WO2013035876A1 - Appareil de dépôt en bain chimique, procédé de formation de couche tampon et procédé de fabrication de dispositif de conversion photoélectrique - Google Patents

Appareil de dépôt en bain chimique, procédé de formation de couche tampon et procédé de fabrication de dispositif de conversion photoélectrique Download PDF

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WO2013035876A1
WO2013035876A1 PCT/JP2012/073002 JP2012073002W WO2013035876A1 WO 2013035876 A1 WO2013035876 A1 WO 2013035876A1 JP 2012073002 W JP2012073002 W JP 2012073002W WO 2013035876 A1 WO2013035876 A1 WO 2013035876A1
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Prior art keywords
substrate
reaction solution
temperature
buffer layer
photoelectric conversion
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PCT/JP2012/073002
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English (en)
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Tetsuo Kawano
Hiroshi Arai
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Fujifilm Corporation
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Priority claimed from JP2011192896A external-priority patent/JP2013052361A/ja
Priority claimed from JP2012169379A external-priority patent/JP2013070032A/ja
Application filed by Fujifilm Corporation filed Critical Fujifilm Corporation
Priority to KR1020147009031A priority Critical patent/KR20140062510A/ko
Priority to CN201280052384.0A priority patent/CN103906857A/zh
Publication of WO2013035876A1 publication Critical patent/WO2013035876A1/fr
Priority to US14/196,338 priority patent/US20140186988A1/en

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    • H—ELECTRICITY
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    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02436—Intermediate layers between substrates and deposited layers
    • H01L21/02439—Materials
    • H01L21/02485—Other chalcogenide semiconducting materials not being oxides, e.g. ternary compounds
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    • 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
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
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    • C23C18/1601—Process or apparatus
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    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
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    • 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
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
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    • C23C18/163—Supporting devices for articles to be coated
    • 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
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
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    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1675—Process conditions
    • C23C18/1678—Heating of the substrate
    • 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
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1675—Process conditions
    • C23C18/168—Control of temperature, e.g. temperature of bath, substrate
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    • H01L21/02367—Substrates
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    • H01L21/02422—Non-crystalline insulating materials, e.g. glass, polymers
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    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
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    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
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    • H01L21/02494—Structure
    • H01L21/02496—Layer structure
    • H01L21/02502—Layer structure consisting of two layers
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    • H01L21/02521—Materials
    • H01L21/02551—Group 12/16 materials
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    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/036—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
    • H01L31/0392—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
    • H01L31/03923—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate including AIBIIICVI compound materials, e.g. CIS, CIGS
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/541—CuInSe2 material PV cells
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Definitions

  • the present invention relates to a chemical bath deposition apparatus for use in forming a buffer layer of a photoelectric conversion device, or the like.
  • the present invention also relates to a method of forming a buffer layer of a photoelectric conversion device using a chemical bath deposition process, and a method of manufacturing a photoelectric conversion device.
  • Photoelectric conversion devices which include a photoelectric conversion layer and electrodes electrically connected with the photoelectric conversion layer, are used in applications, such as solar batteries.
  • the main stream of conventional solar batteries has been Si solar batteries, which use bulk single-crystal Si or polycrystal Si, or thin-film amorphous Si.
  • compound semiconductor solar batteries which do not depend on Si, are now being researched and developed.
  • As the compound semiconductor solar batteries those of a bulk type, such as GaAs solar batteries, etc., and those of a thin-film type, such as CIS or CIGS solar batteries, which contain a group lb element, a group Illb element and a group VIb element, are known.
  • CI(G)S is a compound semiconductor represented by the general formula below:
  • Conventional thin-film type photoelectric conversion devices such as CI (G) S photoelectric conversion devices, typically include a buffer layer (a Cd compound, such as CdS or a Zn compound, such as Zn(0,OH, S) ) between the photoelectric conversion layer and a transparent conductive layer (transparent electrode) which is formed above the photoelectric conversion layer.
  • the buffer layer in such a system is usually formed by a chemical bath deposition (CBD) process .
  • Functions of the buffer layer may include (1) prevention of recombination of photogenerated carriers, (2) control of band discontinuity, (3) lattice matching, (4) coverage of surface unevenness of the photoelectric conversion layer, etc.
  • a CBD (Chemical Bath Deposition) process which is a liquid phase process, may preferably be used to satisfy the condition (4) above.
  • the buffer layer is formed on the photoelectric conversion layer typically by immersing a substrate, which has the photoelectric conversion layer formed on the surface thereof, in a reaction solution heated to a predetermined temperature .
  • the CBD process has problems, such that particles (colloid) are formed in the reaction solution at the same time when the buffer layer is deposited on the photoelectric conversion layer, and the particles adhere to the surface on which the buffer layer is formed, and that it is difficult to achieve cost reduction and mass productivity is low because the reaction solution cannot be used repeatedly. It should be noted that, if a buffer layer with such particles adhering to the surface on which the buffer layer is formed is used to form a photoelectric conversion device, the resulting photoelectric conversion device may have degraded performance .
  • Patent Document 1 Japanese Unexamined Patent Publication No. 7 (1995) -240385 has disclosed a method and an apparatus for forming CdS, which allows mass production of CdS. Specifically, Patent Document 1 has proposed a method for forming a CdS film, wherein the temperature of a substrate holder is set to a temperature at which CdS forms on a substrate (for example, 60 °C) , and the temperature of a solution is maintained at a temperature at which no CdS forming reaction occurs (40 °C or less) . Patent Document 1 teaches that this allows continuous film formation without CdS forming at areas other than the substrate.
  • Patent Document 2 Japanese Unexamined Patent Publication No. 2009-259938
  • Patent Document 2 has disclosed a film forming method, which achieves cost reduction by reducing the used amount of a material solution.
  • Patent Document 2 has proposed an apparatus, wherein a necessary amount of solution is dripped on a surface of a substrate and a holding section holding the substrate is heated.
  • Patent Document 2 teaches that this allows reduction of the used amount of the solution and highly accurate control of the substrate temperature distribution, therebyproviding a process that can provide a film having good film thickness distribution and film quality distribution while reducing a film formation time.
  • Patent Document 3 U.S. Patent Application Publication No. 20110027938
  • the formation of particles in the reaction solution can be suppressed, thereby reducing adhesion of the particles to the surface on which the buffer layer is formed. This is also believed to allow repeated use of the reaction solution, thereby allowing cost reduction and mass production.
  • the buffer layer forming process using the CBD process determines the production rate. Therefore, there is a need for reducing production time of the buffer layer forming process.
  • the present invention is directed to providing a practical chemical bath deposition apparatus, which can achieve cost reduction by suppressing formation of particles in a reaction solution, and can achieve a higher quality buffer layer.
  • the present invention is also directed to providing a method of forming a buffer layer using a CBD process, which can achieve cost reduction by suppressing formation of particles in a reaction solution, and can achieve time reduction of a buffer layer forming process .
  • An aspect of the chemical bath deposition apparatus of the invention includes: a reaction vessel for containing a reaction solution for chemical bath deposition to form a film on a surface of a substrate; a substrate holding section for holding the substrate such that at least the surface of the substrate contacts the reaction solution, the substrate holding section including a fixing surface made of stainless steel or titanium on which a back side of the substrate is closely fixed; a heater disposed at a rear side of the fixing surface, the heater heating the substrate from the back side of the substrate; and a reaction solution temperature control unit for controlling temperature of the reaction solution in the reaction vessel.
  • the heater may preferably be a sheet heater disposed across an area larger than an area of the fixing surface where the substrate is fixed.
  • the heater may particularly preferably be a rubber heater.
  • the substrate holding section may preferably hold the substrate such the surface of the substrate is oriented in a vertically downward direction (i.e., the surface of the substrate faces the bottom surface of the reaction vessel) .
  • the fixing surface of the substrate holding section is a semi-cylindrical surface.
  • the substrate holding section may preferably hold the substrate such that the surface of the substrate is inclined from the vertically downward direction.
  • the substrate holding section may hold the substrate parallel to a side wall surface of the reaction vessel.
  • the substrate holding section may preferably include an end face protective member for preventing a side end face of the substrate fixed on the fixing surface from contacting the reaction solution.
  • At least an area of an inner wall of the reaction vessel contacting the reaction solution is coated with a hydrophobic material.
  • An aspect of the method of forming a buffer layer of the invention is a method of forming a buffer layer of a photoelectric conversion device having a layered structure formed on a substrate, the layered structure including a lower electrode, a photoelectric conversion semiconductor layer, the buffer layer and a transparent conductive layer, the method using an apparatus including: a reaction vessel containing a reaction solution for chemical bath deposition to form the buffer layer; a substrate holding section for holding the substrate having the photoelectric conversion semiconductor layer formed thereon such that at least a surface of the photoelectric conversion semiconductor layer contacts the reaction solution; a heater for heating the substrate; and a reaction solution temperature control unit for controlling temperature of the reaction solution, the method including: mounting the substrate having the photoelectric conversion semiconductor layer forming an outermost surface thereof on the substrate holding section; heating the substrate by the heater to a temperature ⁇ [°C] ; starting formation of the buffer layer by bringing at least the surface of the photoelectric conversion semiconductor layer into contact with the reaction solution, the temperature of the reaction solution being controlled to a temperature T 2 [°C]
  • the description "maintaining the substrate at the temperature i and the reaction solution at the temperature T 2 " means that temperatures set at the heater and the reaction solution temperature control unit are maintained at the temperatures Ti, T 2 , respectively.
  • the actual temperatures of the substrate and the reaction solution may change immediately after the substrate is brought into contact with the reaction solution.
  • the heater and the reaction solution temperature control unit function to bring these temperatures to Ti, T 2 (close to Ti, T 2 ) , respectively.
  • the buffer layer is a Zn compound layer
  • the temperatures Ti [°C] and T 2 [°C] satisfy the relationship below:
  • the Zn compound is one of ZnS, Zn(S,0) and Zn(S,0,OH).
  • An aspect of the method of manufacturing a photoelectric conversion device of the invention is a method of manufacturing a photoelectric conversion device having a layered structure formed on a substrate, the layered structure including a lower electrode, a photoelectric conversion semiconductor layer, a buffer layer and a transparent conductive layer, the method comprising: forming the buffer layer by the method of forming a buffer layer of the invention.
  • the chemical bath deposition apparatus of the invention includes the heater for heating the substrate from the back side thereof and the reaction solution temperature control unit for controlling the reaction solution temperature which are independent from each other, so that the substrate temperature and the reaction solution temperature can be controlled independently.
  • This allows controlling the substrate temperature and the reaction solution temperature to be the same temperature to provide a more uniform temperature of the reaction solution in the reaction vessel, or setting the substrate temperature higher than the reaction solution temperature to suppress the formation of particles (colloid) in the reaction solution to allow selective film formation on the substrate . Suppressing the formation of particles (colloid) allows repeated use of the reaction solution, thereby achieving cost reduction.
  • the fixing surface, on which the substrate is fixed is made of stainless steel or titanium, and can therefore transmit the heat from the heater for heating the substrate to the substrate uniformly and at high thermal conductivity, thereby achieving highly uniform heating of the substrate. This improves the thickness uniformity of the formed layer, resulting in a buffer layer having higher quality than that of prior art buffer layers.
  • the substrate is heated to the temperature Ti [°C] by the heater, and then at least the surface of the photoelectric conversion semiconductor layer is brought into contact with the reaction solution, which is controlled to the temperature T 2 [°C] lower than the temperature Ti . Therefore, the deposition starts soon after the substrate is immersed in the reaction solution, and a time taken for formation of the buffer layer is reduced compared to a case where the substrate temperature is raised after the substrate has been brought into contact with the reaction solution.
  • FIG. 1 is a sectional view illustrating the schematic structure of a chemical bath deposition apparatus according to an embodiment of the present invention
  • FIG. 2 is a perspective view of the chemical bath deposition apparatus shown in FIG. 1,
  • FIG. 3 is a cross-sectional schematic diagram illustrating a modification of a substrate holding section
  • FIG. 4 is a cross-sectional schematic diagram illustrating a photoelectric conversion device of one embodiment, which is manufactured by a method of manufacturing a photoelectric conversion device of the invention
  • FIG. 5 is a schematic diagram illustrating the schematic structure of a CBD apparatus used in Example 1-4 and Example 2-2
  • FIG. 6 is a schematic diagram illustrating the schematic structure of a CBD apparatus used in Comparative Example 1-1 and Comparative Example 2-3
  • FIG. 5 is a schematic diagram illustrating the schematic structure of a CBD apparatus used in Example 1-4 and Example 2-2
  • FIG. 6 is a schematic diagram illustrating the schematic structure of a CBD apparatus used in Comparative Example 1-1 and Comparative Example 2-3
  • FIG. 7 is a schematic diagram illustrating the schematic structure of a CBD apparatus used to carry out a CBD process of Comparative Example 2-2.
  • FIG. 1 is a cross-sectional schematic diagram illustrating a chemical bath deposition apparatus 1 according to an embodiment of the invention (which will hereinafter be referred to as "CBD apparatus 1")
  • FIG. 2 is a perspective view illustrating the schematic structure of the CBD apparatus 1 shown in FIG. 1.
  • the CBD apparatus 1 includes: a reaction vessel 3 containing a reaction solution 2 used to deposit a film (buffer layer) by chemical bath deposition on a surface 10a of a substrate 10; a substrate holding section (substrate holder) 20 for holding the substrate 10; a heater 30 for heating the substrate 10 from the back side thereof; and a reaction solution temperature control unit 40 for controlling the temperature of the reaction solution 2 contained in the reaction vessel 3.
  • a reaction vessel 3 containing a reaction solution 2 used to deposit a film (buffer layer) by chemical bath deposition on a surface 10a of a substrate 10
  • a substrate holding section (substrate holder) 20 for holding the substrate 10
  • a heater 30 for heating the substrate 10 from the back side thereof
  • a reaction solution temperature control unit 40 for controlling the temperature of the reaction solution 2 contained in the reaction vessel 3.
  • the substrate holder 20 includes: a stainless steel plate member 21 forming the bottom surface of the substrate holder 20, which includes a fixing surface 21a, on which the substrate 10 is closely fixed; a holder body 23 in the form of a vessel, which includes a wall surface 22 formed continuously from the bottom surface formed by the plate member 21; and a support 26, which is connected to the holder body 23 and can be hung across a part of the reaction vessel 3.
  • the fixing surface 21a bulges in a semi-cylindrical shape such that the center of the fixing surface 21a in the horizontal direction in FIG.1 is nearest to the bottom surface, and the substrate 10 is fixed along the fixing surface 21a with being bent along the curved surface thereof.
  • the substrate 10 is held such that the surface, on which the buffer layer is formed, is oriented in the vertically downward direction (the axis A in FIG. 1) (i.e., faces the bottom surface of the reaction vessel) . Fixing the substrate 10 with bending the substrate 10 in this manner minimizes adhesion of air bubbles to the surface 10a, which is now a curved surface.
  • the buffer layer is not deposited on the areas of the surface to which the air bubbles adhere, and it is difficult form a perfect film of the buffer layer. That is, in a case where the fixing surface is a flat surface and the substrate is held such that the surface on which the buffer layer is formed is horizontal relative to a reaction solution surface 2a, that is, the flat surface 10a is oriented in the vertically downward direction, the air bubbles may adhere to the surface on which the buffer layer is formed, which may result in a partially defective film of the buffer layer.
  • an underlying substrate 11 of the substrate 10 is flexible enough to be bent along the curvature of the fixing surface.
  • the radius of curvature of the curved surface may preferably be in the range from 100 mm to 10000 mm, although it depends on the size of the reaction vessel, etc.
  • stainless steel plate member As a material forming the stainless steel plate member, SUS316 (JIS standard), which is alkali-resistant, is most preferable.
  • the surface of stainless steel may be coated with a heat-resistant and alkali-resistant material, such as Teflon (R) or a carbon-based material (for example, a carbon material or a carbon compound, such as SiC) .
  • the substrate holder 20 is adapted to hold the substrate 10 on the fixing surface 21a with a liquid-leakage prevention jig 24, which grasps the substrate 10 against the substrate holder body 23, such that only the surface 10a (on which the buffer layer is formed) is able to contact the reaction solution 2.
  • the substrate holder 20 is further adapted to hold the substrate 10 with a clamping frame 25, which clamps the liquid-leakage prevention jig 24 and the substrate 10 so that no reaction solution 2 penetrate through a gap between the liquid-leakage prevention jig 24 and the substrate 10.
  • the liquid-leakage prevention jig 24 and the clamping frame 25 form an end face protective member for preventing a side end face of the substrate from contacting the reaction solution.
  • a base material such as anAl base material, which may possibly be eroded by the reaction solution 2, may also be used as the underlying substrate 11.
  • the heater 30 is a sheet heater that is uniformly disposed on the surface of the stainless steel plate member 21 of the holder body 23 opposite from the fixing surface 21a, i.e., the inner bottom surface of the holder body 23, to span over an area larger than the area of the substrate 10.
  • the heater 30 is a rubber heater.
  • the reaction solution temperature control unit 40 includes: a temperature controlling means 41 disposed on the bottom surface of the reaction vessel 3; and a temperature measuring unit 42 for measuring a reaction solution temperature around the bottom surface.
  • the temperature controlling means 41 includes heating and/or cooling means.
  • the heating means may be any of various heaters.
  • the cooling means may include a water-cooling device such as one using coldwater, an air-cooling device, such as a fan, a heat sink, etc.
  • the reaction solution temperature is defined as a reaction solution temperature in the vicinity of the temperature controlling means 41.
  • the temperature controlling means 41 may separately include a thermostatic chamber, so that the reaction solution temperature is kept constant by circulating the reaction solution. However, it is more preferable that the reaction solution is not circulated during the film formation because circulating the reaction solution promotes formation of particles (colloid) in the reaction solution.
  • the CBD apparatus 1 of the invention includes the heater 30 for heating the substrate 10 and the reaction solution temperature control unit 40 for controlling the reaction solution temperature which are independent from each other, so that the temperature of the substrate 10 and the reaction solution temperature can be controlled independently.
  • This allows controlling the substrate temperature and the reaction solution temperature to be the same temperature to provide a more uniform reaction solution temperature, or varying the substrate temperature and the reaction solution temperature (for example, raising the reaction solution temperature in the vicinity of the substrate to a reaction temperature (around 70-90 °C) and controlling the reaction solution temperature in the vicinity of the reaction solution temperature control unit to be lower than the reaction temperature) to suppress the formation of particles (colloid) in the reaction solution, thereby allowing selective film formation on the substrate.
  • the inner wall of the reaction vessel 3 is preferably coated with an alkali-resistant hydrophobic material.
  • the coating of the hydrophobic material minimizes deposition of the film on the inner wall during the film deposition on the substrate, thereby saving material consumption and time and labor for maintenance.
  • the deposited material adheres to the inner wall after a long time of the film forming process.
  • a deposited material can be dissolved and removed by washing with an aqueous hydrochloric solution, or the like. Therefore, the hydrophobic material used to coat the inner wall is preferably alkali-resistant and acid-resistant.
  • the coatingmaterial is Teflon (R).
  • the fixing surface, on which the substrate 10 is fixed is made of stainless steel, and can therefore transmit the heat from the substrate-heating heater 30 to the substrate uniformly and at high thermal conductivity, thereby achieving highly uniform heating of the substrate. This improves the thickness uniformity of the formed layer.
  • FIG. 3 is a cross-sectional schematic diagram illustrating a modification 20' of the substrate holder.
  • the substrate fixing surface 21a of the substrate holder 20 has a curved surface.
  • a stainless steel plate member 27 may not be curved so that it has a flat fixing surface 27a.
  • the substrate 10 may be held such that the surface 10a is inclined from the vertically downward direction (i.e., the surface 10a is inclined from the direction parallel to the surface 2a of the reaction solution) (as shown by the dashed lines in FIG. 3) .
  • the angle of inclination of the substrate is preferably in the range from 1 to 30 degrees.
  • the substrate fixing surface 21a is a curved surface
  • the underlying substrate 11 of the substrate 10 is flexible.
  • a non-flexible substrate such as a glass substrate, may also be used.
  • the CBD apparatus may preferably include a plurality of material solution tanks for containing various material solutions forming the reaction solution, a tank for mixing the material solutions, and a piping line for pouring the thus prepared mixed reaction solution into the reaction vessel. Further, the CBD apparatus may preferably include a piping line for circulating and filtering the reaction solution in the reaction vessel to collect the particles (colloid) , etc., formed in the reaction solution and return the solution to the reaction vessel . As descried previously, circulating the reaction solution promotes the formation of particles (colloid) , and therefore it is preferable to circulate the reaction solution during interval periods between the film formation processes, not during the film formation process.
  • the CBD apparatus may include a transmittance measuring unit for measuring transmittance of the reaction solution.
  • a transmittance measuring unit for measuring transmittance of the reaction solution.
  • a relationship between decrease of the transmittance and the thickness of the formed film may be determined in advance, and the transmittance of the reaction solution may be measured in-situ, so that the film formation is ended based on the decrease of transmittance.
  • the CBD apparatus may include a pHmeasuring unit for measuring pH of the reaction solution.
  • the CBD apparatus may include an electric conductivity measuring unit for measuring electric conductivity of the reaction solution.
  • an electric conductivity measuring unit for measuring electric conductivity of the reaction solution.
  • a relationship between change of the electric conductivity and the thickness of the formed film may be determined in advance, and the electric conductivity of the reaction solution may be measured in-situ, so that the film formation is ended based on the amount of change of electric conductivity.
  • the change of transmittance, pH or electric conductivity may be used to detect the end of the useful life of the reaction solution.
  • time to add a fresh reaction solution or recycled solution may be determined using the change of transmittance, pH or electric conductivity.
  • Metallic parts of the CBD apparatus 1 which may possibly contact the CBD solution, such as the substrate holder, may preferably be made of an alkali-resistant material, such as SUS316.
  • the inner wall of the reaction vessel 3 may preferably be coated with Teflon (R) .
  • the substrate holder may be adapted to be rotatable so that the substrate holder is rotated during the film formation. This is believed to minimize unevenness of the deposition, thereby achieving higher uniformity of the formed film.
  • the CBD apparatus 1 is placed in a housing (not shown) to prevent dust, etc., from entering in the apparatus.
  • An exhaust port for discharging the alkaline gas may preferably be provided in the housing.
  • the housing may preferably be provided with an antistatic function to prevent adhesion of dust.
  • the antistatic function may be provided by applying an antistatic agent on the housing, or by forming the housing from a resin material in which an electrically conductive material is mixed.
  • the CBD apparatus 1 shown in FIG. 1 is configured such that a square substrate is mounted one by one on the substrate holder 20, with assuming that the film formation is carried out in a batch process.
  • the invention is not limited to a batch process, and is also applicable to film formation carried out in a roll-to-roll process.
  • the substrate holder includes a mechanism that can sequentially mount portions of a roll-shaped substrate. 1
  • the substrate holder may include a drum-shaped rotating holder body made of stainless steel, and the drum surface may be adapted such that portions of a long substrate is sequentially mounted on the fixing surface.
  • the heater may be disposed inside the drum.
  • the CBD apparatus of the invention is preferably applicable to formation of a buffer layer of a photoelectric conversion device, which includes a lower electrode, a photoelectric conversion semiconductor layer, the buffer layer and a transparent electrode formed on a substrate.
  • the above-described CBD apparatus 1 is used to form a buffer layer of a photoelectric conversion device, which has a layered structure formed on a substrate, the layered structure including a lower electrode, a photoelectric conversion semiconductor layer, the buffer layer and a transparent conductive layer.
  • the substrate 10 including the lower electrode (not shown in FIGs. 1 and 2) and the photoelectric conversion semiconductor layer 13 sequentially formed on the substrate 11 is prepared (on which the buffer layer is formed) , and the substrate 10 is mounted on the substrate holder 20. Then, the substrate 10 is heated by the heater to a temperature Ti [°C].
  • the surface of the photoelectric conversion semiconductor layer 13 is brought into contact with the reaction solution, which is controlled to a temperature T 2 [°C] lower than the temperature Ti, while the heated state of the substrate 10 is maintained (while heating the substrate 10 with the heater) .
  • T 2 [°C] a temperature lower than the temperature Ti
  • the back side and the side end face of the substrate which is closely fixed on the fixing surface 15 of the holding section 20 with being clamped by the liquid-leakage prevention jig 24 and the clamping frame 25, do not contact the reaction solution.
  • the deposition of the buffer layer begins earlier than a case where the substrate is heated after the substrate is immersed in the reaction solution. Therefore, time reduction of the film formation process can be achieved.
  • use of a metallic substrate as the substrate 10 results in a higher temperature rising rate of the substrate by heating, thereby further promoting the time reduction of the film formation process.
  • the substrate temperature is maintained at ⁇ by the heater 30, and the reaction solution temperature is maintained at T 2 by the reaction solution temperature control unit 40. It is believed that, after the substrate has been heated to ⁇ , the substrate temperature ⁇ is temporarily decreased by immersing the substrate in the reaction solution with the temperature lower than Ti, and the reaction solution temperature is temporarily increased. However, the temperature setting of the heater is maintained at Ti and the temperature setting of the temperature controlled by the reaction solution temperature control unit 40 is maintained at T 2 during the film formation.
  • the film formation time is not particularly limited. With a film formation time of, for example, 10 to 60 minutes, a layer well covering the under layer and having a sufficient thickness as the buffer layer can be formed, although it depends on the substrate temperature and the reaction solution temperature.
  • the heating temperature Ti [°C] of the substrate may be a predetermined temperature (constant temperature) in the range from 70 to 90 °C, and the controlled temperature T 2 of the reaction solution [°C] may be a predetermined temperature (constant temperature) of not more than 60 °C, or preferably not more than 40 °C.
  • ⁇ > 70 ⁇ T 2 +30 Ti is preferably 70 °C or more, and a difference between ⁇ and T 2 is preferably 30 °C or more.
  • the substrate heating temperature is higher than the controlled temperature of the reaction solution, it is believed that a temperature distribution is generated in the reaction solution in the reaction vessel 3 between the vicinity of the area where the substrate is held and areas apart from the substrate.
  • the temperature of the reaction solution at an area sufficiently apart from the substrate is measured as the reaction solution temperature.
  • the temperature controlling means 41 for the reaction solution is disposed at the bottom surface side of the reaction vessel 3 opposite from the vicinity of the liquid surface where the substrate is held, so that the temperature measuring unit 42 measures the temperature of the reaction solution in the vicinity of the bottom surface of the reaction vessel 3.
  • the substrate temperature of 70 °C or more raises the reaction solution temperature in the vicinity of the immersed substrate to allow sufficient deposition of the buffer layer on the substrate.
  • the reaction solution temperature lower than the substrate temperature, the reaction solution temperature at areas other than the area in the vicinity of the substrate is kept low, thereby suppressing the formation of particles (colloid) in the reaction solution.
  • the reaction solution temperature of 60 °C or less can significantly suppress the deposition reaction, and the reaction solution temperature of 40 °C or less results in almost no formation of particles (colloid) .
  • the particulate solid refers to a solid formed by aggregated particles having a primary particle size on the order of several tens to several hundreds nanometers. If a photoelectric conversion device is produced in a state where the particulate solids (secondary aggregates) having an equivalent circle diameter of around 1 um or more are adhering to the surface of the buffer layer, areas of the buffer layer to which the particulate solids adhere have higher resistance and hinder flow of electric current, and this may possibly result in degradation of performance of the photoelectric conversion device .
  • the particulate solids (secondary aggregates) adhering to the surface of the buffer layer may be peeled off, and the buffer layer may be peeled off at the same time. This may possibly result in degradation of performance of the photoelectric conversion device.
  • the reaction solution temperature set to be lower than the substrate temperature allows reduction of the formation of particles (colloid) compared to a case where the entire reaction solution is heated to a deposition temperature, thereby minimizing adhesion of the particulate solids to the surface of the deposited film.
  • the relatively high substrate temperature allows selective film deposition on the substrate.
  • coating the inner wall of the reaction vessel with Teflon (R) can enhance the effect of reducing the deposition on the inner wall of the reaction vessel.
  • the low reaction solution temperature of 60 °C or less, or 40 °C or less, allows more active reduction of the formation of particles (colloid) .
  • the formation of particles (colloid) promotes decrease of transmittance (decrease of transparency) of the reaction solution. Minimizing the formation of particles (colloid) , therefore, minimizes the decrease of transmittance (decrease of transparency) of the reaction solution. While the transparency of the reaction solution is high enough, the reaction solution can be repeatedly used, and this allows reducing the cost of forming the buffer layer.
  • the reaction solution is not stirred vigorously or not stirred at all .
  • the stirring may be achieved using a stirrer, or may be achieved by circulating the reaction solution or applying an ultrasonic wave to the reaction solution. Stirring the reaction solution promotes the formation of particles (colloid) in the reaction solution and increases the amount of particles (colloid) in the reaction solution. This increases the possibility of adhesion of the particulate solids to the surface of the deposited film.
  • Patent Document 1 mentioned above in the BACKGROUND ART section teaches, in the embodiment thereof, that the solution concentration is controlled to be constant by circulating the reaction solution. However, in a case where the reaction solution is circulated at a rate higher than a certain rate, the difference between the substrate temperature and the reaction solution temperature is reduced. In contrast, in the case where the reaction solution is not circulated, the difference between the substrate temperature and the reaction solution temperature can be maintained better, and this is more advantageous to achieve the selective deposition on the substrate.
  • the formation of the particulate solids is reduced compared to the case where the reaction solution is stirred.
  • the substrate holder holding the substrate is lifted out of the reaction solution, and the substrate having the buffer layer formed on the photoelectric conversion semiconductor layer is removed from the substrate holder .
  • the substrate held on the holder may be washed in this state with water to a certain extent.
  • the water is removed by a water removal mechanism, such as air knife.
  • the buffer layer is a Zn compound layer, i.e., a ZnS, Zn(S,0) or Zn(S,0, OH) layer
  • the buffer layer may be annealed at a temperature in the range from 150 °C to 230 °C, or preferably in the range from 170 °C to 210 °C, for 5 minutes to 60 minutes (some Zn compound layers require annealing to exhibit good performance, while some Zn compound layers do not) .
  • the annealing method is not particularly limited; however, heating with hot air using a commercially-available oven, electric furnace, vacuum oven, or the like, is preferred. By conducting the heat treatment in this manner, properties of the photoelectric conversion device, such as conversion efficiency, can be improved.
  • a relationship between the film formation time and the thickness of a formed film under predetermined conditions may be examined in advance, and the formation of the buffer layer may be ended when a certain film formation time to achieve a desired film thickness has been elapsed.
  • a relationship between the change of transmittance of the reaction solution and the thickness of a formed filmmaybe examined in advance, and the transmittance of the reaction solution may be measured in-situ to end the film formation based on decrease of the transmittance.
  • a relationship between the change of pH of the reaction solution and the thickness of a formed film may be examined in advance, and the pH of the reaction solution may be measured in-situ to end the film formation based on the amount of change of pH.
  • a relationship between the change of electric conductivity of the reaction solution and the thickness of a formed film may be examined in advance, and the electric conductivity of the reaction solution may be measured in-situ to end the film formation based on the amount of change of the electric conductivity.
  • the buffer layer is formed by a chemical bath deposition (CBD) process.
  • CBD chemical bath deposition
  • the "CBD process” is a process to deposit a thin metallic compound film on a substrate at an appropriate rate in a stable environment by forming a complex of a metal ion M using, as the reaction solution (chemical bath deposition solution) , a metal ion solution having a concentration and a pH that achieve a supersaturated condition by an equilibrium represented by the general formula below:
  • M represents a metallic element
  • L represents a ligand
  • m, n and i independently represent a positive number.
  • the buffer layer is not particularly limited; however, the buffer layer preferably contains a metal sulfide that contains Cd, Zn or In, such as CdS, ZnS, Zn(S,0) and/or Zn (S, 0, OH) , InS, In(S,0) and/or In(S,0, OH) .
  • the thickness of the buffer layer is preferably in the range from 5 ran to 2 urn, more preferably in the range from 10 to 200 nm or even more preferably in the range from 10 to 100 nm.
  • the chemical bath deposition solution (reaction solution) for depositing the buffer layer contains at least a metal (M) , such as Cd, Zn or In, and a sulfur source. Using this solution, the above-described buffer layer can be formed.
  • the sulfur source may be a compound containing sulfur, such as thiourea (CS(NH 2 )2) or thioacetamide (C2H5NS), or thiosemicarbazide, thiourethane, diethylamine, triethanolamine, or the like.
  • the concentration of each component of the reaction solution is not particularly limited as long as a desired buffer layer can be deposited.
  • a mixed solution containing the sulfur source, a Cd compound (such as cadmium sulfate, cadmium acetate, cadmium nitrate, cadmium chloride, or a hydrate thereof) , and an aqueous ammonia or ammonium salt (such as CH3COONH4 , H4CI, H 4 I, ( H 4 ) 2 S0, or the like) can be used as the reaction solution.
  • a mixed solution free of Cd such as a mixed solution containing the sulfur source, a Zn compound (such as zinc sulfate, zinc acetate, zinc nitrate, zinc chloride, zinc carbonate, or a hydrate thereof ) , and an aqueous ammonia or ammonium salt (examples thereof are the same as those listed above) can be used as the reaction solution.
  • a Zn compound such as zinc sulfate, zinc acetate, zinc nitrate, zinc chloride, zinc carbonate, or a hydrate thereof
  • an aqueous ammonia or ammonium salt examples thereof are the same as those listed above
  • the reaction solution preferably contains a citrate compound (trisodium citrate and/or a hydrate thereof) .
  • a citrate compound trisodium citrate and/or a hydrate thereof.
  • the CBD apparatus 1 of this embodiment in the case where the substrate fixing surface 21a of the substrate holder 20 is a curved surface, it is suitable for formation of the buffer layer on a flexible substrate.
  • the fixing surface 27a of the substrate holder 20' is a flat surface, as in the modification shown in FIG. 3, it is applicable to either of flexible and non-flexible substrates.
  • the CBD apparatus 1 shown in FIG. 1 is configured such that a square substrate is mounted one by one on the substrate holder 20, with assuming that the film formation is carried out in a batch process.
  • the method of forming a buffer layer of the invention is not limited to one that uses the apparatus shown in FIG.1, and is applicable to any CBD apparatus that can independently control the substrate temperature and the reaction solution temperature.
  • the method of forming a buffer layer of the invention is not limited to a batch process, and is also applicable to film formation carried out in a roll-to-roll process.
  • the substrate 10 used in the above-described embodiment includes at least the underlying substrate 11, the lower electrode (not shown) formed thereon, and the photoelectric conversion semiconductor layer 13, which forms the outermost surface.
  • the underlying substrate 11 may include a glass substrate, a metallic substrate, such as stainless steel, with an insulating film formed on the surface thereof, a resin substrate, such as polyimide, etc.
  • the substrate needs to be a flexible substrate, specifically, a flexible glass substrate, a flexible metallic substrate or a flexible polyimide substrate .
  • a non-flexible substrate such as a glass substrate having a thickness around 0.5 mm to 2 mm may also be used.
  • the substrate holder 20 includes the end face protective member, as in the CBD apparatus 1 of this embodiment, even if the underlying substrate 11 contains a component that dissolves in the CBD reaction solution, elution of such a component from the substrate does not occur.
  • the substrate contains a metal that may form a complex ion with a hydroxide ion, more particularly, when the substrate contains Al .
  • FIG. 4 shows a schematic sectional view of one embodiment of the photoelectric conversion device manufactured by the method of manufacturing a photoelectric conversion device of the invention.
  • elements shown in the drawing are not to scale.
  • the photoelectric conversion device shown in FIG. 4 includes a lower electrode (back side electrode) 12, a photoelectric conversion semiconductor layer 13, a buffer layer 14, a window layer 15, a transparent conductive layer (transparent electrode) 16 and an upper electrode (grid electrode) 17, which are sequentially formed on the substrate 11.
  • the method of manufacturing a photoelectric conversion device of the invention is characterized by that, in the method of manufacturing a photoelectric conversion device having a layered structure including at least the lower electrode 12, the photoelectric conversion semiconductor layer 13, the buffer layer 14 and the transparent conductive layer 16 formed on the substrate 11, the buffer layer is formed by the method of forming a buffer layer of the invention.
  • Methods for forming the layers other than the buffer layer are not particularly limited. Now, examples of the methods for forming the substrate and the individual layers are briefly described.
  • the substrate 11 may include: a glass substrate;
  • a metallic substrate such as stainless steel, having an insulating film formed on the surface thereof;
  • an anodized substrate having an anodized film mainly composed of AI2O 3 formed on at least one side of an Al base material mainly composed of Al;
  • a resin substrate such as polyimide.
  • the substrate may include a soda-lime glass (SLG) layer.
  • SSG soda-lime glass
  • the soda-lime glass layer serves to diffuse Na into the photoelectric conversion layer.
  • the photoelectric conversion layer contains Na, the photoelectric conversion efficiency is further improved.
  • the method of forming a buffer layer of the invention is applicable to either of flexible and non-flexible substrates .
  • the substrate fixing surface 21a of the substrate holder 20 is a curved surface, as shown as the CBD apparatus 1 of this embodiment, it is necessary to use a flexible substrate .
  • a substrate that contains a component that dissolves in the CBD reaction solution can be used.
  • the above-listed anodized substrates containing Al, which may form a complex ion with a hydroxide ion, can be used.
  • the main component of the lower electrode 12 is not particularly limited; however, it may preferably be Mo, Cr, W or a combination thereof, in particular, Mo, etc.
  • the thickness of the lower electrode 12 is not particularly limited; however, it may preferably be in the range from about 200 to 1000 nm.
  • the lower electrode 12 may, for example, be formed on the substrate using a sputtering process.
  • the main component of the photoelectric conversion semiconductor layer 13 is not particularly limited; however, in view of providing high photoelectric conversion efficiency, it may preferably be at least one compound semiconductor having a chalcopyrite structure, more preferably, at least one compound semiconductor containing a group lb element, a group IIlb element and a group VIb element.
  • the main component of the photoelectric conversion semiconductor layer 13 may preferably be at least one compound semiconductor containing:
  • At least one group Illb element selected from the group consisting of Al, Ga and In, and
  • Examples of the compound semiconductor include:
  • Examples of the compound semiconductor may further include Cu 2 ZnSnS, Cu 2 ZnSnSe 4 , Cu 2 ZnSn (S, Se) 4 , CdTe, (Cd, Zn) Te, etc.
  • the thickness of the photoelectric conversion semiconductor layer 13 is not particularly limited; however, it may preferably be in the range from 1.0 to 4.0 urn, or particularly preferably be in the range from 1.5 to 3.5 urn.
  • the method for forming the photoelectric conversion semiconductor layer 13 is not particularly limited, and the photoelectric conversion semiconductor layer 13 may be formed by a vacuum deposition process, a sputtering process, a MOCVD process, or the like.
  • the buffer layer 14 is formed by the method of forming a buffer layer of the invention as described above.
  • the conductivity type of the buffer layer 14 is not particularly limited; however, n-type is preferable.
  • the thickness of the buffer layer 14 is not particularly limited; however, it may preferably be in the range from 5 nm to 2 um, more preferably be in the range from 10 to 200 nm, or even more preferably be in the range from 10 to 100 nm.
  • the details of the buffer layer are as described above.
  • the window layer 15 is an intermediate layer serves to take in light.
  • the composition of the window layer 15 is not particularly limited; however, it may preferably be i-ZnO, etc.
  • the thickness of the window layer 15 is not particularly limited; however, it may preferably be in the range from 10 nm to 2 um, or more preferably be in the range from 15 to 200 nm.
  • the method for forming the window layer 15 is not particularly limited; however, a sputtering process or a MOCVD process is suitable. Since the buffer layer 14 is formed by the liquid phase process, it may be preferable to use a liquid phase process in view of simplifying the manufacturing process.
  • the window layer is optional, i.e., the photoelectric conversion device may not include the window layer 15.
  • the transparent conductive layer 16 serves to take in light and also serves as an electrode, which forms a pair with the lower electrode 12 and an electric current generated at the photoelectric conversion semiconductor layer 13 flows therethrough.
  • the composition of the transparent conductive layer 16 is not particularly limited; however, it may preferably be n-ZnO, such as ZnO:Al, ZnO:Ga, ZnO:B, etc.
  • the thickness of the transparent conductive layer 16 is not particularly limited; however, it may preferably be in the range from 50 nm to 2 urn.
  • the method for forming the transparent conductive layer 16 is not particularly limited; however, a sputtering process or a MOCVD process is suitable, as with the window layer. In view of simplifying the manufacturing process, use of a liquid phase process may also be preferable.
  • the main component of the upper electrode 17 is not particularly limited; however, it may be Al, etc.
  • the thickness of the upper electrode 17 is not particularly limited; however, it may preferably be in the range from 0.1 to 3 urn.
  • the upper electrode is provided at a cell that serves as a power output end among the cells connected in series.
  • the photoelectric conversion device 5 manufactured by the manufacturing method of this embodiment has the above-described configuration.
  • the ' photoelectric conversion device 5 is preferably applicable to applications, such as solar batteries .
  • a solar battery can be formed by attaching a cover glass, a protective film, etc., to the photoelectric conversion device 5, as necessary.
  • the photoelectric conversion device manufactured according to the manufacturing method of the invention is applicable not only to solar batteries but also to other applications, such as CCDs.
  • the substrate includes the lower electrode and the photoelectric conversion semiconductor layer 13, which are formed on the underlying substrate 11.
  • the substrate used was an anodized substrate including an aluminum anodized film (AAO) formed on an Al surface of a composite base material formed by 100 urn-thick stainless steel (SUS) and 30 um-thickAl, with a soda lime glass (SLG) layer, a Mo electrode layer, and the photoelectric conversion semiconductor layer sequentially formed on the AAO surface.
  • AAO aluminum anodized film
  • SLG soda lime glass
  • Mo electrode layer a Mo electrode layer
  • the photoelectric conversion semiconductor layer sequentially formed on the AAO surface.
  • the SLG layer and the Mo electrode layer were formed by sputtering, and a Cu (Ino.7Gao.3) Se2 layer was formed as the photoelectric conversion semiconductor layer by a three stage process.
  • the thicknesses of these layers were as follows: SUS (100 um) , Al (30 urn), AAO (20 urn), SLG (0.2 um) , Mo (0.8 um) and CIGS (1.8 um) .
  • the size of the substrate was 10 cm ⁇ 10 cm.
  • reaction vessel containing a 10% aqueous KCN solution was prepared, and the surface of the CIGS layer, which is the substrate surface on which the buffer layer is formed, was immersed in the solution for 3 minutes at room temperature to remove impurities from the surface of the CIGS layer. After the substrate was removed from the solution, the substrate was sufficiently washed with water.
  • An aqueous zinc sulfate solution (0.18 [M] ) was prepared as an aqueous solution (I) of a component (Z)
  • an aqueous thiourea solution (0.30 [M] thiourea) was prepared as an aqueous solution (II) of a component (S)
  • an aqueous trisodium citrate solution (0.18 [M] ) was prepared as an aqueous solution (III) of a component (C)
  • an aqueous ammonia (0.30 [M] ) was prepared as an aqueous solution (IV) of a component (N) .
  • the same volume of the aqueous solutions I, II and III were mixed to form a mixed solution containing 0.06 [M] zinc sulfate, 0.10 [M] thiourea and 0.06 [M] trisodium citrate, and the same volume of the mixed solution and the 0.30 [M] aqueous ammonia were mixed to provide the CBD solution (reaction solution) .
  • the aqueous solutions (I) to (IV) were mixed, the aqueous solution (IV) was added lastly. In order to provide a transparent reaction solution, it is important to add the aqueous solution (IV) lastly.
  • the thus obtained reaction solution was filtered using a filter having a mesh size of 0.22 urn.
  • the pH of the finally obtained reaction solution was 10.3.
  • this reaction solution I is used, a buffer layer formed by a Zn(S,0) film is obtained.
  • aqueous CdS0 4 solution Predetermined amounts of an aqueous CdS0 4 solution, an aqueous thiourea solution and an aqueous ammonia solution were mixed to prepare a CBD solution (reaction solution II) containing 0.0015M CdSCv 0.05M thiourea and 1.5M ammonia .
  • the pH of the finally obtained reaction solution II was 12.0.
  • this reaction solution II When this reaction solution II is used, a buffer layer formed by a CdS film is obtained.
  • the prepared substrate was set on the substrate holding section of the CBD apparatus shown in FIG. 1.
  • the heater was turned on to heat the substrate to 90 °C.
  • the substrate holding section was brought down to immerse the substrate in the reaction solution I with the reaction solution temperature controlled to 40 °C, and the buffer layer was deposited on the surface of the photoelectric conversion semiconductor layer.
  • the deposition time was 30 minutes. During the deposition period, the heating of the substrate with the heater (the set temperature was 90 °C) and the control of the reaction solution temperature (the set temperature was 40 °C) were continued.
  • Example 1-2
  • Example 1-2 the CBD apparatus shown in FIG. 1 including the substrate holding section 20' shown in FIG. 3, which has the flat substrate fixing surface, was used.
  • the substrate was immersed in the reaction solution with the fixing surface inclined from the horizontal plane 2a, as shown by the dashed lines in FIG.3. Except these points, deposition of the buffer layer was conducted in the same manner as in Example 1-1.
  • Example 1-3 the CBD apparatus shown in FIG. 1 including the substrate holding section 20' shown in FIG. 3, which has the flat substrate fixing surface, was used.
  • the substrate was immersed in the reaction solution with the fixing surface inclined from the horizontal plane 2a, as shown by the dashed lines in FIG.3. Except these points, deposition of the buffer layer was conducted in the same manner as in Example 1-1.
  • Example 1-3 the CBD apparatus shown in FIG. 1 including the substrate holding section 20' shown in FIG. 3, which has the flat substrate fixing surface, was used.
  • the substrate was immersed in the reaction solution with the fixing surface inclined from the horizontal plane 2a, as shown by the dashed lines in FIG.
  • Example 1-3 the same apparatus as in Example 1-2 was used. However, the substrate was immersed in the reaction solution with the fixing surface kept in parallel with the horizontal plane 2a. Except these points, deposition of the buffer layer was conducted in the same manner as in Examples 1-1 and 1-2.
  • the CBD apparatus 100 includes: a reaction vessel 103, which can contain the reaction solution 2 (the reaction solution I in this example) ; an opening 103a, which is smaller than the size of the substrate 10, formed in the wall surface of the reaction vessel 103; a substrate holding section (substrate holder) 104 for holding the substrate 10 on the outer side wall surface of the reaction vessel 103 at a position corresponding to the opening 103a, such that the entire opening 103a is covered with the substrate 10; a reaction solution temperature control unit 110; and a substrate heating control unit 120.
  • a reaction vessel 103 which can contain the reaction solution 2 (the reaction solution I in this example) ; an opening 103a, which is smaller than the size of the substrate 10, formed in the wall surface of the reaction vessel 103; a substrate holding section (substrate holder) 104 for holding the substrate 10 on the outer side wall surface of the reaction vessel 103 at a position corresponding to the opening 103a, such that the entire opening 103a is covered with the substrate 10; a reaction
  • the substrate holder 104 includes a back plate 106 (which also serves as a part of a constant-temperature water circulation path, which will be described later) that can uniformly press the entire back side of the substrate 10, and screw members 107 that can press the back plate 106 toward the opening 103a.
  • This substrate holder 104 holds the substrate parallel to the side wall surface of the reaction vessel.
  • the reaction solution temperature control unit 110 includes a constant-temperature water circulation path 112 for controlling the reaction solution temperature, which is disposed externally to the reaction vessel 103 and circulates constant-temperature water 111 to heat or cool the reaction solution 2 from outside the reaction vessel 103, and a thermostatic chamber 113 for maintaining the constant temperature of the water.
  • the substrate heating control unit 120 includes a constant-temperature water circulation path 122 for heating the substrate, which is disposed at the back side of the substrate and circulates constant-temperature water 121 to heat the substrate 10 from the back side of the substrate, and a thermostatic chamber 123 for maintaining the constant temperature of the water. That is, the CBD apparatus 100 includes a mechanism (the reaction solution temperature control unit 110) for controlling the reaction solution temperature introduced into the CBD apparatus at a predetermined temperature separately (independently) from a mechanism (the substrate heating control unit 120) for heating the back side of the substrate, so that the reaction solution temperature and the substrate temperature can be controlled independently from each other.
  • the reaction solution temperature control unit 110 for controlling the reaction solution temperature introduced into the CBD apparatus at a predetermined temperature separately (independently) from a mechanism (the substrate heating control unit 120) for heating the back side of the substrate, so that the reaction solution temperature and the substrate temperature can be controlled independently from each other.
  • Example 1-4 the substrate was set on the substrate holder and heated to 90 °C. Then, 15 minutes after the start of heating of the substrate, the reaction solution I with the temperature thereof controlled to 40 °C was poured into the reaction vessel, and deposition of the buffer layer was conducted for 30 minutes. During the buffer layer deposition period, a state where the constant-temperature water 121 at 90 °C and the constant-temperature water 122 at 40 °C were circulated was maintained by the substrate heating control unit 120 and the reaction solution temperature control unit 110, respectively.
  • Example 1-5 the same CBD apparatus as in Example 1-1 was used. Deposition of the buffer layer was conducted in the same manner as in Examples 1-1 except that the reaction solution II was used, the substrate heating temperature was 80 °C, and the film formation time was 4 minutes.
  • the prepared reaction solution 2 (the reaction solution I in this example) was poured into a reaction vessel 150 formed by a glass beaker, as schematically shown in FIG. 6. Then, in a state where the substrate (substrate 10) was leaned against the inner wall of the reaction vessel with the surface on which the film was to be deposited facing down, the reaction vessel 150 was immersed in constant-temperature water 156 in a thermostatic chamber 155 to heat the reaction solution to 90 °C, and deposition of the buffer layer was conducted for 60 minutes after the reaction solution was heated to 90 °C. In Comparative Example 1-1, the substrate was heated via the reaction solution.
  • the thickness was measured at seven points from each SEM image to measure the thickness at the total of 35 points, and an average film thickness and a standard deviation of the film thicknesses were calculated. Evaluation of Number of Particles Adhering to Film Surface
  • Presence of aggregations of particles having a primary particle size on the order of several tens to several hundreds nanometers adhering to the film surface (aggregations found when the film surface was observed from right above) in a field of view of 100 urn x 100 urn was evaluated according to the following criteria.
  • Good (A) The number of aggregations having an equivalent circle diameter of 3 um or more was at most three.
  • Acceptable (B) The number of aggregations having an equivalent circle diameter of 3 um or more was in the range from 4 to 10.
  • Bad (C) The number of aggregations having an equivalent circle diameter of 3 um or more was 11 or more.
  • the presence of the film can be visually checked based on interference thereof even when the film is a very thin film having a thickness of less than 100 run. Therefore, first, areas without the film were checked by visual evaluation. The result of the visual evaluation was evaluated according to the following criteria.
  • Acceptable (B) Areas without the film occupied less than 5% of the area of the substrate; however, not 0.
  • the amount of Al [ppm] eluted in the reaction solution was measured after the film formation.
  • Examples 1-1 to 1-4 where the reaction solution temperature was set lower than the substrate temperature, good films with a very small number of adhering particles (colloid) were obtained. Further, the transmittance of the reaction solution was 80% or more in all the Examples 1-1 to 1-4, and this clearly means that the formation of particles (colloid) was suppressed.
  • the standard deviation of the film thickness in the examples of the invention tended to be somewhat smaller. It is expected that the effect of uniformizing the film thickness of the invention will be more apparent when a thicker buffer layer is formed.
  • the inner wall of the reaction vessel used in Examples 1-1 to 1-5 was coated with Teflon (R) , resulting in very small adhesion of the deposited film on the inner wall.
  • the reaction vessel used was a glass beaker, which was not coated with Teflon (R) , resulting in heavy adhesion of the deposited film on the inner wall.
  • the substrate includes the lower electrode and the photoelectric conversion semiconductor layer 13, which are formed on the underlying substrate 11.
  • the following two types of substrates were prepared.
  • a substrate I used was an anodized substrate including an aluminum anodized film ( ⁇ ) formed on an Al surface of a composite base material formed by 100 um-thick stainless steel (SUS) and 30 um-thick Al,- with a soda lime glass (SLG) layer, a Mo electrode layer, and the photoelectric conversion semiconductor layer sequentially formed on the AAO surface.
  • SLG layer and the Mo electrode layer were formed by sputtering, and a Cu (In 0 .7Gao.3) Se 2 layer was formed as the photoelectric conversion semiconductor layer by a three stage process.
  • the thicknesses of these layers were as follows: SUS (100 um) , Al (30 um) , AAO (20 um) , SLG (0.2 um) , Mo (0.8 um) and CIGS (1.8 um) .
  • the size of the substrate was 10 cm * 10 cm.
  • a substrate II used was a soda lime glass (SLG) substrate with a Mo electrode layer, on which a CIGS layer was formed.
  • the Mo lower electrode having a thickness of 0.8 um was formed on the soda lime glass (SLG) substrate by sputtering, and the Cu (In 0 .7Gao. 3 ) Se 2 layer having a thickness of 1.8 um was formed on the Mo lower electrode using a three stage process.
  • the size of the substrate II was 3 cm ⁇ 3 cm.
  • reaction vessel containing a 10% aqueous KCN solution was prepared, and the surface of the CIGS layer, which is the substrate surface on which the buffer layer is formed, was immersed in the solution for 3 minutes at room temperature to remove impurities from the surface of the CIGS layer. After the substrate was removed from the solution, the substrate was sufficiently washed with water.
  • An aqueous zinc sulfate solution (0.18 [M] ) was prepared as an aqueous solution (I) of a component (Z)
  • an aqueous thiourea solution (0.30 [M] thiourea) was prepared as an aqueous solution (II) of a component (S)
  • an aqueous trisodium citrate solution (0.18 [M] ) was prepared as an aqueous solution (III) of a component (C)
  • an aqueous ammonia (0.30 [M] ) was prepared as an aqueous solution (IV) of a component (N) .
  • the same volume of the aqueous solutions I, II and III were mixed to form a mixed solution containing 0.06 [M] zinc sulfate, 0.10 [M] thiourea and 0.06 [M] trisodium citrate, and the same volume of the mixed solution and the 0.30 [M] aqueous ammonia were mixed to provide the CBD solution (reaction solution) .
  • the aqueous solutions (I) to (IV) were mixed, the aqueous solution (IV) was added lastly. In order to provide a transparent reaction solution, it is important to add the aqueous solution (IV) lastly.
  • the thus obtained reaction solution was filtered using a filter having a mesh size of 0.22 urn.
  • the pH of the finally obtained reaction solution was 10.3.
  • Zn(S,0) film was formed as the buffer layer under conditions of examples and comparative examples.
  • the substrate was heated in advance to the temperature Ti, and the substrate was immersed in the reaction solution at the temperature T2, where the condition: the substrate heating temperature Ti > the controlled temperature of the reaction solution T 2 was satisfied, to form the buffer layer.
  • Example 2-1 the CBD apparatus 1 shown in FIG. 1 was used.
  • the substrate I was set on the substrate holder and heated to 90 °C. 15 minutes after the start of heating, the substrate was immersed in the reaction solution with the temperature controlled to 40 °C, and deposition of the buffer layer was conducted for 30 minutes .
  • the CBD apparatus 100 includes: a reaction vessel 103, which can contain the reaction solution 2; an opening 103a, which is smaller than the size of the substrate 10, formed in the wall surface of the reaction vessel 103; a substrate holding section (substrate holder) 104 for holding the substrate 10 on the outer side wall surface of the reaction vessel 103 at a position corresponding to the opening 103a, such that the entire opening 103a is covered with the substrate 10; a reaction solution temperature control unit 110; and a substrate heating control unit 120.
  • the substrate holder 104 includes a back plate 106 (which also serves as a part of a constant-temperature water circulation path, which will be described later) that can uniformly press the entire back side of the substrate 10, and screw members 107 that can press the back plate 106 toward the opening 103a.
  • a back plate 106 (which also serves as a part of a constant-temperature water circulation path, which will be described later) that can uniformly press the entire back side of the substrate 10, and screw members 107 that can press the back plate 106 toward the opening 103a.
  • the reaction solution temperature control unit 110 includes a constant-temperature water circulation path 112 for controlling the reaction solution temperature, which is disposed externally to the reaction vessel 103 and circulates constant-temperature water 111 to heat or cool the reaction solution 2 from outside the reaction vessel 103, and a thermostatic chamber 113 for maintaining the constant temperature of the water.
  • the substrate heating control unit 120 includes a constant-temperature water circulation path 122 for heating the substrate, which is disposed at the back side of the substrate and circulates constant-temperature water 121 to heat the substrate 10 from the back side of the substrate, and a thermostatic chamber 123 for maintaining the constant temperature of the water. That is, the CBD apparatus 100 includes a mechanism (the reaction solution temperature control unit 110) for controlling the reaction solution temperature introduced into the CBD apparatus at a predetermined temperature separately (independently) from a mechanism (the substrate heating control unit 120) for heating the back side of the substrate, so that the reaction solution temperature and the substrate temperature can be controlled independently from each other.
  • the reaction solution temperature control unit 110 for controlling the reaction solution temperature introduced into the CBD apparatus at a predetermined temperature separately (independently) from a mechanism (the substrate heating control unit 120) for heating the back side of the substrate, so that the reaction solution temperature and the substrate temperature can be controlled independently from each other.
  • Example 2-2 the substrate II was set on the substrate holder and heated to 90 °C. 15 minutes after the start of heating of the substrate II, the reaction solution with the temperature thereof controlled to 40 °C was poured into the reaction vessel, and deposition of the buffer layer was conducted for 30 minutes.
  • Example 2-3 the substrate II was set on the substrate holder and heated to 90 °C. 15 minutes after the start of heating of the substrate II, the reaction solution with the temperature thereof controlled to 40 °C was poured into the reaction vessel, and deposition of the buffer layer was conducted for 30 minutes.
  • Example 2-2 The same CBD apparatus as that used in Example 2-2 was used.
  • Example 2-1 Deposition of the buffer layer was conducted in the same manner as in Example 2-2 except that the controlled temperature of the reaction solution T 2 was 20 °C and the deposition time was 120 minutes. Comparative Example 2-1
  • Example 2-1 The same CBD apparatus as that used in Example 2-1 was used, except that the heater for heating the substrate was not used.
  • the reaction pot 130 includes : a reaction vessel 133, which can contain the reaction solution 2; an opening 133a which is formed in the wall of the reaction vessel 133 and is smaller than the size of the substrate; and a substrate holding section (substrate holder) 134 for holding the substrate 10 on the outer side wall surface of the reaction vessel 133 at a position corresponding to the opening 133a, such that the entire opening 133a is covered with the substrate 10.
  • the substrate holder 134 includes a back plate 136 that can uniformly press the entire back side of the substrate 10, and a screw member 137 that can press the back plate 136 toward the opening 133a.
  • the prepared reaction solution 2 was poured into a SUS reaction vessel 150, as schematically shown in FIG. 6. Then, in a state where the substrate I (substrate 10) was leaned against the inner wall of the reaction vessel with the surface onwhich the filmwas to be deposited facing down, the reaction vessel 150 was immersed in the constant-temperature water 156 in the thermostatic chamber 155, and deposition of the buffer layer was conducted for 60 minutes. In this method, the substrate I was heated via the reaction solution.
  • Example 2-1 The same CBD apparatus as in Example 2-1 was used.
  • Example 2-5 Deposition of the buffer layer was conducted under the same conditions as in Example 2-1 except that the controlled temperature of the reaction solution T 2 was 90 °C, and the substrate heating temperature and the control temperature were the same temperature. Comparative Example 2-5
  • Example 2-1 The same CBD apparatus as in Example 2-1 was used.
  • Deposition of the buffer layer was conducted under the same conditions as in Example 2-1 except that the heating of the substrate was started after the substrate was immersed in the reaction solution.
  • Example 2-2 The same CBD apparatus as in Example 2-2 was used.
  • the substrate II was set on the substrate holder and heated to 40 °C. At the same time, the reaction solution with the temperature thereof controlled to 40 °C was poured into the reaction vessel, and deposition of the buffer layer was conducted for 30 minutes. The heating of the substrate holding section was started at the same time when the substrate was immersed in the reaction solution. Evaluation of Film Thickness
  • Acceptable (B) The number of aggregations having an equivalent circle diameter of 3 urn or more was in the range from 4 to 10.
  • the transmittance of the reaction solution after the reaction was measured in a wavelength range from 200 nm to 800 nm.
  • the value of transmittance at the wavelength of 550 nm is shown in Table 2.
  • Example 2-3 where the controlled temperature of the reaction solution was 20 °C, the transmittance of the reaction solution after the film formation, i.e., the effect of suppressing the formation of particles (colloid) , was remarkably higher than that in Examples 2-1 and 2-2, where the controlled temperature of the reaction solution was 40 °C, whereas the deposition rate in Example 2-3 was lower than that in Examples 2-1 and 2-2.

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Abstract

Selon l'invention, une couche tampon d'un dispositif de conversion photoélectrique ayant une qualité supérieure est obtenue à de plus faibles coûts. L'invention porte sur un appareil de dépôt en bain chimique (1) comprenant : un récipient à réaction (3) destiné à contenir une solution réactionnelle (2) pour un dépôt en bain chimique pour former un film sur une surface (10a) d'un substrat (10) ; une section de support de substrat (20) destinée à porter le substrat (10) de façon à ce qu'au moins la surface (10a) du substrat (10) soit en contact avec la solution réactionnelle (2), la section de support de substrat comprenant une surface de fixation (21a) constituée d'acier inoxydable sur laquelle un côté arrière du substrat (10) est étroitement fixé ; un dispositif de chauffage (30) disposé au niveau d'un côté arrière de la surface de fixation (21a), le dispositif de chauffage chauffant le substrat (10) à partir du côté arrière du substrat ; et une unité de régulation de température de solution réactionnelle (40) pour la régulation de la température de la solution réactionnelle (2) dans le récipient à réaction (3).
PCT/JP2012/073002 2011-09-05 2012-09-03 Appareil de dépôt en bain chimique, procédé de formation de couche tampon et procédé de fabrication de dispositif de conversion photoélectrique WO2013035876A1 (fr)

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CN201280052384.0A CN103906857A (zh) 2011-09-05 2012-09-03 化学浴沉积设备、形成缓冲层及制造光电转换装置的方法
US14/196,338 US20140186988A1 (en) 2011-09-05 2014-03-04 Chemical bath deposition apparatus, method of forming buffer layer and method of manufacturing photoelectric conversion device

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JP2012169379A JP2013070032A (ja) 2011-09-05 2012-07-31 バッファ層の製造方法および光電変換素子の製造方法

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EP2784179A1 (fr) * 2013-03-25 2014-10-01 Samsung SDI Co., Ltd. Appareil de dépôt et procédé de recyclage de solution
EP2804220A3 (fr) * 2013-05-16 2015-01-14 Samsung SDI Co., Ltd. Procédé et dispositif de fabrication de cellule solaire à film mince et cellule solaire à film mince comprenant une couche tampon fabriquée par ce procédé
EP2784826A3 (fr) * 2013-03-27 2015-01-14 Samsung SDI Co., Ltd. Procédé de fabrication de cellule solaire à film mince et cellule solaire à film solaire fabriquée par le procédé
CN104762611A (zh) * 2015-04-09 2015-07-08 深圳先进技术研究院 化学浴沉积设备和制备ZnS薄膜的方法
EP3059277A1 (fr) * 2015-02-23 2016-08-24 Enthone, Incorporated Composition d'inhibiteur pour racks lors de l'utilisation de gravures exemptes de chrome sur des processus plastiques
CN114420789A (zh) * 2021-12-30 2022-04-29 南京同宁新材料研究院有限公司 太阳能薄膜电池的镀膜装置及镀膜方法

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2784179A1 (fr) * 2013-03-25 2014-10-01 Samsung SDI Co., Ltd. Appareil de dépôt et procédé de recyclage de solution
EP2784826A3 (fr) * 2013-03-27 2015-01-14 Samsung SDI Co., Ltd. Procédé de fabrication de cellule solaire à film mince et cellule solaire à film solaire fabriquée par le procédé
EP2804220A3 (fr) * 2013-05-16 2015-01-14 Samsung SDI Co., Ltd. Procédé et dispositif de fabrication de cellule solaire à film mince et cellule solaire à film mince comprenant une couche tampon fabriquée par ce procédé
EP3059277A1 (fr) * 2015-02-23 2016-08-24 Enthone, Incorporated Composition d'inhibiteur pour racks lors de l'utilisation de gravures exemptes de chrome sur des processus plastiques
CN104762611A (zh) * 2015-04-09 2015-07-08 深圳先进技术研究院 化学浴沉积设备和制备ZnS薄膜的方法
CN114420789A (zh) * 2021-12-30 2022-04-29 南京同宁新材料研究院有限公司 太阳能薄膜电池的镀膜装置及镀膜方法
CN114420789B (zh) * 2021-12-30 2023-11-03 南京同宁新材料研究院有限公司 太阳能薄膜电池的镀膜装置及镀膜方法

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