METHOD FOR PRODUCING A THERMOELECTRIC STRUCTURE

Description

TECHNICAL FIELD

[0001] The present invention relates to the general field of thermoelectric modules. The invention relates to a method for manufacturing thermoelectric structures. The invention also relates to a thermoelectric structure obtained by such a method.

[0002] The invention also relates to thermoelectric devices comprising two thermoelectric structures thus obtained, one being of a first type of conductivity and the other being of a second type of conductivity.

[0003] The invention finds applications in many industrial fields, and in particular for applications requiring thermoelectric generators, where a thermal gradient is available (e.g. transport, industries, etc.), radioisotope thermoelectric generator applications, Peltier applications or even thermal sensor applications.

[0004] The invention is particularly interesting since it makes it possible to form thermoelectric structures / devices with low resistivities. STATE OF THE PRIOR ART

[0005] Generally, thermoelectric (TE) modules comprise a set of first pads made of a thermoelectric material of a first conductivity type and a set of second pads made of a thermoelectric material of a second conductivity type. For example, the first material is an N-type material (i.e., N-type conductivity) and the second material is a P-type material (i.e., P-type conductivity).

[0006] The pads are electrically connected in series and thermally in parallel. The pads are connected to each other by metallic elements. Thermoelectric junctions are also called NP junctions. The pads are held by ceramic substrates arranged on either side of the pad assemblies.

[0007] The electrical performance of a TE device in generator mode is given by: an internal electrical resistance R int defined according to (1): R int = N × ρ np × L / A + R c + R met with N the number of NP junctions, ρ np the electrical resistivity of the NP materials, L the length of a line or thickness of a pad, A the section of a line or pad, R c the total resistance of the contacts and R met the total resistance of the metal junctions a useful electrical power Pu defined according to (2): Pu = V oc 2 / 4 R int with V oc the voltage generated by the TE module

[0008] Thus, to have high power, it is necessary to have low internal electrical resistance, and therefore reduce the contribution of the total resistance of the contacts R c and the total resistance of the metal junctions R met .

[0009] Conventionally, the manufacturing of TE modules is generally carried out from the following stages: manufacturing of TE materials (sintering), shaping of the pads, metallization of the pads, assembly with the substrates.

[0010] The metal connections are made directly on the substrates, for example using the so-called direct copper (or DBC for 'Direct Bonding Copper') technique, then brazing and pressing with the pads.

[0011] However, this manufacturing process is relatively complex and greatly limits the geometry and modularity of the manufactured thermoelectric device.

[0012] There are also substrate-less TE modules, also called "skeleton modules." These modules therefore have no thermal loss due to the substrates. However, they cannot come into contact with electrically conductive surfaces.

[0013] It is also possible to use TE pads made from multiple TE materials. These so-called segmented pads can accommodate a greater temperature difference at the ends of the module because the materials used are generally optimized for different temperature ranges. WO 2020 / 066948 A1 (AISIN TAKAOKA LTD [JP]) April 2, 2020 (2020-04-02) discloses a method for manufacturing a thermoelectric structure comprising providing a substrate made of a first material and depositing a thermoelectric element made of a second material on the substrate, by additive manufacturing. STATEMENT OF THE INVENTION

[0014] An aim of the present invention is to propose a method for manufacturing thermoelectric structures, which is simple to implement and makes it possible to manufacture thermoelectric structures having good electrical properties (in particular, low contact resistance) and / or good thermal properties.

[0015] For this, the present invention proposes a method of manufacturing a thermoelectric structure comprising the following steps: a) providing a substrate made of a first material, b) depositing a thermoelectric element made of a second material on the substrate, by additive manufacturing, c) thinning and cutting the substrate, until a film made of the first material is obtained, whereby a thermoelectric structure is obtained comprising a film made of the first material and the thermoelectric element.

[0016] The invention fundamentally differs from the prior art by the implementation of a step during which the functionalization (metallization) of the thermoelectric element (for example a thermoelectric pad) is carried out during the additive manufacturing process.

[0017] This leads not only to a significant reduction in the number of steps and therefore to a simplification of the process compared to prior art processes, but also to a considerable saving of time and a reduction in costs.

[0018] The metallization obtained has good mechanical strength and good electrical and / or thermal conduction properties.

[0019] Preferably, the additive manufacturing technique is a powder bed fusion (PBF) or a selective laser sintering (SLS). Advantageously, the substrate is covered, completely or locally, by a metal bonding layer made of a third material and the thermoelectric element is formed on the metal bonding layer, whereby a thermoelectric structure is obtained comprising a film, a bonding layer and a thermoelectric element, the third material preferably being selected from Al, Ti, Cu, Au and Ni.

[0020] According to an advantageous embodiment, the thermoelectric element is a part having the shape of a comb delimiting a base and a plurality of branches, substantially parallel to each other, extending substantially orthogonally from the base, the plurality of branches having a first end and a second end, the first end being connected to the base, and the second end being in contact with the film or where appropriate in contact with the metal bonding layer.

[0021] According to another advantageous embodiment, the thermoelectric element is a pad, having a base and a height.

[0022] According to this other advantageous embodiment, the substrate can be cut so as to have a film having the same surface area as the surface area of ​​the base of the pad. Alternatively, the substrate can be cut so as to have a film having a surface area greater than the surface area of ​​the base of the pad.

[0023] Advantageously, during step b), several pads are deposited and the substrate is cut so as to have a structure comprising a film on which several pads are arranged.

[0024] Advantageously, between step b) and step c), the method comprises an additional step during which an intermediate metallization layer is deposited on the thermoelectric element, followed by an additional thermoelectric element made of a fourth material having a conductivity type opposite to the conductivity type of the second material. For example, the second material is of type N and the fourth material is of type P (or vice versa).

[0025] Advantageously, the second material is Si, SiGe, Bi 2 Te 3 , Half-Heusler or Skutterudites.

[0026] The fourth material can also be chosen from Si, SiGe, Bi 2 Te 3 , Half-Heusler and Skutterudites. For example, the second material is N-doped SiGe and the fourth material is P-doped SiGe.

[0027] Advantageously, the first material is 316L steel, aluminum, titanium, CuZr alloy, ceramic or graphite.

[0028] The process has many advantages: it has a low number of steps, it is simple and economical, it allows a great modularity of design of the manufactured thermoelectric device, for example, the thermoelectric elements can have simple shapes (a pad for example) or complex shapes (a comb for example).

[0029] The invention also relates to a thermoelectric structure obtained by such a method.

[0030] The thermoelectric structure comprises a film, for example made of 316L steel, aluminum, titanium, CuZr alloy, ceramic or graphite, on which one or more thermoelectric elements are arranged.

[0031] Advantageously, a metallic bonding layer, for example made of Al, Ti, Cu, Au or Ni, is placed between the film and the thermoelectric element(s).

[0032] Additive manufacturing allows for the creation of complex shapes that are not possible with current TE material manufacturing techniques. Complex shapes include, for example, circular shapes. It is also possible to create thermoelectric elements with cavities, or thermoelectric elements in the shape of a honeycomb or spiral. Square shapes, which are simpler to implement, are also possible.

[0033] The invention also relates to a thermoelectric device comprising two thermoelectric structures obtained by a method as described above, each thermoelectric structure comprising a film, for example made of 316L steel, aluminum, titanium, CuZr alloy, ceramic or graphite, and one or more thermoelectric elements, a metal bonding layer, for example made of Al, Ti, Cu, Au or Ni, being able to be arranged between the film and the thermoelectric element(s) of the two thermoelectric structures, the thermoelectric element(s) of one of the thermoelectric structures being of a first type of conductivity and the thermoelectric element(s) of the other thermoelectric structure being of a second type of conductivity opposite to the first type of conductivity.

[0034] Other characteristics and advantages of the invention will emerge from the additional description which follows.

[0035] It goes without saying that this additional description is given only as an illustration of the subject of the invention and must in no case be interpreted as a limitation of this subject. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be better understood by reading the description of exemplary embodiments given for purely indicative and non-limiting purposes with reference to the appended drawings in which: THE Fig. 1A, Fig. 1B and Fig. 1C represent, schematically and in section, the different stages of a method of manufacturing a thermoelectric structure according to a first embodiment of the invention. The Fig. 2A, Fig. 2B, Fig. 2C And Fig. 2D represent, schematically and in section, the different stages of a method of manufacturing a thermoelectric structure according to a second embodiment of the invention. The Fig. 3A, Fig. 3B, Fig. 3C,Fig. 3D and Fig. 3Erepresent, schematically and in section, the different stages of a method of manufacturing a thermoelectric device according to a third embodiment of the invention. The Fig. 4A,Fig. 4B,Fig. 4C,Fig. 4D,Fig. 4E and Fig. 4F represent, schematically and in section, the different stages of a method of manufacturing a thermoelectric device according to a fourth embodiment of the invention. The Fig. 5A, Fig. 5B and Fig. 5C represent, schematically and in section, the different stages of a method of manufacturing a thermoelectric structure according to a fifth embodiment of the invention. The Fig. 6A, Fig. 6B , Fig. 6C and Fig. 6D represent, schematically and in section, the different stages of a method of manufacturing a thermoelectric structure according to a sixth embodiment of the invention. The Fig. 7 is a photographic image of thermoelectric pads deposited on a substrate according to a particular embodiment of the invention.

[0037] The different parts represented in the figures are not necessarily on a uniform scale, to make the figures more readable.

[0038] The different possibilities (variants and embodiments) must be understood as not being mutually exclusive and can be combined with each other.

[0039] Furthermore, in the following description, terms that depend on the orientation, such as "above", "below", etc. of a structure apply with the assumption that the structure is oriented as illustrated in the figures. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0040] Although this is in no way limiting, the invention is particularly interesting for applications requiring thermoelectric generators (TEG or GTE for "ThermoElectric Generator"), where a thermal gradient is available (e.g. transport, industries, etc.), radioisotope thermoelectric generator applications (RTG or GTR for "Radioisotope Thermoelectric Generators") in particular for SiGe, Peltier applications or even thermal sensor applications. As shown in the Fig. 1A to 1C, 2A has 2D, 3A has 3E , 4A has 4F , 5A has 5C, 6A has 6D , the manufacturing process of a thermoelectric structure comprises the following steps: a) providing a substrate 100 made of a first material, b) depositing a thermoelectric element 200 made of a second material on the substrate 100, by additive manufacturing, preferably by selective laser sintering (SLS) or by powder bed laser fusion (PLF), c) thinning and cutting the substrate 100 until a film 101 made of the first material is obtained, whereby a thermoelectric structure is obtained comprising a film 101 made of the first material and the thermoelectric element 200.

[0041] The substrate 100 provided in step a) may be a tray or an over-tray.

[0042] In additive manufacturing machines, over-platens are attached directly to the plates, and allow not only to obtain thinner thicknesses (between 200µm and a few millimeters), but also to increase the nature of the usable materials. The over-platen is, advantageously, made of ceramic.

[0043] The substrate 100 is, for example, made of a metal (for example Al, Ti, Cu, Au or Ni), a metal alloy, a semiconductor material, ceramic or graphite. For example, it is made of 316L steel, aluminum, titanium, CuZr, ceramic or graphite.

[0044] The substrate 100 may have a thickness ranging from a few hundred micrometers to a few centimeters, and preferably from a few hundred micrometers to a few millimeters.

[0045] The thermoelectric element 200 deposited in step b) is made of a second material. The second material is preferably chosen from Si, SiGe, MnSi Bi 2 Te 3 , Half-Heusler and Skutterudites. Skutterudites are mineral species composed of cobalt and nickel arsenide of formula (Co, Ni)As 3-x with traces of S, Bi, Cu, Pb, Zn, Ag, Fe and Ni.

[0046] The thermoelectric element 200 may be of N-type conductivity to promote the movement of electrons (i.e. the material of which it is composed has a strictly negative Seebeck coefficient) or of P-type conductivity to promote the movement of holes (i.e. the material of which it is composed has a strictly positive Seebeck coefficient).

[0047] For example, N-type doped thermoelectric material is a silicon-germanium (SiGe) alloy doped with phosphorus or N-type doped polysilicon. The N-type dopant can be phosphorus or arsenic.

[0048] For example, the P-type material is a boron-doped silicon-germanium (SiGe) alloy or P-type doped polysilicon. The P-type dopant is preferably boron.

[0049] Advantageously, the dopant is integrated directly into the base powder.

[0050] The thermoelectric element 200 can be formed directly on the substrate 100. It is then in direct contact with the substrate 100.

[0051] According to an advantageous embodiment variant, the substrate 100 provided in step a) can be covered by a bonding layer 300 made of a third material. During step b), the thermoelectric element 200 is then formed on the metal bonding layer 300. It is directly in contact with this bonding layer 300. A thermoelectric structure is thus obtained comprising a film 101, a bonding layer 300 and a thermoelectric element 200.

[0052] The bonding layer 300 may locally or completely cover the substrate 100. For example, the metal bonding layer 300 forms a plurality of islands on the surface of the substrate 100. A thermoelectric element 200 may be formed on each island ( Fig. 2B , 3B , 6A) or several thermoelectric elements 200, 201 can be formed on each island ( Fig. 4B ).

[0053] To obtain a bonding layer 300 locally covering the substrate 100, it is possible to carry out a localized deposition of this layer. Alternatively, it is possible to carry out a full-plate deposition of a continuous layer followed by a step during which a portion of the continuous layer is removed, for example by etching, to form the islands.

[0054] The bonding layer 300 may be deposited, for example, by physical vapor deposition (PVD), evaporation, or sputtering. After the bonding layer 300 has been deposited, an annealing step may be performed.

[0055] The bonding layer 300 is made of a material different from that of the substrate 100.

[0056] The bonding layer 300 is, for example, made of metal or a metal alloy. Preferably, the metal is chosen from Al, Ti, Cu, Au and Ni. Several layers can be superimposed, for example, it can be a bilayer or a trilayer. A trilayer formed of a copper layer, a nickel layer and a gold layer can be chosen. By way of illustration and not limitation, it is possible to choose a trilayer formed of Cu (for example 200nm) + Ni (for example 5µm) + Au (for example 10nm). The thermoelectric element 200 deposited in step b) is obtained by additive manufacturing. The method consists of depositing the material in several successive passes on the substrate or on the bonding layer. At the end of the successive depositions, the thermoelectric element is obtained. The substrate can be a plate or an over-plate.

[0057] The additive manufacturing technique is preferably a powder bed laser fusion technique (FLLP or PBF for "Powder Bed Fusion" in English terminology) or a selective laser sintering technique ("SLS" which is the acronym for "Selective Laser Sintering") according to English terminology.

[0058] FLLP processes involve melting certain regions of a powder bed, for example using a laser beam.

[0059] In the SLS process, the powders are sintered. The powder materials do not pass into the liquid phase.

[0060] However, other additive manufacturing techniques can be considered, such as "Cold Spray", "Electron Beam Melting", etc.

[0061] The thermoelectric element 200 deposited in step b) can take several forms. According to a first advantageous embodiment, the thermoelectric element 200 is a comb-shaped part ( Fig. 5B ).

[0062] The part has the shape of a comb delimiting a base and a plurality of branches, substantially parallel to each other, extending substantially orthogonally from the base. The plurality of branches has a first end and a second end. The first end is connected to the base, and the second end is in contact with the film 101 or, where appropriate, in contact with the metal bonding layer 300.

[0063] By "substantially orthogonal" we mean "orthogonal" or "orthogonal to within plus or minus 10° tolerance".

[0064] By "substantially parallel" we mean "parallel" or "parallel to within plus or minus 10° tolerance".

[0065] According to another embodiment, the thermoelectric element 200 is a pad ( Fig. 1B, 2B , 3B , 4B , 6A ). The plot has a base with a surface and a height.

[0066] According to a particular embodiment, between step b) and step c), the method comprises an additional step during which an intermediate metallization layer 400 is deposited on the thermoelectric element 200 ( Fig. 6B ) then an additional thermoelectric element 500 in a fourth material ( Fig. 6C ). The fourth material is different from the second material.

[0067] After step b), thermal annealing can be carried out.

[0068] During step c), the substrate 100 is thinned and cut to form a film 200 facing the thermoelectric element 200.

[0069] The substrate 100 can be thinned by laser, mechanical machining, water jet, electroerosion or even by electrochemical machining.

[0070] The substrate 100 can be cut by laser, wire saw...

[0071] According to a first variant embodiment, during step c), the substrate 100 is cut so as to have a film 101 having the same surface as the surface of the base of the pad or of the second end of the branches of the comb.

[0072] According to another embodiment variant, during step c), the substrate 100 is cut so as to have a film 101 having a surface area greater than the surface area of ​​the base of the pad. Very advantageously, during step b), several pads 200, 201 are deposited ( Fig. 4B, 4D ) and the substrate 100 is cut so as to have a structure comprising a film 101 on which several pads 200, 201 are arranged ( Fig. 4C, 4E ).

[0073] At the end of step c), a first thermoelectric structure is thus obtained. Advantageously, the manufacturing method described above is implemented to manufacture a second thermoelectric structure (as for example shown in the Fig. 3D And4E ).

[0074] The second structure comprises a film 111 obtained after thinning and cutting the substrate 100 and one or more thermoelectric elements 210, 211. A bonding layer 310 may be arranged between the film 111 and the thermoelectric element(s) 210, 211.

[0075] The thermoelectric material of the second structure is of a different doping than that of the first structure.

[0076] The two structures obtained are advantageously assembled and electrically connected to form a thermoelectric device ( Fig. 3E And 4F ).

[0077] It is possible to connect the devices in series and / or in parallel. It is advantageous to combine series and parallel connections to optimize the electrical output performance of the manufactured thermoelectric device.

[0078] Where appropriate, the materials of the metal layers 300, 310 of the two structures may be identical or different. The materials of the substrates 100, 110 used may be different, identical or different.

[0079] The invention is particularly interesting for manufacturing conventional thermoelectric modules, DBC substrates, so-called skeleton thermoelectric modules or even segmented thermoelectric pads.

[0080] The resulting thermoelectric device can operate in Seebeck mode (i.e. the thermoelectric device is then a generator of electrical energy) or in Peltier mode (i.e. the thermoelectric device is then a generator of thermal energy).

[0081] We will now describe in more detail different embodiments with reference to the attached figures.

[0082] According to a first embodiment shown in Fig. 1A to 1C, the method comprises the following steps: a) providing a substrate 100 made of a first material, b) depositing a thermoelectric pad 200, and preferably several thermoelectric pads, made of a second material on the substrate 100, by additive manufacturing, preferably by SLS or FLLP, c) thinning and cutting the substrate 100, whereby one or more thermoelectric structures are obtained, each comprising a thermoelectric pad 200 covered by a film 101 made of the first material.

[0083] This first embodiment is advantageous because it allows the material of the substrate 100 (preferably metal or metal alloy) to be used directly for the metallization of the pads 200.

[0084] According to a second embodiment shown in the Fig. 2A to 2D , the method comprises the following steps: a) providing a substrate 100 made of a first material, locally covered by a metal bonding layer 300 made of a third material, forming islands, b) depositing a thermoelectric pad 200, and preferably several thermoelectric pads, made of a second material on each island of the bonding layer 300, by additive manufacturing, preferably by SLS or FLLP, c) thinning and cutting the substrate 100, whereby several thermoelectric structures are obtained, each comprising a thermoelectric pad 200 successively covered by a bonding layer 300 and a film 101 made of the first material.

[0085] This second embodiment is advantageous because it allows the material of the substrate 100 (plate) to be used directly for the metallization of the pads 200, the mechanical strength of the metallization being improved by the presence of the bonding layer 300.

[0086] In these first embodiments, the substrate 100 is cut to the size of the pads 200.

[0087] According to an alternative embodiment, the substrate 100 can be cut so as to have a surface area greater than the surface area of ​​the base of the pads 200.

[0088] For example, according to a third embodiment, shown in Fig. 3A to 3C , the method comprises the following steps: a) providing a substrate 100 made of a first material, locally covered by a metal bonding layer 300 made of a third material, forming islands, b) depositing a thermoelectric pad 200, made of a second material on the substrate 100, by additive manufacturing, preferably by SLS or FLLP, on each island, c) thinning and cutting the substrate 100, whereby several structures are obtained, each comprising a film 101 made of a first material covered by a bonding layer 300 then by a thermoelectric pad 200.

[0089] Advantageously, the same method is implemented to manufacture other thermoelectric structures each comprising a film 111 made of a first material covered by a bonding layer 310 then by a thermoelectric pad made of a fourth material of conductivity opposite to the conductivity of the second material ( Fig. 3D ). The two devices are then assembled to form, preferably, skeleton modules ( Fig. 3E ).

[0090] For example, according to a fourth embodiment, shown in Fig. 4A to 4C , the method comprises the following steps: a) providing a substrate 100 made of a first material, locally covered by a metal bonding layer 300 made of a third material, forming islands, b) depositing several thermoelectric pads 200, 201, made of a second material on each island of the metal bonding layer 300, by additive manufacturing, preferably by SLS or FLLP, c) thinning and cutting the substrate 100, whereby a structure is obtained comprising a film 101 made of a first material covered by a bonding layer 300, on which several thermoelectric pads 200, 201 are arranged.

[0091] Advantageously, the same method is implemented to manufacture an additional structure from a substrate 110, locally covered by a metal bonding layer 310 on which several pads 210, 211 are formed by additive manufacturing ( Fig. 4D to 4F ).

[0092] This additional structure comprises a film 111 covered by a bonding layer 310 on which are arranged several thermoelectric pads 210, 211 of conductivity opposite to the conductivity of the pads 200, 201 of the first structure ( Fig. 4E ). The two devices are then assembled to form, preferably, skeleton modules ( Fig. 4F ).

[0093] This fourth embodiment is particularly interesting because it allows series / parallel connections to be combined and thus optimizes the electrical output performance. Indeed, it is possible to electrically connect the different thermoelectric pads in any way. Usually, all the pads are electrically connected in series. But this can lead to high output voltages (of several volts), which is incompatible with associated electronics ("power management unit") for which the voltages are generally a few volts. This embodiment allows certain pads to be connected in parallel while reducing the output voltage, and while maintaining the generated power.

[0094] According to a fifth embodiment shown in the Fig. 5A to 5C , the method comprises the following steps: a) providing a substrate 100 made of a first material, covered by a metal bonding layer 300 made of a third material, b) forming a thermoelectric part 200 in the shape of a comb, made of a second material on the metal bonding layer 300, by additive manufacturing, preferably by SLS or FLLP, the part being a comb, c) thinning and cutting the substrate 100, and cutting the bonding layer 300, whereby a comb 200 is obtained, the second end of the branches of which is covered by a bonding layer 300 and a film 101 made of the first material.

[0095] The same process is used to make a comb of a conductivity type opposite to the conductivity type of the second material. The two combs are then assembled.

[0096] According to a sixth embodiment shown in the Fig. 6A to 6D , the method comprises the following steps: a) providing a substrate 100 made of a first material, locally covered by a bonding layer 300, forming islands, b) depositing a thermoelectric pad 200 made of a second material on each island of the bonding layer 300, by additive manufacturing, preferably by SLS or FLLP, then a metallization layer 400 and another thermoelectric element 500 made of a fourth material, c) thinning and cutting the substrate 100, until a film 101 made of a first material is obtained, whereby thermoelectric structures are obtained each comprising a film 101, a bonding layer 300, a first thermoelectric pad 200, a metallization layer 400 then a second thermoelectric pad 500.

[0097] This embodiment is particularly advantageous for manufacturing segmented thermoelectric pads. Illustrative and non-limiting examples of an embodiment :

[0098] In this example, SiGe thermoelectric elements, in the form of a pad, were fabricated by SLS. The thermoelectric elements can have a thickness of 500 µm to a few centimeters.

[0099] The tray is made of 316L stainless steel.

[0100] There Fig. 7 represents thermoelectric elements thus manufactured.

Claims

1. A method for manufacturing a thermoelectric structure comprising the following steps: a) providing a substrate (100) made of a first material, b) depositing a thermoelectric element (200) made of a second material on the substrate (100), by additive manufacturing, preferably by selective laser sintering or by laser powder bed fusion, c) thinning and cutting the substrate (100), until a film (101) made of first material is obtained, whereby a thermoelectric structure comprising a film (101) and the thermoelectric element (200) is obtained.

2. The method according to the preceding claim, characterised in that the substrate (100) is covered, completely or locally, by a metallic bonding layer (300) made of a third material and in that the thermoelectric element (200) is formed on the bonding layer (300), whereby a thermoelectric structure comprising a film (101), a bonding layer (300) and a thermoelectric element (200) is obtained, the third material preferably being selected from Al, Ti, Cu, Au and Ni.

3. The method according to claim 1 or 2, characterised in that the thermoelectric element (200) is a part having the shape of a comb delimiting a base and a plurality of branches, substantially parallel to each other, extending substantially orthogonally from the base, the plurality of branches having a first end and a second end, the first end being connected to the base, and the second end being in contact with the film (101) or, where appropriate, in contact with the metal bonding layer (300).

4. The method according to claim 1 or 2, characterised in that the thermoelectric element (200) is a pad, having a base and a height.

5. The method according to claim 4, characterised in that the substrate (100) is cut so as to have a film (101) having the same surface as the surface of the base of the pad.

6. The method according to claim 4, characterised in that the substrate (100) is cut so as to have a film (101) having a surface greater than the surface of the base of the pad.

7. The method according to any one of claims 4 to 6, characterised in that, between step b) and step c), the method comprises an additional step during which an intermediate metallisation layer (400) then an additional thermoelectric element (500) made of a fourth material having a conductivity type opposite to the conductivity type of the second material, are deposited on the thermoelectric element (200).

8. The method according to claim 6 or 7, characterised in that, during step b), several pads are deposited and in that the substrate (100) is cut so as to have a structure comprising a film (101) on which several pads are disposed.

9. The method according to any one of the preceding claims, characterised in that the second material is selected from Si, SiGe, Bi2Te3, Half-Heusler and Skutterudites.

10. The method according to any one of the preceding claims, characterised in that the first material is 316L steel, aluminium, titanium, a CuZr alloy, a ceramic or graphite.

11. A thermoelectric structure obtained by the method according to any one of the preceding claims, comprising a film (101), for example made of 316L steel, aluminium, titanium, CuZr alloy, ceramic or graphite, on which one or more thermoelectric elements (200) are disposed.

12. The thermoelectric structure according to the preceding claim, characterised in that a metallic bonding layer (300), for example made of Al, Ti, Cu, Au or Ni, is disposed between the film (101) and the thermoelectric element(s) (200).

13. The thermoelectric device comprising two thermoelectric structures according to claim 11 or 12, each structure comprising a film (101,111), for example made of 316L steel, aluminium, titanium, CuZr alloy, ceramic or graphite, and one or more thermoelectric elements (200, 201, 210, 211), a metallic bonding layer (300, 310), for example made of Al, Ti, Cu, Au or Ni, which can be disposed between the film (101, 111) and the thermoelectric element(s) (200, 201, 210, 211) of the two thermoelectric structures, the thermoelectric element(s) of one of the thermoelectric structures being of a first conductivity type and the thermoelectric element(s) of the other thermoelectric structure being of a second conductivity type opposite to the first conductivity type.