METHOD FOR MANUFACTURING A STRUCTURE COMPRISING A MULTIPLE BURIED cavities
The manufacturing process for MEMS devices with buried cavities addresses the challenge of high-quality thin layer transfer by forming a functional buried fragile plane with distinct zones to control microcrack growth, achieving improved reliability and reduced defects.
Patent Information
- Application Number
- FR2023002184
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-03-09
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2043-03-09
AI Technical Summary
Existing layer transfer processes for MEMS devices with buried cavities face challenges in achieving high-quality thin layer transfers due to microcrack formation, blisters, and local exfoliations, particularly when dealing with small cavities and thin layers.
A manufacturing process that forms a functional buried fragile plane with distinct zones, differing in stiffness effect, by localized species implantation, to control microcrack growth and promote high-temperature separation, ensuring a high-quality thin layer transfer with reduced defects.
The process enhances the quality of thin layer transfer by minimizing defects and enabling high-temperature separation, resulting in a structure with improved reliability and reduced microcrack formation.
Smart Images
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Abstract
Description
Title of the invention: METHOD FOR MANUFACTURING A STRUCTURE COMPRISING A PLURALITY OF CAVITIES BURIED FIELD OF INVENTION
[0001] The present invention relates to the field of microelectronics and microelectromechanical systems. In particular, the present invention relates to a method for collectively manufacturing a plurality of cavities embedded within a structure comprising a support substrate and a thin film, the cavities being confined between the support substrate and the thin film.
[0002] TECHNOLOGICAL BACKGROUND OF THE INVENTION
[0003] MEMS devices (Microelectromechanical Systems, according to Anglo-Saxon terminology) are widely used for manufacturing various sensors for a multitude of applications: examples include pressure sensors, microphones, radio frequency switches, electroacoustic and ultrasonic transducers (e.g., pMUT, "Piezoelectric Micromachined Ultrasonic Transducer"), etc. Many of these MEMS devices are based on a flexible membrane positioned over a cavity. During operation, the deflection of the membrane, linked to a physical parameter (e.g., the propagation of an acoustic wave for a pMUT), is converted into an electrical signal (or vice versa, depending on whether the device is in receiver or transmitter mode).
[0004] Several layer transfer methods exist for obtaining a structure comprising a thin layer (which will form the aforementioned membrane) overlying a plurality of cavities. These methods are advantageously based on the direct bonding (i.e., without the addition of adhesive) of a donor substrate and a support substrate at their respective front faces. One or the other of the substrates comprises cavities opening onto its front face, typically the support substrate. These cavities are sealed during the molecular adhesion assembly step of the two substrates. A thinning step of the donor substrate results in the transfer of a thin layer onto the support substrate.This thinning step can be based on the Smart Cut™ process, which employs a buried fragile plane, formed by implanting lightweight materials into the donor substrate. This plane, along with the front face of the donor substrate, delineates the thin layer to be transferred (typically less than 2 sq m thick). As is well known, the growth of microcracks in the buried fragile plane, through thermal and / or mechanical activation, leads to separation along the plane, resulting in the transfer. of the thin layer onto the support substrate. The remainder of the donor substrate can be reused for a subsequent layer transfer.
[0005] Obtaining a high-quality thin film transfer is nevertheless complex due to the presence of cavities, above which there is no stiffening effect. The stiffening effect is attributed here to the presence of the front face of the support substrate in contact with the thin film.
[0006] Thus, the growth of microcracks in the buried fragile plane can generate, directly above the cavities, blisters or even local exfoliations which irreversibly degrade the thin layer and correspond to transfer defects.
[0007] The quality of the transfer is all the more difficult to ensure as the size of the cavities increases. Typically, lateral dimensions of cavities are on the order of a few microns to several tens of microns, with a thin film thickness remaining less than 2 pm.
[0008] SUBJECT OF THE INVENTION
[0009] The present invention proposes a method for collectively manufacturing a structure comprising a plurality of buried cavities, covered by a high-quality thin layer, i.e., one exhibiting a very low number of transfer defects. It is based on the formation of a buried, so-called functional, brittle plane, the characteristics and properties of which differ between first and second zones, which may or may not benefit from a stiffening effect: the objective is to decouple the maturation of microcracks in these two zones, in order to promote the quality of the layer transfer.
[0010] BRIEF DESCRIPTION OF THE INVENTION
[0011] The present invention relates to a method for manufacturing a structure comprising a plurality of cavities confined between a thin layer and a supporting substrate, the manufacturing method comprising the following steps:
[0012] a) the supply of a donor substrate and a support substrate, each of the substrates having a front face and a rear face;
[0013] b) the implantation of first light species in the donor substrate, to form a uniform buried fragile plane delimiting with the front face of the donor substrate, the thin layer to be transferred;
[0014] c) the localized implantation of second species in the donor substrate so as to introduce said second species into the uniform buried fragile plane only at the level of second zones, to form a functional buried fragile plane having:
[0015] - of the first zones containing the first light species and not the second species, and
[0016] - the second zones, comprising the first light species and the second species ;
[0017] d) the formation of a plurality of cavities opening at the level of a front face of the donor substrate or the supporting substrate;
[0018] e) the assembly by direct bonding of the donor substrate onto the support substrate, at the level of their respective front faces, to form a bonded structure in which the cavities are located directly above either the first zones or the second zones of the functional buried fragile plane;
[0019] f) the application of a heat treatment to the bonded structure to cause spontaneous separation along the functional buried brittle plane and to form on the one hand the structure and on the other hand the rest of the donor substrate.
[0020] According to advantageous features of the invention, taken alone or in any feasible combination: • the implantation of step c) is carried out in the presence of a mask, placed on the front face of the donor substrate, directly above the first zones of the functional buried fragile plane; • the formation of cavities in step d) is carried out by local etching of the front face of the support substrate, for example by means of a mask placed on said front face; • after step c), step d) of cavity formation includes the etching of the front face of the donor substrate, directly above the second zones, the first zones being protected from etching by the mask; • the process includes, after step d) and after removal of the mask, a step c') of localized implantation of third species at the level of the front face of the donor substrate, the third species thus being implanted in the first zones of the functional buried fragile plane and in another buried plane located at a distance and under the second zones of the functional buried fragile plane; • Step d) of cavity formation is carried out before step c), and includes: • the application of a mask placed on the front face of the donor substrate, directly above the second zones of the functional buried fragile plane intended to be formed in subsequent step c), and • the engraving of the front face of the donor substrate, directly above the first zones, the second zones being protected from the engraving by the mask; • After step d) and after removing the mask from the front face of the donor substrate, step c) of implantation is carried out, the second species being thus implanted in the second zones of the functional buried fragile plane and in another buried plane located at a distance and below the first
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[0036] areas of the fragile, buried, functional plan; • the second zones of the functional buried fragile plane are directly above the cavities, in the glued structure, and the first light species are hydrogen ions or atoms, and the second species are helium ions or atoms; • the first zones of the functional buried brittle plane are directly above the cavities in the bonded structure, the first light species are hydrogen ions or atoms, or helium ions or atoms, or hydrogen and helium ions or atoms, and the second species are silicon ions or atoms, which are likely to slow down the growth kinetics of microcracks in the second zones of the functional buried brittle plane, compared to the growth kinetics of microcracks in the first zones; • step e) of assembly involves at least one intermediate layer disposed on the donor substrate and / or on the support substrate, said intermediate layer having been deposited after one of steps a) to d). Brief description of the drawings Other features and advantages of the invention will become apparent from the detailed description that follows, with reference to the accompanying figures in which: [Fig.1] Fig.1 presents two structures produced according to the manufacturing process conforming to the present invention; [Fig.2a] [Fig.2b] [Fig.2c] [Fig.2d] [Fig.2e] [Fig.2f] Figures 2a to 2f show steps in the manufacturing process according to a first embodiment of the present invention; [Fig.3a] [Fig.3b] [Fig.3c] [Fig.3d] [Fig.3e] [Fig.3f] Figures 3a to 3f show steps in the manufacturing process according to a second embodiment of the present invention;
[0037] [Fig.4a]
[0038] [Fig.4b]
[0039] [Fig.4d]
[0040] [Fig.4c]
[0041] [Fig.4e]
[0042] [Fig.4f]
[0043] Figures 4a to 4f show steps of the manufacturing process according to a third embodiment of the present invention; note that step d) ([Fig.4d]) occurs before step c) ([Fig.4c]) in this third embodiment;
[0044] [Fig.5] Fig.5 presents top-view images of SOI structures with cavities not in accordance with the invention, obtained after the application of isothermal annealing at different temperatures;
[0045] [Fig.6a]
[0046] [Fig.6b]
[0047] [Fig.6c]
[0048] [Fig.6d]
[0049] [Fig.6c']
[0050] [Fig.6e]
[0051] [Fig.6f]
[0052] Figures 6a to 6f show steps of the manufacturing process according to a variant of the first embodiment of the present invention; note that an additional step c') is added after step d) in this variant, compared to the first embodiment illustrated in Figures 2a to 2f.
[0053] Some figures are schematic representations which, for the sake of clarity, are not to scale. In particular, the layer thicknesses along the z-axis are not to scale with respect to the lateral dimensions along the x and y axes. The same reference numerals in the figures may be used for elements of the same nature. DETAILED DESCRIPTION OF THE INVENTION
[0054] The invention relates to a method for manufacturing a structure 100 comprising a plurality of cavities 30 confined between a thin film 10 and a support substrate 20, as illustrated in [Fig. 1]. The structure 100 may optionally comprise at least one intermediate layer 50 between the thin film 10 and the support substrate 20.
[0055] A first step a) of the manufacturing process consists of providing a donor substrate 11, from which the thin film 10 will be transferred, and a support substrate 20 ([Fig.2a], [Fig.3a], [Fig.4a], [Fig.6a]).
[0056] The donor substrate 11 and the support substrate 20 advantageously have the shape of a wafers, typically with a diameter greater than 100mm, for example 150mm, 200mm or 300mm, and each have a front face 1 la,20a and a back face 1 lb,20b. Their thickness is usually between 200 and 900 microns.
[0057] The donor substrate 11 may be formed of at least one material selected from silicon, germanium, III-V semiconductor compounds, silicon carbide, lithium tantalate, lithium niobate, or other material of interest for the intended application. The support substrate 20 may be formed of at least one material selected from silicon, germanium, III-V semiconductor compounds, silicon carbide, lithium tantalate, lithium niobate, a glass, a ceramic, or other material of interest for the intended application.
[0058] The next step b) of the process involves implanting first light species into the donor substrate 11, across its entire front face lia (in other words, across the entire surface or "full plate"), so as to form a uniform buried fragile plane 12', which, together with said front face lia, delimits the thin layer 10 to be transferred ([Fig. 2b], [Fig. 3b], [Fig. 4b], [Fig. 6b]). The term uniform here means that the implantation characteristics are the same over the entire extent of the buried fragile plane 12'.
[0059] These light species can notably be selected from among hydrogen and / or helium ions or atoms. As is well known with reference to the Smart Cut™ process, these first species, once implanted in the donor substrate 11, are capable of forming lenticular defects in the uniform buried brittle plane 12'; these defects are likely to develop as microcracks, under thermal activation, through diffusion of the light species and coalescence of the lenticular defects. It should be noted that the lenticular defects are distributed in a thin layer buried in the donor substrate 11 and determined by the Gaussian implantation profile; this layer is called the buried brittle plane for the sake of simplicity.
[0060] The implantation energy defines the depth at which the uniform buried brittle plane 12' will be generated in the donor substrate 11. For a given implantation energy and a given material of the donor substrate 11, the implanted dose of light species is the essential parameter defining the development kinetics of microcracks, i.e. the blistering kinetics (without stiffener) and fracture kinetics (in the presence of a stiffener).
[0061] The applicant has identified that, for obtaining a high-quality thin film transfer 10 in a cavity structure 100, the required characteristics and properties of the buried brittle plane differ depending on whether said plane is located directly above a region benefiting from a stiffening effect or directly above a cavity (therefore without a stiffening effect). In regions benefiting from a stiffening effect, it It appears advantageous to slow down the fracture kinetics, allowing the use of relatively high temperatures during heat treatment to induce spontaneous separation in the buried brittle plane, while maintaining controllable treatment times. A higher temperature also allows for greater pressure buildup on the microcracks and promotes the continuity of the fracture wave. In areas lacking a stiffening effect (directly above cavities), it is advantageous for the development of microcracks during the aforementioned heat treatment to lead to large blisters without premature local exfoliation.
[0062] This objective is approached by implementing the manufacturing process according to the invention which provides for the production of a functional buried fragile plan 12 comprising first zones ZI different from second zones Z2, in terms of doses and / or nature of the species implanted.
[0063] Step c) of the process corresponds to a localized implantation of second species in the donor substrate 11 so as to introduce said second species into the uniform buried fragile plane 12' only at the level of second zones Z2. This makes it possible to form the functional buried fragile plane 12 ([Fig.2c], [Fig.3c], [Fig.4c], [Fig.6c]). The latter then presents, in the (x,y) plane of the front face 1:
[0064] - the first ZI zones containing the first light species and not the second species, and
[0065] - the second zones Z2, comprising the first light species and the second species.
[0066] The second species may be of the same nature as the first species or of a different nature. The implantation energy used to introduce the second species is adjusted so that their implantation profile substantially overlaps with the implantation profile of the first light species. Advantageously, the maxima of the implantation profiles of the first and second species are located at depths equal to + / -20%, or even more advantageously, at + / -10%.
[0067] Localized implantation can be achieved by various means. A first option, implemented in a first and second embodiment of the invention ([Fig. 2c], [Fig. 3c]), consists of using a mask (M), applied to the front face 1 of the donor substrate 11, so as to protect the first ZI zones of the implantation. Such a mask is conventionally formed using deposition, lithography, and etching techniques. Another option, illustrated in [Fig. 4c], with reference to a third embodiment of the invention, is to take advantage of a difference in relief on the front face 1a, between the regions directly above the first ZI zones and those directly above the second Z2 zones, so as to locate the second species in the second Z2 zones of the functional buried fragile plane 12 and to implant them Introduce at a distance and below the first zones of said plan 12, in another discontinuous buried plan 12". The second species will then be able to contribute to the characteristics and properties of the second zones Z2 but not (or in a very limited way) to those of the first zones Z1.
[0068] During a step d) of the process, a plurality of cavities 30 is formed at the front face 1 of the donor substrate 11 (1st and 3rd embodiments, [Fig.2d], [Fig.6d] and [Fig.4d]) or at that 20a of the support substrate 20 (2nd embodiment, [Fig.3d]).
[0069] It is important to note that step d) can be carried out after step c) (1st embodiment, [Fig.2d], [Fig.6d]) or before step c) (3rd embodiment, [Fig.4d]) or even in parallel with step c) (2nd embodiment, [Fig.3d]).
[0070] The formation of cavities in one of the substrates is classically carried out by local etching of the front face 1 la,20a, for example by means of a mask (M, M') disposed on said front face lia,20a.
[0071] The depth of the cavities 30 can typically vary between 100 nm and 100 pm. Their shape, in the (x,y) plane of the front face 11a,20a of the substrate concerned 11,20, can be circular, square, rectangular, or polygonal. The characteristic dimension(s) (or lateral dimension(s)) of a cavity 30 in the (x,y) plane, namely its diameter (for a circular shape) or its side (for a square shape) or its width and length (for a rectangular shape), is / are typically between 1 pm and 500 pm. The spacing between the cavities 30 can be between 1 pm and a few hundred mm.
[0072] The 1st and 3rd embodiments, which provide for the formation of cavities 30 in the donor substrate 11 ([Fig.2d], [Fig.4d]), have the advantage of requiring only one mask (M) for the execution of steps c) and d). These embodiments nevertheless limit the range of possible cavity depths, because the depth must remain less than the difference between the depth of the functional buried fragile plane 12 and the target thickness of the thin layer 10 to be transferred.
[0073] The second embodiment provides for the formation of cavities 30 in the support substrate 20 ([Fig. 3d]). In this case, it is necessary that the mask M' used to define the position of the cavities 30 on said substrate 20 and the mask M used to define the position of the first and second zones Z1,Z2 allow the correspondence between cavities 30 and first or second zones Z1,Z2 during the subsequent assembly step.
[0074] The manufacturing process then comprises a step e) of assembly by direct bonding of the donor substrate 11 onto the support substrate 20, at their respective front faces 1a, 20a, to form a bonded structure 90 ([Fig. 2e], [Fig. 3e], [Fig. 4e], [Fig. 6e]). A bonding interface 40, devoid of adhesive material, is defined between the two sides assembled.
[0075] The cavities 30 are located directly above either the first zones Z1 or the second zones Z2 of the functional buried fragile plane 12, according to the implementation methods.
[0076] The principle of direct bonding, well known in the prior art, will not be described in detail here. Because it is based on molecular adhesion between assembled faces, a very good surface condition (cleanliness, low roughness, etc.) of the substrates 11,20 is required to obtain good assembly quality.
[0077] Prior to assembly, the donor substrate 11 and support 20 are usually prepared. For example, a typical sequence used in microelectronics, particularly for silicon-based substrates, includes ozone cleaning, SCI (“Standard Clean 1”) cleaning, and SC2 (“Standard Clean 2”) cleaning, with intervening rinses. The surfaces to be joined may also be activated, for example by plasma, before contacting them, to promote high bonding energy between the surfaces.
[0078] Optionally, the donor substrate 11 and / or the support substrate 20 may include an intermediate layer 50, at least on their respective front faces 1la,20a, to improve the bonding quality and energy of their interface, or for application requirements ([Fig. 2e], [Fig. 3e], [Fig. 4e], [Fig. 6e]). This intermediate layer may, in particular, be made of an insulating material, such as silicon oxide, silicon nitride, etc. In the specific case where the donor substrate 11 and the support substrate 20 are made of silicon, the structure 100 obtained at the end of the process is then a silicon-on-insulator (SOI) structure with buried cavities 30.
[0079] The intermediate layer 50, disposed on the donor substrate 11 and / or on the support substrate 20, can be formed by growth or deposition after one of the steps a) to d) of the process.
[0080] The direct bonding of step e) can be carried out under ambient atmosphere or under controlled atmosphere (for example, in a low pressure chamber).
[0081] The next step f) of the manufacturing process involves applying a heat treatment to the bonded structure 90 to induce spontaneous separation along the functional buried brittle plane 12, forming on the one hand the structure 100 and on the other hand the remainder of the donor substrate 11' ([Fig. 2f], [Fig. 3f], [Fig. 4f], [Fig. 6f]). The structure 100 comprises the thin layer 10, bonded to the support substrate 20, either directly or via an intermediate layer 50, along a bonding interface 40, and buried cavities 30.
[0082] As mentioned previously, the applicant identified that the quality of the transfer of the thin film 10 from the donor substrate 11 onto the support substrate 20 was improved by applying higher separation temperatures. Figure 5 shows... Images of a portion of the surface of several SOI structures with cavities (not according to the invention), after transfer, for different heat treatment temperatures between 350°C and 450°C (isothermal annealing). It is clear that the density of transfer defects (in black in the images) decreases with increasing heat treatment temperature in step f).
[0083] In the manufacturing process according to the invention, the functional buried fragile plane 12 is composed of two zones Z1, Z2 having distinct implantation characteristics, which allow to promote on the one hand a transfer kinetics compatible with "high" temperatures (in the regions benefiting from the stiffening effect), and on the other hand, the formation of large blisters at these temperatures with, possibly, a minimum of local exfoliation (in the regions above the cavities 30, not benefiting from the stiffening effect).
[0084] According to an example of implementation, it is the second zones Z2 of the functional buried fragile plane 12 which are directly above the cavities 30 in the bonded structure 90.
[0085] In the particular case of a targeted SOI-type structure 100 with cavities, the first light species can be hydrogen ions or atoms, and the second species helium ions or atoms. In practice, the donor substrate 11 is therefore made of monocrystalline silicon, the support substrate 20 is made of silicon, and an intermediate layer 50 of silicon oxide (for example, 200 nm thick) is disposed in whole or in part on one and / or the other of the front faces 11a,20a, before assembly. By way of example, the cavities 30 are made on the donor substrate 11, and have a depth of 100 nm, lateral dimensions of 40 µm and a spacing of 7 pm. The implantation energy of the first light species (hydrogen) is 140 keV, with a dose of 6E16 / cm2; the implantation energy of the second species (helium) is 220 keV, with a dose of 2E16 / cm2.
[0086] The first Zl zones of the functional buried fragile plane 12, which only contain hydrogen species, are directly above regions benefiting from a stiffening effect; the implantation characteristics in the first Zl zones are here favorable to a transfer in higher temperature ranges (typically greater than or equal to 450°C).
[0087] The second Z2 zones of the functional buried fragile plane 12, which include the first species (hydrogen) and the second species (helium), are directly above regions not benefiting from the stiffening effect (cavities 30); the implantation characteristics in the second Z2 zones are here favorable to the formation of large blisters, in the aforementioned "high" temperature ranges.
[0088] According to another implementation example, it is the first Zl zones of the functional buried fragile plane 12 that are arranged directly above the cavities 30 in the glued structure 90.
[0089] In the specific case of a targeted SOI-type structure 100 with cavities, the first light species can be hydrogen ions or atoms, or helium ions or atoms, or even hydrogen and helium ions or atoms (step c) would then consist of co-implantation, i.e., two successive implantations of these two light species). The second locally implanted species are ions or atoms capable of slowing down the growth kinetics of microcracks in the second Z2 zones of the functional buried brittle plane 12, compared to the growth kinetics of microcracks in the first Z1 zones. These second species can, for example, be silicon ions or atoms that will damage the donor substrate material 11 to a level more or less close to amorphization and thus modify the growth kinetics of the microcracks.Second species of a different nature could of course be introduced to achieve the same objective.
[0090] In practice, the donor substrate 11 is made of monocrystalline silicon, the support substrate 20 is made of silicon, and an intermediate layer 50 of silicon oxide (for example, 200 nm thick) is disposed on the front face 20a, prior to assembly. By way of example, the cavities 30 are made in the donor substrate 11 and have a depth of 100 nm, lateral dimensions of 40 µm, and a spacing of 7 pm. The implantation energy of the first light species (co-implanted hydrogen and helium) is 32 keV (H) and 52 keV (He), with respective doses of 1e¹⁶ / cm² and 1.5E¹⁶ / cm²; the implantation energy of the second species (Si) is 360 keV, with a dose of 10E¹⁴ / cm².
[0091] The first Zl zones of the functional buried fragile plane 12, which only contain the first hydrogen and helium species, are directly above regions not benefiting from a stiffening effect (cavities 30); the implantation characteristics in the first Zl zones are here favorable to the formation of large blisters with, possibly, limited local exfoliations, in the "high" temperature ranges desired for step f) of separation heat treatment.
[0092] The second Z2 zones of the functional buried fragile plane 12, which include the first species (hydrogen and helium) and the second species (Si), are directly above regions benefiting from the stiffening effect; the implantation characteristics in the second Z2 zones are here favorable to a transfer in the "high" temperature ranges (typically greater than or equal to 450°C).
[0093] Note that the manufacturing process may include, after step f), conventional finishing and / or smoothing steps (mechanical, mechano-chemical, chemical or thermal) of the free surface 10a of the thin film 10, in order to achieve the crystalline and surface quality required for said thin film 10 in the final structure 100.
[0094] According to a variant of the first embodiment of the invention, illustrated in Figures 6a to 6f, a step c') of localized implantation of third species at the front face 1a of the donor substrate 11 can be carried out. This step c') can, in particular, take place after step d) of cavity formation 30 in the donor substrate 11, and after removal of the mask M ([Fig. 6c]'). The third species are thus implanted in the first zones ZI of the functional buried fragile plane 12 and in another discontinuous buried plane 12” located at a distance and below the second zones Z2 of the functional buried fragile plane 12. These third species contribute to modifying the characteristics and properties of the first zones ZI of the functional buried fragile plane 12, but do not affect, or only slightly affect, those of the second zones Z2.
[0095] Following the transfer of the thin layer 10, the discontinuous buried plane 12” is found in the rest of the donor substrate 11' ([Fig.6f]).
[0096] The present invention can be used for a wide range of MEMS or NEMS (“Nanoelectromechanical Systems”) devices, or for any other application taking advantage of a thin film 10 disposed locally on a cavity 30, within a structure 100. As already mentioned in this description, a SOI (Silicon on Insulation) substrate with buried cavities is a known example of such a structure 100.
[0097] The invention is not limited to the embodiments described and alternative embodiments may be made without departing from the scope of the invention as defined by the claims.
Claims
Claims
1. A method of manufacturing a structure (100) comprising a plurality of cavities (30) confined between a thin layer (10) and a support substrate (20), the manufacturing method comprising the following steps: a) providing a donor substrate (11) and a support substrate (20), each of the substrates (11, 20) having a front face (11a, 20a) and a rear face (11b, 20b); b) implanting first light species in the donor substrate (11), to form a uniform buried fragile plane (12') delimiting with the front face (11a) of the donor substrate (11), the thin layer (10) to be transferred;c) the localized implantation of second species in the donor substrate (11) so as to introduce said second species into the uniform buried fragile plane (12') only at the level of second zones (Z2), to form a functional buried fragile plane (12) having: - first zones (Z1) comprising the first light species and not the second species, and - the second zones (Z2), comprising the first light species and the second species; d) the formation of a plurality of cavities (30) opening at the level of a front face (11a, 20a) of the donor substrate (11) or of the support substrate (20); e) assembly by direct bonding of the donor substrate (11) onto the support substrate (20), at their respective front faces (11a, 20a), to form a bonded structure (90) in which the cavities (30) are located directly above either the first zones (Z1) or the second zones (Z2) of the functional buried fragile plane (12);f) applying a heat treatment to the bonded structure (90) to cause spontaneous separation along the functional buried fragile plane (12) and form on the one hand the structure (100) and on the other hand the remainder of the donor substrate (11').;
2. Manufacturing method according to claim 1, in which the implantation of step c) is carried out in the presence of a mask (M), arranged on the front face (11a) of the donor substrate (11), directly above the first zones (Z1) of the functional buried fragile plane (12).
3. A manufacturing method according to claim 2, wherein the formation cavities (30) in step d) is carried out by local etching of the front face (20a) of the support substrate (20), for example by means of a mask (M') arranged on said front face (20a).
4. Manufacturing method according to claim 2, in which, after step c), step d) of forming the cavities (30) comprises etching the front face (11a) of the donor substrate (11), directly above the second zones (Z2), the first zones (Z1) being protected from etching by the mask (M).
5. Manufacturing method according to claim 4, comprising, after step d) and after removal of the mask (M), a step c') of localized implantation of third species at the level of the front face (11a) of the donor substrate (11), the third species thus being implanted in the first zones (Z1) of the functional buried fragile plane (12) and in another buried plane (12”) located at a distance from and under the second zones (Z2) of the functional buried fragile plane (12).
6. Manufacturing method according to claim 1, in which step d) of forming the cavities (30) is carried out before step c), and comprises: - the application of a mask (M) arranged on the front face (11a) of the donor substrate (11), in line with the second zones (Z2) of the functional buried fragile plane (12) intended to be formed in the subsequent step c), and - the etching of the front face (11a) of the donor substrate (11), in line with the first zones (Z1), the second zones (Z2) being protected from etching by the mask (M).
7. Manufacturing method according to claim 6, wherein after step d) and after removal of the mask (M) from the front face (11a) of the donor substrate (11), step c) of implantation is carried out, the second species thus being implanted in the second zones of the functional buried fragile plane (12) and in another buried plane (12”) located at a distance from and under the first zones (Zl) of the functional buried fragile plane (12).
8. Manufacturing method according to one of claims 1 to 5, in which: - the second zones (Z2) of the functional buried fragile plane (12) are directly above the cavities (30), in the bonded structure (90), and - the first light species are hydrogen ions or atoms, and the second species are helium ions or atoms.
9. Manufacturing method according to one of claims 1, 2, 3, 6 and 7, in which: - the first zones (Zl) of the functional buried fragile plane (12) are directly above the cavities (30) in the bonded structure (90), - the first light species are hydrogen ions or atoms, or helium ions or atoms, or hydrogen and helium ions or atoms, and - the second species are silicon ions or atoms, capable of slowing down the growth kinetics of microcracks in the second zones (Z2) of the functional buried fragile plane (12), compared to the growth kinetics of microcracks in the first zones (Zl).
10. Manufacturing method according to one of claims 1 to 9, in which the assembly step e) involves at least one intermediate layer (50) arranged on the donor substrate (11) and / or on the support substrate (20), said intermediate layer (50) having been deposited after one of steps a) to d).