Method and apparatus for manufacturing chalcogen-containing compound semiconductors

Abstract

A method for producing a chalcogen-containing compound semiconductor is provided, the method comprising: providing a processing chamber (3) with at least one substrate (5) coated with a precursor (4) of the chalcogen-containing compound semiconductor; heat-treating the at least one coated substrate (5) in the processing chamber (3), wherein during the heat treatment, a gaseous atmosphere containing at least one gaseous chalcogen compound is provided in the processing chamber (3); removing the gaseous atmosphere present after the heat treatment of the coated substrate (5) as exhaust gas from the processing chamber (3); and cooling the exhaust gas in a gas processor (13), wherein multiple types of gaseous chalcogen compounds present in the exhaust gas after the heat treatment of the coated substrate (5) are converted to liquid or solid states, thereby separating them from each other in time and space from the exhaust gas. An apparatus designed to carry out this method is also provided.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing thin-film solar cells, and more particularly to a method and an apparatus for manufacturing a chalcogen-containing compound semiconductor used as a light-absorbing material for photoelectric conversion in thin-film solar cells.

Background Art

[0002] In thin-film solar cells, the semiconductor material of the light-absorbing material for photoelectric conversion is selected so as to efficiently convert incident sunlight into current. Absorbing materials made of amorphous, microcrystalline or polycrystalline silicon, cadmium telluride (CdTe), gallium arsenide (GaAs), copper indium gallium diselenide disulfide diselenide (Cu(In,Ga)(S,Se)2), copper zinc tin sulfur selenide (CZTS from the kesterite group), and organic semiconductors are particularly suitable due to their physical properties and technical manageability. The quaternary semiconductor Cu(In,Ga)(S,Se)2 belongs to the chalcopyrite compound semiconductor and is becoming particularly important in the industrial continuous production of thin-film solar cells.

[0003] The production of chalcogen-containing compound semiconductors, particularly absorbing materials made of Cu(In,Ga)(S,Se)2, is easily carried out by a two-step process. Such a two-step process 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”, Thin Solid Films 431-432, p. 414-522 (2003).

[0004] In the first step, a precursor of a chalcogen-containing compound semiconductor ("precursor") is deposited on a substrate, and then, in the second step, the substrate coated with the precursor is heat-treated in a gaseous atmosphere containing at least one chalcogen compound. The heat treatment is generally carried out in a so-called RTP heat treatment (RTP = rapid heat treatment) or a slow batch furnace process, which induces crystal formation and phase transition of the precursor into a semiconductor layer.

[0005] To produce chalcogen-containing compound semiconductors from Cu(ln,Ga)(S,Se)2, a precursor is deposited, for example, on a glass substrate, preferably by sputtering, as a layer containing metallic copper, indium, and gallium. Generally, although not essential, at least one elemental chalcogen (selenium and / or sulfur) is deposited on the substrate as another component of the precursor by thermal deposition. In these deposition processes, the substrate temperature is usually below 100°C, and as a result, the elements remain substantially unreacted as metallic alloys and elemental chalcogens. The precursor is then thermally converted into a Cu(ln,Ga)(S,Se)2 compound semiconductor by heating in an atmosphere containing at least one chalcogen compound. For example, the precursor may contain only elemental selenium as the chalcogen, and the thermal reaction of the precursor may take place in an atmosphere containing only one sulfur compound as the chalcogen. By heat-treating the precursor in an atmosphere containing chalcogen elements, crystallization and phase transition of the precursor into a semiconductor layer can be achieved.

[0006] Accordingly, a chalcogen-containing kesterite compound semiconductor can be produced by a two-step process in which a laminate containing copper, zinc, tin, and optionally at least one elemental chalcogen is coated onto a substrate as a precursor. The precursor is then converted into a compound semiconductor by heating in a gaseous atmosphere containing at least one chalcogen compound.

[0007] Typically, in such a two-step process, while the precursor is thermally converted into a chalcogen-containing compound semiconductor, at least one chalcogen compound is added to the gaseous atmosphere in the form of a hydrogen compound, such as hydrogen sulfide (dihydrogen sulfide, H2S) or hydrogen selenide (dihydrogen selenide, H2Se).

[0008] The heat treatment of substrates coated with a precursor is performed in either an in-line system or a lamination oven. In an in-line system, coated substrates are continuously supplied to various processing chambers arranged along a process line. In a typical configuration, such an in-line system includes a filling station, at least one heating chamber in which coated substrates are rapidly heated at a heating rate of several degrees Celsius / second, and at least one cooling chamber in which coated substrates are cooled and discharged from the system. In a lamination oven, many coated substrates are slowly heated, heat-treated, and slowly cooled again simultaneously in a single oven.

[0009] Generally, the production of chalcogen-containing compound semiconductors is a high-cost and technically demanding process, requiring high temperatures, precise temperature profiles, and a limited gas atmosphere composition to achieve high efficiency and sufficiently good reproducibility. For example, in the production of high-quality Cu(ln,Ga)(S,Se)2 compound semiconductors, precise control of the vapor pressure in the gas atmosphere and the amount of at least one chalcogen compound is necessary. In particular, a sufficient and specified amount of chalcogen is required to ensure complete sulfidation and / or selenization of the precursor. Significant loss of chalcogen elements leads to incomplete conversion of the precursor into the compound semiconductor. Even minute chalcogen losses lead to recombination, i.e., loss of efficiency, and increased transients (especially vapor-heat loss) in the finished thin-film solar cell module. Using a transportable processing box or a fixed processing hood within the processing chamber is beneficial for heat treatment because it reduces the available processing space compared to a chamber cavity. This makes it easier to maintain the desired process conditions.

[0010] The chalcogen-containing gases supplied during heat treatment, particularly hydrogen sulfide and hydrogen selenide, are highly corrosive substances that erode metals at the high temperatures required during heat treatment. Furthermore, these gases are highly toxic, flammable, and combustible. Contact with mucous membranes causes persistent irritation. This means that the exhaust gases generated in the treatment chamber during the heat treatment of precursors must be purified; that is, the chalcogen compounds contained within them must be removed as much as possible before being released into the external environment. This is equally necessary for both RTP (Recycled Processing) and batch furnace processes. This purification is especially crucial when using chalcogen hydrides as the chalcogen source.

[0011] Currently, gas scrubbers (wet separation devices) are commonly used to purify exhaust gases generated during the heat treatment of precursors. For this purpose, the exhaust gas is supplied to a scrubbing tower and brought into contact with a liquid that absorbs chalcogen-containing components in the exhaust gas. For example, an iron-containing basic solution is used to absorb hydrogen sulfide or hydrogen selenide. This procedure is efficient and reliable. The residual concentration of hydrogen sulfide or hydrogen selenide in the purified exhaust gas can be reduced to 50 ppm or less. However, the resulting solid reaction product must be separated from the washing solution by pressure filtration and then disposed of as hazardous waste. To avoid this, the scrubbing solution can be downstream-treated with aerobic microorganisms to oxidize sulfur or selenium-containing substances to sulfates. This washing solution can then be used as fertilizer without any problems. As an alternative washing solution, for example, caustic soda lye mixed and diluted with hydrogen peroxide is used. Hydrogen peroxide is used to convert hydrogen sulfide or hydrogen selenide into sulfuric acid or selenic acid. Caustic soda lye neutralizes the acid produced. The use of solid absorbents in dry separators is also known.

[0012] Generally, purifying exhaust gases generated during the heat treatment of chalcogen-containing compound semiconductor precursors is costly, significantly increasing the overall cost of manufacturing thin-film solar cells. This situation is further exacerbated by the fact that residual chalcogens in the exhaust gases are lost during the purification process and cannot be reused. This is particularly disadvantageous because the usefulness rate of at least one chalcogen compound in the gaseous atmosphere within the processing chamber is relatively low (e.g., 10%), and a sufficiently high chalcogen content must always be ensured by introducing process gases into the processing chamber. [Overview of the project] [Problems that the invention aims to solve]

[0013] The objective of the present invention is to improve such a two-step process for producing chalcogen-containing compound semiconductors, thereby enabling the reliable, safe, cost-effective, simple, and ecologically acceptable manufacturing of compound semiconductors in the industrial continuous production of thin-film solar cell modules. [Means for solving the problem]

[0014] According to the proposed present invention, these and other objectives are achieved by a method and apparatus for producing chalcogen-containing compound semiconductors having the features of the combined claims. Preferred embodiments of the present invention are derived from the dependent claims.

[0015] The present invention provides a method for producing a chalcogen-containing compound semiconductor. The compound semiconductor plays the role of an absorber in a thin-film solar cell that converts sunlight into electric current.

[0016] The method according to the present invention is part of the manufacturing of a thin-film solar cell module. The thin-film solar cell module is preferably a thin-film solar cell module having a composite pane structure, the composite pane structure having a cover pane and a rear pane (e.g., a glass plate) firmly bonded to each other via a thermoplastic or crosslinked polymer intermediate layer (e.g., PVB or EVA). The present invention relates in particular to a thin-film solar cell module having a substrate structure on which a layer structure for fabricating a thin-film solar cell is applied to the light-receiving side of the rear substrate, or a superstraight structure on which a layer structure is applied to the side of the transparent cover pane away from the light-receiving side. The layer structure of the thin-film solar cell includes, in a method already known, a back electrode layer, a front electrode layer, and a photovoltaic absorbent layer disposed between the back electrode layer and the front electrode layer.

[0017] In general usage, the term "thin-film solar cell" refers to a layered structure used to manufacture thin-film solar cells, for example, those with a thickness of only a few microns, which typically requires a substrate with sufficient mechanical strength.

[0018] The substrate is made of, for example, glass, plastic, metal, or a metal alloy, and can be designed as a rigid plate or a flexible foil depending on the thickness of each layer and the specific material properties. Preferably, the substrate is made of glass, particularly soda-lime glass.

[0019] The precursor is for producing a chalcogen-containing compound semiconductor, which is thermally converted (reacted) in a gaseous atmosphere containing at least one chalcogen compound to form a compound semiconductor. The thermal conversion of the precursor is typically carried out by heating a substrate coated with the precursor, typically by an RTP process or a multilayer furnace process. For the purposes of this invention, the term "coated substrate" means a substrate coated with a precursor of a chalcogen-containing compound semiconductor.

[0020] The precursor comprises a material (metal and optionally at least one chalcogen) converted into a compound semiconductor in a gaseous atmosphere containing at least one chalcogen compound. The precursor is usually in the form of stacked layers, but not necessarily. The precursor may also consist of monolayers containing different materials. The elements of Group 6 of the periodic table are called chalcogens. The compound semiconductor, and optionally its precursor, contains at least one chalcogen, preferably sulfur and / or selenium.

[0021] The absorbent is preferably a chalcogen-containing chalcopyrite compound semiconductor, and is advantageously a ternary I-III-VI compound semiconductor consisting of the group of copper indium-gallium disulfide-diselenium, abbreviated as Cu(ln,Ga)(S,Se)2. In the above formula, indium and gallium may exist individually or in combination. The same applies to sulfur and selenium, which are chalcogens, and they may also exist individually or in combination. CISe (copper indium diselenium), CIS (copper indium disulfide), CIGSe (copper indium gallium diselenium), CIGS (copper indium gallium disulfide), or CIGSSe (copper indium gallium disulfide selenide) are particularly suitable materials for absorbents.

[0022] Similarly, the absorbent may preferably be a chalcogen-containing kesterite compound semiconductor, and preferably copper-zinc-tin-selenium sulfide (CZTS). The chalcogen-containing kesterite compound semiconductor contains at least one chalcogen, preferably sulfur and / or selenium.

[0023] Chalcogen-containing compound semiconductors are manufactured in a two-step process. For example, to prepare a Cu(ln,Ga)(S,Se)2 absorbent layer on a substrate, a precursor containing copper, indium, and gallium elements is first deposited on the substrate, preferably by sputtering, particularly after depositing the back electrode layer. Optionally, chalcogens in elemental form, preferably selenium and / or sulfur, are then coated, preferably by thermal deposition. During these deposition processes, the substrate temperature is typically below 100°C, resulting in the elements remaining substantially unreacted as a metallic alloy and chalcogen elements (selenium and / or sulfur). The coated substrate is then heated in a gaseous atmosphere containing at least one chalcogen compound to react (thermally convert) the precursor with the Cu(ln,Ga)(S,Se)2 compound semiconductor. The at least one chalcogen compound is typically present in the gaseous atmosphere in the form of a hydrogen compound, preferably hydrogen sulfide (dihydrogen sulfide, H2S) and / or hydrogen selenide (dihydrogen selenide, H2Se).

[0024] For example, the precursor may contain only elemental selenium as the chalcogen, and the thermal reaction of the precursor may take place in an atmosphere containing only one sulfur compound as the chalcogen. However, the precursor may also contain only metallic copper, indium, and gallium, and the thermal reaction may take place in a hydrogen chalcogenide, for example, first H2Se, then H2S (or vice versa), or an H2Se / H2S gas mixture.

[0025] In response to this, chalcogen-containing kesterite compound semiconductors can be manufactured in a two-step process, in which a precursor containing copper, zinc, tin, and optionally at least one elemental chalcogen (preferably sulfur and / or selenium, particularly preferably selenium only) is first coated onto the back electrode layer. Then, the coated substrate is heated in a gaseous atmosphere containing at least one chalcogen compound (preferably hydrogen sulfide (dihydrogen sulfide, H2S) and / or hydrogen selenide (dihydrogen selenide, H2Se)) to convert the precursor into a compound semiconductor.

[0026] According to the present invention, at least one substrate coated with a precursor for producing a chalcogen-containing compound semiconductor is provided in a processing chamber. The processing space is formed by an airtight or (at least during the heat treatment of the precursor) at least substantially airtight enclosure into which at least one process gas can be introduced. The processing space is, for example, the chamber cavity of the processing chamber (heating chamber). Alternatively, the processing space can be reduced in relation to the chamber cavity, whereby the coated substrate is either accommodated in a transportable processing box or covered by a fixed processing hood arranged in the processing chamber.

[0027] Then, this at least one coated substrate is heat-treated (heated). The heat treatment converts the precursor into a compound semiconductor, thereby providing a gas atmosphere containing at least one gaseous chalcogen compound in the processing chamber during the heat treatment. The term "gas atmosphere" means the gaseous environment of the precursor, particularly during the heat treatment of the precursor in the processing space. The precursor is exposed to the gas atmosphere in the processing chamber. By introducing a process gas into the processing chamber before and / or during the heat treatment of the coated substrate, the gas atmosphere in the processing chamber is adjusted in a desired manner. The supply of the process gas may be continuous or discontinuous. The process gas typically includes, in addition to at least one gaseous chalcogen compound (preferably hydrogen sulfide (dihydrogen sulfide, H2S) and / or hydrogen selenide (dihydrogen selenide, H2Se)), another gas for diluting the concentration of the gaseous chalcogen compound, preferably nitrogen (N2).

[0028] To heat the coated substrate within the processing chamber, at least one energy source is disposed outside and / or inside the processing chamber. This energy source preferably includes at least one radiant heater for generating heating radiation and is designed, for example, in the form of a radiant heater field having a one- or two-dimensional arrangement of radiant heaters. The coated substrate may be heated directly by impinging thermal radiation and / or indirectly (by heat conduction, heat radiation) by a surface heated by thermal radiation, such as the surface of the process box. Typically, the precursor is heated at a high heating rate of several degrees Celsius per second. Alternatively, the precursor is heat-treated in a stacking furnace. For this purpose, a number of coated substrates are stacked in cassettes, and these cassettes are moved into the processing chamber of the stacking furnace. Here, heating is carried out slowly via the heated walls of the furnace chamber. For uniform heating, forced convection may be carried out within the oven.

[0029] After heat treatment of the precursor and conversion to a chalcopyrite or kesterite semiconductor absorber, there is a gaseous atmosphere within the processing chamber that contains at least one gaseous chalcogen compound supplied into the gaseous atmosphere during heat treatment of the coated substrate. However, at least one other gaseous chalcogen compound may be present in the gaseous atmosphere formed from the chalcogen contained in the precursor. For example, if the precursor contains elemental selenium and hydrogen sulfide is supplied during heat treatment, the exhaust gas may contain hydrogen selenide by chemical conversion. The gas mixture may also contain nitrogen or other gases as carrier or purge gases and small amounts of oxygen or water vapor.

[0030] According to the present invention, after heat-treating a substrate coated with at least one precursor, the gaseous atmosphere is removed from the processing chamber before introducing a substrate coated with at least one more precursor into the processing chamber. A fresh gaseous atmosphere is provided for the heat treatment of at least one more (still unheat-treated) coated substrate. To this end, a process gas is typically introduced into the processing chamber before and during the heat treatment of at least one coated substrate. Preferably, at least 90%, advantageously at least 99%, of the gaseous atmosphere is removed from the processing space before at least one more coated substrate is introduced into the processing space. The gaseous atmosphere can be removed by purging and dilution with an inert gas such as nitrogen gas, or by pumping and flooding with an inert gas.

[0031] For the purposes of this invention, the term "exhaust gas" means the gaseous atmosphere removed from the processing chamber after heat treatment of at least one coated substrate.

[0032] According to the present invention, it is essential to purify the exhaust gas, thereby separating multiple (i.e., two or more) gaseous chalcogen compounds present in the exhaust gas after heat treatment of the coated substrate by converting them from the exhaust gas into liquid or solid forms. The separation of chalcogen compounds is carried out so that the chalcogen compounds are separated from each other both temporally and spatially (positionally), that is, so that the chalcogen compounds are separated from the exhaust gas sequentially (one after another) and at different locations. The exhaust gas contains at least one gaseous chalcogen compound supplied into the processing chamber during the heat treatment of at least one coated substrate. However, the exhaust gas typically further contains one or more other gaseous chalcogen compounds formed during the heat treatment.

[0033] For this purpose, the exhaust gas is cooled so that all gaseous chalcogen compounds contained in the exhaust gas are converted to a liquid or solid state (i.e., a condensed state). It is advantageous to remove the major portion of each chalcogen compound contained in the exhaust gas by converting it to a liquid or solid state, thereby removing preferably at least 90%, particularly preferably at least 99%, and even more preferably at least 99.99% of the chalcogen compounds from the exhaust gas. Preferably, each chalcogen compound is contained in the exhaust gas in a gaseous state at a concentration of less than 50 ppm after the exhaust gas has been cooled, so that the purified exhaust gas can also be released into the external environment.

[0034] Thus, exhaust gases are purified by cooling in a particularly simple, cost-effective, and ecological manner, thereby separating several gaseous chalcogen compounds from the exhaust gases by solidification or liquefaction. Furthermore, the separated (recycled) chalcogen compounds can be further utilized.

[0035] According to the present invention, by cooling the exhaust gas to a temperature below the boiling or melting point of the chalcogen compounds contained in the exhaust gas, the chalcogen compounds present in gaseous form in the exhaust gas are sequentially liquefied or solidified. By converting the gaseous chalcogen compounds in the exhaust gas into a liquid or solid aggregated state, they can be separated from the exhaust gas. For the purposes of the present invention, the term "separated chalcogen compounds" means chalcogen compounds separated from the exhaust gas by liquefaction or solidification.

[0036] Since exhaust gas contains two or more gaseous chalcogen compounds, cooling the exhaust gas to a temperature below the lowest boiling or melting point of the chalcogen compounds gradually liquefies or solidifies all of them. For this purpose, the various gaseous chalcogen compounds are each converted into a liquid or solid state and separated from each other temporally and / or spatially. This method allows for the selective separation (low-temperature separation) of individual or all chalcogen compounds from the exhaust gas. Therefore, according to the method of the present invention, different chalcogen compounds are separated from the exhaust gas both temporally and spatially. This can be achieved by a simple method of cooling the exhaust gas to a temperature lower than the different boiling or melting points of the chalcogen compounds contained in the exhaust gas at different times and places. By cooling the exhaust gas to a temperature between the two different boiling points of two chalcogen compounds, the liquefied chalcogen compound with the higher boiling point can be separated from the exhaust gas (and discharged by a gas processor). By cooling the exhaust gas to a temperature even lower than the lower boiling point, the liquefied chalcogen compound with the lower boiling point can be separated from the exhaust gas (discharged by a gas treatment unit). The same applies to the melting point of the chalcogen compound. This allows the separated chalcogen compounds to be selectively disposed of or reused in an advantageous manner; in other words, the chalcogen compounds can be recovered individually and recycled. Specifically, one or more chalcogen compounds can be selectively removed.

[0037] Exhaust gases typically contain at least two chalcogen compounds. For example, if only one gaseous chalcogen compound is already supplied into a gaseous atmosphere, such as hydrogen sulfide, the exhaust gas will generally also contain hydrogen selenide, which is formed from selenium present in the precursor. When hydrogen sulfide is separated from the exhaust gas and returned to the process area in gaseous form (recycled), the recycled gas will inevitably also contain hydrogen selenide, as hydrogen selenide has a higher boiling point than hydrogen sulfide. As a result, hydrogen selenide accumulates in the process area, significantly altering the process conditions within the process area and destabilizing the entire process. To avoid this, the recycled gas must be repeatedly diluted, but this only increases inaccuracies and process costs. According to the present invention, hydrogen sulfide and hydrogen selenide can be separated from the exhaust gas, thus avoiding the above-mentioned drawbacks. This is a major advantage of the present invention.

[0038] The exhaust gas is cooled in at least one gas processor equipped for this purpose, which includes a gas cooling device having at least one cooling zone (contact surface for the gas). The gas processor may additionally or alternatively include a gas heating device that can re-vaporize liquefied or solidified separated chalcogen compounds (after spatially separating them from the exhaust gas to avoid mixing them with the exhaust gas).

[0039] For example, at least two gas processors are provided, and exhaust gas is supplied sequentially to these gas processors. Each gas processor has at least one cooling zone (contact surface for the gas), thereby increasing the temperature of the cooling zone to which the exhaust gas is continuously supplied. In each gas processor, at least one, in particular exactly one, gaseous chalcogen compound is separated from the exhaust gas. Preferably, only one gas processor is provided having several (two or more) different cooling zones (contact surfaces for the gas) having different temperatures. The exhaust gas is continuously supplied to each cooling zone, increasing the temperature of the cooling zone, thereby separating at least one, in particular exactly one, gaseous chalcogen compound in each cooling zone.

[0040] According to one embodiment of the method of the present invention, at least one separated chalcogen compound is removed from the gas processor, i.e., spatially separated from the exhaust gas, during continuous cooling of the exhaust gas. Such a design can be easily realized by liquefying at least one chalcogen compound, because the liquid can be easily removed from the exhaust gas, for example, by a pump. In particular, at least one liquefied chalcogen compound is continuously removed during the continuous cooling of the exhaust gas. However, it is also possible to remove at least one liquefied chalcogen compound discontinuously. This allows for simultaneous spatial separation of at least one separated chalcogen compound from the exhaust gas and cooling of the exhaust gas. For example, the at least one separated chalcogen compound that has already been removed can be supplied to another gas processor equipped with a gas heating device and evaporated therein. The exhaust gas can be purified by continuous cooling until the content of a particular chalcogen compound falls below a desired maximum limit. At the same time, at least one separated chalcogen compound can be discharged from the gas processor.

[0041] According to an alternative design of the method of the present invention, at least one separated chalcogen compound and the exhaust gas are spatially separated from each other only after the exhaust gas has already cooled. This ensures that the cooling of the exhaust gas and the spatial separation of the at least one separated chalcogen compound from the exhaust gas occur sequentially, rather than simultaneously. The exhaust gas may be drawn from at least one separated chalcogen compound, i.e., the exhaust gas may be drawn from a gas processor for cooling, thereby allowing at least one separated chalcogen compound to remain in the gas processor. For example, a gas heater may be provided to vaporize the at least one separated chalcogen compound remaining in the gas processor. However, at least one separated chalcogen compound may be discharged from the gas processor, leaving the exhaust gas in the gas processor. For example, the discharged at least one separated chalcogen compound may be supplied to another gas processor having a gas heater, where it may evaporate. This design is particularly advantageous when at least one chalcogen compound solidifies, as discharging a solid from a gas processor is more difficult than discharging a liquid. After spatial separation of the exhaust gas from at least one separated chalcogen compound, the exhaust gas may be further cooled. This may be repeated until the content of the specific chalcogen compound falls below a desired maximum limit.

[0042] When chalcogen compounds are liquefied in a gas processor, the vapor pressure above the liquid is still relatively high, resulting in lower yields compared to the solidification process where the vapor pressure above the solid is very low. In this respect, conversion to a solid state may be advantageous, but recovery in continuous operation is more difficult.

[0043] For example, in a gas processor having at least two cooling zones (contact surfaces for the gas), the exhaust gas is continuously cooled in the cooling zones, and at least one, in particular exactly one, chalcogen compound is separated from the exhaust gas in each cooling zone. Each separated chalcogen compound can be selectively removed by the gas processor.

[0044] According to a preferred embodiment of the method according to the present invention, at least one separated chalcogen compound is spatially separated from the (remaining) exhaust gas and then re-evaporated, i.e., in a gaseous condensation state. This is suitable for storage purposes. However, one particular advantage is that the evaporated and at least one separated chalcogen compound can be returned to the processing chamber for heat treatment of other substrates. According to one particularly advantageous embodiment of the method according to the present invention, at least one separated chalcogen compound is supplied to the processing chamber in gaseous form before and / or during heat treatment of the coated substrate.

[0045] According to one embodiment of the method according to the present invention, at least one, more precisely one, isolated chalcogen compound is supplied to at least one buffer tank. Storage in the buffer tank allows for the subsequent easy disposal or further use of the at least one (recycled) chalcogen compound. The at least one isolated chalcogen compound can be stored in the buffer tank in a gaseous, liquid, or solid aggregated state. The temperature and / or pressure in the buffer tank can be adjusted accordingly. In particular, it is advantageous to store the at least one isolated chalcogen compound in the buffer tank in a gaseous state for subsequent supply into a processing room for heat treatment of at least one coated substrate.

[0046] The method according to the present invention can be carried out in at least two temporal stages: in the first stage, multiple chalcogen compounds are liquefied or frozen by cooling in a gas processor; in the second stage, at least one separated liquid or at least one solid is re-evaporated in the same gas processor or in another gas processor and supplied to a buffer tank. If only one gas processor is used, it is not possible to introduce further exhaust gas during evaporation, and the exhaust gas may remain in the processing chamber or be temporarily stored in another buffer tank. If a second gas processor is used, the exhaust gas can be purified in one gas processor, and in the other gas processor, heating may provide at least one separated chalcogen compound for further use.

[0047] According to one embodiment of the method of the present invention, steam water is separated from gaseous chalcogen compounds in the exhaust gas. The steam water is separated both temporally and spatially from the exhaust gas from which the chalcogen compounds have been separated. Preferably, the exhaust gas is further cooled to discharge the liquefied or solidified water from the gas processor before the gaseous chalcogen compounds solidify or liquefy. Since water has a much higher boiling and melting point than chalcogen compounds, steam water is usually separated first from the exhaust gas when the exhaust gas is cooled. If liquid or solid water is removed from the gas processor before the chalcogen compounds are separated from the exhaust gas, the separated chalcogen compounds are advantageously free of at least large amounts of water. Therefore, particularly pure chalcogen compounds can be recovered.

[0048] At least one separated chalcogen compound can be returned to the processing chamber in gaseous form. This reduces the amount of material input of at least one chalcogen compound used in a gaseous atmosphere, resulting in significant cost savings. Furthermore, this measure is very prudent from an ecological perspective as it reduces the amount of hazardous waste. To adjust the chalcogen compound content to a target level, the chalcogen compounds separated from the exhaust gas can be mixed with a diluent gas, such as nitrogen gas. It is also possible to return several chalcogen compounds separated from the exhaust gas to the processing chamber. This can be beneficial to the process, as some chalcogen compounds may not need to be recovered individually.

[0049] According to a preferred embodiment of the method of the present invention, the exhaust gas in the gas processor is cooled by contact with a cooled contact surface of a different temperature (contact cooling). The contact surface is preferably cooled by a (circulating) liquid or solid cooling medium, preferably liquid nitrogen.

[0050] The present invention also relates to a production apparatus for chalcogen-containing compound semiconductors, which is suitably configured to carry out the method according to the present invention.

[0051] The apparatus includes a processing chamber for providing at least one coated substrate coated with a chalcogen-containing compound semiconductor precursor. The processing space may be the chamber cavity of the processing chamber. The processing space may be formed by a transportable processing box or a processing hood fixedly positioned within the processing chamber. The processing chamber may be a stacking furnace including one or more cassettes, each cassette containing multiple coated substrates to be heat-treated together.

[0052] The apparatus further includes at least one energy source for heat-treating at least one coated substrate in a processing chamber, the energy source being implemented, for example, in the form of one or more radiant heaters for generating thermal radiation.

[0053] The apparatus further includes at least one gas supply line for supplying a process gas containing at least one chalcogen compound into the processing space.

[0054] The apparatus further includes at least one gas discharge line for removing a gaseous atmosphere representing exhaust gases to be cleaned from the processing space after heat treatment of at least one coated substrate.

[0055] The apparatus further includes at least one gas processor. The at least one gas processor comprises a gas cooling device for cooling the exhaust gas and converting at least one chalcogen compound contained in the exhaust gas into a liquid or solid form, and / or a gas heating device for evaporating the liquefied or solidified at least one chalcogen compound separated from the exhaust gas. In either case, the apparatus has at least one gas processor equipped with a gas cooling device. The gas processor may also be equipped with a gas heating device in addition to the gas cooling device. The gas processor may have only a gas heating device (without a gas cooling device).

[0056] Advantageously, at least two gas processors are provided, at least one of which is configured to cool the exhaust gas, and at least one gas processor is configured to evaporate at least one liquefied or solidified chalcogen compound separated from the exhaust gas. Each of the at least two gas processors may be designed to cool the exhaust gas and evaporate at least one liquefied or solidified chalcogen compound separated from the exhaust gas.

[0057] Preferably, at least two gas processors are operated in a time-recurring manner, with one gas processor separating the mixed gas from the processing space by liquefaction or freezing, and the other gas processor reheating the separated liquid or solid and supplying it to a buffer tank.

[0058] For example, the apparatus has at least two gas processors to which exhaust gas is continuously supplied, thereby enabling the separation of at least one, in particular exactly one, gaseous chalcogen compound from the exhaust gas in each gas processor. The apparatus may also include only one gas processor having at least two cooling zones (contact surfaces for the gas), in which at least one, in particular exactly one, gaseous chalcogen compound can be separated from the exhaust gas in each cooling zone.

[0059] In particular, the gas processor has a cooling device for the exhaust gas that can be advantageously cooled by a liquid cooling medium, particularly liquid nitrogen, circulating within a cooling circuit, and has at least one coolable contact surface, particularly multiple coolable contact surfaces. The gas processor may also have an internal heat source (electric heating element or supplied fluid heat carrier) for converting liquid or solid chalcogen compounds back into their original gaseous state. In particular, the gas processor may include containers for the separated chalcogen compounds distributed to each contact surface, for example, in the form of a sump.

[0060] According to one embodiment of the apparatus of the present invention, the apparatus has at least one buffer tank connected to a gas processor by a fluid conduction (fluid) method for storing at least one chalcogen compound removed from exhaust gas. The buffer tank may be designed in particular to store two or more chalcogen compounds, preferably in separate forms.

[0061] According to an embodiment of the apparatus according to the present invention, at least one gas processor and / or at least one buffer tank are fluidly coupled to a gas supply line to a processing chamber. The processing space may have a first gas supply line used to introduce a main process gas containing at least one chalcogen compound that has not been separated from the exhaust gas into the processing space via this first gas supply line, and the processing space may also have a second gas supply line used to introduce a second process gas containing (or composed of) at least one chalcogen compound that has been separated from the exhaust gas into the processing space. Alternatively, the first gas supply line and the second gas supply line may be combined as a common gas supply line. In particular, the main process gas and the secondary process gas can be mixed before or during introduction into the process area.

[0062] For the configuration of the apparatus for manufacturing chalcogen-containing compound semiconductors for carrying out the method according to the present invention, refer further to the above description of the method according to the present invention.

[0063] Various embodiments of the present invention can be realized individually or in any combination. In particular, the features described above and those described below can be used not only in the combinations shown but also in other combinations or unique positions without departing from the scope of the present invention. [Brief explanation of the drawing]

[0064] Next, the present invention will be described in more detail with reference to the attached drawings. [Figure 1] This is a schematic diagram of an embodiment of a manufacturing apparatus for chalcogen compound semiconductors. [Figure 2] This is a flowchart illustrating the process steps of the method for producing a chalcogen-containing compound semiconductor according to the present invention. [Modes for carrying out the invention]

[0065] First, consider Figure 1, which schematically illustrates the manufacturing apparatus for chalcogen-containing compound semiconductors, as shown in reference number 1.

[0066] Apparatus 1 includes, for example, a processing chamber wall 2 formed by a process box or furnace chamber, and defines a processing chamber 3 for housing at least one substrate 5 coated with a precursor 4. The precursor 4 is deposited on the surface 6 of the substrate 5 for producing a chalcogen-containing compound semiconductor. The processing wall 2 comprises a bottom wall 7, an upper wall 8, and side walls 9 that connect the bottom wall 7 and the upper wall 8 to each other and also serve as spacers between the bottom wall 7 and the upper wall 8. The bottom wall 7, the upper wall 8, and the side walls 9 form a processing chamber 3 in which the substrate 5 coated with the precursor 4 can be heat-treated. The substrate 5 is located, for example, inside the bottom wall 7. If the processing chamber wall 2 is formed by a process box, the bottom wall 7, the upper wall 8, and the side walls 9 can be detachably connected to each other. If the processing chamber wall 2 is formed by a lamination furnace, the bottom wall 7, the upper wall 8, and the side walls 9 can be firmly connected to each other. In particular, the processing chamber wall 2 may be formed by an annular furnace.

[0067] At least one of the substrates 5 is, for example, a glass plate. A back electrode layer (details not shown) is coated on the surface 6 of the substrate 5. On the back electrode layer is a precursor 4 that is thermally converted into a chalcogen-containing compound semiconductor. For example, to produce a Cu(ln,Ga)(S,Se)2 absorbent layer, the precursor 4 is composed of different individual layers containing copper, indium, and gallium, which are coated, for example, by sputtering. Furthermore, the precursor 4 may contain chalcogen elements, preferably selenium and / or sulfur, in elemental form, which are preferably coated by thermal deposition. In the processing chamber 3, the precursor 4 is reacted by heating in a gaseous atmosphere containing at least one chalcogen compound, preferably selenium and / or a sulfur compound, to form a Cu(ln,Ga)(S,Se)2 compound semiconductor. For example, the precursor 4 contains only elemental selenium as the chalcogen element, and the thermal reaction of this precursor is carried out in a gaseous atmosphere containing only sulfur as chalcogen in a sulfur compound (e.g., hydrogen sulfide). The thermal conversion of the precursor 4 is carried out in the processing chamber 3.

[0068] Adjacent to and very close to the top wall 8 is a radiator field 10 as an energy source, having a number of heating radiators (e.g., halogen lamps, infrared radiators, or surface radiators) arranged in a one-dimensional or two-dimensional array to emit heating radiation to heat the top of the precursor 4. Similarly, adjacent to and very close to the bottom wall 7 is another radiator array as a bottom energy source, not shown in Figure 1 for brevity. In the laminated oven, preferably, the side walls 9 are also heated by the energy source. The radiant heaters of the radiator array 10 emit heating radiation that partially passes through the top wall 8 (which is, for example, partially transparent) and strikes the precursor 4. Some of the heating radiation is absorbed by the top wall 8, heating the top wall 8, which also emits thermal radiation, which in turn heats the precursor 4. Bottom heating of the precursor 4 by a bottom radiator field (not shown) is carried out similarly. In a laminated oven with several substrates, thermal energy must also be supplied to the internal substrates by convection.

[0069] After depositing the substrate 5 coated with precursor 4 into the processing chamber 3, or after inserting a cassette having multiple coated substrates, the processing chamber 3 is closed and the processing chamber 3 is filled with a (main) processing gas containing at least one chalcogen compound via the first gas supply line 11 leading to the processing chamber 3. Subsequently, the coated substrate 5 is tempered at a tempering rate of several degrees Celsius / second, for example, 5 degrees Celsius / second. By heating multiple substrates relatively slowly in the lamination furnace, uniform heating by convection and radiation is enabled, avoiding glass breakage and bending. During the tempering of the coated substrate 5, the main process gas may be supplied to the processing chamber 3 if necessary. For example, the precursor 4 contains only selenium (Se) as chalcogen, and hydrogen sulfide (H2S) diluted with nitrogen gas (N2) is supplied to the processing chamber 3 as the main process gas. Alternatively, the precursor does not contain chalcogen, and H2Se and H2S are supplied as the main process gas. In Figure 1, the arrow next to the first gas supply line 11 illustrates the supply of the main process gas into the processing chamber 3.

[0070] After the heat treatment of precursor 4 is completed and the precursor 4 is converted into a chalcogen-containing compound semiconductor, the gaseous atmosphere in the processing chamber 3 is withdrawn from the processing chamber 3 via the gas discharge line 12 that leads into the processing chamber 3. The extraction of the gaseous atmosphere from the processing chamber 3 is indicated by an arrow above the gas discharge line 12 in Figure 1. The extracted gaseous atmosphere is the exhaust gas that is purified.

[0071] For this purpose, the gas exhaust line 12 is fluid-conductively connected to the gas processor 13. The exhaust gas is introduced into the gas processor 13 via the gas exhaust line 12. The gas processor 13 is used to actively cool the exhaust gas, thereby removing at least 99% of several chalcogen compounds, in particular at least one chalcogen compound supplied into the main process gas (here, for example, hydrogen sulfide and / or hydrogen selenide). For this purpose, the exhaust gas is cooled to a temperature below the boiling point of each chalcogen compound so that the chalcogen compounds can be liquefied and separated from the exhaust gas. The exhaust gas may also be cooled to a temperature below the melting point of each chalcogen compound so that it is temporarily separated as a solid. The exhaust gas thus purified can then be discharged into the external environment via the gas outlet 14.

[0072] Although only schematically illustrated, the gas processor 13 includes a cooling device 23 having a cooling chamber 20 into which exhaust gas can be introduced. The cooling chamber 20 is equipped with cooling contact surfaces 21, 21' for cooling the exhaust gas. The contact surfaces 21, 21' are cooled by their respective cooling media, here, for example, a liquid cooling media circulating within a cooling circuit, in particular liquid nitrogen. The exhaust gas is supplied sequentially to the two contact surfaces 21, 21', and the temperatures of the two contact surfaces 21, 21' are different. The temperature of the downstream contact surface 21' in the direction of exhaust gas flow is lower than that of the upstream contact surface 21. At each contact surface 21, 21', chalcogen compounds are separated from the exhaust gas. For example, hydrogen selenide is separated at the first contact surface 21, and hydrogen sulfide is separated at the second contact surface 21'. Each contact surface 21, 21' forms a cooling zone for the exhaust gas. The contact surfaces 21 and 21' each have containers 24 and 24' (sumps) for a separated (e.g., liquid) chalcogen compound, as schematically shown in Figure 1.

[0073] At least one chalcogen compound separated from the (recycled) exhaust gas is transferred from the gas processor 13 to the buffer tank 16 via the connection line 15. Figure 1 is merely a schematic representation of this. In particular, the connection line 15 can also be configured as two separate fluid lines to supply two separated (e.g., liquid) chalcogen compounds in containers 24, 24' with contact surfaces 21, 21' together to the buffer tank 16. The transfer of at least one recycled chalcogen compound to the buffer tank 16 is illustrated in Figure 1 by an arrow above the connection line 15.

[0074] At least one liquefied or solidified chalcogen compound may be removed by the gas processor 13 during or after the cooling of the exhaust gas without being transported to the buffer tank 16. In particular, in the case of liquefaction, removal of the exhaust gas from the gas processor 13, especially continuous removal, is possible even during the cooling of the exhaust gas. The gas processor 13 can be operated in two stages if at least one chalcogen compound condenses as a solid. In the first stage, at least one chalcogen compound is separated from the exhaust gas by solidification. In the second stage, the solid is vaporized and removed by the gas processor 13, and can be collected in particular in the buffer tank 16. Although not shown in Figure 1, preferably at least two gas processors 13 are used, one gas processor 13 cooling the exhaust gas and separating at least one chalcogen compound, and the other gas processor evaporating the separated at least one chalcogen compound.

[0075] Alternatively, instead of a single gas processor 13 having two contact surfaces 21, 21', two gas processors, each having one contact surface, may be provided to sequentially supply exhaust gas to the two gas processors.

[0076] Within the buffer tank 16, at least one recycled chalcogen compound can be stored in gaseous, liquid, or solid form, depending on the pressure and temperature within the buffer tank 16. In particular, in liquid and solid form, at least one recycled chalcogen compound can be easily transferred for further use or disposal, as illustrated by the first buffer tank outlet 17 and the arrow below it. When stored in gaseous form, the recycled chalcogen compound can be supplied directly to the processing chamber 3. Otherwise, pre-evaporation is required. In particular, two different recycled chalcogen compounds can be stored separately in the buffer tank 16.

[0077] Furthermore, the buffer tank 16 has a second buffer tank outlet 18 which is fluidly connected to a second gas supply line 19 leading to the processing chamber 3. At least one, in particular exactly one, recycled chalcogen compound (e.g., hydrogen sulfide) can be introduced into the processing chamber 3 as a secondary process gas via the second gas supply line 19. This is illustrated by the arrow next to the second buffer tank outlet 18. In particular, this reduces the amount of chalcogen compound (e.g., hydrogen sulfide) added to the main process gas during the heat treatment of at least one other coated substrate 5, thereby saving a significant amount of material and cost. The arrow next to the second gas supply line 19 illustrates the supply of recycled chalcogen compound as a secondary process gas into the processing chamber 3. It is conceivable to specifically adjust the amount of chalcogen compound in the secondary process gas by mixing the recycled chalcogen compound with a diluent gas, such as nitrogen (N2). It is also possible to mix the secondary process gas and the main process gas before introducing them into the processing chamber 3, thereby adjusting the concentration of (multiple) chalcogen compounds, in particular, with the diluent gas of the main process gas. Thus, the second gas supply line 19 can be omitted. The connection line is adequately protected by a valve. In this way, cyclic operation can also be controlled. Preferably, only a single chalcogen compound (e.g., hydrogen sulfide) is supplied into the processing chamber, so that other chalcogen compounds (e.g., hydrogen selenide) separated from the exhaust gas are used elsewhere or disposed of. In this way, process conditions can be kept stable, thereby avoiding the accumulation of hydrogen selenide, in particular, in the process area.

[0078] It will be understood that the gas processor schematically illustrated in Figure 1 may further have two or more contact surfaces (cooling zones) in order to separate two or more gaseous chalcogen compounds from exhaust gas.

[0079] During the heat treatment of precursor 4, chalcogens in precursor 4 may (slightly) enter the gaseous atmosphere, so the exhaust gas may contain chalcogen compounds originating from chalcogens in precursor 4. These chalcogen compounds can be separated from the exhaust gas in the gas processor 13, either together with at least one chalcogen compound from the first process gas, or by themselves. The mixture of chalcogen compounds separated from the exhaust gas may be stored in a buffer tank 16 and / or supplied to the processing chamber 3, thereby facilitating process control. Similarly, water vapor can also be separated from the exhaust gas.

[0080] If necessary, the gas processor 13 is equipped with a heating device 22 to facilitate maintenance, but it is also used for the recovery (evaporation) of liquefied or condensed chalcogen compounds.

[0081] Figure 2 shows a flowchart illustrating a method for producing chalcogen-containing compound semiconductors.

[0082] In this process, in the first step I, a substrate 5 coated with a chalcogen-containing compound semiconductor precursor 4 is provided in the processing chamber 3. In the second step II, the precursor 4 is heat-treated in the processing chamber 3, and during this heat treatment, a gaseous atmosphere containing at least one chalcogen compound is provided in the processing chamber 3. In the third step III, after the heat treatment of the precursor 4, the gaseous atmosphere present in the processing chamber 3 is removed as exhaust gas, and in the fourth step, the exhaust gas is purified, and the multiple types of chalcogen compounds contained in the exhaust gas (gaseous chalcogen compounds provided in the gaseous atmosphere during the heat treatment of at least one coated substrate, and / or formed during the heat treatment) are at least partially removed from the exhaust gas by cooling the exhaust gas to liquefy or solidify the chalcogen compounds.

[0083] The gas processor 13 facilitates the cryogenic separation of chalcogen compounds from exhaust gas. The melting and boiling points of the exhaust gas sample components are shown in the following table: JPEG0007832799000001.jpg46170

[0084] Therefore, by increasing the cooling of the exhaust gas to a temperature below 0°C, residual water (H2O) can be prevented from the outset. Subsequently, these (toxic) gases can be separated from the exhaust gas at temperatures near the boiling points of hydrogen selenide (-41°C) and hydrogen sulfide (-60°C), and by cooling to an intermediate temperature, individual separation is possible. By cooling the exhaust gas to a temperature below the melting points of hydrogen selenide (-66°C) and hydrogen sulfide (-86°C), these compounds can also be frozen, while nitrogen (N2) and oxygen (O2) remain in gaseous form. Since the maximum temperature of liquid nitrogen is -195.8°C, the cooling surface of the cooling device 23 can be effectively cooled for the cryogenic separation of chalcogen compounds.

[0085] As described above, the present invention provides an improved method for producing chalcogen-containing compound semiconductors and a corresponding production apparatus, which can purify the exhaust gas generated during the heat treatment of the precursor by cooling it in a simple and inexpensive way (cryogenic separation of chalcogen compounds).

[0086] One or more recycled chalcogen compounds can be reused in a particularly advantageous manner, especially as a (by)process gas in the heat treatment of at least one other coated substrate. This can save a large amount of material and cost in the manufacture of thin-film solar cells. Furthermore, the method according to the present invention is highly advantageous from an ecological standpoint due to the recycling of toxic chalcogen compounds and the resulting reduction of hazardous waste. [Explanation of symbols]

[0087] 1 device 2 Processing chamber wall 3 Processing Chamber 4. Precursors 5 circuit boards 6 surface 7 Bottom wall 8 Upper wall 9 side wall 10. Radiator Field 11. First Gas Supply Line 12 Gas discharge lines 13 Gas processor 14 Gas outlet 15 connection lines 16 Buffer Tank 17. Outlet of the first buffer tank 18. Second buffer tank outlet 19. Second gas supply line 20 Cooling Chamber 21,21' Contact surface (cooling zone) 22 Heating device 23 Cooling device 24,24' container

Claims

1. A method for producing a chalcogen-containing compound semiconductor, The steps include providing a processing chamber (3) containing at least one substrate (5) coated with a precursor (4) containing the metal and cargogen of the chalcogen-containing compound semiconductor, A step of heat-treating the at least one coated substrate (5) in the processing chamber (3), wherein during the heat treatment, a gaseous atmosphere containing at least one gaseous chalcogen compound is provided in the processing chamber (3), The steps include removing the gaseous atmosphere present after the heat treatment of the at least one coated substrate (5) from the processing chamber (3) as exhaust gas, A step of cooling the exhaust gas in a gas processor (13) to a temperature lower than the boiling point or melting point of the at least one gaseous chalcogen compound, such that at least 99% of the at least one gaseous chalcogen compound is removed from the exhaust gas, wherein the mixture of multiple types of gaseous chalcogen compounds present in the exhaust gas after the heat treatment of the at least one coated substrate (5) is converted into either a liquid or solid state, thereby separating them temporally and spatially at an upstream cooling contact surface (21) having different temperatures for cooling the exhaust gas, and a downstream cooling contact surface (21') having a lower temperature than the upstream cooling contact surface (21), thereby separating them from the exhaust gas into hydrogen selenide and hydrogen sulfide. A method for producing a chalcogen-containing compound semiconductor, comprising the steps of: transferring at least the hydrogen sulfide separated from the exhaust gas at the downstream cooling contact surface (21') in gaseous form to a buffer tank (16) connected to the gas processor (13), and supplying it to the processing chamber (3) via a gas supply line (19) connected to the buffer tank (16).

2. At least one chalcogen compound separated from the exhaust gas is removed from the gas processor (13) during the cooling of the exhaust gas. The method according to claim 1.

3. At least one chalcogen compound separated from the exhaust gas, or the exhaust gas, after cooling the exhaust gas, is discharged from the gas processor (13). The method according to any one of claims 1 to 2.

4. Evaporate at least one chalcogen compound separated from the exhaust gas. The method according to any one of claims 1 to 3.

5. The water vapor contained in the exhaust gas is converted into a liquid or solid state, thereby separating it from at least one of the gaseous chalcogen compounds present in the exhaust gas. The method according to any one of claims 1 to 4.

6. A mixture of several gaseous chalcogen compounds separated from the exhaust gas is supplied in gaseous form to the processing chamber (3). The method according to any one of claims 1 to 5.

7. An apparatus for producing a chalcogen-containing compound semiconductor by the method described in any one of claims 1 to 6, The processing chamber (3) for providing the at least one substrate (5) coated with the precursor (4) of the chalcogen-containing compound semiconductor, The processing chamber (3) includes at least one energy source (10) for heat-treating the at least one coated substrate (5), At least one gas supply line (19) for supplying the hydrogen sulfide separated from the exhaust gas into the processing chamber (3), The processing chamber (3) is provided with at least one gas discharge line (12) for discharging a gaseous atmosphere as exhaust gas, An apparatus comprising at least one gas processor (13) capable of cooling the exhaust gas so that, after the heat treatment of the at least one coated substrate (5), the mixture of several gaseous chalcogen compounds present in the processing chamber (3) is converted into a liquid or solid state and separated from the exhaust gas.

8. The processing chamber (3) is connected to a gas processor (13) designed to sequentially separate a mixture of multiple types of gaseous chalcogen compounds from the exhaust gas. The apparatus according to claim 7.

9. The system includes at least one heating device (22) for vaporizing at least one liquid or solid chalcogen compound separated from the exhaust gas. The apparatus according to claim 8.

10. The gas processor (13) is fluidly connected to at least one buffer tank (16) for storing at least one of the gaseous chalcogen compounds separated from the exhaust gas. The apparatus according to any one of claims 7 to 9.

11. The gas processor (13) is connected to the processing chamber (3) via the gas discharge line (12), or the buffer tank (16) having a buffer tank outlet (18) is connected to the processing chamber (3) via the gas supply line (19) connected to the buffer tank outlet (18) by fluid conduction. The apparatus according to any one of claims 7 to 10.

12. The processing chamber (3) is connected to at least two of the gas processors (13), and the at least two gas processors (13) are designed such that one gas processor (13) evaporates at least one chalcogen compound separated from the exhaust gas, and the other gas processor (13) separates at least one gaseous chalcogen compound from the exhaust gas. The apparatus according to any one of claims 7 to 11.

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