JP2009188407A - Photovoltaic device with spatter-accumulated passivation layer, and method and apparatus for manufacturing such device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photovoltaic the efficiency of which is improved by increasing a hydrogen content of a passivation layer. <P>SOLUTION: A photovoltaic device having at least one semiconductor unit is manufactured by using a continuous operation type production line which includes a step for washing at least one surface of the semiconductor unit by etching, a step for drying at least the one surface of the semiconductor unit in an environment in which oxygen does not exist or the oxygen is lacked substantially, and a step for accumulating the passivation layer on at least the one surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

Background of the Invention

(Field of Invention)
The present invention refers to a method of manufacturing a photovoltaic device, an apparatus for carrying out such a method, and a photovoltaic device manufactured by them.

(Conventional technology)
Due to concerns about environmental pollution and rising energy consumption, interest in photovoltaic elements, also called solar cells, has increased. A solar cell or photovoltaic element can generate electrical energy from sunlight impinging on the solar cell or photovoltaic element. The more energy that a solar cell produces from a certain amount of light that strikes the solar cell, the better the efficiency of the solar cell. Therefore, the main purpose is to increase the efficiency of the photovoltaic device.

  The solar cell includes at least two semiconductor regions having different conductivity types that constitute a semiconductor unit. Most solar cells include a semiconductor unit made of silicon having an n-doped region and a p-doped region. A semiconductor junction is formed at the interface between the n-doped region having n-type conductivity and the p-doped region having p-type conductivity, and positive charge carriers and negative charge carriers generated by the colliding light are separated. ing. The region adjacent to the pn junction is sometimes referred to as the emitter and base. The metal contacts connected to the emitter and base can drive charge carriers out and generate electrical energy.

  One cause of solar cell electrical loss is recombination of charge carriers at the surface and interface (eg, grain boundaries) of the semiconductor material.

  In order to improve the efficiency of solar cells, it is known in the prior art to reduce the probability that charge carriers recombine on the surface of the semiconductor unit. Therefore, a so-called passivation layer is arranged on the surface of the semiconductor unit. Such a passivation layer can be formed from amorphous silicon, hydrogenated silicon nitride or hydrogenated silicon oxide. In particular, the hydrogen content plays an important role because hydrogen reduces the number of free silicon bonds, thus reducing the number of recombination sites. Thus, when using polycrystalline silicon, polycrystalline silicon, hydrogen is also beneficial for reducing the number of recombination sites within a semiconductor material such as silicon. Since polycrystalline silicon grain boundaries are also recombination sites, hydrogen can also reduce the number of free silicon bonds at the grain boundaries. In addition, hydrogen can also reduce the adverse effects of metal impurities that can again be recombination sites.

  Reflection of light impinging on the surface of the solar cell or the corresponding semiconductor unit may be another cause of the inefficiency of the solar cell. In order to reduce the reflection of colliding light, it is known to apply an antireflection coating on the surface of the solar cell on which the light collides. Such anti-reflective coatings can be formed by single or multiple transparent thin layers. Such antireflective coatings can be formed from silicon hydronitride, and the coating can also be used as a passivation layer. Accordingly, silicon hydronitride is widely used as a passivation layer and as an antireflective coating for solar cells.

  Before coating the semiconductor unit with a passivation layer or anti-reflection coating, the semiconductor unit is cleaned by an etching process to remove contaminants such as silicon dioxide generated on the silicon semiconductor unit, for example. Create a clear interface between the layer or the anti-reflective coating. Further, the reflection loss may be further reduced by structuring the surface of the semiconductor unit using etching. After etching, the semiconductor unit must be rinsed and dried to remove all etchants.

  Such surface treatment of semiconductor units by etching, rinsing, drying and / or other methods is described, for example, in the patent documents of US Pat. No. 4,705,760, US Pat. No. 5,727,578 and US Pat.

  U.S. Pat. No. 4,705,760 describes a method for forming a semiconductor device, wherein the surface of the semiconductor is treated with an aqueous ammonium fluoride / hydrogen fluoride solution prior to the deposition of the passivation layer to provide an oxygen-free nitrogen-containing atmosphere. Inside, it is subjected to plasma at a temperature of about 25 ° C. to 200 ° C. By this process, the photodetector formed by this semiconductor element exhibits improved performance characteristics. However, this plasma treatment requires a lot of labor.

  Yet another method for treating and drying the surface of a semiconductor wafer described in the above document is to rinse the surface with an aqueous fluid and remove the aqueous fluid with a so-called organic drying solvent. Including that. However, such a method is again very cumbersome because it involves the oxidation of the surface that is subject to ozone treatment to remove this organic dry solvent.

In the prior art, silane or dichlorosilane and ammonia are used as reactive gases, and the above-mentioned semiconductor surface is formed by plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD) or atmospheric pressure chemical vapor deposition (APCVD). After cleaning, a passivation layer of silicon hydronitride (SiN: H) can be deposited (K. Hezel and R. Schorner, Interface States and Fixed Charges in MNOS Structures
with APCVD and Plasma Silicon Nitride, J. Electrochem. Soc. 131 (1984) 1679-1683;
T.Pernau, Hydrogen Passivation and Silicon Nitride Deposition Using an
Integrated LPCVD Process, In Proc. 16th European Photovoltaic Solar Energy
Conference (2000) and RSR Hezel, Plasma Si nitride‐A promising dielectric to
achieve high quality silicon MIS / IL solar cells, J. Appl.Phys. 52 (1981) 3076-
3079).

In addition to chemical vapor deposition, it is known that antireflective coatings or passivation layers formed from silicon hydronitride can also be formed by reactive sputtering, according to the prior art (SW Wolke A. Jackle , R. Preu, S. Wieder, M. Ruske, SiN: H anti-reflection
coatings for c-Si solar cells by large scale inline sputtering, In Proc. 19 ^th
European Photovoltaic Solar Energy Conference, Paris (2004)).
Sputter depositing silicon hydronitride has the advantage that the hydrogen content can be better controlled during deposition and more hydrogen can be incorporated into the passivation layer and / or the adjacent semiconductor. However, due to so-called blistering at the interface between the semiconductor unit made of silicon and the passivation layer formed from hydrogenated silicon nitride (SiN: H), the amount of hydrogen introduced into the passivation layer and the semiconductor unit is It will be restricted.

(Object of invention)
The object of the present invention is to further improve the efficiency of solar cells. In particular, an object of the present invention is to increase the hydrogen content of the passivation layer and / or the semiconductor unit. Furthermore, each method or apparatus for achieving such objectives should be easy to manufacture or simple to implement.

(Technical solution)
Said object is achieved by a method according to claim 1, a device according to claim 26, a photovoltaic element according to claims 27-31. Preferred embodiments are the subject matter of the dependent claims.

  In order to improve the efficiency of a photovoltaic device or solar cell, the present invention is for manufacturing a photovoltaic device comprising at least one cleaning step, at least one drying step, and at least one deposition step. Suggest a method.

  The cleaning process is removal of contaminants and unnecessary substances in general on the surface of the semiconductor unit forming the photovoltaic element. This at least one surface that is cleaned by the cleaning process is the surface on which the passivation layer and / or antireflective coating is deposited for the purpose of reducing charge carrier recombination. Therefore, only one surface of the semiconductor unit (eg, the surface on which the light impinges on the photovoltaic element) or some or all of the surface of the semiconductor unit is cleaned and then coated with a passivation layer or anti-reflective coating. Also good.

  The surface is cleaned by etching. The expression “etching” covers all methods of removing material on the surface at the atomic level by chemical and / or physical reactions. Various types of etching methods can be used, such as chemical dry etching, chemical wet etching and / or plasma etching, specific types of chemical dry etching assisted by plasma, and the like.

  Although an etching medium is also used in physical etching such as ion beam etching, the method of removing the material is mainly characterized by removing the material by mechanical bombardment of atoms or ions. In addition, a method in which chemical etching and physical etching are combined (plasma etching or the like) may be used.

  By cleaning the surface with etching, a completely clean surface is obtained because it is predicted that even strongly adhered contaminants will be dissolved by the etching medium.

  In a preferred embodiment of the invention, the etching of the semiconductor unit, in particular a silicon-based semiconductor unit, is performed by immersing the semiconductor unit in a dilute hydrofluoric acid etching bath. Other methods may be used to apply hydrofluoric acid on the semiconductor.

  In addition to the etching, another cleaning process such as rinsing the etched semiconductor unit with water (particularly deionized water) may be performed during the cleaning process. Rinsing removes loosely deposited material without being stripped during etching.

  After the surface of the semiconductor unit is prepared by a cleaning process, a drying process is performed before depositing a passivation layer and / or an antireflection coating. In the present invention, this drying step is performed in an environment that is substantially oxygen-free or at least oxygen-deficient, thereby preventing surface reoxidation. If re-oxidation is prevented, more effective passivation of the semiconductor unit can be achieved in the subsequent deposition process. In particular, it has been found that much higher amounts of hydrogen can be introduced into passivation layers or antireflection coatings and semiconductor units (especially in polycrystalline (multi and polysilicon) silicon) than was possible in the prior art. . W. of the University of Freiburg im Breisgau As described in Wolke's November 2005 doctoral dissertation, an increase in hydrogen content beyond the optimum leads to blistering and microbubble formation at the interface between the silicon semiconductor unit and the passivation layer. . However, if the drying process according to the present invention is performed in an oxygen-free environment before depositing the passivation layer and / or anti-reflective coating, it is possible to avoid the occurrence of blistering and further increase the hydrogen content.

  Compared with the prior art described in U.S. Pat. No. 4,705,760, the surface preparation according to the invention is very simple and time-consuming and unaffected by expensive plasma treatments.

The drying process in an oxygen-free or hypoxic environment can be performed in various ways. One possibility is to flush the semiconductor unit with at least one dry inert gas (such as argon, helium, nitrogen and / or neon) in an airtight processing chamber. However, other drying methods that can be carried out without oxygen are also conceivable. For example, ambient pressure may be reduced until moisture and liquid material evaporate. The pressure may be reduced until a high vacuum level (ie, up to 10 ⁻⁷ mbar or at least 10 ⁻³ mbar).

  In addition or as an alternative, evaporation may be assisted by raising the temperature and thus drying. This heat treatment can be performed at a temperature up to 500 ° C., preferably 700 ° C. The evaporated contaminants can be exhausted from the processing chamber by suction pump means or vacuum pump means. Furthermore, the evaporated contaminants may be removed from the semiconductor unit by a gas flow created from an inert gas as described above.

  Another way to evaporate the contaminant is exposure of the semiconductor unit to microwaves.

  Whether the residual oxygen is removed or the residual oxygen content is reduced by processing a gas (such as a gas used to create a gas flow in the semiconductor unit) supplied to the processing chamber that performs the drying process Good. Alternatively or in addition, this treatment may be performed on the gas present in the processing chamber from time to time or continuously during the drying process. For this purpose, gas may be circulated.

  The deposition step of depositing a passivation layer on the surface of the semiconductor unit can be performed by a cathode evaporation method also called sputtering. Preferably, the sputtering is performed as reactive sputtering, which means that at least one reactive gas is introduced into a vacuum chamber in which reactive sputtering takes place. The reactive gas reacts with the material atomized by sputtering to produce a composition that is deposited on the substrate. In the case of the present invention, a mixture of nitrogen and ammonia gas can be used as a reactive gas mixture, and argon can be used as a processing gas for sputtering. Preferably, silicon is used as the target material for sputtering, that is, silicon atoms are generated by the sputtering process. Silicon atoms, together with nitrogen, can produce silicon nitride that is deposited on the semiconductor unit. Hydrogen is generated in the reaction chamber due to the presence of ammonia gas, and hydrogen is taken into the silicon nitride layer and the semiconductor unit by the diffusion process. Due to the production of ammonia by the reaction of nitrogen and hydrogen and vice versa, the use of a mixture of nitrogen and ammonia gas as a reactive gas mixture allows the definition of the hydrogen content in the deposited layer and in the semiconductor unit.

  Thus, the composition of the reactive gas mixture, i.e. the ratio of nitrogen to ammonia, may not only vary depending on the desired hydrogen content in the deposition layer and / or the semiconductor unit, but also changes the composition of the reactive gas mixture during deposition. This makes it possible to change the composition of the layer in the thickness direction, at least with respect to the hydrogen content.

  Since a very homogeneous layer is obtained by sputtering and reactive sputtering, the deviation of the layer thickness is less than 1.5% with respect to the entire surface.

  Yet another advantage of sputter deposition is that sputter deposition can be performed continuously in an in-line coating apparatus. For this reason, it is possible to carry out the method of the invention, in particular the deposition process, very efficiently.

  Preferably, a silicon nitride layer deposited as a passivation layer, in particular a hydrogenated silicon nitride layer, can also be designed as an antireflection coating. Therefore, the thickness of the passivation layer should not be set so that reflections occur many times by skillfully designing the interface and boundary layer, and finally the reflection of light on the surface of the semiconductor unit is reduced. Must not.

  Preferably, the cleaning step, the drying step, and the deposition step are performed so that the semiconductor unit is not exposed to the oxygen-containing atmosphere during the processing step or between the processing steps. Preferably, the cleaning process, the drying process, and the deposition process are performed as a sequence, and these processes are continuously performed from one to the next.

  This can make the design of the apparatus for performing the method advantageous, and the apparatus comprises suitable processing chambers for performing the cleaning, drying and deposition steps. These chambers can be arranged in a line so that the semiconductor units to be processed move sequentially in these processing chambers and undergo different processes.

  Such an apparatus may have a separate processing chamber for each processing step, and each processing chamber may be closed with respect to the other processing chambers so that different atmospheres can be set in the processing chamber. In this case, lock units may be installed between the processing chambers and at the entrance and exit of the apparatus.

  The photovoltaic element produced by the method of the present invention has a higher hydrogen content and is highly efficient due to this high content.

Further advantages, configurations and features of the present invention will become apparent from the following description of embodiments of the present invention. The embodiments are described with reference to the drawings, which are schematic only.
1 is a perspective view of a portion of a solar cell manufactured in accordance with the present invention. FIG. 2 is a diagram of an apparatus for carrying out the present invention. FIG. 3 is a diagram of a vacuum chamber for sputter deposition included in the apparatus of FIG.

  FIG. 1 is a perspective view of a solar cell manufactured according to the present invention. The solar cell 1 includes a semiconductor unit formed by two semiconductor layers 2 and 3 having different conductivity types. For example, the semiconductor layer 3 has n-type conductivity and constitutes the emitter of the semiconductor units 2 and 3. Therefore, the other semiconductor layer 2 having p-type conductivity serves as a base of the semiconductor junction formed by the semiconductor layers 2 and 3.

  On the side of the emitter 3 (on the side of the semiconductor units 2 and 3 where the light collides with the solar cell 1), an antireflection coating or a passivation layer 7 is provided.

  The passivation layer or anti-reflective coating 7 is made of hydrogenated silicon nitride and comprises one or more separately deposited layers. For this reason, the coating is designed such that light in the wavelength range of sunlight is not substantially reflected with respect to its thickness. This can be achieved by destructive interference or multiple reflections of partial rays reflected at each interface between layers. Therefore, it is possible to reduce or substantially prevent the reflection of colliding light.

  On top of the passivation layer or antireflection coating 7, a conduction path 8 made of a metal grid and a contact electrode 4 are installed.

  The back surface of the photovoltaic element in the form of the solar cell 1 shown in FIG. 1 is covered with a metal layer 9 and a counter electrode 5 formed by another metal grid.

  Instead of the metal grid 8 provided on the front surface (light side) of the solar cell 1, a transparent conductive layer made of indium tin oxide or the like may be disposed on the surface in the same manner as the metal layer 9 of the back contact.

  In addition to the antireflection coating 7 on the front surface (light side) of the solar cell, that is, the main surface of the emitter layer 3, a hill structure having a plurality of pyramidal protrusions and / or depressions is formed on the front side. It may be configured. Such a structure also leads to a reduction in reflection of colliding light.

  A passivation layer or antireflective coating 7 was formed according to the present invention. Since the main surface of the emitter layer 3 has been dried in an oxygen-free environment, after the cleaning process, the passivation layer 7 made of hydrogenated silicon nitride and the emitter layer 3 below made of n-doped polycrystalline silicon are A high volume of hydrogen could be introduced. The hydrogen contained in the passivation layer and the interface between the passivation layer and the emitter layer 3 reduces the number of places where charge carriers generated by colliding light are recombined. This is also true for hydrogen contained in the polycrystalline silicon of the emitter layer 3 or the base 2. Since polycrystalline silicon grain boundaries are also recombination sites for charge carriers, hydrogen can also reduce the number of such recombination sites at the grain boundaries.

  More hydrogen can be introduced into the passivation layer 7 and the polycrystalline silicon of the emitter 3 and base 2 by a deposition process carried out by sputter deposition by a drying process in which no oxygen is present in the environment. Therefore, the efficiency of the solar cell 1 is significantly increased.

  The method of the present invention will be further described in connection with FIGS. 2 and 3, which show an apparatus for carrying out the method of the present invention.

  FIG. 2 is a schematic side view of an apparatus 10 for performing the method of the present invention.

  The apparatus 10 is designed as a continuous work type production line and includes a transport path 12 for a substrate 20 placed on a substrate carrier 11.

  Along the transport path 12, different processing chambers 13, 14, 15, 16 are arranged next to each other.

  Since the processing chambers 13 to 16 are designed as airtight vacuum chambers, an oxygen-free atmosphere is obtained throughout the entire manufacturing process.

  During the initial cleaning steps performed in the processing chambers 13 and 14, an oxygen-free atmosphere is not necessary for at least some of the processing in the chamber 13, and it is also advantageous to exclude oxygen during the processing.

  The cleaning step of the method is performed in the processing chambers 13 and 14. The cleaning process includes two partial steps: chemical wet etching in the processing chamber 13 and rinsing of the substrate 20 or semiconductor unit with deionized water in the processing chamber 14.

  Accordingly, the processing chamber 13 includes an acid tank 17 containing dilute hydrofluoric acid for chemically wet etching the semiconductor units 2 and 3 on the main surface of the emitter layer 3. Etching is performed by lowering the substrate 20 into the acid baths 17, 18 as indicated by the arrows in FIG.

  After the substrate 20 formed from the semiconductor units 2 and 3 is etched, the substrate 20 is transferred to the processing chamber 14 and the second partial process of the cleaning process, that is, the semiconductor units 2 and 3 are rinsed in deionized water. Is called.

  Accordingly, the processing chamber 14 also includes a tank 19 in which deionized water is stored. The substrate 20 is lowered again into deionized water as indicated by the arrows in FIG.

  After completion of the cleaning process, the substrate 20 is moved to the next processing chamber 15 by the substrate carrier 11 along the transport path 12, and the drying process is executed.

  In the present invention, the drying step is performed in the absence of oxygen. Accordingly, the vacuum chambers 13 to 16 used as the processing chambers 13 to 16 are substantially free of oxygen. In order to create a gas flow for drying, the processing chamber 15 is provided with a gas supply 23 by which a dry inert gas 22 is introduced into the processing chamber 15 and a nozzle (see FIG. It is possible to guide the gas towards the surface of the substrate 20 by guiding means such as not shown) to achieve a gas flow along the surface of the substrate or the surface of the emitter layer 3. Due to the gas flow, other materials such as water, moisture or organic material from previous cleaning steps are absorbed into the gas flow of dry inert gas and into the outlet (not shown) of the vacuum chamber or processing chamber 15. Carried.

  In order to facilitate removal of contaminants adhering to the emitter surface or substrate surface, the temperature of the interior space of the substrate 20 or processing chamber 15 may be increased to improve contaminant evaporation. For this purpose, a heating means 24 such as a resistance heating means may be arranged inside the processing chamber 15.

  After drying in the processing chamber 15, the substrate 20 is transferred to the processing or vacuum chamber 16 by the substrate carrier 11 for sputter deposition of a passivation layer or antireflective coating.

  The processing chamber 16 is also shown in FIG. 3 for further explanation.

  The processing chamber or vacuum chamber 16 is designed as an apparatus for reactive sputtering. Accordingly, the processing chamber 16 includes a magnetron electrode 36 that is used as a cathode. The magnetron electrode 37 includes a silicon target that is atomized by the collision of argon ions in the plasma 34 generated in front of the magnetron electrode 37. The plasma 34 can be ignited by a high frequency voltage (RF voltage) applied to another microwave source (not shown) or a counter electrode constituted by a magnetron electrode 37 and the substrate carrier 11. For this purpose, a power supply 30 is installed.

  A gas supply source 31 is disposed in the processing chamber 16 in order to supply argon as a processing gas for sputter deposition to the processing chamber 16.

  A reactive gas for reactive sputtering is supplied using the second gas supply source 32. In a preferred embodiment of the present invention, the reaction gas supplied by the gas supply source 32 is a mixture of nitrogen and ammonia gas, so that nitrogen and hydrogen for deposition on the substrate 20 are provided. Nitrogen produces silicon nitride along with silicon atoms generated by atomization of the silicon target during sputtering. Hydrogen present in the gas phase of the processing chamber 16 is taken into the silicon nitride layer to produce hydrogenated silicon nitride. In addition, this hydrogen may diffuse into the substrate 20, ie the emitter 3 and base 2 of the semiconductor unit forming the substrate 20. The amount of hydrogen that can be taken into the silicon nitride and the polycrystalline silicon of the semiconductor units 2 and 3 is set by the ratio of the mixture of nitrogen and ammonia gas. Therefore, by the method of the present invention, it is possible to determine the hydrogen content of the polycrystalline silicon of the semiconductor units 2 and 3 and the silicon nitride layer deposited as a passivation layer on the semiconductor unit. Therefore, it is possible to increase the hydrogen content and reduce the number of charge carrier recombination sites in the semiconductor unit and at the interface between the passivation layer and the semiconductor unit. This also leads to an increase in the efficiency of the solar cell formed by this method.

  While the invention has been described in detail in connection with the embodiments, those skilled in the art will recognize that the invention is not limited to these embodiments and without departing from the scope of the invention as defined by the appended claims. It is apparent that variations and modifications can be made with respect to changing the combinations of all the configurations disclosed in the specification or omitting one of the configurations of the embodiments. In particular, the invention includes all possible combinations of all claims, even if each claim refers only to another claim.

Claims (33)

A method for producing a photovoltaic device having at least one semiconductor unit,
Cleaning at least one surface of the semiconductor unit by etching;
Drying at least one surface of the semiconductor unit in a substantially oxygen-free or oxygen-deficient environment;
Depositing a passivation layer on at least one surface.   The method according to claim 1, wherein the cleaning step, the drying step, and the deposition step are performed in a sequence, during which the semiconductor unit is placed in a substantially oxygen-free atmosphere.   The semiconductor unit includes at least a first region of a first conductivity type and at least a second region of a second conductivity type, and at least one semiconductor junction is formed between the first region and the second region. The method of claim 1.   The method of claim 1, wherein the cleaning step is performed by at least one method selected from the group comprising chemical dry etching, chemical wet etching, physical etching, ion beam etching and plasma etching.   The method of claim 1, wherein the cleaning step comprises an etching bath in dilute hydrofluoric acid.   The method of claim 1, wherein the washing step comprises rinsing in deionized water.   The method of claim 1, wherein the drying step comprises flushing the semiconductor unit with at least one dry inert gas selected from the group comprising argon, helium, nitrogen and neon.   The method of claim 1, wherein the drying step includes reducing the ambient pressure in the vacuum chamber to a pressure between a pressure near vacuum and a pressure below atmospheric pressure. The method of claim 1, wherein the drying step includes lowering the ambient pressure in the vacuum chamber to a pressure of 10 ⁻⁷ mbar.   The method of claim 1, wherein the drying step comprises heating the semiconductor unit to a temperature above ambient temperature.   The method of claim 1, wherein the drying step comprises heating the semiconductor unit to a temperature of 700C.   The method of claim 1, wherein the drying step comprises exposing the semiconductor unit to microwaves.   The method of claim 1, wherein the drying step includes a step of reducing the oxygen content of a gas supplied or present in an airtight chamber in which the semiconductor unit is disposed during drying.   The method of claim 1, wherein the deposition step includes deposition by sputtering.   The method of claim 1, wherein the deposition step is performed by reactive sputtering. The method according to claim 1, wherein the deposition step is performed by reactive sputtering using nitrogen and ammonia gas (NH ₃ ) as a reactive gas mixture and argon as a processing gas. The deposition process is performed by reactive sputtering using nitrogen and ammonia gas (NH ₃ ) as a reactive gas mixture, and the composition of the reactive gas mixture is set so that the hydrogen content of the deposited layer is defined. The method according to claim 1. The deposition process is performed by reactive sputtering using nitrogen and ammonia gas (NH ₃ ) as a reactive gas mixture, and the composition of the reactive gas mixture is such that the ratio of N: NH ₃ is 1:99 to 99: 1. The method according to claim 1, wherein the method is set as follows. The method of claim 1, wherein the deposition step is performed by reactive sputtering using nitrogen and ammonia gas (NH ₃ ) as a reactive gas mixture, and the composition of the reactive gas mixture is changed during deposition.   The method of claim 1, wherein the deposition step is performed continuously in an in-line coating apparatus.   The method according to claim 1, wherein the deposition step is performed in a vacuum chamber whose pressure is set to 0.1 to 15 μbar.   The method of claim 1, wherein hydrogen-containing silicon nitride is deposited as a passivation layer.   The method of claim 1, wherein the passivation layer is designed as an anti-reflective coating (ARC).   The method of claim 1, wherein the cleaning, drying and deposition steps are performed on the same surface, the surface being on one side of the semiconductor unit designed to be exposed to light.   The method of claim 1, wherein the semiconductor unit comprises one of doped and undoped single crystal and polycrystalline silicon. An apparatus for producing a photovoltaic device comprising at least one semiconductor unit,
At least one cleaning chamber for cleaning at least one surface of the semiconductor unit by etching;
At least one drying chamber for drying at least one surface of the semiconductor unit in a substantially oxygen-free or oxygen-deficient environment;
At least one deposition chamber for depositing a passivation layer on at least one surface by sputtering;
An apparatus in which a cleaning chamber, a drying chamber and a deposition chamber are arranged in series and sequentially pass through an oxygen-free atmosphere in which a semiconductor unit is closed. A semiconductor unit;
A passivation layer deposited on the semiconductor unit,
The semiconductor unit and the passivation layer contain hydrogen,
A photovoltaic device, wherein the hydrogen content in at least one of the semiconductor unit and the passivation layer is 15 atomic% or more.   The photovoltaic element according to claim 27, wherein the hydrogen content in at least one of the semiconductor unit and the passivation layer is 15 atomic% or more.   The photovoltaic element according to claim 27, wherein the hydrogen content in at least one of the semiconductor unit and the passivation layer is 20 atomic% or more.   The photovoltaic element according to claim 27, wherein the hydrogen content in at least one of the semiconductor unit and the passivation layer is 25 atomic% or more. A semiconductor unit;
A passivation layer deposited on the semiconductor unit,
The semiconductor unit and the passivation layer contain hydrogen,
A photovoltaic device, wherein the semiconductor unit has an efficiency of at least 10%.   32. The photovoltaic element according to claim 31, wherein the semiconductor unit has an efficiency of at least 15%.   32. The photovoltaic element according to claim 31, wherein the semiconductor unit has an efficiency of at least 20%.

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