Method for characterizing a donor substrate and / or implantation equipment

Abstract

The invention relates to a method for characterizing a donor substrate to determine whether this donor substrate is likely to trigger the formation of defects in a layer exfoliated by ion implantation. The characterization method comprises an X-ray diffraction analysis of an area on the front face of the donor substrate, after it has been implanted, to produce numerical incidence-intensity angle data defining a diffraction pattern. The method also includes a step of processing the diffraction pattern to provide an indicator quantifying the risk of triggering the formation of defects in an exfoliated layer of the donor substrate. Figure 4

Description

Title of the invention: Method for characterizing a donor substrate and / or implantation equipment. SCOPE OF THE INVENTION

[0001] The field of the invention is that of substrates formed by means of a thin-film transfer process, and more particularly a process comprising exfoliating the thin film from a so-called "donor" substrate by implanting light species. This process can notably be used to form a piezoelectric-on-insulator (POI) type structure. Such a structure finds application in the fields of microelectronics, microsystems, and photonics. It can be used to form radio frequency (RF) components or to constitute such components, in particular filters or resonators based on elastic wave components, for example, surface elastic wave components. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Document WO2020200986A1 proposes a method for manufacturing such a POI substrate that preserves the single-domain nature of the thin film. This document describes transferring a layer taken from a donor substrate comprising a piezoelectric material onto a support, via an implantation step of so-called "light" species (typically hydrogen and / or helium) in accordance with the principles of Smart Cut™ technology. Following this transfer, the extracted layer is processed in a finishing sequence comprising a heat treatment followed by a polishing step, this finishing sequence leading to the formation of the piezoelectric, single-crystal, single-domain thin film.

[0003] Document WO2023217845A1 relates to ion implantation equipment used to introduce light species into a donor substrate. In this document, the donor substrate consists of a thick layer of piezoelectric material deposited on a manipulator substrate. The advantages of such a donor substrate are described in document US2020186117. The implantation equipment comprises an ion source and an implantation wheel. The wheel includes a main disk driven in rotation under an ion beam produced by the source, and a plurality of supports on which the donor substrates are placed. The wheel includes a cooling circuit for cooling the supports. Each support has a receiving surface covered with a surface elastomer layer designed to receive a so-called "back" face of the donor substrate and to ensure satisfactory thermal conductivity with the cooled support.

[0004] The aim is generally to reduce the duration of the implantation step by increasing the ion beam current produced by the equipment, and in doing so, tends to increase the power delivered to the donor substrates and therefore their temperature. The equipment proposed by document WO2023217845A1 is configured to prevent or delay the phenomenon of thermal runaway which leads, through a progressive increase in the average temperature of the donor substrate, to deformation of this substrate and loss of intimate contact between its back face and the elastomer layer.

[0005] Application WO2024022723A1 reveals that defects can appear in the thin film after it has been transferred onto the POI substrate. These defects can, in particular, consist of "triangle defects," which take the form of ferroelectric domain inversion bars with triangular cross-sections ranging from 0.1 micron to 10 microns on a side. The bars emerge on the surface of the thin film and extend through its thickness, in some cases penetrating it. They are oriented in a direction antiparallel to the spontaneous polarization direction Ps of the piezoelectric thin film. These triangle defects can exhibit a density greater than 10A³ / cm² on the exposed surface of the thin film.

[0006] These defects have a significant impact on the performance of devices, for example acoustic filters, formed on and in POI substrates. The physical phenomena leading to their appearance are not fully understood, making it difficult to prevent or anticipate their development in the thin layer of the POI substrate. A final inspection plan is generally included in the manufacturing process of POI substrates, the inspection plan aiming to detect and reject POI substrates exhibiting such defects or an excessive density of such defects. OBJECT OF THE INVENTION

[0007] In light of this prior art, it appears desirable to have a means of anticipating the appearance of defects, and in particular triangular defects, in the thin layer of the POI substrate during the manufacturing process of this substrate. More generally, it appears desirable to have a means of characterizing a donor substrate and / or implantation equipment to determine whether the donor substrate or the implantation equipment is likely to trigger the appearance of defects in an exfoliated layer of the donor substrate. One object of the invention is to provide such a means. BRIEF DESCRIPTION OF THE INVENTION

[0008] To achieve this goal, the object of the invention proposes a characterization method aimed at determining whether a donor substrate is likely to trigger the appearance of defects in a layer exfoliated by ion implantation, the characterization process comprising: - a positioning step during which a rear face of the donor substrate is placed on a support of an implantation equipment; - an ion implantation step during which species are introduced into the donor substrate through a front face, then; - a measurement step comprising an X-ray diffraction analysis of an area of ​​the front face of the donor substrate, the measurement step producing numerical angle of incidence-intensity data defining a diffraction diagram; - a diffraction pattern processing step, the processing step providing an indicator quantifying the risk of triggering the appearance of defects in an exfoliated layer of the donor substrate.

[0009] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: - the diffraction pattern processing step includes the identification, in the diffraction pattern, of a main intensity peak and at least one secondary intensity peak; - the diffraction pattern processing step includes determining the relative position of one of the secondary intensity peaks with the main intensity peak; - the diffraction pattern processing step includes identifying the coordinates of the main intensity peak and the secondary intensity peak; - a coordinate of the secondary intensity peak is representative of the difference between the angle of incidence corresponding to the secondary intensity peak and the angle of incidence corresponding to the main intensity peak; - a coordinate of the secondary peak intensity corresponds to the intensity of the secondary peak intensity normalized by the intensity of the main peak intensity; - the characterization process further includes the comparison of one of the coordinates of the secondary intensity peak with a predetermined threshold, the indicator resulting from this comparison making it possible to discriminate whether the donor substrate is likely to trigger the appearance of defects in an exfoliated layer of this substrate; - the indicator is a numerical value representing the relative position of one of the secondary intensity peaks with respect to the main intensity peak, the indicator quantifying a risk of triggering the appearance of defects in an exfoliated layer of the donor substrate; - the processing step is implemented by a classifier configured by learning; - the positioning step includes the arrangement of a plurality of donor substrates on a plurality of supports of the implantation equipment, the ion implantation step includes the introduction of the species into the plurality of donor substrates, the measurement step includes the analysis by X-ray diffraction of an area of ​​the front face of the donor substrates and the processing step includes the provision of a plurality of indicators respectively associated with the supports; - the measurement step includes the symmetrical angular scanning of an area of ​​the front face of the donor substrate by an incident beam of monochromatic X-rays; - the angular deflection of the symmetrical angular scan is chosen to incorporate a primary intensity peak and a single secondary intensity peak in the diffraction pattern; - the area on the front face of the donor substrate, irradiated by X-rays, is not located in the center of the donor substrate; - the donor substrate comprises a piezoelectric material; - The defects likely to develop in the donor substrate are triangular defects. Brief description of the drawings

[0010] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which:

[0011] [Fig.1]

[0012] The [Fig.1] represents a POI substrate of the prior art;

[0013] [Fig.2]

[0014] Fig. 2 represents a method for manufacturing the POI substrate of Fig. 1;

[0015] [Fig.3]

[0016] Fig. 3 illustrates an X-ray diffraction measurement installation;

[0017] [Fig.4]

[0018] Fig. 4 represents diffraction diagrams respectively obtained by X-ray diffraction measurements on a plurality of implanted donor substrates;

[0019] [Fig.5]

[0020] Fig. 5 represents the distribution of the abscissa coordinates of the first secondary intensity peak of the implanted donor substrate diffraction diagrams, depending on whether the final substrates obtained using these donor substrates have or are free of triangular defects;

[0021] [Fig.6]

[0022] Figure 6 shows distributions similar to Figure 4 for, respectively, the abscissa of the second secondary intensity peak, the ordinate of the first secondary intensity peak, and the ordinate of the second secondary intensity peak. DETAILED DESCRIPTION OF THE INVENTION

[0023] We briefly recall at first the manufacturing steps of a substrate of the "on insulation" type in accordance with the principles of Smart Cut® technology, taking as an example the manufacturing of a final substrate 1 of the piezoelectric on insulation type, represented on [Fig.1].

[0024] With reference to figures 1 and 2, this process generally involves transferring a first crystalline piezoelectric layer 8, exfoliated from a donor substrate 5, onto a support 2, via an intercalated dielectric layer 3.

[0025] The crystalline piezoelectric material may be, for example, lithium tantalate or lithium niobate. The piezoelectric material has any crystal direction, for example, between 30° and 60°RY. The donor substrate 5 may be a bulk substrate made entirely of the piezoelectric material, as shown in [Fig. 2], or it may be a composite substrate consisting of a bulk portion, for example, silicon, on which rests a thick layer of piezoelectric material from which the first layer 8 is taken. The thick layer may be assembled and retained to the bulk portion by any possible technique, for example, by molecular adhesion or by means of an adhesive layer, for example, a polymer adhesive.

[0026] In some embodiments, the support 2 consists of a solid conductive or semiconducting substrate. In other embodiments, the support 2 comprises a basic semiconductor substrate, generally having a high resistivity greater than 1000 ohms·cm, provided with a surface charge-trapping layer. This trapping layer is disposed on the side of the first face of the support 2, which is intended to receive the thin film 4. The trapping layer may be made of polycrystalline silicon. In these embodiments, the intercalated dielectric layer 3 is in contact with the trapping layer and with the thin film 4.

[0027] According to the transfer technique based on the implantation of light species, and with reference to Figure 2b, the light species, typically hydrogen and / or helium in ionic form, are implanted in a front face 6 of the donor substrate 5 to form a buried weakening plane 7. The first layer 8 is thus defined between the weakening plane 7 and the first face 6 of the donor substrate 1.

[0028] As detailed in document WO2023217845A1 submitted in the introduction to this application, this implantation step comprises positioning the donor substrate 5 in the implantation equipment, during which a rear face of this substrate 5 is placed on a support of the equipment. Typically, such equipment comprises a wheel on which are arranged a plurality of supports for receiving, respectively, a plurality of donor substrates 5, for their collective processing. Each support is provided with an elastomeric layer to ensure satisfactory thermal contact with the substrate and to allow the dissipation of any heat that may accumulate there. Then, the implantation equipment is operated, and an ion beam having a determined energy and intensity is projected through the front face 6 of the donor substrates to introduce a determined dose of light species.

[0029] In a subsequent step, as shown in Figure 2c, this front face 6 of the donor substrate is assembled to an exposed face 6' of the support 2, here via an intercalated dielectric layer 3. By way of example, the intercalated dielectric layer 3 may comprise or be made of silicon oxide, silicon oxynitride, or silicon nitride. It may be formed on either or both of the donor substrate and the support 2 prior to their assembly.

[0030] The donor substrate 5 is then fractured at the level of the embrittlement plane 7, for example by means of a moderate heat treatment and / or the application of a mechanical force. The first layer 8 of the donor substrate 5 is then released to expose a free face 9 of this first layer 8, the other face 6 being in direct contact with the intercalated dielectric layer 3 of the support 2.

[0031] A remaining portion 5' of the donor substrate 5, after the removal of the first layer 8, can be reconditioned in order to remove a new layer, in a removal cycle similar to that which has just been described.

[0032] It is generally necessary to provide for the finishing of the first layer 8 transferred and transferred onto the support 2, to form a thin "useful" layer 4. These steps generally aim to improve the crystalline quality of the first layer 8 and its surface condition (for example its roughness) and, where appropriate, adjust its thickness to a target thickness.

[0033] As reported in the introduction to this application, this finishing may include a heat treatment step of the first layer 8, followed by a thinning step of this layer 8 to form the single-domain thin film 4.

[0034] The heat treatment step of the first layer 8 may correspond to exposing the free face 9 of the first layer 8 to a neutral atmosphere or one containing oxygen, raised to a temperature between 300°C and the Curie temperature of the ferroelectric material composing the first layer 8, and for a duration of between 30 minutes and 10 hours. The thinning step can be implemented by mechanochemical polishing or by dry etching. At the end of these manufacturing steps, the final substrate shown in [Fig. 1] is obtained.

[0035] In order to understand the origin of the defect in the thin film 4 described in the introduction, the applicant carried out numerous investigations. As part of this, it performed X-ray diffraction measurements on the donor substrate after the implantation step.

[0036] It should be noted that XRD technology (for "X-Ray Diffraction" in Anglo-Saxon terminology for "X-ray diffraction") is a widely used analytical technique for characterizing crystalline materials. Based on the interaction of X-rays with the atomic structure of crystals, this method makes it possible to determine the atomic arrangement, the dimensions of crystal lattices, the grain orientations, any structural deformations of a material, and other information on the internal structure of that material.

[0037] The basis of X-ray diffraction rests on Bragg's law, which describes how incident X-rays are reflected by the atomic planes of crystals. When the X-ray beam strikes a material, a portion is coherently scattered by the atoms, producing a characteristic diffraction pattern. This pattern depends on the crystalline nature of the material, the position of the atoms within an elementary cell of that material, and the spacing between the atomic planes. By measuring the angles and intensities of the diffracted rays, it is possible to reconstruct the parameters of the crystal lattice and identify the phase or structure of the analyzed material. A review of these principles and concrete examples of implementation can be found in the document by Harrington, GF, Santiso, J. Back-to-Basics tutorial: X-ray diffraction of thin films. J Electroceram 47, 141-163 (2021).

[0038] As part of the investigations carried out by the Applicant, and as illustrated in [Fig. 3], the front face 6 of the donor substrate 5 (i.e., the implanted surface) is irradiated with a monochromatic X-ray beam produced by a source S, and a detector D measures the intensity of the diffracted rays as a function of the angle of incidence co of the beam. The area irradiated by the beam is on the order of several mm². The irradiated area of ​​the front face 6 of the substrate 5 can be located anywhere on this front face, although it has been found that the measurement appears more reliable when this area is located on one side of this front face, rather than in its center.

[0039] The XRD analysis is implemented here by a 294° scan, also called a symmetric or coupled in-domain scan. According to this approach, the angle co (the angle of incidence between the source and the surface of the donor substrate) is maintained at half the angle 20 (the angle between the incident beam and the detector), as shown in [Fig. 3], during the angular scanning of the irradiated area. This collects numerical incidence angle-intensity data constituting a diffraction pattern, this pattern forming a unique imprint of the material.

[0040] Figure 4 shows examples of diffraction patterns obtained by XRD measurement of a plurality of donor substrates 5 after they have been implanted in accordance with the manufacturing process described above, in the same production batch. The donor substrates were therefore placed on separate supports, but exposed to the same beam of light species, having a single energy and intensity, and received the same dose of light species.

[0041] It is noted that each diagram exhibits a principal intensity peak PI representing the most significant diffraction direction. This principal intensity peak PI corresponds to the crystalline orientation of the piezoelectric material constituting at least part of the donor substrate. By convention, the principal intensity peaks PI are all located on the 0-degree abscissa in the diagrams of [Fig. 4]. It is noted that the intensity measurements recorded during the XRD measurement were normalized by the intensity of the principal intensity peak PI as represented in [Fig. 4], which compensates for emission variations from the source of the XRD measurement equipment.

[0042] In the diffraction diagrams reproduced in the figures, the coordinates of the points constituting these diagrams are therefore formed of an abscissa representing the angular deviation existing with the angle at which the main peak of intensity PI occurs and an ordinate representing the intensity normalized with respect to the intensity of this main peak PL. Of course, any other representation of the numerical data collected during the XRD measurement is possible.

[0043] The diagram also includes a flat area Zp for negative relative angles, and therefore to the left of the main intensity peak PI on the diagram shown in [Fig.4].

[0044] Finally, for even more negative relative angles, and to the left of the flat area Zp on the diffraction diagrams, there is an oscillation zone Zo comprising a plurality of secondary intensity peaks. This oscillation zone Zo is delimited, on each diagram, by two secondary intensity peaks P2 and P3 at its extremities, a first secondary intensity peak P2 to the right of the oscillation zone Zo, and a second secondary intensity peak P3 to the left of the oscillation zone Zo.

[0045] Each intensity peak can be located by its coordinates (t,i) in the diffraction diagram. As an illustration, the coordinates of abscissa t2 and ordinate i2 of a first secondary peak of intensity P2 of one of the diagrams are shown in [Fig.4].

[0046] The implanted donor substrates were then used to form a plurality of final substrates 1 according to the process described above. The free surfaces of these final substrates were inspected by scanning electron microscopy (SEM) to detect the presence of triangular defects. The final substrates were then classified into two groups, depending on whether or not they exhibited triangular defects.

[0047] Having performed this classification, the applicant discovered that the presence of triangular defects in a final substrate could be correlated with the diffraction pattern of the donor substrate used to form that final substrate. More specifically, the applicant realized that the presence or absence of triangular defects on a final substrate could be correlated with the position (i.e., the coordinates) of the first and second secondary intensity peaks of the diffraction pattern obtained on the donor substrate associated with that final substrate.

[0048] Thus, the results of this study are shown in [Fig. 5]. On the left side of this figure, a first boxplot illustrates the distribution of the abscissa coordinates of the first secondary peak of intensity P2 in the diffraction patterns of implanted donor substrates that led to the formation of final substrates free of triangular defects. On the right side of this figure, a second boxplot illustrates the distribution of the abscissa coordinates of the first secondary peak of intensity P2 in the diffraction patterns of implanted donor substrates that led to the formation of final substrates exhibiting triangular defects.

[0049] Recall that in a box plot, the box covers the data from the first quartile to the third quartile. The median line inside the box indicates the median of the data. The whiskers extend from the edges of the box to cover the remaining data.

[0050] Comparing the two box plots in this figure, we observe that these distributions of the abscissa coordinates of the first secondary peak of intensity P2 are statistically distinct from one another. In particular, we can compare an abscissa coordinate t2 of the first secondary peak of intensity P2 of a diffraction pattern of a donor substrate with a threshold value Vs to determine whether this donor substrate, if used in the manufacturing process to form a final substrate, will lead to a final substrate exhibiting (t2 > Vs) triangular defects or (t2 < Vs) not exhibiting such defects.

[0051] These results obtained are not limited to the t2 coordinate of the abscissa of the first secondary peak of intensity P2. Thus, [Fig. 6] represents distributions similar to [Fig. 4] for, respectively, the abscissa of the second secondary peak of intensity, the ordinate of the first secondary peak of intensity and the ordinate of the second secondary peak of intensity.

[0052] It therefore appears from these results that by comparing the relative position of a secondary intensity peak with respect to the main intensity peak in the diffraction diagram of a donor substrate implanted with a threshold position of this peak, it is possible to develop an indicator aimed at determining whether this donor substrate is likely to trigger the appearance of defects in a layer exfoliated by ion implantation.

[0053] Other analyses carried out by the Applicant show first of all that the measurement by X-ray diffraction of a donor substrate is repeatable: diffraction diagrams are produced very similar to each other, when this measurement is repeated on the same substrate.

[0054] Furthermore, these additional analyses showed that donor substrates placed on the same support of the implantation wheel and implanted in successive implantation stages exhibited very similar diffraction patterns, whereas these diffraction patterns could be very different from one support to another. Analysis of the diffraction pattern therefore makes it possible not only to characterize the donor substrate, to determine whether it will allow the formation of a final substrate free of triangular defects, but also to characterize the support of the implantation equipment.

[0055] When this equipment is fitted with several supports allowing the collective implantation of a plurality of substrates, it is then possible to order these supports, for example, according to the increasing value of the abscissa t2 coordinates of the first secondary peaks of intensity P2 of the diffraction patterns of the substrates respectively implanted on these supports. In this ordering, the supports are listed in ascending order of risk: the first are relatively unlikely, when used to implant a donor substrate, to generate defects in the final substrate. The last, on the contrary, are relatively very likely, when used to implant a donor substrate, to generate defects in the final substrate.

[0056] These additional analyses also showed that over time, the diffraction diagrams obtained on donor substrates placed during the implantation step on the same support tended to evolve, which encourages repeating the measurement regularly to identify these drifts.

[0057] The results just presented can be used to develop a treatment for the diffraction pattern, this pattern resulting from an X-ray diffraction analysis of a portion of the front face of the implanted donor substrate. The treatment step provides an indicator for quantifying the risk of triggering the appearance of defects in an exfoliated layer of a donor substrate. after forming a fragile plane buried in this substrate using implantation equipment.

[0058] This indicator can be used to characterize the implanted substrate itself or to characterize the implantation equipment, or a part thereof such as a support.

[0059] The processing step includes identifying, in the diffraction pattern, a primary intensity peak and at least one secondary intensity peak. More specifically, the diffraction pattern processing step includes determining the relative position of one of the secondary intensity peaks P2, P3 with the primary intensity peak P1.

[0060] In some cases, the processing step includes identifying the coordinates of the main peak of intensity PI and one of the secondary peaks of intensity P2,P3. One coordinate of the secondary peak of intensity P2,P3 may represent the difference between the angle of incidence corresponding to the secondary peak of intensity P2,P3 and the angle of incidence corresponding to the main peak of intensity PI. Another coordinate of the secondary peak of intensity P2,P3 may represent the intensity of the secondary peak of intensity P2,P3 normalized by the intensity of the main peak of intensity PI.

[0061] Regardless of how the coordinates of the secondary intensity peaks are expressed in the diffraction diagram, at least one of these coordinates can be compared with a predetermined threshold position of this peak.

[0062] The indicator resulting from this comparison makes it possible to discriminate whether the donor substrate and / or the implantation equipment is likely to trigger the appearance of defects in an exfoliated layer of this substrate or not. In this case, the indicator is binary in nature.

[0063] In other cases, the position of the secondary peak (or a numerical value representing this position) in the diffraction pattern constitutes the indicator itself. This position may correspond to one of the coordinates of a secondary peak, for example, the relative abscissa of this secondary peak of intensity P2,P3 in the diffraction pattern. The value of this position (which may be normalized, for example, between 0 and 1) quantifies the risk of triggering the appearance of defects in the exfoliated layer. The closer this indicator is to the threshold value above which defects are likely to appear, the greater the risk.

[0064] This approach is particularly useful for characterizing the supports of an implanting device in relation to one another with precision, when that device is equipped with a plurality of supports, as noted previously. The characterization process then makes it possible to associate a distinct indicator with each support.

[0065] Although a characterization method has been presented here that analytically decomposes the diffraction pattern during the processing step to identify the position of certain secondary peaks, other approaches for exploiting the numerical data of the diffraction pattern can naturally be envisaged. In particular, more global techniques can be used, for example, based on a pre-trained neural network or any other classifier configured by learning, to associate the donor substrate and / or the implant equipment with a risk indicator. The classifier can be trained using the data presented in the previous section, in particular data similar to those shown in Figures 5 and 6. The indicator provided by such a classifier can be binary or continuous.

[0066] In all cases, and regardless of how the processing step is implemented, the characterization process includes a processing step of a diffraction pattern, this processing step providing an indicator to quantify the risk of triggering the appearance of defects in an exfoliated layer of the donor substrate.

[0067] Similarly, the results presented in the previous section are obtained from the symmetrical angular scanning of an area on the front face of the donor substrate by an incident beam of monochromatic X-rays. However, in some cases, other types of measurements obtained by an incident X-ray beam can be used, without necessarily employing symmetrical scanning, which nevertheless remains the preferred approach.

[0068] To accelerate this symmetrical scanning measurement step, it is sufficient to choose the angular displacement to incorporate the main intensity peak and a single secondary intensity peak P2 into the diffraction pattern. Therefore, in this case, the angular displacement can be reduced without extending it to incorporate the second secondary intensity peak P3, thus shortening the acquisition time.

[0069] The characterization process can be exploited in multiple ways in a manufacturing process of a final substrate, a POI substrate in the example taken as an illustration.

[0070] It is of course possible to sort the donor substrates at the end of the implantation step of light species on the basis of the indicator provided by the characterization process, and to continue the manufacturing process only with the donor substrates which are not likely to trigger the appearance of triangle defects.

[0071] The indicator can also be used in a manufacturing process control plan. For example, the inspection of final substrates can be carried out only on those derived from donor substrates where the indicator suggests a risk of defect. In this case, it is no longer necessary to systematically Inspect all donor substrates. Alternatively, the inspection of the final substrates can be performed on those derived from donor substrates implanted on supports exhibiting the highest risk indicators. By measuring only the substrates with the most unfavorable indicators within a batch of ion implantation, the chances of detecting triangular defects, if present, are significantly increased compared to random sampling.

[0072] As also follows from the results presented in the preceding section, the characterization method can also be used in a maintenance plan for implanting equipment. For example, preventive maintenance of the implanting equipment can be initiated based on the indicator. This maintenance may, for instance, include replacing the elastomer layer covering each support of the implanting wheel. In this case, the indicator can be used to determine which support needs to be reconditioned in this way.

[0073] When the indicator results from comparing the position of a secondary intensity peak in the diffraction pattern with a threshold position of that peak, this threshold position may differ depending on the intended use of the indicator. In particular, different threshold positions may be used depending on whether the indicator is used for sorting donor substrates, during a final inspection, or for initiating maintenance of the implantation equipment.

[0074] Of course the invention is not limited to the modes of implementation described and alternative embodiments can be made without departing from the scope of the invention as defined by the claims.

[0075] In particular, the implantation equipment is by no means limited to equipment comprising a wheel on which a support or a plurality of supports are arranged. It may be any type of equipment capable of introducing species into a substrate to form a buried, fragile layer that will cause exfoliation of a layer from that substrate.

Claims

Demands

1. A characterization method for determining whether a donor substrate is likely to trigger the appearance of defects in an exfoliated layer by ion implantation, the characterization method comprising: - a positioning step during which a back face of the donor substrate is placed on a support of an implantation equipment; - an ion implantation step during which species are introduced into the donor substrate through a front face, then; - a measurement step comprising an X-ray diffraction analysis of an area of ​​the front face of the donor substrate, the measurement step producing numerical incidence-intensity angle data defining a diffraction pattern;- a diffraction pattern processing step, the processing step providing an indicator quantifying the risk of triggering the appearance of defects in an exfoliated layer of the donor substrate.

2. A characterization method according to the preceding claim, wherein the diffraction pattern processing step includes the identification, in the diffraction pattern, of a main intensity peak (PI) and at least one secondary intensity peak (P2,P3).

3. A characterization method according to the preceding claim, wherein the diffraction pattern processing step includes determining the relative position of one of the secondary intensity peaks (P2,P3) with the main intensity peak (PI).

4. A characterization method according to one of the two preceding claims, wherein the diffraction pattern processing step includes the identification of coordinates of the main intensity peak (PI) and the secondary intensity peak (P2,P3).

5. A characterization method according to the preceding claim in which a coordinate of the secondary intensity peak (P2,P3) is representative of the difference between the angle of incidence corresponding to the secondary intensity peak (P2,P3) and the angle of incidence corresponding to the main intensity peak (PI).

6. A characterization method according to one of the two preceding claims wherein a coordinate of the secondary intensity peak (P2,P3) corresponds to the intensity of the secondary intensity peak (P2,P3) normalized by the main intensity peak intensity (PI).

7. A characterization method according to any one of claims 4 to 6 further comprising comparing one of the coordinates of the secondary intensity peak (P2,P3) with a predetermined threshold, the indicator resulting from this comparison making it possible to discriminate whether the donor substrate is likely to trigger the appearance of defects in an exfoliated layer of this substrate or not.

8. A characterization method according to any one of claims 3 to 6 wherein the indicator is a numerical value representing the relative position of one of the secondary intensity peaks (P2,P3) with respect to the main intensity peak (PI), the indicator quantifying a risk of triggering the appearance of defects in an exfoliated layer of the donor substrate.

9. A characterization method according to any one of the preceding claims, wherein the processing step is implemented by a classifier configured by learning.

10. A characterization method according to any one of the preceding claims, wherein the positioning step comprises the arrangement of a plurality of donor substrates on a plurality of supports of the implantation equipment, the ion implantation step comprises the introduction of the species into the plurality of donor substrates, the measurement step comprises the X-ray diffraction analysis of an area of ​​the front face of the donor substrates and the processing step comprises the provision of a plurality of indicators respectively associated with the supports.

11. A characterization method according to any one of the preceding claims, wherein the measurement step comprises the symmetrical angular scanning of an area of ​​the front face of the donor substrate by an incident beam of monochromatic X-rays.

12. A characterization method according to the preceding claim in which the angular deflection of the symmetrical angular scan is chosen to incorporate a primary intensity peak (PI) and a single secondary intensity peak (P2) in the diffraction pattern.

13.

14.

15. A characterization method according to any one of the preceding claims, wherein the area of ​​the front face of the donor substrate, irradiated by X-rays, is not located at the center of the donor substrate. A characterization method according to any one of the preceding claims, wherein the donor substrate comprises a piezoelectric material. A characterization method according to any one of the preceding claims, wherein the defects likely to develop in the donor substrate are triangular defects.

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