WO2012046746A1 - PROCÉDÉ DE FABRICATION DE COUCHE D'ABSORPTION DE LUMIÈRE POUR CELLULE SOLAIRE À FILM MINCE SEMI-CONDUCTEUR COMPOSÉ, ET CIBLE DE PULVÉRISATION CATHODIQUE D'ALLIAGE In-Cu - Google Patents

PROCÉDÉ DE FABRICATION DE COUCHE D'ABSORPTION DE LUMIÈRE POUR CELLULE SOLAIRE À FILM MINCE SEMI-CONDUCTEUR COMPOSÉ, ET CIBLE DE PULVÉRISATION CATHODIQUE D'ALLIAGE In-Cu Download PDF

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WO2012046746A1
WO2012046746A1 PCT/JP2011/072899 JP2011072899W WO2012046746A1 WO 2012046746 A1 WO2012046746 A1 WO 2012046746A1 JP 2011072899 W JP2011072899 W JP 2011072899W WO 2012046746 A1 WO2012046746 A1 WO 2012046746A1
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film
alloy
alloy film
sputtering
forming
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藤井　秀夫
富久　勝文
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株式会社神戸製鋼所
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/036—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
    • H01L31/0392—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
    • H01L31/03923—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate including AIBIIICVI compound materials, e.g. CIS, CIGS
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
    • C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
    • C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
    • H01L31/0264—Inorganic materials
    • H01L31/032—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
    • H01L31/0322—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/072—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN heterojunction type
    • H01L31/0749—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN heterojunction type including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/541—CuInSe2 material PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a method for producing a light-absorbing layer for a solar cell using a compound semiconductor thin film containing Cu, and at least one element selected from the group consisting of In, Ga, and Al, and Se as a light-absorbing layer, and the above
  • the present invention relates to an In—Cu alloy sputtering target used in the method.
  • a compound semiconductor thin film containing Cu, a group 13 element of In, Ga, and Al (based on a long-period periodic table); and Se is widely used as a light absorption layer of a solar cell.
  • a Cu + In + Se) -based or CIGS (Cu + In + Ga + Se) -based light absorption layer can be used. It is known that a CIGS-based light absorption layer containing Ga has a slightly larger band gap than CIS and improves the conversion efficiency of sunlight.
  • FIG. 1 shows an example of the configuration of a solar cell using a CIGS compound semiconductor thin film as a light absorption layer.
  • the CIGS thin film positive battery shown in FIG. 1 has a Mo back electrode, a CIGS thin film light absorption layer, a CdS buffer layer, a ZnO thin film window layer, an ITO thin film transparent electrode layer on a soda lime glass (SLG) substrate. , Al or NiCr electrodes.
  • the light absorbing layer forming method is roughly classified into three methods, vapor deposition, sputtering, and coating.
  • the sputtering method has already been mass-produced on a large substrate of 1 m square or more in applications such as liquid crystal displays, and has already been mass-produced in Japan due to the fact that film formation of a large area is easier than other methods. Has been started.
  • a Cu—Ga alloy film and a pure In film are sequentially laminated on a substrate using a Cu—Ga alloy target and a pure In target made of Cu (group 11 element) and Ga (group 13 element).
  • a CIGS light absorption layer is manufactured by performing a heat treatment step (referred to as selenization) at about 500 to 550 ° C. in an atmosphere containing Se.
  • the precursor thin film before selenization is usually called a precursor. According to the above method, a precursor made of a laminate of a Cu—Ga alloy film and a pure In film can be obtained.
  • Patent Document 1 As a method for producing a precursor of a CIGS light absorption layer by using a sputtering method, Patent Document 1 and Patent Document 2 can be cited. Among them, Patent Document 1 solves problems such as “in the case of a CIGS film produced by a sputtering method, Ga segregates on the surface side, and Ga distribution in the film thickness direction becomes non-uniform, so that good battery characteristics cannot be obtained”. Therefore, the following three embodiments (I) to (III) are disclosed in order from the substrate side.
  • a first step of forming an In thin film or a Cu thin film, a second step of forming a Cu—Ga alloy thin film, and a third step of forming a Cu thin film And a production method comprising: (II) As a second embodiment, a first step of forming an In thin film or a Cu thin film, a second step of forming a Cu—Ga alloy thin film, and a third step of forming an In thin film And a production method comprising: (III) As a third embodiment, a first step of forming a Cu—Ga alloy thin film, a second step of forming an In thin film or a Cu thin film, and a first step of forming a Cu—Ga alloy thin film 3.
  • a manufacturing method comprising:
  • Patent Document 2 when forming an In layer by sputtering, due to the physical properties of In having a low melting point and a large surface tension, In crystals grow in a granular form at a relatively low temperature, and a rough In having a gap. A film (island-like In film) is formed on the surface, but the portion corresponding to the gap becomes Cu-rich during subsequent selenization, and a low-resistance Cu—Se compound is locally generated, resulting in battery characteristics.
  • a method of forming an In layer in a sputtering gas atmosphere to which oxygen is added is disclosed.
  • Ga has a very low melting point of about 29.8 ° C., and under the situation where island-like In crystals are deposited as described above, oxidation of Ga oxide, CuGa oxide, etc. at the time of precursor formation prior to selenization. Since the product is easily formed on the outermost surface, the film quality uniformity of the CIGS-based thin film after selenization is deteriorated and reproducibility is inferior.
  • the target-substrate distance also changes and the effective target surface temperature and substrate temperature also vary. Therefore, it becomes difficult to control the film thickness of the pure In film itself and to ensure the reproducibility of the film quality.
  • the pure In target is disadvantageous in that deformation during continuous film formation is large and high power film formation is difficult, and as a result, it is difficult to improve productivity.
  • the present invention has been made in view of the above circumstances, and its object is to prevent discontinuous layer formation (formation of island-like In film) when a pure In film is formed by sputtering, and preferably Ga is used.
  • a pure In film is formed by sputtering, and preferably Ga is used.
  • the manufacturing method of the light absorption layer for compound thin film solar cells which can suppress the oxidation of Ga, and the sputtering target used suitably for formation of the said light absorption layer Is to provide.
  • the present invention provides the following method for producing a light absorbing layer for a compound semiconductor thin film solar cell and an In—Cu alloy sputtering target.
  • a method for producing a light-absorbing layer for a compound semiconductor thin film solar cell containing Cu,; In, and at least one element of Ga and Al; and Se A method for producing a light-absorbing layer for a compound semiconductor thin film solar cell, comprising a step of forming an In—Cu alloy film by sputtering.
  • An In—Cu alloy sputtering target used for producing a light-absorbing layer for a compound semiconductor thin film solar cell containing Cu, In, at least one element of Ga and Al, and Se.
  • An In—Cu alloy sputtering target comprising 30 to 80 atomic% of Cu, the balance being In and inevitable impurities.
  • a pure In film is not formed as in the prior art, but an In—Cu alloy film is used.
  • a continuous In—Cu alloy film can be obtained instead of the In film.
  • a light-absorbing layer having a uniform composition within the same plane and good film quality ie, excellent in-plane uniformity
  • the provision of an absorption layer is highly expected.
  • the subsequent selenization step is performed by a surface-to-surface reaction (layer-by-layer), so that the in-plane uniformity is further improved.
  • FIG. 1 is a cross-sectional view schematically showing a configuration of a typical solar cell using a CIGS compound semiconductor thin film as a light absorption layer.
  • FIG. 2 is an SEM photograph showing the state of the thin film when a pure In film is formed on the Cu—Ga alloy film by sputtering.
  • FIG. 3 is an SEM photograph showing the state of the thin film when an In—Cu alloy film (Cu content ⁇ 35 atomic%) is formed on the Cu—Ga alloy film by sputtering.
  • FIG. 4 is an SEM photograph showing the state of the thin film when an In—Cu alloy film (Cu content ⁇ 55 atomic%) is formed on the Cu—Ga alloy film by sputtering.
  • FIG. 5 is an SEM photograph showing the state of the thin film when an In—Cu alloy film (Cu content ⁇ 60 atomic%) is formed on the Cu—Ga alloy film by sputtering.
  • the present inventors use a compound semiconductor thin film containing Cu as typified by a CIGS thin film; at least one element selected from the group consisting of In, Ga and Al; and a compound semiconductor thin film containing Se as a light absorption layer.
  • Problems when depositing pure In film by sputtering when forming a light absorption layer for use (strictly speaking, a precursor before selenization) by sputtering (discontinuous layer formation by island-like In film formation)
  • a continuous In—Cu alloy film can be formed by using a manufacturing method including a process of forming an In—Cu alloy film by sputtering instead of forming a pure In film as in the prior art.
  • the present invention has been completed.
  • FIGS. 2 to 5 show that when a pure In film or an In—Cu alloy film is formed on a Cu—Ga alloy film by sputtering, the Cu content in the In—Cu alloy film is changed. It is a SEM photograph which shows the result of having analyzed the state of the outermost surface of the said alloy film in SEM (magnification: 3000 times).
  • FIG. 2 is a diagram showing a state in which the amount of Cu is 0, that is, when a pure In film is formed on a Cu—Ga alloy film, and an island-like In film is formed instead of a continuous layer. I understand.
  • FIGS. 3 to 5 are examples in which the In—Cu alloy film used in the present invention is formed
  • FIG. 3 shows the Cu amount ⁇ 35 atomic%
  • FIG. 4 shows the Cu amount ⁇ 55 atomic%
  • any In—Cu alloy film produces a continuous film. This prevents the Cu—Ga film from being exposed, so that the oxidation of Ga during atmospheric transportation can be suppressed, and the subsequent selenization process is performed by a surface-by-layer reaction. Therefore, the in-plane uniformity is further improved.
  • the surface properties of the In—Cu alloy film can be changed depending on the Cu content. As the amount of Cu increases (FIG. 3 ⁇ FIG. 4 ⁇ FIG. 5), the island-like In region existing on the outermost surface (uneven shape) It can be seen that a flat continuous film with small unevenness can be obtained. This island-like In region is formed on the In—Cu alloy film (continuous film), and as described later, the preferable amount of Cu in the In—Cu alloy film is appropriately controlled in the present invention. It is presumed that there is no risk of a solar cell performance degradation due to the formation of the island-shaped In region. Further, it is presumed that the effect of the continuous film formation described above is further promoted by forming a flat continuous layer with few irregularities.
  • the amount of Cu contained in the In—Cu alloy film can be formed so that a desired continuous film can be formed and formation of a light absorption layer for a solar cell with high photoelectric conversion efficiency can be realized.
  • it is generally controlled within the range of 30 to 80 atomic%, but from FIGS. 3 to 5 above, if the amount of Cu is within the above range, a desired continuous film of In—Cu alloy (preferably It can be seen that a continuous film whose surface is further planarized is obtained.
  • the method for producing a light absorption layer for a solar cell according to the present invention is characterized in that it includes a step of forming an In—Cu alloy film by sputtering. Specifically, a desired light absorption layer (Cu and; at least one element selected from the group consisting of In, Ga, and Al; and a light absorption layer of a compound semiconductor thin film containing Se) is obtained.
  • a desired light absorption layer Cu and; at least one element selected from the group consisting of In, Ga, and Al; and a light absorption layer of a compound semiconductor thin film containing Se
  • the manufacturing process includes at least a step of forming an In—Cu alloy film by a sputtering method, and typically includes an embodiment including the following steps: A first step of forming a Cu—Ga alloy film or a Cu—Al alloy film by sputtering, a second step of forming an In—Cu alloy film by sputtering, and a pure In film by sputtering as necessary. And a third step of sequentially forming a film.
  • a Cu—Ga alloy film or a Cu—Al alloy film (thickness: about 0.05 to 1.0 ⁇ m) is formed on a back electrode such as Mo by sputtering.
  • This film forming process is known, and a commonly used Cu—Ga alloy film or Cu—Al alloy film forming method can be appropriately employed.
  • the methods of Patent Documents 1 and 2 described above can also be referred to.
  • a typical example of the sputtering target (hereinafter sometimes abbreviated as “target”) used in the above process is a Cu—Ga alloy target or a Cu—Al alloy target.
  • composition of the alloy target By adjusting the composition of the alloy target, The composition of the Cu—Ga alloy film or Cu—Al alloy film can be adjusted, and finally, a light absorption layer having a composition with high photoelectric conversion efficiency can be realized.
  • the composition of the Cu—Ga alloy film or the Cu—Al alloy film may be adjusted by chip-oning a Ga element or Al element metal on a pure Cu target.
  • the preferable content of Ga or Al in the Cu—Ga alloy film can be appropriately set appropriately according to the desired composition of the light absorption layer, the ease of manufacturing the alloy sputtering target, and the like. It is preferable to be within the range of 50 atomic% and Al: 2 to 40 atomic%.
  • the following sputtering conditions are preferably used. Ultimate vacuum: about 1 ⁇ 10 ⁇ 5 torr or less, gas pressure: about 1 to 5 mtorr, Power density: about 1.0 to 8 W / cm 2 (standardized by the area of a 4 inch ⁇ target) Substrate temperature: room temperature to 300 ° C
  • an In—Cu alloy film (thickness: about 0.1 to 0.4 ⁇ m) is formed by sputtering. Film.
  • This process is a process characterizing the present invention, and a technique using an In—Cu alloy film has not been known so far for forming a solar cell light absorption layer by sputtering. According to the sputtering method, an alloy film having a composition almost corresponding to the composition of the target can be obtained with high reproducibility and mass production as compared with the vapor deposition method.
  • the In—Cu alloy film may be sputtered using an In—Cu alloy target, or may be sputtered by chip-on a Cu element metal to a pure In target.
  • the In—Cu alloy target used in the present invention is novel and will be described in detail later.
  • the content of Cu in the In—Cu alloy film is preferably 30 to 80 atomic%, whereby a desired continuous film can be obtained. If the amount of Cu is less than 30 atomic%, the degree of island-like deposition tends to be improved as compared with a pure In film, but there is a possibility that a clear continuous film region cannot be obtained. From the viewpoint of making the region covering the lower Cu—Ga alloy film as wide as possible, the Cu content is preferably 30 atomic%.
  • ⁇ Cu / In order to satisfy the condition that the ratio of (In + Ga) ⁇ is approximately 0.85 to 0.99 and the ratio of ⁇ Ga / (In + Ga) ⁇ is approximately 0.1 to 0.3,
  • the upper limit is preferably about 80 atomic%.
  • a more preferable amount of Cu is 40 to 70 atomic%, and further preferably 45 to 60 atomic%.
  • the following sputtering conditions are preferably used. Ultimate vacuum: about 1 ⁇ 10 ⁇ 5 torr or less, gas pressure: about 1 to 5 mtorr, Power density: about 0.5 to 5 W / cm 2 (standardized by the area of a 4 inch ⁇ target) Substrate temperature: room temperature to 300 ° C
  • the In—Cu target used for forming the In—Cu alloy film is novel, and the preferable content of Cu in the target is 30 to 80 atomic%, and the balance is In and inevitable impurities.
  • inevitable impurities include Fe (0.03% by weight or less), Si (0.03% by weight or less), C (0.02% by weight or less), and O (0.01% by weight or less).
  • the composition of the precursor before selenization can be adjusted to obtain a desired composition of the light absorption layer by the first and second steps.
  • the composition of the precursor before selenization and the light absorption layer after selenization do not coincide with each other because the low melting point InSe evaporates during selenization (that is, the amount of In changes before and after selenization). Therefore, the composition of the precursor is an estimated design that allows for these evaporation components.
  • the structure of the precursor is a laminate of a Cu—Ga alloy film or a Cu—Al alloy film and an In—Cu alloy film in order from the substrate side.
  • a Cu—Ga alloy film or a Cu—Al alloy film and an In—Cu alloy film it is preferable to continuously form a Cu—Ga alloy film or a Cu—Al alloy film and an In—Cu alloy film.
  • a combination of a plurality of stacking orders can be considered.
  • a Cu—Ga alloy film or a Cu—Al alloy is used in order to realize a layer-by-layer reaction.
  • an In—Cu alloy film having a continuous film region is continuously formed on the alloy film.
  • a Cu—Ga alloy film or a Cu—Al alloy film and an In—Cu alloy film adjacent to each other can be obtained.
  • “adjacent” refers to an aspect in which a Cu—Ga alloy film or a Cu—Al alloy film and an In—Cu alloy film are laminated immediately above or below.
  • the precursor is composed of a Cu—Ga alloy film or a Cu—Al alloy film, an In—Cu alloy film, and a pure In film in order from the substrate side. It becomes a laminate.
  • the third step is an optional step provided as necessary, and a pure In film is formed by sputtering in order to obtain a precursor having a predetermined composition by complementing the insufficient amount of In.
  • the island-like In film is formed on the In—Cu alloy film (continuous film) by the formation of the pure In film. Since the island-like In film is formed on the continuous film, light absorption is achieved. It is presumed that there are few adverse effects (such as a decrease in photoelectric conversion efficiency) on the performance of the layer.
  • the thickness of the pure In film varies depending on the amount of Cu in the In—Cu film in the second step described above, but is preferably controlled within the range of 0.02 to 1.0 ⁇ m.
  • a sputtering condition a sputtering condition of a pure In film usually used in the field can be adopted.
  • the following conditions are preferably used. Ultimate vacuum: about 1 ⁇ 10 ⁇ 5 torr or less, gas pressure: about 1 to 5 mtorr, Power density: about 0.5 to 3 W / cm 2 (standardized by the area of a 4 inch ⁇ target)
  • Substrate temperature room temperature to 300 ° C
  • the step before the first step (the step of forming a back electrode such as Mo on the substrate) and the selenization step after forming the precursor are not particularly limited, and a method usually used in the technical field is adopted. It is possible to refer to the methods described in Patent Documents 1 and 2 described above.
  • the selenization process is roughly classified into a gas phase method using H 2 and / or H 2 S, a solid phase method not using H 2 , and a method using sputtering and annealing using an In—Se alloy target. Any method may be employed in the invention.
  • substrate used is not specifically limited, for example, besides a soda-lime glass (SLG) shown in FIG. 1, a low alkali glass board
  • SLG soda-lime glass
  • substrate metal base materials, such as stainless steel and titanium, or a resin base material etc. are used.
  • the above embodiment is a preferred example of the present invention, and the present invention is not intended to be limited to this.
  • the manufacturing process of a light absorption layer for a solar cell (strictly including the step of forming an In—Cu alloy film by sputtering) All of the precursor film formation step before selenization is included in the scope of the present invention.
  • the obtained light absorption layer is not CIGS but CIAS.
  • Al like Ga, improves the band gap and has the effect of improving the light absorption efficiency of sunlight. Therefore, Al is widely used as a constituent atom of the light absorption layer.
  • the method for forming the Cu—Al alloy film by sputtering is basically the same as the method for forming the Cu—Ga alloy film described above.
  • an In—Cu alloy film is formed on a back electrode such as Mo by sputtering
  • a Cu—Ga alloy film is formed by sputtering
  • an In—Cu alloy film is further formed.
  • a precursor having a predetermined composition can also be obtained by forming a film by sputtering and forming a pure In film as necessary (Modification 1).
  • the structure of the precursor obtained by this method is a sandwich structure in which an In—Cu alloy film (continuous film) is provided before and after (upper and lower) of a Cu—Ga alloy film, and the above method has a particularly high amount of Cu (for example, This is an effective method for forming an In—Cu alloy film having a Cu content of about 60 to 80 atoms. That is, the predetermined thickness is not secured by one In—Cu alloy film as in the above-described embodiment, but the film thickness is distributed by interposing two In—Cu alloy films as in Modification 1 above.
  • the Ga concentration profile in the precursor can be controlled, the Ga concentration on the interface side with the buffer layer such as CdS formed on the light absorption layer is increased, and the band gap is widened, resulting in photoelectric conversion. A highly efficient light absorption layer can be obtained.
  • an In—Cu alloy film is first formed on a back electrode such as Mo by sputtering, and then a Cu—Ga alloy film is formed by sputtering, and a pure In film is formed as necessary.
  • a precursor having a composition can also be obtained (Modification 2).
  • the structure of the precursor obtained by this method is an In—Cu alloy film and a Cu—Ga alloy film (if necessary, a pure In film) in this order from the substrate side.
  • an In—Cu alloy film continuous film is formed on Mo, so that the Ga concentration profile in the precursor can be controlled and formed on the light absorption layer.
  • the Ga concentration on the interface side with the buffer layer such as CdS becomes high and the band gap is widened. As a result, a light absorption layer with high photoelectric conversion efficiency can be obtained.
  • the light absorption layer for a solar cell obtained by the above method contains Cu; at least one element selected from the group consisting of In, Ga, and Al; and Se. Specifically, a CIGS light absorption layer containing Ga, a CIAS light absorption layer containing Al, a CIS light absorption layer containing no Ga or Al, and the like are typically exemplified.
  • Example 1 it is confirmed that a continuous film can be obtained by controlling the amount of Cu in the In—Cu alloy film within a preferable range.
  • Cu of the composition and thickness shown in Table 1 using various Cu—Ga alloy targets having different Ga contents on a low Na glass substrate manufactured by TechnoQuartz Co., Ltd., thickness: 0.7 mm.
  • a -Ga alloy film was formed (first step).
  • the sputtering conditions are as follows. Ultimate vacuum: 7 ⁇ 10 ⁇ 6 torr or less, gas pressure: 2 mtorr, Power density: 1.9 W / cm 2 (standardized by the area of a 4-inch ⁇ target) Substrate temperature: room temperature
  • sputtering using a pure In target or sputtering with a Cu chip chip-on the pure In target is performed on the Cu—Ga alloy film, and a pure In film or In— having the composition and thickness shown in Table 1 is performed.
  • a Cu alloy was laminated to obtain a precursor before selenization (second step).
  • the sputtering conditions are as follows. Ultimate vacuum: 7 ⁇ 10 ⁇ 6 torr or less, gas pressure: 2 mtorr, Power density: 0.6 W / cm 2 (standardized by the area of a 4-inch ⁇ target) Substrate temperature: room temperature
  • the cross section in the film thickness direction of each precursor thus obtained was observed by SEM (magnification 3000 times) and evaluated whether or not a continuous film region was formed on the Cu—Ga alloy film according to the following criteria. did. That is, the thickness of the pure In film or the Cu—In alloy film is calculated by converting the film into a film equivalent to a flattened film (in the case where a continuous film is not formed, such as pure In, chemical analysis is used. When the film thickness is converted into a flat film having the same volume as the island-like deposit, the area where the continuous film can be obtained is 80% or more with respect to the film thickness.
  • ⁇ the case of 20% or more and less than 30% is ⁇
  • the case of 10% or more and less than 20% is ⁇
  • the case of less than 10% is ⁇ .
  • ⁇ , ⁇ , ⁇ , and ⁇ were evaluated as acceptable (with continuous film formation).
  • Example 2 In this example, by performing the first and second steps; or by performing the third step depending on the amount of Cu in the In—Cu alloy film formed by the second step, the composition of the precursor is increased. It confirms that it can adjust to the range corresponding to the composition of the light absorption layer which can implement
  • No. 6 to 8 are examples in which the desired precursor composition was realized by performing the first and second steps (without the third step).
  • Examples 1 to 5 and 9 are examples in which a desired precursor composition is realized by performing the first to third steps.
  • the amount of Cu in the In—Cu alloy film formed in the second step is generally as high as 40 atomic% or more, and the thickness of the alloy film is approximately 100 to 500 nm.
  • the target is small, it is effective to perform the third step of forming a pure In film, whereby a precursor having a desired composition can be obtained.
  • No. 10 is an example in which the In—Cu alloy film used in the present invention is not used, and is a comparative example based on the judgment that it is not practical in consideration of productivity.
  • a precursor of a desired composition was secured by forming a pure Cu film (thickness 100 nm) in the second step and forming a pure In film (thickness 300 nm) in the third step. Therefore, it is necessary to form pure In as thick as 300 nm in the third step, and there is a high risk of deformation of the pure In target due to an increase in film formation time, which is not preferable from the viewpoint of productivity.
  • a pure In film is not formed as in the prior art, but an In—Cu alloy film is used.
  • a continuous In—Cu alloy film can be obtained instead of the In film.
  • a light-absorbing layer having a uniform composition within the same plane and good film quality ie, excellent in-plane uniformity
  • the provision of an absorption layer is highly expected.
  • the subsequent selenization step is performed by a surface-to-surface reaction (layer-by-layer), so that the in-plane uniformity is further improved.

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Abstract

L'invention fournit un procédé de fabrication de couche d'absorption de lumière pour cellule solaire à film mince conducteur composé permettant d'empêcher la formation d'une couche discontinue lors de la formation d'un film In pure par un procédé de pulvérisation, et permettant de réguler l'oxydation de Ga lors de la fabrication par exemple d'une couche d'absorption de lumière à base de CIGS contenant de préférence un Ga. Plus précisément, l'invention concerne un procédé de fabrication de couche d'absorption de lumière pour cellule solaire à film mince semi-conducteur composé contenant un Cu, un In, au moins un élément parmi un Ga et un Al, et un Se; et ce procédé comporte une étape de formation de film en alliage In-Cu par pulvérisation cathodique.
PCT/JP2011/072899 2010-10-05 2011-10-04 PROCÉDÉ DE FABRICATION DE COUCHE D'ABSORPTION DE LUMIÈRE POUR CELLULE SOLAIRE À FILM MINCE SEMI-CONDUCTEUR COMPOSÉ, ET CIBLE DE PULVÉRISATION CATHODIQUE D'ALLIAGE In-Cu WO2012046746A1 (fr)

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JP2017106091A (ja) * 2015-12-11 2017-06-15 Ｊｘ金属株式会社 Ｉｎ−Ｃｕ合金スパッタリングターゲット及びその製造方法

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US8703524B1 (en) * 2012-11-29 2014-04-22 Tsmc Solar Ltd. Indium sputtering method and materials for chalcopyrite-based material usable as solar cell absorber layers
AT13564U1 (de) 2013-01-31 2014-03-15 Plansee Se CU-GA-IN-NA Target
JP6798852B2 (ja) 2015-10-26 2020-12-09 三菱マテリアル株式会社 スパッタリングターゲット及びスパッタリングターゲットの製造方法

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