WO2012046746A1 - METHOD FOR MANUFACTURING LIGHT ABSORBING LAYER FOR COMPOUND SEMICONDUCTOR THIN-FILM SOLAR CELL AND In-Cu ALLOY SPUTTERING TARGET - Google Patents

METHOD FOR MANUFACTURING LIGHT ABSORBING LAYER FOR COMPOUND SEMICONDUCTOR THIN-FILM SOLAR CELL AND In-Cu ALLOY SPUTTERING TARGET 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
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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
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    • 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
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    • 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
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    • 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
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    • 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
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    • 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 at least one potential-jump barrier or surface barrier
    • 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 at least one potential-jump barrier or surface barrier 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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction solar cells
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    • 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
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    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

To provide a method for manufacturing a light absorbing layer for a compound semiconductor thin-film solar cell that can prevent discontinuous layer formation (formation of In film with island shapes) when a pure In film is formed by sputtering and that is capable of controlling Ga oxidation when a CIGS light absorbing layer and the like that preferably contain Ga are manufactured. The present invention relates to a method for manufacturing a light absorbing layer for a compound semiconductor thin-film solar cell that contains Cu; In; at least one element of Ga and Al; and Se, and that includes a step for forming an In-Cu alloyed film by sputtering.

Description

化合物半導体薄膜太陽電池用光吸収層の製造方法、およびＩｎ－Ｃｕ合金スパッタリングターゲットMethod for producing light absorbing layer for compound semiconductor thin film solar cell, and In-Cu alloy sputtering target
　本発明は、Ｃｕと；Ｉｎ、Ｇａ、およびＡｌよりなる群から選択される少なくとも一種の元素と；Ｓｅを含む化合物半導体薄膜を光吸収層として用いる太陽電池用光吸収層の製造方法、および上記方法に用いられるＩｎ－Ｃｕ合金スパッタリングターゲットに関するものである。 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.
　Ｃｕと；Ｉｎ、Ｇａ、Ａｌの１３族元素（長周期型周期表に基づく）と；Ｓｅとを含む化合物半導体薄膜は、太陽電池の光吸収層として汎用されており、代表的にはＣＩＳ（Ｃｕ＋Ｉｎ＋Ｓｅ）系またはＣＩＧＳ（Ｃｕ＋Ｉｎ＋Ｇａ＋Ｓｅ）系の光吸収層が挙げられる。Ｇａを含むＣＩＧＳ系の光吸収層はＣＩＳに比べてバンドギャップがやや大きくなり、太陽光の変換効率が向上することが知られている。 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.
　図１に、ＣＩＧＳ系化合物半導体薄膜を光吸収層に用いた太陽電池の構成の一例を示す。図１に示すＣＩＧＳ系薄膜陽電池は、ソーダーライムガラス（ＳＬＧ）基板上に、Ｍｏ裏面電極、ＣＩＧＳ系薄膜の光吸収層、ＣｄＳのバッファー層、ＺｎＯ薄膜の窓層、ＩＴＯ薄膜の透明電極層、ＡｌまたはＮｉＣｒの電極から構成されている。上記光吸収層の形成方法は、大別して蒸着法、スパッタリング法、塗布法の３種類の方法が提案されている。このうちスパッタリング法は、液晶ディスプレイなどの用途において１ｍ角以上の大型基板での量産実績があり、他の方法に比べて大面積の成膜が容易であるなどの理由により、日本国内では既に量産が開始されている。 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. Among them, 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.
　スパッタリング法では通常、Ｃｕ（１１族元素）とＧａ（１３族元素）からなるＣｕ－Ｇａ合金ターゲットおよび純Ｉｎターゲットを用いてＣｕ－Ｇａ合金膜および純Ｉｎ膜を基板上に順次積層した後、Ｓｅを含む雰囲気下にて約５００～５５０℃前後の熱処理工程（セレン化と呼ばれる。）を施すことによってＣＩＧＳ系光吸収層を製造している。セレン化前の前駆体薄膜は通常、プリカーサーと呼ばれている。上記方法によれば、Ｃｕ－Ｇａ合金膜および純Ｉｎ膜の積層体からなるプリカーサーが得られる。 In the sputtering method, usually, 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.
　スパッタリング法を用いてＣＩＧＳ系光吸収層のプリカーサーを作製する方法として、特許文献１および特許文献２が挙げられる。このうち特許文献１は、「スパッタリング法によって作製したＣＩＧＳ膜ではＧａが表面側に偏析し、膜厚方向におけるＧａ分布が不均一になって良好な電池特性が得られない」などの問題を解決するため、基板側から順に、下記（Ｉ）～（ＩＩＩ）の三つの実施形態を開示している。
　（Ｉ）第１の実施形態として、Ｉｎ薄膜またはＣｕ薄膜を成膜する第１の工程と、Ｃｕ－Ｇａ合金薄膜を成膜する第２の工程と、Ｃｕ薄膜を成膜する第３の工程と、を有する製造方法；
　（ＩＩ）第２の実施形態として、Ｉｎ薄膜またはＣｕ薄膜を成膜する第１の工程と、Ｃｕ－Ｇａ合金薄膜を成膜する第２の工程と、Ｉｎ薄膜を成膜する第３の工程と、を有する製造方法；
　（ＩＩＩ）第３の実施形態として、Ｃｕ－Ｇａ合金薄膜を成膜する第１の工程と、Ｉｎ薄膜またはＣｕ薄膜を成膜する第２の工程と、Ｃｕ－Ｇａ合金薄膜を成膜する第３の工程と、を有する製造方法。 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.
(I) As a first 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 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:
　また特許文献２では、「スパッタリングによってＩｎ層を形成する際、低融点で表面張力が大きいというＩｎの物性に起因してＩｎの結晶が比較的低温で粒状に成長し、隙間を有する粗なＩｎ膜（島状Ｉｎ膜）が表面に生成してしまうが、その後のセレン化時に当該隙間に対応する箇所がＣｕリッチとなって低抵抗のＣｕ－Ｓｅ化合物が局所的に生成され、電池特性が劣化する」という問題を解決するため、酸素を添加したスパッタガス雰囲気下でＩｎ層を形成する方法を開示している。 Further, in 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. In order to solve the problem of “deteriorating”, a method of forming an In layer in a sputtering gas atmosphere to which oxygen is added is disclosed.
日本国特許第４０５６７０２号公報Japanese Patent No. 4056702 日本国特開２００３－２５８２８２号公報Japanese Unexamined Patent Publication No. 2003-258282
　しかしながら、前述した特許文献１のように純Ｉｎ膜の成膜工程を包含する方法では、以下の問題を抱えている。 However, the method including the process of forming a pure In film as in Patent Document 1 described above has the following problems.
　すなわち前述した特許文献２にも記載されているように、純Ｉｎ膜をスパッタリング法で形成するとＩｎ結晶が島状に堆積して不連続層が形成されるようになり、例えばＣｕ－Ｇａ合金膜上に純Ｉｎ膜を積層すると、純Ｉｎで覆われる部分と覆われない部分が形成されるようになる。このようなＩｎの島状堆積物の形成は、結果的に太陽電池の性能低下をもたらす。上記島状堆積の形成を防止するため、純Ａｌでは、所望の膜厚を得るための成膜時間を複数回に分割して成膜することにより成膜時の実効的な基板温度上昇を抑制し、島状堆積を改善させる方法などが提案されているが、純Ｉｎは融点が約１５６℃と低融点のため、上記方法によっても連続膜を得ることは困難である。 That is, as described in Patent Document 2 described above, when a pure In film is formed by a sputtering method, an In crystal is deposited in an island shape to form a discontinuous layer. For example, a Cu—Ga alloy film When a pure In film is laminated thereon, a portion covered with pure In and a portion not covered are formed. The formation of such In island deposits results in degradation of the performance of the solar cell. In order to prevent the formation of the above island-like deposits, pure Al suppresses the effective substrate temperature rise during film formation by dividing the film formation time for obtaining a desired film thickness into a plurality of times. Although a method for improving island deposition has been proposed, pure In has a low melting point of about 156 ° C., and it is difficult to obtain a continuous film even by the above method.
　また、Ｇａも約２９．８℃と非常に低融点であり、上記のように島状Ｉｎ結晶が堆積する状況下では、セレン化前のプリカーサー形成時点においてＧａ酸化物やＣｕＧａ酸化物などの酸化物が最表面に容易に形成されるため、セレン化後のＣＩＧＳ系薄膜の膜質均一性が劣化し、再現性も劣るなどの弊害を招く。 Also, 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.
　また量産性を考慮すると、純Ｉｎターゲットを用いて純Ｉｎ膜を成膜する場合、成膜が進むにつれ、ターゲット－基板間距離も変化して実効的なターゲット表面温度や基板温度も変動するため、純Ｉｎ膜自体の膜厚制御や膜質の再現性確保が困難となる。また、純Ｉｎターゲットでは、連続成膜中の変形が大きく、また高パワー成膜が困難であり、結果的に生産性の向上実現は難しいという欠点がある。 In consideration of mass productivity, when a pure In film is formed using a pure In target, as the deposition proceeds, 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. In addition, 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.
　一方、前述した特許文献２のように酸素添加ガス雰囲気下で純Ｉｎ膜を成膜する方法では、セレン化後のＣＩＧＳ薄膜に酸素が残存し、膜質が低下するようになる。 On the other hand, in the method of forming a pure In film in an oxygen-added gas atmosphere as in Patent Document 2 described above, oxygen remains in the CIGS thin film after selenization, and the film quality deteriorates.
　本発明は上記事情に鑑みてなされたものであり、その目的は、スパッタリング法によって純Ｉｎ膜を成膜したときにおける不連続層生成（島状Ｉｎ膜の形成）を防止でき、好ましくはＧａを含むＣＩＧＳ系光吸収層などを製造する場合には、Ｇａの酸化を抑制することが可能な化合物薄膜太陽電池用光吸収層の製造方法、および当該光吸収層の形成に好適に用いられるスパッタリングターゲットを提供することにある。 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. When manufacturing CIGS type light absorption layer etc. which contain, 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.
　本発明は、以下の化合物半導体薄膜太陽電池用光吸収層の製造方法およびＩｎ－Ｃｕ合金スパッタリングターゲットを提供する。
　（１） Ｃｕと；Ｉｎと；ＧａおよびＡｌのうち少なくとも一種の元素と；Ｓｅを含む化合物半導体薄膜太陽電池用光吸収層の製造方法であって、
  スパッタリングによってＩｎ－Ｃｕ合金膜を成膜する工程を含むことを特徴とする化合物半導体薄膜太陽電池用光吸収層の製造方法。 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.
(1) 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.
　（２） スパッタリングによってＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜を成膜する第一の工程と、
  スパッタリングによってＩｎ－Ｃｕ合金膜を成膜する第二の工程と、  
を順次含むものである（１）に記載の製造方法。
　（３）　第二の工程の後に、スパッタリングによって純Ｉｎ膜を成膜する第三の工程を含む（２）に記載の製造方法。 (2) 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;
The manufacturing method as described in (1) which contains these one by one.
(3) The manufacturing method according to (2), including a third step of forming a pure In film by sputtering after the second step.
　（４）  前記Ｉｎ－Ｃｕ合金膜におけるＣｕの含有量は３０～８０原子％である（１）～（３）のいずれか一つに記載の製造方法。 (4) The manufacturing method according to any one of (1) to (3), wherein the content of Cu in the In—Cu alloy film is 30 to 80 atomic%.
　（５）  前記Ｃｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜と、前記Ｉｎ－Ｃｕ合金膜を連続して形成するものである（１）～（３）のいずれか一つに記載の製造方法。 (5) The manufacturing method according to any one of (1) to (3), wherein the Cu—Ga alloy film or Cu—Al alloy film and the In—Cu alloy film are continuously formed.
　（６）  Ｃｕと；Ｉｎと；ＧａおよびＡｌのうち少なくとも一種の元素と；Ｓｅを含む化合物半導体薄膜太陽電池用光吸収層の製造に用いられるＩｎ－Ｃｕ合金スパッタリングターゲットであって、
  Ｃｕを３０～８０原子％含有し、残部：Ｉｎおよび不可避不純物であることを特徴とするＩｎ－Ｃｕ合金スパッタリングターゲット。 (6) 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.
　本発明によれば、スパッタリング法によって太陽電池用光吸収層を製造するに当たり、従来のように純Ｉｎ膜を成膜するのではなくＩｎ－Ｃｕ合金膜を用いて製造しているため、島状Ｉｎ膜ではなく連続したＩｎ－Ｃｕ合金膜が得られる。その結果、同一面内での組成が均一で膜質の良好な（すなわち、面内均一性に優れた）光吸収層を、高い生産性で再現性良く成膜できるため、光電変換効率が高い光吸収層の提供が大いに期待される。例えばＣＩＧＳ系光吸収層の製造に当たり、Ｃｕ－Ｇａ合金膜を成膜した後にＩｎ－Ｃｕ合金膜の連続層を成膜すると、ＣｕＧａ膜の露出が防止されるため、大気輸送中などにおけるＧａの酸化を抑制できるほか、その後のセレン化工程が、面と面との反応（ｌａｙｅｒ－ｂｙ－ｌａｙｅｒ）で行なわれるようになるため、面内均一性が一層向上するようになる。 According to the present invention, when manufacturing a light absorption layer for solar cells by sputtering, 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. As a result, a light-absorbing layer having a uniform composition within the same plane and good film quality (ie, excellent in-plane uniformity) can be formed with high productivity and reproducibility. The provision of an absorption layer is highly expected. For example, when manufacturing a CIGS-based light absorption layer, if a continuous layer of In—Cu alloy film is formed after forming a Cu—Ga alloy film, the exposure of the CuGa film is prevented, so that the Ga In addition to being able to suppress oxidation, the subsequent selenization step is performed by a surface-to-surface reaction (layer-by-layer), so that the in-plane uniformity is further improved.
図１は、ＣＩＧＳ系化合物半導体薄膜を光吸収層に用いた代表的な太陽電池の構成を模式的に示す断面図である。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. 図２は、Ｃｕ－Ｇａ合金膜の上にスパッタリング法によって純Ｉｎ膜を成膜したときにおける薄膜の状態を示すＳＥＭ写真である。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. 図３は、Ｃｕ－Ｇａ合金膜の上にスパッタリング法によってＩｎ－Ｃｕ合金膜（Ｃｕ量≒３５原子％）を成膜したときにおける薄膜の状態を示すＳＥＭ写真である。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. 図４は、Ｃｕ－Ｇａ合金膜の上にスパッタリング法によってＩｎ－Ｃｕ合金膜（Ｃｕ量≒５５原子％）を成膜したときにおける薄膜の状態を示すＳＥＭ写真である。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. 図５は、Ｃｕ－Ｇａ合金膜の上にスパッタリング法によってＩｎ－Ｃｕ合金膜（Ｃｕ量≒６０原子％）を成膜したときにおける薄膜の状態を示すＳＥＭ写真である。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.
　本発明者らは、ＣＩＧＳ系薄膜などに代表されるＣｕと；Ｉｎ、Ｇａ、およびＡｌよりなる群から選択される少なくとも一種の元素と；Ｓｅを含む化合物半導体薄膜を光吸収層として用いる太陽電池用光吸収層（厳密には、セレン化前のプリカーサー）をスパッタリング法によって成膜するに当たり、純Ｉｎ膜をスパッタリングによって成膜するときの問題点（島状Ｉｎ膜の形成による不連続層の形成、後記する図２を参照）を解決するため、検討を重ねてきた。その結果、従来のように純Ｉｎ膜を成膜するのではなくＩｎ－Ｃｕ合金膜をスパッタリング法によって成膜する工程を含む製造方法を用いれば、連続したＩｎ－Ｃｕ合金膜が形成されることを見出し、本発明を完成した。 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) In order to solve the problem described in FIG. As a result, 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.
　スパッタリング法によるＩｎ－Ｃｕ合金膜の形成によって、後記する図３～図５に示すように連続したＩｎ－Ｃｕ合金膜が得られる理由は詳細には不明であるが、上記合金膜の成膜時にＩｎ－Ｃｕの金属間化合物が核生成サイトとして有効に働くためではないかと推察される。 The reason why a continuous In—Cu alloy film can be obtained as shown in FIGS. 3 to 5 to be described later by forming an In—Cu alloy film by sputtering is not clear in detail. It is presumed that the intermetallic compound of In—Cu works effectively as a nucleation site.
　図２～図５は、Ｃｕ－Ｇａ合金膜の上にスパッタリング法によって純Ｉｎ膜またはＩｎ－Ｃｕ合金膜を成膜するにあたり、上記Ｉｎ－Ｃｕ合金膜中に含まれるＣｕの含有量を変化させたときにおける当該合金膜の最表面の状態をＳＥＭ（倍率：３０００倍）で分析した結果を示すＳＥＭ写真である。 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).
　図２は、Ｃｕ量が０、すなわち純Ｉｎ膜をＣｕ－Ｇａ合金膜上に成膜したときの様子を示す図であり、連続した層ではなく島状のＩｎ膜が形成されていることが分かる。 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.
　これに対し、図３～図５は、本発明に用いられるＩｎ－Ｃｕ合金膜を成膜した例であり、図３はＣｕ量≒３５原子％、図４はＣｕ量≒５５原子％、図５はＣｕ量≒６０原子％を含むＩｎ－Ｃｕ合金膜をＣｕ－Ｇａ合金膜上に成膜したときの様子を示すものである。図３～図５に示すようにいずれのＩｎ－Ｃｕ合金膜も、連続した膜が生成されることが分かる。これにより、Ｃｕ－Ｇａ膜の露出が防止されるため、大気輸送中などにおけるＧａの酸化を抑制できるほか、その後のセレン化工程が、面と面との反応（ｌａｙｅｒ－ｂｙ－ｌａｙｅｒ）で行なわれるようになるため、面内均一性が一層向上するようになる。また、Ｃｕ含有量によって当該Ｉｎ－Ｃｕ合金膜の表面性状は変化し得、Ｃｕ量が多くなる程（図３→図４→図５）、最表面に存在する島状Ｉｎ領域（凹凸形状）は小さくなって凹凸の少ない平坦な連続膜が得られることが分かる。この島状Ｉｎ領域はＩｎ－Ｃｕ合金膜（連続膜）の上に形成されており、しかも後記するように本発明ではＩｎ－Ｃｕ合金膜中の好ましいＣｕ量が適切に制御されているため、上記島状Ｉｎ領域の形成による太陽電池の性能低下の恐れはないと推察される。また、凹凸の少ない平坦な連続層が形成されることにより、前述した連続膜形成による効果が一層促進されると推察される。 On the other hand, 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%, No. 5 shows a state when an In—Cu alloy film containing Cu content = 60 atomic% is formed on the Cu—Ga alloy film. As shown in FIGS. 3 to 5, it can be seen that 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. Further, 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.
　後記するように本発明では、所望の連続膜を形成し得、且つ、光電変換効率の高い太陽電池用光吸収層の形成が実現可能なように、Ｉｎ－Ｃｕ合金膜に含まれるＣｕ量を、好ましくはおおむね３０～８０原子％の範囲内に制御しているが、上記の図３～図５より、Ｃｕ量が上記範囲内であれば、所望とするＩｎ－Ｃｕ合金の連続膜（好ましくは、表面が一層平坦化された連続膜）が得られることが分かる。 As will be described later, in the present invention, 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. However, 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.
　上述したように本発明に係る太陽電池用光吸収層の製造方法は、スパッタリングによってＩｎ－Ｃｕ合金膜を成膜する工程を含んでいるところに特徴がある。具体的には、所望とする光吸収層（Ｃｕと；Ｉｎ、Ｇａ、およびＡｌよりなる群から選択される少なくとも一種の元素と；Ｓｅを含む化合物半導体薄膜の光吸収層）が得られるように、製造工程中に少なくともＩｎ－Ｃｕ合金膜をスパッタリング法によって成膜する工程を含んでいれば良く、代表的には、下記工程を含む実施形態が挙げられる：
　スパッタリングによってＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜を成膜する第一の工程と、スパッタリングによってＩｎ－Ｃｕ合金膜を成膜する第二の工程と、必要に応じてスパッタリングによって純Ｉｎ膜を成膜する第三の工程と、を順次含む方法。 As described above, 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. In addition, it suffices that 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.
　以下、上記実施形態における第一～第三の各工程を詳しく説明するが、本発明はこれに限定する趣旨ではない。 Hereinafter, the first to third steps in the above embodiment will be described in detail, but the present invention is not limited to this.
　（第一の工程）
　第一の工程では、Ｍｏなどの裏面電極上に、スパッタリングによってＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜（厚さ：約０．０５～１．０μｍ）を成膜する。この成膜工程は公知であり、通常用いられるＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜の成膜方法を適宜採用することができる。例えば前述した特許文献１や２の方法を参照することもできる。上記工程に用いられるスパッタリングターゲット（以下、ターゲットと略記する場合がある。）としては代表的にはＣｕ－Ｇａ合金ターゲットまたはＣｕ－Ａｌ合金ターゲットが挙げられ、当該合金ターゲットの組成を調整することによってＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜の組成を調整でき、最終的に、光電変換効率の高い組成の光吸収層を実現することができる。あるいは、純ＣｕターゲットにＧａ元素またはＡｌ元素の金属をチップオンすることによってＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜の組成を調整しても良い。Ｃｕ－Ｇａ合金膜におけるＧａまたはＡｌの好ましい含有量は、所望とする光吸収層の組成や、合金スパッタリングターゲット製造の容易さなどに応じて適宜適切に設定され得るが、おおむね、Ｇａ：１０～５０原子％、Ａｌ：２～４０原子％の範囲内であることが好ましい。 (First step)
In the first step, a Cu—Ga alloy film or a Cu—Al alloy film (thickness: about 0.05 to 1.0 μm) 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. For example, 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. 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. Alternatively, 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%.
　本発明では、例えば以下のスパッタリング条件が好ましく用いられる。
　到達真空度：約１×１０－５ｔｏｒｒ以下、ガス圧：約１～５ｍｔｏｒｒ、
　パワー密度：約１．０～８Ｗ／ｃｍ２（４インチφターゲットの面積で規格化）
　基板温度：室温～３００℃ In the present invention, for example, 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 φ target)
Substrate temperature: room temperature to 300 ° C
　（第二の工程）
　上記のようにしてＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜を成膜した後、第二の工程では、スパッタリングによってＩｎ－Ｃｕ合金膜（厚さ：約０．１～０．４μｍ）を成膜する。この工程は本発明を特徴付ける工程であり、太陽電池用光吸収層のスパッタリングによる成膜に当たってＩｎ－Ｃｕ合金膜を利用した技術はこれまで知られていない。スパッタリング法によれば、蒸着法などに比べて、ターゲットの組成にほぼ応じた組成の合金膜を再現性良く、しかも量産して得られる。 (Second step)
After forming the Cu—Ga alloy film or Cu—Al alloy film as described above, in the second step, an In—Cu alloy film (thickness: about 0.1 to 0.4 μm) 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.
　上記Ｉｎ－Ｃｕ合金膜は、Ｉｎ－Ｃｕ合金ターゲットを用いてスパッタリングしても良いし、あるいは、純ＩｎターゲットにＣｕ元素の金属をチップオンすることによってスパッタリングしても良い。本発明に用いられるＩｎ－Ｃｕ合金ターゲットは新規であり、詳細は後述する。 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.
　上記Ｉｎ－Ｃｕ合金膜におけるＣｕの含有量は３０～８０原子％であることが好ましく、これにより、所望とする連続膜が得られる。Ｃｕ量が３０原子％未満では、純Ｉｎ膜に比べて島状堆積の程度は改善傾向にあるものの、明瞭な連続膜の領域が得られないおそれがある。下層のＣｕ－Ｇａ合金膜を覆う領域をできるだけ広くするという観点から、Ｃｕの含有量は３０原子％であることが好ましい。Ｃｕ量が多くなる程、凹凸の少ない平坦なＩｎ－Ｃｕ合金膜が成膜される傾向にあるが、光電変換効率の高い光吸収層を得るために一般に採用される条件、すなわち、｛Ｃｕ／（Ｉｎ＋Ｇａ）｝の比がおおむね０．８５～０．９９程度であり、｛Ｇａ／（Ｉｎ＋Ｇａ）｝の比がおおむね０．１～０．３程度の条件を満足するためには、Ｃｕ量の上限をおおむね８０原子％とすることが好ましい。より好ましいＣｕ量は４０～７０原子％であり、更に好ましくは４５～６０原子％である。 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%. As the amount of Cu increases, a flat In—Cu alloy film with less unevenness tends to be formed, but the conditions generally employed for obtaining a light absorption layer with high photoelectric conversion efficiency, that is, {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%.
　本発明では、例えば以下のスパッタリング条件が好ましく用いられる。
　到達真空度：約１×１０－５ｔｏｒｒ以下、ガス圧：約１～５ｍｔｏｒｒ、
　パワー密度：約０．５～５Ｗ／ｃｍ２（４インチφターゲットの面積で規格化）
　基板温度：室温～３００℃ In the present invention, for example, 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 φ target)
Substrate temperature: room temperature to 300 ° C
　上述したようにＩｎ－Ｃｕ合金膜の成膜に用いられるＩｎ－Ｃｕターゲットは新規であり、当該ターゲットにおけるＣｕの好ましい含有量は３０～８０原子％であり、残部：Ｉｎおよび不可避的不純物である。不可避不純物としては、例えば、Ｆｅ（０．０３重量％以下）、Ｓｉ（０．０３重量％以下）、Ｃ（０．０２重量％以下）、Ｏ（０．０１重量％以下）が挙げられる。 As described above, 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. . Examples of 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).
　本発明では、上記第一および第二の工程によってセレン化前のプリカーサーの組成を、所望となる光吸収層の組成が得られるようなものに調整することができる。厳密には、セレン化前のプリカーサーとセレン化後の光吸収層とは、セレン化時に低融点のＩｎＳｅが蒸発するなどして組成が一致しない（すなわち、セレン化の前後でＩｎの量が変化する）ため、プリカーサーの組成は、これらの蒸発分を見込んだ見積設計となる。上記第一および第二の工程によって所望のプリカーサーを得る場合、当該プリカーサーの構成は、基板側から順にＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜と、Ｉｎ－Ｃｕ合金膜の積層体となる。 In the present invention, 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. Strictly speaking, 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. When a desired precursor is obtained by the first and second steps, 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.
　本発明では、Ｃｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜と、Ｉｎ－Ｃｕ合金膜を連続して形成することが好ましい。プリカーサーの組成調整の点では、複数の積層順の組み合わせが考えられるが、本発明では、面と面との反応（ｌａｙｅｒ－ｂｙ－ｌａｙｅｒ）を実現させるため、Ｃｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜に対し、好ましくは連続膜領域を有するＩｎ－Ｃｕ合金膜を連続して形成する。これにより、Ｃｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜と、Ｉｎ－Ｃｕ合金膜が隣接したものが得られる。ここで「隣接する」とは、Ｃｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜とＩｎ－Ｃｕ合金膜とが、直上もしくは直下に積層されている態様を指す。 In the present invention, it is preferable to continuously form a Cu—Ga alloy film or a Cu—Al alloy film and an In—Cu alloy film. In order to adjust the composition of the precursor, a combination of a plurality of stacking orders can be considered. However, in the present invention, a Cu—Ga alloy film or a Cu—Al alloy is used in order to realize a layer-by-layer reaction. Preferably, an In—Cu alloy film having a continuous film region is continuously formed on the alloy film. Thereby, a Cu—Ga alloy film or a Cu—Al alloy film and an In—Cu alloy film adjacent to each other can be obtained. Here, “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.
　ただし、Ｉｎ－Ｃｕ合金膜中のＣｕ量が多くなると、Ｉｎ量などが不足するために所望となる光吸収層の組成に対応したプリカーサーの組成を確保できない場合があり、この場合は、上記第二工程に引き続き、以下の第三工程を行なう。上記第一～第三の工程によって所望のプリカーサーを得る場合、当該プリカーサーの構成は、基板側から順にＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜と、Ｉｎ－Ｃｕ合金膜と、純Ｉｎ膜の積層体となる。 However, if the amount of Cu in the In—Cu alloy film increases, the amount of In may not be sufficient, so that a precursor composition corresponding to the desired composition of the light absorption layer may not be ensured. Following the two steps, the following third step is performed. When a desired precursor is obtained by the first to third steps, 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.
　（第三の工程）
　第三の工程は、必要に応じて設けられる任意工程であり、Ｉｎ量の不足分を補完して所定組成のプリカーサーを得るために、スパッタリングによって純Ｉｎ膜を成膜する。純Ｉｎ膜の成膜によって島状Ｉｎ膜がＩｎ－Ｃｕ合金膜（連続膜）の上に形成されるが、この島状Ｉｎ膜は、当該連続膜の上に形成されているため、光吸収層の性能に及ぼす悪影響（光電変換効率の低下など）は少ないと推察される。 (Third process)
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.
　上記純Ｉｎ膜の厚さは、前述した第二の工程におけるＩｎ－Ｃｕ膜中のＣｕ量などによっても相違するが、おおむね、０．０２～１．０μｍの範囲内に制御することが好ましい。スパッタリング条件は、当該分野で通常用いられる純Ｉｎ膜のスパッタリング条件を採用することができ、例えば、以下の条件が好ましく用いられる。
　到達真空度：約１×１０－５ｔｏｒｒ以下、ガス圧：約１～５ｍｔｏｒｒ、
　パワー密度：約０．５～３Ｗ／ｃｍ２（４インチφターゲットの面積で規格化）
　基板温度：室温～３００℃ 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 μm. As a sputtering condition, a sputtering condition of a pure In film usually used in the field can be adopted. For example, 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 φ target)
Substrate temperature: room temperature to 300 ° C
　以上、本発明に用いられる好適な実施形態を説明した。ここで、第一工程前の工程（基板上にＭｏなどの裏面電極を成膜する工程）や、プリカーサー形成後のセレン化工程は特に限定されず、当該技術分野で通常用いられる方法を採用することができ、前述した特許文献１や２に記載の方法を参照しても良い。例えばセレン化工程は、Ｈ２および／またはＨ２Ｓを用いる気相法、Ｈ２を用いない固相法、Ｉｎ－Ｓｅ合金ターゲットを用いたスパッタリングおよびアニールによる方法に大別されるが、本発明ではいずれの方法も採用することができる。また、用いられる基板の種類も特に限定されず、例えば図１に示すソーダライムガラス（ＳＬＧ）のほか、低アルカリガラス基板、ステンレスやチタンなど金属基材あるいは樹脂基材なども用いられる。 The preferred embodiments used in the present invention have been described above. Here, 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. For example, 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. Moreover, the kind of board | substrate used is not specifically limited, For example, besides a soda-lime glass (SLG) shown in FIG. 1, a low alkali glass board | substrate, metal base materials, such as stainless steel and titanium, or a resin base material etc. are used.
　なお、上記の実施形態は本発明の好ましい一例であり、本発明はこれに限定する趣旨ではなく、スパッタリングによるＩｎ－Ｃｕ合金膜の成膜工程を含む太陽電池用光吸収層の製造工程（厳密には、セレン化前のプリカーサーの成膜工程）はすべて、本発明の範囲内に含まれる。 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.
　例えば上記実施形態において、Ｃｕ－Ｇａ合金膜の代わりにＣｕ－Ａｌ合金膜を用いた場合、得られる光吸収層はＣＩＧＳではなくＣＩＡＳとなる。ＡｌもＧａと同様、バンドギャップを向上させて太陽光の光吸収効率向上効果を有するため、光吸収層の構成原子として広く用いられている。スパッタリングによってＣｕ－Ａｌ合金膜を成膜する方法は、前述したＣｕ－Ｇａ合金膜を成膜する方法と基本的に同じである。 For example, in the above embodiment, when a Cu—Al alloy film is used instead of the Cu—Ga alloy film, 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.
　あるいは、上記実施形態以外の改変例として、Ｍｏなどの裏面電極上にＩｎ－Ｃｕ合金膜をスパッタリングによって成膜した後、Ｃｕ－Ｇａ合金膜をスパッタリングによって成膜し、更にＩｎ－Ｃｕ合金膜をスパッタリングによって成膜し、必要に応じて純Ｉｎ膜を成膜することによって所定組成のプリカーサーを得ることもできる（改変例１）。この方法によって得られるプリカーサーの構成は、Ｃｕ－Ｇａ合金膜の前後（上下）にＩｎ－Ｃｕ合金膜（連続膜）を設けたサンドイッチ構成であり、上記方法は、特にＣｕ量がおおむね高い（例えばＣｕ量が約６０～８０原子）Ｉｎ－Ｃｕ合金膜を成膜する場合に有効な方法である。すなわち、前述した実施形態のように一つのＩｎ－Ｃｕ合金膜で所定厚さを確保するのではなく、上記改変例１のように二つのＩｎ－Ｃｕ合金膜を介在させて膜厚を配分する方法を採用すれば、プリカーサー中のＧａ濃度プロファイルを制御でき、光吸収層の上に形成されるＣｄＳなどのバッファー層との界面側のＧａ濃度が高くなりバンドギャップが広がり、結果的に光電変換効率の高い光吸収層が得られるようになる。 Alternatively, as a modified example other than the above embodiment, after 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, and 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. If the method is adopted, 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.
　あるいは、Ｍｏなどの裏面電極上に、まずＩｎ－Ｃｕ合金膜をスパッタリングによって成膜した後、Ｃｕ－Ｇａ合金膜をスパッタリングによって成膜し、必要に応じて純Ｉｎ膜を成膜することによって所定組成のプリカーサーを得ることもできる（改変例２）。この方法によって得られるプリカーサーの構成は、基板側から順に、Ｉｎ－Ｃｕ合金膜およびＣｕ－Ｇａ合金膜（必要に応じて純Ｉｎ膜）である。この方法においても、上記改変例１と同様、Ｍｏ上にＩｎ－Ｃｕ合金膜（連続膜）が成膜されるため、プリカーサー中のＧａ濃度プロファイルを制御でき、光吸収層の上に形成されるＣｄＳなどのバッファー層との界面側のＧａ濃度が高くなりバンドギャップが広がり、結果的に光電変換効率の高い光吸収層が得られるようになる。 Alternatively, 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. Also in this method, as in Modification 1 above, 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.
　上記方法によって得られる太陽電池用光吸収層は、Ｃｕと；Ｉｎ、Ｇａ、およびＡｌよりなる群から選択される少なくとも一種の元素と；Ｓｅを含むものである。具体的には、Ｇａを含むＣＩＧＳ系光吸収層、Ａｌを含むＣＩＡＳ系光吸収層、ＧａやＡｌを含まないＣＩＳ系光吸収層などが代表的に例示される。 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.
　以下、実施例を挙げて本発明をより具体的に説明するが、本発明は下記実施例によって制限されず、前・後記の趣旨に適合し得る範囲で変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples, and can be implemented with modifications within a range that can meet the purpose described above and below. They are all included in the technical scope of the present invention.
　実施例１
　本実施例では、Ｉｎ－Ｃｕ合金膜中のＣｕ量を好ましい範囲に制御することによって、連続した膜が得られることを確認する。 Example 1
In this example, 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.
　詳細には、低Ｎａガラス基板（テクノクオーツ（株）製、厚さ：０．７ｍｍ）上に、Ｇａ量が異なる種々のＣｕ－Ｇａ合金ターゲットを用いて表１に示す組成および厚さのＣｕ－Ｇａ合金膜を成膜した（第一工程）。スパッタリング条件は以下のとおりである。
　到達真空度：７×１０－６ｔｏｒｒ以下、ガス圧：２ｍｔｏｒｒ、
　パワー密度：１．９Ｗ／ｃｍ２（４インチφターゲットの面積で規格化）
　基板温度：室温 In detail, 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 φ target)
Substrate temperature: room temperature
　次いで、上記Ｃｕ－Ｇａ合金膜の上に、純Ｉｎターゲットを用いたスパッタリング、または純ＩｎターゲットにＣｕチップをチップオンしたスパッタリングを行ない、表１に示す組成および厚さの純Ｉｎ膜またはＩｎ－Ｃｕ合金を積層してセレン化前のプリカーサーを得た（第二工程）。スパッタリング条件は以下のとおりである。
　到達真空度：７×１０－６ｔｏｒｒ以下、ガス圧：２ｍｔｏｒｒ、
　パワー密度：０．６Ｗ／ｃｍ２（４インチφターゲットの面積で規格化）
　基板温度：室温 Next, 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 φ target)
Substrate temperature: room temperature
　このようにして得られた各プリカーサーの膜厚方向断面について、ＳＥＭ（倍率３０００倍）観察を行い、Ｃｕ－Ｇａ合金膜上に連続膜領域が形成されるか否かを、以下の基準で評価した。すなわち、純Ｉｎ膜またはＣｕ－Ｉｎ合金膜の厚さは、当該膜を平坦化膜相当に換算した膜厚で算出（純Ｉｎなどのように連続膜を形成しない場合は、化学分析を用いて島状堆積と同じ体積を有する平坦な膜に換算したときの膜厚を算出）し、当該膜厚に対し、連続膜が得られる領域が８０％以上占める場合を◎、３０％以上８０％未満の場合を○、２０％以上３０％未満の場合を△、１０％以上２０％未満の場合を□、１０％未満を×とした。本実施例では、◎、○、△、および□を合格（連続膜の形成あり）と評価した。 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. In the case of ◯, the case of 20% or more and less than 30% is Δ, the case of 10% or more and less than 20% is □, and the case of less than 10% is ×. In this example, ◎, ○, Δ, and □ were evaluated as acceptable (with continuous film formation).
　これらの結果を表１に併記する。 These results are also shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１より、Ｉｎ－Ｃｕ合金膜を用いたＮｏ．１～８、１０では、所望とする連続膜が得られ、特にＩｎ－Ｃｕ合金膜中のＣｕ量を、好ましい範囲である３０～８０原子％に制御したＮｏ．１～８では、より良好な連続膜が得られた。これに対し、従来の純Ｉｎ膜を用いたＮｏ．９では、所定の連続膜が得られなかった。 From Table 1, No. using In—Cu alloy film In Nos. 1-8 and No. 10, a desired continuous film was obtained, and in particular, No. 1 in which the amount of Cu in the In—Cu alloy film was controlled to a preferred range of 30-80 atomic%. For 1 to 8, a better continuous film was obtained. In contrast, No. 1 using a conventional pure In film. In No. 9, a predetermined continuous film was not obtained.
　また表には示していないが、上記のように連続膜が形成されたＮｏ．１～８では、Ｇａの表面拡散を抑制できることを、ＸＰＳ法によって確認している。ＸＰＳ法の測定では、全自動走査型Ｘ線光電子分光分析装置として、Ｐｈｙｓｉｃａｌ Ｅｌｅｃｔｒｏｎｉｃｓ（ＰＨＩ）社製の「Ｑｕａｎｔｅｒａ ＳＸＭ」を用い、線源として、単色化Ａｌ Ｋαを用いた。 Also, although not shown in the table, No. in which the continuous film was formed as described above. In 1 to 8, it was confirmed by XPS that the surface diffusion of Ga can be suppressed. In the measurement of the XPS method, “Quantera® SXM” manufactured by Physical® Electronics (PHI) was used as a fully automatic scanning X-ray photoelectron spectroscopic analyzer, and monochromatic Al®Kα was used as a radiation source.
　よって、このような連続したＩｎ－Ｃｕ合金膜を有するプリカーサーを用いて得られる光吸収層を、太陽電池用の光吸収層として用いれば、光電変換効率の高い電池が得られることが大いに期待される。 Therefore, if a light absorption layer obtained by using a precursor having such a continuous In—Cu alloy film is used as a light absorption layer for a solar cell, it is highly expected that a battery with high photoelectric conversion efficiency can be obtained. The
　実施例２
　本実施例では、第一および第二の工程を行なうことにより；あるいは第二工程によって形成されるＩｎ－Ｃｕ合金膜中のＣｕ量によっては第三工程を行なうことにより、プリカーサーの組成を、高い光電変換効率が実現可能な光吸収層の組成に対応した範囲に調整できることを確認する。ここでは、プリカーサーの好ましい平均組成を、｛Ｃｕ／（Ｉｎ＋Ｇａ）｝の比＝０．８５～０．９９、｛Ｇａ／（Ｉｎ＋Ｇａ）｝の比＝０．１～０．３と設定した。 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 | achieve photoelectric conversion efficiency. Here, the preferable average composition of the precursor was set such that the ratio of {Cu / (In + Ga)} = 0.85 to 0.99 and the ratio of {Ga / (In + Ga)} = 0.1 to 0.3.
　詳細には、表２のＮｏ．６～８は、第一および第二工程を行なうことによって（第三工程なし）、所望とするプリカーサーの組成を実現した例であり、表２のＮｏ．１～５および９は、第一～第三工程を行なうことによって所望とするプリカーサーの組成を実現した例である。Ｎｏ．１～５および９のように第二工程で形成されるＩｎ－Ｃｕ合金膜中のＣｕ量がおおむね４０原子％以上と高く、且つ、当該合金膜の厚さが概ね、１００～５００ｎｍ程度と比較的小さい場合には、純Ｉｎ膜を成膜する第三工程を行なうことが有効であり、これにより、所望組成のプリカーサーが得られる。 For details, see No. 2 in Table 2. Nos. 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. No. As in 1 to 5 and 9, 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. When 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.
　なお、表２のＮｏ．１０は、本発明で用いられるＩｎ－Ｃｕ合金膜を用いない例であり、生産性などを考慮すると実用的でないとの判断から比較例としたものである。詳細には、Ｎｏ．１０では、第二工程で純Ｃｕ膜を成膜（厚さ１００ｎｍ）し、第三工程で純Ｉｎ膜を成膜（厚さ３００ｎｍ）することによって所望組成のプリカーサーを確保したが、所望のプリカーサーを得るために、第三工程で３００ｎｍと厚い純Ｉｎを形成する必要があり、成膜時間増加による純Ｉｎのターゲットの変形などの恐れが高いため、生産性の観点から好ましくないものである。 In Table 2, 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. Specifically, no. 10, 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.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　本出願を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明らかである。
　本出願は、2010年10月5日出願の日本特許出願（特願2010－225591）に基づくものであり、その内容はここに参照として取り込まれる。 Although this application has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on October 5, 2010 (Japanese Patent Application No. 2010-255991), the contents of which are incorporated herein by reference.
　本発明によれば、スパッタリング法によって太陽電池用光吸収層を製造するに当たり、従来のように純Ｉｎ膜を成膜するのではなくＩｎ－Ｃｕ合金膜を用いて製造しているため、島状Ｉｎ膜ではなく連続したＩｎ－Ｃｕ合金膜が得られる。その結果、同一面内での組成が均一で膜質の良好な（すなわち、面内均一性に優れた）光吸収層を、高い生産性で再現性良く成膜できるため、光電変換効率が高い光吸収層の提供が大いに期待される。例えばＣＩＧＳ系光吸収層の製造に当たり、Ｃｕ－Ｇａ合金膜を成膜した後にＩｎ－Ｃｕ合金膜の連続層を成膜すると、ＣｕＧａ膜の露出が防止されるため、大気輸送中などにおけるＧａの酸化を抑制できるほか、その後のセレン化工程が、面と面との反応（ｌａｙｅｒ－ｂｙ－ｌａｙｅｒ）で行なわれるようになるため、面内均一性が一層向上するようになる。 According to the present invention, when manufacturing a light absorption layer for solar cells by sputtering, 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. As a result, a light-absorbing layer having a uniform composition within the same plane and good film quality (ie, excellent in-plane uniformity) can be formed with high productivity and reproducibility. The provision of an absorption layer is highly expected. For example, when manufacturing a CIGS-based light absorption layer, if a continuous layer of In—Cu alloy film is formed after forming a Cu—Ga alloy film, the exposure of the CuGa film is prevented, so that the Ga In addition to being able to suppress oxidation, the subsequent selenization step is performed by a surface-to-surface reaction (layer-by-layer), so that the in-plane uniformity is further improved.

Claims (6)

  1.   Ｃｕと；Ｉｎと；ＧａおよびＡｌのうち少なくとも一種の元素と；Ｓｅを含む化合物半導体薄膜太陽電池用光吸収層の製造方法であって、
      スパッタリングによってＩｎ－Ｃｕ合金膜を成膜する工程を含むことを特徴とする化合物半導体薄膜太陽電池用光吸収層の製造方法。     A method for producing a light-absorbing layer for a compound semiconductor thin-film solar cell, comprising: Cu; In; 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.
  2.   スパッタリングによってＣｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜を成膜する第一の工程と、
      スパッタリングによってＩｎ－Ｃｕ合金膜を成膜する第二の工程と、
      を順次含むものである請求項１に記載の製造方法。     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;
    The manufacturing method of Claim 1 which contains these one by one.
  3. 　第二の工程の後に、スパッタリングによって純Ｉｎ膜を成膜する第三の工程を含む請求項２に記載の製造方法。 The manufacturing method according to claim 2, further comprising a third step of forming a pure In film by sputtering after the second step.
  4.   前記Ｉｎ－Ｃｕ合金膜におけるＣｕの含有量は３０～８０原子％である請求項１～３のいずれか一項に記載の製造方法。 The production method according to claim 1, wherein the content of Cu in the In-Cu alloy film is 30 to 80 atomic%.
  5.   前記Ｃｕ－Ｇａ合金膜またはＣｕ－Ａｌ合金膜と、前記Ｉｎ－Ｃｕ合金膜を連続して形成するものである請求項１～３のいずれか一項に記載の製造方法。 4. The manufacturing method according to claim 1, wherein the Cu—Ga alloy film or Cu—Al alloy film and the In—Cu alloy film are continuously formed.
  6.   Ｃｕと；Ｉｎと；ＧａおよびＡｌのうち少なくとも一種の元素と；Ｓｅを含む化合物半導体薄膜太陽電池用光吸収層の製造に用いられるＩｎ－Ｃｕ合金スパッタリングターゲットであって、
      Ｃｕを３０～８０原子％含有し、残部：Ｉｎおよび不可避不純物であることを特徴とするＩｎ－Ｃｕ合金スパッタリングターゲット。     An In—Cu alloy sputtering target used for manufacturing 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.
PCT/JP2011/072899 2010-10-05 2011-10-04 METHOD FOR MANUFACTURING LIGHT ABSORBING LAYER FOR COMPOUND SEMICONDUCTOR THIN-FILM SOLAR CELL AND In-Cu ALLOY SPUTTERING TARGET WO2012046746A1 (en)

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