FR2977074A1 - PROCESS FOR PRODUCING A SEMICONDUCTOR SUBSTRATE COMPRISING POROUS SILICON - Google Patents

Abstract

The invention relates to a method for manufacturing a semiconductor substrate (8), comprising - providing a donor substrate (1) semiconductor, - transforming the donor substrate (1) so that it comprises: o a porous support layer (2), made of a semiconductor material, and o a non-porous useful layer (3), and ▪ made of a semiconductor material, - treating said donor substrate (1), in such a way as to deform the porous support layer (2 ') in expansion or contraction, where said expansion induces stressing of the useful layer (3), into a useful layer (3') constrained, - to transfer at least a portion of the useful layer (3 ') constraint of the donor substrate (1) to a receiving substrate (8), - recycling the donor substrate (1), for the production of a constrained useful layer (3') having a constraint additional.

Description

GENERAL TECHNICAL FIELD The invention relates to a method of manufacturing a semiconductor substrate.

STATE OF THE ART Silicon-on-insulator substrates, known to those skilled in the art by the acronym SOI (silicon on insulator), are widely used in the microelectronics industry.

In particular, silicon substrates on insulator, known to those skilled in the art under the acronym sSO1 (strained silicon on insulator), are of major interest for the manufacture of electronic components, especially since sSO1 offer mobility increased electrons and holes, and therefore higher performance.

Of course, the constrained silicon must have the lowest possible defect density. A method of manufacturing constrained silicon, known from the state of the art, consists in epitaxializing a strained layer of silicon on a buffer layer, generally of varying composition in the thickness.

Another method of manufacturing constrained silicon consists in using a porous silicon layer in contact with a superficial silicon layer, and in stressing the porous silicon layer to induce a dilation or contraction stress in the silicon layer. superficial.

However, the known methods for producing sSO1, and more generally for stressed useful layers, have many drawbacks, insofar as they are costly and time consuming to implement. It is therefore necessary to provide a solution to meet the requirements of the microelectronics industry.

PRESENTATION OF THE INVENTION The invention proposes to overcome the aforementioned drawbacks. To this end, the invention proposes a method for manufacturing a semiconductor substrate, characterized in that it comprises: a first step of providing a semiconductor donor substrate; a second step of transforming the semiconductor substrate; donor substrate so that it comprises: a porous support layer, made of a semiconductor material, and a useful non-porous layer consisting of a semiconductor material, a third a step of treating said donor substrate, so as to deform the porous support layer by expansion or contraction, wherein said expansion induces stressing of the useful layer, into a constrained useful layer, a fourth step of transferring at least one a portion of the constrained useful layer of the donor substrate to a receiving substrate, a fifth recycling step comprising the implementation of the third step, from the substrate gives ur resulting from the fourth step, thus making it possible to further deform the support layer, in expansion or contraction, where said deformation induces additional stressing of the constrained useful layer, with a view to manufacturing a new receiving substrate comprising at least a portion of said constrained useful layer having undergone additional stressing. The invention is advantageously completed by the following characteristics, taken alone or in any of their technically possible combination: the fifth step further comprises the subsequent implementation of the fourth step of manufacturing a new receiving substrate comprising: at least a portion of the constrained useful layer, said strained useful layer having a higher stress than that of the constrained useful layer obtained before the fifth recycling step; the support layer and the useful layer consist of silicon; the useful layer, obtained after transformation of the donor substrate during the second step, has a thickness of between 10 and 100 nm; the first step comprises providing a donor substrate, which comprises a confinement structure comprising a semiconductor confinement layer, said confinement layer having a chemical composition different from the useful layer, and the fourth step of transferring to at least a portion of the strained useful layer of the donor substrate to the receiving substrate comprises the steps of: introducing ions into the donor substrate, bonding the donor substrate and the receiving substrate, subjecting the donor substrate and the receiving substrate to a heat treatment comprising raising the temperature, during which the confinement layer attracts the ions to concentrate them in said confinement layer, and o detaching the donor substrate from the receiving substrate by fracture at said confinement layer. The introduction of the ions into the donor substrate is carried out by immersing the donor substrate in a plasma comprising said ions; the step of transferring at least a portion of the useful layer constrained from the donor substrate to the recipient substrate comprises the steps of: creating an embrittlement zone in the donor substrate, bonding the donor substrate and the receiving substrate, and fracturing at said embrittlement zone to detach the donor substrate from the recipient substrate; the method consists in cyclically applying the second, third, fourth and fifth steps for the manufacture of a plurality of receiving substrates each comprising a non-porous constrained useful layer and constituted by at least one semiconductor material, starting from a donor substrate provided in the first step. The invention also relates to a method for manufacturing a semiconductor substrate, characterized in that it comprises: a first step of providing a semiconductor donor substrate; a second step of transforming the donor substrate; so that it comprises: a porous support layer, consisting of a semiconductor material, and a useful non-porous layer consisting of a semiconductor material, a third step of treating said donor substrate, so as to deform the porous support layer by expansion or contraction, said expansion inducing a stressing of the useful layer, into a constrained useful layer; a fourth step of transferring at least a portion of the layer; useful constraint of the donor substrate to a receiving substrate, - a fifth step of selecting a recycling pathway chosen from: o a first recycling path, comprising the implementation of the third step, starting from the donor substrate resulting from the fourth step, thus making it possible to further deform the support layer of said porous material, said deformation inducing an additional stressing of the constrained useful layer, with a view to the manufacture of a new receiving substrate comprising at least a portion of said constrained useful layer having undergone additional stressing, and o a second recycling pathway, comprising the polishing of the donor substrate resulting from the fourth step, in order to manufacturing a receiving substrate comprising at least a portion of the strained useful layer, said strained useful layer having a stress identical to that preceding said second recycling path. This method is advantageously completed by the following characteristics, taken alone or in any of their technically possible combination: the first and second recycling channels furthermore comprise the implementation of the fourth step of manufacturing a new receiving substrate comprising: o for the first recycling path, at least a portion of the constrained useful layer, said layer having a higher stress than before recycling, o for the second recycling path, at least a portion of the constrained useful layer said constrained useful layer having a stress identical to that preceding the recycling; the useful layer, obtained after transformation of the donor substrate during the second step, has a thickness of between 10 and 100 nm; the first step comprises providing a donor substrate, which comprises a confinement structure comprising a semiconductor confinement layer, said confinement layer having a chemical composition different from the stressed layer constituted by the third material, and the fourth step of transferring at least a portion of the strained useful layer from the donor substrate to the receiving substrate comprises the steps of: introducing ions into the donor substrate, bonding the donor substrate and the receiving substrate, and subjecting the donor substrate and the heat-treated receiving substrate comprising a temperature rise, wherein the confinement layer attracts the ions to concentrate them in said confinement layer, and detaching the donor substrate from the receiving substrate by fracture at said layer containment; the introduction of the ions into the donor substrate is carried out by immersion of the donor substrate in a plasma comprising said ions; the step of transferring at least a portion of the useful layer constrained from the donor substrate to the recipient substrate comprises the steps of: creating an embrittlement zone in the donor substrate, bonding the donor substrate and the receiving substrate, and 0 to fracture at said embrittlement zone to detach the donor substrate from the receiving substrate; the method consists in cyclically applying the second, third, fourth and fifth steps for the manufacture of a plurality of receiving substrates each comprising a non-porous constrained useful layer and constituted by at least one semiconductor material, starting from a donor substrate provided in the first step. The invention has many advantages, and in particular makes it possible to reduce the manufacturing time of strained layers having a good crystalline quality, as well as the associated manufacturing costs.

PRESENTATION OF THE FIGURES Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and which should be read with reference to the appended drawings, in which: FIG. schematic of a first embodiment of the method according to the invention; - Figure 2 is a schematic representation of an electrochemical anodizing process; FIG. 3 is an embodiment of a transfer step of a useful layer according to the invention; FIG. 4 is a diagram of the concentration of ions in the donor substrate in the case of implantation and diffusion of said ions; - Figure 5 is a schematic representation of a second embodiment of the method according to the invention.

DETAILED DESCRIPTION FIG. 1 shows an embodiment of a method of manufacturing a semiconductor substrate according to the invention. By semiconductor substrate is meant a substrate comprising at least one layer of semiconductor material.

The term "strained layer" refers to any layer of a semiconductor material whose crystallographic structure is stressed in tension or in compression, with respect to the natural crystallographic structure of the material. For example, it is possible to obtain strained layers during crystal growth, such as epitaxy, which modifies the crystal lattice, particularly in the growth direction. Conversely, the term "relaxed layer" refers to any layer of a semiconductor material that has a crystallographic structure free of any applied external stress, that is to say which has a mesh parameter identical to the mesh parameter. a layer of this material in massive monocrystalline form. The method comprises a first step E1 of providing a donor substrate 1 semiconductor. Advantageously, but not exclusively, the donor substrate 1 consists at least partly of silicon. It may also advantageously be germanium, or III-V type semiconductor materials (an alloy composed of an element of the third column of the periodic table of elements, and an element of the fifth column of the periodic classification of elements). In one embodiment, it is a solid donor substrate 1 formed of a semiconductor material, preferably chosen from the abovementioned materials. The method comprises a second step E2 of transforming the donor substrate 1 so that it comprises: a porous support layer 2 made of a semiconductor material, and a useful layer, This second step of transforming the donor substrate 1 advantageously comprises a step of electrochemical anodization of the donor substrate 1, illustrated in FIG. 2. Thus, the support layer 2 is for example a porous, and o constituted by a semiconductor material. formed of a material such as those mentioned above for the donor substrate 1, as well as the useful layer 3. The layer 2 and the layer 3 may consist of several semiconductor materials (alloy or superposition of several materials). In one embodiment, the support layer 2 and the useful layer 3 consist of the same material.

In this case, the donor substrate 1 is placed in an enclosure 10 comprising an electrolyte 11. The electrolyte 11 is for example a solution comprising hydrofluoric acid (HF). An anode 12 and a cathode 13, immersed in the electrolyte 11, are fed by a source of electric current 14. The donor substrate 1 is positioned so that the support layer 2 is turned towards the cathode 13, and so that the useful layer 3 is turned towards the anode 12. An electric current is applied between the anode 12 and the cathode 13 via the electric current source 14. This electric current is generally constant . The anodization is stopped when the desired thicknesses of the porous support layer 2 and the useful layer 3 have been reached. At the end of anodization, the donor substrate 1 is rinsed. Advantageously, the support layer 2 is p-doped, which makes it possible to accelerate the anodization. Advantageously, the useful layer 3, obtained after transformation of the donor substrate 1 consisting of said material, has a thickness of between 10 nm and a few hundred nanometers, in particular between 10 and 100 nm. The method comprises a third step E3 of treating said donor substrate 1 so as to deform the porous support layer 2 by expansion or contraction. During this step, internal stresses are generated in the porous support layer 2 which will make it possible to deform the porous support layer 2 'in expansion or contraction. A dilation corresponds to an expansion of the material, that is to say a tension deformation of the material, while the contraction corresponds to a retraction of the material, that is to say to a deformation in compression of the material. This deformation induces stressing of the useful layer 3 into a constrained useful layer 3 '. Indeed, the porous support layer 2 'thus deformed will induce stresses in the seed layer 3, causing stressing of the seed layer 3. The third step E3 may for example comprise a thermal oxidation step of the donor substrate 1 In this case, the donor substrate 1 is subjected to a heat treatment (for example between 200 ° C. and 800 ° C.) in an atmosphere which can be oxidizing (atmosphere comprising, for example, O 2, NO 2, etc.). This usually causes a dilation of the porous support layer 2 '. In another exemplary embodiment, the third step E3 may comprise nitriding, which in general makes it possible to generate compressive stresses and therefore contractive deformation of the support layer 2 '. The manufacturing method comprises a fourth step E4 of transferring at least a portion of the useful layer 3 'constrained 20 from the donor substrate 1 to a receiving substrate 8. In one embodiment, this fourth step comprises the steps of: creating a zone of embrittlement in the donor substrate 1, - bonding the donor substrate 1 and the receiving substrate 8, and 25 - making a fracture at said weakening zone 20, to detach the donor substrate 1 from the receiving substrate 8. The zone of embrittlement is created by implantation of ions, such as hydrogen or helium ions. This zone of embrittlement is generally created in the donor substrate 1. The transfer of at least a portion of the useful layer 3 'constrained from the donor substrate 1 to the receiving substrate 8 can be implemented by having constituted in the donor substrate an embrittlement zone, at which a fracture can be made to effect the transfer. The zone of weakness may have been formed by implantation in the donor substrate, as described above.

In this case, the ions are accelerated towards the surface of the donor substrate. The average penetration depth of the atoms is generally between 100 and 1 pm - this depth being determinable depending on the implanted species and the implantation energy. In the case of implantation, this has a peak implantation in the donor substrate. The implanted ions have a selected energy to allow them to pass through the donor substrate material. The peak of implantation depends on the energy of the ions. It may also have been constituted differently, for example as described below.

An embodiment of the fourth transfer stage E4 of the useful layer 3 'constrained from the donor substrate 1 to a receiving substrate 8 is thus described. This embodiment is illustrated in FIG. 3. In this embodiment, the donor substrate 1 further comprises a containment structure 23 comprising a confinement layer 25 formed of a semiconductor material. The role of this confinement layer 25 is to attract the ions introduced later into the donor substrate (for example by diffusion) during thermal annealing carried out on the donor substrate after this introduction, and during which the ions will preferentially migrate. to the confinement layer 25. The confinement structure 23 comprising the confinement layer 25 is generally obtained by epitaxy, and is formed during the first donor substrate formation step E1. The confinement structure may be disposed in the useful layer 3, or between the support layer 2 and the useful layer 3.

The epitaxy makes it possible to precisely control the thickness of the confinement layer 25, and makes it possible to obtain fine thicknesses for these. In addition, the epitaxy makes it possible to preserve the crystallinity of the useful layer 3 'to be transferred.

The material of the confinement layer is advantageously chosen from SiGe, doped or non-doped, or doped silicon. Other materials include germanium doped with boron, SiC doped with boron, or InGaN, AIGaN or InGaAs, AIGaAs. Doping with boron, arsenic or antimony may for example be carried out. Other materials and other dopants may be used. In all cases, the confinement layer is made of a material having a chemical composition different from the useful layer 3 'forced to transfer, which includes a difference at least in the proportion of the chemical elements (eg SiGe with a proportion in different germanium), or in the type of material (eg SiGe for layer 25 and Si for layer 3 '), or in the fact that the confinement layer has a higher doping than the layer 3' constrained to transfer (eg SiGe doped with boron for layer 25, and SiGe undoped or less doped for layer 3 '), or a combination of one or more of these differences. An advantageous embodiment consists in using a confinement layer consisting of a highly doped semiconductor material p. To enable the transfer of the strained useful layer 3 ', the fourth transfer step E4 comprises a step E41 for introducing ions into the donor substrate 1. These ions make it possible to create an embrittlement zone in the donor substrate 1 at which a fracture can be operated. It is advantageously hydrogen ions, or helium ions, or a combination of these ions. This introduction can be done in various ways.

Advantageously, the introduction of the ions 24 into the donor substrate 1 is carried out by diffusion of the ions 24 in the donor substrate 1 following the immersion of the donor substrate 1 in a plasma comprising said ions. It is specified that this introduction of ions 24 into the donor substrate 1 can be implemented by techniques other than diffusion, for example by implantation. The donor substrate 1 immersed in the plasma is subjected to electrical pulses. The positive ions present in the plasma are then accelerated towards the surface of the substrate where they are introduced. As the plasma surrounds the substrate, the whole surface receives ions at the same time. Another advantage of this introduction of ions is its ability to be applied on an industrial scale, as well as the reduced implementation time. Another advantage of this introduction of ions is that the zone of diffusion of the ions in the donor substrate is very concentrated, of the order of a few nanometers in thickness in the normal direction to the main faces of the substrate (for example between 10 nm and 200nm). The introduction of ions by plasma diffusion thus makes it possible to obtain good results in the transfer step, insofar as this technique makes it possible in particular to enrich the donor substrate 1 with ions with a low acceleration voltage (some 10 at 50kV) and at high dose (up to 10 + 18 at / cm2) in a shallow region (from a few tens of nanometers to about 200 nanometers as discussed above), which is not always accessible by an implantation technique. This is advantageous for subsequently transferring thin layers of the useful layer 3 'to be transferred. As explained later, this is advantageous for reducing the defects and roughness present in the transferred layer. Indeed, even when the region is accessible by implantation, the high energy of the ions in the implantation process leads to the introduction of crystalline defects in the useful layer 3 'to be transferred, making it more difficult to use later.

FIG. 4 illustrates the concentration profile of the ions 24 in the donor substrate as a function of the depth in the donor substrate 1, in the case of a diffusion (curve 26), and in the case of ion implantation. (curve 27).

The fourth transfer step further comprises a step E42 of bonding the donor substrate 1 and the receiving substrate 8. This bonding is achieved by contacting the free surfaces of the donor substrate and the receiving substrate. Most often, these surfaces have been previously cleaned to ensure the molecular adhesion of said surfaces. The fourth transfer step then comprises a step E43 of heat treatment of the donor substrate and of the receiving substrate, of subjecting them to a rise in temperature. If a confinement layer has been formed, this layer is made of material (s) adapted (s) to attract the ions introduced into the substrate to said confinement layer during this temperature rise heat treatment. Typical heat treatment temperatures are between 200 ° C and 700 ° C. For example, if the material of the confinement layer is silicon doped with boron, and the ions introduced into the donor substrate are hydrogen ions, the chemical interactions between boron and hydrogen will notably make it possible to attract the hydrogen ions in the confinement layer. Another factor of attraction of the ions can result from the difference of stress (in tension or compression).

Thus, during heat treatment of the donor substrate and the receiving substrate, the confinement layer attracts the ions to concentrate them in said confinement layer. Another function of this heat treatment may be to reinforce the bonding energy between the donor substrate and the receiving substrate.

The annealing is conducted so that different effects occur: - the bonding energy between the donor substrate and the receiving substrate is increased, - the ions are concentrated in the confinement layer until reaching a critical concentration, - these Ions create cavities, which will coalesce, the pressure in these cavities increases to cause a fracture in the confinement layer, which allows to separate the donor substrate from the receiving substrate. These four effects can be obtained during a single thermal annealing, or during separate individual thermal annealing. Thus, the step following the heat treatment is a step E44 of detaching the donor substrate 1 from the receiving substrate 8 by fracture at said confinement layer 25. The useful layer 3 'constraint is thus transferred. The receiving substrate 8 is then treated by cleaning and polishing (CMP or other), to remove unwanted layers of layers. In particular, this is the residual confinement layer that has been transferred with the semiconductor strain layer. The donor substrate 1 is also treated, for recycling, if necessary, in the context of a transfer of a new useful layer 3 'stress. An advantage of the transfer method implementing the constitution of a confinement layer is that the fracture is very localized, and occurs almost exclusively or only at the level of the confinement layer. Typically, post-fracture AFM roughnesses obtained without a confinement layer are of the order of 3 to 6 nm, whereas the confinement layer makes it possible to reduce this roughness to values of the order of 0.5 to 1 nm. Thus, the propagation of defects towards the strained semiconductor layer to be transferred is avoided. Indeed, in the case of a conventional transfer by ion implantation and fracture at a zone of embrittlement without the use of a confinement layer, it is common for defects to appear in the substrate after fracture. . This is notably due to the extensive presence of ions in the substrate, which induces a loosely localized fracture, and therefore a higher roughness. The useful layer 3 'semiconductor stress transferred in accordance with this method therefore has a reduced roughness. For example, in the case of a donor substrate 1 comprising a useful layer 3 'of silicon to be transferred and a confinement layer 23 made of silicon doped with boron, it is possible to obtain a roughness of the silicon layer transferred from 5 Angstroms in RMS value. In addition, it is often necessary to transfer useful layers 3 'semiconductor stresses having a thin thickness (for example between 20nm and 500nm). Indeed, it is known that there is a compromise between the stress present in the layer and the thickness of said layer. For a given constraint, there is a thickness beyond which the stress is released by appearance of defects.

This embodiment of the sixth step therefore makes it possible in particular to transfer useful layers 3 'semiconductor stresses having a thickness of between 10 and 200 nm. Advantageously, a confinement layer having a thickness of between 2 and 20 nm is used. The finer the confinement layer, the more localized the fracture will be. For example, a confinement layer with a thickness of about 4 nm will make it possible to confine the fracture in this zone. In view of the small thickness of the confinement layer, it does not disturb or very little the mesh parameter of the donor substrate.

In general, it is possible to use a structure 23 for confinement, comprising a confinement layer 25 as previously described, and two protective layers arranged in contact and on both sides of the confinement layer, each these protective layers being formed of a semiconductor material of chemical composition different from the material of the confinement layer. The term "different chemical composition" means that the materials are different, or different proportions of chemical elements, and / or that they have a doping with a different dopant. The transfer is carried out with the containment structure in a manner similar to that previously described for the confinement layer. These protective layers make it possible to further limit the propagation of defects resulting from the fracture. These play in particular the role of protective shield of the useful layer 3 'semiconductor stress to be transferred, and confine defects likely to propagate to the useful layer 3' to be transferred following the fracture in the layer of containment. Examples of embodiments include, for example, but not limited to, for the protective layers: - material of the protective layers: Si (, _,) Ge, material of the confinement layer: Si (II) Gey (advantageously, the difference between x and y is at least 3 ° / 0, preferably greater than 5 ° / 0 or even 10 ° / 0), SiGe doped with boron or silicon doped with boron. We can also mention the case where the protective layers are made of SiGe and the boron doped silicon confinement layer, as is the case where the protective layers are SiGe and the confinement layer is Ge doped with boron. protective layer material: Silicon, material of the confinement layer: Si (II) Gey, SiGe doped with boron or silicon doped with boron; material of the protective layers: germanium, material of the confinement layer: SiGe doped with boron, or silicon doped with boron, or germanium doped with boron, or SiGe; Material of the protective layers: SiGe, material of the confinement layer: SiC doped with boron; - material of the protective layers: AIGaN, material of the confinement layer: doped InGaN (Si, Mg) or not; protective layer material: AIGaAs, material of the doped InGaAs confinement layer (Si, Zn, S, Sn) or not.

Advantageously, the materials of the protective layers are also adapted to attract the ions introduced into the donor substrate to the confinement layer, during a heat treatment for raising the temperature of said donor substrate, for example doped SiGe or not to attract hydrogen ions.

In addition, or alternatively, it is advantageous for at least one of the protective layers to be an etching stop layer, made of a material allowing selective chemical etching of the protective layer vis-à-vis the useful layer 3 'constituted constraint. This is generally a protective layer in contact with the useful layer 3 'stress. This makes it possible to implement a step of selectively etching the protective layer present on the receiving substrate 8 after the detachment of the donor substrate 1. In addition, or alternatively, one of the protective layers is a barrier layer. chemical etching, consisting of a material allowing a selective chemical etching of the protective layer vis-à-vis the support layer 2 '. The method may comprise a step of selectively etching the protective layer present on the donor substrate after fracture, thereby reusing the donor substrate. It is advantageous to use SiGe protective layers with a boron-doped silicon confinement layer, and with a useful 3 'constrained silicon transfer layer. At the end of the fourth step E4, a receiving substrate 30 is obtained comprising at least a portion of the useful layer 3 'constrained. Advantageously, and whatever the embodiment chosen for the transfer, the fourth step comprises a preliminary step of forming an oxide layer 18 in contact with the useful layer 3 'constrained to the donor substrate 1, the bonding of the donor substrate 1 and the receiving substrate 8 being made at the level of said oxide layer 18. Alternatively, or in addition, the receiving substrate 8 itself comprises an oxide layer at which bonding with the donor substrate 1 is performed. The receiving substrate 8 is then treated in a conventional manner, according to the desired applications. In general, it undergoes a finishing treatment including polishing. Advantageously, the useful layer 3 'is made of silicon, and the receiving substrate 8 is, at the end of the fourth step, a silicon substrate constrained on insulator. At the end of the fourth step, the method also comprises a step of recycling the donor substrate 1. In a first embodiment, illustrated by the arrow E5 in FIG. 1, it is a fifth step E5, comprising the implementation of the third step E3, from the donor substrate 1 from the fourth step, thereby further deforming the porous support layer 2 ', in dilation or contraction, said deformation inducing a additional stressing of the useful layer 3 'constraint, for the manufacture of a new receiving substrate 8 comprising said stressed layer 3' having been subjected to additional stressing. This recycling step therefore aims to produce a useful layer 3 'stress having a greater stress than the useful layer 3' 25 stress said non-porous material obtained at the end of the fourth step before recycling. It is therefore a recycling to increase the stress of the useful layer (stress layer of non-porous material). Advantageously, the fifth step further comprises a new implementation of the fourth step, making it possible to manufacture a new receiving substrate 8 comprising at least a portion of the constrained useful layer 3 ', the said constrained useful layer 3' having a greater stress. higher than that of the stressed layer of said non-porous material obtained before the recycling step. Thus, this new implementation of the fourth step consists in transferring at least a portion of the constrained useful layer 3 ', having undergone additional stressing, to a new receiving substrate, according to the previously described embodiments. The fifth recycling step may include other additional steps. In one embodiment, the fifth step of recycling the donor substrate 1 comprises a step of polishing the 3 'constrained useful layer belonging to the donor substrate 1. In effect, following the transfer of a portion of the stressed layer 3' towards the receiving substrate 8, roughness may be present on the surface of this layer, which may be reduced or eliminated by polishing 15 implemented during recycling. Alternatively, or in addition, the fifth recycling step may comprise an epitaxial step, making it possible to increase the thickness of the useful layer 3 'constrained. This step consists of growing the material of the useful layer 3 'on this layer to increase the thickness. This step may prove useful in the case where the thickness of the constrained useful layer 3 ', present in the donor substrate 1 intended to be recycled, is no longer sufficient to envisage the creation of a new receiving substrate comprising part of this layer. The epitaxy of said material therefore makes it possible to increase the thickness of this useful layer 3 '. Advantageously, the manufacturing method is applied cyclically, that is to say that the second, third, fourth and fifth steps are repeated, for the manufacture of a plurality of recipient substrates 8 each comprising a useful layer 3 semiconductor stress, from a donor substrate 1 provided at the first step. In a second embodiment of the manufacturing method according to the invention, it comprises, in addition to the first, second, third and fourth steps previously described, a fifth step of selecting a recycling path. It should be noted that all the features described above, and relating to the first, second, third and fourth steps are applicable for this embodiment of the manufacturing process. These characteristics are therefore not repeated again. This fifth stage of selection of a recycling path makes it possible to choose between two recycling paths: a first recycling path E5 and a second recycling path E6.

The first recycling path E5 corresponds to the fifth recycling step described above in the first embodiment of the manufacturing method. The first recycling path E5 thus comprises the implementation of the third step, starting from the donor substrate 1 resulting from the fourth step, thus making it possible to further deform the support layer 2 'of said porous material, said deformation inducing a setting under additional constraint of the useful layer 3 'constraint, for the manufacture of a new receiving substrate comprising at least a portion of the strained useful layer 3' having been subjected to additional stressing.

This recycling path has been detailed in the first embodiment. All the features previously described for this recycling path are applicable here. The second recycling path E6 comprises the polishing of the donor substrate 1 resulting from the fourth step, with a view to the production of a receiving substrate comprising at least a portion of the useful layer 3 'constrained, said layer having a stress identical to that preceding said second recycling path. Thus, in this second recycling path, the stress of the useful layer 3 'of the non-porous material is kept constant, unlike the first recycling path. This second recycling path is illustrated in FIG. 5. This second recycling path therefore advantageously comprises, in addition to the abovementioned polishing, the repetition of the fourth step to transfer again at least a portion of the useful layer 3 'constrained. Thus, thanks to the process according to the invention, the recycling is very flexible and makes it possible either to recycle the donor substrate 1 in order to manufacture a useful layer of semi-conductor having additional stress, or to recycle the donor substrate 1 into to manufacture a useful semiconductor layer with a stress identical to that preceding the recycling. Advantageously, the first and second recycling channels 10 further comprise the implementation of the fourth step of manufacturing a new receiving substrate 8. For the first recycling path, the new receiving substrate then comprises at least a portion of the strained useful layer 3 ', said layer having a higher stress than before recycling. For the second recycling path, the new receiving substrate then comprises at least a portion of the constrained useful layer 3 ', said layer having a stress identical to that preceding the recycling. Advantageously, the useful layer is made of silicon, and the receiving substrate 8 is a constrained silicon substrate on insulator. Advantageously, the first recycling path includes a step of polishing the constrained useful layer 3 '. Advantageously, the first recycling path and / or the second recycling path comprise an epitaxial step, making it possible to increase the thickness of the useful layer 3 'constrained. Advantageously, the method comprises the sequence of cyclically applying the second, third, fourth and fifth steps (the fifth step being the step of selecting the recycling path) for the manufacture of a plurality of recipient substrates comprising each a useful layer 3 'of semiconductor, from a donor substrate 1 provided in the first step.

It is of course possible to apply the first recycling path to one cycle iteration, and to another iteration of the cycle the second recycling path. In a third embodiment, the manufacturing method comprises, in addition to the first, second, third and fourth steps, only the second recycling path previously described. As can be seen, the invention offers the possibility of performing a plurality of transfer of strained layers from the same substrate comprising a layer of a porous semiconductor.

The invention has many advantages also in terms of costs, delays, flexibility. The invention finds many applications for the manufacture of useful layers constrained in the microelectronics industry.

Claims (15)

REVENDICATIONS1. A method of manufacturing a semiconductor substrate (8), characterized in that it comprises: - a first step (E1) of providing a semiconductor donor substrate (1), - a second step (E2) consisting of transforming the donor substrate (1) so that it comprises: a porous support layer (2) made of a semiconductor material and a useful nonporous layer (3) and composed of a semiconductor material, - a third step (E3) of treating said donor substrate (1), so as to deform the porous support layer (2 ') by expansion or contraction, where said expansion inducing a setting under constraint of the useful layer (3), in a useful layer (3 ') constrained, - a fourth step (E4) of transferring at least a portion of the useful layer (3') stress from the donor substrate (1) to a receiving substrate (8), - a fifth recycling step (E5) comprising o the implementation of the third step, from the donor substrate (1) from the fourth step, thereby further deforming the support layer (2 '), dilation or contraction, o said deformation inducing additional stressing of the layer useful (3 ') constraint, for the manufacture of a new receiving substrate (8) comprising at least a portion of said strained useful layer (3') having undergone additional stressing. 30 2. The method of claim 1, wherein the fifth step (E5) further comprises the subsequent implementation of the fourth step (E4) of manufacturing a new receiving substrate (8) comprising: - at least a portion of the strained useful layer (3 '), - said strained useful layer (3') having a higher stress than that of the strained useful layer (3 ') obtained before the fifth recycling step (E5). 3. Method according to one of claims 1 or 2, wherein the support layer (2,2 ') and the useful layer (3, 3') consist of silicon. 4. Method according to one of claims 1 to 3, wherein the useful layer (3), obtained after transformation of the donor substrate (1) in the second step (E2) has a thickness between 10 and 100nm. 15 5. Method according to one of claims 1 to 4, wherein: the first step (E1) comprises the provision of a donor substrate (1), which comprises a confinement structure (23) comprising a confinement layer ( 25) semiconductor, said confinement layer (25) having a chemical composition different from the useful layer (3), and - the fourth step (E4) of transferring at least a portion of the useful layer (3 ') strain from the donor substrate (1) to the recipient substrate (8) comprises the steps of: introducing (E41) ions (24) into the donor substrate (1), bonding (E42) the donor substrate (1) and the receiving substrate (8) subjecting (E43) the donor substrate (1) and the receiving substrate (8) to a heat treatment comprising a temperature rise, during which the confinement layer (25) attracts the ions (24) to concentrate them in said confinement layer (25), and detach (E44) the substrate gives ur (1) of the receiving substrate (8) by fracture at said confinement layer (25). 6. The method of claim 5, wherein the introduction of the ions (24) in the donor substrate (1) is performed by immersing the donor substrate (1) in a plasma comprising said ions. 7. Method according to one of claims 1 to 4, wherein the step of transferring at least a portion of the useful layer (3 ') stress of the donor substrate (1) to the receiving substrate (8) comprises the steps comprising: - creating a zone (20) of embrittlement in the donor substrate (1), - bonding the donor substrate (1) and the receiving substrate (8), and - operating a fracture at said zone (20) of embrittlement, for detaching the donor substrate (1) from the receiving substrate (8). 8. Method according to one of claims 1 to 7, consisting in cyclically applying the second, third, fourth and fifth steps for the manufacture of a plurality of receiving substrates (8) each comprising a useful layer (3 ') constrained non porous and made of at least one semiconductor material, from a donor substrate (1) provided in the first step. 9. A method of manufacturing a substrate (8) semiconductor, characterized in that it comprises: - a first step (E1) of providing a donor substrate (1) semiconductor - a second step (E2) ) of transforming the donor substrate (1) so that it comprises: o a porous support layer (2) made of a semiconductor material, and o a useful layer (3), - non-porous and made of a semiconductor material; a third step (E3) of treating said donor substrate (1) so as to deform the porous support layer (2 ') by expansion or contraction, wherein said dilation inducing stressing of the useful layer (3) into a useful layer (3 ') constrained, - a fourth step (E4) of transferring at least a portion of the useful layer (3') constrained to the donor substrate ( 1) to a receiving substrate (8), - a fifth selection step (E5, E6) of a selected recycling path p armi: o a first recycling path (E5), comprising the implementation of the third step, from the donor substrate (1) from the fourth step, thereby further deforming the support layer (2 ') said porous material, said deformation inducing an additional stressing of the useful layer (3 ') constraint, for the purpose of manufacturing a new receiving substrate (8) comprising at least a portion of said useful layer (3') constraint having undergone additional stressing, and o a second recycling path (E6), comprising polishing the donor substrate (1) from the fourth step, for the production of a receiving substrate comprising at least a portion of the useful layer (3 ') constrained, said useful layer (3') stress having a stress identical to that preceding said second recycling path. 30 The method according to claim 9, wherein the first and second recycle ways further comprise the implementation of the fourth step of manufacturing a new receiving substrate (8) comprising: - for the first channel of recycling, at least a portion of the useful layer (3 ') stress, said layer having a higher stress than before recycling, - for the second recycling path, at least a portion of the useful layer (3') constraint , said useful layer (3 ') stress having a stress identical to that preceding the recycling. 11. Method according to one of claims 9 or 10, wherein the useful layer (3) obtained after transformation of the donor substrate (1) in the second step (E2), has a thickness between 10 and 100nm. The method according to one of claims 9 to 11, wherein: the first step (E1) comprises the supply of a donor substrate (1), which comprises a confinement structure (23) comprising a confinement layer ( 25), said confinement layer (25) having a chemical composition different from the stressed layer (5) made of the third material, and - the fourth step (E4) of transferring at least a portion of the useful layer ( 3 ') stress of the donor substrate (1) towards the recipient substrate (8) comprises the steps of: introducing (E41) ions (24) into the donor substrate (1), bonding (E42) the donor substrate (1) and the receiving substrate (8) subjecting (E43) the donor substrate (1) and the receiving substrate (8) to a heat treatment comprising a rise in temperature, during which the confinement layer (25) attracts the ions (24). ) to concentrate them in said confinement layer (25), and detaching (E44) the donor substrate (1) from the receiving substrate (8) by fracture at the level of said confinement layer (25). 13. The method of claim 12, wherein the introduction of the ions (24) into the donor substrate (1) is performed by immersing the donor substrate (1) in a plasma comprising said ions. The method according to one of claims 9 to 11, wherein the step of transferring at least a portion of the useful layer (3 ') constrained from the donor substrate (1) to the receiving substrate (8) comprises the steps of: - creating a zone (20) of embrittlement in the donor substrate (1), - bonding the donor substrate (1) and the substrate (8) receiver, and - operate a fracture at said zone (20) embrittlement, for detaching the donor substrate (1) from the receiving substrate (8). 15. Method according to one of claims 9 to 14, of cyclically applying the second, third, fourth and fifth steps for the manufacture of a plurality of receiving substrates (8) each comprising a useful layer (3 ') constrained non-porous and consisting of at least one semiconductor material, from a donor substrate (1) provided in the first step.