FR2926398A1 - LAYER TRANSFER WITH DECREASE IN POST-FRACTURE ROUGHNESS - Google Patents

Abstract

The invention relates to a method of transferring a layer of a donor substrate to a recipient substrate comprising: a first step (S10) of ion implantation of hydrogen in the donor substrate intended to form a layer of microcavities or platelets a second step (S12) of ion implantation, a step (S13) for bonding the face of the donor substrate with a face of the receiving substrate, a detachment step (S14) for causing cleavage at the level of the layer of microcavities or platelets formed in the donor substrate.The method further comprises, between the two steps of implantation, a step (S11) of thermal annealing of priming carried out at a temperature between 300 degrees C and 700 degrees C and for a duration less than 10% of the time necessary to cause cleavage at the layer of microcavities or platelets formed in the donor substrate at the temperature used during said step e heat treatment priming annealing.

Description

Technical field and prior art

The present invention relates to a method of transferring a layer of a donor substrate to a receiver substrate used in the manufacture of heterostructures such as SeOI ("Semiconductor On Insulator") type structures for electronic, microelectronic applications. and optoelectronic. A well-known technology for producing heterostructures by transfer of layers is Smart CutTM technology. An example of implementation of Smart Cut ™ technology is described in particular in US 5,374,564 or in the article by A.J. Auberton-Hervé et al. 15 entitled "Why can Smart-Cut Change the Future of Microelectronics?", Lat. Journal of High Speed Electronics and Systems, Vol.10, Nol, 2000, p.131-146. This technology involves the following steps: a) Bombarding a face of a donor substrate (for example in silicon) with light ions of the hydrogen or rare gas type (for example hydrogen and / or helium) in order to implant these ions in sufficient concentration in the substrate, the implanted zone for creating an embrittlement layer by formation of microcavities or platelets, intimate contact (bonding) of this face of the donor substrate 25 with a receiving substrate, and c) annealing detachment ("splitting annealing") for causing, by crystal rearrangement and pressure in microcavities or platelets formed from the implanted species, fracture or cleavage at the implanted layer to obtain a heterostructure resulting from the transfer of the donor substrate layer on the receiving substrate. However, after such a transfer, both the transferred layer and the donor substrate have a surface roughness US 2006/0060943 and US 2007/0037363 disclose methods of co-implantation, i.e. at least two different gaseous species, which make it possible to limit the surface roughness of the transferred layer and of the donor substrate after transfer.

US 6,150,239 also discloses a method of coimplanting a donor substrate to transfer a layer of this substrate to a receiving substrate that allows detachment at a lower temperature and decrease post-fracture roughness. The method described in this document mainly comprises the following steps: implantation of a donor substrate with a first gaseous species capable of trapping hydrogen in the substrate, implantation of hydrogen in the donor substrate delimiting the layer to be transferred, application of heat treatment at a temperature below the detachment temperature to form microcracks in the substrate, bonding the donor substrate to a receiving substrate, applying detachment annealing at a temperature to cause cleavage / fracture of the donor substrate at level of the implanted area so as to transfer the layer of the donor substrate on the receiving substrate. However, even with these existing solutions, the reduction in surface roughness after detachment is still limited.

Summary of the invention

The object of the present invention is to propose a solution which makes it possible to further reduce the surface roughness after transfer (post-fracture) present both on the transferred layer and on the donor substrate. To this end, the invention relates to a method of transferring a layer of a donor substrate to a recipient substrate comprising: a) a first step of ion implantation of hydrogen in the donor substrate intended to form a layer of microcavities or platelets, b) a second ion implantation step, c) a step of bonding the face of the donor substrate with the receiving substrate, for example by molecular adhesion, d) a detachment step to cause cleavage at the level of the layer of microcavities or platelets formed in the donor substrate, characterized in that it further comprises, after step a) and before step d), a priming annealing heat treatment step carried out at a temperature of between 300 ° C and 700 ° C and for less than 10% of the time necessary to cause cleavage at the level of the layer of microcavities or platelets formed in the donor substrate at the user temperature in said step of initiating annealing heat treatment. The initiation annealing heat treatment step is preferably carried out between the two implantation steps a) and b). The initiation annealing heat treatment of the process of the invention is carried out with a thermal budget (temperature / time pair corresponding to the energy provided during the heat treatment) voluntarily lower than that required to cause cleavage or fracture at the of the layer of microcavities or platelets formed during step a). For this purpose, the temperature of the thermal budget is chosen in a range between 300 ° C and 700 ° C which corresponds to the temperatures typically used during annealing to cause the cleavage / fracture of the implanted substrates, so-called detachment annealing. In a well-known manner, a detachment annealing time is given which is determined as a function of the temperature used for this annealing. Typically, the higher the detachment annealing temperature, the shorter the duration of the cleavage / fracture at the implanted zone. In general, the detachment annealing is carried out at a temperature of between 300 ° C. and 700 ° C. and for a duration ranging from a few seconds (for the highest temperatures) to several tens of hours (for lowest temperatures). According to the method of the invention, the thermal budget of the priming annealing must be defined so as to apply less than 10% of the thermal budget typically required to cause the cleavage / fracture of the implanted donor substrate, the duration of the thermal budget is limited less than 10% of that required to achieve said cleavage / fracture at the temperature used during the initiation annealing heat treatment.

Thus, by previously subjecting the implanted donor substrate to a heat treatment voluntarily limited to a duration of less than 10% of the usual duration of a detachment annealing, the development / growth process of the defects resulting from the implantation in the process is interrupted. donor substrate to limit the interaction between partially formed microcracks in a localized area around the maximum concentration of implanted hydrogen and microcavities or platelets present above and below this zone. Thus, the detachment itself is then performed with a donor substrate already comprising localized microcracks. During detachment, these microcracks will develop preferentially with respect to platelets located above and below, and thus to obtain a localized fracture line at the microcracks generated during the previous heat treatment step. The surface roughness of the transferred layer and the donor substrate after detachment is then reduced. The detachment can be obtained by heat treatment alone. In this case, an annealing is applied at a temperature and for a duration to cause cleavage of the donor substrate at the level of the layer of microcavities or platelets. Detachment by cleavage of the donor substrate can also be obtained by applying a mechanical separation force at the layer of microcavities or platelets (introducing for example a blade at this location). The application of the mechanical separation force can furthermore be combined with a heat treatment.

This limitation of duration during the heat treatment of priming annealing has been defined by the inventors following a study of the physical process of development / growth of defects leading to the rupture of the donor substrate during a detachment annealing. This study is detailed below. According to one aspect of the invention, step b) corresponds to an ion implantation of hydrogen in the donor substrate, this second implantation step being performed with the same implantation energy as that used in step a) .

According to another aspect of the invention, step b) corresponds to an ion implantation of helium in the donor substrate, this second implantation step being carried out with an implantation energy determined according to that used in FIG. step a) so that the zone comprising the maximum concentration of implanted helium coincides with the zone comprising the maximum concentration of hydrogen implanted during step a). According to yet another aspect of the invention, step b) corresponds to an ion implantation in the donor substrate of at least one species capable of reacting with the hydrogen implanted during step a), this second step of implantation being performed with an implantation energy different from that used in step a). Implantation is performed with an implantation energy which is preferably lower than that used in step a) so that the maximum peak of reactive species implantation is above the peak of maximum concentration of hydrogen. implanted. The species capable of reacting with the hydrogen implanted during step a) is chosen at least from fluorine, silicon, nitrogen and carbon.

BRIEF DESCRIPTION OF THE FIGURES The characteristics and advantages of the present invention will become more apparent from the following description, given by way of non-limiting indication, with reference to the accompanying drawings, in which: FIG. 1 shows an example of hydrogen ion implantation in a silicon substrate, FIG. 2 very schematically represents the state of a silicon substrate implanted with hydrogen ions after an annealing time of less than 100/0 of the total duration of the detachment annealing, FIGS. 3A to 3E are diagrammatic sectional views showing the transfer of a Si layer according to an embodiment of the invention, FIG. 4 is a flowchart of the steps implemented in FIGS. 3A to 3E, FIGS. 5A. 5E are diagrammatic sectional views showing the transfer of a Si layer according to another embodiment of the invention, FIG. 6 is a flowchart of the steps involved. 5A to 5E, FIGS. 7A to 7E are schematic cross-sectional views showing the transfer of a Si layer according to another embodiment of the invention, FIG. flowchart of the steps implemented in FIGS. 7A to 7E.

Detailed description of embodiments of the invention

The present invention applies to any layer transfer method using at least one hydrogen ion implantation of a donor substrate to delimit a layer to be transferred by a weakening plane, the bonding of the donor substrate implanted on a receiving substrate and the application of a high temperature heat treatment (detach annealing) and / or a mechanical separation force to detach the layer to be transferred from the donor substrate as in Smart CutTM technology. The principle of the invention consists in favoring the development of microcracks in a restricted zone, corresponding to the zone of maximum implanted hydrogen concentration, to the detriment of platelets / microcavities located above and below this zone. Thus, by reducing the interactions between these microcracks and platelets, a final cracking line is obtained in the localized substrate at the restricted zone of the microcracks, which has the effect of reducing the surface roughness after detachment. The control of the localized development of microcracks according to the invention is obtained in particular with a heat treatment, called priming annealing, which is carried out at a temperature usually used during a detachment annealing (between 300 ° C. and 700 ° C. ) but for a time limited to less than 10% of that required to cause the detachment of the substrate at this temperature. This limitation of duration of the priming annealing was determined by the inventors after analysis of the physical process occurring during a detachment annealing of an implanted substrate resulting in the rupture of the latter. As a reminder, FIG. 1 illustrates an example of hydrogen implantation of a silicon substrate 101 comprising an oxide layer 102 (for example SiO 2). During implantation, the silicon substrate 101 is subjected to bombardment of H + ions 100. The H + ions penetrate into the substrate and are braked to a determined depth in the substrate 101, which makes it possible to create a layer of defects The layer 103 forms an embrittlement layer which will make it possible to cause the fracture of the substrate during a subsequent heat treatment.

The layer 103 extends over a certain thickness in the substrate, typically to a thickness of about 150 nm, and has a high concentration of hydrogen in its center (hydrogen peak) and a lower concentration in its upper part and its lower part. In accordance with the Smart CutTM technology, the silicon substrate 101 thus implanted is then subjected to a heat treatment called splitting annealing ("splitting annealing") which causes the growth and development of defects created by the implanted species causing final fracture (cleavage) of the substrate at layer 103. The detachment annealing in Smart Cu 8 technology for substrates of silicon type, and more generally a Group IV material, is carried out in a temperature range typically between 300 ° C and 700 ° C for a fixed period (the temperature / duration pair corresponds to the thermal budget of the detachment annealing). In a well known manner, the temperature and duration of the detachment annealing are defined according to the implantation conditions and in particular according to the implantation dose. Experimental tests carried out on silicon substrates implanted with hydrogen ions have shown that the growth of the defects responsible for the rupture of the substrate during detachment annealing is broken down into three phases: 1) A first phase corresponding to a transient process very short which occurs from the first moments of the annealing of detachment, that is to say before having reached 10 ° lo of the duration of the annealing of detachment to be carried out, and at the end of which the formation of microcracks is already effective ; 2) a second phase corresponding to a "slow" growth phase of the microcracks formed during the first phase; and 3) a third phase corresponding to a catastrophic process of geometric coalescence of the microcracks leading to fracture of the substrate along a fracture line and allowing detachment of the silicon thin film. The layer transfer method of the present invention was defined as a result of the identification and analysis by the inventors of the physical phenomena that occur in the first moments of detachment annealing. The inventors have thus demonstrated that from the first moments of the detachment annealing (less than 10% of the time necessary to cause the cleavage / fracture at the temperature used) a transient process occurs. During this transient process and because of implantation, dissociation of temperature-unstable hydrogen species occurs which leads to the formation of high molecular hydrogen H2 in the substrate material. Platelet-type defects, present at implantation, will then absorb a large fraction of this molecular hydrogen. The gaseous phase thus formed within a defect will induce its sudden pressurization leading to localized cracking of the substrate. At the end of this transient process, there are two types of defects coexisting in the substrate, namely: large microcracks of several microns already nucleated in the first moments of the annealing of detachment by pressurizing the platelets close to the peak of hydrogen of the implanted zone (zone comprising a high density of initial defects and a high concentration of hydrogen available to form gaseous H 2), and plate-like defects of a few tens of nanometers which are less influenced by the transient process, that is to say, that have not yet led to the formation of microcracks, and which are mostly below and above the peak of hydrogen. The nucleation of the microcracks by pressurizing the platelets is directly controlled by the kinetics of arrival of the hydrogen gas. Since a large part of the microcracks is already formed at the end of the transient process, the cracking path is already almost determined after a very short annealing time. This time depends on the dose and the implantation temperature. In the case of hydrogen implantation of a monocrystalline silicon substrate with an implantation dose of typically between 4.1016 and 1.10 atoms / cm 2, the annealing time required for the formation of the main microcracks is less than 10%. the total duration of the detachment annealing necessary to result in the fracture of the substrate, whatever the annealing temperature envisaged in the temperature range usually used in this case, namely any temperature between 300 ° C. and 700 ° C.

FIG. 2 very schematically illustrates the state of the silicon of a substrate implanted with H + ions at the end of the transient process, that is to say after a duration corresponding to approximately 10% of the total duration of the detachment annealing. . The portion of the substrate shown in Figure 2 corresponds to the defect layer resulting from the implantation. As explained above, the silicon has at this stage of detachment annealing both micro-cracks 110 that result from the growth of certain platelets essentially located in the vicinity of the center of the implantation zone (hydrogen peak) and which are strongly pressurized by undergoing important direct mutual interactions (geometric coalescence). Silicon also has platelets 111 located further from the center of the implantation zone and whose growth is only slightly influenced by the transient process (low pressurization). At this stage, it is already possible to mechanically propagate the fracture from the microcracks (for example by inserting a blade). It is observed that the microcracks 110 are located in a zone of limited thickness relative to the thickness of the implantation zone on which extends all the platelets resulting from implantation. If a final cracking path is extrapolated from the microcracks 110 (final dotted cracking path in FIG. 2), a fracture line is obtained which extends over a certain thickness which corresponds to the post-fracture roughness. which would be obtained if the annealing of detachment was continued over its total duration.

Consequently, the post-fracture roughness is intimately related to the nucleation phase of the microcracks. A reduction in the post-fracture roughness can then be obtained by controlling the dissociation phase of the unstable hydrogenated species providing the molecular hydrogen to the platelets during the detachment annealing, so as to promote the development of microcracks at the peak at the expense of the growth of platelets above and below the restricted zone of microcracks. In this way, the microcracks / platelets interactions which contribute to the increase of the post-fracture roughness are reduced.

According to the present invention, the transfer method comprises at least one initiation annealing step whose duration is less than the% of the critical fracture time, that is to say the duration of the detachment annealing necessary to cause the fracture of the implanted substrate as a function of the temperature used. The process according to the invention also comprises, following the initiation annealing, a second step of ion implantation of at least one species (hydrogen, helium, or any other active species) which makes it possible to disrupt the growth of the microcracks and / or platelets during a detachment annealing carried out continuously. Several examples of implementation of the layer transfer method of the invention will now be described. All of the examples described below have been carried out within the framework of the well-known fabrication of an SOI structure which usually comprises at least the following steps: implantation of a silicon donor substrate, bonding of the implanted donor substrate onto a substrate silicon receiver, for example by molecular adhesion, detachment seal allowing the fracture of the donor substrate and the transfer of a layer or a film of silicon on the receiving substrate. The examples described below have all been made with a monocrystalline silicon donor substrate having a thickness of between about 700 to 800 μm and a monocrystalline silicon receiving substrate having a thickness of between about 700 to 800 μm. Example 1

This example which is described with reference to FIGS. 3A to 3E and 4 comprises the following steps: Step S10: first hydrogen implantation in which a donor substrate 11 is subjected to ionic bombardment of H + hydrogen ions through the plane face 17 of the substrate comprising an oxide layer (SiO 2) 12. The implantation of the H + ions is carried out with an implantation energy of between 10 keV and 210 keV, for example 40 keV, and a dose of implantation between 4.1016 and 1.1017 atoms / cm 2. These implantation conditions make it possible to create a plate-like defect layer 13 parallel to the face 17 of the substrate delimiting, on the one hand, a thin film 14 in the upper region of the substrate 11 and, on the other hand a portion 15 in the lower region of the substrate corresponding to the remainder of the substrate 11 (Fig. 3A); Step S11: initiation annealing at a temperature of between 300 ° C. and 700 ° C. corresponding to the temperature normally used for detach annealing. The duration of the initiation annealing is, in accordance with the present invention, less than 10 ° C. % of the total time required to cause cleavage of the implanted substrate at the considered temperature. This limitation of the duration of the annealing of initiation makes it possible to interrupt the growth of the structural defects (microcracks and platelets) before the end of the transient process and to avoid the blistering of the silicon (FIG. 3B); Stage S12: second hydrogen implantation carried out by ionic bombardment 19 of H + hydrogen ions with the same energy as in the first implantation step to implant the hydrogen at the same depth (FIG. 3C). The first implantation is performed with an implantation dose "usually" used to allow the release of the layer to be transferred in order to obtain and control the transient process and the nucleation of microcracks. The implantation dose used during the second implantation takes into account the dose used in the first implantation. By way of example, if the first implantation is carried out with an implantation dose of 5 × 10 16 atoms / cm 2, the second implantation is carried out with an implantation dose of between 1 × 10 16 and 3 × 10 16 atoms / cm 2 in order to obtain a dose of Cumulative hydrogen implantation between 6.1016 and 8.1016 atoms / cm 2. The second implantation is generally performed with an implantation dose of between 1.1016 and 3.1016 atoms / cm 2. Step S13: bonding the donor substrate 11 with a receiving substrate 16 (FIG. 3D); Step S14: detachment annealing for causing fracture of the donor substrate 11 and the actual transfer of the thin film 14 onto the receiving substrate 16 (FIG. 3E). The thin film 14 has, after step 14, a post-fracture surface roughness of between 60 and 70 angstroms (A) RMS and between 13,800 and 900 Å in peak-to-valley amplitude (peak-to-valley). hollow) for scanning areas point by point ("scan area", made for example by atomic force microscope) of 10 * 10 microns. By way of comparison, the same thin film transferred from a donor substrate to a receiving substrate according to the Smart Cut technology usually used, that is to say without the priming annealing and the second implantation described previously, presents a post-fracture surface roughness of between 80 and 90 angstroms (Ā) RMS and between 1000 and 1200 Å peak-to-valley (peak-to-valley) for point-to-point scanning surfaces of 10 * 10 microns. For step S11, more precisely, for an implantation dose of 5.75 1016 atoms / cm 2, there is applied, for example: a priming annealing slightly less than 1 minute at a temperature of 450 ° C. when the detachment annealing is carried out for a period of 10 minutes at 450 ° C., or - a priming annealing slightly less than 5 minutes at a temperature of 400 ° C., when the detachment annealing is carried out over a period of 50 minutes. minutes at 400 ° C., or a priming anneal slightly less than 6 hours at a temperature of 350 ° C., when the detachment annealing is carried out for a period of 60 hours at 350 ° C. The initiation annealing limited to 10% of the detachment annealing time makes it possible, as explained above, to make only a fraction of the first growth phase of the defects, namely that corresponding to the beginning of the transient process in which microcracks localized are partially formed and the growth / development of platelets above and below them is much more limited. The second hydrogen implantation at the localized growth zone of the microcracks will allow their growth to be promoted by increasing the quantity of hydrogen available for pressurizing them. During the detachment annealing applied later, the end of the transient process, described above, will thus be modified. The end of the nucleation of the microcracks, partially formed during the initiation annealing, then proceeds 14 differently. In fact, localized microcracks develop very rapidly and in a more lateral manner, while limiting their direct interactions with platelets located above or below their growth zone (less vertical deflection of the fracture line). A final, better localized fracture line is obtained in the initial microcrack area, which reduces the post-fracture roughness.

Example 2 This example which is described in connection with FIGS. 5A to 5E and 6 comprises the following steps: Step S20: hydrogen implantation in which a donor substrate 21 is subjected to ionic bombardment of H + hydrogen ions through the plane face 27 of the substrate having an oxide layer (SiO2) 22 under the same implantation conditions as previously described for step S10 in order to create a plate-like defect layer 23 parallel to the face 27 of the substrate delimiting, on the one hand, a thin film 24 in the upper region of the substrate 11 and, on the other hand, a portion 25 in the lower region of the substrate corresponding to the remainder of the substrate 21 (FIG. 5A) - Step S21: priming annealing at a temperature between 300 ° C and 7000C, the temperature usually used for detachment annealing. The duration of the priming anneal according to the present invention is less than 10% of the total time required to cause the detachment at the temperature used. This limitation of the duration of the priming annealing makes it possible to interrupt the growth of the defects (microcracks and platelets) before the end of the transient process and to avoid the breakdown of the silicon (FIG. 5B); Step S22: sequential helium implantation carried out by ionic bombardment 29 of He ions with a determined implantation energy as a function of the implantation energy used during step S20 so that the maximum of The concentration of implanted helium coincides with the maximum concentration of hydrogen implanted in step S20 (FIG. 5C). Those skilled in the art will be able to determine without difficulty the implantation energy required during the implantation of helium to obtain such a correspondence of the concentration maxima. The helium implantation is generally carried out with an implantation dose of between 1.1016 and 2.1016 atoms / cm 2; Step S23: bonding the donor substrate 21 with a receiving substrate 26 (FIG. 5D); Step S24: detachment annealing for causing fracture of the donor substrate 21 and the actual transfer of the thin film 24 onto the receiving substrate 26 (FIG. 5E). The thin film 24 has, after step 24, a post-fracture surface roughness of between 60 and 70 Å RMS and between 800 and 900 Å peak-to-valley amplitude (peak-to-valley) for point-to-point scanning surfaces of 10 * 10 microns.

As regards step S21, the examples of ignition annealing duration previously described for step S11 are here also applicable. The initiation annealing limited to 10% of the detachment annealing time makes it possible, as explained above, to make only a fraction of the first defect growth phase, namely that corresponding to the beginning of the transient process in which localized microcracks occur. are partially formed and the growth / development of platelets above and below them is much more limited. The second helium implantation at the localized growth zone of the microcracks will help promote their growth by providing a large amount of helium that will promote their pressurization. During the detachment annealing applied later, the end of the transient process, described above, will thus be modified. The end of the nucleation of the microcracks, partially formed during the priming annealing, then takes place differently. In fact, the localized microcracks develop very rapidly and in a more lateral manner, while limiting their direct interactions with platelets located above or below their growth zone (less vertical deflection of the fracture line). A final, better localized fracture line is obtained in the initial microcrack area, which reduces the post-fracture roughness.

Example 3

This example, which is described with reference to FIGS. 7A to 7E and 8, comprises the following steps: Step S30: implantation of hydrogen in which a donor substrate 31 is subjected to ionic bombardment of H + hydrogen ions through the face planar 37 of the substrate comprising an oxide layer (SiO2) 32 under the same implantation conditions as previously described for step S10 in order to create a layer of plate-like defects 33 parallel to the face 37 of the delimiting substrate, d first, a thin film 34 in the upper region of the substrate 31 and, secondly, a portion 35 in the lower region of the substrate corresponding to the remainder of the substrate 31 (Fig. 7A); Step S31: priming annealing at a temperature between 300 ° C and 700 ° C, the temperature usually used for detachment annealing. The duration of the initiation annealing according to the present invention is less than 10% of the total time required to cause the detachment at the temperature used. This limitation of the duration of the priming annealing makes it possible to interrupt the growth of the defects (microcracks and platelets) before the end of the transient process and to avoid the breakdown of the silicon (FIG. 7B); Step S32: sequential fluorine implantation carried out by ionic bombardment of F ions with a determined implantation energy as a function of the implantation energy used during step S30 so that the maximum concentration of implanted fluorine coincides with the maximum concentration of hydrogen implanted in step S30 (FIG. 7C). Those skilled in the art will be able to determine without difficulty the implantation energy required during implantation of the fluorine to obtain such a correspondence of the concentration maximums. Implantation of fluorine is carried out with an implantation dose of between 8.104 and 1.1015 atoms / cm 2; Step S33: bonding the donor substrate 31 with a receiving substrate 36 (FIG. 7D); Step S34: detachment annealing to cause fracture of the donor substrate 31 and the actual transfer of the thin film 34 to the receiving substrate 36 (FIG. 7E). The thin film 34 has, after step 34, a post-fracture surface roughness of between 60 and 70 Å RMS and between 800 and 900 Å peak-to-valley amplitude (peak-to-valley) for point-to-point scanning surfaces of 10 * 10 microns. As regards step S31, the examples of ignition annealing duration previously described for step S11 are here also applicable.

In step S32, the implantation can be carried out with other species such as in particular silicon, nitrogen and carbon. In general, step S32 consists in implanting in the substrate one or more species capable of curbing the growth of platelets which are at least above the peak of implanted hydrogen concentration. The species or species implanted in step 32 must be able to react with the implanted hydrogen, for example by creating bonds and / or interactions to form stable complexes with implanted hydrogen. In this case, the dissociation of hydrogenated species causing, by the formation of H2, the pressurization of the platelets is then delayed as long as the implanted hydrogen is not released from the stable complexes. Implantation of the species capable of reacting with the implanted hydrogen is carried out with an implantation energy chosen such that the peak of maximum implantation concentration is above or below the peak of maximum concentration of hydrogen for do not slow the growth of microcracks during the annealing of detachment. The embodiments of the transfer method according to the invention described above make it possible to obtain a post-fracture roughness on the surface of the transferred thin film and on the surface of the portion of the non-detached donor substrate between 60 and 70. RMS. This level of post-fracture roughness is much lower than that obtained during a transfer performed without the initiation annealing according to the invention. In fact, the post-fracture roughness level of a silicon substrate after detachment annealing is between 80 and 90 Å RMS for hydrogen implantation alone, and between 70 and 80 Å RMS for a hydrogen / helium co-implantation. . In general, it is also possible to replace steps S14, S24 and S34 which consist of a detachment annealing either by a mechanical detachment (application of a blade, a jet or a fluid), or by an annealing of partial detachment (ie limited in duration) which is completed by a mechanical detachment.15

Claims (13)

A method of transferring a layer (14) of a donor substrate to a recipient substrate (16) comprising: a) a first step of hydrogen ion implantation in the donor substrate (11) for forming a layer microcavities or platelets, b) a second ion implantation step, c) a step of bonding the face (17) of the donor substrate (11) 10 with a face of the receiving substrate (16), d) a detachment step to cause cleavage at the level of the layer of microcavities or platelets formed in the donor substrate), characterized in that it further comprises, after step a) and before step d), a heat treatment step initiator annealing performed at a temperature of between 300 ° C and 700 ° C and for less than 10% of the time required to cause cleavage at the layer of microcavities or platelets formed in the donor substrate at the temperature used during said step initiating annealing heat treatment. 2. Method according to claim 1, characterized in that step b) consists of an ion implantation of hydrogen in the donor substrate (11), the implantation being carried out with the same implantation energy as that used in step a). 3. Method according to the claim characterized in that step b) consists of an ion implantation of helium in the donor substrate (21), the implantation being performed with an implantation energy determined according to that used in step a) so that the zone comprising the maximum concentration of implanted helium coincides with the zone comprising the maximum concentration of hydrogen implanted during step a 4. Method according to claim 1, characterized in that step b) consists of an ion implantation in the donor substrate (31) of at least one species capable of reacting with the hydrogen implanted during step a) implantation being performed with an implantation energy different from that used in step a). 5. Method according to claim 4, characterized in that said implantation of at least one species capable of reacting with the implanted hydrogen is carried out with a determined implantation energy as a function of that used in step a). the zone comprising the maximum concentration of said at least one species is above the zone comprising the maximum concentration of hydrogen implanted in step a). 5 6. Method according to claim 4 or 5, characterized in that the species capable of reacting with the hydrogen implanted in step a) is chosen from at least one of fluorine, silicon, nitrogen and carbon. 7. Process according to any one of Claims 1 to 6, characterized in that the ionic hydrogen implantation during step a) is carried out with an implantation dose of between 4.1016 atoms / cm 2 and 1.1017 atoms. / cm2 and an implantation energy of between 10 and 210 keV approximately. 25 8. Method according to any one of claims 1 to 7, characterized in that the donor substrate (11; 21; 31) is a material selected from at least silicon, silicon germanium and germanium. 9. Process according to any one of claims 1 to 8, characterized in that the primer annealing heat treatment step is carried out at a temperature of 450 ° C for a duration of less than 1 minute, or at a temperature of temperature of 400 ° C for a period of less than 5 minutes, or at a temperature of 350 ° C for a period of less than 6 hours. 10. Process according to any one of claims 1 to 9, characterized in that the layer (14; 24; 34) has, after step d), a post-fracture surface roughness of between 60 and 70 Å RMS. and between 800 and 900 Å peak-to-valley amplitude for point-to-point scanning surfaces of 10 * 10 microns. 11. Process according to any one of claims 1 to 10, characterized in that step d) comprises annealing carried out at a temperature and for a time determined to cause cleavage at the layer of microcavities or platelets formed. in the donor substrate (11). 12. Method according to any one of claims 1 to 10, characterized in that step d) comprises the application of a mechanical force to cause cleavage at the layer of microcavities or platelets formed in the substrate donor (11). 13. The method of claim 12, characterized in that step d) further comprises a heat treatment.