Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
  • H01L31/1892—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof methods involving the use of temporary, removable substrates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
  • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
  • H01L31/0687—Multiple junction or tandem solar cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
  • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
  • H01L31/0693—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells the devices including, apart from doping material or other impurities, only AIIIBV compounds, e.g. GaAs or InP solar cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
  • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
  • H01L31/184—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIIBV compounds, e.g. GaAs, InP
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
  • H01L31/1892—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof methods involving the use of temporary, removable substrates
  • H01L31/1896—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof methods involving the use of temporary, removable substrates for thin-film semiconductors
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/544—Solar cells from Group III-V materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/547—Monocrystalline silicon PV cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to a method of manufacturing a multijunction structure for a photovoltaic cell, the multijunction structure comprising at least a first junction and at least a second junction interconnected by a bonding interface. It also relates to a multijunction structure for a photovoltaic cell.
• multijunctions comprising 4 to 6 junctions each for absorbing a wavelength range of the solar spectrum.
• these solar cells can be made by making junctions on each other by epitaxy of materials formed of alloys based on, inter alia, In, P, As, and Ga.
• the exact composition of the alloys forming each of the junctions is extremely important.
• compositions of materials corresponds to a crystal lattice parameter of the junction.
• the epitaxial growth junction stack relies on a compromise between the composition of the junctions concerned, and the matching of the mesh parameter between each of these junctions, which limits the possibilities of stacking a large number of junctions from different materials.
• a composition junction "a” can not necessarily be made on a junction "b” if the mesh parameters of the different materials considered are too far apart and homo-epitaxial growth of very good quality can not be ensured. .
• a promising alternative to this method of manufacture is to superpose separately produced junctions by implementing direct bonding technology also known as molecular bonding technology.
• This technology must respect two important criteria: the optical transparency of the assembly of the junctions so that the solar radiation can cross the stack and be collected by each of the junctions superimposed, and electrical conduction between the junctions to allow the collection of the current generated in each of the junctions with a minimum of resistance, and therefore losses.
• the quality of the bonding interface between two junctions is critical to obtain a direct bonding assembly that is of good quality.
• the topology of the surfaces to be assembled must in particular have a very high flatness with a long wavelength and a very low roughness with a short wavelength.
• the more the number of epitaxial layers increase the more the defectivity at the surface increases in terms of constraints (adaptation of the mesh parameters), epitaxial growth defects , roughness etc.
• more than ten layers of different composition must be made to obtain a final thickness of about one micrometer.
• this bonding layer does not disturb the proper functioning of the junctions, but it can however degrade the operation of the stack of junctions if it generates a pronounced optical absorption, blocking the transmission of photons in the lower junctions. It is then appropriate for the bonding layer to have as thin a thickness as possible, which is extremely difficult to control during a polishing thinning step, especially when it is desired to obtain a thickness of bonding layer of thickness typically less than 100 nanometers with very good uniformity over the entire substrate.
• the bonding layer in order to avoid a negative electrical impact, it is necessary for the bonding layer to have a low electrical resistivity.
• the implementation of direct bonding technology is accompanied by a sealing heat treatment to reduce the resistivity of the contact.
• heat treatment temperatures of the order of 500 ° C or 600 ° C, which can cause deterioration of the assembled junctions. Indeed, when the junctions are obtained under thermal epitaxial conditions of the order of 500 ° C to 600 ° C, they do not tolerate or little heat such a high budget.
• One of the aims of the invention is to overcome at least one of these disadvantages.
• the invention proposes a method for manufacturing a multijunction structure for a photovoltaic cell, the multijunction structure comprising at least a first junction and at least one second junction connected together by a bonding interface, the method comprising the steps of
• this method makes it possible to form a junction after direct bonding, also known as molecular bonding, so as to overcome the constraints associated with bonding. It is then possible to insert a sealing heat treatment step increasing the electrical conductivity of the bonding interface, before the epitaxy of the junction is made.
• difference in nature of material is meant in the present application a material whose chemical composition is different. This excludes differences obtained by doping.
• an AI2O3 sapphire support substrate has a material nature different from that of a second InP or GaAs layer.
• the respective surface topologies of the first seed layer and the second layer are adapted to allow direct bonding (or molecular bonding) between the two surfaces.
• the surfaces intended to be brought into contact for direct bonding are planar and have, for example, an arrow of less than 50 ⁇ for a substrate with a diameter of 100 mm. They also have a roughness typically less than 1 nanometer RMS.
• the first support substrate comprises a first detachment region allowing removal of the first support substrate so as to expose the first seed layer.
• the method comprises, before step a), a step j) consisting in implanting ionic species in the first donor substrate so as to form a weakening plane, forming the first detachment region and defining the other the first support substrate and the first seed layer, and the step d) of removing the first support substrate is performed by detaching the first support substrate at the weakening plane.
• a step j) consisting in implanting ionic species in the first donor substrate so as to form a weakening plane, forming the first detachment region and defining the other the first support substrate and the first seed layer
• the step d) of removing the first support substrate is performed by detaching the first support substrate at the weakening plane.
• the method comprises, before step a), a step k) consisting of carrying out, for example according to Smart Cut TM technology, the first seed layer on a first support substrate via a layer forming the first detachment region comprising a buried detachment layer.
• Step d) of removing the first support substrate is furthermore carried out by laser irradiation carried out at the absorption wavelength of the buried detachment layer.
• the support substrate is advantageously sapphire, the layer forming the first silicon oxide detachment region and the buried silicon nitride detachment layer so that the sapphire is transparent to the wavelength used during laser irradiation.
• step d) the first support substrate removed in step d) is recycled for reuse according to step j) or k) of the method.
• the first seed layer comprises an etching stop layer epitaxially grown on the surface of the first donor substrate and the process comprises, before step e) a step I) of thinning at least a portion of the first seed layer until to respectively reach the etch stop layer.
• the thinning step I) can be carried out by any type of material removal, for example carried out by chemical etching, polishing or plasma etching.
• the etch stop layer is particularly useful for limiting etching to at least a portion of the first seed layer transferred by removal of the first support substrate by Smart Cut TM.
• the epitaxy takes place on the remainder of the first seed layer formed by the etch stop layer.
• the etch stop layer may also make it possible to complete the removal of the first support substrate by plasma etching, polishing and / or chemical etching, or else by laser irradiation while allowing to obtain a thin and uniform layer thickness. on the entire surface.
• the process comprises, after step c), a step of applying a heat treatment, preferably carried out at a temperature of between 200 ° C. and 800 ° C., and more preferably carried out at a temperature between 300 ° C and 600 ° C, for example with treatment times between a few seconds and several hours, typically 3 hours.
• a heat treatment makes it possible to reinforce the direct bonding of the first layer with the second layer and to reduce the electrical resistivity of the bonding without damaging the first bond.
• the method comprises after step e) a step o) comprising the manufacture of the second junction in contact with the second layer.
• the second donor substrate comprises at least one second junction interposed between the second support substrate and the second layer.
• the multijunction structure is quickly obtained.
• This embodiment is particularly advantageous when the second junction is made of a material that is not very sensitive to the heat treatment of sealing the direct bonding or when the reinforcement of the direct bonding does not require the application of a very large thermal budget and also when the second layer is optically highly transparent so that its thickness has little effect on the absorption of the solar spectrum of the multijunction.
• the process comprises after step e) of epitaxy,
• the second support substrate comprises a second detachment region allowing the removal of the second support substrate so as to expose the second layer.
• the second layer comprises an etching stop layer epitaxially grown on the surface of the second donor substrate and prior to epitaxial step ee) of at least one second junction, the method comprises thinning at least a portion of the second layer until reaching the etch stop layer. It is thus possible to thin in a simple and reproducible way the second layer so as to reduce the optical absorption of the layers at the bonding interface.
• the etch stop layer may also complete the removal of the first support substrate by polishing, plasma etching and / or chemical etching, or by laser irradiation while allowing to obtain a thin and uniform layer thickness on the substrate. entire surface.
• the epitaxy in this case takes place on the remainder of the second layer formed by the etch stop layer.
• the process comprises, before step b), a step jj) consisting in implanting ionic species in the second donor substrate so as to form a weakening plane, forming the second detachment region and delimiting on both sides other the second support substrate and the second layer and the dd) removal step of the second support substrate comprises a detachment at the weakening plane delimiting the second layer and the second support substrate.
• the method comprises, before step b), a step kk) consisting in bonding the second layer to a second support substrate, for example made of sapphire, by means of a layer, for example made of silicon oxide, forming the second detachment region, comprising a buried detachment layer, for example silicon nitride, and the dd) removal step of the second support substrate comprises a laser irradiation step of the buried silicon nitride detachment layer.
• the second support substrate can be easily removed and recycled for further use.
• the etch stop layer may also complete the removal of the second support substrate after laser irradiation, as after mechanical, plasma and / or chemical etching of the second support substrate, while allowing to obtain a thin layer thickness and uniform over the entire surface.
• the first seed layer and the second layer each consist of a monocrystalline semiconductor material selected from Ge and alloys based on at least one of In, P, As and Ga.
• these layers serve as seed for the epitaxy of at least one of the layers of a junction (they are then called seed layers), they consist of a material having a mesh parameter compatible with the epitaxial growth of the desired material for forming at least one of the layers of the junction.
• the nature of the material of the first seed layer and the second layer are chosen so that their mesh parameter is close to that of the at least one first junction and the at least one second junction, respectively.
• the mesh parameter of the first seed layer is close to that of the first junction so as to grow a monocrystalline material of very good quality.
• the process comprises, before step a) a step i) of epitaxial growth of the first seed layer on the first support substrate and / or of the second layer on the second support substrate.
• the first support substrate comprises on the surface a monocrystalline material whose mesh parameter is close to that of the first seed layer, it can then have a good quality (few dislocations, rough surface) and be monocrystalline for the epitaxy of the first junction.
• the invention proposes a method of manufacturing a photovoltaic cell comprising a multijunction structure manufactured as previously described.
• the invention proposes a method of manufacturing a photovoltaic system comprising a photovoltaic cell manufactured as previously described.
• the invention proposes a multijunction structure comprising at least one first junction and at least one second junction connected by a bonding interface having a thickness of less than 200 nanometers, an electrical resistivity of less than 50 mohm.cm 2, and a conversion efficiency greater than 40%.
• FIGS. 6 to 10 illustrate a variant of the embodiment previously illustrated.
• FIG. 1 1 to 18 illustrate a second embodiment of the method according to the invention.
• FIG. 1 illustrates a step j) of the process consisting in implanting ionic species, for example with a dose of between 10 E 16 and 10 E 17 at / cm 2 of hydrogen-based ions, in a first donor substrate 1 of Ge, GaAs or InP, so as to form an embrittlement plane 2, forming the first detachment region and delimiting a first support substrate 3 and a first seed layer 4.
• the implantation conditions allow to create a weakening plane 2 at a shallow depth of up to 1 nm in the donor substrate 1 so that the first seed layer 4 is very thin.
• the first donor substrate 1 provided for direct bonding according to step a) of the method.
• FIG. 2 illustrates a step b) of the method of providing a second donor substrate 5 comprising a second support substrate 6, a second layer 7 and a second junction 8 interposed between the second support substrate 6 and the second layer 7.
• the topologies of the surface of the first seed layer 4 and the second layer 7 have been prepared beforehand so as to have a roughness of less than 1 nanometer RMS and a flatness adapted to direct bonding of the order of 50 ⁇ for a 100 mm substrate between the two layers 4.7.
• FIG. 3 illustrates step c) of the method consisting in bringing the first seed layer 4 and the second layer 7 into contact to form a bonding interface 9 and obtaining direct bonding.
• FIG. 4 illustrates the removal of the first support substrate 3 by detachment at the embrittlement plane 2.
• the first seed layer of small thickness is thus exposed so as to produce an epitaxy of a first junction January 1 on its surface (FIG. ).
• a multijunction structure 12 is thus obtained by direct bonding comprising at least a first seed layer 4 also serving as a thin bonding.
• a heat sealing treatment of the direct bonding at 300 ° C. for a typical duration ranging from a few seconds to 120 min for example is applied to the structure before the epitaxy is made so as to reduce the electrical resistivity. (typically less than 50 mohm.cm 2 of the contact obtained without damaging the second junction 8.
• step d) of removing the first support substrate 3 is carried out by applying a heat treatment typically at a temperature of 100-350 ° C and for a duration of between 30 min and 120 min allowing both the development of the cavities at the weakening plane leading to the detachment of the first support substrate 3 and also the strengthening of the seal decreasing the electrical resistivity of the bonding.
• step d) of removing the first support substrate 3 is obtained by applying a mechanical stress at the level of the weakening plane 2 so as not to damage the second junction 8.
• a heat treatment can be applied in addition to the mechanical stress to obtain the detachment of the first support substrate 3, this heat treatment then participates in the sealing favoring the reduction of the resistivity of the bonding interface 9.
• Figures 6 to 10 illustrate a manufacturing method which differs from that illustrated in Figures 1 to 5 in that the first seed layer 4 comprises an etching stop layer 13 at the surface of the first donor substrate 1 ( Figure 6).
• This etching stop layer 13 is formed beforehand by epitaxialization of a material having a reactivity different from the other part of the first seed layer 4 facing etching (chemical, mechanical or plasma).
• This etch stop layer 13 obtained by epitaxy is monocrystalline has a small uniform thickness and can be used as seed for the epitaxy of the first junction 11.
• the first donor substrate 1 is a solid InP substrate comprising at the surface an etching stop layer 13 of InGaAs at the mesh parameter adapted to the subsequent growth of at least one junction.
• Ion implantation based on hydrogen, helium or other gaseous species forms a weakening plane 2 in the InP substrate 1 which delimits the first InP support substrate 3 and a first InP seed layer 4 comprising at the surface of the etching stop layer 13 of InGaAs.
• After the detachment of the first support substrate 3 and at least a part of the first seed layer 4 is removed for example by etching, polishing or plasma, until reaching the etching stop layer 13.
• an epitaxy of a first InGaAs junction 1 1 is followed by the epitaxy of an additional InGaAsP junction to obtain a multi-junction structure 12.
• FIGS 12 to 18 illustrate an alternative embodiment of the method according to the invention.
• FIG. 11 illustrates a first donor substrate 1 comprising a first GaAs seed layer 4 bonded to a first support substrate 3 made of sapphire material (step k) via a silicon oxide layer 14 forming the first detachment region, comprising a silicon nitride layer (not shown).
• This prior gluing step may have been performed by Smart Cut TM technology to obtain a first seed layer 4 with a controlled thickness of about 50 nanometers.
• FIG. 12 illustrates a second donor substrate 5 comprising a second seed layer 7 made of InP having a thickness of approximately 50 nanometers bonded to a second support substrate 6, for example made of sapphire material, by means of bonding layers ( silicon oxide, silicon nitride, etc.) 14 forming the second region of detachment comprising at least one buried layer of detachment of silicon nitride (not shown) (step kk).
• bonding layers silicon oxide, silicon nitride, etc.
• FIG. 13 illustrates the bringing into contact of the first seed layer 4 and of the second layer 7, the surfaces of which have been prepared beforehand in order to obtain surface topologies suitable for direct bonding (step c). Then a heat sealing treatment of the direct bonding is applied at 600 ° C for a few seconds to 2 hours to improve the electrical conductivity of the bonding interface 9 to less than 50 mohm.cm 2 .
• Figure 14 illustrates step d) of removing the first sapphire support substrate 3 by laser irradiation therethrough at the absorption wavelength of the silicon nitride. This absorption generates the degradation of the silicon nitride layer, which allows the detachment of the support substrate 3. It can advantageously be recycled for a new use in a subsequent process.
• FIG. 15 illustrates the step e) of producing an epitaxy of at least a first junction 1 1 made of AIGaAs or GaAs material on the first exposed GaAs seed layer 4 after cleaning the residues of the silicon oxide layer 14 .
• the first junction 1 1 is secured to a host substrate 15 such as a semiconductor substrate (Si, Ge, etc.), metal (Mo, Cu, etc.) or insulator (glass, Sapphire, etc.) (FIG. 16 step m) so as to be able to remove the second support substrate 6 (step dd).
• a host substrate 15 such as a semiconductor substrate (Si, Ge, etc.), metal (Mo, Cu, etc.) or insulator (glass, Sapphire, etc.)
• This shrinkage is in particular carried out by laser irradiation as previously described (FIG. 17).
• an epitaxy of at least one second junction 8 is produced so as to obtain a multi-function structure 12 having a thickness at the bonding interface 9 less than 200 nanometers and an electrical resistivity lower than 50 mohm.cm 2 (step ee).
• the second donor substrate 5 comprises two junctions 8.8 'interposed between the second support substrate 6 and the second layer 7.
• Step d) of the process comprises the epitaxy of two junctions 11, 11 'or even an epitx of three junctions.
• the second donor substrate 5 comprising a second junction 8 is previously bonded with a second second donor substrate 5 comprising another junction 8 '.
• step c) of the process three junctions 11, 11 'and 11''are epitaxially grown on the first seed layer 4 according to step d) of the method.
• the present invention thus makes it possible to envisage all the possible combinations of bonding of several junctions and of epitaxies of several junctions making it possible to obtain multi-function structures comprising 4, 5 or even 6 junctions having weakly optically absorbing bonding interfaces 9 and presenting a very good electrical conductivity.
• the present invention proposes the manufacture of a multijunction structure 12 comprising at least a first and at least a second junction 8.1 1 connected by a bonding interface 9 simple to implement, preserving the integrity of the layers of junctions 8.1 1 and which provides a bonding interface 9 weakly optically absorbing and very good electrical conductivity.

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