Removable structures for transferring or handling layers and methods of using the removable structures to transfer layers

Abstract

The invention relates to a removable structure (100) comprising: - at least two interfaces, an assembly interface (30) and a preferential separation interface (1), - a recipient substrate (20), - a donor substrate (10) comprising a useful layer (3) to be transferred, the useful layer being arranged on an initial substrate (2), the preferential separation interface (1) being located between the useful layer (3) and the initial substrate (2) and the assembly interface (30) being located between the useful layer (3) and the recipient substrate (20). The removable structure (100) is characterized in that the assembly interface (30) has an assembly interruption zone (31) comprising at least one cavity (31a) present in the recipient substrate (20) or in the useful layer (3), the assembly interruption zone (31) being located in a peripheral region of the removable structure (100).

Description

Technical Field

[0001] This invention relates to the field of transfer thin layers for applications in microelectronics, optics, microsystems, etc. In particular, this invention relates to detachable structures that can be used to transfer or handle thin layers. Background Technology

[0002] Many applications (particularly in the fields of microelectronics, optics, or microsystems) require thin layers (possibly containing components) to be disposed on specific substrates (thin, flexible, metallic, insulating, etc.). These specific substrates are not always compatible with the processes used to manufacture the thin layers and / or the processes used to add components to said layers.

[0003] Therefore, it is advantageous to be able to transfer thin layers (with or without components) from an initial substrate compatible with the processes mentioned above to a specific target substrate that has the characteristics required for the target application.

[0004] There are several processes that transfer a thin layer formed on an initial substrate to a target substrate.

[0005] Some transfer processes involve attaching a thin layer (set on an initial substrate) to a target substrate, followed by mechanical and / or chemical removal of the initial substrate, thereby transferring the thin layer to the target substrate. The main disadvantages of this approach are the cost associated with the loss of the initial substrate and the limited mechanical and chemical treatments that can negatively impact the quality of the thin layer during transfer.

[0006] Other processes are based on separating the thin layer from the initial substrate by subjecting the layer or weakened interface present between the thin layer and the initial substrate to mechanical stress or by applying chemical treatment to it; during the separation operation, the thin layer, which has been pre-attached to the target substrate, is transferred to the target substrate. This is particularly true of the processes described in documents FR2748851, FR2823599, or FR2823596; the detachable structure is typically described as having a layer or weakened interface, wherein separation can be performed in such a way that the thin surface layer is released and transferred to the target substrate.

[0007] One challenge associated with these methods is that, due to the potential difficulty in precisely targeting mechanical stress and / or chemical etching to the weakened interface or layer, separation can sometimes occur at interfaces or layers other than the weakened interface or layer. Variations in the geometry of the substrate edges, the methods used to apply mechanical stress, or the chemical etching solutions used for separation can cause separation to begin at interfaces other than the weakened interface, even if those other interfaces have superior mechanical integrity.

[0008] To address this problem, it has been proposed to locally, particularly at the edges of the substrate, enhance the mechanical integrity of interfaces other than the weakened interface and / or further reduce the integrity of the weakened interface. However, these measures are not always able to prevent separation from initiating at unintended interfaces.

[0009] Document FR2995446 relates to a detachable structure comprising at least two interfaces, including a weakened interface where separation is expected to occur. This document provides a solution for redirecting the separation front toward the weakened interface when separation begins at other interfaces.

[0010] The subject of this invention

[0011] This invention encompasses an alternative solution that facilitates locating separation within a weakened interface of a detachable structure. One subject of this invention is providing a detachable structure comprising at least two interfaces, one of which is a weakened interface or a facilitated-detachment interface. The detachable structure is used for transferring or transporting layers. Summary of the Invention

[0012] This invention relates to a detachable structure for transferring or transporting layers, the detachable structure comprising:

[0013] - At least two interfaces: an assembly interface and a disassembly interface.

[0014] -Receptor substrate,

[0015] - A donor substrate comprising a working layer to be transferred, the working layer being disposed on an initial substrate, an advantageous disassembly interface being located between the working layer and the initial substrate, and an assembly interface being located between the working layer and the acceptor substrate.

[0016] The distinctive feature of the detachable structure is that the assembly interface has an assembly interruption region comprising at least one cavity present in the acceptor substrate or the working layer, wherein, if the at least one cavity is present in the working layer, the depth of the cavity is strictly less than the thickness of the working layer. The assembly interruption region is located in the peripheral region of the detachable structure and allows modification of the stress field at the head of the wavefront of the separation wave when a separation wave is induced in the assembly interface for the purpose of transferring or transporting the working layer.

[0017] Modification of the stress field by assembling at least one cavity in the interrupted region allows the separation wave to deflect from the assembly interface toward a favorable disassembly interface, thereby allowing the working layer to be moved onto the acceptor substrate.

[0018] Advantageous features according to the invention may be adopted individually or in any feasible combination:

[0019] • The assembly interruption zone extends along the periphery of the detachable structure for a length of less than or equal to 20 mm;

[0020] • The assembly interruption area is located less than 10mm from the edge of the detachable structure;

[0021] • The cavity (at least one) has a lateral dimension between a few micrometers and a few millimeters, preferably between 20 micrometers and 1 mm;

[0022] • The depth of the cavity (at least one) is between 0.5 micrometers and tens of micrometers (typically 50 micrometers);

[0023] • The cavity (at least one) has a square, rectangular, triangular, trapezoidal or circular perimeter in a plane parallel to the assembly interface.

[0024] • At least one straight segment of the periphery of the cavity is parallel to the detachable edge of the detachable structure or parallel to the tangent of the detachable edge of the detachable structure.

[0025] • The straight segment of the periphery of the cavity having the largest lateral dimension is parallel to the disassembly edge of the detachable structure or parallel to the tangent of the disassembly edge of the detachable structure.

[0026] • The assembly interruption region includes multiple cavities spaced between 1 micrometer and 1 millimeter, typically between a few micrometers and several hundred micrometers.

[0027] • The percentage of contact area between cavities in the assembly interruption zone is less than 80%, or even less than 50%;

[0028] • The cavity is aligned along a straight line or along a curve, the convexity of which points to the center of the detachable structure;

[0029] • The assembly interruption area is located less than 8 mm, or even less than 3 mm, from the edge of the detachable structure;

[0030] • The thickness of the working layer ranges from several hundred nanometers to several hundred micrometers, typically between 200 nm and 200 micrometers;

[0031] • The advantageous disassembly interface has a first interfacial surface energy, the assembly interface has a second interfacial surface energy, and the difference in interfacial surface energy between the advantageous disassembly interface and the assembly interface is greater than or equal to 1000 mJ / m 2 ;

[0032] • The advantageous disassembly interface is a molecular adhesion interface with a first binding energy, and the assembly interface is a molecular adhesion interface with a second binding energy, wherein the first binding energy is less than the second binding energy.

[0033] • The difference in binding energy between the advantageous disassembly interface and the assembly interface should be at least approximately 1000 mJ / m 2 .

[0034] The present invention also relates to a method for transferring a working layer from a donor substrate to a acceptor substrate, the method comprising the following steps:

[0035] a) Provide a detachable structure as described above.

[0036] b) Apply mechanical stress to the disassembly edge of the detachable structure, the disassembly edge being located as close as possible to the assembly interruption area, and the mechanical stress being able to induce a separation wave at the assembly interface or at a favorable disassembly interface.

[0037] c) If the separation wave is initiated at the assembly interface, then when the separation wave passes through the assembly interruption region, it is deflected into a favorable disassembly interface.

[0038] d) Propagate separation waves at favorable disassembly interfaces to result in complete separation of the disassembleable structure.

[0039] Advantageous features according to the invention may be adopted individually or in any feasible combination:

[0040] Mechanical stress is applied in such a way that the propagation direction of the separation wave is perpendicular to at least one straight segment of the periphery of (at least one) cavity in the assembly interruption zone.

[0041] Mechanical stress is applied in such a way that the propagation direction of the separation wave is perpendicular to the straight segment with the largest lateral dimension of the periphery of (at least one) cavity.

[0042] Mechanical stress is applied by inserting a bevel-edged tool between the edges of the acceptor substrate and the donor substrate.

[0043] Step a) includes:

[0044] A donor substrate is provided comprising a working layer disposed on an initial substrate, with an advantageous disassembly interface located between the working layer and the initial substrate.

[0045] Provides a receptor substrate,

[0046] In the peripheral region of the acceptor substrate or the working layer, at least one cavity is created with an opening to the assembly surface belonging to the acceptor substrate or the assembly surface belonging to the working layer.

[0047] The working layer and the acceptor substrate are assembled at their respective surfaces to be assembled. Attached Figure Description

[0048] Referring to the accompanying drawings and the following detailed description, other features and advantages of the invention will become apparent, wherein:

[0049] - Figure 1a and Figure 1b Cross-sectional views and plan views of the detachable structure according to the invention are depicted respectively; in the plan views, the cavities are made visible to better understand the distribution and location of the cavities, although they should be hidden because they are located between the working layer and the acceptor substrate.

[0050] - Figure 2a , Figure 2b as well as Figure 2c Cross-sectional views and two plan views of the detachable structure according to the invention are depicted respectively; in the plan views, the cavities are made visible to better understand the distribution and location of the cavities, although they should be hidden because they are located between the working layer and the acceptor substrate.

[0051] - Figures 3a to 3g The steps of the transfer method according to the present invention are shown;

[0052] - Figure 4a A plan view of a detachable structure is depicted during the process of applying mechanical stress, which is a step in the transfer method according to the invention. Figure 4b A magnified photograph depicting the working layer moving onto the acceptor substrate at the end of the transfer method according to the invention, in and around the assembly interruption region. Detailed Implementation

[0053] In the description section, the same labels as in the diagram can be used for elements of the same nature.

[0054] The accompanying diagram is illustrative and is not drawn to scale for ease of reading. In particular, the layer thickness along the z-axis is not proportional to the lateral dimensions along the x- and y-axis.

[0055] This invention relates to a detachable structure 100, which includes at least two interfaces: an assembly interface 30 and a detachable interface 1. Figure 1a In the diagram, the two interfaces extend in a plane parallel to the plane (x, y).

[0056] A detachable structure refers to a structure 100 that is designed to be mechanically pressurized to induce a desired separation at a favorable detachment interface 1; due to the presence of a second interface (assembly interface 30), the separation wave propagates simultaneously in both interfaces 1 and 30.

[0057] The detachable structure 100 includes a donor substrate 10, which includes a working layer 3 to be transferred, which is disposed on an initial substrate 2; an advantageous detachment interface 1 is located between the working layer 3 and the initial substrate 2.

[0058] For example, the working layer 3 can be formed of semiconductor materials (such as silicon, silicon carbide, germanium, III-V compounds, etc.) and / or insulating materials (especially piezoelectric materials) (such as lithium tantalate or lithium niobate). Of course, this list is not exhaustive, and any material in the form of a thin layer that may be desired to be transferred from the donor substrate 10 to the acceptor substrate 20 can constitute the working layer 3.

[0059] The working layer 3 may also include multiple films of different materials, and / or functional structures (e.g., cavities), particularly on its face 30 facing the acceptor structure, and / or may include microelectronic components wholly or partially. Naturally, it is desirable that the adhesion between the stacks of various films or components is stronger than the integrity of the advantageous separation interface 1, the characteristics of which will be described in detail later. Typically, the characteristics of the working layer 3 depend on the intended application and the required functionality.

[0060] The thickness of the working layer 3 is between several hundred nanometers and several hundred micrometers, for example, between 200 nanometers and 200 micrometers, or preferably between 1 micrometer and 50 micrometers.

[0061] The initial substrate 2 is advantageously formed from a low-cost material that provides good mechanical support for the transport working layer 3. Although other materials are conceivable, silicon is typically the material of choice due to its compatibility with any microelectronics production line.

[0062] The initial substrate 2 can, for example, be in the form of a wafer having a diameter of 100 mm to 450 mm and a thickness between 250 micrometers and 850 micrometers. Of course, the initial substrate 2 can also be alternatively in other forms (e.g., square).

[0063] The detachable structure 100 also includes a recipient substrate 20 assembled on the donor substrate 10: the assembly interface 30 is located between the recipient substrate 20 and the working layer 3.

[0064] The acceptor substrate 20 may be made of insulating, semiconductor, or conductive materials and may be solid or comprise multiple layers or functional surface structures (e.g., cavities), or may comprise active or passive elements wholly or partially. The characteristics of the acceptor substrate 20 depend primarily on the intended application and desired functionality.

[0065] Similar to the initial substrate 2, the acceptor substrate 20 may, for example, take the form of a wafer having a diameter of 100 mm to 450 mm and a thickness between 250 micrometers and 850 micrometers.

[0066] The detachable structure 100 according to the invention is intended to be separated at a favorable detachment interface 1 so that the working layer 3 can be transferred from the donor substrate 10 to the acceptor substrate 20.

[0067] Typically, the mechanical integrity of the detachable interface 1 is therefore worse, or even much worse, than that of the assembled interface 30, as is often the case in detachable structures comprising two interfaces. Preferably, the objective is to achieve a mechanical integrity or interfacial surface energy of at least approximately 1000 mJ / m² between the two interfaces 1 and 30. 2 The differences.

[0068] According to an advantageous embodiment, the advantageous disassembly interface 1 is a bonding interface using molecular adhesion with a first binding energy E1. The assembly interface 30 can be a direct bonding interface using molecular adhesion, thermoforming, or some other technique with a second binding energy E2, where the first binding energy E1 is less than the second binding energy E2.

[0069] As is well known, the difference between the first binding energy E1 and the second binding energy E2 can be obtained by managing the surface roughness of the surfaces to be bonded, the materials used to achieve molecular adhesion bonding, and chemical treatments (wet cleaning or plasma activation) applied to the surfaces prior to bonding. Materials such as silicon oxide and silicon nitride can be deposited on the surfaces to be bonded (to form a favorable separation interface 1 or assembly interface 30), and these materials can be treated in a manner that adjusts the surface energy of the resulting interface for molecular adhesion bonding (cleaning, polishing, plasma activation, etching, etc.).

[0070] Advantageously, as previously stated, the binding energy difference (E2-E1) between the two interfaces 1 and 30 is chosen to be at least about 1000 mJ / m 2 For example, the first binding energy E1 can be approximately 2000 mJ / m. 2 The second binding energy E2 can be greater than 3000 mJ / m 2 It is well known that the binding energy can be specifically evaluated using Maszara blade measurement technology.

[0071] A distinctive feature of the detachable structure 100 according to the invention is that the assembly interface 30 has an assembly interruption region 31, which includes at least one cavity 31a present in the acceptor substrate 20 or the working layer 3. The assembly interruption region 31 corresponds to a region where the assembly interface is interrupted, i.e., where there is no contact between the acceptor substrate 20 and the working layer 3.

[0072] The assembly interruption area 31 is located in the peripheral area of ​​the detachable structure 100. Preferably, the assembly interruption area 31 is located less than 10 mm from the edge 100a of the structure 100. Advantageously, the assembly interruption area 31 is located less than 8 mm, or even less than 5 mm, or even less than 3 mm from the edge 100a of the detachable structure.

[0073] For a detachable structure 100 formed from two wafers 10, 20 assembling a microelectronic level, it is common to have an unbonded peripheral exclusion region 100b, which is connected to the edge geometry (bevel) of the wafer or to the edge geometry of the working layer 3 present on one of the two wafers; this exclusion region 100b rarely exceeds 1 mm to 2 mm. In the presence of this exclusion region 100b, an assembly interruption region 31 is radially offset relative to the exclusion region 100b toward the interior of the detachable structure 100 because, by definition, it needs to interrupt the assembly interface 30 that contacts the acceptor substrate 20 with the working layer 3. For example, the assembly interruption region can be located 0.5 mm, 1 mm, or 2 mm from the exclusion region 100b.

[0074] Advantageously, the assembly interruption region 31 is highly localized, meaning that it does not extend along the entire periphery of the detachable structure 100 in the peripheral region, but only within a length of a few hundred micrometers (typically 200 micrometers) to tens of millimeters (typically 50 mm to 100 mm), for example, between 1 mm and 20 mm, preferably between 5 mm and 15 mm. This provides the advantage of limiting its impact on the available surface area of ​​the working layer 3.

[0075] As previously mentioned, the assembly interruption region 31 includes regions formed on the acceptor substrate 20 (e.g., Figure 1a As illustrated) in or working layer 3 (e.g. Figure 2a At least one cavity 31a in the illustrated. It should be noted that when at least one cavity 31a is formed in the working layer 3, the depth of the cavity may vary, for example, between 5% and 95% of the thickness of the working layer 3, and this depth will certainly never exceed the thickness of the layer 3.

[0076] Advantageously, the assembly interruption region 31 includes multiple cavities 31a.

[0077] Cavities 31a can be spaced apart, for example, at a distance between 1 micrometer and 1 mm, typically between a few micrometers and several hundred micrometers, for example, 500 micrometers. These cavities can be aligned in a straight line or along a curved line in a plane (x, y) parallel to the assembly interface 30. The straight line is preferably parallel to the edge 100a of the detachable structure 100 or parallel to the tangent T of the edge 100a. Figure 1b and Figure 2c The curve may have a convex curvature toward the center of the detachable structure 100; in other words, as in Figure 2b As can be seen in the example, the curve follows a curvature opposite to that of the edge 100a of the detachable structure 100.

[0078] Cavity 31a will be referred to below. It should be understood that the listed features can be applied to all cavities 31a that constitute assembly interruption region 31, if the assembly interruption region includes multiple cavities.

[0079] Advantageously, the cavity 31a has a lateral dimension between a few micrometers and a few millimeters, typically between 20 micrometers and 1 mm. Moreover, the depth of the cavity can be between 0.5 micrometers and tens of micrometers (typically reaching 20 micrometers, 50 micrometers) or even up to 100 micrometers; for example, the cavity 31a can have a depth of 3 micrometers.

[0080] When the assembly interruption region 31 includes multiple cavities 31a, the percentage of the contact area between the acceptor substrate 20 and the working layer 3 (i.e., the percentage of the contact area between the cavities 31a in the assembly interruption region 31) is preferably less than 80%, or even less than 50%.

[0081] The cavity 31a of the assembly interruption zone 31 may have a square, rectangular, triangular, trapezoidal or circular perimeter in a plane (x, y) parallel to the assembly interface 30.

[0082] Preferably, at least one straight segment around the cavity 31a is parallel to the detachable edge 100a' of the detachable structure 100 or parallel to the tangent T of the detachable edge 100a' of the detachable structure 100.

[0083] According to another preferred aspect, the straight line segment with the largest lateral dimension around the cavity 31a is parallel to the detachable edge 100a' of the detachable structure 100 or parallel to the tangent T of the detachable edge 100a' of the detachable structure 100. For example, in the case where the cavity is rectangular, the longer side of the cavity 31a in the plane (x, y) will extend parallel to the tangent T.

[0084] Furthermore, when the shape of cavity 31a is asymmetrical, there exists a preferred orientation for the pattern of cavity 31a relative to the split edge 100a' (or its tangent T), or more specifically, relative to the propagation direction of the separating wave, as will be described with reference to the transfer method according to the invention. It appears more advantageous that the separating wave ultimately passes through the segment with the largest dimension. Figure 2c In the example, if the cavity 31a in the assembly interruption zone 31 has a triangular periphery, then it is therefore advantageous for these cavities to be positioned such that the vertices of the triangles point toward the disassembly edge 100a'.

[0085] The present invention also relates to a method for transferring the working layer 3 from the donor substrate 10 to the acceptor substrate 20.

[0086] The method first includes step a) providing a detachable structure 100 as described above.

[0087] According to one implementation, step a) includes the following sub-steps a1) to a4).

[0088] First, step a1) involves providing a donor substrate 10 comprising a working layer 3 disposed on an initial substrate 2, with an advantageous separation interface 1 located between the working layer 3 and the initial substrate 2. Figure 3a ).

[0089] The working layer 3 of the donor substrate 10 can be fabricated using any known layer transfer technique, such as:

[0090] - After bonding, mechanical / chemical thinning based on grinding, polishing, chemical etching and cleaning techniques is performed; in this case, working layer 3 originates from the working substrate that was bonded to the initial substrate and then thinned.

[0091] -Use Smart The method involves transferring thin layers that are typically less than 2 micrometers thick; in this case, the working layer 3 also originates from a working substrate implanted with a lighter material, which is bonded to the initial substrate and then separated along the buried fragile plane defined by the implantation.

[0092] -Use Smart The method is followed by an epitaxial growth or deposition step aimed at thickening the transferred working layer.

[0093] The bonding mentioned in these different techniques results in the creation of a favorable separation interface 1. Therefore, it is necessary to adjust the bonding parameters (contact materials, roughness of the surfaces to be bonded, cleaning operations and chemical activation treatments of the surfaces to be bonded, etc.) to obtain a first bonding energy (or first interface surface energy) E1 within the desired range after the donor substrate 10 may undergo heat treatment. This is especially true when the working layer 3 is deposited before being transferred onto the acceptor substrate 20, and / or when a functional structure is formed, and / or when all or some of the elements are created on or in the working layer 3.

[0094] Preferably, the first binding energy (or the first interfacial surface energy) E1 is between 1000 mJ / m 2 Up to 3000mJ / m 2 Between. As previously mentioned, advantageously, the aim is to achieve 1000 mJ / m² at least between the advantageous disassembly interface 1 (energy E1) and the assembly interface 30. 2 The energy difference will be used to form the assembly interface 30 in the subsequent step a4) of the method.

[0095] Step a2) of the method involves providing a receptor substrate 20, the characteristics of which depend on the intended application and desired function, as previously mentioned. Figure 3b ).

[0096] The next step a3) involves forming an opening in the peripheral region of the acceptor substrate 20 or the working layer 3 to the assembly surface 20c belonging to the acceptor substrate 20. Figure 3c (i) on, or open to the assembly surface 3c belonging to working layer 3. Figure 3c One or more cavities 31a on (ii) of the donor substrate 10. When assembling the donor substrate 10 onto the acceptor substrate 20, the cavity 31a will enable the creation of an assembly interruption region 31.

[0097] The assembly interruption region 31 is located less than 10 mm from the edge of the peripheral region of the donor substrate 10 or the acceptor substrate 20. Advantageously, the assembly interruption region 31 is even located less than 8 mm, less than 5 mm, or even less than 3 mm from the edge of the substrate.

[0098] The assembly interruption region 31 is preferably highly localized, that is, it does not extend along the entire periphery of the donor substrate 10 or the acceptor substrate 20 in the peripheral region, but only within a length of a few hundred micrometers to tens of millimeters.

[0099] Cavities 31a can be implemented using conventional photolithography and etching techniques. As previously mentioned, each cavity 31a preferably has a lateral dimension between a few micrometers and a few millimeters, a depth between 0.5 micrometers and tens of micrometers, and a shape that varies in a plane (x, y).

[0100] Finally, step a4) includes assembling the working layer 3 and the acceptor substrate 20 at their respective assembly surfaces 3c, 20c to form a detachable structure 100. Figure 3d (i) and (ii)).

[0101] As is well known, the assembly of these two substrates can be performed by direct bonding using molecular adhesion, by metal bonding, or by adhesive bonding, depending on the intended application and the compatibility of the bonding technology.

[0102] Step a4) may involve cleaning, deposition of an adhesion-promoting layer, surface activation, or other surface preparation procedures before bringing the substrates 10 and 20 into contact. Step a4) may involve, after the substrates 10 and 20 have come into contact, performing heat treatment at a higher or lower temperature, depending on the type of bonding and the properties of the materials constituting the assembled substrates 10 and 20, to solidify the assembly interface 30.

[0103] At the end of step a4), the binding energy E2 of the assembled interface 30 is greater than the binding energy E1 of the interface 1 that facilitates disassembly. Specifically, the difference between the binding energy E2 and the binding energy E1 is approximately 1000 mJ / m². 2 Even higher.

[0104] At the end of step a), having just described one particular embodiment, the method according to the invention includes step b), which involves applying mechanical stress to the detachable edge 100a' of the detachable structure 100. Figure 3e (i) and (ii)).

[0105] The separation edge 100a' is positioned as close as possible to the assembly interruption region 31, and mechanical stress can induce a separation wave in the assembly interface 30 or in the advantageous separation interface 1. For example, mechanical stress can be applied by inserting a bevel-edge 40 between the edges of both the assembled donor substrate 10 and the acceptor substrate 20. Alternatively, this mechanical stress can be applied by injecting a liquid or gaseous fluid between these edges, or by any other suitable technique.

[0106] Typically, the direction of the propagating wave lies in the plane (x, y) and is perpendicular to the split edge 100a' or the tangent T perpendicular to the split edge 100a'.

[0107] As previously mentioned, due to the edge geometry of the donor substrate 10 and the acceptor substrate 20, it is common for the detachable structure 100 to have a peripheral exclusion region. It should be noted that, for simplicity, in Figures 3a to 3g The exclusion zone is not depicted in the text.

[0108] When mechanical stress is applied (e.g., by inserting the beveled blade 40), a separation wave 41 can initiate at the assembly interface 30, regardless of the lower mechanical integrity of the interface 1 that facilitates disassembly. This initiation of the separation wave 41 in the assembly interface 30 is particularly facilitated by the presence of an exclusion zone that provides direct access to the interface 30.

[0109] For this reason, the method according to the invention then proceeds to step c), during which, if the separation wave 41 has already been triggered at the assembly interface 30, then when the separation wave 41 passes through the assembly interruption region 31, the separation wave deflects into the advantageous disassembly interface 1. Figure 3f (i) and (ii)). Effectively, the cavity 31a of the assembly interruption region 31 allows modification of the stress field at the head of the wavefront of the separation wave 41, thereby causing the separation wave to deflect toward the lowest energy interface, in this example toward the favorable disassembly interface 1.

[0110] Advantageously, the mechanical stress is applied in such a manner that the propagation direction of the separation wave 41 (parallel to the axis y in the figure) is perpendicular to at least one straight segment of the periphery of the cavity (or multiple cavities) 31a in the assembly interruption zone 31. Figure 4a ).

[0111] According to another advantageous embodiment, the mechanical stress is applied in such a way that the propagation direction of the separation wave 41 is perpendicular to the straight line segment with the largest lateral dimension around the periphery of the cavity 31a. This scenario may occur, for example, when the cavity (or multiple cavities) 31a has a rectangular shape. The longest dimension (length) of the rectangle is preferably oriented in such a way that it is perpendicular to the propagation direction of the separation wave 41.

[0112] As previously mentioned, when cavity 31a is triangular, it is also advantageous for the vertices of the triangle to point towards the splitting edge 100a'; in other words, preferably, the separation wave induced at the splitting edge 100a' ultimately passes through the base of the triangle. Figure 4a ).

[0113] It should be noted that when the separation wave 41 is directly induced in the advantageous disassembly interface 1 in step b), the wave does not modify its position as it passes through the assembly interruption zone 31: after passing through the interruption zone 31, the separation wave 41 continues to propagate along the advantageous disassembly interface 1.

[0114] The transfer method then includes step d): propagating a separation wave at the favorable disassembly interface 1 to result in the complete separation of the disassembleable structure 100. Figure 3g (i) and Figure 3g (ii)).

[0115] Once the separation wave 41 has been deflected into the correct interface, it readily propagates along the advantageous separation interface 1 with lower mechanical integrity, either spontaneously (if the mechanical stress applied to induce the separation wave 41 is sufficient to cause the separation wave to propagate), or by means of continuously held or intermittently applied mechanical stress.

[0116] Figure 4b A top view photograph is shown showing the transfer of the working layer 3 (made of silicon) from the detachable structure 100 according to the invention onto the acceptor substrate 20 (made of silicon). Specifically, the photograph is magnified around the assembly interruption region 31 formed in the acceptor substrate 20. The deflection of the separation wave between the assembly interface 30 (a direct bond of oxide SiO2 / silicon type) upstream of the assembly interruption region 31 and the favorable disassembly interface (a direct bond of SiO2 / SiO2 type) downstream of the assembly interruption region 31 can be seen. Downstream of the cavity 31a, the working layer 3 is transferred onto the acceptor substrate 20. Figure 4b In the example, the eight cavities 31a forming the assembly interruption region 31 are square in shape, with a lateral dimension of 500 μm × 500 μm and a depth of 3 μm. They are located approximately 3 mm from the edge.

[0117] The transfer method applied to the detachable structure 100 according to the invention allows the separation wave 41 to be effectively deflected from the assembly interface 30 of the detachable structure 100 toward a favorable disassembly interface. Therefore, the surface area of ​​the working layer 3 transferred onto the acceptor substrate 20 can be maximized, and a high-quality working layer 3 can be transferred.

[0118] Of course, the present invention is not limited to the described embodiments, and variations in implementation may be applied without departing from the scope of the invention as defined by the claims.

[0119] Although the preferred embodiment of the detachable structure 100 describes an advantageous detachable interface 1 based on direct bonding using molecular adhesion, the invention is equally applicable to other types of interfaces.

[0120] For example, the advantageous separation interface 1 can be formed by embedding a vulnerable plane, which is obtained by implanting a light material, forming a porous material layer (e.g., porous silicon), or forming a multilayer deposition (where one interface has low energy (for example, as described in application FR3082997)). Regarding this last option, for example, the multilayer can involve silicon oxide or silicon nitride layers on noble metal (Au, Pt, Ag, etc.) layers, with the interfaces between these layers having low interfacial surface energy.

[0121] Generally speaking, as long as the detachable structure 100 includes two interfaces 1 and 30, and these two interfaces exhibit a sufficient difference in surface energy, especially greater than or equal to 1000 mJ / m2 This method can be applied to the energy difference.

Claims

1. A detachable structure (100) used for transferring or handling a layer, said detachable structure comprising: - at least two interfaces, namely an assembly interface (30) and a favorable detachment interface (1), - a recipient substrate (20), - a donor substrate (10) comprising a working layer (3) to be transferred, said working layer being disposed on an initial substrate (2), said favorable detachment interface (1) being located between the working layer (3) and the initial substrate (2) and said assembly interface (30) being located between the working layer (3) and the recipient substrate (20), said detachable structure (100) being characterized in that: - the assembly interface (30) has an assembly interruption zone (31) comprising at least one cavity (31a) present in the recipient substrate (20) or in the working layer (3), in the case where the at least one cavity is present in the working layer, the depth of the cavity (31a) being strictly less than the thickness of the working layer (3), - the assembly interruption zone (31) is located in a peripheral region of the detachable structure (100) and does not extend along the entire perimeter of the detachable structure (100), said assembly interruption zone (31) allowing to modify the stress field at the head of the wave front of a separation wave (41) when this separation wave is initiated in the assembly interface (30) for the purpose of transferring or handling the working layer (3).

2. The demountable structure (100) according to claim 1, wherein The assembly interruption zone (31) is located less than 10 mm from the edge of the detachable structure (100).

3. Demountable structure (100) according to claim 1 or 2, wherein The assembly interruption zone extends over a length less than or equal to 20 mm along the perimeter of the detachable structure.

4. The detachable structure (100) according to claim 1 or 2, wherein The depth of the at least one cavity (31a) is between 0.5 microns and 50 microns.

5. The detachable structure (100) according to claim 1 or 2, wherein The at least one cavity (31a) has a rectangular, triangular, trapezoidal or circular perimeter in a plane parallel to the assembly interface.

6. The demountable structure (100) according to claim 5, wherein At least one straight segment of the perimeter of the at least one cavity (31a) is parallel to the detachment edge (100a') of the detachable structure (100) or to a tangent (T) to the detachment edge (100a') of the detachable structure (100).

7. The demountable structure (100) according to claim 5, wherein The straight segment of the perimeter of the at least one cavity (31a) having the largest transverse dimension is parallel to the detachment edge (100a') of the detachable structure (100) or to a tangent (T) to the detachment edge (100a') of the detachable structure (100).

8. The dismountable structure (100) according to claim 1 or 2, wherein The assembly interruption zone (31) comprises a plurality of cavities (31a) and is spaced apart by a distance between 1 micron and 1 mm.

9. The demountable structure (100) according to claim 8, wherein The percentage of contact area between the cavities (31a) of the assembly interruption zone (31) is less than 80%, or less than 50%.

10. The demountable structure (100) according to claim 8, wherein The cavities (31a) are aligned along a straight line or are aligned along a curve, the convexity of which is directed towards the center of the detachable structure (100).

11. Demountable structure (100) according to claim 1 or 2, wherein The assembly interruption zone (31) is located less than 8 mm, or less than 3 mm, from the edge of the detachable structure (100).

12. The dismountable structure (100) according to claim 1 or 2, wherein The thickness of the working layer (3) is between 200 nm and 200 microns.

13. Detachable structure (100) according to claim 1 or 2, wherein: - said favorable detaching interface (1) has a first interface surface energy, - said assembly interface (30) has a second interface surface energy, - the difference in interfacial surface energy between the favorable detachment interface (1) and the assembly interface (30) is greater than or equal to 1000 mJ / m 2 .

14. The dismountable structure (100) according to claim 1 or 2, wherein said favorable detaching interface (1) is a bonding interface using molecular adhesion with a first bonding energy, and said assembly interface (30) is a bonding interface using molecular adhesion with a second bonding energy, said first bonding energy being lower than said second bonding energy.

15. The demountable structure (100) according to claim 14, wherein The difference in binding energy between the advantageous debonding interface (1) and the assembly interface (30) is at least 1000 mJ / m 2 .

16. Method of transferring a working layer (3) from a donor substrate (10) to a receiver substrate (20), said method comprising the following steps: a) providing a detachable structure (100) according to any one of claims 1 to 15, b) applying a mechanical stress to a detaching edge (100a’) of said detachable structure (100), said detaching edge (100a’) being positioned as close as possible to said assembly interruption zone (31), and said mechanical stress being able to initiate a separation wave (41) at said assembly interface (30) or at said favorable detaching interface (1), c) if the initiation of said separation wave (41) occurs at said assembly interface (30), said separation wave (41) is deflected into said favorable detaching interface (1) when said separation wave (41) crosses said assembly interruption zone (31), d) propagating said separation wave (41) at said favorable detaching interface (1) to cause a complete detachment of said detachable structure (100).

17. The method of claim 16, wherein, said mechanical stress is applied in such a way that the propagation direction of said separation wave (41) is perpendicular to at least one straight segment of the perimeter of said at least one cavity (31a) of said assembly interruption zone (31).

18. The method of claim 16 or 17, wherein, said mechanical stress is applied in such a way that the propagation direction of said separation wave (41) is perpendicular to the straight segment of the perimeter of said at least one cavity (31a) having the largest transverse dimension.

19. The method of claim 16 or 17, wherein, said mechanical stress is applied by inserting a bevel blade (40) between an edge of said receiver substrate (20) and an edge of said donor substrate (10).

20. The method of claim 16 or 17, wherein, Step a) comprises: - providing said donor substrate (10) comprising said working layer (3) disposed on said initial substrate (2), said favorable detaching interface (1) being located between said working layer (3) and said initial substrate (2), - providing a receiver substrate (20), - creating, in a peripheral region of said receiver substrate (20) or of said working layer (3), an opening to at least one cavity (31a) belonging to an assembly face (20c) of said receiver substrate (20) or to an assembly face (3c) of said working layer (3), - assembling said working layer (3) and said receiver substrate (20) at their respective assembly faces (3c, 20c).

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