Device, apparatus and method for thermal treatment of a multilayer body of a thin-film solar module

Abstract

The invention relates to a device (102) for thermally treating a multilayer body (1), comprising an energy source (16, 7, 11) having at least one radiant heater for generating heating radiation (6, 8), the multilayer body (1), and an intermediate element (15, 5, 12) arranged between the energy source (16, 7, 11) and the multilayer body (1). According to a first alternative, the intermediate element (15, 5, 12) comprises a surface element (17) embodied in the form of a flexible film (18). According to a second alternative, the intermediate element (15, 5, 12) comprises a surface element (17) implemented in the form of a flexible membrane (18) or a rigid plate (19), wherein the surface element (17) has a surface (27) facing the energy source (16, 7, 11) and can be irradiated by heating radiation (6, 8), wherein the surface (27) facing the energy source (16, 7, 11) is mechanically supported by a supporting device (22, 23, 25, 26) in the direction towards the energy source (16, 7, 11).

Description

Technical Field

[0001] The invention belongs to the technical field of thin-film solar module production and relates to a device, an apparatus and a method for heat treatment of a multilayer body of a thin-film solar module. Background Art

[0002] Photovoltaic layer systems for the production of thin-film solar modules are well known to the person skilled in the art. The materials of the layers, in particular the semiconductor materials of the absorber layers for the photoelectric conversion, are selected so that the incident sunlight can be converted into electric current with satisfactory efficiency. Due to the physical properties and the technical disposal, absorber layers made of amorphous, microcrystalline or polycrystalline silicon, cadmium telluride (CdTe), gallium arsenide (GaAs), copper indium / gallium diselenide / disulphide / disulphide selenide (Cu(In,Ga)(S,Se)2), copper zinc tin sulphide selenide (CZTS from the chalcopyrite compound semiconductor family) and organic semiconductors are particularly suitable. The quinary semiconductor Cu(In,Ga)(S,Se)2, which belongs to the chalcopyrite compound semiconductor family, has acquired special significance in the industrial mass production of thin-film solar modules.

[0003] A possible method for producing an absorber layer made of Cu(In,Ga)(S,Se)2 consists of a two-stage process. Such a two-stage method is known, for example, from J. Palm et al., "CIS module pilot processing applying concurrent rapid selenization and sulfurization of large area thin film precursors", Solid Films, 431-432, pp. 414-522 (2003). In a first stage, the precursor is deposited and then heat treated in a second stage. As a result of the heat treatment (RTP = rapid thermal processing), crystal formation and phase transformation of the precursor occur to form the semiconductor layer.

[0004] Thermal treatment of coated substrates is accomplished, for example, in a sequential system in which the coated substrates are fed into a succession of different chambers arranged along a processing route. In a typical configuration, such a sequential system comprises a loading station, a heating chamber in which the coated substrates are heated, preferably at a heating rate of a few °C / s, and a cooling chamber in which the coated substrates are cooled and removed from the system.

[0005] Thermal treatment of coated substrates is a cost-intensive and technically demanding process that requires high temperatures, precise temperature ramps and defined process atmosphere compositions if high levels of efficiency with sufficiently good repeatability are to be achieved. Thus, for example, in the production of high-quality Cu(In,Ga)(S,Se)2 compound semiconductors, the vapor pressure and the amount of selenium (Se) in the process atmosphere must be well controlled. Sufficient Se is necessary to ensure complete selenization of the metal precursors. Significant Se losses will result in incomplete conversion of the precursors into compound semiconductors. Even small Se losses will still lead to recombination, i.e. loss of efficiency and increased transient effects (especially hygrothermal losses) in the finished thin-film solar module.

[0006] In order to better control the parameters of the heat treatment process, it is known to confine the processing space for the coated substrate by means of a process box. In this way, the partial pressure of the easily volatile chalcogen components (such as selenium or sulfur) can be kept as constant as possible during the heat treatment. In addition, the exposure of the process chamber to corrosive gases is reduced. Selenium and sulfur are extremely corrosive substances that strongly attack metals at the high temperatures required during the heat treatment.

[0007] The heating of the coated substrate is usually done by electrically operated radiant heaters, which are arranged on the lid and bottom sides in the process box, where the heating radiation (visible to infrared) is directed to the lid and bottom of the process box. Glass ceramic plates have proven themselves for the lid and bottom, as they are resistant to high temperatures, insensitive to temperature gradients, and inert to corrosion by selenium or sulfur, have a very low coefficient of expansion, and have high mechanical stability. The frame is usually made of graphite or a composite material, such as carbon fiber reinforced carbon (CFRC = carbon fiber reinforced carbon, RCC = reinforced carbon carbon, CFG = carbon fiber carbon composite).

[0008] Although the use of a process box allows reliable production of high-quality absorber layers, the energy consumption of this production process is relatively high, since not only the coated substrate but also the process box has to be heated. If 4 mm thick plates are used for the base and the cover in each case, their individual mass is in each case already four times the mass of the coated substrate. In the case of a substrate size of approximately 1 m2 (5 kg at a thickness of 2 mm), the total weight of the process box with the frame is approximately 40 kg. During the thermal conversion of the precursor to the processing temperature, this mass is heated and then has to be cooled again. This is disadvantageous, since for the sustainable and economical production of thin-film solar modules it is desirable to keep the energy consumption as low as possible.

[0009] Furthermore, the general requirements for the process box must be met, namely a rapid energy input into the interior, which enables a heating rate of the precursor of up to several ° C / s, and sufficient mechanical robustness to ensure the transport of the coated substrates (typically about 5 kg / m2) and to withstand a slight positive or negative pressure during rinsing and pumping processes and during convection cooling. The mechanical load is approximately up to 40 kg / m2 (excluding its own weight). In particular, this load requires that the materials used have a high bending strength. Furthermore, the process box must have sufficient mechanical rigidity so that the volume of the processing space does not change significantly, for example, during the thermal treatment of the coated substrates due to elastic or plastic deformations. Summary of the invention

[0010] The present invention is directed to the above-mentioned objectives and aims at advantageously improving the apparatus known from the prior art for the thermal treatment of coated substrates in such a way that energy-saving and economical production of thin-film solar modules with reproducible high efficiency levels can be reliably achieved.

[0011] These and other objects are achieved according to the proposal of the invention by a device, an apparatus and a method for the thermal treatment of a multilayer body having the features of the independent and equivalent claims. Preferred embodiments are evident from the dependent claims.

[0012] According to the invention, a device and an apparatus for heat treating a multilayer body are proposed.In the context of the invention, the expression "multilayer body" describes a substrate, for example a glass substrate, having one or more layers applied thereto, which layers are to be subjected to heat treatment.

[0013] The multilayer body is used to produce a thin-film solar module. It is preferably a thin-film solar module with a composite pane structure having a cover plate and a back plate (e.g. a glass plate) fixedly bonded to each other via a thermoplastic or cross-linked polymer intermediate layer (e.g. PVB or EVA). The invention particularly relates to a multilayer body for a thin-film solar module in a substrate configuration, in which the layer structure for producing solar cells is applied to the surface of the back substrate facing the light-incoming side, or in a cover plate configuration, in which the layer structure is applied to the surface of a transparent cover plate facing away from the light-incoming side.

[0014] According to customary usage, the term "thin-film solar module" refers to a module with a layer structure of low thickness (e.g. a few micrometers) which requires a carrier to obtain sufficient mechanical strength. The carrier can be made of glass, plastic, metal or metal alloy, for example, and can be designed as a rigid plate or a flexible film, depending on the respective layer thickness and the specific material properties.

[0015] In thin-film solar modules, the layer structure comprises in a manner known per se a back electrode layer, a front electrode layer, and a photovoltaically active absorber layer arranged between the back electrode layer and the front electrode layer. The front electrode layer is optically transparent, since it is necessary to allow light to pass through the layer structure. The front electrode layer comprises or generally consists of a doped metal oxide (TCO=transparent conductive oxide), for example n-conducting, in particular aluminum-doped, zinc oxide (AZO).

[0016] Preferably, the multilayer body has a layer stack (precursor) for producing a semiconductor material containing a chalcogen. Elements of the sixth main group of the periodic table are called chalcogens. The semiconductor material of the absorption layer contains at least one chalcogen, preferably sulfur and / or selenium. Particularly preferably, this is a chalcogen-containing chalcopyrite compound semiconductor, which is advantageously a ternary I-III-VI compound semiconductor from the copper indium disulphide / diselenide / gallium family, abbreviated to the chemical formula Cu(In,Ga)(S,Se)2. In the aforementioned chemical formula, indium and gallium can each exist alone or in combination. This also applies to the chalcogen elements sulfur and selenium, each of which can exist alone or in combination. Particularly suitable materials for the absorption layer are CISe (copper diselenide), CIS (copper disulfide), CIGSe (copper indium gallium diselenide), CIGS (copper indium gallium disulfide) or CIGSSe (copper indium gallium disulfide selenide). Likewise preferably, the multilayer body can have a layer stack (precursor) for producing a chalcogen-containing copper-tin-sulphide compound semiconductor, preferably copper-zinc-tin-selene sulfide (CZTS). The chalcogen-containing copper-tin-sulphide compound semiconductor contains at least one chalcogen, preferably sulfur and / or selenium.

[0017] In short, in a two-stage RTP process, a Cu(In,Ga)(S,Se)2 absorption layer is produced on a substrate. Here, after the back electrode layer is produced on the substrate, a precursor layer is first applied on the back electrode layer. The precursor layer, which may include one or more plate layers, contains the elements copper, indium and gallium, which are preferably applied by sputtering. The precursor layer further includes at least one chalcogen in elemental form, preferably selenium and / or sulfur, which is preferably applied by thermal evaporation. During these deposition processes, the temperature of the carrier is generally below 100°C, so that the elements remain as essentially unreacted metal alloys and chalcogens (selenium and / or sulfur). The precursor layer then reacts by heating in an atmosphere containing at least one chalcogen (selenium and / or sulfur) to form a Cu(In,Ga)(S,Se)2 compound semiconductor (thermal reaction). For example, the precursor layer contains only elemental selenium as a chalcogen, and the thermal conversion of the precursor layer is completed in an atmosphere containing only sulfur as a chalcogen. As a result of the thermal treatment of the precursor layer, crystal formation and phase change occur in the precursor layer to form a semiconductor layer (compound semiconductor). Similarly, a chalcogen-containing pyrocatechol compound semiconductor can be produced in a two-stage process, wherein a precursor layer comprising copper, zinc, tin and at least one chalcogen (preferably sulfur and / or selenium, particularly preferably only selenium) is first applied to the back electrode layer. The precursor layer is then reacted by heating in an atmosphere comprising at least one chalcogen (preferably sulfur and / or selenium, particularly preferably only sulfur) to form a compound semiconductor.

[0018] The device according to the invention for thermally treating a multilayer body comprises an energy source with at least one radiant heater for generating heating radiation (e.g., a radiator group with a one-dimensional or two-dimensional arrangement of the radiant heaters), the multilayer body, and an intermediate element arranged between the energy source and the multilayer body element, on which the heating radiation impinges. Preferably, the intermediate element is arranged in the immediate vicinity of the energy source. Thus, the heating radiation impinges directly on the intermediate element or at least one or more sections of the intermediate element. Preferably, the intermediate element is arranged in the immediate vicinity of the multilayer body, so that there is no physical object, such as a layer or a plate, between the intermediate layer and the multilayer body.

[0019] According to a first alternative, the intermediate element comprises a surface element implemented in the form of a flexible film. According to a second alternative, the intermediate element comprises a surface element implemented in the form of a flexible film or a rigid plate, wherein on the side of the surface element facing the energy source, a supporting device for mechanically supporting the surface element in the direction toward the energy source is arranged. Specifically, the surface of the surface element facing the energy source (which surface can be irradiated by the heating radiation of the energy source) is mechanically supported by the supporting device in the direction of the energy source. For example, the intermediate element consists only of the surface element or of the surface element and the supporting device. The intermediate element is arranged between the energy source and the multilayer body. Therefore, the supporting device is arranged on the side of the intermediate element facing away from the multilayer body.

[0020] In the context of the present invention, the term "surface element" refers to a flat, planar body, for example, having a rectangular shape. The surface element has a first surface facing the energy source, which surface can be directly irradiated by the heating radiation of the energy source. The surface directly irradiated by the heating radiation can be equal to the first surface of the surface element, but can also be smaller. Opposite the first surface, the surface element has a second surface facing away from the energy source, which can serve as a base and as a support surface for the multilayer body during use of the intermediate element.

[0021] In the device for heat treatment of a multilayer body according to the invention, the energy source and the intermediate element are arranged so that the multilayer body can be heated directly by the heating radiation (in the case where the surface element is transparent or partially transparent to the heating radiation), or indirectly by the heated surface element (in the case where the surface element is opaque to the heating radiation). In the case of direct heating, at least a portion of the heating radiation of the energy source passes through the surface element and impinges on the multilayer body, as a result of which the multilayer body is heated. In the case of indirect heating, the surface element is heated by the impinging heating radiation of the energy source and transfers heat to the multilayer body via thermal radiation and thermal conduction. If the surface element is opaque, the heating of the multilayer body is essentially accomplished indirectly by the heated surface element by means of thermal radiation and thermal conduction. The surface element preferably has a low reflectivity and a high emissivity, so that the radiation emitted by the radiator group is absorbed to the greatest extent possible.

[0022] In the context of the present invention, the term "transparent" or "transparent" means a transmittance to the heating radiation of at least 85%, in particular at least 90%, preferably at least 95%, in particular 100%. The term "opaque" or "opaque" means a transmittance to the heating radiation of less than 5%, in particular 0%. The term "partially transparent" or "partially transparent" means a transmittance to the heating radiation between opaque and transparent.

[0023] The surface element is embodied according to a first alternative as a flexible film or according to a second alternative as a flexible film or a thin rigid plate with mechanical support means. According to the invention, the intermediate element can be embodied such that it has a lower mass than the intermediate elements used in the prior art, advantageously achieving a significant saving in energy costs in the thermal treatment of the multilayer body. Since the surface element can be very thin, even non-transparent materials can be used for the surface element, since the desired high heating rates of several ° C per second can only be achieved with very thin surface elements.

[0024] Preferably, the surface element has such a (low) thickness that the shape factor resulting from the thickness / diagonal quotient of the surface element is less than 4 mm / 1 m, ie less than 4*10 -3 Here, rectangular surface elements are considered, the diagonal of the first surface of which faces the energy source. Preferably, the surface element has such a thickness that the shape factor is less than 5*10 -4 This applies in particular to surface elements with a transmittance of less than 20%, less than 5% or less than 1%, so that a fast heating rate of the multilayer body is achieved. The form factor can also be larger if the transmittance of the surface element is greater than 50% or even greater than 70%.

[0025] Preferably, the thickness of the surface element is less than 4 mm, more preferably less than 1 mm, even more preferably less than 0.5 mm.

[0026] Preferably, the total mass of the intermediate element is selected such that it is less than 400%, preferably less than 200%, more preferably less than 100%, even more preferably less than 50%, most preferably less than 10% of the mass of the multilayer body. This can lead to significant energy cost savings for the heat treatment of the multilayer body.

[0027] If the surface element is realized in the form of a non-dimensionwise stable, ie flexible, film, the film thickness is preferably less than 0.5 mm, more preferably less than 0.3 mm.

[0028] Preferably, the film comprises or is made of graphite, with or without a tear-resistant and corrosion-resistant inhibitor. Preferably, the film comprises or is made of a composite material, such as carbon fiber reinforced carbon. The film may also be a metal foil coated with an anticorrosion layer on one or both sides. Therefore, the coating of the metal foil is corrosion-resistant at high temperatures. An example of this is that both sides of a molybdenum foil are coated with, for example, a 20nm to 1000nm thick molybdenum nitride (MoN) layer, which serves as an anticorrosion layer. Other ceramic anticorrosion layers, such as those made of SiC, Al2O3, TiN, etc., may also be used. Metal foils are very mechanically stable in terms of bending strength and tear resistance. Therefore, they can be very thin. High thermal conductivity ensures uniform temperature distribution. Due to the coating or surface roughness of the metal foil, the emissivity of the metal foil should be as high as possible, and its reflectivity should be very low. Corrosion resistance is ensured by the anticorrosion layer.

[0029] As an alternative to coated metal foils, composite films are also suitable, for example metal foils bonded to a graphite foil on one or both sides by means of an adhesive (e.g. a ceramic adhesive or a graphite adhesive). The graphite foil assumes the functions of sealing and corrosion stability. The mechanical stability is achieved by the metal foil.

[0030] If the surface element is implemented in the form of a rigid plate, the thickness of the plate is preferably less than 4 mm, more preferably less than 1 mm, even more preferably less than 0.5 mm. Preferably, the plate comprises or consists of glass ceramic, carbon fiber reinforced carbon or a glass with a high softening point (generally above 800° C.), such as borosilicate glass, aluminosilicate glass or quartz glass.

[0031] The surface element, which is implemented in the form of a flexible film or a rigid plate, preferably has a low reflectivity and a high emissivity, so that the radiation emitted by the energy source is absorbed to the greatest extent possible. Preferably, the reflectivity of the surface element facing the energy source is less than 10%, more preferably less than 5%, and most preferably less than 2% (the percentage figures are based on the share of reflected heating radiation).

[0032] The second surface of the surface element implemented in the form of a flexible film or a rigid plate, which can be used as a support surface for the multilayer body, preferably has a raised pattern so that its contact area with the multilayer body is as small as possible. Thus, the influence of heat conduction is suppressed. If the multilayer body is raised during heating or is not completely planar due to preliminary processes, heat conduction can lead to very spatially non-uniform heating. Patterning can be accomplished by roughening, local decoating or coating. Patterning includes ridges that can be implemented as random and / or periodic patterns, the size (height) of the pattern perpendicular to the surface element preferably being in the range of one micrometer to several hundred micrometers.

[0033] The supporting device is implemented so that it mechanically supports the surface element or the first surface of the surface element in the direction toward the energy source (on the side of the intermediate element facing away from the multilayer body). For this purpose, the supporting device is arranged between the surface element and the energy source, wherein the energy source is arranged on the side of the surface element facing away from the multilayer body. The supporting device preferably does not support the surface element over its entire surface, in other words, the contact area of ​​the supporting device (where the supporting device is in touch contact with the first surface) is smaller than the first surface. In particular, the supporting device is therefore not implemented in the form of a layer or coating applied to the first surface of the surface element. Preferably, the supporting device extends over the entire (complete) surface element or the first surface, respectively, but does not completely cover the surface element or the first surface, respectively. In other words, although the supporting device extends over the entire first surface, the first surface has one or more parts that are not covered by the supporting device. Specifically, the supporting device supports the first surface in an inner part surrounded by the circumferential edge portion of the first surface. In particular, the supporting device supports the first surface in its central (middle) section.

[0034] Preferably, the support device covers less than 10% of the first surface of the surface element (in a vertical view through the surface element), so that the heating radiation impinging on the surface element is only slightly shielded by the support device. Thus, the multilayer body can be heated uniformly and only slight thermal inhomogeneities occur.

[0035] For example, the surface element and the supporting device are only in loose touch contact, wherein the supporting device is in contact with the first surface of the surface element. Preferably, the surface element and the supporting device are fixedly connected to each other. For example, the supporting device is fixedly connected to the first surface of the surface element, for example by an adhesive, preferably by a ceramic adhesive. Preferably, the supporting device is fixedly connected to the surface element only in some places, in particular at some points, to minimize undesired heat transfer (cold bridges).

[0036] The combination of the surface element and the supporting device decouples, so to speak, the requirements for the intermediate element, on the one hand, enabling the formation of a low-mass, gas-tight processing space, and on the other hand, achieving sufficient mechanical stability and adequate resistance to corrosive substances arising during heat treatment. In particular, the surface element can be selectively optimized with regard to the gas-tight formation of a low-mass and corrosion-resistant processing space, wherein sufficient mechanical stability is ensured by the supporting device.

[0037] According to a preferred embodiment of the invention, the support device is implemented in the form of a grid of intersecting linear support elements, which preferably extends over the complete (entire) surface element or the first surface of the surface element, respectively. The grid has one grid or preferably has a large number of grids. Advantageously, the linear support elements in the grid are fixedly connected to each other. According to another preferred embodiment, the linear support elements are arranged in a linear arrangement, which preferably extends over the complete (entire) surface element or the first surface of the surface element, respectively, wherein the linear support elements are arranged side by side, in particular in parallel. With the help of this support device, on the one hand, good mechanical support of the surface element can be achieved. On the other hand, due to the shielding of the heating radiation, the inhomogeneities during the heating of the multilayer body are relatively low. Advantageously, the grid or the linear arrangement extends over the entire first surface of the surface element (in a vertical view through the surface element), but is not in touch contact with the entire first surface.

[0038] Depending on the thickness of the linear support elements, their number can be appropriately selected depending on the absorption of the forces required for the mechanical support, wherein a smaller number of thicker support elements or a larger number of thinner support elements can be provided. The thinner the linear support elements, the smaller the possible shading and temperature inhomogeneities caused thereby. The surface element implemented in the form of a film or sheet can be bonded to the linear support elements, for example, by means of a ceramic adhesive.

[0039] Advantageously, the grid of linear support elements is a grid of wires or rods, wherein the linear support elements can be made of metal or another material. Optionally, the linear support elements are made of metal coated with an anti-corrosion layer. For example, the metal wires contain or are made of molybdenum or tungsten alloys. For example, the ceramic anti-corrosion layer contains or is made of Al2O3, MoN, Si3N4, etc. The (wire) grid can also be produced from glass fibers. For example, the linear support elements can be made of graphite, metal, ceramic, glass ceramic or glass with a high softening point (typically above 800° C.), such as borosilicate glass, aluminosilicate glass or quartz glass. They can also be made of composite materials such as carbon fiber reinforced carbon.

[0040] The linear support element is preferably embodied as a wire or a rod. According to the common usage of the terms, a rod differs from a wire only by its larger cross section.

[0041] The cross section of the linear support element is preferably circular (circle or disc) or rectangular. In the case of a rectangular linear support element (rod), the narrower surface is preferably parallel to the surface element (first surface). With the help of a rectangular cross section with the narrower side parallel to the surface element, high rigidity is achieved together with reduced shading. Depending on the material and construction, the cross section of the linear support element can be circular (round wire or round rod), ring (tube), T-shaped (T-beam), or double T-shaped (double T-beam).

[0042] The linear support element may be opaque, partially transparent or transparent. Preferably, the linear support element is at least partially transparent, i.e. partially transparent or transparent. Advantageously, the absorption of the heating radiation in the linear support element is less than 50%, more preferably less than 20%, most preferably less than 5%. Due to the transparency, the blocking of the heating radiation on the surface of the surface element (film or sheet) is very low.

[0043] Since, due to the relatively large mass, the linear support element heats up more slowly than the surface element itself and since, in particular, the opaque rods also cause a certain shading, it is advantageous to include a thermal insulator between the linear support element and the surface element. This prevents the connection point from acting as a heat sink. This could lead to inhomogeneities in the radiation group and therefore also in the multilayer body. This is advantageously a ceramic adhesive. The attachment is preferably done in point form to reduce cold bridges.

[0044] The invention further relates to an apparatus for the thermal treatment of a multilayer body, comprising at least one device for heating a multilayer body embodied as described above.

[0045] The device for heat treating a multilayer body comprises a device for forming a (reduced) processing space of the multilayer body. The processing space is reduced relative to the chamber volume of the chamber (heating chamber or cooling chamber), and the device for forming the reduced processing space is located in the chamber. The device for forming the processing space comprises a bottom side section referred to as the "bottom" hereinafter, a cover side section referred to as the "cover" hereinafter, and at least one frame, which together form a processing space for accommodating the multilayer body, which processing space is airtight at least during the heat treatment. The frame connects the bottom and the cover to each other and simultaneously serves as a spacer between the cover and the bottom. The frame is made of, for example, graphite or a composite material such as carbon fiber reinforced carbon.

[0046] In the context of the present invention, "gas-tightness" means that the processing space does not necessarily have to be closed. On the contrary, the processing space can even have one or more openings to the external environment, as long as the gas exchange between the processing space and the external environment during the heat treatment of the multilayer body is very low, so that the atmosphere in the processing space is not substantially influenced by this gas exchange. This applies to the standard pressure that is customarily present during the heat treatment. However, if positive or negative pressure is applied, the gas exchange is no longer negligible.

[0047] The multilayer body is or can be accommodated in the processing space. The cover and the bottom are each flat planar section of the device for forming the processing space, for example in a rectangle, which are arranged in the working position with their planes usually parallel to the horizontal plane. The frame is usually arranged circumferentially around the bottom or the cover. The frame walls are usually aligned perpendicular to the horizontal plane. Preferably, the multilayer body is mounted on the bottom.

[0048] The frame may be fixedly connected to the cover and then referred to as a "cover frame". In this case, the frame is not fixedly connected to the bottom. Alternatively, the frame may be fixedly connected to the bottom and then referred to as a "bottom frame". In this case, the frame is not fixedly connected to the cover. Alternatively, the device for forming a processing space may include two frames, wherein the first frame is fixedly connected to the cover (and not fixedly connected to the bottom) and is referred to as a "cover frame", and the second frame is fixedly connected to the bottom (and not fixedly connected to the cover) and is referred to as a "bottom frame". The bottom frame and the cover frame are not fixedly connected, or may be non-destructively detachably connected to each other. The bottom frame and the cover frame may be placed one on top of the other or embedded in each other to form a processing space.

[0049] The apparatus for heat treating a multilayer body further comprises a first or cover-side energy source having at least one radiant heater, which is arranged directly adjacent to the cover, and a second or bottom-side energy source having at least one radiant heater, which is arranged directly adjacent to the bottom. The device for forming a (reduced) processing space is located between the cover-side energy source and the bottom-side energy source. The cover-side energy source and the bottom-side energy source each comprise at least one radiant heater for generating heating radiation suitable for heating the multilayer body located in the processing space. Typically, the wavelength of the heating radiation is in the visible light spectrum (380nm to 780nm), and in the infrared wavelength spectrum above the visible light spectrum. At least one radiant heater can be linear or sheet-shaped. For example, in each case, the cover-side energy source and the bottom energy source are implemented in the form of a radiant heater group, wherein the arrangement of the radiant heaters is one-dimensional or two-dimensional.

[0050] In the device according to the invention for heat treatment of a multilayer body, the cover-side energy source, the cover as an intermediate element and the multilayer body form a first device according to the invention for heat treatment of a multilayer body. In addition or as an alternative, the bottom-side energy source, the bottom as an intermediate element and the multilayer body form a second device according to the invention for heat treatment of a multilayer body. In the case where the cover or the bottom is not part of the device according to the invention for heat treatment of a multilayer body, they are made of, for example, a glass ceramic plate.

[0051] The cover-side energy source and the cover are arranged so that the multilayer body located in the processing space can be heated directly by the heating radiation (in the case where the cover is transparent or partially transparent to the heating radiation) or indirectly by the heated cover (in the case where the cover is not transparent to the heating radiation). Therefore, the cover-side energy source is not located in the direct vicinity of the bottom. Correspondingly, the bottom-side energy source and the bottom are arranged so that the multilayer body located in the processing space can be heated directly by the heating radiation (in the case where the bottom is transparent or partially transparent to the heating radiation) or indirectly by the heated bottom (in the case where the bottom is not transparent to the heating radiation). Therefore, the bottom energy source is not located in the direct vicinity of the bottom.

[0052] As described above, in at least one device, the intermediate element can in particular have a surface element realized in the form of a flexible membrane. No supporting device is required here. Alternatively, the surface element can have a membrane or a rigid plate as the surface element, wherein a mechanical supporting device is additionally provided for supporting the surface element in the direction of the energy source.

[0053] According to a first variant of the device for heat treatment of a multilayer body, the means for forming the processing space comprises a single frame, which in this case is a cover frame fixedly connected to the cover. The cover comprises a surface element arranged between the cover-side energy source and the multilayer body located in the processing space, which is hereinafter referred to as the "cover surface element", and a support device for the cover surface element, which is hereinafter referred to as the "cover support device".

[0054] According to a second variant of the device for heat treatment of a multilayer body, the means for forming the processing space comprises a single frame, which in this case is a bottom frame fixedly connected to the bottom. The bottom comprises a surface element arranged between the bottom-side energy source and the multilayer body located in the processing space, which is hereinafter referred to as "bottom surface element", and a supporting device for the bottom surface element, which is hereinafter referred to as "bottom supporting device".

[0055] According to a third variant of the apparatus for heat treating a multilayer body, the device for forming a processing space includes a first frame and a second frame, wherein the first frame is a cover frame fixedly connected to the cover, and the second frame is a bottom frame fixedly connected to the bottom. Corresponding to the first variant, the cover includes a cover surface element and a cover support device. Corresponding to the second variant, the bottom includes a bottom surface element and a bottom support device. The cover frame and the bottom frame are not fixedly connected to each other, and can be non-destructively detachably connected to each other. In particular, the cover frame and the bottom frame can be placed one on top of the other or embedded in each other.

[0056] The cover surface element is opaque, partially transparent or transparent to the heating radiation of the cover side energy source. The bottom surface element is opaque, partially transparent or transparent to the heating radiation of the bottom side energy source.

[0057] The cover surface element and the bottom surface element are planar bodies in each case, which are rectangular, for example, when viewed from above toward the plane. The cover surface element forms a cover plane and serves to seal the processing space. It has an outer cover surface facing the energy source on the cover side and an inner cover surface facing the processing space. The bottom surface element forms a bottom plane and also serves to seal the processing space. It has an outer bottom surface facing the bottom side energy source and an inner bottom surface facing the processing space. Advantageously, the multilayer body resides on the inner bottom surface. Preferably, the bottom surface element or the inner bottom surface has a convex pattern so that the contact area with the multilayer body is as small as possible. Therefore, the influence of heat conduction is suppressed. If the multilayer body is convex during heating, or is not completely flat due to the preliminary process, heat conduction can cause very uneven heating in space. Patterning can be accomplished by roughening or coating, wherein the pattern is in the range of one micron to several hundred microns.

[0058] The cover support device is implemented so that it mechanically supports the cover surface element in the direction toward the cover side energy source. For this purpose, the cover is arranged between the cover surface element and the cover side energy source. Preferably, the cover support device is arranged on the outer cover surface, advantageously in contact with the outer cover surface. Advantageously, the cover support device is not located in the processing space. The cover support device does not support the cover surface element on its entire surface. On the contrary, the cover support device only supports the cover surface element in the region, that is, only in one or more regions of the cover surface element. Therefore, the entire surface of the cover surface element is not supported. Preferably, the cover support device covers less than 10%, more preferably less than 5%, and preferably less than 2% (in a vertical view through the cover surface element) of the outer cover surface, so that due to the cover support device, the heating radiation impinging on the cover surface element is only slightly blocked. Similarly, the bottom support device is implemented so that it mechanically supports the bottom surface element in the direction toward the bottom side energy source. For this purpose, the bottom support device is arranged between the bottom surface element and the bottom side energy source. Preferably, the bottom support device is arranged on the outer bottom surface, advantageously in contact with the outer bottom surface. Advantageously, the bottom supporting device is not located in the processing space. Furthermore, the bottom supporting device does not support the bottom surface element over its entire surface, but only in regions, i.e. only in one or more regions of the bottom surface element. Preferably, the bottom supporting device covers less than 10%, more preferably less than 5%, and best still less than 2% of the outer bottom surface (in a vertical view through the bottom surface element), so that due to the bottom supporting device, the heating radiation impinging on the bottom surface element is only slightly impaired.

[0059] Designing the cover and / or the bottom of the device for forming a (reduced) processing space as an intermediate element of the arrangement for heat treatment of a multilayer body according to the invention advantageously achieves a reduction in the total mass of the device for forming a processing space by reducing the mass of the intermediate element, without compromising its mechanical stability. Since, as a result, less mass of the device for forming the processing space is also heated (or cooled) during the heat treatment of the multilayer body located in the processing space, energy costs can be saved to a significant extent. Since the intermediate element is not supported over its entire surface by the associated supporting device, but only in some areas, the unobstructed path of the heating radiation to the surface element is only slightly affected, so that the multilayer body can be heated uniformly over its entire surface and only slight thermal inhomogeneities occur. In terms of the airtight embodiment of the processing space, the surface element (cover or bottom) can be selectively optimized to have low mass and corrosion resistance, while ensuring sufficient mechanical stability by the supporting device.

[0060] In the case of an embodiment as a thin rigid plate, the surface element can in particular have a thickness measured perpendicularly to the surface plane which, without mechanical support means, due to its own weight (cover) or due to its own weight plus the weight of the multilayer body and possibly the weight of the cover and frame (base), is likely to break or at least deflect perpendicularly to the surface plane which is no longer acceptable according to high quality requirements (elastic deflection of more than 2 mm per square meter). With support means, the deflection of the surface element is preferably less than 1 mm.

[0061] The present invention further extends to a method for heat treating a multilayer body, comprising:

[0062] Providing a multilayer body in an apparatus for heat treatment of a multilayer body as described above,

[0063] The multilayer body is irradiated with heating radiation directed towards the cover and the bottom.

[0064] With regard to the exemplary embodiments of a device for thermally treating a multilayer body for carrying out the method according to the invention, reference is made to the statements above.

[0065] Furthermore, the invention extends to the use of the method according to the invention for the thermal treatment of a multilayer body for producing absorbers during the production of thin-film solar cells.

[0066] The various embodiments of the invention can be implemented alone or in any combination. In particular, the features mentioned above and to be explained below can be used not only in the indicated combination but also in other combinations or alone, without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 is a cross-sectional view of an apparatus for heat treating a multilayer body, which is used to illustrate thermal relations during heating of the multilayer body;

[0068] Figure 2 yes Figure 1 A cross-sectional view of an apparatus for heat treating a multilayer body;

[0069] Figure 3 is a schematic diagram of a device consisting of an energy source, an intermediate element and a multilayer body;

[0070] Figure 4 is an exemplary embodiment of an intermediate element in cross-section;

[0071] Figure 5 It is in the plan view Figure 4 The intermediate element;

[0072] Figure 6 is another exemplary embodiment of an intermediate element in cross-section;

[0073] Figure 7 It is in the plan view Figure 6 The intermediate element;

[0074] Figure 8 is another exemplary embodiment of an intermediate element in cross-section;

[0075] Fig. 9 yes Figure 8 Another cross-sectional view of the intermediate element;

[0076] Fig.10 It is in the plan view Figure 8 The intermediate element;

[0077] Fig.11 It is in the plan view Figure 8 Variations of intermediate elements;

[0078] Fig.12 It has additives Fig. 9 A cross-sectional view of

[0079] Fig.13 is a flow chart for illustrating the steps of the method according to the invention for heat treating a multilayer body.

[0080] 1. Multilayer body; 2. Substrate; 3. Back electrode layer; 4. Precursor layer; 5. Bottom; 6. Lower heating radiation; 7. Bottom radiator group; 8. Upper heating radiation; 9. Thermal radiation; 10. Thermal conduction; 11. Cover radiator group; 12. Cover; 13. Frame; 14. Processing space; 15. Intermediate element; 16. Energy source; 17. Surface element; 18. Film; 19. Plate; 20. Wire; 21. Connection point; 22. Support device; 23. Wire grid; 24. Rod; 25. Rod grid; 26. Linear arrangement; 27. First surface; 28. Second surface; 29. ​​Outer cover surface; 30. Inner cover surface; 31. Outer bottom surface; 32. Inner bottom surface; 100. Device for thermally treating a multilayer body 1; 101. Device for forming a processing space 14; 102. Device for thermally treating a multilayer body 1. DETAILED DESCRIPTION

[0081] First consider Figure 1 and Figure 2 , in which a device according to the invention for thermally treating a multilayer body 1 , referenced as a whole by the reference numeral 100 , is schematically shown with reference to a cross-sectional view (section perpendicular to the substrate surface). Figure 1 depicts the basic heating operations during the heat treatment of the multilayer body 1; Figure 2 The structure of the multilayer body 1 during the heat treatment is depicted.

[0082] The apparatus 100 for heat treating a multilayer body 1 comprises a device, which is referenced as a whole by the reference numeral 101, for forming a (reduced) processing space. The device 101 comprises a bottom 5, a cover 12 and a frame 13, which spatially connects the bottom 5 and the cover 12 to each other and at the same time serves as a spacer for the bottom 5 and the cover 12. The bottom 5, the cover 12 and the frame 13 together form a gastight processing space 14 (see Figure 2 ), in which the multilayer body 1 can be heat treated. The multilayer body 1 resides here, for example, on a bottom 5.

[0083] The multilayer body 1 comprises a substrate 2, such as a glass plate, and a back electrode layer 3, such as made of molybdenum, applied on the substrate 2, and a precursor layer 4 applied thereon, which is thermally converted to form a compound semiconductor. In order to produce a Cu(In,Ga)(S,Se)2 absorption layer, the precursor layer 4 is made of various individual layers containing copper, indium and gallium, for example, which are applied by sputtering. The precursor layer 4 further contains at least one chalcogen in elemental form, preferably selenium and / or sulfur, which is preferably applied by thermal evaporation. The precursor layer 4 is reacted (thermally converted) to a Cu(In,Ga)(S,Se)2 compound semiconductor by heating in an atmosphere containing at least one chalcogen (selenium and / or sulfur). For example, the precursor layer 4 contains only elemental selenium as a chalcogen, and the thermal conversion of the precursor layer is performed in an atmosphere containing only sulfur as a chalcogen. The thermal conversion of the precursor layer 4 is performed in a processing space 14.

[0084] The cover radiator group 11 adjoining and directly adjacent to the cover 12 has a plurality of radiant heaters (e.g. halogen lamps, infrared radiators or surface radiators) placed in a one-dimensional or two-dimensional arrangement (array) as cover-side energy sources for emitting heating radiation for the cover-side heating of the multilayer body 1. Similarly, the bottom radiator group 7 adjoining and directly adjacent to the bottom 5 has a plurality of radiant heaters (e.g. halogen lamps, infrared radiators or surface radiators) placed in a one-dimensional or two-dimensional arrangement (array) as bottom-side energy sources for emitting heating radiation for the bottom-side heating of the multilayer body 1. The device 101 for forming the processing space 14 is located between the bottom radiator group 7 and the cover radiator group 11. In general, both the bottom 5 and the cover 12 can in each case be regarded as intermediate elements located between the energy source 16 (bottom radiator group 7 or cover radiator group 11) and the multilayer body 1. The cover 12 has an outer cover surface 29 facing the cover radiator group 11 and, in contrast, an inner cover surface 30 facing the multilayer body 1. The bottom 5 has an outer bottom surface 31 facing the bottom radiator group 7 and, opposite thereto, an inner bottom surface 32 facing the multilayer body 1. The multilayer body 1 preferably rests on the inner bottom surface 32.

[0085] like Figure 1As shown, the radiant heaters of the cover radiator group 11 emit upper heating radiation 8, which impinges on the outer cover surface 29, partially passes through the (here, for example, partially transparent) cover 12, and impinges on the upper side of the multilayer body 1, namely on the precursor layer 4. The multilayer body 1 is in the region of the upper heating radiation 8. Part of the upper heating radiation 8 is absorbed by 12 and heats the cover 12, which in turn emits thermal radiation 9, which likewise heats the multilayer body 1. The radiant heaters of the bottom radiator group 7 emit lower heating radiation 6, which impinges on the (here, for example, partially transparent) outer bottom surface 31 of the bottom 5 and heats the bottom 5. The bottom 5 transfers energy to the multilayer body 1 by thermal conduction 10 and thermal radiation. Although the multilayer body 1 is heated primarily from above by the upper heating radiation 8, it is also heated from below by thermal conduction 10 and thermal radiation of the heated bottom 5.

[0086] After the multilayer body 1 has been placed on the bottom 5, the processing space 14 is filled with process gas and closed. Then, the temperature is controlled at a rate of a few degrees Celsius per second, for example 5 degrees Celsius per second, wherein the cover radiator group 11 and the bottom radiator group 7 can also be controlled individually to generate a specified heating output. Due to the simultaneous heating of the cover 12 and the bottom 5, condensation of volatile components in the atmosphere of the processing space 14 can be prevented at least to a large extent.

[0087] Figure 3 A schematic diagram of an arrangement consisting of an energy source 16 (such as a bottom radiator group 7 or a cover radiator group 11), an intermediate element 15 (such as a bottom 5 or a cover 12) and a multilayer body 1 is depicted, which is also shown in FIG. Figure 1 and Figure 2 The intermediate element has a first surface 27 facing the energy source 16 and a second surface 28 facing away from the energy source 16 . The heating radiation of the energy source 16 impinges on the surface 27 .

[0088] The heating energy necessary to heat the multilayer body 1 to the desired temperature without the intermediate element 15 represents the minimum energy consumption E0. The main source of losses when heating the multilayer body 1 is the energy Ez=ΔQ, which is necessary to heat the intermediate element 15, which is given by the following formula:

[0089] Ez=ΔQ=c*M*ΔT

[0090] M is the mass, c is the heat capacity and ΔT is the desired heating of the intermediate element 15 .

[0091] The greater the mass M and the heat capacity c of the intermediate element 15, the higher the energy loss Ez. The reduction in mass M offsets the mechanical load capacity. The required size (e.g. 1-2 m 2) would bend excessively or already break due to its own weight or due to the weight of the substrate + bottom + cover + frame and the additional mechanical loads during transportation and due to the pressure difference. Therefore, simply reducing the thickness of the glass-ceramic intermediate element 15 is excluded.

[0092] If a stationary process hood is constantly in the radiation field of the radiant heater, it is not subject to such large temperature fluctuations as a transportable process box. A stationary process hood would then have little chance of cooling down during the heating process and, regardless of its quality, would reach a temperature during stationary operation which results from the balance between the energy input due to the radiation of the radiant heater and the energy losses due to radiation, heat conduction and convection. If a stationary process hood is used during heater-assisted cooling, it would also cool down significantly and be reheated with the next multilayer body. In contrast, a transportable process box has almost room temperature and must be reheated with the thermal treatment of the multilayer body and cooled down again to approximately room temperature.

[0093] It is conceivable to use an intermediate element 15 with the greatest possible transparency, so that the absorption of the heating power is very low. The above formula can be rewritten for this purpose:

[0094] r=ΔT / Δt=Pabs / (c*M)

[0095] Here, r is the heating rate and Pabs is the absorbed heating radiation. This equation can be used for both the intermediate element 15 and the multilayer body 1. Therefore, the heating rate r increases with decreasing mass M and heat capacity c. If, however, the absorbed radiation energy Pabs is very low due to very low absorption, the multilayer body 1 can be heated by the transparent intermediate element 15, which also does not heat to the same extent. In continuous operation, the energy losses caused by heating the intermediate element 15 are a function of the absorption of the intermediate element 15, the average heating power and the cycle time, since each new substrate (multilayer body 1) contributes again to the cooling of the intermediate element 15 via thermal radiation and heat conduction. In the case of a mobile process box, there is also active cooling at the end of the process cycle.

[0096] Of course, there are glass ceramics with higher transparency; however, it has been shown that the absorption is still so high that the glass ceramic is heated together with the mobile process box to almost the substrate temperature during the entire process cycle. Quartz of the required size is very expensive, if it is available at all. In addition, if the temperature of the intermediate element 15 is significantly lower than that of the substrate, selenium or other gaseous compounds with a lower melting point can condense there at least temporarily. This leads to temporary chalcogen mass losses in critical process stages. With increasing condensation, the absorption of the heating radiation in the condensate will increase. A steady state will be established.

[0097] Here, the invention takes a different approach by significantly reducing the mass of the intermediate element 15 through an improved design and suitable thinner materials. Due to the much lower mass of the intermediate element 15, even opaque materials can be used for this. Only by using very thin intermediate elements 15 can the desired rapid heating rates of typically 1 to 5°C / s be achieved. In particular, the tasks of gas-tight and corrosion-resistant sealing of the process space and the task of mechanical stabilization caused by the intermediate element 15 can be separated and individually optimized by using a combination of flat surface elements and associated support devices.

[0098] This will be explained in detail below. Figure 4 and Figure 5 This is shown with reference to the novel intermediate element 15, which may serve as the cover 12 and / or the bottom 5 of the device 100 for Figure 1 and Figure 2 Heat treatment of the multilayer body 1.

[0099] The intermediate element 15 is therefore a surface element 17 which is embodied here, for example, in the form of a flexible membrane 18 . Figure 4 A cross-sectional view (perpendicular to the plane of the surface element 17) is depicted; Figure 5 A plan view is depicted. The membrane 18 is stretched within the frame 13, wherein the inner area of ​​the frame 13 is completely covered by the membrane 18. The membrane 18 is fixedly connected to the frame 13. The thickness of the membrane 18 is less than 0.5 mm, preferably less than 0.3 mm. The tensioning of the membrane 18 must be strong enough to withstand the mechanical loads. This applies in particular to the case where an intermediate element 15 is used as the bottom 5, on which the weight of the multilayer body 1 and possibly also the weight of the frame 13 and the cover 12 reside. Due to pressure differences (during the pumping / flushing cycle) and convection cooling, pressures of up to 40 kg / m 2 load. Materials for membrane 18 include, for example, graphite or composite materials, such as carbon fiber reinforced carbon, with or without corrosion inhibitors. Alternatively, a metal foil coated with an anti-corrosion layer on one or both sides can be used. Another alternative is a composite membrane in which a metal foil is bonded to one or both sides of a graphite film by means of a ceramic or graphite adhesive. Metal foils have extremely high mechanical stability in terms of bending strength and tear resistance, so that they can be very thin. High thermal conductivity ensures a uniform temperature distribution. Graphite films provide corrosion stability. The foil preferably has low reflectivity and high emissivity so that the radiation emitted from the radiator group is absorbed as much as possible.

[0100] When the film forms the bottom 5, the film is preferably patterned with ridges so that the contact area with the multilayer body 1 is as small as possible. Thus, the influence of heat conduction is suppressed.

[0101] when Figure 1 and Figure 2 The cover 12 and the bottom 5 of the apparatus 100 for heat treating a multilayer body 1 are both Figure 4 and Figure 5 In the embodiment of the intermediate element 15 depicted in FIG. 1 , there are two frames 13 which can be placed on top of or inside each other and connected to each other non-fixedly or non-destructively detachably.

[0102] Figure 6 Another exemplary embodiment of the intermediate element 15 is shown using a cross-sectional view. The intermediate element 15 is Figure 4 and Figure 5 A further development of the intermediate element 15. Figure 7 A plan view of the intermediate element 15 is depicted. In order to avoid unnecessary repetition, only the components with respect to Figure 4 and Figure 5 The differences to the exemplary embodiments of the present invention are noted and, in other respects, reference is made to the above statements.

[0103] Therefore, the intermediate element 15 includes a surface element 17 implemented as a flexible membrane 18 or a rigid plate 19. Similar to the flexible membrane 18, the rigid plate 19 extends over the entire inner area of ​​the frame 13. The intermediate element 15 further includes a supporting device 22, which is implemented here as a wire grid 23, for example. The wire grid 23 is composed of a plurality of straight wires 20 that intersect and are connected to each other. The intersecting wires 20 form a plurality of polygonal grids. The wire grid 20 extends over the entire surface of the surface element 17 within the frame 13 (i.e., the first surface 27). As shown in Figure 6 , the wire grid 23 is fixedly connected to the surface element 17 at the connection point 21. For the fixed connection of the intermediate element 15 to the frame 13, the surface element 17 is fixedly connected to the frame 13 (e.g. clamped), wherein the support device 22 is not directly fixedly connected to the frame 13. Alternatively, the support device 22 can be fixedly connected to the frame 13, while the surface element 17 is not fixedly connected to the frame 13. The surface element 17 is then clamped or fastened onto the support device 22. In a further alternative, both the surface element 17 and the support device 22 can be fixedly connected to the frame 13 directly in each case.

[0104] The supporting device 22 is arranged on the side of the surface element 17 facing the energy source 16, here, for example, in touching contact with the first surface 27 of the surface element 17. The supporting device 22 supports the surface element 17 flatly in the direction of the energy source 16 and ensures sufficient mechanical stability of the surface element 17.

[0105] The connection points 21 are made of, for example, an adhesive with low thermal conductivity, such as a ceramic adhesive. Since the connection points 21 fasten the surface element 17 to the wire 20, the surface element 17 does not necessarily have to be clamped in the frame 13, since the mechanical load is borne by the wire 20. Figure 4 and Figure 5 Compared to the exemplary embodiment of the invention in which the surface element 17 is not supported by the mechanical support device 22, the mechanical loads are absorbed by the threads 20, which can have higher mechanical loads in terms of weight and the bending forces that occur. The membrane 18 or sheet 19 must be attached to the frame 13 so that the processing space is sufficiently airtight.

[0106] The surface element 17 can be implemented as a rigid plate 19 with a low thickness. For example, composite materials such as carbon fiber reinforced carbon, glass ceramics, or glasses with a high softening point such as borosilicate glass, aluminosilicate glass or quartz glass can be used as materials. The plate 19 is thin and its thickness is preferably less than 4 mm, more preferably less than 1 mm, even more preferably less than 0.3 mm.

[0107] The wire 20 is made of a metal such as molybdenum or a tungsten alloy. The wire 20 may be additionally coated with an anti-corrosion layer made of, for example, Al2O3, MoN, Si3N4 or the like.

[0108] If the thermal conductivity of the film 18 or the sheet 19 is good, the shading caused by the wires 20 has hardly any effect on the radiation to the multilayer body 1. In this embodiment, the mass of the intermediate element 15 can be very low. Due to the use of composite technology, the requirements and functions are divided between the two components: the film 18 or the sheet 19 bears the main load of corrosion resistance and sealing; the wire grid 23 bears the mechanical requirements in terms of tensile strength and bending strength.

[0109] Now consider Figures 8 to 11 , in which another exemplary embodiment of an intermediate element 15 is shown. Figure 8 A cross-sectional view (perpendicular to the surface element 17) is depicted; Fig. 9 A cross-sectional view (perpendicular to the surface element 17, but perpendicular to Figure 8 ); Fig.10 Depicted the floor plan; Fig.11 To avoid unnecessary repetition, only the Figure 6 and Figure 7 The differences to the exemplary embodiments of the present invention are noted and, in other respects, reference is made to the above statements.

[0110] The intermediate element 15 therefore comprises a supporting device 22 which is not formed here by a wire 20 but by a rod 24. Fig.10As depicted in the plan view of FIG. , the rods 24 may be arranged in the form of a rod grid 25 having intersecting rods 24, similar to the wire grid 23. The rod grid 25 has a plurality of polygonal meshes. Fig.11 In the alternative embodiment depicted in FIG. 1 , the rods 24 are arranged in a linear arrangement 26, wherein the rods 24 are arranged parallel and side by side. The rod grid 25 or the linear arrangement 26 extends over the entire surface of the surface element 17 within the frame 13, i.e. the first surface 27. Fig. 9 It can be seen in FIG. 2 that the rod 24 is fixedly connected to the surface element 17 at a connection point 21 in each case.

[0111] The rod 24 is made of, for example, graphite, metal, ceramic or glass ceramic. Preferably, the rod 24 has a rectangular cross section. With the aid of a rectangular cross section with a short side parallel to the surface element 17, high rigidity can be achieved together with reduced shielding. Depending on the material and the construction, the cross section of the rod 24 can also advantageously be circular (round rod), annular (tube), T-shaped (T-beam) or double T-shaped (double T-beam). The rod 24 is advantageously made of a partially transparent, more preferably transparent material. Preferably, the absorption of the heating radiation in the rod 24 is less than 20%, preferably less than 10%, and even more preferably less than 5%. Due to the transparency, the shielding of the heating radiation on the surface element 17 is very low. During this process, the rod 24 will be heated via the heating radiation and heat conduction. However, depending on the construction, there may be a permanent temperature gradient between the surface element 17 and the rod 24.

[0112] Fig.12 Shows relative to Fig. 9 Energy source 16 with additives. It can be seen that only very slight disturbances of the heating radiation 6, 8 occur due to the transparent rod 24. The heating beam A, which strikes perpendicularly to the surface of the surface element 17 (i.e. the first surface 27), passes the rod 24 from the side. Likewise, the heating beam C, which strikes perpendicularly to the surface of the surface element 17, can in most cases pass the transparent rod 24. The heating beam B, which passes obliquely through the rod 24, can also impinge on the surface of the surface element 17.

[0113] When using rods 24, it is advantageous to add an insulator between the rods 24 and the surface element 17. This can advantageously be a ceramic adhesive. Fastening can also be done in the form of points to reduce cold bridges. If the thermal conductivity of the surface element 17 is high, but the thermal conductivity of the connecting material is low, the effect of delayed heating can be minimized. The surface element 17 can be significantly stiffened by the rods 24 pointing perpendicular to the plane of the surface element 17. Therefore, the mechanical requirements on the surface element 17 can be reduced, so that the self-supporting surface between the rods 24 is significantly reduced. The spacing and cross-section of the rods 24 should be optimized so that the bending strength of the surface element 17 is sufficient to withstand the compressive load on the self-supporting surface between two rods 24. The number, spacing and overall size of the cross-section of the rods 24 should be selected only as necessary. Of course, the optimization of the mass and stiffness of the rods 24 perpendicular to the surface element 17 is much better than using only flat plates. The surface element 17 with a bar grid 25 or a linear arrangement 26 of rods 24 forms a composite with significantly higher stiffness and lower mass.

[0114] Fig.13 A method for heat treatment of a multilayer body 1 is shown. The method comprises a first step S1, in which the multilayer body 1 is arranged in an apparatus 100 according to the invention for heat treatment of a multilayer body 1, and a second step S2, in which the multilayer body 1 is irradiated with heating radiation on the bottom side and the cover side. The respective heating radiation impinges on the cover and the bottom of the device for forming a (reduced) processing space.

[0115] The invention provides an improved device, apparatus and method for heat treating a multilayer body, wherein the mass of at least one of the intermediate elements can be significantly reduced. The intermediate element either has a surface element implemented in the form of a flexible film or has a surface element implemented in the form of a flexible film or a thin rigid plate and mechanically supported by a supporting device. Due to the reduced mass, the cost of heat treating the multilayer body can be saved without affecting the mechanical stability and corrosion resistance of the intermediate element.

Claims

1. A device (102) for heat treating a multilayer body (1), comprising: A bottom (5), a cover (12) and at least one frame (13), wherein the bottom (5), the cover (12) and the at least one frame (13) together form a processing space (14) for accommodating the multilayer body (1), the bottom (5) and the cover (12) being intermediate elements located between the energy source (16) and the multilayer body (1); The device comprises an energy source (16, 7, 11) of at least one radiant heater for generating heating radiation (6, 8), a multilayer body (1), an intermediate element (15, 5, 12) arranged between the energy source (16, 7, 11) and the multilayer body (1), the intermediate element being a surface element (17) embodied in the form of a flexible film (18); The flexible film (18) has the following features a), b) or c): a) the flexible membrane (18) is graphite or carbon fiber reinforced carbon, b) the flexible film (18) is a metal foil coated with an anti-corrosion layer on one or both sides, c) The flexible film (18) is a composite film in which a metal foil is bonded to one or both sides of a graphite film by an adhesive.

2. A device (102) for heat treating a multilayer body (1), comprising: A bottom (5), a cover (12) and at least one frame (13), wherein the bottom (5), the cover (12) and the at least one frame (13) together form a processing space (14) for accommodating the multilayer body (1), the bottom (5) and the cover (12) being intermediate elements located between the energy source (16) and the multilayer body (1); The device comprises an energy source (16, 7, 11) of at least one radiant heater for generating heating radiation (6, 8), a multilayer body (1), an intermediate element (15, 5, 12) arranged between the energy source (16, 7, 11) and the multilayer body (1), the intermediate element comprising a surface element (17) embodied in the form of a flexible film (18) or a rigid plate (19), wherein the surface element (17) has a surface (27) facing the energy source (16, 7, 11), the surface element being capable of being irradiated by the heating radiation (6, 8), wherein the surface (27) facing the energy source (16, 7, 11) is mechanically supported in the direction towards the energy source (16, 7, 11) by a supporting device (22); The flexible film (18) has the following features a), b) or c): a) the flexible membrane (18) is graphite or carbon fiber reinforced carbon, b) the flexible film (18) is a metal foil coated with an anti-corrosion layer on one or both sides, c) The flexible film (18) is a composite film in which a metal foil is bonded to one or both sides of a graphite film by an adhesive.

3. The device (102) for heat treating a multilayer body (1) according to claim 2, wherein the rigid plate (19) is glass ceramic, carbon fiber reinforced carbon or glass with a softening point higher than 800°C.

4. The device (102) for heat treating a multilayer body (1) according to claim 3, wherein the glass having a softening point higher than 800°C is borosilicate glass, aluminosilicate glass or quartz glass.

5. The device (102) for thermally treating a multilayer body (1) according to any one of claims 1 to 3, wherein the thickness of the surface element (17) is less than 4 mm.

6. The device (102) for thermally treating a multilayer body (1) according to any one of claims 1 to 3, wherein the thickness of the surface element (17) is less than 1 mm.

7. The device (102) for thermally treating a multilayer body (1) according to any one of claims 1 to 3, wherein the thickness of the surface element (17) is less than 0.3 mm.

8. The device (102) for the thermal treatment of a multilayer body (1) according to claim 5, wherein the reflectivity of the surface element (17) to the heating radiation (6, 8) is less than 10%.

9. The device (102) for the thermal treatment of a multilayer body (1) according to claim 5, wherein the reflectivity of the surface element (17) to the heating radiation (6, 8) is less than 5%.

10. The device (102) for the thermal treatment of a multilayer body (1) according to claim 5, wherein the reflectivity of the surface element (17) to the heating radiation (6, 8) is less than 2%.

11. The device (102) for thermally treating a multilayer body according to claim 8, wherein the surface elements (17) have a relief pattern having a height of a few micrometers to several hundred micrometers measured vertically around the surface elements (17).

12. An apparatus (102) for heat treating a multilayer body (1) according to claim 2, wherein the support device (22) is implemented in the form of a grid (23, 25) of intersecting linear support elements (20, 24) or a linear arrangement (26) of side-by-side linear support elements (20, 24).

13. The device (102) for heat treating a multilayer body according to claim 12, wherein the linear support element (20, 24) is metal, graphite, ceramic, glass ceramic, glass with a softening point above 800°C or carbon fiber reinforced carbon.

14. The device (102) for heat treating a multilayer body according to claim 13, wherein the metal is a metal coated with an anti-corrosion layer.

15. The device (102) for heat treating a multilayer body according to claim 13, wherein the glass having a softening point higher than 800°C is borosilicate glass, aluminosilicate glass or quartz glass.

16. The device (102) for thermally treating a multilayer body (1) according to claim 12, wherein the linear support elements (20, 24) occupy less than 10% of the surface (27) of the surface element (17) facing the energy source (16, 7, 11).

17. The device (102) for thermally treating a multilayer body (1) according to claim 12, wherein the linear support elements (20, 24) occupy less than 5% of the surface (27) of the surface element (17) facing the energy source (16, 7, 11).

18. The device (102) for thermally treating a multilayer body (1) according to claim 12, wherein the linear support elements (20, 24) occupy less than 2% of the surface (27) of the surface element (17) facing the energy source (16, 7, 11).

19. The device (102) for the thermal treatment of a multilayer body (1) according to claim 13 or 16, wherein the linear support elements (20, 24) are at least partially transparent to the heating radiation (6, 8).

20. The device (102) for heat treating a multilayer body (1) according to claim 1, comprising: - a cover-side energy source arranged adjacent to the cover (12), - a bottom-side energy source arranged adjacent to the bottom (5), The cover side energy source, the cover (12) and the multilayer body (1) form a first device for thermally treating the multilayer body (1), and the bottom side energy source, the bottom (5) and the multilayer body (1) form a second device for thermally treating the multilayer body (1).

21. The device (102) for thermally treating a multilayer body (1) according to claim 20, wherein in at least one device (102) for thermally treating a multilayer body (1), the surface element (17) is fixedly connected to the frame (13).

22. The device (102) for thermally treating a multilayer body (1) according to claim 20, wherein in the first device for thermally treating a multilayer body (1), the surface element (17) is fixedly connected to a first frame; and in the second device for thermally treating a multilayer body (1), the surface element (17) is fixedly connected to a second frame, wherein the two frames (13) are not fixedly connected to each other.

23. The device (102) for heat treating a multilayer body (1) according to claim 2, comprising: - a cover-side energy source arranged adjacent to the cover (12), - a bottom-side energy source arranged adjacent to the bottom (5), The cover side energy source, the cover (12) and the multilayer body (1) form a first device for thermally treating the multilayer body (1), and the bottom side energy source, the bottom (5) and the multilayer body (1) form a second device for thermally treating the multilayer body (1).

24. An apparatus (102) for heat treatment of a multilayer body (1) according to claim 23, wherein in at least one apparatus (102) for heat treatment of a multilayer body (1), the surface element (17) is fixedly connected to the frame (13), and / or the supporting device (22) is fixedly connected to the frame (13).

25. An apparatus (102) for heat treating a multilayer body (1) according to claim 23, wherein in the first apparatus for heat treating a multilayer body (1), the surface element (17) and / or the supporting device (22) are fixedly connected to a first frame; and in the second apparatus for heat treating a multilayer body (1), the surface element (17) and / or the supporting device (22) are fixedly connected to a second frame, wherein the two frames (13) are not fixedly connected to each other.

26. A method for heat treating a multilayer body (1), comprising: The multilayer body (1) is arranged in a device (102) for thermally treating a multilayer body (1) according to any one of claims 20 to 25, and the multilayer body (1) is irradiated with heating radiation (6, 8) aimed at the cover (12) and the bottom (5).

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