WO2001011667A1 - Method for transferring a thin layer comprising a step of excess fragilization - Google Patents

Method for transferring a thin layer comprising a step of excess fragilization Download PDF

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Publication number
WO2001011667A1
WO2001011667A1 PCT/FR2000/002239 FR0002239W WO0111667A1 WO 2001011667 A1 WO2001011667 A1 WO 2001011667A1 FR 0002239 W FR0002239 W FR 0002239W WO 0111667 A1 WO0111667 A1 WO 0111667A1
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Prior art keywords
thin layer
source substrate
separation
thickness
substrate
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PCT/FR2000/002239
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French (fr)
Inventor
Chrystelle Lagahe
Alain Soubie
Michel Bruel
Bernard Aspar
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Commissariat A L'energie Atomique
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Priority to EP00956612A priority Critical patent/EP1203403A1/en
Priority to JP2001516228A priority patent/JP2003506892A/en
Publication of WO2001011667A1 publication Critical patent/WO2001011667A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/76—Making of isolation regions between components
    • H01L21/762—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers
    • H01L21/7624—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology
    • H01L21/76251—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques
    • H01L21/76254—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/324—Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering

Definitions

  • the present invention relates to a method of transferring a thin layer from a substrate, called source substrate, to a support called target support.
  • the invention finds applications in particular in the fields of microelectronics, micro-mechanics, integrated optics and integrated electronics.
  • the thin layer which is made of a material selected for its physical properties
  • a support in order to form a stack with several layers.
  • the transfer of a layer makes it possible in particular to associate in the same structure parts which a priori exhibit incompatibilities such as a significant difference in coefficients of thermal expansion.
  • the "Smart-cut” process is essentially based on the implantation of hydrogen or another gas in neutral or ionic form in a substrate so as to form there a weakened cleavage zone.
  • the cleavage zone extends, substantially parallel to its surface and is located in the substrate at a depth fixed by the implantation energy.
  • the cleavage zone thus delimits in the substrate a thin surface layer which extends in thickness from the cleavage zone to the surface of the substrate.
  • a second step comprises the adhesion of the source substrate with a target support so that the thin layer is integral with the target support.
  • the fixing of the thin layer on the target support can take place by means of an adhesive and / or by means of a bonding layer. I t may also take place by direct molecular bonding between the substrate surface and the surface o f the target medium.
  • a final step in the process consists in fracturing the substrate according to the cleavage zone in order to separate the thin layer therefrom. This then remains solid with the target support.
  • the fracture (or cleavage) of the substrate is caused by supplying energy in the form of a heat treatment.
  • the implantation conditions define the cleavage zone and condition the separation of the thin layer from the substrate.
  • document (2) which proposes a process derived from that of document (1).
  • Document (2) provides a method for obtaining the separation of its original substrate from a thin film which is self-supporting. For this, it is necessary that the implanted gaseous species are at a sufficient depth and / or that a layer of a material is deposited, after the implantation step, making it possible to stiffen the structure to obtain separation at of the implanted area without having blisters.
  • the document (4) which also describes a process based on the principle established by the document (1), shows that the thermal budget used to cause the fracture of the source substrate depends on the thermal budgets of all the heat treatments imposed on the source substrate from implantation to fracture.
  • thermal budget is meant the couple of heat treatment time / heat treatment temperature.
  • a solution to this problem then consists in modifying the implantation conditions by carrying out an overdose of the implanted species. Such an overdose in fact makes it possible to reduce the thermal budget of the separation fracture (cleavage).
  • a dose of implanted hydrogen ions of 1.10 17 / cm 2 instead of 6.10 16 / cm 2 , allows for a heat treatment duration of a few hours to lower the temperature from 400 ° C to 280 ° C.
  • the solution of overdosing the implantation is not always satisfactory because of the difference in coefficient of thermal expansion that may exist between the substrate and the support.
  • the thermal budget necessary for the separation can be such that it causes the separation of the substrate and the support and / or the breaking of the substrate and / or the support in their volume.
  • Disclosure of the invention aims to provide a method of transferring a thin layer, not presenting the difficulties and limitations of the methods indicated above.
  • One goal is in particular to propose such a process which implements a reduced thermal budget see null to obtain a separation fracture of the thin layer.
  • Another object is to propose a method suitable for the transfer of a thin layer onto a target support, in which the materials of the thin layer and of the target support have different coefficients of thermal expansion.
  • Yet another object is to propose a transfer process in which an excellent surface condition of the source substrate (without blisters) can be preserved so as to allow good adhesion with the target support, with or without the addition of a binder (glue), and by allowing a very weakened cleavage zone.
  • an object of the invention is to propose a transfer method making it possible to obtain, after transfer, a thin layer on the target support, which has a free surface with low roughness.
  • the invention more specifically relates to a process for transferring a thin layer from a source substrate to a target support comprising, in order, the following steps: a) implantation of ions or gaseous species in the source substrate so as to form there a zone, called a cleavage zone, which delimits said thin layer in the source substrate, b) the transfer of the source substrate to the target support and the joining of the thin layer with the target support, c) separation of the thin layer from the source substrate according to the cleavage zone.
  • the process comprises, before step b),
  • the step of forming a film thickness consists in performing step a) of implantation so as to obtain the cleavage zone at said thickness, the film then being formed by the thin layer.
  • the step of forming a film thickness consists in carrying out a step of forming a so-called thickener layer on the thin layer, the thin layer and the layer of thickness then forming the film.
  • the limiting thickness of the film is the thickness making it possible to stiffen the structure in order to obtain the separation of the film at the level of the cleavage zone without the appearance of blisters on the surface. It is this limiting thickness which makes it possible to obtain self-supporting films. This thickness depends in particular on the mechanical properties of the materials, but also on the separation conditions of step c) such as for example the rise in temperature of the heat treatment.
  • the invention also comprises the production, before step b), of all or part of microelectric and / or micromechanical and / or optoelectronic components.
  • the separation of the thin layer from the source substrate, carried out in step c) can take place under the effect of a heat treatment, under the effect of mechanical forces or under the effect of these actions. combined.
  • the thermal budget and / or the mechanical forces used during step c) for the separation fracture can be particularly reduced. This has the advantage of not causing a break in adhesion between the thin film and the target support, even in the event of a difference in the coefficients of thermal expansion of the materials brought into contact.
  • Another advantage of the invention is to eliminate or reduce the mechanical forces exerted on the parts in contact and thus avoid damaging them. This facilitates separation.
  • step of over-embrittlement is not limited by the effects of differential expansion constraints insofar as this step is carried out before the transfer of the source substrate to the target support (step b).
  • the over-embrittlement comprises a heat treatment implemented with a thermal budget greater than or equal to 50%, and preferably greater than 60%, of an overall thermal budget allowing the separation.
  • the overall thermal budget considered here takes into account not only the heat treatments carried out within the strict framework of the process of the invention, but also includes any heat treatments used, for example, for the production of components or for the deposition of materials on the thin layer between steps a) and b).
  • steps c) and the over-embrittlement step may include an exercise of mechanical forces.
  • thermal separation treatment can also be chosen sufficient to cause during step c) a separation of the thin layer, by simple separation of the source substrate and the target support or a total separation only by this thermal treatment.
  • the implantation step a) makes it possible to form cavities located in the cleavage zone in the source substrate.
  • the cavities can be in different forms. They can be spherical and / or flattened with a thickness of only a few inter-atomic distances. Furthermore, the cavities may contain a free gas phase and / or gas atoms from the implanted ions, fixed on the atoms of the material forming the walls of the cavities or contain little or even no gas.
  • This phenomenon also makes it possible to obtain, after the transfer and the separation fracture, a free surface of the thin layer with low roughness.
  • the thickener layer for example made of Si, Si0 2 , Si 3 N 4 or even Sic, covers the thin layer in whole or in part.
  • the thickness of the thickener layer to obtain a film thickness is chosen for example from a range from 3 to 10 ⁇ m for a Si0 2 thickener.
  • a layer used as a thickener layer may be a layer which is also used in whole or in part for producing electronic, optoelectronic, or mechanical components on the surface of the thin layer.
  • the invention also relates to a method of transferring a thin layer from a source substrate comprising the following steps: a) implantation of ions or gaseous species in the source substrate so as to form a zone therein, known as cleavage, which delimits said thin layer in the source substrate, b) separation of the thin layer from the source substrate according to the cleavage zone, in accordance with the invention, the method further comprises, prior to step b):
  • the invention makes it possible to obtain very significant overgreenings, which can range up to 80 to 90% of the complete separation thanks to the presence of a thickener.
  • This thickener is deposited on the surface with the aim of increasing the overgreening.
  • FIG. 1 is a schematic section of a source substrate and illustrates an ion implantation operation.
  • - Figure 2 is a schematic section of the source substrate of Figure 1 and illustrates the formation of a thick layer.
  • - Figure 3 is a schematic section of the source substrate of Figure 2 and illustrates a weakening step.
  • FIG. 4 is a schematic section of a structure formed from the source substrate of Figure 3, transferred to a target support.
  • Figure 5 is a schematic section of the structure of Figure 4 after separation fracture of the source substrate.
  • the following description relates to a transfer of a thin layer of silicon onto a target support of molten silica (incorrectly called quartz).
  • the invention can however be implemented for other solid materials, whether they are crystalline or not. These materials can be dielectric, conductive, semi-insulating or semi-conducting.
  • the target support can be a final or intermediate support, such as a handle, a solid substrate or a multilayer substrate.
  • the process can in particular be used for the transfer of layers of non-semiconductor, ferroelectric, piezoelectric materials such as for example LiNb0 3 or III-V semiconductors such as AsGa, InP on silicon or SiC.
  • non-semiconductor, ferroelectric, piezoelectric materials such as for example LiNb0 3 or III-V semiconductors such as AsGa, InP on silicon or SiC.
  • FIG. 1 shows an initial silicon substrate 10. This undergoes ion implantation hydrogen indicated with arrows 12. This layout corresponds to step a ⁇ ) of the process.
  • the implantation carried out for example with a dose of 6.10 16 / cm 2 and an energy of 70 keV, makes it possible to form microcavities 14 in the substrate 10 at a depth of the order of 7000 A.
  • This depth also corresponds to the thickness of a thin layer 18. This is delimited on the surface of the substrate by an area 16, called a cleavage area, comprising the microcavities 14.
  • the thin surface layer 18 may be subjected to other treatments, known per se, for the formation in this layer of electronic, optical, or mechanical components. These components are not shown in the figure for reasons of clarity. In this case, these stages are taken into account for the overgreening.
  • FIG. 2 which corresponds to the step of using a thickness of the process, shows the deposition of a layer of silicon oxide 20 with a thickness of the order of, or greater than 5 ⁇ m, on the thin layer 18.
  • the silicon oxide layer is for example deposited by a chemical gas deposition process assisted by plasma at a temperature of 300 ° C. Thermal budgets are chosen in such a way so that they avoid the appearance of blisters during the thicknessing stage.
  • the silicon oxide layer 20 acts as a thickener for the thin layer 18. In other words, its function is to prevent deformation of the thin layer under the effect of subsequent heat treatments.
  • FIG. 3 corresponds to the process of over-embrittlement of the process. During this step, the substrate is subjected to treatments aimed at further weakening the cleavage zone 16.
  • a heat treatment is carried out at a temperature of the order of 450 ° C for a period of the order of 12 minutes.
  • This thermal budget is preferably greater than 60% of the thermal budget necessary to obtain separation only by annealing. Such over-embrittlement is possible with a sufficient thickness of film.
  • the layer of thickness 20 which covers the thin layer 18, prevents its deformation and in particular prevents the formation of blisters.
  • the heat treatment can be followed by a step of polishing the free face of the thickener layer 20 just to improve the surface roughness so as to prepare it for molecular bonding.
  • Figure 4 shows the transfer of the source substrate 10 on a target support 30 which, in this case, is a quartz plate.
  • the transfer is carried out so as to bring a flat face of the target support into contact with the free flat face of the thickener layer 20.
  • the transfer can take place by means of a binder or an adhesive.
  • the molecular adhesion forces can be reinforced for example by a heat treatment and / or by surface preparations.
  • the heat treatment is carried out at a relatively low temperature, of the order of 200 ° C. for a period of 20 hours. This heat treatment can contribute to inducing stresses such that the fracture of the substrate can be obtained according to this zone.
  • FIG. 5 illustrates step c) of the method which corresponds to a fracture of the source substrate.
  • the fracture takes place according to the cleavage zone and separates the thin layer 18 from the remaining part of the substrate 10. This last part can then be reused for example for a new transfer of thin layer.
  • the thin layer 18 remains integral with the support
  • the thickener layer can be omitted.
  • the thin layer is then directly in contact with the target support.
  • the fracture of the source substrate can be caused by the exercise of mechanical force and / or by heat treatment.
  • a razor blade In the example shown, a razor blade
  • the invention applies particularly well to the production of a thin layer of silicon on molten silica, the main advantage of which is to have a transparent support with a semiconductor layer which may include components.

Abstract

The invention concerns a method for transferring a thin layer (18) from a source substrate (10) to a target support (30) comprising the following steps: a) implanting ions or gaseous species into the source substrate so as to form therein a zone (16) called cleavage zone, delimiting said thin layer (18) in the source substrate; b) transferring the substrate source onto the target support and making the thin layer integral with the target source; c) separating the thin layer (18) from the source substrate (10) along the cleavage zone. The invention is characterised in that the method comprises, prior to step b): a process for excess fragilization of the cleavage zone (16) produced by a heat treatment and/or by exerting mechanical stresses on the source substrate.

Description

PROCEDE DE TRANSFERT D'UNE COUCHE MINCE COMPORTANT UNE ETAPE DE SURFRAGILISATION METHOD FOR TRANSFERRING A THIN FILM HAVING A SURFRAGILIZATION STEP
Domaine techniqueTechnical area
La présente invention concerne un procédé de transfert d'une couche mince d'un substrat, dit substrat source, vers un support appelé support cible.The present invention relates to a method of transferring a thin layer from a substrate, called source substrate, to a support called target support.
L'invention trouve des applications en particulier dans les domaines de la micro-électronique, de la micro-mécanique, de l'optique intégrée et de l'électronique intégrée.The invention finds applications in particular in the fields of microelectronics, micro-mechanics, integrated optics and integrated electronics.
Elle permet, par exemple de réaliser des structures dans lesquelles la couche mince, qui est en un matériau sélectionné pour ses propriétés physiques, est reportée sur un support afin de former un empilement à plusieurs couches. Ainsi, on peut combiner les avantages des matériaux de la couche mince et du support. Le report d'une couche permet notamment d'associer dans une même structure des parties qui présentent a priori des incompatibilités telles qu'une différence importante de coefficients de dilatation thermique.It allows, for example to produce structures in which the thin layer, which is made of a material selected for its physical properties, is transferred to a support in order to form a stack with several layers. Thus, the advantages of the thin film materials and the support can be combined. The transfer of a layer makes it possible in particular to associate in the same structure parts which a priori exhibit incompatibilities such as a significant difference in coefficients of thermal expansion.
Etat de la technique antérieureState of the art
Le texte qui suit se réfère à un certain nombre de documents dont les références complètes sont précisées à la fin de la description.The following text refers to a certain number of documents, the full references of which are given at the end of the description.
Parmi les procédés généralement mis en oeuvre pour la formation de couches minces, on peut citer en particulier un procédé de clivage, bien connu sous la dénomination "Smart-cut", et illustré par le documentAmong the methods generally used for the formation of thin layers, there may be mentioned in particular a cleavage method, well known under the name "Smart-cut", and illustrated by the document.
U)- Le procédé "Smart-cut" est basé essentiellement sur l'implantation d'hydrogène ou d'un autre gaz sous forme neutre ou ionique dans un substrat de façon à y former une zone de clivage fragilisée. Dans le cas d'un substrat plan, la zone de clivage s'étend, de façon sensiblement parallèle a sa surface et est située dans le substrat à une profondeur fixée par l'énergie d'implantation. La zone de clivage délimite ainsi dans le substrat une couche superficielle mince qui s'étend en épaisseur depuis la zone de clivage jusqu'à la surface du substrat.U) - The "Smart-cut" process is essentially based on the implantation of hydrogen or another gas in neutral or ionic form in a substrate so as to form there a weakened cleavage zone. In the case of a flat substrate, the cleavage zone extends, substantially parallel to its surface and is located in the substrate at a depth fixed by the implantation energy. The cleavage zone thus delimits in the substrate a thin surface layer which extends in thickness from the cleavage zone to the surface of the substrate.
Une deuxième étape comprend la mise en adhérence du substrat source avec un support cible de telle façon que la couche mince soit solidaire du support cible. La fixation de la couche mince sur le support cible peut avoir lieu au moyen d'une colle et/ou par l'intermédiaire d'une couche de liaison. Elle peut avoir lieu également par adhérence moléculaire directe entre la surface du substrat et la surface du support cible.A second step comprises the adhesion of the source substrate with a target support so that the thin layer is integral with the target support. The fixing of the thin layer on the target support can take place by means of an adhesive and / or by means of a bonding layer. I t may also take place by direct molecular bonding between the substrate surface and the surface o f the target medium.
Dans ce dernier cas, il est cependant nécessaire que les faces que l'on souhaite faire adhérer présentent certaines propriétés comme une bonne planéité et une faible rugosité. Une dernière étape du procédé consiste à fracturer le substrat selon la zone de clivage pour en séparer la couche mince. Celle-ci reste alors solidaire du support cible.In the latter case, it is however necessary that the faces which it is desired to adhere have certain properties such as good flatness and low roughness. A final step in the process consists in fracturing the substrate according to the cleavage zone in order to separate the thin layer therefrom. This then remains solid with the target support.
Dans le cas du procédé décrit par le document (1), la fracture (ou clivage) du substrat est provoquée par apport d'énergie sous forme d'un traitement thermique .In the case of the process described in document (1), the fracture (or cleavage) of the substrate is caused by supplying energy in the form of a heat treatment.
Les conditions d'implantation définissent la zone de clivage et conditionnent la séparation de la couche mince d'avec le substrat.The implantation conditions define the cleavage zone and condition the separation of the thin layer from the substrate.
Or, on a observé qu'une trop grande fragilisation de la zone de clivage après l'implantation, bien que favorable pour la séparation, provoque des déformations de la surface de la couche mince. Les déformations se présentent sous la forme de cloques et constituent un obstacle pour la fixation.de la couche mince sur le support cible.However, it has been observed that too much embrittlement of the cleavage zone after implantation, although favorable for separation, causes deformations of the surface of the thin layer. The deformations are in the form of blisters and constitute an obstacle for fixation . of the thin layer on the target support.
Cette trop grande fragilisation, peut être liée à une implantation ionique à forte dose ou à une implantation ionique à plus faible dose associée à un recuit. La trop grande fragilisation peut donc induire l'apparition de cloques en surface d'autant plus facilement que la zone fragilisée est proche de la surface. Dans certaines applications on souhaite obtenir des films minces autoportés, c'est-à-dire qui peuvent être séparée du substrat source sans être préalablement fixés sur un support.This excessive embrittlement can be linked to a high dose ion implantation or to a lower dose ion implantation associated with annealing. Too much embrittlement can therefore induce the appearance of blisters on the surface all the more easily the closer the weakened area is to the surface. In certain applications, it is desired to obtain self-supporting thin films, that is to say films which can be separated from the source substrate without being previously fixed on a support.
Ces films minces peuvent alors être reportés ultérieurement sur différents supports cibles et, en particulier, sur des supports avec lesquels le substrat source ne peut pas être mis en adhérence avant la séparation de la couche mince, par exemple, pour des raisons de compatibilité des coefficients de dilatation thermique. On peut à ce sujet se reporter au document (2) qui propose un procédé dérivé de celui du document ( 1 ) . Le document (2) propose un procédé permettant d'obtenir la séparation de son substrat d'origine, d'un film mince qui est autoporté. Pour cela, il faut que les espèces gazeuses implantées se trouvent à une profondeur suffisante et/ou que l'on dépose, après l'étape d'implantation, une couche d'un matériau permettant de rigidifier la structure pour obtenir la séparation au niveau de la zone implantée sans avoir de cloques.These thin films can then be transferred later on different target supports and, in particular, on supports with which the source substrate cannot be adhered before the separation of the thin layer, for example, for reasons of compatibility of the coefficients thermal expansion. On this subject, we can refer to document (2) which proposes a process derived from that of document (1). Document (2) provides a method for obtaining the separation of its original substrate from a thin film which is self-supporting. For this, it is necessary that the implanted gaseous species are at a sufficient depth and / or that a layer of a material is deposited, after the implantation step, making it possible to stiffen the structure to obtain separation at of the implanted area without having blisters.
L'illustration de la technique de formation d'une couche mince par clivage d'un substrat, peut être complétée par le document ( 3 ) qui suggère de compléter le traitement thermique de fracture (clivage) du substrat par l'exercice de forces mécaniques de flexion, de traction et/ou de cisaillement.The illustration of the technique of forming a thin layer by cleavage of a substrate, can be supplemented by document (3) which suggests completing the thermal treatment of fracture (cleavage) of the substrate by the exercise of mechanical forces. of bending, traction and / or shearing.
Le document (4) qui décrit également un procédé basé sur le principe établi par le document ( 1 ) , montre que le budget thermique mis en oeuvre pour provoquer la fracture du substrat source dépend des budgets thermiques de tous les traitements thermiques imposés au substrat source depuis l'implantation jusqu'à la fracture. On entend par budget thermique le couple durée de traitement thermique/température de traitement thermique.The document (4) which also describes a process based on the principle established by the document (1), shows that the thermal budget used to cause the fracture of the source substrate depends on the thermal budgets of all the heat treatments imposed on the source substrate from implantation to fracture. By thermal budget is meant the couple of heat treatment time / heat treatment temperature.
Dans un certain nombre d'applications il est nécessaire d'assembler une couche mince d'un substrat source avec un support cible qui présente un coefficient de dilatation thermique différent de celui du substrat source.In a number of applications it is necessary to assemble a thin layer of a source substrate with a target support which has a coefficient of thermal expansion different from that of the source substrate.
Dans ces applications, il est généralement délicat de soumettre la structure obtenue après assemblage du substrat source et du support cible, à un traitement thermique avec un budget thermique suffisant pour garantir la séparation de la couche mince d'avec le substrat source.In these applications, it is generally difficult to subject the structure obtained after assembly of the source substrate and the target support, to a heat treatment with a sufficient thermal budget to guarantee the separation of the thin layer from the source substrate.
Une solution à ce problème consiste alors à modifier les conditions d'implantation en effectuant un surdosage des espèces implantées. Un tel surdosage permet en effet de réduire le budget thermique de la fracture de séparation (clivage).A solution to this problem then consists in modifying the implantation conditions by carrying out an overdose of the implanted species. Such an overdose in fact makes it possible to reduce the thermal budget of the separation fracture (cleavage).
A titre d'exemple, lorsque le substrat source est une plaque de silicium, une dose d'ions d'hydrogène implantés, de 1.1017/cm2 au lieu de 6.1016/cm2, permet pour une durée de traitement thermique de quelques heures d'en abaisser la température de 400 °C à 280 °C.For example, when the source substrate is a silicon wafer, a dose of implanted hydrogen ions, of 1.10 17 / cm 2 instead of 6.10 16 / cm 2 , allows for a heat treatment duration of a few hours to lower the temperature from 400 ° C to 280 ° C.
La solution consistant à surdoser l'implantation n'est cependant pas toujours satisfaisante en raison de la différence de coefficient de dilatation thermique pouvant exister entre le substrat et le support. En effet, le budget thermique nécessaire à la séparation peut être tel qu'il provoque le décollement du substrat et du support et/ou la cassure du substrat et/ou du support dans leur volume.However, the solution of overdosing the implantation is not always satisfactory because of the difference in coefficient of thermal expansion that may exist between the substrate and the support. Indeed, the thermal budget necessary for the separation can be such that it causes the separation of the substrate and the support and / or the breaking of the substrate and / or the support in their volume.
Une solution alternative pour éviter un décollement entre la couche mince et le support cible sous l'effet d'une dilatation différentielle, consiste à amincir le substrat source avant l'étape de fracture (clivage) . Cette solution, suggérée par le document (5), présente toutefois l'inconvénient d'une opération supplémentaire d'amincissement et celui d'une consommation de matière importante . La mise en oeuvre de forces mécaniques pour séparer le substrat source de la couche mince, telle qu'évoquée ci-dessus en référence au document (3), permet également de réduire le budget thermique de fracture, notamment dans le cas où les matériaux en contact présentent des coefficients de dilatation différents. L'exercice d'efforts mécaniques sur le substrat source et/ou le support cible n'est toutefois pas toujours possible, notamment lorsque les matériaux mis en oeuvre sont fragiles, ou lorsque la zone de clivage n'est pas assez fragilisée par l'implantation ionique.An alternative solution to avoid detachment between the thin layer and the target support under the effect of differential expansion, consists in thinning the source substrate before the fracture step (cleavage). This solution, suggested by document (5), however has the drawback of an additional thinning operation and that of a significant consumption of material. The use of mechanical forces to separate the source substrate from the thin layer, as mentioned above with reference to document (3), also makes it possible to reduce the thermal fracture budget, especially in the case where the materials in contact have different expansion coefficients. The exercise of mechanical forces on the source substrate and / or the target support is however not always possible, in particular when the materials used are fragile, or when the cleavage zone is not sufficiently weakened by the ion implantation.
Finalement, les techniques de séparation et de transfert de couche mince, décrites ci-dessus, impliquent un certain nombre de contraintes et de compromis. Ces contraintes sont imposées en particulier par le type de matériaux utilisés pour constituer le substrat source, la couche mince et le support cible.Finally, the separation and thin film transfer techniques described above involve a certain number of constraints and compromises. These constraints are imposed in particular by the type of materials used to constitute the source substrate, the thin layer and the target support.
Exposé de 1 ' invention La présente invention a pour but de proposer un procédé de transfert d'une couche mince, ne présentant pas les difficultés et limitations des procédés indiquées ci-dessus.Disclosure of the invention The present invention aims to provide a method of transferring a thin layer, not presenting the difficulties and limitations of the methods indicated above.
Un but est en particulier de proposer un tel procédé qui mette en oeuvre un budget thermique réduit voir nul pour obtenir une fracture de séparation de la couche mince.One goal is in particular to propose such a process which implements a reduced thermal budget see null to obtain a separation fracture of the thin layer.
Un autre but est de proposer un procédé adapté au transfert d'une couche mince sur un support cible, dans lequel les matériaux de la couche mince et du support cible présentent des coefficients de dilatation thermique différents.Another object is to propose a method suitable for the transfer of a thin layer onto a target support, in which the materials of the thin layer and of the target support have different coefficients of thermal expansion.
Encore un autre but est de proposer un procédé de transfert dans lequel un excellent état de surface du substrat source (sans cloques) peut être préservé de façon à autoriser une bonne adhérence avec le support cible, avec ou sans apport de liant (colle), et en permettant d'avoir une zone de clivage très fragilisée.Yet another object is to propose a transfer process in which an excellent surface condition of the source substrate (without blisters) can be preserved so as to allow good adhesion with the target support, with or without the addition of a binder (glue), and by allowing a very weakened cleavage zone.
Enfin, un but de l'invention est de proposer un procédé de transfert permettant d'obtenir, après transfert, une couche mince sur le support cible, qui présente une surface libre avec une faible rugosité.Finally, an object of the invention is to propose a transfer method making it possible to obtain, after transfer, a thin layer on the target support, which has a free surface with low roughness.
Pour atteindre ces buts, l'invention a plus précisément pour objet un procédé de transfert d'une couche mince d'un substrat source vers un support cible comportant, dans l'ordre, les étapes suivantes : a) une implantation d'ions ou d'espèces gazeuses dans le substrat source de façon à y former une zone, dite de clivage, qui délimite ladite couche mince dans le substrat source, b) le report du substrat source sur le support cible et la solidarisation de la couche mince avec le support cible, c) la séparation de la couche mince d'avec le substrat source selon la zone de clivage. Conformément à l'invention, le procédé comporte préalablement à l'étape b),To achieve these goals, the invention more specifically relates to a process for transferring a thin layer from a source substrate to a target support comprising, in order, the following steps: a) implantation of ions or gaseous species in the source substrate so as to form there a zone, called a cleavage zone, which delimits said thin layer in the source substrate, b) the transfer of the source substrate to the target support and the joining of the thin layer with the target support, c) separation of the thin layer from the source substrate according to the cleavage zone. In accordance with the invention, the process comprises, before step b),
- une formation d'une épaisseur de film de matériau entre la zone de clivage et la surface du substrat, telle, que cette épaisseur soit supérieure, égale ou voisine d'une épaisseur limite pour laquelle le film est autoporté, eta formation of a thickness of film of material between the cleavage zone and the surface of the substrate, such that this thickness is greater than, equal to or close to a limit thickness for which the film is self-supporting, and
- une surfragilisation de la zone de clivage provoquée par un traitement thermique et/ou par l'exercice d'efforts mécaniques sur le substrat source.- over-embrittlement of the cleavage zone caused by a heat treatment and / or by the exercise of mechanical forces on the source substrate.
Selon un premier mode de réalisation de l'invention, l'étape de formation d'une épaisseur de film consiste à réaliser l'étape a) d'implantation de façon à obtenir la zone de clivage à ladite épaisseur, le film étant alors constitué par la couche mince.According to a first embodiment of the invention, the step of forming a film thickness consists in performing step a) of implantation so as to obtain the cleavage zone at said thickness, the film then being formed by the thin layer.
Selon un deuxième mode de réalisation de l'invention, l'étape de formation d'une épaisseur de film consiste à réaliser une étape de formation d'une couche dite d'épaississeur sur la couche mince, la couche mince et la couche d'épaisseur formant alors le film.According to a second embodiment of the invention, the step of forming a film thickness consists in carrying out a step of forming a so-called thickener layer on the thin layer, the thin layer and the layer of thickness then forming the film.
L'épaisseur limite du film est l'épaisseur permettant de rigidifier la structure pour obtenir la séparation du film au niveau de la zone de clivage sans apparition en surface de cloques. C'est cette épaisseur limite qui permet d'obtenir des films autoportés. Cette épaisseur dépend en particulier des propriétés mécaniques des matériaux, mais aussi des conditions de séparation de l'étape c) telle que par exemple la montée en température du traitement thermique. Selon un mode avantageux, l'invention comporte également la réalisation, avant l'étape b), de tout ou partie de composants micro-électriques et/ou micromécaniques et/ou optoélectroniques . La séparation de la couche mince d'avec le substrat source, opérée à l'étape c), peut avoir lieu sous l'effet d'un traitement thermique, sous l'effet d'efforts mécaniques ou sous l'effet de ces actions combinées . Or, grâce à l'étape de surfragilisation, le budget thermique et/ou les efforts mécaniques mis -en oeuvre lors de l'étape c) pour la fracture de séparation peuvent être particulièrement réduits. Ceci a pour avantage de ne pas provoquer de rupture d'adhérence entre le film mince et le support cible, même en cas d'une différence des coefficients de dilatation thermique des matériaux mis en contact.The limiting thickness of the film is the thickness making it possible to stiffen the structure in order to obtain the separation of the film at the level of the cleavage zone without the appearance of blisters on the surface. It is this limiting thickness which makes it possible to obtain self-supporting films. This thickness depends in particular on the mechanical properties of the materials, but also on the separation conditions of step c) such as for example the rise in temperature of the heat treatment. According to an advantageous embodiment, the invention also comprises the production, before step b), of all or part of microelectric and / or micromechanical and / or optoelectronic components. The separation of the thin layer from the source substrate, carried out in step c), can take place under the effect of a heat treatment, under the effect of mechanical forces or under the effect of these actions. combined. However, thanks to the over-embrittlement step, the thermal budget and / or the mechanical forces used during step c) for the separation fracture can be particularly reduced. This has the advantage of not causing a break in adhesion between the thin film and the target support, even in the event of a difference in the coefficients of thermal expansion of the materials brought into contact.
Un autre avantage de 1 ' invention est de supprimer ou réduire les efforts mécaniques exercés sur les parties en contact et éviter ainsi de les détériorer. On facilite ainsi la séparation.Another advantage of the invention is to eliminate or reduce the mechanical forces exerted on the parts in contact and thus avoid damaging them. This facilitates separation.
Il convient de noter que l'étape de surfragilisation n'est pas limitée par des effets de contraintes de dilatation différentielle dans la mesure où cette étape est effectuée avant le report du substrat source sur le support cible (étape b).It should be noted that the step of over-embrittlement is not limited by the effects of differential expansion constraints insofar as this step is carried out before the transfer of the source substrate to the target support (step b).
Selon un aspect avantageux, la surfragilisation comporte un traitement thermique mis en oeuvre avec un budget thermique supérieur ou égal à 50%, et de préférence supérieur à 60%, d'un budget thermique global permettant la séparation. Le budget thermique global considéré ici prend en compte non seulement les traitements thermiques opérés dans le strict cadre du procédé de l'invention, mais comprend également d'éventuels traitements thermiques mis en oeuvre, par exemple, pour la réalisation de composants ou pour le dépôt de matériaux sur la couche mince entre les étapes a) et b) .According to an advantageous aspect, the over-embrittlement comprises a heat treatment implemented with a thermal budget greater than or equal to 50%, and preferably greater than 60%, of an overall thermal budget allowing the separation. The overall thermal budget considered here takes into account not only the heat treatments carried out within the strict framework of the process of the invention, but also includes any heat treatments used, for example, for the production of components or for the deposition of materials on the thin layer between steps a) and b).
Comme évoqué précédemment, les étapes c) et l'étape de surfragilisation peuvent comporter un exercice d'efforts mécaniques.As mentioned above, steps c) and the over-embrittlement step may include an exercise of mechanical forces.
Ces efforts mécaniques comprennent, par exemple, l'application de forces sous la forme d'une pression mécanique et/ou d'une tension mécanique et/ou des forces sous la forme d'une pression de gaz. Le traitement thermique de séparation peut aussi être choisi suffisant pour provoquer lors de l'étape c) une séparation de la couche mince, par simple écartement du substrat source et du support cible ou une séparation totale uniquement par ce traitement thermique.These mechanical forces include, for example, the application of forces in the form of mechanical pressure and / or mechanical tension and / or forces in the form of gas pressure. The thermal separation treatment can also be chosen sufficient to cause during step c) a separation of the thin layer, by simple separation of the source substrate and the target support or a total separation only by this thermal treatment.
L'étape d'implantation a) permet de former dans le substrat source des cavités situées dans la zone de clivage .The implantation step a) makes it possible to form cavities located in the cleavage zone in the source substrate.
Les cavités (ou micro-cavités ou platelets ou microbulles) peuvent se présenter sous différentes formes. Elles peuvent être sphériques et/ou aplaties avec une épaisseur de seulement quelques distances inter-atomiques . Par ailleurs, les cavités peuvent contenir une phase gazeuse libre et/ou des atomes de gaz issus des ions implantés, fixés sur les atomes du matériau formant les parois des cavités ou ne contenir que peu de gaz ou même pas de gaz .The cavities (or micro-cavities or platelets or microbubbles) can be in different forms. They can be spherical and / or flattened with a thickness of only a few inter-atomic distances. Furthermore, the cavities may contain a free gas phase and / or gas atoms from the implanted ions, fixed on the atoms of the material forming the walls of the cavities or contain little or even no gas.
Les traitements thermiques subis par le support source, et en particulier un traitement thermique de surfragilisation du procédé, conduisent à la coalescence de tout ou partie des cavités. La coalescence provoque ainsi la surfragilisation du substrat dans la zone de clivage.The heat treatments undergone by the source support, and in particular a heat treatment for over-weakening the process, lead to the coalescence of all or part of the cavities. Coalescence thus causes over-embrittlement of the substrate in the cleavage zone.
Ce phénomène permet en outre d'obtenir, après le report et la fracture de séparation, une surface libre de la couche mince avec une faible rugosité.This phenomenon also makes it possible to obtain, after the transfer and the separation fracture, a free surface of the thin layer with low roughness.
La couche d'épaississeur, par exemple en Si, Si02, Si3N4 ou encore Sic, recouvre la couche mince en tout ou partie. L'épaisseur de la couche d'épaississeur pour obtenir une épaisseur de film est choisie par exemple dans une gamme allant de 3 à 10 μm pour un épaississeur Si02.The thickener layer, for example made of Si, Si0 2 , Si 3 N 4 or even Sic, covers the thin layer in whole or in part. The thickness of the thickener layer to obtain a film thickness is chosen for example from a range from 3 to 10 μm for a Si0 2 thickener.
Il convient de préciser qu'une couche utilisée comme couche d'épaississeur peut être une couche qui sert également en tout ou partie à la réalisation de composants électroniques, optoélectroniques, ou mécaniques à la surface de la couche mince.It should be specified that a layer used as a thickener layer may be a layer which is also used in whole or in part for producing electronic, optoelectronic, or mechanical components on the surface of the thin layer.
L'invention concerne également un procédé de transfert d'une couche mince d'un substrat source comportant les étapes suivantes : a) une implantation d'ions ou d'espèces gazeuses dans le substrat source de façon à y former une zone, dite de clivage, qui délimite ladite couche mince dans le substrat source, b) la séparation de la couche mince d'avec le substrat source selon la zone de clivage, conformément à l'invention, le procédé comporte en outre, préalablement à l'étape b) :The invention also relates to a method of transferring a thin layer from a source substrate comprising the following steps: a) implantation of ions or gaseous species in the source substrate so as to form a zone therein, known as cleavage, which delimits said thin layer in the source substrate, b) separation of the thin layer from the source substrate according to the cleavage zone, in accordance with the invention, the method further comprises, prior to step b):
- une formation d'une épaisseur de film de matériau entre la zone de clivage et la surface du substrat telle que cette épaisseur soit supérieure, égale ou voisine d'une épaisseur limite pour que le film soit autoporté, eta formation of a thickness of material film between the cleavage zone and the surface of the substrate such that this thickness is greater than, equal to or close to a limit thickness so that the film is self-supporting, and
- une surfragilisation de la zone de clivage provoquée par un traitement thermique et/ou par l'exercice d'efforts mécaniques sur le substrat source.- over-embrittlement of the cleavage zone caused by a heat treatment and / or by the exercise of mechanical forces on the source substrate.
L'invention permet d'obtenir des surfragilisations très importantes, pouvant aller jusqu'à 80 à 90% de la séparation complète grâce à la présence d'un épaississeur. Cet épaississeur est déposé en surface avec pour objectif d'augmenter la surfragilisation.The invention makes it possible to obtain very significant overgreenings, which can range up to 80 to 90% of the complete separation thanks to the presence of a thickener. This thickener is deposited on the surface with the aim of increasing the overgreening.
D'autres caractéristiques et avantages de l'invention ressortiront mieux de la description qui va suivre, en référence aux figures des dessins annexés. Cette description est donnée à titre purement illustratif et non limitatif.Other characteristics and advantages of the invention will emerge more clearly from the description which follows, with reference to the figures of the appended drawings. This description is given purely by way of non-limiting illustration.
Brève description des figuresBrief description of the figures
- La figure 1 est une coupe schématique d'un substrat source et illustre une opération d'implantation d'ions.- Figure 1 is a schematic section of a source substrate and illustrates an ion implantation operation.
- La figure 2 est une coupe schématique du substrat source de la figure 1 et illustre la formation d'une couche d'épaisseur. - La figure 3 est une coupe schématique du substrat source de la figure 2 et illustre une étape de fragilisation.- Figure 2 is a schematic section of the source substrate of Figure 1 and illustrates the formation of a thick layer. - Figure 3 is a schematic section of the source substrate of Figure 2 and illustrates a weakening step.
- La figure 4 est une coupe schématique d'une structure formée du substrat source de la figure 3, reporté sur un support cible.- Figure 4 is a schematic section of a structure formed from the source substrate of Figure 3, transferred to a target support.
- La figure 5 est une coupe schématique de la structure de la figure 4 après fracture de séparation du substrat source.- Figure 5 is a schematic section of the structure of Figure 4 after separation fracture of the source substrate.
Description détaillée d'un mode de mise en oeuyre de 1 ' inventionDetailed description of an embodiment of the invention
La description qui suit se rapporte à un transfert d'une couche mince de silicium sur un support cible de silice fondue (appelée abusivement quartz).The following description relates to a transfer of a thin layer of silicon onto a target support of molten silica (incorrectly called quartz).
L ' invention peut cependant être mise en oeuvre pour d'autres matériaux solides, qu'ils soient cristallins ou non. Ces matériaux peuvent être diélectriques, conducteurs, semi-isolants ou semi- conducteurs.The invention can however be implemented for other solid materials, whether they are crystalline or not. These materials can be dielectric, conductive, semi-insulating or semi-conducting.
De même, le support cible peut être un support final ou intermédiaire, tel qu'une poignée, un substrat massif ou un substrat multicouche.Likewise, the target support can be a final or intermediate support, such as a handle, a solid substrate or a multilayer substrate.
Le procédé peut en particulier être mis à profit pour le report de couches de matériaux non semiconducteurs, ferroélectriques, piézo-électriques comme par exemple LiNb03 ou de semi-conducteurs III-V tel que AsGa, InP sur du silicium ou du SiC.The process can in particular be used for the transfer of layers of non-semiconductor, ferroelectric, piezoelectric materials such as for example LiNb0 3 or III-V semiconductors such as AsGa, InP on silicon or SiC.
La figure 1 montre un substrat initial 10 en silicium. Celui-ci subit une implantation d'ions hydrogène indiquée avec des flèches 12. Cette implantation correspond à l'étape aλ ) du procédé.FIG. 1 shows an initial silicon substrate 10. This undergoes ion implantation hydrogen indicated with arrows 12. This layout corresponds to step a λ ) of the process.
L'implantation, effectuée par exemple avec une dose de 6.1016/cm2 et une énergie de 70 keV, permet de former des microcavités 14 dans le substrat 10 à une profondeur de l'ordre de 7000 A.The implantation, carried out for example with a dose of 6.10 16 / cm 2 and an energy of 70 keV, makes it possible to form microcavities 14 in the substrate 10 at a depth of the order of 7000 A.
Cette profondeur correspond également à l'épaisseur d'une couche mince 18. Celle-ci est délimitée à la surface du substrat par une zone 16, dite de clivage, comprenant les microcavités 14.This depth also corresponds to the thickness of a thin layer 18. This is delimited on the surface of the substrate by an area 16, called a cleavage area, comprising the microcavities 14.
Antérieurement ou de préférence postérieurement à cette implantation, la couche mince superficielle 18 peut être soumise à d'autres traitements, connus en soi, pour la formation dans cette couche de composants électroniques, optiques, ou mécaniques. Ces composants ne sont pas représentés sur la figure pour des raisons de clarté. Dans ce cas, on tient compte de ces étapes pour la surfragilisation.Prior to or preferably after this implantation, the thin surface layer 18 may be subjected to other treatments, known per se, for the formation in this layer of electronic, optical, or mechanical components. These components are not shown in the figure for reasons of clarity. In this case, these stages are taken into account for the overgreening.
De même, pour une meilleure lisibilité des figures, les différentes couches ou caractéristiques représentées, ne le sont pas selon une échelle uniforme. En particulier, les couches très minces sont représentées avec une épaisseur exagérée.Similarly, for better readability of the figures, the different layers or characteristics represented are not shown on a uniform scale. In particular, very thin layers are shown with an exaggerated thickness.
La figure 2 qui correspond à l'étape d'utilisation d'un épaisseur du procédé, montre le dépôt d'une couche d'oxyde de silicium 20 d'une épaisseur de l'ordre de, ou supérieure à 5 μm, sur la couche mince 18. La couche d'oxyde de silicium est par exemple déposée par un procédé de dépôt chimique en phase gazeuse assisté par plasma à une température de 300 °C. Les budgets thermiques sont choisis de telle façon qu'ils évitent l'apparition de cloques pendant l'étape de réalisation de l'épaisseur.FIG. 2 which corresponds to the step of using a thickness of the process, shows the deposition of a layer of silicon oxide 20 with a thickness of the order of, or greater than 5 μm, on the thin layer 18. The silicon oxide layer is for example deposited by a chemical gas deposition process assisted by plasma at a temperature of 300 ° C. Thermal budgets are chosen in such a way so that they avoid the appearance of blisters during the thicknessing stage.
La couche d'oxyde de silicium 20 a un rôle d'épaississeur de la couche mince 18. En d'autres termes, elle a pour fonction de prévenir une déformation de la couche mince sous l'effet de traitements thermiques ultérieurs.The silicon oxide layer 20 acts as a thickener for the thin layer 18. In other words, its function is to prevent deformation of the thin layer under the effect of subsequent heat treatments.
La figure 3 correspond à l'étape de surfragilisation du procédé. Lors de cette étape, le substrat subit des traitements visant à fragiliser davantage encore la zone de clivage 16.FIG. 3 corresponds to the process of over-embrittlement of the process. During this step, the substrate is subjected to treatments aimed at further weakening the cleavage zone 16.
Dans l'exemple illustré, on procède à un traitement thermique effectué à une température de l'ordre de 450 °C pendant une durée de l'ordre de 12 minutes.In the example illustrated, a heat treatment is carried out at a temperature of the order of 450 ° C for a period of the order of 12 minutes.
Ce budget thermique est de préférence supérieur à 60% du budget thermique nécessaire pour obtenir une séparation uniquement par recuit. Une telle surfragilisation est possible avec une épaisseur suffisante de film.This thermal budget is preferably greater than 60% of the thermal budget necessary to obtain separation only by annealing. Such over-embrittlement is possible with a sufficient thickness of film.
On observe que le traitement thermique provoque une coalescence partielle des microcavités 14 de la zone de clivage 16.It is observed that the heat treatment causes a partial coalescence of the microcavities 14 of the cleavage zone 16.
Lors de cette opération, la couche de d'épaisseur 20 qui recouvre la couche mince 18, prévient sa déformation et en particulier prévient la formation de cloques.During this operation, the layer of thickness 20 which covers the thin layer 18, prevents its deformation and in particular prevents the formation of blisters.
En l'absence de cette couche, des cloques seraient susceptibles d'apparaître avec un traitement thermique à 450 °C après une durée de l'ordre de 2 minutes ce qui correspond uniquement à un traitement thermique de 10% du traitement thermique nécessaire à la séparation.In the absence of this layer, blisters would be likely to appear with a heat treatment at 450 ° C. after a period of the order of 2 minutes which corresponds only to a treatment 10% of the heat treatment required for separation.
Le traitement thermique peut être suivi par une étape de polissage de la face libre de la couche d'épaississeur 20 juste pour améliorer la rugosité de surface de façon à la préparer pour un collage moléculaire.The heat treatment can be followed by a step of polishing the free face of the thickener layer 20 just to improve the surface roughness so as to prepare it for molecular bonding.
La figure 4 montre le report du substrat source 10 sur un support cible 30 qui, en l'occurrence, est une plaque de quartz.Figure 4 shows the transfer of the source substrate 10 on a target support 30 which, in this case, is a quartz plate.
Le report est effectué de façon à mettre "en contact une face plane du support cible avec la face plane libre de la couche d'épaississeur 20.The transfer is carried out so as to bring a flat face of the target support into contact with the free flat face of the thickener layer 20.
Des forces d'adhérence moléculaire s ' exerçant au niveau des faces mises en contact assurent la solidarisation (fixation) entre le substrat source et le support cible.Molecular adhesion forces exerted at the level of the surfaces brought into contact ensure the joining (fixing) between the source substrate and the target support.
Lorsqu'une telle adhérence moléculaire n'est pas possible pour des raisons de nature des matériaux ou de qualité des surfaces, le report peut avoir lieu par l'intermédiaire d'un liant ou d'une colle.When such molecular adhesion is not possible for reasons of the nature of the materials or the quality of the surfaces, the transfer can take place by means of a binder or an adhesive.
Les forces d'adhérence moléculaire peuvent être renforcées par exemple par un traitement thermique et/ou par des préparations de surface. Dans l'exemple illustré, et en raison des fortes différences de coefficients de dilatation thermique entre le silicium et le quartz, le traitement thermique est effectué à une température relativement basse, de l'ordre de 200 °C pendant une durée de 20 heures. Ce traitement thermique peut contribuer à induire des contraintes telles que la fracture du substrat peut être obtenue selon cette zone.The molecular adhesion forces can be reinforced for example by a heat treatment and / or by surface preparations. In the example illustrated, and due to the large differences in thermal expansion coefficients between silicon and quartz, the heat treatment is carried out at a relatively low temperature, of the order of 200 ° C. for a period of 20 hours. This heat treatment can contribute to inducing stresses such that the fracture of the substrate can be obtained according to this zone.
La figure 5 illustre l'étape c) du procédé qui correspond à une fracture du substrat source. La fracture a lieu selon la zone de clivage et sépare la couche mince 18 de la partie restante du substrat 10. Cette dernière partie peut alors être réutilisée par exemple pour un nouveau transfert de couche mince. La couche mince 18 reste solidaire du supportFIG. 5 illustrates step c) of the method which corresponds to a fracture of the source substrate. The fracture takes place according to the cleavage zone and separates the thin layer 18 from the remaining part of the substrate 10. This last part can then be reused for example for a new transfer of thin layer. The thin layer 18 remains integral with the support
30 par l'intermédiaire de la couche d'épaississeur 20.30 via the thickener layer 20.
Dans un autre exemple, non représenté, où l'épaisseur de la couche mince est assez importante pour éviter des déformations, la couche d'épaississeur peut être omise. La couche mince est alors directement en contact avec le support cible.In another example, not shown, where the thickness of the thin layer is large enough to avoid deformation, the thickener layer can be omitted. The thin layer is then directly in contact with the target support.
A titre d'exemple, on peut citer l'utilisation d'un substrat en SiC, qui est implanté à environBy way of example, mention may be made of the use of an SiC substrate, which is implanted at approximately
200 KeV de façon à obtenir un film sans épaississeur, d'environ 1,5 μm. Dans cet exemple, la surfragilisation peut être obtenue sans épaississeur.200 KeV so as to obtain a film without thickener, of approximately 1.5 μm. In this example, over-embrittlement can be obtained without a thickener.
La fracture du substrat source peut être provoquée par l'exercice d'une force mécanique et/ou par un traitement thermique. Dans l'exemple illustré, une lame de rasoirThe fracture of the source substrate can be caused by the exercise of mechanical force and / or by heat treatment. In the example shown, a razor blade
(non représentée) peut être insérée à la main au niveau de la zone fragilisée.(not shown) can be inserted by hand at the weakened area.
L'invention s'applique particulièrement bien à la réalisation d'une couche mince de silicium sur de la silice fondue dont l'intérêt principal est d'avoir un support transparent avec une couche de semi-conducteur pouvant comporter des composants.The invention applies particularly well to the production of a thin layer of silicon on molten silica, the main advantage of which is to have a transparent support with a semiconductor layer which may include components.
DOCUMENTS CITESCITED DOCUMENTS
(1) FR-A-2 681 472 (US-A-5 374 564)(1) FR-A-2 681 472 (US-A-5 374 564)
(2) FR-A2 738 671 (US-A-5 714 395)(2) FR-A2 738 671 (US-A-5 714 395)
(3) FR-A-2 748 851(3) FR-A-2 748 851
(4) FR-A-2 767 416(4) FR-A-2 767 416
(5) FR-A-2 755 537 (5) FR-A-2 755 537

Claims

REVENDICATIONS
1. Procédé de transfert d'une couche mince (18) d'un substrat source (10) vers un support cible (30) comportant les étapes suivantes : a) une implantation d'ions ou d'espèces gazeuses dans le substrat source de façon à y former une zone1. Method for transferring a thin layer (18) from a source substrate (10) to a target support (30) comprising the following steps: a) implantation of ions or gaseous species in the source substrate of so as to form an area
(16), dite de clivage, qui délimite ladite couche mince (18) dans le substrat source, b) le report du substrat source sur le support cible et la solidarisation de la couche mince avec le support cible, c) la séparation de la couche mince (18) d'avec le substrat source (10) selon la zone de clivage, caractérisé en ce qu'il comporte préalablement à l'étape b) :(16), called cleavage, which delimits said thin layer (18) in the source substrate, b) the transfer of the source substrate to the target support and the solidification of the thin layer with the target support, c) the separation of the thin layer (18) with the source substrate (10) according to the cleavage zone, characterized in that it comprises, prior to step b):
- la formation d'une épaisseur de film de matériau entre la zone de clivage et la surface du substrat telle que cette épaisseur soit supérieure, égale ou voisine d'une épaisseur limite pour que le film soit autoporté, etthe formation of a thickness of film of material between the cleavage zone and the surface of the substrate such that this thickness is greater than, equal to or close to a limit thickness so that the film is self-supporting, and
- une surfragilisation de la zone de clivage (16) provoquée par un traitement thermique et/ou par l'exercice d'efforts mécaniques sur le substrat source. - an over-embrittlement of the cleavage zone (16) caused by a heat treatment and / or by the exercise of mechanical forces on the source substrate.
2. Procédé selon la revendication 1, dans lequel la séparation de la couche mince (18) d'avec le substrat source (10) est provoquée par un traitement thermique et/ou par l'exercice de forces mécaniques.2. Method according to claim 1, in which the separation of the thin layer (18) from the source substrate (10) is caused by a heat treatment and / or by the exercise of mechanical forces.
3. Procédé selon la revendication 1 ou 2 , dans lequel la surfragilisation comporte un traitement thermique mis en oeuvre avec un budget thermique permettant la séparation.3. Method according to claim 1 or 2, wherein the overgreening includes a treatment thermal implemented with a thermal budget allowing separation.
4. Procédé selon la revendication 2, dans lequel le traitement thermique de séparation est choisi suffisant pour provoquer, lors de l'étape c), une séparation de la couche mince (18), par simple écartement du substrat source et du support cible ou une séparation totale uniquement par ce traitement thermique. 4. Method according to claim 2, in which the thermal separation treatment is chosen to be sufficient to cause, during step c), a separation of the thin layer (18), by simple separation of the source substrate and the target support or total separation only by this heat treatment.
5. Procédé selon la revendication 1, dans lequel l'étape c) et l'étape de surfragilisation comportent l'exercice de forces sous la forme d'une pression mécanique et/ou une tension mécanique et/ou des forces sous la forme d'une pression de gaz. 5. Method according to claim 1, in which step c) and the step of over-embrittlement comprise the exercise of forces in the form of mechanical pressure and / or mechanical tension and / or forces in the form of 'gas pressure.
6. Procédé de transfert d'une couche mince (18) d'un substrat source (10) comportant les étapes suivantes : a) une implantation d'ions ou d'espèces gazeuses dans le substrat source de façon à y former une zone (16)^ dite de clivage, qui délimite ladite couche mince (18) dans le substrat source, b) la séparation de la couche mince (18) d'avec le substrat source (10) selon la zone de clivage, caractérisé en ce qu ' il comporte préalablement à l'étape b) :6. Method for transferring a thin layer (18) from a source substrate (10) comprising the following steps: a) implantation of ions or gaseous species in the source substrate so as to form a zone there ( 16) ^ called cleavage, which delimits said thin layer (18) in the source substrate, b) the separation of the thin layer (18) from the source substrate (10) according to the cleavage zone, characterized in that '' it includes before step b):
- une formation d'une épaisseur de film de matériau entre la zone de clivage et la surface du substrat telle que cette épaisseur soit supérieure, égale ou voisine d'une épaisseur limite pour que le film soit autoporté, et - une surfragilisation de la zone de clivage (16) provoquée par un traitement thermique et/ou par l'exercice d'efforts mécaniques sur le substrat source. a formation of a thickness of material film between the cleavage zone and the surface of the substrate such that this thickness is greater than, equal to or close to a limit thickness so that the film is self-supporting, and - an over-embrittlement of the cleavage zone (16) caused by a heat treatment and / or by the exercise of mechanical forces on the source substrate.
7. Procédé selon la revendication 1, caractérisé en ce que l'étape de formation d'une épaisseur de film consiste à réaliser l'étape a) d'implantation de façon à obtenir la zone de clivage à ladite épaisseur, le film étant alors constitué par la couche mince.7. Method according to claim 1, characterized in that the step of forming a film thickness consists in performing step a) of implantation so as to obtain the cleavage zone at said thickness, the film then being formed by the thin layer.
8. Procédé selon la revendication 1, dans lequel l'étape de formation d'une épaisseur de film comprend la réalisation d'une couche dite d'épaississeur (20) sur la couche mince, la couche mince et la couche d'épaississeur formant alors le film.8. The method of claim 1, wherein the step of forming a film thickness comprises producing a so-called thickener layer (20) on the thin layer, the thin layer and the thickener layer forming then the movie.
9. Procédé selon la revendication 1, comprenant en outre la réalisation, avant l'étape b), de tout ou partie de composants micro-électroniques et/ou micro- mécaniques et/ou opto-électroniques . 9. The method of claim 1, further comprising the production, before step b), of all or part of micro-electronic and / or micro-mechanical and / or opto-electronic components.
PCT/FR2000/002239 1999-08-04 2000-08-03 Method for transferring a thin layer comprising a step of excess fragilization WO2001011667A1 (en)

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JP2001516228A JP2003506892A (en) 1999-08-04 2000-08-03 Method for transferring thin layers with excessive weakening steps

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FR9910121A FR2797347B1 (en) 1999-08-04 1999-08-04 METHOD FOR TRANSFERRING A THIN FILM HAVING A SURFRAGILILIZATION STEP

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WO2008132895A1 (en) * 2007-04-20 2008-11-06 Semiconductor Energy Laboratory Co., Ltd. Method for manufacturing soi substrate and semiconductor device
US8399329B2 (en) 2007-04-20 2013-03-19 Semiconductor Energy Laboratory Co., Ltd. Method for manufacturing SOI substrate and semiconductor device
US8629031B2 (en) 2007-04-20 2014-01-14 Semiconductor Energy Laboratory Co., Ltd. Method for manufacturing SOI substrate and semiconductor device
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US8399337B2 (en) 2007-09-14 2013-03-19 Semiconductor Energy Laboratory Co., Ltd. Method for manufacturing SOI substrate and method for manufacturing semiconductor device
US8211780B2 (en) 2007-12-03 2012-07-03 Semiconductor Energy Laboratory Co., Ltd. Method for manufacturing SOI substrate
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