METHOD FOR MANUFACTURING A SUBSTRATE COMPRISING A PLURALITY OF PAVING PANELS

Abstract

The invention relates to a method for manufacturing a substrate (100), called a pseudo-donor substrate, comprising a plurality of first blocks (1) arranged at a distance from each other on a support substrate (3), comprising: - arranging, on the support substrate (3), said first blocks (1) and a plurality of second blocks (2) arranged between the first blocks (1) so that each edge of each first block (1) faces at least one second block (2), the first blocks (1) comprising a first material and the second blocks (2) comprising a second material different from the first material, and - chemical-mechanical polishing of the first and second blocks (1, 2). Figure for abstract: Fig 1

Description

Title of the invention: METHOD FOR MANUFACTURING A SUBSTRATE COMPRISING A PLURALITY OF PANELS Technical field

[0001] The invention relates to a method for manufacturing a substrate, called a pseudo-donor substrate, comprising a plurality of tiles, as well as a method for transferring chips from said tiles onto a receiving substrate. STATE OF THE ART

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

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

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

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

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

[0007] 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 an intermediate support, 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 receiving substrate via the blocks, and detaching each block along the weakening zone so as to transfer a portion of each block onto the receiving substrate.

[0008] To allow the donor pseudo-substrate to be bonded to the receiving substrate, the free surface of all the blocks must extend in the same plane. For this purpose, before bonding, chemical mechanical polishing (CMP) could be carried out, preferably preceded by mechanical abrasion (called grinding) of the donor pseudo-substrate. Chemical mechanical polishing combines a mechanical action of a polishing pad and a chemical action of a polishing solution to planarize the surface of all the blocks.

[0009] However, if the distance between the blocks is large, typically greater than or equal to 250 μm, the polishing pad, which has a certain flexibility, is partially inserted into the gap between the blocks and thus erodes the edges of the blocks. This rounding of the edges, which is called "edge rounding" in English, reduces the useful surface area of ​​the chips transferred to the receiving substrate. Conversely, the edges of the blocks very quickly degrade the polishing pad, which must therefore be renewed frequently. Summary of the invention

[0010] An aim of the invention is therefore to design a method for manufacturing a pseudo-donor substrate without rounding the edges of the paving stones, even when the paving stones are far from each other.

[0011] To this end, the invention proposes a method for manufacturing a substrate, called a donor pseudosubstrate, comprising a plurality of first blocks arranged at a distance from each other on a support substrate, comprising:

[0012] - the arrangement, on the support substrate, of said first blocks and of a plurality of second paving stones arranged between the first paving stones such that each edge of each first paving stone faces at least one second paving stone, the first paving stones comprising a first material and the second paving stones comprising a second material different from the first material, and

[0013] - a chemical-mechanical polishing of the first and second blocks.

[0014] By “different material” is meant in the present text a material having a different composition and / or a different crystalline quality.

[0015] The use of the second paving stones, which are advantageously formed from a less expensive material than that of the first paving stones, makes it possible to protect the edges of the first paving stones during mechanical-chemical polishing. They therefore make it possible to avoid rounding the edges of the first paving stones.

[0016] According to other advantageous but optional characteristics, possibly combined when technically possible:

[0017] - a distance between two adjacent first blocks is greater than or equal to 1 mm, preferably greater than or equal to 2 mm,

[0018] - a distance between each first tile and a second tile adjacent to said first paving is less than or equal to 250 pm, preferably less than or equal to 100 pm,

[0019] - the first material is a semiconductor material, such as a III-V material,

[0020] - the second material is a semiconductor material, such as silicon, said second material being chosen to have a difference in thermal expansion coefficient of zero or less than 40% in absolute value with the thermal expansion coefficient of the support substrate,

[0021] - the method optionally comprises, before the chemical-mechanical polishing, a depositing a layer of resin or polymer between the first paving stones and the second paving stones,

[0022] - the method comprises forming a weakening zone in the first paving stones, so as to delimit in each first paving stone a respective chip of the first material.

[0023] According to another aspect, the invention provides a pseudo-donor substrate capable of being obtained by the method described above.

[0024] Said substrate comprises a support substrate, a plurality of first tiles arranged at a distance from each other on the support substrate, and a plurality of second tiles arranged on the support substrate between the first tiles such that each edge of each first tile faces at least one second tile, the first tiles comprising a first material and the second tiles comprising a second material different from the first material, the free surface of each first tile being flush with the free surface of each second tile.

[0025] By "flush" is meant that the free surface of each first or second paving stone, which is flat, extends in the same plane. The free surface of a paving stone is the surface opposite the support substrate.

[0026] According to other advantageous but optional characteristics, possibly combined when technically possible:

[0027] - a distance between two adjacent first blocks is greater than or equal to 1 mm, preferably greater than or equal to 2 mm,

[0028] - a distance between each first tile and a second tile adjacent to said first paving is less than or equal to 250 pm, preferably less than or equal to 100 pm,

[0029] - the first material is a semiconductor material, such as a III-V material,

[0030] - the second material is a semiconductor material, such as silicon, said second material having a difference in thermal expansion coefficient of zero or less than 40% in absolute value with the thermal expansion coefficient of the support substrate,

[0031] - the substrate further comprises a layer of resin or polymer between the first paving stones and the second paving stones,

[0032] - each first block comprises a weakening zone delimiting a chip respective of the first material.

[0033] According to another aspect, the invention provides a method of transferring chips onto a receiving substrate.

[0034] Said method comprises:

[0035] - the formation of a pseudo-donor substrate by the method described above, in in which a weakening zone was formed in the first blocks in order to delimit a respective chip,

[0036] - bonding said donor pseudo-substrate to a recipient substrate via of the first paving stones, and

[0037] - the detachment of each first block along the weakening zone so as to transfer each chip onto the receiving substrate. BRIEF DESCRIPTION OF THE FIGURES

[0038] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:

[0039] - [Fig.l] illustrates a top view and a sectional view of a pseudo-substrate donor according to a first embodiment of the invention;

[0040] - Figures 2A to 2E illustrate different stages of the manufacture of a pseudo donor substrate according to the invention, respectively comprising the arrangement of the first and second tiles on a temporary support, the provision of the support substrate, the transfer of the first and second tiles from the temporary support to the support substrate, the implementation of a chemical-mechanical polishing of the first and second tiles, and the formation of a weakening zone in the first tiles to delimit chips of the first material;

[0041] - [Fig.3] illustrates the bonding of the donor pseudo-substrate onto a recipient substrate;

[0042] - [Fig.4] illustrates the structure formed from the receiving substrate and the chips resulting from the detachment of the paving stones along the weakened zone;

[0043] - [Fig.5] illustrates a top view and a sectional view of a pseudo-substrate donor according to a second embodiment of the invention;

[0044] - [Fig.6] illustrates a top view and a sectional view of a pseudo-substrate donor according to a third embodiment of the invention;

[0045] - [Fig.7] illustrates a top view and a sectional view of a pseudo-substrate donor according to a fourth embodiment of the invention.

[0046] For reasons of readability of the figures, the various elements have not necessarily been represented to scale. DETAILED DESCRIPTION OF EMBODIMENTS

[0047] The donor pseudo-substrate comprises two types of tiles arranged on a support substrate:

[0048] - paving stones of interest comprising a first material,

[0049] - dummy paving stones (called “dummies” in English) comprising a second material different from the first material or of lower crystalline quality allowing it to be less expensive.

[0050] All of said paving stones have a free surface extending in the same plane parallel to the main surface of the support substrate. In other words, the surface of the dummy paving stones is flush with the surface of the paving stones of interest.

[0051] The dummy blocks are not intended to produce electronic, optical or optoelectronic components, but to at least partially fill the gaps between the blocks of interest. Thus, by increasing the coverage rate of the support substrate by the blocks, the polishing pad can be kept in the plane of the free surface of the blocks and prevented from being inserted between blocks. Rounding of the edge of the blocks can therefore be avoided or at least minimized.

[0052] The use of such dummy blocks is particularly interesting when the distance between two adjacent blocks of interest is greater than or equal to 1 mm, and more preferably greater than or equal to 2 mm.

[0053] In a particularly advantageous manner, the distance between a block of interest and an adjacent dummy block is less than or equal to 250 μm, preferably less than or equal to 100 μm. Indeed, the polishing pad, even if flexible, cannot be introduced significantly between the block of interest and the dummy block. The polishing action is therefore limited to the free surface of the blocks and does not cause rounding of the edges of the blocks.

[0054] The paving stones of interest are generally made of an expensive material and available only in small dimensions. Optionally, the paving stones of interest may be made of a stack of such materials.

[0055] The blocks of interest may advantageously comprise at least one of said materials:

[0056] - a semiconductor material, such as a III-V material, in particular nitride indium nitride (InN), gallium nitride (GaN), aluminum nitride (AIN), indium arsenide (InAs), gallium arsenide (GaAs), aluminum arsenide (AlAs), indium phosphide (InP), gallium phosphide (GaP) or aluminum phosphide (AlP), or a material IV or IV-IV, including germanium or silicon carbide (SiC),

[0057] - a piezoelectric material, such as lithium tantalate (LiTaO3), lithium niobate (LiO3), lithium (LiNbO3), potassium sodium niobate (KxNahxNbO3 or KNN), barium titanate (BaTiO3), quartz, lead zirconate titanate (PZT), a compound of lead magnesium niobate and lead titanate (PMN-PT), zinc oxide (ZnO), aluminum nitride (AIN) or aluminum scandium nitride (AIScN), and / or

[0058] - an electrically insulating material, such as diamond, strontium titanate, yttria-containing zirconia or sapphire.

[0059] Since the dummy paving stones are only intended to fill the gaps between the paving stones of interest, they are made of a material different from that of the paving stones of interest or of lower crystalline quality, which is advantageously less expensive than that of the paving stones of interest, and readily available.

[0060] Preferably, the material of the dummy paving stones is further chosen to exhibit behavior compatible with that of the paving stones of interest during chemical-mechanical polishing and / or during use of the donor pseudo-substrate.

[0061] Thus, for example, the material of the dummy paving stones advantageously exhibits behavior with respect to mechanical-chemical polishing (i.e. in particular in terms of polishing speed) comparable to that of the material of the paving stones of interest, so as not to cause a shift between the free surface of the paving stones of interest and the dummy paving stones during polishing.

[0062] Furthermore, the material of the dummy paving stones advantageously has a coefficient of thermal expansion close to that of the paving stones of interest, so as not to cause deformation of the support substrate during heat treatments undergone by the pseudo-donor substrate. By close coefficients of thermal expansion is meant coefficients of thermal expansion that are equal or have a difference of less than 40% in absolute value.

[0063] For example, the dummy blocks may be made of silicon.

[0064] In other examples, the dummy tiles may have a composition similar to that of the tiles of interest, but a lower quality. For example, the tiles of interest may be made of a monocrystalline III-V material and the dummy tiles of a polycrystalline III-V material or of lower crystalline quality.

[0065] [Fig.l] illustrates a top view and a sectional view of a donor pseudo-substrate according to a first embodiment.

[0066] The donor pseudo-substrate comprises a support substrate 3 on which are arranged blocks of interest 1 and dummy blocks 2.

[0067] The blocks of interest 1 are arranged at regular intervals, with a distance dl between the closest edges of two adjacent blocks. It should be noted, however, that this arrangement of the blocks of interest is given for illustration purposes only; thus, the blocks of interest may possibly have different shapes, or be arranged at different distances from each other. Furthermore, the blocks of interest are not necessarily square as illustrated in [Fig.l], but may have any other shape suitable for the intended use, with or without a straight edge. For example, the blocks of interest may have a rectangular, circular shape, or any other shape composed of lines and / or curves.

[0068] The distance dl is advantageously greater than or equal to 1 mm, preferably greater than or equal to 2 mm.

[0069] Dummy blocks 2 are arranged between the blocks of interest 1, so that the edge of each block of interest is opposite the edge of a dummy block. There is thus a distance d2 between the edge of a block of interest and the closest edge of a dummy block, which is much less than the distance dl.

[0070] For example, the distance d2 is less than or equal to 250 pm, preferably less than or equal to 100 pm.

[0071] In the embodiment of [Fig.l], the blocks of interest having four rectilinear edges, four dummy blocks with rectilinear edges are arranged around a block of interest. The edge of each dummy block is arranged opposite a respective edge of the block of interest, parallel to it in order to have a constant distance d2 between the block of interest and the respective dummy block. Thus, at any point on the perimeter of the block of interest, the distance with each adjacent block is at most equal to d2. The remaining free space between the blocks is then sufficiently restricted to prevent the polishing pad from being inserted between the blocks and eroding the edges of the blocks.

[0072] For example, the tiles of interest may have a size of 3x3 mm2 and be spaced by a distance dl equal to 7 mm. The dummy tiles then advantageously have a size of 6.5x3 mm2, so that the distance d2 between a tile of interest and a dummy tile is equal to 0.25 mm.

[0073] Figures 2A to 2E illustrate steps in the manufacture of the pseudo-donor substrate of [Fig.l]. To facilitate the alignment of the tiles of interest and the dummy tiles, it is advantageous to first assemble the tiles of interest and the dummy tiles on a temporary support and then transfer said tiles from the temporary support to the support substrate.

[0074] With reference to [Fig.2A], the interest blocks 1 and the dummy blocks 2 are all first placed on a temporary support.

[0075] The temporary support is for example formed from one of the following materials: adhesive tape held by a frame, silicon substrate, glass substrate (non-limiting list).

[0076] The tiles of interest and the dummy tiles may be cut from one or more respective donor substrates, and placed on the temporary support using a robot (a technique known as "Pick and Place"). Advantageously, the tiles have the same thickness as the respective donor substrate.

[0077] With reference to [Fig.2B], the support substrate 3 is provided.

[0078] With reference to [Fig.2C], the blocks 1, 2 are glued onto the support substrate 3 by through their free surface, then the temporary support is removed so as to expose the opposite surface of the pavers. Advantageously, the bonding of the pavers to the support substrate is direct, but it is possible to use a bonding layer between the pavers and the support substrate.

[0079] Alternatively, it is possible to directly assemble the paving stones onto the support substrate with sufficient precision using the robot by using alignment marks arranged on the support substrate. This avoids the use of the temporary support and the transfer of the paving stones from the temporary support to the support.

[0080] With reference to [Fig.2D], a chemical-mechanical polishing of the free surface of the paving stones of interest and the dummy paving stones is carried out. As shown schematically, due to the small distance between the paving stones, the polishing pad 5 acts essentially in the plane of the free surface of the paving stones, without inserting itself between the paving stones. Consequently, the edges of the paving stones, in particular the paving stones of interest, remain straight (not rounded).

[0081] Optionally, this chemical-mechanical polishing may be preceded by a step of planarization of the paving stones by mechanical abrasion (“grinding”). Such planarization may in particular be advantageous when the paving stones have different thicknesses, in order to bring their free surface substantially into the same plane, or to reduce the thickness of the paving stones. However, if the paving stones have coplanar free surfaces, it is possible to dispense with such planarization and to implement chemical-mechanical polishing directly.

[0082] Optionally, before the chemical-mechanical polishing, a layer of resin or polymer (not shown) can be deposited between the blocks of interest and the dummy blocks, so as to fill the gaps between said blocks.

[0083] With reference to [Fig.2E], a weakening zone 10 is formed in the blocks of interest 1 (and possibly in the dummy blocks 2) delimiting a surface chip 11 in each block. Said weakening zone is advantageously obtained by implantation of ionic species (for example hydrogen and / or helium), shown diagrammatically by the arrows, in the blocks.

[0084] The formation of the weakening zone is preferably carried out after the chemical-mechanical polishing, but it can optionally be carried out before.

[0085] A pseudo-donor substrate 100 is thus obtained which can subsequently be bonded to a receiving substrate to transfer the chips thereto. The receiving substrate is typically a semiconductor substrate, for example a silicon substrate, solid or comprising microelectronic or optoelectronic devices.

[0086] With reference to [Fig.3], the free surface of the paving stones is glued to the receiving substrate 6. Advantageously, the gluing of the paving stones to the receiving substrate is direct, but it is possible to use a layer of glue between the paving stones and the receiving substrate.

[0087] With reference to [Fig.4], the tiles of interest 1 are detached along the weakening zone 10, so as to transfer the chips 11 onto the receiving substrate 6 by the Smart Cut™ process. The detachment can be initiated by a heat treatment, a mechanical and / or chemical action at the weakening zone.

[0088] Figures 5 to 7 illustrate other embodiments of the pseudo-donor substrate.

[0089] In the case of [Fig.5], the blocks of interest have a very large spacing (typically greater than 10 mm) and the number and size of the dummy blocks has been minimized compared to the embodiment of [Fig.l]. Each block of interest is surrounded by four dummy blocks which protect each of its edges during chemical-mechanical polishing, but the gap between two blocks of interest is not entirely filled by the dummy blocks. There therefore remains a gap between two adjacent dummy blocks, between which the polishing pad can possibly be inserted, but the edge rounding effect will only apply to the dummy blocks and will therefore not be harmful to the blocks of interest.

[0090] To effectively protect the paving stones of interest, the dummy paving stones advantageously have a width (in the direction perpendicular to the edge of the paving stone of interest opposite which they are arranged) greater than or equal to 10 mm. The other dimension of the dummy paving stones (in the direction parallel to the edge of the paving stone of interest opposite which they are arranged) is advantageously equal to that of the paving stones of interest.

[0091] For example, if the tiles of interest have a size of 3x3 mm2 and are spaced 20 mm apart, they can be surrounded by dummy tiles of 10x3 mm2.

[0092] According to another example, if the tiles of interest have a size of 10x10 mm2 and are spaced 50 mm apart, they can be surrounded by dummy tiles of 10 up to 25 xl0 mm2.

[0093] It will be noted that the corners of the blocks are less subject to rounding during chemical-mechanical polishing. Consequently, it is sufficient to protect the edges of the blocks of interest with the dummy blocks to avoid their rounding and thus the reduction of the useful surface area of ​​the chips.

[0094] [Fig.6] illustrates another embodiment, in which the dummy paving stones come in different shapes and sizes.

[0095] In particular, in this embodiment, the dummy paving stones have a larger dimension than that of the paving stones of interest, in order to better protect the corner of the paving stones of interest against the action of the polishing pad.

[0096] [Fig.7] illustrates another embodiment, in which the same dummy paving stone in the form of a single strip is arranged between two parallel rows of paving stones of interest.

[0097] This embodiment makes it possible to reduce the number of dummy paving stones required, since the same dummy paving stone in the form of a strip simultaneously protects the edge of several paving stones of interest.

[0098] It is thus possible to reduce the assembly time of the dummy paving stones compared to the embodiment of [Fig.l].

[0099] These different figures are only intended to illustrate different ways of arranging the dummy paving stones around the paving stones of interest in order to protect the edges of the paving stones of interest from erosion caused by the polishing pad, but the person skilled in the art may choose other arrangements of the dummy paving stones depending on the shape and arrangement of the paving stones of interest, provided that he plans for each edge of the paving stones of interest to be opposite a sufficiently close dummy paving stone. This choice may in particular depend on a compromise between the quantity of material consumed to form the dummy paving stones and the time required to position the dummy paving stones between the paving stones of interest.

Claims

Claims

1. Method for manufacturing a substrate (100), called a pseudo-donor substrate, comprising a plurality of first blocks (1) arranged at a distance from each other on a support substrate (3), comprising: - arranging, on the support substrate (3), said first blocks (1) and a plurality of second blocks (2) arranged between the first blocks (1) so that each edge of each first block (1) faces at least one second block (2), the first blocks (1) comprising a first material and the second blocks (2) comprising a second material different from the first material, and - chemical-mechanical polishing of the first and second blocks (1, 2).

2. Method according to claim 1, in which a distance (dl) between two adjacent first blocks is greater than or equal to 1 mm, preferably greater than or equal to 2 mm.

3. Method according to one of claims 1 or 2, in which a distance (d2) between each first tile (1) and a second tile (2) adjacent to said first tile is less than or equal to 250 pm, preferably less than or equal to 100 pm.

4. A method according to one of claims 1 to 3, wherein the first material is a semiconductor material, such as a III-V material.

5. Method according to one of claims 1 to 4, in which the second material is a semiconductor material, such as silicon, said second material being chosen to have a difference in thermal expansion coefficient of zero or less than 40% in absolute value with the thermal expansion coefficient of the support substrate.

6. Method according to one of claims 1 to 5, comprising, before planarization, a deposition of a layer of resin or polymer between the first paving stones (1) and the second paving stones (2).

7. Method according to one of claims 1 to 6, comprising the formation of a weakening zone (10) in the first blocks, so as to delimit in each first block a respective chip (11) of the first material.

8. Substrate (100), called pseudo-donor substrate, comprising a support substrate (3), a plurality of first blocks (1) arranged at a distance from each other on the support substrate (3), and a plurality of second blocks (2) arranged on the support substrate (3) between the first blocks (1) so that each edge of each first block (1) faces at least one of the first blocks (1) and at least one of the second blocks (2). at least one second paving stone (2), the first paving stones (1) comprising a first material and the second paving stones (2) comprising a second material different from the first material, the free surface of each first paving stone being flush with the free surface of each second paving stone.

9. Substrate according to claim 8, in which a distance (dl) between two adjacent first blocks is greater than or equal to 1 mm, preferably greater than or equal to 2 mm.

10. Substrate according to one of claims 8 or 9, in which a distance (d2) between each first tile and a second tile adjacent to said first tile is less than or equal to 250 pm, preferably less than or equal to 100 pm.

11. Substrate according to one of claims 8 to 10, in which the first material is a semiconductor material, such as a III-V material.

12. Substrate according to one of claims 8 to 11, in which the second material is a semiconductor material, such as silicon, said second material having a difference in thermal expansion coefficient of zero or less than 40% in absolute value with the thermal expansion coefficient of the support substrate.

13. Substrate according to one of claims 8 to 12, further comprising a layer of resin or polymer between the first blocks (1) and the second blocks (2).

14. Substrate according to one of claims 8 to 13, in which each first block (1) comprises a weakening zone (10) delimiting a respective chip (11) of the first material.

15. Method for transferring chips (11) of a first material onto a receiving substrate (6), comprising: - forming a donor pseudo-substrate (100) by the method according to claim 7, - bonding said donor pseudo-substrate (100) onto a receiving substrate (6) via the first blocks (1), and - detaching each first block (1) along the weakening zone (10) so as to transfer each chip (11) onto the receiving substrate (6).

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