Classifications

• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
  • C30B25/02—Epitaxial-layer growth
  • C30B25/18—Epitaxial-layer growth characterised by the substrate
  • C30B25/186—Epitaxial-layer growth characterised by the substrate being specially pre-treated by, e.g. chemical or physical means
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
  • C30B23/02—Epitaxial-layer growth
  • C30B23/025—Epitaxial-layer growth characterised by the substrate
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/02—Elements
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
  • C30B29/66—Crystals of complex geometrical shape, e.g. tubes, cylinders
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
  • C30B33/06—Joining of crystals
• • 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
  • H01L21/02002—Preparing wafers
• • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/185—Joining of semiconductor bodies for junction formation
• • 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
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
  • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support

Definitions

• the present invention relates to the growth of a two-dimensional film of a Group IV material of the periodic table of elements having a hexagonal crystalline structure, especially graphene, and a structure comprising such a film.
• Graphene films have a growing interest in different technologies, including electronics, optoelectronics, energy, sensors, biotechnology, composite materials.
• a graphene film is composed of carbon atoms arranged in the form of a two-dimensional hexagonal crystalline structure.
• the mobility of the charge carriers we can note the mobility of the charge carriers, the thermal conductivity in the plane of the film, the optical transparency, good mechanical properties such as strong cohesion or tensile strength, flexibility, or even biocompatibility.
• a first technique uses as support substrate a metal foil ("foil” in the English terminology), in particular copper or nickel, and implements a chemical vapor deposition process (CVD), which stands for Anglo-Saxon. "Chemical Vapor Deposition”) for growing a graphene layer on said support substrate.
• CVD chemical vapor deposition process
• the graphene film thus formed can then be transferred to another medium.
• CTE coefficients of Thermal expansion
• a second disadvantage of the aforementioned technique is that, in order to perfectly and reproducibly control the number of deposited atomic layers of graphene (in particular by avoiding forming areas where an additional layer begins to form), it must be possible to guarantee that the only source of carbon atoms comes from the deposition atmosphere and not from the growth substrate itself.
• the metal sheets tend to absorb the carbon atoms, moreover voluntarily strongly present in the deposition atmosphere, and to release them unintentionally during growth or cooling.
• copper it is considered that this absorption is localized, essentially through the grain boundaries and other defects present in copper sheets, which are polycrystalline.
• nickel it is considered that it tends to temporarily absorb carbon throughout its thickness, or at least several microns from the surface exposed to the carbon atmosphere.
• the limiting solubility of carbon in nickel decreases with temperature, leading to a release of carbon during cooling following growth of the graphene film.
• the copper sheet is well textured and / or oriented (for example by having only oriented grains (1 1 1), because the arrangement different grains (in the manner of a mosaic) can significantly affect the properties of the graphene film.
• a second technique therefore aims to replace the aforementioned metal sheet with a composite substrate formed of a layer of copper deposited on a silicon or sapphire substrate [Miller 2012] [Miller 2013] [Ismach 2010] [Rahimi 2014] [Tao 2012 ].
• the deposition of the copper layer is optimized to promote the orientation (1 1 1) along the axis normal to the substrate, said layer remains textured (polycrystalline) with the presence of orientation variants in the plan ("twins" according to the English terminology).
• the annealing of a copper layer at high temperature makes it possible to grow certain grains but their dimension remains well below one millimeter.
• the graphene films deposited on these composite substrates are of comparable quality to those obtained on copper foils.
• this third technique does not solve the problem of the difference in coefficient of thermal expansion. Moreover, the use of copper monocrystals, which are very expensive and too small, does not lend itself to industrial application. Finally, this technique does not solve the problem of the volume absorption by nickel.
• Wrinkles ("wrinkles" according to the English terminology) of the graphene film are therefore generally observed.
• the metal layer obtained by deposit is polycrystalline.
• the roughness of the deposited films is generally high, which may be greater than ten nanometers.
• the thickness control for deposited films is therefore delicate for low thicknesses, that is to say less than 10 nm.
• An object of the invention is to overcome the aforementioned drawbacks and to design a method for manufacturing a two-dimensional film of a Group IV material having a hexagonal crystalline structure, in particular graphene, which makes it possible to precisely control the growth of one or more atomic layers and which provides a film of better quality than currently available films.
• the invention provides a method for producing a two-dimensional film of a Group IV material having a hexagonal crystalline structure, said method comprising:
• the metal film comprises at least one of the following metals: nickel, copper, platinum, cobalt, chromium, iron, zinc, aluminum, iridium, ruthenium, silver.
• the metal film has a thickness less than or equal to 1 ⁇ , preferably less than or equal to 0.1 ⁇ .
• the support substrate may be a substrate of quartz, graphite, silicon, sapphire, ceramic, nitride, carbide, alumina or metal.
• the support substrate has, vis-à-vis the material of the two-dimensional film, a difference in thermal expansion coefficient lower than between the metal film and said two-dimensional film.
• the transfer of the metal film comprises:
• Said monocrystalline metal donor substrate is advantageously obtained by drawing an ingot.
• the method further comprises a step of forming an embrittlement zone in the donor substrate, so as to delimit the monocrystalline metal film to be transferred, and the thinning of the donor substrate comprises a detachment of the donor substrate along the weakened zone.
• the weakening zone is formed by implantation of atomic species in the donor substrate.
• the assembly of the donor substrate and the support substrate is implemented by gluing.
• the monocrystalline metal film is in the form of a plurality of blocks each transferred to the support substrate.
• Each block advantageously has the same area as the donor substrate, said area being less than the area of the support substrate.
• the growth substrate comprises a removable interface.
• Said interface can be configured to be disassembled by a laser lift-off technique, a chemical attack, or a mechanical stress.
• the method may comprise, after the growth of the two-dimensional film, a step of separating said two-dimensional film from the growth substrate.
• said separation may comprise a delamination of the interface between the monocrystalline metal film and the support substrate.
• said separation may comprise implantation of atomic species into the support substrate so as to form an embrittlement zone, and then detachment of the growth substrate along said embrittlement zone.
• the method comprises, after said separation, the transfer of a new monocrystalline metal film onto the support substrate, so as to form a new growth substrate, then the growth of a new two-dimensional film of a Group IV material having a hexagonal crystal structure on said novel growth substrate.
• said separation comprises a delamination of the interface between the two-dimensional film and the monocrystalline metal film of the growth substrate.
• the method comprises, after said separation, the reuse of the growth substrate to grow a new two-dimensional film of a group IV material having a hexagonal crystal structure on said substrate.
• the method may comprise, after the growth of the two-dimensional film, an etching of the metal film so as to transfer the two-dimensional film on the support substrate.
• the two-dimensional film is a graphene film.
• Another object of the invention relates to a structure obtained by the method which has just been described.
• Said structure successively comprises a support substrate, a monocrystalline metal film and a two-dimensional film of a Group IV material having a hexagonal crystalline structure on the metal film.
• the metal film is in the form of a plurality of blocks distributed on the surface of the support substrate.
• said two-dimensional film consists of one or more monatomic layers.
• the two-dimensional film is a graphene film.
• FIG. 1 illustrates a substrate for the growth of a graphene film according to one embodiment of the invention
• FIG. 2 illustrates a substrate for the growth of a graphene film according to an alternative embodiment of the invention
• FIGS. 3A to 3B illustrate the principal of a method of manufacturing the substrate of FIG. 1 according to one embodiment of the invention
• FIGS. 4A to 4B illustrate the main steps of a method of manufacturing the substrate of FIG. 2 according to one embodiment of the invention
• FIGS. 5A to 5B illustrate the main steps of a method of manufacturing the substrate of FIG. 2 according to an alternative embodiment of the invention
• FIG. 6 illustrates a structure comprising a graphene film formed by epitaxial growth on the substrate of FIG. 1;
• FIG. 7 illustrates a structure comprising a graphene film on a growth substrate comprising a removable interface
• FIG. 8 illustrates a structure in which the metal film of the growth substrate has been etched after growth of the graphene film.
• the following description relates to the growth of a graphene film, but the invention also applies to the other elements of group IV of the periodic table of elements which make it possible to form a two-dimensional film of crystalline structure.
• hexagonal namely silicon (the film material is called “silicene”), germanium (the film material is called “Germanian”) and tin (the film material is called “stanene”).
• FIG. 1 illustrates a substrate 100 for the growth of a graphene film according to one embodiment of the invention.
• Said substrate comprises a monocrystalline metal film 1 adapted for the growth of graphene, on a support substrate 2.
• Said substrate is obtained by transfer of the metal film onto the support substrate from a donor substrate.
• This transfer can be carried out by the Smart Cut TM process as described below, but other transfer processes involving an assembly of the donor substrate on the support substrate and then a thinning of the donor substrate until the thickness is obtained. desired for the metal film can be implemented.
• the metal film 1 comprises at least one of the following metals: nickel, copper, platinum, cobalt, chromium, iron, zinc, aluminum, iridium, ruthenium, silver.
• the film may consist of an alloy of said metals, or even an alloy comprising at least one of said metals and at least one other metal.
• the thickness of the monocrystalline film is advantageously less than or equal to 1 ⁇ , preferably less than or equal to 0.1 ⁇ .
• This thickness is typically at least 10 times lower than the thickness of metal foils conventionally used for the growth of graphene.
• the absorption effect of the atoms mentioned above is therefore considerably reduced, especially in the case of nickel for which the absorption phenomenon occurs throughout the thickness of the film.
• Such a thickness is sufficient to fulfill the main function of the metal film, which is to constitute a seed layer for the growth of graphene.
• the monocrystalline nature of the metal film makes it possible to form a graphene film having excellent crystalline quality.
• the metal film has little influence on the thermal expansion of the substrate during the growth of the graphene film, said thermal expansion being essentially due to the thermal expansion of the support substrate.
• the support substrate 2 has the main function of mechanically supporting the metal film during the growth of the graphene film.
• the material of the support substrate 2 must therefore withstand the conditions (in particular temperature and chemical environment) of the growth of the graphene film, which may vary according to the deposition technique chosen.
• chemical vapor deposition is carried out at a higher temperature than molecular beam epitaxy (MBE), the acronym for the term "Molecular Beam Epitaxy”.
• the material of the support substrate 2 is chosen to have, vis-à-vis the graphene, a difference in coefficient of thermal expansion lower than between the metal film and graphene.
• the difference in coefficient of thermal expansion between graphene and the material of the support substrate is minimized, it being recalled, however, that the difference in the coefficient of thermal expansion between the graphene and the substrate substrate material is all the more acceptable if the graphene growth temperature is low.
• the support substrate 2 is advantageously monocrystalline because this configuration is more favorable for polishing the surface of said substrate before the transfer of the metal film (when this transfer involves bonding), but this property is not imperative.
• the support substrate may optionally be formed by deposition.
• the preferred materials for the support substrate include quartz, graphite, silicon, sapphire, ceramics, nitrides, carbides, alumina, and metals.
• the support substrate may have, at the interface with the metal film, an encapsulation layer (not shown) intended to promote adhesion between the metal film and the support substrate, and / or to form a diffusion barrier to prevent pollution of graphene by elements of the support substrate.
• the material of the support substrate may in some cases show signs of decomposition or deterioration when it is directly exposed to the growth atmosphere of the graphene film, or when exposed to the conditions of assembly of the film. metallic.
• a diffusion barrier also makes it possible to eliminate or limit these effects.
• Said encapsulation layer may for example be formed of one of the following materials among oxides, nitrides and carbides.
• the metal film is not necessarily continuous on the surface of the support substrate.
• the metal film 1 may be formed of a set of monocrystalline metal blocks 10 distributed on the surface of the support substrate 2, said blocks 10 being contiguous or distant from each other, as shown in FIG.
• these blocks make it possible to exploit small metal monocrystals with respect to the dimension of the support substrate.
• dimension here means the area of the surfaces in contact with the blocks and the support substrate.
• the pavers are advantageously rectangular, but this form is not limiting.
• these blocks can also be in the form of bands, disks, hexagons, etc. Those skilled in the art are able to determine the shape of the blocks and their distribution on the surface of the support substrate depending on the geometry of the donor substrates at its disposal and the area of the graphene film to be formed.
• the monocrystalline metal film 1 is copper and the support substrate 2 is a silicon substrate successively covered with a film of 0.4 ⁇ of Si0 2 and a film of 0.1 ⁇ of copper intended for ensure a direct Cu / Cu metal bonding between the support substrate 2 and the metal film 1.
• Example 2
• the monocrystalline metal film 1 is nickel and the support substrate 2 is a molybdenum substrate, each being covered with a film of 0.2 ⁇ of copper intended to ensure a direct Cu / Cu metal bonding between the substrate support 2 and the metal film 1.
• the monocrystalline metal film 1 is nickel and the support substrate 2 is a polycrystalline AlN ceramic coated successively with a film of 0.3 ⁇ of Si 3 N 4 and a film of 0.5 ⁇ of Si0 2 .
• the monocrystalline metal film 1 is copper and the support substrate 2 is sapphire coated with a film of 0.3 ⁇ of Si0 2 .
• the monocrystalline metal film 1 is copper and the support substrate 2 is a 20 ⁇ thick polycrystalline copper film assembled by direct Cu / Cu metal bonding on a donor substrate after formation of an embrittlement zone. implantation in this one.
• the monocrystalline metal film 1 is copper and the support substrate 2 is a nickel film deposited by electrolytic deposition up to a thickness of 15 ⁇ directly on a donor substrate after formation of an embrittlement zone by implantation in this one.
• the monocrystalline metal film 1 is copper and the support substrate 2 is a nickel-copper alloy film electroplated to a thickness of 15 ⁇ directly on a donor substrate after formation of an embrittlement zone. by implantation in it.
• the monocrystalline metal film 1 is a nickel-copper alloy and the support substrate 2 is a nickel film electroplated to a thickness of 15 ⁇ directly on a donor substrate after formation of an embrittlement zone. implantation in this one.
• the monocrystalline metal film 1 is in the form of a plurality of monocrystalline nickel blocks 10 positioned contiguously on a plane support and the support substrate 2 is a nickel film deposited directly on a weakened face by implantation. of the plurality of blocks, the deposition of said nickel film being performed by electrolytic deposition to a thickness of 10 ⁇ .
• a donor substrate 1 1 formed of a single crystal metal.
• An embrittlement zone 12 in the donor substrate is formed by implantation of atomic species (schematized by the arrows), said weakening zone delimiting, on the surface of the donor substrate 11, the monocrystalline metal film to be transferred onto the support substrate.
• Said atomic species may in particular comprise hydrogen.
• Helium is another species particularly interesting from this point of view, replacing hydrogen or in combination with hydrogen.
• the donor substrate 11 is assembled on a support substrate 2, the metal film to be transferred being at the bonding interface.
• this assembly is made by bonding substrates 2 and 1 1.
• this assembly is carried out by depositing the support substrate 2 on the donor substrate 1 1, by any suitable deposition technique depending on the nature of the support substrate.
• the donor substrate is detached along the embrittlement zone 12, said detachment being capable of being initiated, for example, by mechanical, chemical, and / or thermal stress.
• This detachment results in the transfer of the monocrystalline metal film 1 onto the support substrate 2.
• the structure shown in FIG. 1 is thus obtained.
• a finishing treatment of the surface of the monocrystalline metal film is carried out, in order to make it suitable for the subsequent deposition of the graphene film.
• This may be for example a polishing operation, annealing and / or etching.
• This method of transferring the metal film comprises variants.
• a first variant relates to the mode of assembly of the donor substrate and the support substrate.
• the assembly can consist of a deposition of the support substrate on the donor substrate, the film to be transferred lying on the side of the donor substrate on which the deposit is made.
• a diffusion barrier layer is formed between the donor substrate and the support substrate to prevent diffusion of undesirable species from the support substrate to the graphene layer during growth thereof.
• a second variant - possibly combinable with the first - relates to the mode of thinning of the donor substrate to transfer the metal film on the support substrate.
• the blocks are assembled successively and then transferred collectively to the support substrate.
• a donor substrate 1 1 formed of a single metal crystal, whose area is smaller than that of the support substrate 2 intended to receive it.
• a weakening zone 12 is formed in the donor substrate 11.
• a first donor substrate 11 is then glued to the support substrate 2.
• a second donor substrate 1 1 is bonded to the support substrate 2, and this assembly operation is continued until the bonding of all the donor substrates required to obtain all the pavers on the support substrate 2.
• said donor substrate is detached along the zone of weakness to transfer a first monocrystalline metal pad on the support substrate, and this sequence is repeated with a subsequent donor substrate until the transfer of all the blocks 10 onto the support substrate 2.
• the donor substrate may optionally be the same as that in which the pad 10 has been removed, and thus be used repeatedly to transfer a pad on the same support substrate 2.
• the donor substrate may be different from that in which block 10 has been removed.
• all donor substrates 1 1 can be reused to achieve a new cycle. Recycling operations may be desirable or even necessary. For example a polishing operation will start from a surface roughness adequate assembly of good quality.
• the new donor substrate 1 1 is shown remote from the already transferred pad 10, it could be positioned contiguously to the pad 10 already transferred.
• the blocks 10 are assembled and transferred collectively on the support substrate 2.
• a plurality of donor substrates 11 are assembled on an intermediate substrate 13, the said intermediate substrate serving essentially as mechanical support or as a handling tool for the donor substrates 1.
• the donor substrates 1 1 are shown distant from each other, but they could also be juxtaposed contiguously.
• a weakening zone 12 is formed in each donor substrate, before or after their assembly on the intermediate substrate 13, so as to delimit a block 10 to transfer the support substrate.
• the intermediate substrate 13 carrying the donor substrates 11 is bonded to the support substrate 2, the free surface of the donor substrates 11 being at the bonding interface.
• the detachment step is performed collectively, for all the donor substrates.
• the detachment step can be carried out successively for each donor substrate.
• the intermediate substrate 13 carrying the remainder of the donor substrates may be recycled for a new collective transfer of blocks.
• the free surface of the donor substrates is treated to remove defects related to detachment, a new weakening zone is formed in all the donor substrates, and the intermediate substrate carrying the weakened donor substrates is bonded to a new substrate support.
• the preparation of the blocks is organized upstream of the process for manufacturing the growth substrate.
• metal ingots are assembled together before being cut collectively to form the donor substrates, then are collectively implanted before being assembled to the support substrate.
• the growth substrate having a continuous or discontinuous monocrystalline metal film is then used for the growth of a graphene film.
• CVD chemical vapor deposition
• MBE molecular beam epitaxy
• Figure 6 shows a graphene film 3 formed on a growth substrate 100.
• the graphene film advantageously consists of one or more monatomic layers of graphene, said layers being complete (i.e. continuous over the entire surface of the metal film) or not.
• This quality control of the graphene film is made possible not only by the parameters of the graphene deposition process but also by the excellent crystalline quality and / or the small thickness of the metal film which serves as a seed for the growth of graphene.
• the precise control of the number of monoatomic layers formed is based on the fact that the carbon atoms constituting the graphene layer come solely from the deposition atmosphere and not from the growth substrate itself.
• the monocrystalline film used in the invention is of better quality than the copper foils used in the state of the art, which are polycrystalline. Insofar as the presence of grain boundaries or other crystalline defects is minimized in the copper film according to the invention, the absorption sites of the carbon atoms are thus minimized.
• the superior quality of the monocrystalline film used in the invention has the same advantage as in the case of copper, to which is added a minimum volume for the absorption of carbon atoms, due to the thickness significantly reduced monocrystalline film compared to the usual sheets used.
• the support substrate 2 is chosen to have a small difference in coefficient of thermal expansion vis-à-vis the graphene film (the monocrystalline metal film being sufficiently thin to have a negligible influence)
• the Mechanical stresses applied to the graphene film during its cooling are minimized. This avoids or reduces the phenomena of relaxation or damage to the graphene film. This also contributes to a better quality of the graphene film.
• the metal film of the invention is monocrystalline makes it possible to control the orientation (for example 1 1 1) of the graphene film over the entire surface of the metal film.
• the graphene film After the formation of the graphene film, it can be separated from the growth substrate, to be transferred to another medium or not.
• This separation can be done in different ways.
• the growth substrate comprises a removable interface, that is to say an interface at which the application of a bias (or a treatment) allows detachment of two parts of the substrate. It is necessary here to hear the term interface in the broad sense, in particular in that it can contain one or more layers of non-zero thickness.
• any separation technique known in the field of microelectronics can be employed, the person skilled in the art being able to select the appropriate materials according to the chosen technique.
• Said removable interface may be located between the monocrystalline metal film and the support substrate, or located inside the support substrate.
• FIG. 7 thus illustrates an embodiment in which the removable interface I is located within the support substrate 2.
• said interface I may consist of a bonding interface, a region of a material adapted to confine a mechanical fracture, such as a porous layer (for example made of silicon), a layer allowing selective etching with respect to on the other hand, an embrittlement zone formed by implantation in the support substrate, etc.
• the separation of the graphene film from the growth substrate can be based on any disassembly technique known in the graphene field.
• the disassembly of the graphene film comprises a delamination of the interface between the metal film and the support substrate, and optionally a chemical etching of the metal film.
• the support substrate can be reused for the transfer of a new metal film, to form a new substrate for the growth of graphene.
• the disassembly of the graphene film comprises a delamination of the interface between the graphene film and the metal film.
• a delamination technique is described in [Wang 201 1], in the case of a growth substrate consisting of a copper sheet.
• the growth substrate can be reused for the growth of a new graphene film.

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