METHOD FOR MANUFACTURED A DONOR SUBSTRATE

Abstract

The invention relates to a method for manufacturing a donor substrate comprising the steps of A: providing a handling substrate, B: providing a target substrate, C: attaching the target substrate to the handling substrate, and D: rectifying, in particular by grinding, the target substrate attached to the handling substrate, to form the donor substrate, the method being characterized in that a waiting period of predetermined duration is observed between step C and step D. Figure 1 for the abstract

Description

Title of the invention: METHOD FOR PRODUCING A DONOR SUBSTRATE Field of invention

[0001] The invention which is the subject of the present application relates to a method for manufacturing a donor substrate. The invention finds its application in particular in the field of manufacturing multilayer substrates, such as for example piezo-on-insulator (POI) or silicon-on-insulator (SOI) substrates. Technological background of the invention

[0002] It is known in the art to manufacture a donor substrate, also called a pseudo-donor substrate (PSD), which is suitable for transferring a layer of said donor substrate onto a support substrate. A PSD typically comprises at least one handling substrate, in particular of a semiconductor material such as silicon or sapphire, and a target substrate, one layer of which is intended to be transferred. A PSD is used in particular in the context of manufacturing a multilayer substrate using a SmartCut® type method.

[0003] The main advantage of implementing a PSD for layer transfer is that it overcomes the parasitic mechanical forces that can be induced by a thermal expansion differential between a support substrate and a layer deposited on the support substrate. Thus, by adapting the thermal expansion coefficient of the donor substrate to that of the support substrate, deformation during heat treatments can be minimized.

[0004] An additional advantage of implementing a PSD lies in the manufacturing ergonomics, each donor substrate being able to be reused a number of times to provide a new layer to a new support substrate at each production cycle using a SmartCut® type process. This is then referred to as a “refresh” of the PSD.

[0005] Thus, FR 18 52573 A1 discloses a first method for manufacturing a donor substrate having good mechanical strength by polymerization of a photopolymerizable adhesive layer. This method makes it possible to avoid resorting to high-temperature manufacturing steps which can be costly and cause curvatures of the substrates.

[0006] In order to increase the production yield of multilayer substrates such as POIs or SOIs, it is conceivable to reduce the quality defects that may appear during and at the end of the manufacturing processes. In particular, material defects may be observed in the produced multilayer substrates, such as cracks or cracking initiations, particularly at the edges of the substrates. These defects can originate in the PSDs and be transferred or appear on other substrates produced by the transfer of a layer from the donor substrate to a support substrate, for example during a SmartCut® step. Thus, the appearance of quality defects results in some cases in production scrap. Subject of the invention

[0007] In view of the above, the present invention aims to provide a donor substrate manufacturing method which increases the production quality of donor substrates, and results in the reduction of the incidence of defects, in particular the incidence of defects observed on final multilayer substrates. Brief description of the invention

[0008] In this regard, the invention relates to a method for manufacturing a donor substrate comprising the steps of A: providing a handling substrate, B: providing a target substrate, C: attaching the target substrate to the handling substrate, comprising bonding via an adhesive layer, the adhesive layer being a layer of a photopolymerizable material, in particular a layer of a photopolymerizable liquid with a thickness of 3 pm to 8 pm, and D: rectifying, in particular by grinding, the target substrate attached to the handling substrate, to form the donor substrate. The method is characterized in that a waiting time of a predetermined duration is observed between step C and step D.

[0009] According to an unexpected discovery of the inventors, the implementation of a waiting period of a predetermined duration between steps C and D can make it possible to achieve a significant reduction in the quantity of cracks observed in the multilayer substrates produced from donor substrates manufactured by the method which is the subject of the invention. Indeed, the waiting period can allow the constituent elements of the non-rectified donor substrate to rest and gain in robustness. In particular, the stabilizing effect of the adhesive layer of the photo-polymerizable material for the attachment of step C can be amplified. Thus, the non-rectified donor substrate can be made more resistant to the mechanical stresses undergone during the following rectification, as well as during a subsequent layer transfer step.Therefore, the rate of multilayer substrates, manufactured from donor substrates, at risk of cracking can be reduced and the overall quality of multilayer substrate production increased. For example, by reducing the amount of cracking at the substrate edge, the surface area or radius of a usable substrate can be increased.

[0010] According to one aspect of the invention, the target substrate is a piezoelectric substrate, in particular a piezoelectric substrate comprising a material chosen from quartz, lithium tantalate, lithium niobate, aluminum nitride, zinc oxide, gallium orthophosphate, barium titanate, langasite, langanite, gallium nitride, lead zirconate titanate or langatate.

[0011] Thus, the PSD obtained by the method can be used for the manufacture of POI substrates. Since piezoelectric substrates are particularly valuable due to their high price and diverse applicability, a reduction in production waste by the inventive method can be all the more advantageous.

[0012] According to one aspect of the invention, the handling substrate comprises a material selected from silicon, sapphire, aluminum nitride, silicon carbide or gallium arsenide.

[0013] By choosing one of these materials, the coefficient of thermal expansion of the handling substrate can be advantageously adapted to a subsequent use of the PSD for the manufacture of a multilayer substrate.

[0014] According to one aspect of the invention, the predetermined duration is at least 24 hours, preferably at least 48 hours, and preferably at least 105 hours.

[0015] By choosing the predetermined duration in such a manner, particularly large gains in the quality of substrates produced can be achieved. For example, cracking rates of 20% or less, 10% or less or 5% or less respectively can be achieved on multilayer substrates obtained from donor substrates manufactured by the method according to this aspect of the invention.

[0016] According to one aspect of the invention, the predetermined duration is less than 300 hours, preferably less than 200 hours, and preferably less than 150 hours.

[0017] By thus limiting the duration of the waiting time, a good balance between gain in production quality and reduction in production throughput can be maintained. According to one aspect of the invention, the predetermined duration is determined according to the material of the adhesive layer.

[0018] Thus the waiting time can be adapted to the adhesion and relaxation properties specific to each adhesive layer material. In particular, this can make it possible to precisely adapt the waiting time necessary to obtain a gain in quality of substrates produced.

[0019] According to one aspect of the invention, the predetermined duration is chosen, on the basis of a statistical study developing a cracking rate observed on multilayer substrates obtained from the donor substrates manufactured by this method according to the duration of the waiting time respected, so that said duration corresponds to the duration necessary to obtain a cracking rate of 20% or less, in particular 10% or less, or even more particularly 5% or less. In particular, the statistical study may result from tests comprising at least 500 manufactured donor substrates, for example in the form of wafers or "platelets" according to the terminology Anglo-Saxon.

[0020] By basing the duration of the waiting time on such a statistical study, the method can be adapted even more precisely to a desired objective of quality of donor substrate produced.

[0021] According to one aspect of the invention, the waiting time is respected under ambient conditions. Thus, the costs and bulkiness of environmental control equipment are avoided and the effect of the invention can be achieved.

[0022] Another object of the invention relates to a method for transferring a layer of a donor substrate onto a support substrate, comprising the steps of A: providing a donor substrate obtained by implementing one aspect of the method described above, B: forming a weakening zone in the target substrate so as to delimit the layer of the target substrate to be transferred, C: providing a support substrate, in particular comprising a material corresponding to a material of the handling substrate, D: attaching the donor substrate to the support substrate, and E: fracturing and separating the donor substrate along the weakening zone.

[0023] The implementation of this method can make it possible to obtain a multilayer substrate with a reduced incidence of material defects, as previously developed: by setting up a waiting time of a predetermined duration, the quality of the donor substrates obtained can be increased. As a result, the layer of the target substrate transferred onto the support substrate is also of higher quality.

[0024] The combination of the method of manufacturing a donor substrate with this method of transferring a layer of a donor substrate is particularly advantageous because the fractured donor substrate, i.e. the remainder of the donor substrate remaining after step E, can be reused. Thus, for example in the context of a "refresh" of a SmartCut® type process, the same residual donor substrate can, in a subsequent production cycle, be prepared to transfer another layer of the target substrate to another support substrate. Brief description of the drawings

[0025] The objects, features and advantages of the invention as set forth above will be more fully understood and appreciated by studying the following more detailed description of the invention, as well as the accompanying drawings.

[0026] [Fig.l] schematically represents the successive steps of a method of manufacturing a donor substrate according to one embodiment of the invention.

[0027] [Fig.2] schematically represents the successive steps of a method of transferring a layer according to an embodiment of the invention.

[0028] For reasons of readability of the figures, the elements illustrated are not necessarily represented to scale, nor relative to each other, nor in their di- relative Cartesian dimensions.

[0029] [Fig.3] shows a graph extracted from test results carried out as part of the optimization of the manufacturing process. Detailed description of the drawings

[0030] An embodiment of a method for manufacturing a donor substrate 1 according to the invention is described with reference to [Fig.l]. [Fig.l] schematically illustrates the successive steps of manufacturing the donor substrate 1.

[0031] The method comprises a step E1 of providing a handling substrate 3, also called a “handle substrate”. The handling substrate 3 may comprise a material chosen from silicon (Si), sapphire (Al 2O3), aluminum nitride (AIN), silicon carbide (SiC), gallium arsenide (GaAs), quartz (SiO2), or another glass.

[0032] The method comprises a step E2 of providing a target substrate 5. The target substrate 5 is a substrate which is intended to be subsequently transferred at least in part onto a support substrate.

[0033] According to one embodiment of the method, the target substrate 5 may be a piezoelectric substrate. For example, the target substrate 5 may comprise a material selected from LTO (La2Ti2O7), quartz (SiO2), lithium tantalate (LiTaO3), lithium niobate (LiNbO3), aluminum nitride (AIN), zinc oxide (ZnO), gallium orthophosphate (GaPO4), barium titanate (BaTiO3), langasite (La3 Ga5SiOi4), langanite (La3Ga5.5Nbo.50i4), gallium nitride (GaN), lead zirconate titanoate (PZT) or langatate (La3Ga5.5Tao.50i4). These materials are particularly suitable for bulk elastic wave (BAW) or surface elastic wave (SAW) applications, such as a SAW sensor or a POI-based BAW filter.

[0034] According to another embodiment, the target substrate 5 may be a substrate comprising a semiconductor material such as silicon (Si), sapphire (Al2O3), aluminum nitride (AIN), silicon carbide (SiC), gallium arsenide (GaAs), quartz (SiO2), or another glass.

[0035] In a step E3, the target substrate 5 is attached to the handling substrate 3. In this embodiment, the attachment of step E3 is carried out by bonding, in particular by bonding via an adhesive layer 7. Preferably, an adhesive layer of a photopolymerizable material is used. Such a material can be polymerized when it is irradiated by a light flux. As an example, an adhesive layer 7 with a thickness of 3 μm to 8 μm of the product sold under the reference “NOA 61” by the company NORLAND PRODUCTS can be formed in this step, then subjected to UV radiation through the exposed surface of the target substrate 5 attached to the handling substrate 3.

[0036] According to the invention and unlike the methods known in the art of manufacturing a donor substrate, the process continues with a step E4 during which the manufacturing process is interrupted for a waiting period of a predetermined duration. The waiting period is at least 24 hours, and preferably 105 hours.

[0037] The waiting time is respected under ambient conditions. That is to say, during the waiting, the target substrate 5 attached to the handling substrate 3 is preserved at an ambient temperature, in particular between 20°C and 26°C of temperature, and at an ambient pressure, in particular between 950 hPa and 1030 hPa of pressure.

[0038] Finally, the target substrate 5 attached to the handling substrate 3 is subjected to a grinding step E5. Grinding is understood to mean a surface treatment aimed at reducing the roughness of the exposed surface 9 of the target substrate 5 attached to the handling substrate 3. Grinding is preferably carried out by grinding or by chemical-mechanical planarization, or CMP according to the English term "Chemical-mechanical polishing".

[0039] This manufacturing method makes it possible to obtain a donor substrate which solves the problem of the invention. The use of a handling substrate 3 is advantageous, for example, for manufacturing an SOI or POI substrate, because, unlike conventional methods such as epitaxial growth, it makes it possible to avoid deformations induced by high temperatures during heat treatments.

[0040] The bonding by adhesive layer 7 in step E3 ensures satisfactory mechanical cohesion of the two bonded substrates. By using a photo-polymerizable material, the attachment can be carried out without resorting to bonding under high temperature, for example at more than 200°C.

[0041] The rectification in step E5 makes it possible to obtain a surface which is sufficiently smooth and of uniform flatness for subsequent transfer of a layer onto a support substrate, for example using a SmartCut® type process.

[0042] Unexpectedly, the inventors discovered that fewer defects are observed when the donor substrates 1 have undergone the waiting period between the attachment step E3 and the rectification step E5. The effect is particularly advantageous in comparison with multilayer substrates, for example POI or SOI, obtained with donor substrates 1 manufactured without observing the waiting period. Indeed, the waiting period allows the constituent elements of the non-rectified donor substrate 1, i.e. the target substrate 5 attached to the handling substrate 3, to gain in robustness, before undergoing the rectification, and in particular before undergoing a subsequent layer transfer step during the manufacture of a multilayer substrate, for example of the SOI or POI type by SmartCut®. Thus, the non-rectified donor substrate is made more resistant to the mechanical stresses undergone during the rectification step or during a subsequent layer transfer.Therefore, the number of donor substrates 1 manufactured likely to lead to defects, and in particular to give rise to . to cracks, following the transfer of a layer from the target substrate, is reduced and the overall quality of production increased.

[0043] A method of transferring a layer from a donor substrate to a support substrate according to one embodiment of the invention is described with reference to [Fig. 2]. The method described relates to a donor substrate 1 obtained according to the method described in [Fig. 1].

[0044] The method of transferring a layer begins with a step E1 1 of providing the donor substrate 1 resulting from step E4 of the manufacturing method according to the embodiment of the invention of [Fig.l].

[0045] Next, a weakening zone 11 is formed in the target substrate 5 of the donor substrate 1 in a step E12. The zone 11 is formed so as to delimit a layer 13 of the target substrate 5 to be transferred. The layer 13 is delimited in the target substrate 5 by the weakening zone 11 on the one hand, and by the ground surface 9 on the other hand. The weakening zone 11 is preferably formed by implantation of ions, for example of hydrogen ions or of a rare gas, such as helium. The ion dose, the distribution of the ion dose, and the implantation energy of the ions can vary and determine the properties of the weakening zone 11 formed. The depth of the weakening zone 11 in the target substrate 5 determines the thickness of the layer 13 to be transferred.

[0046] A support substrate 15 is provided in a step E13. The support substrate 15 may preferably comprise a material selected from silicon (Si), sapphire (Al2O3), aluminum nitride (AIN), silicon carbide (SiC), gallium arsenide (GaAs), quartz (SiO2), or another glass. The support substrate has a main surface 17.

[0047] Preferably, the material of the handling substrate 3 of the donor substrate 1 has been chosen so as to have a thermal expansion coefficient value equivalent or similar to the thermal expansion coefficient value of the support substrate 15, onto which the layer 13 is intended to be transferred. A similar coefficient value typically corresponds to a value between +10% and -10% of the reference value.

[0048] Thus, to obtain a suitable thermal expansion coefficient value, the support substrate 15 and the handling substrate 3 are preferably made of the same material.

[0049] In step E14, the donor substrate 1 is attached to the support substrate 15. The donor substrate 1 is attached by attaching the ground surface 9 along the main surface 17 of the support substrate 15, forming a complex 19.

[0050] The attachment can be carried out for example by bonding via a dielectric layer deposited on at least one of the two surfaces 9, 17 to be bonded. The The dielectric layer may be, for example, a glass layer deposited by centrifugation on the target substrate 5 using the spin-on glass (SOG) method. The attachment may be reinforced by subjecting the surface to be bonded, on which the dielectric layer has not been deposited, to a suitable treatment to subsequently allow hydrophilic molecular bonding with the surface on which the dielectric layer has been deposited. The attachment may also be reinforced by thermal densification annealing, for example at a temperature of approximately 250°C. In this case, the parasitic mechanical forces induced by a thermal expansion differential between the support substrate 15 and the target substrate 5 are at least partially offset by the attachment of the target substrate 5 to the handling substrate 3, on the side opposite the support substrate 15. Thus, the thermal expansion coefficients of the substrates 3 and 15 on either side of the target substrate 5 are similar.

[0051] Then, in step E15, the complex 19 of the donor substrate 1 comprising the weakened target substrate 5, attached to the support substrate 15, is fractured along the weakening zone 11 and separated into two parts: on the one hand the final multilayer substrate 21, such as a POI or SOI substrate, comprising the support substrate 15 onto which the delimited layer 13 of the target substrate 5 has been transferred, and on the other hand the remainder of the donor substrate after the fracturing step, designated fractured donor substrate 23.

[0052] The fractured donor substrate 23 can be reconditioned, or refreshed, in order to be resubmitted to step E12 of forming a weakening zone 11. Thus, steps E12, E13, E14, and E15 can be repeated a number of times based on a single original donor substrate 1 provided, in order to produce several final multilayer substrates 21, such as POIs or SOLs. The number of possible refreshes per donor substrate 1 is limited by the thickness of the target substrate 5 of the donor substrate 1, from which a layer 13 is removed at each refresh iteration. On the other hand, material defects present in the target substrate 5 of the donor substrate 1 provided in step E11 remain there, or even become more significant throughout the process described with reference to [Fig.2]. These defects are transmitted to step E14 at each cycle on the support substrate 15 by the transferred layer 13.An increase in the general quality of the donor substrate 1 supplied in step E1 1 therefore cascades positively on all the products resulting from the process.

[0053] [Fig. 3] graphically reproduces the results of observation of cracks on a sample of multilayer substrates 21, for example POI or SOI, manufactured by the embodiment of the method of the invention described above. The sample of [Fig. 3] comprises 818 donor substrates 1 which were manufactured by the method of [Fig. 1] respecting varied waiting times, up to a duration of 300 h. The substrates of the sample comprise a handling substrate 3 made of silicon (Si), a target substrate 5 made of LTO (La2Ti2O7) and an adhesive layer 7 made of NOA 61.

[0054] [Fig. 3] shows a graph relating to a sample of final multilayer substrates 21 following step E15 of the process of [Fig. 2] in a first production cycle. The donor substrate 1, from which the sample of substrates 21 was produced, has therefore not yet been subjected to a "refresh" in the context of a SmartCut® process. Each point on the graph corresponds to a multilayer substrate 21 of the sample for which the quality status, i.e. the presence or absence of material defects, was observed and recorded as a function of the waiting time observed in step E5 of the manufacturing process of the donor substrate 1 of step E11.

[0055] Thus, the sample of verified multilayer substrates is classified and quantified into three groups: without material defect (S), presenting an incipient crack (A), and presenting a crack (F). An incipient crack is a crack that does not cross the thickness of the substrate.

[0056] Thus, depending on the waiting time observed during the manufacture of the donor substrate 1, the rate of absence of material defects T_a = S / (S+A+F) and the rate of absence of cracking T_b = (S+A) / (S+A+F) can be determined. In [Fig. 3], T_a is represented by the reference 31 and T_b by the reference 33. The curves 31 and 33 representing the rates T_a and T_b are obtained by a non-linear regression of the statistical results of the observations.

[0057] By studying curves 31 and 33 of [Fig. 3], it is apparent that the longer the waiting time of step E4 respected, the higher the rates T_a and T_b of multilayer substrates manufactured without defects, respectively without cracking. Thus, the longer the waiting time, the higher the production quality obtained increases.

[0058] [Fig. 3] makes it possible to identify that, in general, the material defect incidence rate T_i (= 1 - T_a) can be reduced by choosing a predetermined duration of at least 24 h, preferably at least 48 h, and preferably at least 105 h. These values ​​make it possible to obtain particularly large gains in the quality of substrates produced. Thus, the graph in [Fig. 3] shows material defect absence rates T_a of the order of 68%, 75% or 81% for these periods of 24 h, 48 h and 105 h respectively. Furthermore, cracking rates T_f (= 1 - T_b) of approximately 20%, 10%, and 5% for these periods of 24h, 48h and 105h respectively, as identified by reference 35, can be read in the graph of [Fig.3].

[0059] For example, this study allows reading by reference 37 that by respecting a waiting time of 105 h during step E4, a quality gain of 21%, compared to the level of hardware defect without respecting the waiting time, is acquired.

[0060] At the same time, it is also apparent from curves 31 and 33 of [Fig. 3] that the increase in the gain in quality of manufactured donor substrates decreases the longer the waiting time respected. However, it is preferable not to interrupt the production lines and delay the production of a donor substrate for too long. Thus, it It is preferable to limit the waiting time to no more than 300 hours, preferably no more than 200 hours, and preferably no more than 150 hours. By limiting the waiting time in this way, a good balance between quality gain and slowing down the production flow can be maintained.

[0061] According to a variant of the invention, the predetermined duration of step E4 can be chosen, based on curves 31 or 33 developed by the statistical study represented by [Fig. 3]. For example, a quality objective can be set, and the duration of the waiting period to be respected can be read on the curve 31 or 33 concerned. For example, by setting a quality objective of a cracking rate of at most 3%, it is sufficient to identify the waiting period corresponding to the value T_b = 97%, which in this case corresponds to a period of 105 h. By thus basing the duration of the waiting period on the results of the study, the method is precisely adapted to the desired quality objective.

[0062] Alternatively, the predetermined waiting time of E4 can be determined by analyzing the gradient of curves 31 or 33. For example, the tangent of curve 31 at x=0h, or the linear extrapolation of the material defect-free rate T_a between x=0h and x=1h, can be determined, as indicated by reference 39. Tangent 39 can be crossed with asymptote 41 of the corresponding rate T_a to obtain a waiting time of 70 h for a value T_b of 90% or T_a of 78% of multilayer substrate 21.

[0063] According to an embodiment described above with reference to [Fig.l], the attachment of the target substrate to the handling substrate comprises a bonding step by adhesive layer. In this case, it is appropriate to adapt the duration of the waiting time to the material of the adhesive layer, in particular to the adhesion and relaxation properties specific to the material of the chosen adhesive layer. For example, a comparative coefficient can be developed comparing the material of the chosen adhesive layer with the attachment mode chosen in a reference case. The comparative coefficient can then be used to adapt the duration of the waiting time chosen for the manufacture of the donor substrate more precisely. This makes it possible to precisely adapt the waiting time necessary to obtain a maximum gain in quality of multilayer substrates 21, in particular POI or SOI, produced.

[0064] Thus, by providing a donor substrate according to the invention, for example a donor substrate 1 obtained according to the method described with reference to [Fig.l], the method of transferring a layer can also be improved and provide more qualitative multilayer substrates. For example, by using the SmartCut ® method, commercial SOI and POI substrates can be obtained with a higher yield by virtue of the reduction in material defects observed.

Claims

Claims

1. A method for manufacturing a donor substrate, comprising the following steps: A: providing a handling substrate (3), B: providing a target substrate (5), C: attaching the target substrate (5) to the handling substrate (3), comprising bonding by means of an adhesive layer (7), the adhesive layer (7) being a layer of a photopolymerizable material, in particular a layer of a photopolymerizable liquid with a thickness of 3 μm to 8 μm, and being polymerized upon irradiation with a light flux, D: rectifying, in particular by grinding, the target substrate (5) attached to the handling substrate (3), to form the donor substrate (1), said method being characterized in that a waiting time of a predetermined duration is observed between step C and step D.

2. The method of claim 1, wherein the target substrate (5) is a piezoelectric substrate, in particular a piezoelectric substrate comprising a material selected from quartz, lithium tantalate, lithium niobate, aluminum nitride, zinc oxide, gallium orthophosphate, barium titanate, langasite, langanite, gallium nitride, lead zirconate titanoate or langatate.

3. A method according to claim 1 or claim 2, wherein the handling substrate (3) comprises a material selected from silicon, sapphire, aluminum nitride, silicon carbide, or gallium arsenide.

4. Method according to one of claims 1 to 3, in which the predetermined duration is at least 24 h, preferably at least 48 h, and preferably at least 105 h.

5. Method according to one of claims 1 to 4, in which the predetermined duration is less than 300 h, preferably less than 200 h, and preferably less than 150 h.

6. Method according to one of claims 1 to 5, wherein the predetermined duration is determined depending on the material of the adhesive layer (7).

7. Method according to one of claims 1 to 6, in which the predetermined duration- completed is chosen, on the basis of a statistical study, in particular a study resulting from tests comprising at least 500 donor substrates (1), developing a cracking rate observed on multilayer substrates (21) obtained from the donor substrates (1) according to the duration of the waiting period observed, so that said duration corresponds to the duration necessary to obtain a cracking rate of 20% or less, in particular 10% or less, or even more particularly 5% or less.

8. Method according to one of claims 1 to 7, in which the waiting time is respected under ambient conditions.

9. A method of transferring a layer from a donor substrate (1) to a support substrate (15), comprising the following steps: A: the provision of a donor substrate (1) obtained by implementing the method according to one of claims 1 to 8; B: forming a weakening zone (11) in the target substrate (5) so as to delimit the layer (13) of the target substrate (5) to be transferred; C: providing a support substrate (15), in particular comprising a material corresponding to a material of the handling substrate (3) D: attaching the donor substrate (1) to the support substrate (15) E: fracturing and separating the donor substrate (1) along the weakening zone (11).

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