Semiconductor substrate for laser debonding, and manufacturing method

Abstract

The invention relates to a substrate (SUB) suitable for releasing a layer to be transferred by light irradiation of a separation layer, the substrate comprising: a carrier (WafCar) and, in this order from a top surface (TopCar) of the carrier (WafCar), a first nitride layer (SiN1Car); the separation layer (TiN1Car) made of titanium nitride; an encapsulating nitride layer (SiN3Car) covering the carrier; and a first nitride layer (SiN1Car); the separation layer (TiN1Car); an encapsulating nitride layer (SiN3Car); and the layer (TL) to be transferred, wherein the encapsulating nitride layer (SiN3Car) covers the separation layer (TiN1Car) such that the separation layer (TiN1Car) is encapsulated between the first nitride layer (SiN1Car) and the encapsulating nitride layer (SiN3Car).

Description

SEMICONDUCTIVE SUBSTRATE FOR LASER PEEL-ON AND MANUFACTURING PROCESS FIELD OF INVENTION

[0001] The present invention relates to the field of the semiconductor industry and proposes a semiconductor substrate designed to allow laser peeling of a thin, possibly single-crystal, layer. CONTEXT OF THE INVENTION

[0002] The semiconductor industry is increasingly using thin film transfer techniques, which consist of forming a thin film on a first substrate called a "donor substrate", then transferring the thin film formed onto a second substrate, called a "carrier substrate" or "manipulation substrate".

[0003] The donor substrate can be chosen for its compatibility with the conditions for thin film formation, or the thin film can be formed within the mass of the material forming this donor substrate.

[0004] The carrier substrate is adapted to the processing of this thin film, for example by being compatible with subsequent manufacturing steps, or even by carrying a structure onto which the thin film will be integrated. Ultimately, a fabricated thin film comprising the thin film, or only a portion of it remaining after the manufacturing steps, must be transferred onto a third substrate, called the "receiving substrate".

[0005] Among the thin film transfer techniques used in the semiconductor industry, laser peeling (LLO) has emerged as an effective method for separating a film or stack of films, or one or more thin films, from a carrier substrate using a layer, called a separation layer or gap layer, whose separation or degradation is triggered by thermal energy from light irradiation, such as laser irradiation.

[0006] Typically, the separation layer is laser-irradiated through the carrier substrate. The separation layer must absorb sufficient light at the laser wavelength to promote separation or degradation (for example, by locally melting the separation layer or causing its dissociation into elementary components), while the carrier substrate must be substantially transparent at that wavelength. A balance between laser power, laser wavelength, and material selection (for both the separation layer and the carrier substrate) must be achieved to allow separation while protecting the layer(s) to be transferred from the impact of energy dissipation due to light interaction processes: heat transfer due to absorption in the separation layer or direct absorption of some of the laser irradiation by the layer(s) to be transferred.

[0007] US patents 2014 / 327049, US 2023 / 207661, CN 113 097 124 each describe a method for manufacturing semiconductor devices involving separation facilitated by laser irradiation.

[0008] However, there are other requirements regarding the quality and reliability of the conventional process described above, as well as its cost. Furthermore, the materials traditionally used to form the separation layer on the carrier substrate may limit the processes that can be applied to the thin film.

[0009] A first object of the invention is a substrate adapted to release a transfer layer by light irradiation from a separation layer, the substrate comprising: a support and, in this order from a top surface of the support: a first nitride layer covering at least a top surface and a bottom surface of the support, the top surface being opposite the bottom surface; the separation layer, the separation layer being formed of titanium nitride; an encapsulating nitride layer; and the transfer layer, in which the encapsulating nitride layer covers the separation layer so that the separation layer is encapsulated between the first nitride layer and the encapsulating nitride layer.

[0010] The fact that the separation layer is encapsulated and protected from the atmosphere allows the carrier substrate to be subjected to processes that would otherwise degrade the separation layer. The nitride layers also prevent the separation layer from coming into direct contact with oxide layers, which could be contaminated by oxygen and ultimately lead to the degradation of the separation layer, thus impairing its biodegradability.

[0011] According to other non-limiting features of the invention, considered individually or in any technically possible combination: the separation layer can be in direct contact with the first nitride layer and the encapsulating nitride layer; the first nitride layer and the nitride encapsulating layer can be formed of silicon nitride;

[0012] - the substrate may further comprise: a light-blocking layer between the separation layer and the nitride encapsulation layer, the light-blocking layer and the separation layer being capable of substantially absorbing light of the same wavelength; and a second nitride layer between the separation layer and the light-blocking layer;

[0013] - the separation layer and the light-blocking layer can be formed from titanium nitride, and the first nitride layer, the second nitride layer and the nitride encapsulation layer are formed from silicon nitride;

[0014] - the layer to be transferred can be made of silicon carbide or silicon;

[0015] - the first nitride layer, the encapsulating nitride layer and, where applicable, the second nitride layer are substantially free of oxygen, and preferably have an oxygen content of less than 1% by mass, and more preferably less than 0.1% by mass;

[0016] - a bonding oxide layer can be interposed between the encapsulating nitride layer and the layer to be transferred;

[0017] - the substrate and the separating layer can be respectively substantially transparent and substantially absorbent to light of a given wavelength, so that the layer to be transferred can be separated from the substrate when the separating layer is irradiated by light of the given wavelength through the substrate during a light irradiation peeling operation; and

[0018] - the encapsulating nitride layer can cover a lateral edge of the separation layer.

[0019] The fact that the first nitride layer covers both the upper and lower surfaces of the substrate has the advantage of preventing, or at least limiting, warping of the substrate, particularly during processes requiring heating. Consequently, the operations to be applied to the layer to be detached, which include bonding this layer to a receiving substrate, are simplified. It is indeed preferable to process and handle devices that are flat rather than those that exhibit warping.

[0020] Another advantage of the first nitride layer is that it prevents contamination of the carrier substrate by the material forming the separation layer, which can be made of TiN and whose function is to enable a laser peeling process to release the layer to be transferred. This effect is more pronounced when the first nitride layer covers both the upper and lower surfaces of the support substrate, and even more pronounced when the first nitride layer completely covers the support substrate, including its edge.

[0021] The light-blocking layer has the advantage of preventing damage to the layer to be transferred during a subsequent irradiation step of the separation layer through the support substrate during a layer separation step, because it absorbs at least some of the radiating light that can pass through the separation layer instead of letting that part irradiate the layer to be transferred.

[0022] A second object of the invention is a method for manufacturing a substrate capable of releasing a transfer layer by light irradiation from a separation layer, the method comprising, in this order: the steps of: forming a first nitride layer on a top surface and a bottom surface of a support, the top surface being opposite the bottom surface; forming a separation layer on the top surface of the support; forming an encapsulating nitride layer on the top surface of the support, and forming a transfer layer on the top surface of the support with the separation layer between the two, the step of forming the separation layer and the step of forming the encapsulating nitride layer being carried out in such a way that the separation layer is encapsulated between the first nitride layer and the encapsulating nitride layer.

[0023] Such a method makes it possible to obtain the substrate of the first object of the invention, with its advantages.

[0024] According to other non-limiting features of the invention, considered individually or in any technically feasible combination:

[0025] - at least one of the steps in the formation of the first nitride layer and the encapsulating nitride layer may use a substantially conformal deposition method, preferably low-pressure chemical vapor deposition;

[0026] - at least the separation layer formation step can use plasma-assisted chemical vapor deposition or physical vapor deposition;

[0027] - the first nitride layer formation step completely covers the upper and lower surfaces of the support with the first nitride layer, the upper surface being opposite the second surface;

[0028] - the separation layer formation step includes the following steps: bonding a donor substrate to the upper surface of the support with the separation layer interposed between the donor substrate and the upper surface of the support; and removal of a portion of the donor substrate.

[0029] Other features and advantages of the invention will become apparent from the detailed description of the invention that follows, with reference to the accompanying figures, in which:

[0030] Laillustre un process de fabrication de un substrat selon la invention;

[0031] Laillustre the typical geometries of a silicon wafer seen in plan view;

[0032] Laillustre les geometries typiques d’une wafer de silicon en section cross ;

[0033] Laillustre a substrate obtained by the manufacturing process of the;

[0034] Laillustrates a manufacturing process using the substrate of the.

[0035] DETAILED DESCRIPTION OF A SPECIFIC EMBODIMENT OF THE INVENTION

[0036] First embodiment of the invention

[0037] A first embodiment of the invention is explained with the aid of Figures 1 to 5, which illustrate (i) fabrication of a SUB semiconductor substrate designed to allow laser peeling of a TL layer to be transferred, generally a layer of active material such as single-crystal silicon, and (ii) a method of transferring the TL layer onto a receiving substrate.

[0038] Laillustrates the steps of a PR1 fabrication process of a SUB semiconductor substrate designed to allow laser peeling of a TL layer to be transferred onto a Waf receiving substrate Rec .

[0039] A Waf load-bearing substrate Car is prepared in steps 10 to 18, a Waf donor substrateDonest préparé aux étapes 20 à 24, une couche du substrat donneur est transférée sur le substrat porteur et finalisée aux étapes 30 et 32.

[0040] Waf support slice preparation Car

[0041] In step 10, a Waf carrier substrate Car is provided. The carrier substrate can be a substrate conventionally used in the semiconductor industry, such as a semiconductor wafer, for example a silicon wafer, preferably a raw silicon wafer, a bare silicon wafer, on which no layer has been intentionally deposited. The carrier substrate has a top surface Caret une surface inférieure BotCarqui forment deux surfaces planes parallèles, comme illustré à la(A1).

[0042] In any case, the Waf carrier substrate Car is preferably substantially transparent to light of a wavelength belonging to the infrared spectrum. The Waf carrier substrate Carpeut être considéré comme substantiellement transparent si 90% ou plus de la lumière ayant une longueur d'onde donnée dans le spectre infrarouge, par exemple 2 µm, est transmise à travers le substrat porteur WafCar.

[0043] In step 12 following step 10, an internal oxide layer Ox Caris preferably formed at least on the upper surface, and possibly on the lower surface, of the supporting substrate. The Ox1 oxide layer Carpeut être formée par oxydation thermique du substrat porteur, pour former une couche d'oxyde de silicium d'une épaisseur comprise entre 10 nm et 200 nm. Grâce à ce processus, la couche d'oxyde OxCarcouvre la quasi-totalité du substrat porteur, ce qui inclut les surfaces supérieure et inférieure ainsi que ainsi que le bord du substrat porteur reliant ces deux surfaces, comme illustré à la(A2).

[0044] In step 14 following step 12, a first layer of SiN1 nitride Car can be formed, at least on the upper and lower surfaces of the support substrate. The first layer of SiN1 nitride Car can be formed by depositing 10 nm to 200 nm of silicon nitride by low-pressure chemical vapor deposition (LP-CVD). Low-pressure chemical vapor deposition can be used to achieve conformal coating of a substrate. In this case, the formation of the first SiN1 nitride layer CarA conformal deposition technique such as LP-CVD allows the first nitride layer to be formed in such a way as to cover almost the entire support substrate, including the top and bottom surfaces as well as the edge of the support substrate connecting these two surfaces, as illustrated in (A3). The use of such a deposition technique makes it possible to limit or eliminate substrate warping: nitride layers are generally subjected to stresses, and the formation of the first SiN1 nitride layer Car The first layer of SiN1 nitride, applied to both sides of the substrate, balances the stresses and prevents warping. Car may be in direct contact with the Ox oxide layer Car .

[0045] The internal oxide layer Ox Car and the first layer of SiN1 nitride Carforment ensemble une couche isolante couvrant chacune de la surface supérieure TopCaret de la surface inférieure BotCardu substrat porteur WafCar.

[0046] In step 16 following step 14, a TiN1 separation layer Car, a second layer of SiN2 nitride Car and a light-blocking TiN2 layer Car are successively formed on the upper surface Top Car of the support substrate. In this embodiment, the light-blocking layer is TiN2 Carest en contact direct avec la deuxième couche de nitrure SiN2Car, la deuxième couche de nitrure SiN2Carest en contact direct avec la couche de séparation TiN1Car, et la couche de séparation TiN1Carest en contact direct avec la première couche de nitrure SiN1Car. La couche de blocage de lumière TiN2Carest avantageusement utile pour bloquer la lumière utilisée pendant une opération de décollage du laser et pour protéger la couche TL à transférer

[0047] The TiN1 separation layer Car and the TiN2 light-blocking layer CarThey have practically the same light absorption characteristic: they are designed to absorb or block the same wavelength of light. To this end, they are both made from the same material, titanium nitride in this embodiment. They do not necessarily have the same thickness and do not necessarily absorb or block all of the incident infrared light. It is sufficient that they absorb, for example, 30% or more of a given wavelength of infrared light, for example, between 1 µm and 5 µm, for example, a wavelength of 2 µm. The SiN2 layer Car separates the two TiN1 layers Car and TiN2 Car to enable them to fulfill their respective functions independently.

[0048] The TiN1 separation layer Carcan be formed over a thickness of 10 nm to 200 nm by deposition of titanium nitride TiN by plasma-assisted chemical vapor deposition (PE-CVD) or by physical vapor deposition (PVD).

[0049] The second layer of SiN2 nitride Car can be formed over a thickness of 10 nm to 200 nm by deposition of silicon nitride SiN by plasma-enhanced chemical vapor deposition (PE-CVD).

[0050] The TiN2 light-blocking layer Car can be formed over a thickness of 10 nm to 200 nm by deposition of titanium nitride TiN by plasma-assisted chemical vapor deposition (PE-CVD) or by physical vapor deposition (PVD).

[0051] Figure (A4) illustrates the stack described above.

[0052] In step 18 following step 16, an encapsulating SiN3 nitride layer Car is formed on the light-blocking TiN2 layer Car The encapsulating SiN3 nitride layer Carcan be formed in direct contact with the light-blocking TiN2 layer Car .

[0053] The encapsulating SiN3 nitride layer Car can be formed over a thickness of 10 nm to 500 nm by deposition of silicon nitride SiN by PE-CVD or by low pressure chemical vapor deposition (LP-CVD) to form a conformal layer.

[0054] Preferably, the methods used to form the TiN1 separation layer Car , the second layer of SiN2 nitride Car and the TiN2 light-blocking layer Car are more directive than the methods used to form the encapsulating SiN3 nitride layer Car , which leads to the geometry illustrated by (A5), the encapsulating SiN3 nitride layer Car covering the edges of the TiN1 separation layer Car , of the second layer of SiN2 nitride Car and the TiN2 light-blocking layer CarIndeed, the method used to form the encapsulating SiN3 nitride layer Car leads to the formation of layers with better conformability than the methods used to form the TiN1 separation layer Car , the second layer of SiN2 nitride Car and the TiN2 light-blocking layer Car .

[0055] However, the invention is not limited to a TiN1 layer Car completely embedded between the SiN1 layers Car and SiN3 Car , the edges of the TiN1 layer Car being included as illustrated in (A5). As long as the upper and lower surfaces of the TiN1 layer Car are embedded between the SiN1 layers Car and SiN3 Car , and therefore protected from external chemical contamination, it is sufficient to implement the aspect of the invention relating to the protection of the TiN1 layer Car More specifically, the TiN1 layer Car is considered to be integrated between the SiN1 layersCar and SiN3 Car even if the edges of the TiN1 layer Car are not coated with SiN3 Car This can be the case when the SiN3 layer deposition method Car is not sufficiently compliant to cover said edges.

[0056] Furthermore, the first layer of SiN1 nitride Car , the encapsulating SiN3 nitride layer Car and the second layer of SiN2 nitride Car are essentially oxygen-free, meaning their oxygen content is low enough not to significantly degrade TiN1 Car and TiN2 Car when subjected to high temperatures (for example between 700°C and 1100°C), and preferably have an oxygen content of less than 1% by mass, and more preferably less than 0.1% by mass.

[0057] Therefore, the TiN1 separation layer Car and the TiN2 light-blocking layer Carare completely isolated from the atmosphere and from any layer containing oxygen that could significantly damage the TiN1 layers Car and TiN2 Car This is important because (i) processes subjecting these layers to high temperatures (e.g., between 700°C and 1100°C) can, in the presence of oxygen, transform titanium nitride (TiN) into titanium oxide (TiO), (ii) the functions of the TiN1 layers Car and TiN2 Car are to absorb or block infrared light at a later stage (see below, description in relation to the) and (iii) titanium oxide is transparent to infrared light.

[0058] We observe that subjecting the TiN1 layers Car and TiN2 Car High temperatures in the presence of oxygen render them unable to perform their functions.

[0059] However, the encapsulation of TiN1 layers Car and TiN2 Carlayers of silicon nitride isolate the TiN1 layers Car and TiN2 Car oxygen and therefore advantageously allows these layers to be used at higher temperatures than in the past without them losing their infrared light absorption properties.

[0060] Preparation of the Waf donor platelet Don

[0061] In step 20, a Waf donor substrate Don is provided. The donor substrate can be a substrate conventionally used in the semiconductor industry, such as a semiconductor wafer, such as a silicon wafer, preferably a raw silicon wafer, i.e., a bare silicon wafer without any layers having been intentionally deposited on it. The donor substrate has a top surface Donet une surface inférieure BotDonqui forment deux surfaces planes parallèles, comme illustré à la(B1).

[0062] In step 22 following step 20, a layer of Ox oxide Donis formed at least on the upper and lower surfaces of the donor substrate. The Ox oxide layer Donpeut être formée par oxydation thermique du substrat donneur, pour former une couche d'oxyde de silicium d'une épaisseur comprise entre 10 nm et 500 nm lorsque le substrat donneur est formé de silicium. Par ce processus , la couche d'oxyde OxDoncouvre pratiquement tout le substrat donneur, qui comprend les surfaces supérieure et inférieure ainsi que le bord du substrat donneur reliant ces deux surfaces, comme illustré par la(B2).

[0063] It is also possible to use other types of donor substrates, in combination with a conformal deposition method such as LP-CVD to form an Ox oxide layer Don covering the donor substrate.

[0064] In step 24, to define a layer of the material forming the donor wafer and prepare its separation from the rest of the donor wafer, an ion implantation process (ImP) is implemented: a light ion species, hydrogen (H₂), is implanted. + and / or helium He + is introduced into the Waf donor substrate Don through the top surface Donpour former un plan de fragilisation ou de fragilisation FrglDonà l'intérieur du substrat donneur. Le plan de fragilisation est sensiblement parallèle à la surface supérieure TopDon, comme l'illustre la(B3). Le volume du substrat donneur compris entre la surface supérieure TopDonet le plan de fragilisation Frgl définit une couche mince TL qui sera ultérieurement transférée sur le substrat porteur, puis sur un substrat récepteur. La couche mince TL sera détachée du reste du substrat donneur WafDonpar la technologie Smart CutTM.

[0065] The introduction of ions can correspond to hydrogen implantation, that is, ion bombardment of the upper surface. Donof the donor substrate with hydrogen ions. Generally, the type, dose, and energy of the implanted species are chosen based on the desired thickness of the layer to be transferred and the physicochemical properties of the donor substrate. These parameters can be adjusted to define the thickness of the thin film (TL) between 5 nm and 2 µm.

[0066] The carrier wafer and the donor wafer can independently exhibit the geometric characteristics of the Waf wafers illustrated in Figures 2 and 3. Lamontre shows that the Waf wafer generally has a substantially circular edge Edg with at least one flat Fla ((A)) or a notch Not ((B)) which can be used to orient the wafer according to its crystallographic characteristics, if applicable.

[0067] Laillustrates the Waf slice in a cross-sectional view, showing different edge profiles, with a rounded edge at (A) and a beveled edge at (B). The edge profiles connect to a top surface. ( Waf ) of the Waf slice to a lower Bot surface ( Waf ) of the Waf bracket.

[0068] Assembly and finalization of the SUB substrate

[0069] Once the donor wafer and the carrier wafer have been prepared, they are bonded together in a gluing step 30: the layers covering the upper surfaces of the Waf donor substrate Don and the Waf carrier substrate Carsont mises en contact intime et subissent une adhésion moléculaire et / ou un collage électrostatique entre elles, comme mentionné par exemple dans la demande de brevet français publiée sous le numéro 2 914 492.

[0070] In this embodiment, a nitride-oxide bond is formed between the encapsulating nitride layer SiN3 Car and the Ox donor oxide layer Don Thus, the SiN3 layer CarIt can serve a dual purpose: protecting the underlying layers and facilitating bonding. The surfaces in close contact can be prepared by cleaning, brushing, drying, polishing, or plasma activation, as is common practice in the field. The resulting assembly comprises the following layers, stacked in this order: Waf carrier substrate Car , internal oxide layer Ox Car , first layer of SiN1 nitride Car , TiN1 separation layer Car , second layer of SiN2 nitride Car , TiN2 light-blocking layer Car , SiN3 nitride coating layer Car , Ox donor layer Don and Waf donor substrate Don, comme illustré par la(C1).

[0071] As is known, during a molecular adhesion process, the exposed surfaces of the insulating layer and the donor substrate, which are perfectly clean, flat, and smooth, are brought into intimate contact to promote electrostatic bonding or the development of molecular bonds, such as van der Waals or covalent bonds. The two bodies are then joined without the use of an adhesive. The bonding process may include the application of a low-temperature heat treatment (e.g., between 50 and 300°C, typically 100°C) to heal crystalline defects in the donor substrate and sufficiently increase the bonding energy to allow for a possible subsequent thinning step or other processing.

[0072] In step 32 following step 30, a splitting process is carried out to split the Waf donor substrate Don at the level of the Frgl weakening plane so as to leave the TL layer fixed to the Waf carrier substrate Car. La structure obtenue après la scission est le substrat semi-conducteur SUB illustré par la(C2).

[0073] More specifically, after the 30th bonding step, the TL layer is detached from the rest of the Waf donor substrate Don by fracture at the level of the weakening plane Frgl and is thus transferred to the load-bearing substrate Waf Car. Cette étape de détachement peut impliquer l'application d'un traitement thermique à une température comprise entre 350°C et 1000° pour détacher la couche TL du substrat donneur et achever son transfert sur le substrat porteur WafCar. En alternative ou en complément du traitement thermique, cette étape peut consister à appliquer une lame ou un jet de fluide gazeux ou liquide, ou toute autre force mécanique sur le plan de fragilisation Frgl.

[0074] After step 32, which produces the SUB structure illustrated by (C2), a stabilizing heat treatment can optionally be applied to the SUB substrate in a post-fractionation step. The stabilizing heat treatment heals crystalline defects in the TL thin film and helps consolidate the bond between this TL thin film and the carrier substrate, for example, by heating the Sub substrate to a temperature between 300°C and 800°C for a period of 30 minutes to 10 hours. This heat treatment is preferably carried out by exposing the free face of the TL thin film to a neutral gaseous atmosphere ( ).

[0075] Step 32 may include a smoothing step of the free surface of the TL layer, for example by CMP (Chemical Mechanical Polishing) and / or wet etching. At this stage, the SUB semiconductor substrate may be ready for any processing intended by the user of the SUB substrate. In particular, heat treatment at a temperature above 700°C may be considered because the titanium nitride layers are insulated from oxygen by the silicon nitride layers.

[0076] Alternatively, the semiconductor substrate can be shipped to the user without the smoothing step having been performed, allowing the user to carry out a smoothing step of their choice. This is because the SUB semiconductor substrate is intended for use by various parties, and the manufacturing unit where it was produced will generally differ from the manufacturing unit where the active material layer will be processed to form a functional semiconductor device or a component thereof.

[0077] Furthermore, as an alternative to the formation of a weakening plane and the fracture of the donor substrate at this plane, the donor substrate can be thinned after assembly with the carrier substrate, for example by etching, grinding, and / or chemical-mechanical polishing (CMP). This thinning can be used to remove the donor substrate entirely or only partially, for example, to achieve the situation illustrated by (C2).

[0078] Depending on the profiles of the edges of the Waf carrier slice Car and the Waf donor slice Donet de leur alignement à l'étape 30, les couches TiN1Car, SiN2Car, TiN2Caret SiN3Carpeuvent présenter une protubérance qui dépasse des couches OxDonet TL lorsqu'elles sont vues en coupe transversale du substrat SUB, comme illustré par la(C2). On peut également dire que les bords latéraux des couches OxDonet TL sont en retrait par rapport aux bords latéraux des couches TiN1Car, SiN2Car, TiN2Caret SiN3Car.

[0079] Example of using the SUB substrate

[0080] Laillustrates the steps of a PR2 manufacturing process consisting of transferring, by laser detachment, a TL layer to be transferred from the SUB substrate to a Waf receiving substrate Rec .

[0081] Here, the TL layer is made of monocrystalline silicon, obtained from the Waf donor substrateDon which was a single-crystal silicon wafer. The TL layer is suitable for applications in fields such as SRAM (Static Random Access Memory), HBM (High Bandwidth Memory) or logic circuits, and is compatible with FEOL (Front End Of Line) processes.

[0082] At step 100, the Waf receptor substrate Rec is provided. The Waf substrate Recpeut être n'importe quel type de substrat plat ayant une surface lisse, tel que le substrat couramment utilisé dans l'industrie des semi-conducteurs : Si, SiC, saphir, verre, AlN ou toute combinaison de ces matériaux. Le substrat récepteur WafReca une surface supérieure TopRec, comme l'illustre la(A1). En tout état de cause, le substrat récepteur doit être compatible avec un processus de collage pour le transfert d'une couche mince TL et avec l'utilisation prévue d'un dispositif à fabriquer.

[0083] At step 200, the SUB substrate obtained by the PR1 manufacturing process is supplied, as illustrated by (B1).

[0084] In step 300, the thin TL layer is bonded to the top surface. Rec of the Waf receptor substrate Rec, comme illustré à la(C1). Le même processus que celui de l'étape 30 de collage direct peut être mis en œuvre. Bien qu'elle ne soit pas représentée sur la, une couche (monocouche ou multicouche) favorisant le collage entre la couche mince TL et le substrat récepteur WafRecpeut éventuellement être formée. Par exemple, dans le cas d'un collage oxyde-oxyde, une couche d'oxyde peut être déposée sur la couche mince TL et une couche d'oxyde peut être formée sur la surface supérieure TopRecdu substrat récepteur WafRec.

[0085] After the fabrication of the SUB substrate and before step 300, the TL thin film may have undergone various fabrication steps to form a structure to be transferred onto the Waf receiving substrate Recincluding heat treatment between 800°C and 1100°C.

[0086] In step 302 following step 300, light is irradiated through the TiN1 separation layer Car through the Waf carrier substrate Car , as illustrated by the light irradiations Irr A and Irr B in the, representing two portions of a light irradiation for explanatory purposes. The light irradiations Irr Aet IrrBproviennent d'une même source lumineuse et ont une même longueur d'onde comprise entre 1 µm et 5 µm.

[0087] By absorbing the energy of light irradiation Irr A , the TiN1 separation layer Car is heated locally and degrades, releasing the thin TL layer. By mechanical traction Trac, the Waf carrier substrate Car is separated from the Waf receptor substrate Rec, laissant la couche mince TL liée au substrat récepteur WafRec. La fonction de la couche de séparation TiN1Carest de permettre la séparation de la couche TL du substrat porteur WafCar.

[0088] Light irradiation Irr B crosses the TiN1 separation layer Caret peut être bloquée par la couche de blocage de lumière TiN2Car. La fonction de la couche optionnelle de blocage de lumière TiN2Carest de protéger la couche de transfert TL d'une irradiation lumineuse nocive susceptible de dégrader la structure formée par la couche TL ou la couche TL elle-même. Cette structure confine également au moins partiellement l'énergie de l'irradiation lumineuse incidente entre la couche de blocage de lumière TiN2Caret le substrat porteur WafCar.

[0089] It is known that titanium nitride can be used as a separating layer in a laser delamination process using a laser with a wavelength in the infrared range (approximately 2 µm for TiN, for example between 1 µm and 5 µm), and that monocrystalline silicon is transparent to infrared light. A combination using a monocrystalline wafer as a carrier substrate (Waf) Car and a titanium nitride as a separating layer TiN1 Caret couche de blocage de lumière. Dans ce cas, le nitrure de titane TiN se décompose en diazote N2gazeux et en Ti liquide, détachant l’une de l'autre les deux couches prenant en sandwich TiN1Car.

[0090] La(C2) illustrates the result of the separation of the Waf carrier substrate Car of the Waf receptor substrate Recà l'étape 302 : des parties irrégulières de la couche de séparation TiN1Carpeuvent subsister, et il est généralement préférable d'éliminer les couches OxDon, SiN3Car, TiN2Car, SiN3Car, les restes de TiN1Caret la couche facultative qui est favorable au collage entre la couche mince TL et le substrat récepteur WafRec, afin d'accéder à la couche mince TN.

[0091] In step 304, after step 302, a step is performed to clear the TL layer of the remaining layers above it, for example by CMP (Chemical Mechanical Polishing) and / or wet etching. Figure (C3) illustrates the Waf receiving substrate Rec after step 304.

[0092] The Waf carrier substrateCar Separated from the thin TL film, it can be recycled for reuse. The first layer is SiN1 nitride. Carempêche avantageusement les éléments de la couche de séparation de contaminer le substrat porteur WafCar, ce qui contribue à simplifier le traitement en vue du recyclage et à réduire le coût global du processus.

[0093] Second embodiment of the invention

[0094] A second embodiment of the invention is illustrated by [illegible text] and is very similar to the first embodiment, except for the nature of the donor substrate and its preparation before being bonded to the carrier wafer: in this embodiment, Waf Don is a silicon carbide wafer.

[0095] Unlike step 22 of the first embodiment, in the second embodiment, step 22 is carried out by depositing a silicon oxide layer with a thickness between 10 and 500 nm on the upper surface. Don of the Waf donor substrate Don, par dépôt chimique en phase vapeur assisté par plasma, comme illustré par la(B2).

[0096] Next, the PR1 and PR2 manufacturing processes can be executed as in the first embodiment.

[0097] In this embodiment, the TL layer can be used, for example, for applications in power electronics or to form an interposer in photonic integrated circuits.

[0098] The figures in this document are not necessarily to scale. Some features and components may be shown in an exaggerated manner relative to other components or in a somewhat schematic form, and some details of conventional elements may not be shown for the sake of clarity and conciseness.

[0099] Of course, the invention is not limited to the embodiments described and other embodiments may be used without departing from the scope of the invention as defined by the claims.

[0100] In particular, the described embodiments each employ irradiation to separate the transfer layer TL from its carrier substrate Waf Car , these irradiations being carried out through this carrier substrate Waf Car These modes are advantageous because they avoid or limit irradiation of the transfer layer TL, but irradiation through the carrier substrate Waf. Car but through the receiving substrate Waf Rec is also conceivable, meaning that the irradiation source can be located on the receiving substrate side of the SEP layer designed to absorb this irradiation. More generally, the invention is not limited to processes in which the Irr irradiation is carried out through the Waf carrier substrate. Car , and therefore it is not necessarily transparent to the wavelength of Irr irradiation

Claims

1. Substrate (SUB) adapted to release a transfer layer (TL) by light irradiation of a separating layer (TiN1 Car ), the substrate comprising: - a support (Waf Car ) and, in that order, from a higher surface (Top Car ) support (Waf) Car ) :- a first layer of nitride (SiN1 Car ) covering at least one upper surface (Top Car ) and a lower surface (Bot Car ) of the support (Waf Car ), the upper surface (Top Car ) being opposite to the lower surface (Bot Car ) ;- the separation layer (TiN1 Car ), the separation layer (TiN1 Car ) being formed of titanium nitride; - an encapsulating nitride layer (SiN3 Car ) ; and- the transfer layer (TL), in which the encapsulating nitride layer (SiN3 Car ) covers the separation layer (TiN1 Car ) so that the separation layer (TiN1 Car) is encapsulated between the first nitride layer (SiN1 Car ) and the encapsulating nitride layer (SiN3 Car ).

2. The substrate (SUB) according to claim 1, in which the separation layer (TiN1 Car ) is in direct contact with the first nitride layer (SiN1 Car ) and the encapsulating nitride layer (SiN3 Car ).

3. The substrate (SUB) according to claim 1 or 2, in which the first nitride layer (SiN1 Car ) and the nitride encapsulation layer (SiN3 Car ) are made of silicon nitride.

4. The substrate (SUB) according to any one of claims 1 to 3, further comprising: - a light-blocking layer (TiN2) Car ) between the separation layer (TiN1 Car ) and the nitride encapsulation layer (SiN3 Car ), the light-blocking layer (TiN2 Car ) and the separation layer (TiN1 Car) being capable of absorbing light of a similar wavelength; and a second nitride layer (SiN2 Car ) between the separation layer (TiN1 Car ) and the light-blocking layer (TiN2 Car ).

5. Substrate (SUB) according to claim 4, wherein the separation layer (TiN1 Car ) and the light-blocking layer (TiN2 Car ) are formed of titanium nitride, and the first nitride layer (SiN1 Car ), the second nitride layer (SiN2 Car ) and the nitride encapsulation layer (SiN3 Car ) are made of silicon nitride.

6. Substrate (SUB) according to any one of claims 1 to 5, wherein the transfer layer (TL) is formed of silicon carbide or silicon.

7. The substrate (SUB) according to any one of claims 1 to 6, wherein the first nitride layer (SiN1 Car ), the encapsulating nitride layer (SiN3 Car) and, where applicable, the second nitride layer (SiN2 Car ), are substantially free of oxygen, and preferably have an oxygen content of less than 1% by mass, and more preferably less than 0.1% by mass.

8. Substrate (SUB) according to any one of claims 1 to 7, wherein a bonding oxide layer (Ox2 Car ) is interposed between the encapsulating nitride layer (SiN3 Car ) and the layer to be transferred (TL).

9. Substrate (SUB) according to any one of claims 1 to 8, wherein the support (Waf Car ) and the separation layer (TiN1 Car ) are respectively substantially transparent and substantially absorbing to light of a given wavelength, so that the layer (TL) to be transferred can be separated from the support (Waf Car ) when the separation layer (TiN1 Car ) is irradiated by light of the given wavelength through the medium (Waf Car) during a light irradiation takeoff operation.

10. Substrate (SUB) according to any one of claims 1 to 9, wherein the encapsulating nitride layer (SiN3 Car ) covers a lateral edge of the separation layer (TiN1 Car ).

11. Process (PR1) for manufacturing a substrate (SUB) capable of releasing a transfer layer by light irradiation from a separating layer, the process comprising, in order: the steps of:- forming (14) a first nitride layer (SiN1 Car ) on a superior surface (Top Car ) and a lower surface (Bot Car ) of a support (Waf Car ), the upper surface being opposite the lower surface; - to form (16) a separation layer (TiN1 Car ) of titanium nitride on the upper surface (Top Car ) of the support (Waf Car ) ;- form (18) an encapsulating nitride layer (SiN3 Car) on the upper surface (Top Car) of the support (Waf Car ), and- form (20, 22, 24, 30, 32) a layer (TL) to be transferred onto the upper surface of the support (Waf Car ) with the separation layer (TiN1 Car ) between the two, in which step (16) of formation of the separation layer (TiN1 Car ) and step (18) of formation of the encapsulating nitride layer (SiN3 Car ) are carried out in such a way that the separation layer (TiN1 Car ) is encapsulated between the first nitride layer (SiN1 Car ) and the encapsulating nitride layer (SiN3 Car ).

12. A method (PR1) according to claim 11, wherein at least one of the steps (14) of forming the first nitride layer (SiN1 Car ) and formation (18) of the encapsulating nitride layer uses a substantially conformal deposition method, preferably a low-pressure chemical vapor deposition.

13. A method (PR1) according to claim 11 or 12, wherein at least step (16) of forming the separation layer (TiN1 Car ) uses plasma-enhanced chemical vapor deposition or physical vapor deposition.

14. A process (PR1) according to any one of claims 11 to 13, wherein step (14) of forming the first nitride layer (SiN1 Car ) completely covers each of the upper surface (Top Car ) and a smaller surface area (Bot Car ) of the support (Waf Car ) with the first nitride layer (SiN1 Car ), the upper surface being opposite the second surface.

15. A method (PR1) according to any one of claims 11 to 14, wherein the step (16) of forming the separation layer (TiN1 Car ) includes the following steps: - glue (30) a donor substrate (Waf Don ) on the upper surface of the support (Waf Car) with the separation layer (TiN1 Car ) interposed between the donor substrate (Waf Don ) and the upper surface of the support (Waf Car ); and- remove (32) part of the donor substrate (Waf Don ).

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