JP2012079997A - PRODUCTION METHOD OF LIGHT ABSORPTION LAYER FOR COMPOUND SEMICONDUCTOR THIN FILM SOLAR CELL, AND In-Cu ALLOY SPUTTERING TARGET - Google Patents

PRODUCTION METHOD OF LIGHT ABSORPTION LAYER FOR COMPOUND SEMICONDUCTOR THIN FILM SOLAR CELL, AND In-Cu ALLOY SPUTTERING TARGET Download PDF

Info

Publication number
JP2012079997A
JP2012079997A JP2010225591A JP2010225591A JP2012079997A JP 2012079997 A JP2012079997 A JP 2012079997A JP 2010225591 A JP2010225591 A JP 2010225591A JP 2010225591 A JP2010225591 A JP 2010225591A JP 2012079997 A JP2012079997 A JP 2012079997A
Authority
JP
Japan
Prior art keywords
cu
film
alloy film
ga
sputtering
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
JP2010225591A
Other languages
Japanese (ja)
Inventor
Hideo Fujii
Katsufumi Fuku
勝文 富久
秀夫 藤井
Original Assignee
Kobe Steel Ltd
株式会社神戸製鋼所
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kobe Steel Ltd, 株式会社神戸製鋼所 filed Critical Kobe Steel Ltd
Priority to JP2010225591A priority Critical patent/JP2012079997A/en
Publication of JP2012079997A publication Critical patent/JP2012079997A/en
Application status is Withdrawn legal-status Critical

Links

Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L31/00Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/036Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to 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
    • H01L31/0392Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to 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
    • H01L31/03923Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to 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
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14Metallic material, boron or silicon
    • C23C14/16Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34Sputtering
    • C23C14/3407Cathode assembly for sputtering apparatus, e.g. Target
    • C23C14/3414Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L31/00Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0256Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
    • H01L31/0264Inorganic materials
    • H01L31/032Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
    • H01L31/0322Inorganic 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
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L31/00Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to 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
    • H01L31/072Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to 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
    • H01L31/0749Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and 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 peculiar to 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
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/54Material technologies
    • Y02E10/541CuInSe2 material PV cells
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product
    • Y02P70/52Manufacturing of products or systems for producing renewable energy
    • Y02P70/521Photovoltaic generators

Abstract

Discontinuous layer formation (formation of an island-like In film) when a pure In film is formed by sputtering can be prevented. Preferably, when manufacturing a CIGS light absorption layer containing Ga or the like, Ga is used. The manufacturing method of the light absorption layer for compound thin film solar cells which can suppress the oxidation of is provided.
A method for producing a light-absorbing layer for a compound semiconductor thin film solar cell containing Cu and; at least one element selected from the group consisting of In, Ga, and Al; and Se, wherein the In—Cu layer is formed by sputtering. It is characterized in that it includes a step of forming an alloy film.
[Selection figure] None

Description

  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, and 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.

  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). The 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 composed of a laminate of a Cu—Ga alloy film and a pure In film can be obtained.

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 (a) to (c) are disclosed in order from the substrate side.
(A) 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:
(A) 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:
(C) 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:

  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. Although a film (island-like In film) is formed on the surface, 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.

Japanese Patent No. 4056702 JP 2003-258282 A

  However, the method including the process of forming a pure In film as described in Patent Document 1 has the following problems.

  That is, as described in Patent Document 2 described above, when a pure In film is formed by a sputtering method, In crystals are 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.

  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.

  Also, considering mass productivity, when a pure In film is formed using a pure In target, the distance between the target and the substrate also changes and the effective target surface temperature and the substrate temperature change as the deposition proceeds. 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.

  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.

  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.

  The method for producing a light-absorbing layer for a compound semiconductor thin film solar cell according to the present invention that has solved the above-described problems includes Cu; and at least one element selected from the group consisting of In, Ga, and Al; and Se It is a manufacturing method of the light absorption layer for compound semiconductor thin film solar cells, Comprising: It has a summary in the place including the process of forming an In-Cu alloy film by sputtering.

  In a preferred embodiment of the present invention, the manufacturing method includes a first step of forming a Cu—Ga alloy film or a Cu—Al alloy film by sputtering, and a second step of forming an In—Cu alloy film by sputtering. The process and the 3rd process of forming a pure In film | membrane by sputtering as needed are included in order.

  In a preferred embodiment of the present invention, the Cu—Ga alloy film or Cu—Al alloy film and the In—Cu alloy film are formed continuously.

  In preferable embodiment of this invention, content of Cu in the said In-Cu alloy film is 30-80 atomic%.

  Moreover, the sputtering target of the present invention capable of solving the above-mentioned problems is a sputtering target used for producing the light-absorbing layer for a compound semiconductor thin film solar cell, containing 30 to 80 atomic% of Cu, and the balance: In and It has a gist where it is an inevitable impurity.

  According to the present invention, when manufacturing a light absorption layer for a solar cell by a sputtering method, 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 an In—Cu alloy film is formed after forming a Cu—Ga alloy film, the exposure of the CuGa film is prevented. 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.

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) 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.

  The reason why a continuous In—Cu alloy film can be obtained as shown in FIGS. 3 to 5 to be described later by the formation of the In—Cu alloy film by the sputtering method is not clear in detail. It is presumed that the intermetallic compound of In—Cu works effectively as a nucleation site.

  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 when 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.

  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%, and FIG. 4 shows the Cu amount≈55 atomic%. 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, and 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-shaped In region is formed on an In—Cu alloy film (continuous film), and as described later, in the present invention, the preferable amount of Cu in the In—Cu alloy film is appropriately controlled. It is presumed that there is no fear of the performance deterioration of the solar cell due to the formation of the island-like 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.

  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, if the amount of Cu is within the above range, the desired continuous film of In—Cu alloy (preferably It can be seen that a continuous film whose surface is further planarized is obtained.

As described above, the method for producing a solar cell light absorption layer according to the present invention is characterized in that it includes a step of forming a Cu-Ga 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 the manufacturing process, at least a step of forming a Cu—Ga alloy film by a sputtering method may be included. Typically, an embodiment including the following steps may be mentioned:
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.

  Hereinafter, although the 1st-3rd each process in the said embodiment is demonstrated in detail, this invention is not the meaning limited to this.

(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, and 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, etc. It is preferable to be within the range of 50 atomic% and Al: 2 to 40 atomic%.

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 1.0-8W / cm 2 (standardized by the area of 4 inch φ target)
Substrate temperature: room temperature to 300 ° C

(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 step is a step characterizing the present invention, and a technique using an In—Cu alloy film has not been known so far in 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 on a pure In target. The In—Cu alloy target used in the present invention is novel, and details will be described later.

  The content of Cu in the In—Cu alloy film is preferably 30 to 80 atomic%, whereby a desired continuous film is obtained. When 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 a clear continuous film region cannot be obtained. From the viewpoint of making the region covering the lower layer 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%.

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 0.5-5W / cm 2 (standardized by the area of 4 inch φ target)
Substrate temperature: room temperature to 300 ° C

  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. .

  In the present invention, the composition of the precursor before selenization can be adjusted to obtain the 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.

  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 terms of adjusting the composition of the precursor, a combination of a plurality of stacking orders is conceivable. However, in the present invention, a Cu-Ga alloy film or Cu-Al 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 are 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 directly below.

  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 structure of the precursor is a laminate of a Cu—Ga alloy film, an In—Cu alloy film, and a pure In film in order from the substrate side.

(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. However, since this island-like In film is formed on the continuous film, light absorption is performed. 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 a range of about 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

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 step is roughly classified into a gas phase method using H 2 and / or H 2 S, a solid phase method not using H 2 , 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.

  In addition, said embodiment is a preferable example of this invention, This invention is not the meaning limited to this, The manufacturing process (strictly) of the solar cell light absorption layer including the film-forming process of In-Cu alloy film by sputtering All of the precursor film formation step before selenization is included in the scope of the present invention.

  For example, in the above embodiment, a Cu—Al alloy film may be used instead of the Cu—Ga alloy film. In this case, 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.

  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 film having a Cu content of about 60 to 80 atoms. That is, instead of securing a predetermined thickness with one In—Cu film as in the above-described embodiment, a method of distributing the film thickness by interposing two In—Cu films as in Modification 1 above. If 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, the band gap is widened, and as a result, the photoelectric conversion efficiency is increased. A high light absorption layer can be obtained.

  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.

  The solar cell light absorption layer 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.

  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.

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.

In detail, Cu of the composition and thickness shown in Table 1 using various Cu-Ga alloy targets with different amounts of Ga on a low Na glass substrate (Techno Quartz 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

Next, sputtering using a pure In target or sputtering with a Cu chip chip-on on the pure In target is performed on the Cu—Ga alloy film, and the 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

  The cross section in the film thickness direction of each precursor thus obtained is observed by SEM (magnification 3000 times), and whether or not a continuous film region is formed on the Cu—Ga alloy film is evaluated according to the following criteria. did. That is, the thickness of the pure In film or the Cu—In alloy film is calculated by the film thickness equivalent to the flattened film (when a continuous film is not formed like pure In or the like, 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).

  These results are also shown in Table 1.

  From Table 1, No. 1 using an In—Cu alloy film was obtained. In Nos. 1-8, 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 preferable range of 30-80 atomic%. In 1 to 8, better continuous films were obtained. In contrast, No. 1 using a conventional pure In film. In No. 9, a predetermined continuous film was not obtained.

  Further, although not shown in the table, No. 1 in which the continuous film was formed as described above. 1 to 8 confirms that the surface diffusion of Ga can be suppressed by the XPS method. In the XPS measurement, “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.

  Therefore, if a light absorption layer obtained 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

Example 2
In this example, the precursor composition is increased 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. 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.

  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). 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 1-5 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 generally compared with about 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.

  In Table 2, No. 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 considering productivity and the like. 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.

Claims (5)

  1. A method for producing a light-absorbing layer for a solar cell, comprising: Cu; at least one element selected from the group consisting of In, Ga, and Al;
    The manufacturing method of the light absorption layer for compound semiconductor thin film solar cells characterized by including the process of forming an In-Cu alloy film by sputtering.
  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;
    A third step of forming a pure In film by sputtering, if necessary;
    The manufacturing method of Claim 1 which contains these one by one.
  3.   The manufacturing method according to claim 1 or 2, wherein the Cu-Ga alloy film or Cu-Al alloy film and the In-Cu alloy film are continuously formed.
  4.   The manufacturing method according to claim 1, wherein the content of Cu in the In—Cu alloy film is 30 to 80 atomic%.
  5. A sputtering target used for manufacturing a light-absorbing layer for a compound semiconductor thin film solar cell containing Se; and at least one element selected from the group consisting of In, Ga, and Al;
    A sputtering target comprising 30 to 80 atomic% of Cu, the balance being In and inevitable impurities.
JP2010225591A 2010-10-05 2010-10-05 PRODUCTION METHOD OF LIGHT ABSORPTION LAYER FOR COMPOUND SEMICONDUCTOR THIN FILM SOLAR CELL, AND In-Cu ALLOY SPUTTERING TARGET Withdrawn JP2012079997A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2010225591A JP2012079997A (en) 2010-10-05 2010-10-05 PRODUCTION METHOD OF LIGHT ABSORPTION LAYER FOR COMPOUND SEMICONDUCTOR THIN FILM SOLAR CELL, AND In-Cu ALLOY SPUTTERING TARGET

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2010225591A JP2012079997A (en) 2010-10-05 2010-10-05 PRODUCTION METHOD OF LIGHT ABSORPTION LAYER FOR COMPOUND SEMICONDUCTOR THIN FILM SOLAR CELL, AND In-Cu ALLOY SPUTTERING TARGET
PCT/JP2011/072899 WO2012046746A1 (en) 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
TW100136086A TWI460874B (en) 2010-10-05 2011-10-05 Method for manufacturing a light absorbing layer for a compound semiconductor thin film solar cell, and an In-Cu alloy sputtering target

Publications (1)

Publication Number Publication Date
JP2012079997A true JP2012079997A (en) 2012-04-19

Family

ID=45927741

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2010225591A Withdrawn JP2012079997A (en) 2010-10-05 2010-10-05 PRODUCTION METHOD OF LIGHT ABSORPTION LAYER FOR COMPOUND SEMICONDUCTOR THIN FILM SOLAR CELL, AND In-Cu ALLOY SPUTTERING TARGET

Country Status (3)

Country Link
JP (1) JP2012079997A (en)
TW (1) TWI460874B (en)
WO (1) WO2012046746A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017106091A (en) * 2015-12-11 2017-06-15 Jx金属株式会社 In-Cu ALLOY SPUTTERING TARGET AND PRODUCTION METHOD THEREOF

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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 (en) 2013-01-31 2014-03-15 Plansee Se CU-GA-IN-NA Target

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0483378A (en) * 1990-07-25 1992-03-17 Matsushita Electric Ind Co Ltd Manufacture of chalcopyrite thin film and solar cell
JP2848993B2 (en) * 1991-11-21 1999-01-20 株式会社富士電機総合研究所 Method and apparatus for manufacturing a thin film solar cell
US5730852A (en) * 1995-09-25 1998-03-24 Davis, Joseph & Negley Preparation of cuxinygazsen (X=0-2, Y=0-2, Z=0-2, N=0-3) precursor films by electrodeposition for fabricating high efficiency solar cells
JP3811825B2 (en) * 2001-07-06 2006-08-23 本田技研工業株式会社 The method of forming the light absorbing layer
JP2003282600A (en) * 2002-03-25 2003-10-03 Honda Motor Co Ltd Method and device for manufacturing light-absorbing layer
ES2366888T5 (en) * 2003-08-14 2018-05-17 University Of Johannesburg Method of preparing semiconductor films of quaternary alloys or higher of the IB-IIIA-VIA groups
US7374963B2 (en) * 2004-03-15 2008-05-20 Solopower, Inc. Technique and apparatus for depositing thin layers of semiconductors for solar cell fabrication
US20070111367A1 (en) * 2005-10-19 2007-05-17 Basol Bulent M Method and apparatus for converting precursor layers into photovoltaic absorbers
TWM385798U (en) * 2010-02-25 2010-08-01 Univ Minghsin Sci & Tech Photovoltaic cell structure

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017106091A (en) * 2015-12-11 2017-06-15 Jx金属株式会社 In-Cu ALLOY SPUTTERING TARGET AND PRODUCTION METHOD THEREOF

Also Published As

Publication number Publication date
TWI460874B (en) 2014-11-11
TW201220522A (en) 2012-05-16
WO2012046746A1 (en) 2012-04-12

Similar Documents

Publication Publication Date Title
Kessler et al. Technological aspects of flexible CIGS solar cells and modules
Kaelin et al. Low-cost CIGS solar cells by paste coating and selenization
EP1654769B1 (en) Method for the preparation of group ib-iiia-via quaternary or higher alloy semiconductor films
Niki et al. CIGS absorbers and processes
Tanaka et al. Chemical composition dependence of morphological and optical properties of Cu2ZnSnS4 thin films deposited by sol–gel sulfurization and Cu2ZnSnS4 thin film solar cell efficiency
Moholkar et al. Development of CZTS thin films solar cells by pulsed laser deposition: influence of pulse repetition rate
RU2404484C2 (en) Electrode structure for use in electronic device and method of making said electrode structure
CN102347398B (en) Sodium sputtering doping method cigs mass based thin-film photovoltaic material
CN100530701C (en) Manufacturing apparatus and method for large-scale production of thin-film solar cells
US8188367B2 (en) Multilayer structure to form absorber layers for solar cells
Fairbrother et al. Secondary phase formation in Zn‐rich Cu2ZnSnSe4‐based solar cells annealed in low pressure and temperature conditions
KR101623051B1 (en) Manufacturing method of cis thin-film solar cell
US7989256B2 (en) Method for manufacturing CIS-based thin film solar cell
KR20090106513A (en) Doping techniques for group ?????? compound layers
JPH09506475A (en) Semiconductor device forming thin film Cu (In, Ga) Se ▲ under 2 ▼ method selenide recrystallization
US20100282300A1 (en) Method for producing an electrode made with molybdenum oxide
JP2007502536A (en) The novel metal strip
JP2006186200A (en) Precursor film and film formation method therefor
US8969720B2 (en) Photoelectronically active, chalcogen-based thin film structures incorporating tie layers
TWI427814B (en) Method of manufacturing solar cell
JP2011517132A (en) Glass substrate to support the electrode
CN101740660B (en) Copper indium gallium selenium (CIGS) solar cell, film of absorbing layer thereof, method and equipment for preparing film
US20080023336A1 (en) Technique for doping compound layers used in solar cell fabrication
KR20100029414A (en) Solar cell and method of fabricating the same
Yun et al. Fabrication of CIGS solar cells with a Na-doped Molayer on a Na-free substrate

Legal Events

Date Code Title Description
A300 Withdrawal of application because of no request for examination

Free format text: JAPANESE INTERMEDIATE CODE: A300

Effective date: 20140107