 is carried out by means of a bonding layer 20, to form a thick donor substrate 15 (shown in FIG. 3A).
[0092] Advantageously, the first donor substrate 18 and the second donor substrate 19 are made of a material which is not commercially available in the form of a large 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 of the order of 10 or 15 cm. This is particularly the case for III-V semiconductor materials, including nitrides (e.g., for binary compounds, indium nitride (InN), gallium nitride (GaN) and aluminum nitride (AIN)), arsenides (e.g., for binary compounds, indium arsenide (InAs), gallium arsenide (GaAs) and aluminum arsenide (AlAs)), and phosphides (e.g., for binary compounds, indium phosphide (InP), gallium phosphide (GaP) and aluminum phosphide (AIP)).This is also the case for IV or IV-IV semiconductor compounds, such as germanium and silicon carbide.
[0093] The first donor substrate 18 and second donor substrate 19 may also be made of a piezoelectric material, for example lithium tantalate (LiTaOs) or lithium niobate (LiNbOs), potassium-sodium niobate (K x Nai- x NbO3 or KNN), barium titanate (BaTiOs), quartz, lead zirconate titanate (PZT), a compound of lead-magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN) (non-exhaustive list).
[0094] The first donor substrate 18 and second donor substrate 19 may also be made of an electrically insulating material, such as, for example, diamond, strontium titanate (SrTiO3), yttria zirconia (YSZ), or sapphire.
[0095] The first donor substrate 18 and the second donor substrate 19 may be made of the same material or a different material.
[0096] 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.
[0097] The bonding layer 20 may be an oxide layer (an oxide / oxide bond being easy to implement industrially), a polymer bonding layer, a eutectic bonding layer or a ceramic glue layer, the material of said bonding layer being chosen to be able to withstand the subsequent cutting step and to be able to be removed selectively with respect to the material of the first and second donor substrates.
[0098] Referring to Figure 3B, blocks P11-P13 are then cut from the thick donor substrate 15, such that the initial thickness of each of said blocks P11-P13 is equal to the thickness of the thick substrate 15.
[0099] Each P11-P13 block has an initial thickness of between 400 and 1400 pm, preferably between 400 pm and 700 pm.
[0100] The cutting of the P11-P13 paving stones can be carried out using 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 partial plasma engraving of the cutting lines, a technique known by the English term "plasma dicing".
[0101] With reference to FIG. 3C, the tiles P11-P13 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 tiles P11-P13.
[0102] In the same way as in the first embodiment, the placement of each tile P11-P13 can be implemented by the “Pick and Place” technique, using a robot. The tiles P11-P13 are therefore placed successively on the first support substrate 13.
[0103] Each P11-P13 block can adhere to the first support substrate 13 by molecular adhesion following possible surface treatments of the P11-P13 blocks and / or of the first support substrate 13 (cleaning, deposition of a bonding layer such as a silicon oxide (SiC>2), plasma activation before bonding and annealing), or by means of an intermediate bonding layer (polymer bonding layer, eutectic bonding layer or ceramic adhesive layer).
[0104] With reference to Figure 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. In the same way as in the first embodiment, surface treatments of the blocks P11-P13 and / or of the second support substrate 14 may be implemented beforehand in order to promote good molecular adhesion (cleaning, deposition of a bonding layer such as a silicon oxide (SiC>2), plasma activation, polishing, etc.).
[0105] In the same way as in the first embodiment also, 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 substrate size greater than the material of the donor substrate such as silicon, glass, polycrystalline SiC, AI2O3, or any other semiconductor material available in large diameter. Optionally, the second support substrate 14 has the same diameter as the first support substrate 13, for example of the order of 300 mm, and / or the second support substrate 14 comprises the same material as the first support substrate 3.
[0106] The blocks P11-P13 are then separated into two portions of a first and a second thickness so as to keep a first portion of said blocks P11-P13 having the first thickness on the first donor pseudo-substrate 11 and to transfer a second portion of the blocks having the second thickness onto the second support substrate 14 to form a second donor pseudo-substrate 12.
[0107] Thus, in this embodiment also, the method advantageously makes it possible to manufacture two donor pseudo-substrates by having implemented only once the long and tedious step of placing the paving stones on a support substrate, for example by the “pick and place” method. The method 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.
[0108] With reference to Figure 3E, according to this second embodiment, the separation of the blocks P11-P13 preferably comprises a selective attack of the bonding layer 20. The separation of the blocks by selective attack of the bonding layer 20 can be implemented by laser, by mechanical cutting assisted by a blade, and / or assisted by chemical treatment. In any event, the separation of the blocks 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 of the order of 1 μm).
[0109] 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-mechanical polishing and / or planarization, is carried out to obtain a surface condition of the paving stones suitable for their subsequent use.
[0110] According to this embodiment also, the method according to the invention may further comprise:
[0111] - bonding the first donor pseudo-substrate 11, respectively the second donor pseudo-substrate 12, onto a third support substrate 16 via the blocks P'11-P'13 of the first donor pseudo-substrate 11, respectively the second donor pseudo-substrate 12 (shown in FIG. 3F in the case of the first donor pseudo-substrate 11, not shown in the case of the second donor pseudo-substrate 12),
[0112] - separating the blocks P'11 -P'13 into two portions of a third and a fourth thickness e13, e14 so as to keep a first portion of said blocks 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 blocks having the fourth thickness onto the third support substrate 16 to form a third donor pseudo-substrate 17 (shown in FIG. 3G in the case of the second donor pseudo-substrate 12).
[0113] This variant of the method according to the invention advantageously makes it possible to generate up to four donor pseudo-substrates by having implemented only once the step of placing the blocks on a support substrate, so as to form a first donor pseudo-substrate. According to other variants of the method, the first, second, third donor pseudo-substrates can still be bonded to other support substrates, so as to generate additional donor pseudo-substrates.
[0114] Preferably, all the donor pseudo-substrates resulting from the donor pseudo-substrate manufacturing process according to the invention have a block thickness of between 50 and 300 μm.
[0115] Method for transferring paving stones from a pseudo-donor substrate to a recipient substrate
[0116] The invention extends to a method of transferring tiles from a donor pseudo-substrate to a recipient substrate.
[0117] The method of transferring tiles comprises forming a donor pseudo-substrate according to any of the embodiments of the method of manufacturing a donor pseudo-substrate 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).
[0118] 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 Figure 3E) or after the formation of the third donor pseudo-substrate 17 (as shown in Figure 3G). The donor pseudo-substrate may also be the donor pseudo-substrate 12 (shown in Figure 3E) or the third donor pseudo-substrate 17 (shown in Figure 3G).
[0119] Alternatively, 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).
[0120] Preferably, the blocks of the donor pseudo-substrate of the block transfer method according to the invention have a thickness of between 50 μm and 300 μm. By way of example, the implementation of the rest of the block transfer method is shown in FIGS. 4A to 4C from the first donor pseudo-substrate 1 after the formation of the second donor pseudo-substrate 2.
[0121] With reference to Figure 4A, the method for transferring tiles according to the invention comprises the formation of a weakening zone 101 in each tile (in Figure 4A, tiles P'1 - P'3) of the previously manufactured pseudo-donor substrate (in Figure 4A, pseudo-donor substrate 1) in order to delimit a surface layer of said tiles C1, C2, C3 intended to be transferred onto a receiving substrate 102.
[0122] As shown diagrammatically by the arrows, the weakening zone 101 is advantageously formed by implantation of atomic species, such as hydrogen and / or helium, in the blocks, at a depth corresponding to the thickness of the layer C1, C2, C3 to be transferred.
[0123] The donor pseudo-substrate is then bonded to the recipient substrate 102, as illustrated in FIG. 4B, via the blocks.
[0124] The receiving substrate 102 has a diameter identical to the pseudo-donor substrate, for example of the order of 300 mm. The receiving substrate 102 comprises silicon, glass, sapphire, SiC, AIN and / or any other semiconductor material of interest and with a substrate size larger than that of the initial donor substrate.
[0125] To allow 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 ("grinding" in English terminology) in order to standardize the thickness of the paving stones, then to implement a smoothing process to make the surface of the paving stones compatible with bonding.
[0126] Particularly 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 support substrate may be implemented beforehand in order to promote good molecular adhesion.
[0127] With reference to FIG. 4C, the blocks are then detached along the weakening zone 101, in order to transfer the layers C1, C2, C3 delimited by said weakening zone 101 onto the receiving substrate 102. The transferred layers C1, C2, C3 generally have a thickness of between 30 nm and 1.5 pm.
[0128] Advantageously, the same donor pseudo-substrate is reused several times in the steps of forming a weakening zone, bonding and cutting along the weakening zone, so as to transfer at each implementation of said steps a new portion of the blocks of the donor pseudo-substrate onto a new receiving substrate 102.
[0129] Between each transfer, the surface of the paving stones formed during detachment along the weakening zone 101 is treated to achieve a roughness and a surface condition allowing good quality bonding on the new receiving substrate 102. For example, such a treatment may comprise, depending on the material of the paving stones: chemical-mechanical polishing, fine-grain abrasion, chemical removal, plasma treatment, deposition of a smoothing layer, and / or heat treatment. The implementation of such a surface treatment may consume, depending on the treatment considered, a thickness of paving stones of the order of 0.5 μm to 5 μm.
[0130] Preferably, several layer transfer cycles are successively implemented with the same donor pseudo-substrate, each cycle comprising the steps of forming a weakening zone, bonding, cutting along the weakening 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. The reuse of 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 therefore to limit the waste of said material.However, each cycle degrades the donor pseudo-substrate a little more (uniformity defects, modification of the uncured crystalline structure, degradation of the edges of the paving stones, breakage of the donor pseudo-substrate), the donor pseudo-substrate can only be reused a limited number of times. In practice, if less than 50% of the surface of the paving stones cannot be bonded, the donor pseudo-substrate is considered to be no longer usable.
[0131] Thus, the method for manufacturing a donor pseudo-substrate according to the invention advantageously makes it possible to form donor pseudo-substrates having an initial tile thickness that is lower than the donor substrate from which they are derived, made of the same material.
[0132] For example, the method for manufacturing pseudo-donor substrates, from an indium phosphide (InP) substrate 625 pm thick and 100 mm in diameter, makes it possible to manufacture pseudo-donor substrates having InP tiles with a minimum thickness of 100 pm, such that after 15 cycles, a thickness of 75 pm (at a rate of 5 pm per cycle) of said tiles has been consumed and only a thickness of 15 pm is discarded instead of a thickness of 550 pm if tiles with an initial thickness of 625 pm were used in the same number of cycles.
Claims
CLAIMS 1. Method for manufacturing two substrates called pseudo-donor substrates (1, 2) each comprising at least two blocks on a support substrate, the method comprising the following successive steps: - the placement, on a first support substrate (3), of at least two blocks (P1, P2), 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 donor pseudo-substrate (1) onto a second support substrate (4) via the blocks (P1, P2), - separating the paving stones 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 paving stones having the first thickness (e1) on the first donor pseudo-substrate and transferring a second portion (P”1, P”2) of the paving stones having the second thickness (e2) onto the second support 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. Method according to claim 1, further comprising cutting the at least two blocks (P1, P2) in a donor substrate (5), over the entire thickness of said donor substrate, so that the at least two blocks have a thickness equal to the thickness of the donor substrate from which they were cut.
3. Method according to claim 2, in which the donor substrate (5) has a diameter smaller than the diameters of the first support substrate (3) and the second support substrate (4).
4. Method according to one of claims 1 to 3, in which the separation of the blocks (P1, P2) is carried out by mechanical cutting using a blade or by laser cutting.
5. Method according to claim 1, comprising prior to placing the at least two blocks (P1, P2) on the first support substrate (3): - bonding a first donor substrate (18) to 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 the at least two blocks (P1, P2) in the thick donor substrate (15), so that the initial thickness of each of said blocks is equal to the thickness of the thick substrate.
6. Method according to claim 5, in which 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. Method according to any one of claims 5 or 6, in which the separation of the at least two blocks (P1, P2) comprises a selective attack of the bonding layer (20).
8. Method according to claim 7, in which the separation of the blocks by selective attack of the bonding layer is carried out by laser, by mechanical cutting assisted by a blade, and / or assisted by chemical treatment.
9. Method according to one of claims 1 to 8, in which the at least two blocks are placed successively on the first support substrate using a robot.
10. Method according to one of claims 1 to 9, in which the first support substrate has the same diameter as the second support substrate.
11. Method according to one of claims 1 to 10, in which the first support substrate comprises the same material as the second support substrate.
12. Method according to one of claims 1 to 11, in which the first support substrate and / or the second support substrate comprises silicon, glass, sapphire and / or polycrystalline SiC.
13. Method according to one of claims 1 to 12, in which each block (P1, 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 (AIP), or a IV or IV-IV material, in particular germanium or silicon carbide (SiC), - a piezoelectric material, such as lithium tantalate (LiTaOs), lithium niobate (LiNbOs), potassium-sodium niobate (K x Nai-xNbO3 or KNN), barium titanate (BaTiOs), quartz, lead zirconate titanate (PZT), a compound of lead-magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN), and / or - an electrically insulating material, such as diamond, strontium titanate, yttria zirconia or sapphire.
14. Method according to one of claims 1 to 13, further comprising: - bonding the first donor pseudo-substrate (1), respectively 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 the second donor pseudo-substrate, - separating the paving stones into two portions of a third (e3) and a fourth (e4) thickness so as to retain a first portion of said paving stones having the third thickness (e3) on the first donor pseudo-substrate (1), respectively on the second donor pseudo-substrate, and transferring 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).
15. Method according to claim 14, in which 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. Method according to one of claims 14 or 15, in which the separation of the blocks 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. Method for transferring paving stones from a so-called pseudo-donor substrate to a receiving substrate comprising: - the formation of a pseudo-donor substrate (1) according to one of claims 1 to 16, - the formation of a weakening zone (101) by implantation of atomic species in each block (P1, P2) of the donor pseudo-substrate to define a portion (C1, C2) to be transferred - bonding the donor pseudo-substrate (1) to a receiving substrate (102), - the transfer of a portion (C1, C2) of the blocks of the donor pseudo-substrate (1) onto the receiving substrate (102) by detaching each block (P1, P2) along the weakening zone (101).
18. Method according to claim 17, in which the portion (C1, C2) transferred from each block of the donor pseudo-substrate has a thickness of between 30 nm and 1.5 pm.
19. Method according to one of claims 17 or 18, in which the receiving substrate (102) comprises silicon, glass, sapphire, SiC, or AIN.