US20110303281A1 - Method for manufacturing thin film compound solar cell - Google Patents
Method for manufacturing thin film compound solar cell Download PDFInfo
- Publication number
- US20110303281A1 US20110303281A1 US13/202,678 US201013202678A US2011303281A1 US 20110303281 A1 US20110303281 A1 US 20110303281A1 US 201013202678 A US201013202678 A US 201013202678A US 2011303281 A1 US2011303281 A1 US 2011303281A1
- Authority
- US
- United States
- Prior art keywords
- surface electrode
- layer
- etching
- solar cell
- thin film
- 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.)
- Abandoned
Links
- 150000001875 compounds Chemical class 0.000 title claims abstract description 117
- 239000010409 thin film Substances 0.000 title claims abstract description 69
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims description 120
- 238000005530 etching Methods 0.000 claims abstract description 62
- 239000004065 semiconductor Substances 0.000 claims abstract description 55
- 239000000463 material Substances 0.000 claims abstract description 38
- 239000000758 substrate Substances 0.000 claims abstract description 38
- 239000012779 reinforcing material Substances 0.000 claims abstract description 32
- 229920001721 polyimide Polymers 0.000 claims description 44
- 238000000137 annealing Methods 0.000 claims description 22
- 239000004642 Polyimide Substances 0.000 claims description 20
- 229920005575 poly(amic acid) Polymers 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- 230000008595 infiltration Effects 0.000 claims description 4
- 238000001764 infiltration Methods 0.000 claims description 4
- 239000013078 crystal Substances 0.000 claims description 3
- 239000002243 precursor Substances 0.000 claims description 3
- 238000005245 sintering Methods 0.000 claims description 3
- 239000010408 film Substances 0.000 abstract description 110
- 230000001070 adhesive effect Effects 0.000 abstract description 15
- 238000010030 laminating Methods 0.000 abstract description 5
- 239000010410 layer Substances 0.000 description 150
- 230000001681 protective effect Effects 0.000 description 53
- 239000002585 base Substances 0.000 description 32
- 238000000059 patterning Methods 0.000 description 12
- 230000015572 biosynthetic process Effects 0.000 description 11
- 229920002120 photoresistant polymer Polymers 0.000 description 11
- 239000000853 adhesive Substances 0.000 description 9
- 229920005989 resin Polymers 0.000 description 9
- 239000011347 resin Substances 0.000 description 9
- 238000000926 separation method Methods 0.000 description 8
- 239000007772 electrode material Substances 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 6
- 239000003960 organic solvent Substances 0.000 description 6
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 230000008602 contraction Effects 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000002344 surface layer Substances 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 238000004528 spin coating Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229920002799 BoPET Polymers 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000004063 acid-resistant material Substances 0.000 description 1
- 239000002313 adhesive film Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 238000009281 ultraviolet germicidal irradiation Methods 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/036—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
- H01L31/0392—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/036—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
- H01L31/0392—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
- H01L31/03926—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 comprising a flexible substrate
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
- H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
- H01L31/0687—Multiple junction or tandem solar cells
- H01L31/06875—Multiple junction or tandem solar cells inverted grown metamorphic [IMM] multiple junction solar cells, e.g. III-V compounds inverted metamorphic multi-junction cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
- H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
- H01L31/0693—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells the devices including, apart from doping material or other impurities, only AIIIBV compounds, e.g. GaAs or InP solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
- H01L31/1864—Annealing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1892—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof methods involving the use of temporary, removable substrates
-
- 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
- Y02E10/544—Solar cells from Group III-V materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to a method for manufacturing a thin film compound solar cell having a cell main body in which at least one PN junction is formed by a plurality of compound semiconductor layers, each having a different chemical composition.
- a conventional thin film compound solar cell is configured such that a surface electrode is provided on a light receiving surface of a cell main body formed by laminating a plurality of compound semiconductor layers, and such that a rear surface electrode is provided on the surface opposite to the light receiving surface of the cell main body.
- the thin film compound solar cell is manufactured as follows. In process A 1 shown in FIG. 24 , an etching-stop layer 102 , a base layer 103 , an emitter layer 104 , and a contact layer 105 respectively formed by compound semiconductor layers are laminated in this order on a substrate 101 , so that a cell main body is formed.
- a protective film such as a photoresist
- a protective film is applied on the surface of the contact layer 105 , and the region of the protective film, which region is patterned by exposure, is etched.
- the contact layer 105 is patterned by contact layer etching.
- the applied resist is removed after the completion of the patterning.
- a photoresist is again applied for formation of a surface electrode, and a protective film is formed.
- a protective film opening section is formed by patterning the photoresist by exposure so that the protective film opening section is included in the region of the contact layer 105 formed by the preceding process.
- the photoresist is removed, so that a surface electrode 106 is selectively formed only in the protective film opening section.
- the region of the surface electrode can be patterned so as to be included in the region of the contact layer formed by the preceding process.
- the surface electrode 106 is annealed at a temperature of about 350° C. in order to reduce the component of contact resistance between the surface electrode 106 and the contact layer 105 and to increase the adhesive force between the surface electrode 106 and the contact layer 105 .
- the protective film is patterned by exposure so as to define a cell formation region corresponding to a predetermined shape (chip shape) of a solar cell element.
- a protective film opening section is formed, so that the opening section is mesa-etched.
- the solar cell element having the predetermined shape (chip shape) is separated by mechanical means, such as dicing.
- a transparent resin such as silicone resin
- a transparent surface film 107 is bonded onto the transparent resin.
- the thin film compound solar cell and the surface film 107 are bonded to each other via the resin, so that the surface film 107 serves as a base material of the thin film compound solar cell.
- a reinforcing material 108 such as glass or sapphire, is bonded via wax on the side of the light receiving surface of the solar cell element, to which side the surface film 107 is bonded.
- the solar cell element to which the reinforcing material 108 is bonded, is immersed in an etchant. Since the etching is stopped at the etching-stop layer 102 , only the substrate 101 can be removed so that only the cell main body is left. Thereby, the substrate 101 is separated from the compound semiconductor layers, so that the solar cell element exhibits its flexibility.
- an electrode material is vapor-deposited on the exposed rear surface of the compound semiconductor layer, so that a rear surface electrode 109 is formed.
- the thin film compound solar cell manufactured as described above has the structure in which the surface film as the base material is bonded to the light receiving surface of the cell main body with a PN junction formed therein.
- the surface film is bonded on the side of the light receiving surface, and hence high transparency is required for the surface film so as to prevent the conversion efficiency of the solar cell element from being impaired.
- the high transparency film generally has low temperature resistance.
- the process is performed such that, after the surface film is bonded to the solar cell element, the substrate is removed and the rear surface electrode is formed. After the formation of the rear surface electrode, it is necessary to anneal the rear surface electrode in order to reduce the component of contact resistance between the rear surface electrode and the compound semiconductor layer, and in order to increase the adhesive force between the rear surface electrode and the compound semiconductor layer.
- the annealing temperature is higher than the heat-resistant temperature of the surface film, and hence the rear surface electrode cannot be annealed in the state where the surface film is bonded to the solar cell element. Therefore, there is a problem that the rear surface electrode is separated from the compound semiconductor layer.
- the resin used to bond the compound semiconductor layer to the surface film is also exposed to the organic solvent at the same time.
- the exposed resin penetrates into the interface between the surface film and the resin, or into the interface between the compound semiconductor layer and the resin, so as to make the surface film liable to be separated from the compound semiconductor layer.
- the process for removing the substrate by the etchant is performed after a metallic ribbon for establishing electrical connection is welded to the solar cell element.
- the etchant for etching the substrate it is necessary to use hydrofluoric acid, and the like, depending on the substrate material.
- hydrofluoric acid reacts with the metallic ribbon to corrode the metallic ribbon.
- the exposed metallic ribbon is required to be protected by being covered with an acid resistant material. This results in a problem that the number of processes is increased.
- a method for manufacturing the compound solar cell described in Patent Document 1 includes: forming the rear surface electrode on the cell main body; attaching a support plate on the rear surface electrode; separating the substrate from the cell main body to expose the surface of the cell main body; forming the surface electrode on the exposed surface of the cell main body; and then removing the support plate.
- the rear surface electrode is formed first. For this reason, after the rear surface electrode is annealed, the surface film can be bonded.
- the surface film as the base material is not provided, and hence the problem of separation of the surface film does not occur.
- the structure of the solar-battery cell described in Patent Document 1 has a problem that, since the structure is configured only by the semiconductor epitaxial layer and the rear surface electrode, the epitaxial layer is easily broken when an external force due to bending, or the like, is applied to the structure. Further, in the structure configured only by the semiconductor epitaxial layer and the rear surface electrode, the warpage of the solar-battery cell cannot be controlled.
- an object of the present invention is to provide a method for manufacturing a thin film compound solar cell which can improve the adhesive property of the electrode even when provided with the base material and which can withstand the external force without the separation of the base material.
- the present invention provides a method for manufacturing a thin film compound solar cell having a cell main body in which at least one PN junction is formed by a plurality of compound semiconductor layers, each having a different chemical composition, the method including: a process of forming a cell main body by forming an etching-stop layer for suppressing infiltration of an etching solution from the side of a substrate, a contact layer, an emitter layer made of a first conductivity type compound semiconductor, a base layer forming a PN junction with the emitter layer, and a buffer layer; a process of forming a rear surface electrode on the cell main body; a process of annealing the rear surface electrode; a process of forming a base material on the rear surface electrode; a process of attaching a reinforcing material on the base material; a process of separating the substrate from the cell main body; a process of forming a surface electrode on the exposed surface of the separated cell main body; a process of separating the reinforcing material; and a process of
- the method for manufacturing the thin film compound solar cell includes a process of, after the annealing of the surface electrode, separating the thin film compound solar cell into a plurality of solar cell elements, and a process of connecting a metallic ribbon to each of the electrodes.
- the rear surface electrode is formed in the early stage, and thereby the rear surface electrode can be annealed, so that it is possible to improve the adhesive property of the electrode and to reduce the contact resistance of the electrode. Further, a metallic ribbon is finally connected, and thereby it is possible to eliminate the unnecessary protection for the metallic ribbon.
- the cell main body includes an etching-stop layer and a contact layer respectively laminated on the side of the substrate. Also, the method for manufacturing the thin film compound solar cell includes a process of, after the separation of the substrate, removing the etching-stop layer from the cell main body, a process of etching the contact layer into a predetermined pattern, and a process of mesa-etching the cell main body, and forms the surface electrode on the mesa-etched contact layer.
- the method for manufacturing the thin film compound solar cell includes a process of, after the separation of the substrate, removing the etching-stop layer from the cell main body, a process of mesa-etching the cell main body, and a process of, after the surface electrode is formed on the contact layer, etching the contact layer.
- the surface electrode functions as an etching mask.
- the base material is made of a material having heat resistance capable of withstanding a temperature higher than the annealing temperature of the surface electrode and is made of, for example, a film-like polyimide.
- the polyimide film is formed by applying and annealing a resinous polyimide.
- the polyimide film is formed by applying and annealing a solution of polyamic acid which is a polyimide precursor. Further, the thickness of the polyimide film is set to 15 ⁇ m or less.
- the surface electrode can be sintered after the formation of the base material.
- a thin film compound solar cell which includes: a compound semiconductor layer with at least one PN junction formed therein; a surface electrode formed on one surface of the compound semiconductor layer; a polyimide film formed on the other surface of the compound semiconductor layer; and a rear surface electrode sandwiched between the compound semiconductor layer and the polyimide film.
- the compound semiconductor layer is made of an epitaxially grown single crystal thin film.
- the surface electrode and the rear surface electrode are annealed, it is possible to improve the adhesive property of each of the electrodes and to reduce the contact resistance of each of the electrodes. Further, the heat-resistant base material is used. Thus, after the reinforcing material is removed, the electrode can be annealed in the state where the base material is attached. As a result, the reinforcing material is not heat-treated, and hence the reinforcing material can be reused.
- a highly heat-resistant film such as polyimide, is used as the base material, and hence the film itself serves as the supporting body. Therefore, even when an external force is applied, the photovoltaic cell is not broken. Further, since the amount of warpage of the photovoltaic cell is changed according to the film thickness, it is possible to control the warpage of the cell during the film forming process.
- FIG. 1 is a cross-sectional view of a thin film compound solar cell according to the present invention when a cell main body made of a plurality of compound semiconductor layers is formed.
- FIG. 2 is a cross-sectional view of the thin film compound solar cell when a rear surface electrode is formed.
- FIG. 3 is a cross-sectional view of the thin film compound solar cell when a rear surface film is formed.
- FIG. 4 is a cross-sectional view of the thin film compound solar cell when a reinforcing material is attached.
- FIG. 5 is a cross-sectional view of the thin film compound solar cell when a substrate is removed.
- FIG. 6 is a cross-sectional view of the thin film compound solar cell when an etching-stop layer is removed.
- FIG. 7 is a cross-sectional view of the thin film compound solar cell when a first protective film is formed.
- FIG. 8 is a cross-sectional view of the thin film compound solar cell when the protective film is patterned.
- FIG. 9 is a cross-sectional view of the thin film compound solar cell when a contact layer is etched.
- FIG. 10 is a cross-sectional view of the thin film compound solar cell when the protective film is separated.
- FIG. 11 is a cross-sectional view of the thin film compound solar cell when a second protective film is formed.
- FIG. 12 is a cross-sectional view of the thin film compound solar cell when the protective film is patterned.
- FIG. 13 is a cross-sectional view of the thin film compound solar cell at the time of mesa-etching.
- FIG. 14 is a cross-sectional view of the thin film compound solar cell when the protective film is separated.
- FIG. 15 is a cross-sectional view of the thin film compound solar cell when a third protective film formed.
- FIG. 16 is a cross-sectional view of the thin film compound solar cell at the time of patterning for forming a surface electrode.
- FIG. 17 is a cross-sectional view of the thin film compound solar cell when the surface electrode is formed.
- FIG. 18 is a cross-sectional view of the thin film compound solar cell when the protective film is removed.
- FIG. 19 is a cross-sectional view of the thin film compound solar cell when the reinforcing material is separated.
- FIG. 20 is a cross-sectional view of the thin film compound semiconductor solar cell when the cell is divided into solar cell elements.
- FIG. 21 is a cross-sectional view of a thin film compound solar cell when mesa-etching is performed before the contact layer etching in another manufacturing method.
- FIG. 22 is a cross-sectional view of the thin film compound solar cell when the surface electrode is formed in another manufacturing method.
- FIG. 23 is a cross-sectional view of the thin film compound solar cell when the contact layer is etched in another manufacturing method.
- FIG. 24 is a cross-sectional view of the thin film compound solar cell when a cell main body is formed in a conventional manufacturing method.
- FIG. 25 is a cross-sectional view of the thin film compound solar cell when a contact layer is etched.
- FIG. 26 is a cross-sectional view of the thin film compound solar cell when a surface electrode is formed.
- FIG. 27 is a cross-sectional view of the thin film compound solar cell when the cell is separated into solar cell elements.
- FIG. 28 is a cross-sectional view of the thin film compound solar cell when a surface film is formed.
- FIG. 29 is a cross-sectional view of the thin film compound solar cell when a reinforcing material is attached.
- FIG. 30 is a cross-sectional view of the thin film compound solar cell when a substrate is removed.
- FIG. 31 is a cross-sectional view of the thin film compound solar cell when a rear surface electrode is formed.
- FIG. 32 is a cross-sectional view of the thin film compound solar cell when the reinforcing material is separated.
- a thin film compound solar cell has a structure including: a cell main body in which at least one PN junction is formed by laminating a plurality of compound semiconductor layers, each having a different chemical composition; a surface electrode which is formed on the light receiving surface of the cell main body; a rear surface electrode which is formed on the opposite surface of the cell main body; and a base material for the thin film solar cell.
- the base material is formed on the opposite surface of the cell main body, and the rear surface electrode is sandwiched between the cell main body and the base material.
- a compound semiconductor layer made of single crystal thin films is formed by laminating, on a substrate 1 , an etching-stop layer 2 for suppressing infiltration of an etching solution from the side of the substrate, a contact layer 3 , an emitter layer 4 made of a first compound semiconductor, a base layer 5 forming a PN junction with the emitter layer 4 , and a buffer layer 6 in this order.
- the substrate 1 has, for example, a wafer-like form, and a cell main body is formed by laminating, on the substrate 1 , compound semiconductor layers, such as the etching-stop layer 2 , the contact layer 3 , the emitter layer 4 , the base layer 5 , and the buffer layer 6 , by a known process, for example, the epitaxial growth method described in Patent Document 1.
- compound semiconductor layers such as the etching-stop layer 2 , the contact layer 3 , the emitter layer 4 , the base layer 5 , and the buffer layer 6 .
- the substrate 1 it is possible to use a wafer made of a material, such as Ge, GaP, and GaAs.
- the compound semiconductor layers for example, the etching-stop layer 2 such as an InGaP layer, the contact layer 3 such as an AlInP layer, the emitter layer 4 such as an N-type InGaP layer, the base layer 5 such as a P-type InGaP layer, and the buffer layer 6 such as an AlInP layer are used.
- the cell main body is assumed to have the 5 layer structure, but the layer structure of the cell main body is not limited to this.
- the cell main body may have, for example, a four layer structure, a six layer structure, or the like.
- the cell main body may include compound semiconductor layers, such as a BSF (back surface field) layer, a window layer, a tunnel junction layer of a multi-junction type solar cell, and the other emitter layer and the other base layer of the multi-junction type solar cell.
- BSF back surface field
- the cell main body formed on the substrate 1 is made of a plurality of compound semiconductor layers, each having a different chemical composition, and that at least one PN junction is formed by the plurality of compound semiconductor layers. Further, it is only necessary that the plurality of compound semiconductor layers include at least a layer which is easily etched by a second etching solution for etching the contact layer and which is hardly etched by a third etching solution for mesa-etching, and a layer which is hardly etched by the second etching solution and which is easily etched by the third etching solution.
- the former layer is the contact layer 3
- the latter layers are the emitter layer 4 and the base layer 5 .
- a rear surface electrode 7 is formed on the surface of the buffer layer 6 which is the outermost surface of the compound semiconductor layers (the etching-stop layer 2 , the contact layer 3 , the emitter layer 4 , the base layer 5 , and the buffer layer 6 ) laminated onto each other.
- the rear surface electrode 7 is formed all over the compound semiconductor layer.
- the rear surface electrode 7 is formed by a method in which a metal paste made of Al, Ag, or the like, is applied to the outermost surface of the cell main body by screen printing. After the formation of the rear surface electrode 7 , the cell main body is subjected to heat treatment, so that the rear surface electrode 7 is annealed. Therefore, the contact resistance between the surface of the compound semiconductor layer and the rear surface electrode 7 can be reduced, and the adhesive force between the surface of the compound semiconductor layer and the rear surface electrode 7 can be increased.
- a highly heat-resistant rear surface film S is formed on the rear surface electrode 7 .
- the rear surface film 8 is made of a material having heat resistance capable of withstanding a temperature of 300° C. or more, and, for example, polyimide is used as the material of the rear surface film 8 .
- the method for forming the rear surface film 8 includes a method in which a varnish-like resin is applied on the rear surface electrode 7 at a normal temperature by a spin-coating method, or the like, and then annealed.
- the film thickness of polyimide is 20 ⁇ m or more, air bubbles are mixed into the polyimide film, so as to prevent a flat film from being annealed, and because the amount of warpage of the polyimide film is also large, so as to damage the cell main body.
- the film thickness of polyimide is reduced, the mixing of air bubbles is prevented in the thickness range of 20 ⁇ m or less, and the warpage of the polyimide film is also reduced.
- the film thickness of polyimide is about 7 ⁇ m, the amount of warpage of the polyimide film is minimized.
- the film thickness of polyimide is less than about 7 ⁇ m, the direction of warpage is reversed, and the amount of warpage is again increased. Therefore, as a result of consideration of the warpage amount of polyimide, and of the elasticity of polyimide as the base material of the cell main body, the film thickness of polyimide in the range of 5 to 15 ⁇ m is suitable for the production of the cell main body, and in particular the film thickness of about 7 ⁇ m is optimum.
- the method in which the film is formed by annealing the varnish-like polyimide, is exemplified.
- a thermal fusion adhesive film is used and press-fitted to the rear surface electrode 7 while being heated.
- the rear surface film 8 is formed as the base material of the thin film solar cell so as to serve as the supporting surface film is set to 15 ⁇ m or less, the base material with a less warpage amount can be formed, so that the warpage of the cell main body is controlled to reduce the warpage of the cell main body.
- a reinforcing material 9 for reinforcing the compound semiconductor layer is bonded onto the rear surface film 8 .
- the reinforcing material 9 it is preferred to use a PET film, and the like, with an adhesive material whose adhesive force is lowered by irradiation of UV light. Thereby, the reinforcing material 9 can be directly attached to the rear surface film 8 .
- the substrate 1 is etched and removed by using a first etching solution.
- a proper solution is selectively used according to the material of the substrate.
- the etching-stop layer 2 is a layer which is hardly etched by the first etching solution.
- the etching-stop layer 2 is removed by being etched by the second etching solution.
- the contact layer 3 is exposed at the outermost surface.
- a first protective film 10 is applied and formed on the contact layer 3 in order to protect the outermost surface of the cell main body from the chemical treatment (contact layer etching).
- the protective film 10 has resistance against the second etching solution used to etch the compound semiconductor layer in the subsequent process.
- a photoresist is used as the protective film 10 , the processing is easily and surely performed.
- the patterning of the protective film 10 for forming a surface electrode is performed by using a glass mask, so that an opening section is formed in the protective film 10 .
- the protective film 10 serves as an etching mask when the contact layer is etched in the subsequent process.
- the contact layer is etched.
- the cell main body is immersed in the second etching solution capable of etching the compound semiconductor layer, so that the contact layer 3 is etched by using the patterned protective film 10 as an etching mask.
- An alkali solution is used as the second etching solution.
- a part of the emitter layer 4 is exposed at the outermost surface.
- the protective film 10 used as the etching mask for etching the contact layer is separated by a lift-off method.
- a second protective film 11 is applied and formed in order to protect the outermost surface of the cell main body from mesa-etching.
- a photoresist is used as the second protective film 11 .
- an opening section for defining the region of a solar cell element is formed in the protective film 11 by patterning the protective film 11 by using a glass mask.
- the protective film 11 serves as an etching mask at the time of mesa-etching in the subsequent process.
- the cell main body is immersed in the third etching solution capable of etching the compound semiconductor layer, so that the cell main body is mesa-etched by using the patterned protective film 11 as an etching mask.
- the emitter layer 4 and the base layer 5 are etched along the patterned protective film 11 .
- An alkali solution and an acid solution are used as the third etching solution.
- the region of the solar cell element can be defined by the mesa-etching.
- the protective film 11 used as the etching mask is separated by the lift-off method.
- a third protective film 12 made of a photoresist is applied and formed on the whole outer surface of the etched cell main body in order to perform the patterning of the surface electrode.
- the protective film 12 is patterned by using a glass mask, and thereby an opening section is formed in the protective film 12 so that the patterning of the surface electrode can be performed. At this time, the patterning of the protective film 12 is performed so that the opening section is formed on the contact layer 3 patterned by the preceding process.
- the cell main body, to which the reinforcing material 9 is attached is set in an electrode forming apparatus.
- a surface electrode 13 is formed on the protective film 12 and in the opening section of the protective film 12 .
- the surface electrode 13 is formed by applying an electrode material, such as Al or Ag, to the outermost surface of the cell main body by screen printing, or by vapor-depositing the electrode material on the outermost surface.
- the cell main body, on which the electrode material laminated is immersed in an organic solvent, such as acetone.
- the photoresist which is the protective film 12 , is dissolved in the organic solvent, so that the electrode material attached on the photoresist is removed together with the photoresist.
- the electrode material is selectively attached only in the opening section, and thereby the surface electrode 13 is formed on the contact layer 3 , so that the thin film compound semiconductor solar cell is formed.
- the thin film compound semiconductor solar cell is separated from the reinforcing material 9 .
- the separation method when the UV separation type material is used as the adhesive material, a method is used, in which the reinforcing material 9 is separated from the cell main body by irradiating UV light by using a UV irradiation apparatus.
- the surface electrode 13 is annealed. By performing the heat treatment, it is possible to reduce the contact resistance between the contact layer 3 and the surface electrode 13 , and to improve the adhesive property between the contact layer 3 and the surface electrode 13 .
- the thin film compound solar cell formed in the wafer is separated into a plurality of solar cell elements.
- the separation method a method is used, in which the thin film compound solar cell is fixed to a stage by vacuum suction, or the like, and in which the opening section formed by the mesa-etching is cut by a scriber so that the plurality of solar cell elements are formed.
- a metallic ribbon made of Ag, or the like, for establishing electrical connection between the respective elements is connected by welding, or the like, to an electrode pad on the electrode of each of the solar cell elements.
- the reinforcing material 9 is directly bonded to the rear surface film 8 as the base material without using an adhesive, such as wax.
- an adhesive such as wax.
- the rear surface film 8 has heat resistance capable of withstanding a temperature higher than the annealing temperature of the surface electrode 13 , and hence it is possible to anneal the surface electrode 13 after the rear surface film S is formed on the rear surface electrode 7 .
- the adhesive property of the electrodes with the cell main body is improved, so as to prevent each of the electrodes from being separated. Further, the contact resistance between the electrodes and the compound semiconductor layer can be reduced, so that the conversion efficiency is increased.
- the structure, in which the surface electrode 13 is not covered with a surface film, is adopted, and hence the surface electrode 13 is exposed.
- the metallic ribbon can be connected, and hence it is not necessary that, as in the conventional case, the metallic ribbon is protected when the substrate is removed. As a result, the number of processes can be reduced.
- a highly heat-resistant film such as polyimide, is used as the base material, and thereby the film itself serves as a supporting body. Therefore, even when an external force is applied, the photovoltaic cell is prevented from being broken. Further, since the amount of warpage of the photovoltaic cell is changed according to the thickness of the film, the warpage of the cell can be reduced in such a manner that, when the film is formed, the thickness of the film is adjusted over the whole cell according to the thickness of the cell.
- the present invention is not limited to the above described embodiment, but numerous modifications and changes can be obviously made therein without departing from the spirit and scope of the present invention.
- the substrate 1 is separated from the cell main body, and the etching-stop layer 2 is removed. Then, the cell main body is mesa-etched as shown in FIG. 21 .
- a protective film made of a photoresist is formed on the contact layer 3 , and the patterning for forming the surface electrode is performed.
- An electrode material is laminated on the protective film and on the contact layer 3 in the opening section. When the protective film is removed, the surface electrode 13 is formed as shown in FIG. 22 .
- the contact layer 3 is etched by the contact layer etching.
- the surface electrode 13 is used as an etching mask.
- the reinforcing material 9 is separated from the cell main body, and the surface electrode 13 is annealed.
- the thin film compound solar cell is separated into a plurality of solar cell elements, and the metallic ribbon is finally connected to each of the solar cell elements.
- the surface electrode 13 serves as a protective film in the contact layer etching.
- the process of forming the protective film used to perform the contact layer etching can be eliminated, and hence the number of processes can be reduced.
- the rear surface film is formed by applying and sintering a solution of polyamic acid which is a polyimide precursor. That is, a solution of varnish-like polyamic acid is applied on the rear surface electrode, and is annealed stepwise so that a polyimide film is formed.
- the polyamic acid solution is applied on the rear surface electrode by a spin-coating method, or the like. Thereafter, when annealing is first performed at 120° C. for one hour, the solvent of polyamic acid is evaporated, and the solution is temporarily cured. Then, the annealing temperature is increased stepwise. Finally, the annealing temperature is increased to the temperature at which the polyamic acid is polymerized and changed to a polyimide film. By this main curing, the polyimide film is formed.
- the reason for performing the annealing stepwise in this way is that, when the annealing is performed from the beginning at a temperature at which the polyamic acid starts to be polymerized, the surface layer of the polyamic acid solution is cured prior to the curing in the inside of the polyamic acid solution, with the result that an air bubble included in the solution at the time of annealing is left in the inside of the polyamic acid solution, and that the air bubble left in the inside of the polyamic acid solution is expanded to form a portion at which the rear surface electrode is not in close contact with the polyimide film.
- the contraction degree of the surface layer portion of the formed polyimide film becomes larger than the contraction degree in the inside of the polyimide film, so that the amount of warpage of the polyimide film is increased and thereby the photovoltaic cell is greatly warped.
- the annealing temperature is increased stepwise as described above, the air bubble is prevented from being generated in the inside of the polyamic acid solution and the difference in the contraction degree between the surface layer portion and the inside of the polyimide film can also be prevented from occurring.
Abstract
To manufacture a thin film compound solar cell which can improve the adhesive property of electrodes even when being provided with a base material, and which prevents the base material from being separated. A cell main body configured by laminating a plurality of compound semiconductor layers is formed on a substrate. A rear surface electrode 7 is formed on the cell main body, and a rear surface film 8 as the base material is formed on the rear surface electrode 7. A reinforcing material 9 is attached on the rear surface film 8. The substrate is separated from the cell main body, and the cell main body is mesa-etched. A surface electrode 13 is formed on a contact layer 3 after the etching. The reinforcing material 9 is separated, and the surface electrode 13 is annealed. The formed thin film compound solar cell is separated into a plurality of solar cell elements.
Description
- The present invention relates to a method for manufacturing a thin film compound solar cell having a cell main body in which at least one PN junction is formed by a plurality of compound semiconductor layers, each having a different chemical composition.
- A conventional thin film compound solar cell is configured such that a surface electrode is provided on a light receiving surface of a cell main body formed by laminating a plurality of compound semiconductor layers, and such that a rear surface electrode is provided on the surface opposite to the light receiving surface of the cell main body.
- The thin film compound solar cell is manufactured as follows. In process A1 shown in
FIG. 24 , an etching-stop layer 102, abase layer 103, anemitter layer 104, and acontact layer 105 respectively formed by compound semiconductor layers are laminated in this order on asubstrate 101, so that a cell main body is formed. - In process A2 shown in
FIG. 25 , a protective film, such as a photoresist, is applied on the surface of thecontact layer 105, and the region of the protective film, which region is patterned by exposure, is etched. Thecontact layer 105 is patterned by contact layer etching. The applied resist is removed after the completion of the patterning. Next, a photoresist is again applied for formation of a surface electrode, and a protective film is formed. - In process A3 shown in
FIG. 26 , a protective film opening section is formed by patterning the photoresist by exposure so that the protective film opening section is included in the region of thecontact layer 105 formed by the preceding process. After a surface electrode is laminated, the photoresist is removed, so that asurface electrode 106 is selectively formed only in the protective film opening section. By this surface electrode forming process, the region of the surface electrode can be patterned so as to be included in the region of the contact layer formed by the preceding process. - After the completion of the patterning of the
surface electrode 106, thesurface electrode 106 is annealed at a temperature of about 350° C. in order to reduce the component of contact resistance between thesurface electrode 106 and thecontact layer 105 and to increase the adhesive force between thesurface electrode 106 and thecontact layer 105. - In process A4 shown in
FIG. 27 , the protective film is patterned by exposure so as to define a cell formation region corresponding to a predetermined shape (chip shape) of a solar cell element. A protective film opening section is formed, so that the opening section is mesa-etched. Then, the solar cell element having the predetermined shape (chip shape) is separated by mechanical means, such as dicing. - In process A5 shown in
FIG. 28 , a transparent resin, such as silicone resin, is applied to the side of the light receiving surface of the solar cell element, so that atransparent surface film 107 is bonded onto the transparent resin. Thereby, the thin film compound solar cell and thesurface film 107 are bonded to each other via the resin, so that thesurface film 107 serves as a base material of the thin film compound solar cell. - In process AG shown in
FIG. 29 , a reinforcingmaterial 108, such as glass or sapphire, is bonded via wax on the side of the light receiving surface of the solar cell element, to which side thesurface film 107 is bonded. - In process A7 shown in
FIG. 30 , the solar cell element, to which the reinforcingmaterial 108 is bonded, is immersed in an etchant. Since the etching is stopped at the etching-stop layer 102, only thesubstrate 101 can be removed so that only the cell main body is left. Thereby, thesubstrate 101 is separated from the compound semiconductor layers, so that the solar cell element exhibits its flexibility. - In process A8 shown in
FIG. 31 , an electrode material is vapor-deposited on the exposed rear surface of the compound semiconductor layer, so that arear surface electrode 109 is formed. - In process A9 shown in
FIG. 32 , the wax bonding the reinforcingmaterial 108 to the solar cell element is finally is dissolved by an organic solvent, such as acetone, so that the reinforcingmaterial 108 is removed from the solar cell element. - The thin film compound solar cell manufactured as described above has the structure in which the surface film as the base material is bonded to the light receiving surface of the cell main body with a PN junction formed therein.
- Meanwhile, the surface film is bonded on the side of the light receiving surface, and hence high transparency is required for the surface film so as to prevent the conversion efficiency of the solar cell element from being impaired. The high transparency film generally has low temperature resistance. In the conventional method for manufacturing the thin film compound solar cell, the process is performed such that, after the surface film is bonded to the solar cell element, the substrate is removed and the rear surface electrode is formed. After the formation of the rear surface electrode, it is necessary to anneal the rear surface electrode in order to reduce the component of contact resistance between the rear surface electrode and the compound semiconductor layer, and in order to increase the adhesive force between the rear surface electrode and the compound semiconductor layer. The annealing temperature is higher than the heat-resistant temperature of the surface film, and hence the rear surface electrode cannot be annealed in the state where the surface film is bonded to the solar cell element. Therefore, there is a problem that the rear surface electrode is separated from the compound semiconductor layer.
- Further, when the wax used to bond the solar cell element to the reinforcing material is dissolved by the organic solvent, the resin used to bond the compound semiconductor layer to the surface film is also exposed to the organic solvent at the same time. Thus, there is a problem that, when the resin is exposed to the organic solvent and water, the exposed resin penetrates into the interface between the surface film and the resin, or into the interface between the compound semiconductor layer and the resin, so as to make the surface film liable to be separated from the compound semiconductor layer.
- Further, the process for removing the substrate by the etchant is performed after a metallic ribbon for establishing electrical connection is welded to the solar cell element. As the etchant for etching the substrate, it is necessary to use hydrofluoric acid, and the like, depending on the substrate material. However, hydrofluoric acid reacts with the metallic ribbon to corrode the metallic ribbon. At the time of etching the substrate, the exposed metallic ribbon is required to be protected by being covered with an acid resistant material. This results in a problem that the number of processes is increased.
- Here, a method for manufacturing the compound solar cell described in
Patent Document 1 includes: forming the rear surface electrode on the cell main body; attaching a support plate on the rear surface electrode; separating the substrate from the cell main body to expose the surface of the cell main body; forming the surface electrode on the exposed surface of the cell main body; and then removing the support plate. - In the compound solar cell described in
Patent Document 1, the rear surface electrode is formed first. For this reason, after the rear surface electrode is annealed, the surface film can be bonded. However, in the above-described compound solar cell described in Patent Document, the surface film as the base material is not provided, and hence the problem of separation of the surface film does not occur. -
- Patent Document 1: Japanese Patent Laid-Open No. 2004
- The structure of the solar-battery cell described in
Patent Document 1 has a problem that, since the structure is configured only by the semiconductor epitaxial layer and the rear surface electrode, the epitaxial layer is easily broken when an external force due to bending, or the like, is applied to the structure. Further, in the structure configured only by the semiconductor epitaxial layer and the rear surface electrode, the warpage of the solar-battery cell cannot be controlled. - Thus, in view of the above, an object of the present invention is to provide a method for manufacturing a thin film compound solar cell which can improve the adhesive property of the electrode even when provided with the base material and which can withstand the external force without the separation of the base material.
- The present invention provides a method for manufacturing a thin film compound solar cell having a cell main body in which at least one PN junction is formed by a plurality of compound semiconductor layers, each having a different chemical composition, the method including: a process of forming a cell main body by forming an etching-stop layer for suppressing infiltration of an etching solution from the side of a substrate, a contact layer, an emitter layer made of a first conductivity type compound semiconductor, a base layer forming a PN junction with the emitter layer, and a buffer layer; a process of forming a rear surface electrode on the cell main body; a process of annealing the rear surface electrode; a process of forming a base material on the rear surface electrode; a process of attaching a reinforcing material on the base material; a process of separating the substrate from the cell main body; a process of forming a surface electrode on the exposed surface of the separated cell main body; a process of separating the reinforcing material; and a process of sintering the surface electrode. Further, the method for manufacturing the thin film compound solar cell includes a process of, after the annealing of the surface electrode, separating the thin film compound solar cell into a plurality of solar cell elements, and a process of connecting a metallic ribbon to each of the electrodes.
- The rear surface electrode is formed in the early stage, and thereby the rear surface electrode can be annealed, so that it is possible to improve the adhesive property of the electrode and to reduce the contact resistance of the electrode. Further, a metallic ribbon is finally connected, and thereby it is possible to eliminate the unnecessary protection for the metallic ribbon.
- In the method for manufacturing the thin film compound solar cell, the cell main body includes an etching-stop layer and a contact layer respectively laminated on the side of the substrate. Also, the method for manufacturing the thin film compound solar cell includes a process of, after the separation of the substrate, removing the etching-stop layer from the cell main body, a process of etching the contact layer into a predetermined pattern, and a process of mesa-etching the cell main body, and forms the surface electrode on the mesa-etched contact layer.
- Alternatively, the method for manufacturing the thin film compound solar cell includes a process of, after the separation of the substrate, removing the etching-stop layer from the cell main body, a process of mesa-etching the cell main body, and a process of, after the surface electrode is formed on the contact layer, etching the contact layer. In this case, the surface electrode functions as an etching mask.
- The base material is made of a material having heat resistance capable of withstanding a temperature higher than the annealing temperature of the surface electrode and is made of, for example, a film-like polyimide. The polyimide film is formed by applying and annealing a resinous polyimide. Alternatively, the polyimide film is formed by applying and annealing a solution of polyamic acid which is a polyimide precursor. Further, the thickness of the polyimide film is set to 15 μm or less.
- Here, it is technically impossible to bond the polyimide film onto the rear surface electrode by using an adhesive, because of the problem of the heat-resistance of the adhesive itself. Thus, when the base material is formed by the above-described method, the surface electrode can be sintered after the formation of the base material.
- With the above-described manufacturing method, a thin film compound solar cell is manufactured, which includes: a compound semiconductor layer with at least one PN junction formed therein; a surface electrode formed on one surface of the compound semiconductor layer; a polyimide film formed on the other surface of the compound semiconductor layer; and a rear surface electrode sandwiched between the compound semiconductor layer and the polyimide film. Note that the compound semiconductor layer is made of an epitaxially grown single crystal thin film.
- According to the present invention, since the surface electrode and the rear surface electrode are annealed, it is possible to improve the adhesive property of each of the electrodes and to reduce the contact resistance of each of the electrodes. Further, the heat-resistant base material is used. Thus, after the reinforcing material is removed, the electrode can be annealed in the state where the base material is attached. As a result, the reinforcing material is not heat-treated, and hence the reinforcing material can be reused.
- Further, a highly heat-resistant film, such as polyimide, is used as the base material, and hence the film itself serves as the supporting body. Therefore, even when an external force is applied, the photovoltaic cell is not broken. Further, since the amount of warpage of the photovoltaic cell is changed according to the film thickness, it is possible to control the warpage of the cell during the film forming process.
-
FIG. 1 is a cross-sectional view of a thin film compound solar cell according to the present invention when a cell main body made of a plurality of compound semiconductor layers is formed. -
FIG. 2 is a cross-sectional view of the thin film compound solar cell when a rear surface electrode is formed. -
FIG. 3 is a cross-sectional view of the thin film compound solar cell when a rear surface film is formed. -
FIG. 4 is a cross-sectional view of the thin film compound solar cell when a reinforcing material is attached. -
FIG. 5 is a cross-sectional view of the thin film compound solar cell when a substrate is removed. -
FIG. 6 is a cross-sectional view of the thin film compound solar cell when an etching-stop layer is removed. -
FIG. 7 is a cross-sectional view of the thin film compound solar cell when a first protective film is formed. -
FIG. 8 is a cross-sectional view of the thin film compound solar cell when the protective film is patterned. -
FIG. 9 is a cross-sectional view of the thin film compound solar cell when a contact layer is etched. -
FIG. 10 is a cross-sectional view of the thin film compound solar cell when the protective film is separated. -
FIG. 11 is a cross-sectional view of the thin film compound solar cell when a second protective film is formed. -
FIG. 12 is a cross-sectional view of the thin film compound solar cell when the protective film is patterned. -
FIG. 13 is a cross-sectional view of the thin film compound solar cell at the time of mesa-etching. -
FIG. 14 is a cross-sectional view of the thin film compound solar cell when the protective film is separated. -
FIG. 15 is a cross-sectional view of the thin film compound solar cell when a third protective film formed. -
FIG. 16 is a cross-sectional view of the thin film compound solar cell at the time of patterning for forming a surface electrode. -
FIG. 17 is a cross-sectional view of the thin film compound solar cell when the surface electrode is formed. -
FIG. 18 is a cross-sectional view of the thin film compound solar cell when the protective film is removed. -
FIG. 19 is a cross-sectional view of the thin film compound solar cell when the reinforcing material is separated. -
FIG. 20 is a cross-sectional view of the thin film compound semiconductor solar cell when the cell is divided into solar cell elements. -
FIG. 21 is a cross-sectional view of a thin film compound solar cell when mesa-etching is performed before the contact layer etching in another manufacturing method. -
FIG. 22 is a cross-sectional view of the thin film compound solar cell when the surface electrode is formed in another manufacturing method. -
FIG. 23 is a cross-sectional view of the thin film compound solar cell when the contact layer is etched in another manufacturing method. -
FIG. 24 is a cross-sectional view of the thin film compound solar cell when a cell main body is formed in a conventional manufacturing method. -
FIG. 25 is a cross-sectional view of the thin film compound solar cell when a contact layer is etched. -
FIG. 26 is a cross-sectional view of the thin film compound solar cell when a surface electrode is formed. -
FIG. 27 is a cross-sectional view of the thin film compound solar cell when the cell is separated into solar cell elements. -
FIG. 28 is a cross-sectional view of the thin film compound solar cell when a surface film is formed. -
FIG. 29 is a cross-sectional view of the thin film compound solar cell when a reinforcing material is attached. -
FIG. 30 is a cross-sectional view of the thin film compound solar cell when a substrate is removed. -
FIG. 31 is a cross-sectional view of the thin film compound solar cell when a rear surface electrode is formed. -
FIG. 32 is a cross-sectional view of the thin film compound solar cell when the reinforcing material is separated. -
-
- 1 substrate
- 2 etching-stop layer
- 3 contact layer
- 4 emitter layer
- 5 base layer
- 6 buffer layer
- 7 rear surface electrode
- 8 rear surface film
- 9 reinforcing material
- 10 first protective film
- 11 second protective film
- 12 third protective film
- 13 surface electrode
- A thin film compound solar cell according to the present embodiment has a structure including: a cell main body in which at least one PN junction is formed by laminating a plurality of compound semiconductor layers, each having a different chemical composition; a surface electrode which is formed on the light receiving surface of the cell main body; a rear surface electrode which is formed on the opposite surface of the cell main body; and a base material for the thin film solar cell. The base material is formed on the opposite surface of the cell main body, and the rear surface electrode is sandwiched between the cell main body and the base material.
- A method for manufacturing the solar cell having this structure will be described. In
process 1 shown inFIG. 1 , a compound semiconductor layer made of single crystal thin films is formed by laminating, on asubstrate 1, an etching-stop layer 2 for suppressing infiltration of an etching solution from the side of the substrate, acontact layer 3, anemitter layer 4 made of a first compound semiconductor, abase layer 5 forming a PN junction with theemitter layer 4, and abuffer layer 6 in this order. Thesubstrate 1 has, for example, a wafer-like form, and a cell main body is formed by laminating, on thesubstrate 1, compound semiconductor layers, such as the etching-stop layer 2, thecontact layer 3, theemitter layer 4, thebase layer 5, and thebuffer layer 6, by a known process, for example, the epitaxial growth method described inPatent Document 1. - As the
substrate 1, it is possible to use a wafer made of a material, such as Ge, GaP, and GaAs. As the compound semiconductor layers, for example, the etching-stop layer 2 such as an InGaP layer, thecontact layer 3 such as an AlInP layer, theemitter layer 4 such as an N-type InGaP layer, thebase layer 5 such as a P-type InGaP layer, and thebuffer layer 6 such as an AlInP layer are used. - Note that the cell main body is assumed to have the 5 layer structure, but the layer structure of the cell main body is not limited to this. The cell main body may have, for example, a four layer structure, a six layer structure, or the like. Further, other than the etching-
stop layer 2, thecontact layer 3, theemitter layer 4, thebase layer 5, and thebuffer layer 6, the cell main body may include compound semiconductor layers, such as a BSF (back surface field) layer, a window layer, a tunnel junction layer of a multi-junction type solar cell, and the other emitter layer and the other base layer of the multi-junction type solar cell. - That is, it is only necessary that the cell main body formed on the
substrate 1 is made of a plurality of compound semiconductor layers, each having a different chemical composition, and that at least one PN junction is formed by the plurality of compound semiconductor layers. Further, it is only necessary that the plurality of compound semiconductor layers include at least a layer which is easily etched by a second etching solution for etching the contact layer and which is hardly etched by a third etching solution for mesa-etching, and a layer which is hardly etched by the second etching solution and which is easily etched by the third etching solution. The former layer is thecontact layer 3, and the latter layers are theemitter layer 4 and thebase layer 5. - In
process 2 shown inFIG. 2 , arear surface electrode 7 is formed on the surface of thebuffer layer 6 which is the outermost surface of the compound semiconductor layers (the etching-stop layer 2, thecontact layer 3, theemitter layer 4, thebase layer 5, and the buffer layer 6) laminated onto each other. Therear surface electrode 7 is formed all over the compound semiconductor layer. Therear surface electrode 7 is formed by a method in which a metal paste made of Al, Ag, or the like, is applied to the outermost surface of the cell main body by screen printing. After the formation of therear surface electrode 7, the cell main body is subjected to heat treatment, so that therear surface electrode 7 is annealed. Therefore, the contact resistance between the surface of the compound semiconductor layer and therear surface electrode 7 can be reduced, and the adhesive force between the surface of the compound semiconductor layer and therear surface electrode 7 can be increased. - In
process 3 shown inFIG. 3 , after the formation of therear surface electrode 7, a highly heat-resistant rear surface film S is formed on therear surface electrode 7. Therear surface film 8 is made of a material having heat resistance capable of withstanding a temperature of 300° C. or more, and, for example, polyimide is used as the material of therear surface film 8. The method for forming therear surface film 8 includes a method in which a varnish-like resin is applied on therear surface electrode 7 at a normal temperature by a spin-coating method, or the like, and then annealed. - When the
rear surface film 8 is formed by applying and annealing a varnish of polyimide, it is necessary to control the film thickness of polyimide. This is because, when the film thickness of polyimide is 20 μm or more, air bubbles are mixed into the polyimide film, so as to prevent a flat film from being annealed, and because the amount of warpage of the polyimide film is also large, so as to damage the cell main body. When the film thickness of polyimide is reduced, the mixing of air bubbles is prevented in the thickness range of 20 μm or less, and the warpage of the polyimide film is also reduced. When the film thickness of polyimide is about 7 μm, the amount of warpage of the polyimide film is minimized. When the film thickness of polyimide is less than about 7 μm, the direction of warpage is reversed, and the amount of warpage is again increased. Therefore, as a result of consideration of the warpage amount of polyimide, and of the elasticity of polyimide as the base material of the cell main body, the film thickness of polyimide in the range of 5 to 15 μm is suitable for the production of the cell main body, and in particular the film thickness of about 7 μm is optimum. Note that, in the above, the method, in which the film is formed by annealing the varnish-like polyimide, is exemplified. However, besides this method, there is a method in which a thermal fusion adhesive film is used and press-fitted to therear surface electrode 7 while being heated. Thereby, therear surface film 8 is formed as the base material of the thin film solar cell so as to serve as the supporting surface film is set to 15 μm or less, the base material with a less warpage amount can be formed, so that the warpage of the cell main body is controlled to reduce the warpage of the cell main body. - In
process 4 shown inFIG. 4 , after the formation of therear surface film 8, a reinforcingmaterial 9 for reinforcing the compound semiconductor layer is bonded onto therear surface film 8. As the reinforcingmaterial 9, it is preferred to use a PET film, and the like, with an adhesive material whose adhesive force is lowered by irradiation of UV light. Thereby, the reinforcingmaterial 9 can be directly attached to therear surface film 8. - In
process 5 shown inFIG. 5 , after the bonding of the reinforcingmaterial 9, thesubstrate 1 is etched and removed by using a first etching solution. As the first etching solution, a proper solution is selectively used according to the material of the substrate. In the case where the substrate is made of Ge, it is preferred to use a solution having a composition of hydrofluoric acid:aqueous hydrogen peroxide:water=1:1:4. The etching-stop layer 2 is a layer which is hardly etched by the first etching solution. Thus, when the substrate is etched so that the etching-stop layer 2 is exposed, the progress of etching is stopped. Thereby, only thesubstrate 1 can be separated so that only the compound semiconductor layer is left. - In
process 6 shown inFIG. 6 , after the etching of the substrate, the etching-stop layer 2 is removed by being etched by the second etching solution. Thecontact layer 3 is exposed at the outermost surface. - In
process 7 shown inFIG. 7 , a firstprotective film 10 is applied and formed on thecontact layer 3 in order to protect the outermost surface of the cell main body from the chemical treatment (contact layer etching). Theprotective film 10 has resistance against the second etching solution used to etch the compound semiconductor layer in the subsequent process. When a photoresist is used as theprotective film 10, the processing is easily and surely performed. - In
process 8 shown inFIG. 8 , after the formation of theprotective film 10, the patterning of theprotective film 10 for forming a surface electrode is performed by using a glass mask, so that an opening section is formed in theprotective film 10. Theprotective film 10 serves as an etching mask when the contact layer is etched in the subsequent process. - In
process 9 shown inFIG. 9 , after theprotective film 10 is patterned, the contact layer is etched. The cell main body is immersed in the second etching solution capable of etching the compound semiconductor layer, so that thecontact layer 3 is etched by using the patternedprotective film 10 as an etching mask. An alkali solution is used as the second etching solution. A part of theemitter layer 4 is exposed at the outermost surface. - In
process 10 shown inFIG. 10 , after the etching of thecontact layer 3, theprotective film 10 used as the etching mask for etching the contact layer is separated by a lift-off method. - In
process 11 shown inFIG. 11 , a secondprotective film 11 is applied and formed in order to protect the outermost surface of the cell main body from mesa-etching. A photoresist is used as the secondprotective film 11. - In
process 12 shown inFIG. 12 , after the formation of theprotective film 11, an opening section for defining the region of a solar cell element is formed in theprotective film 11 by patterning theprotective film 11 by using a glass mask. Theprotective film 11 serves as an etching mask at the time of mesa-etching in the subsequent process. - In
process 13 shown inFIG. 13 , after the patterning of theprotective film 11, the cell main body is immersed in the third etching solution capable of etching the compound semiconductor layer, so that the cell main body is mesa-etched by using the patternedprotective film 11 as an etching mask. Theemitter layer 4 and thebase layer 5 are etched along the patternedprotective film 11. An alkali solution and an acid solution are used as the third etching solution. The region of the solar cell element can be defined by the mesa-etching. - In
process 14 shown inFIG. 14 , after the mesa-etching, theprotective film 11 used as the etching mask is separated by the lift-off method. - In
process 15 shown inFIG. 15 , a thirdprotective film 12 made of a photoresist is applied and formed on the whole outer surface of the etched cell main body in order to perform the patterning of the surface electrode. - In
process 16 shown inFIG. 16 , after the formation of theprotective film 12, theprotective film 12 is patterned by using a glass mask, and thereby an opening section is formed in theprotective film 12 so that the patterning of the surface electrode can be performed. At this time, the patterning of theprotective film 12 is performed so that the opening section is formed on thecontact layer 3 patterned by the preceding process. - In
process 17 shown inFIG. 17 , after the patterning of theprotective film 12, the cell main body, to which the reinforcingmaterial 9 is attached, is set in an electrode forming apparatus. Asurface electrode 13 is formed on theprotective film 12 and in the opening section of theprotective film 12. Thesurface electrode 13 is formed by applying an electrode material, such as Al or Ag, to the outermost surface of the cell main body by screen printing, or by vapor-depositing the electrode material on the outermost surface. - In
process 18 shown inFIG. 18 , the cell main body, on which the electrode material laminated, is immersed in an organic solvent, such as acetone. The photoresist, which is theprotective film 12, is dissolved in the organic solvent, so that the electrode material attached on the photoresist is removed together with the photoresist. The electrode material is selectively attached only in the opening section, and thereby thesurface electrode 13 is formed on thecontact layer 3, so that the thin film compound semiconductor solar cell is formed. - In
process 19 shown inFIG. 19 , after the formation of thesurface electrode 13, the thin film compound semiconductor solar cell is separated from the reinforcingmaterial 9. As the separation method, when the UV separation type material is used as the adhesive material, a method is used, in which the reinforcingmaterial 9 is separated from the cell main body by irradiating UV light by using a UV irradiation apparatus. - In
process 20 shown inFIG. 20 , after the separation of the reinforcingmaterial 9, thesurface electrode 13 is annealed. By performing the heat treatment, it is possible to reduce the contact resistance between thecontact layer 3 and thesurface electrode 13, and to improve the adhesive property between thecontact layer 3 and thesurface electrode 13. Next, the thin film compound solar cell formed in the wafer is separated into a plurality of solar cell elements. As the separation method, a method is used, in which the thin film compound solar cell is fixed to a stage by vacuum suction, or the like, and in which the opening section formed by the mesa-etching is cut by a scriber so that the plurality of solar cell elements are formed. - Finally, a metallic ribbon made of Ag, or the like, for establishing electrical connection between the respective elements, is connected by welding, or the like, to an electrode pad on the electrode of each of the solar cell elements.
- In the thin film compound solar cell manufactured by the manufacturing method as described above, the reinforcing
material 9 is directly bonded to therear surface film 8 as the base material without using an adhesive, such as wax. Thereby, a solvent for separating the reinforcingmaterial 9 need not be used, so that it is possible to prevent the problem that therear surface film 8 is separated by the solvent. Therear surface film 8 has heat resistance capable of withstanding a temperature higher than the annealing temperature of thesurface electrode 13, and hence it is possible to anneal thesurface electrode 13 after the rear surface film S is formed on therear surface electrode 7. - When the
surface electrode 13 and therear surface electrode 7 are annealed, the adhesive property of the electrodes with the cell main body is improved, so as to prevent each of the electrodes from being separated. Further, the contact resistance between the electrodes and the compound semiconductor layer can be reduced, so that the conversion efficiency is increased. - Further, the structure, in which the
surface electrode 13 is not covered with a surface film, is adopted, and hence thesurface electrode 13 is exposed. Thus, after thesubstrate 1 is removed, the metallic ribbon can be connected, and hence it is not necessary that, as in the conventional case, the metallic ribbon is protected when the substrate is removed. As a result, the number of processes can be reduced. - Further, a highly heat-resistant film, such as polyimide, is used as the base material, and thereby the film itself serves as a supporting body. Therefore, even when an external force is applied, the photovoltaic cell is prevented from being broken. Further, since the amount of warpage of the photovoltaic cell is changed according to the thickness of the film, the warpage of the cell can be reduced in such a manner that, when the film is formed, the thickness of the film is adjusted over the whole cell according to the thickness of the cell.
- Note that the present invention is not limited to the above described embodiment, but numerous modifications and changes can be obviously made therein without departing from the spirit and scope of the present invention. In another method for manufacturing a thin film compound solar cell, after
process 4 described above, thesubstrate 1 is separated from the cell main body, and the etching-stop layer 2 is removed. Then, the cell main body is mesa-etched as shown inFIG. 21 . A protective film made of a photoresist is formed on thecontact layer 3, and the patterning for forming the surface electrode is performed. An electrode material is laminated on the protective film and on thecontact layer 3 in the opening section. When the protective film is removed, thesurface electrode 13 is formed as shown inFIG. 22 . - Thereafter, as shown in
FIG. 23 , thecontact layer 3 is etched by the contact layer etching. At this time, thesurface electrode 13 is used as an etching mask. Subsequently, the reinforcingmaterial 9 is separated from the cell main body, and thesurface electrode 13 is annealed. Then, the thin film compound solar cell is separated into a plurality of solar cell elements, and the metallic ribbon is finally connected to each of the solar cell elements. - With this manufacturing method, the
surface electrode 13 serves as a protective film in the contact layer etching. Thus, as compared with the above-described manufacturing method, the process of forming the protective film used to perform the contact layer etching can be eliminated, and hence the number of processes can be reduced. - Further, in another method for manufacturing the rear surface film which is the base material, the rear surface film is formed by applying and sintering a solution of polyamic acid which is a polyimide precursor. That is, a solution of varnish-like polyamic acid is applied on the rear surface electrode, and is annealed stepwise so that a polyimide film is formed.
- Specifically, the polyamic acid solution is applied on the rear surface electrode by a spin-coating method, or the like. Thereafter, when annealing is first performed at 120° C. for one hour, the solvent of polyamic acid is evaporated, and the solution is temporarily cured. Then, the annealing temperature is increased stepwise. Finally, the annealing temperature is increased to the temperature at which the polyamic acid is polymerized and changed to a polyimide film. By this main curing, the polyimide film is formed.
- The reason for performing the annealing stepwise in this way is that, when the annealing is performed from the beginning at a temperature at which the polyamic acid starts to be polymerized, the surface layer of the polyamic acid solution is cured prior to the curing in the inside of the polyamic acid solution, with the result that an air bubble included in the solution at the time of annealing is left in the inside of the polyamic acid solution, and that the air bubble left in the inside of the polyamic acid solution is expanded to form a portion at which the rear surface electrode is not in close contact with the polyimide film. In addition, when the polyamic acid solution is rapidly cured, the contraction degree of the surface layer portion of the formed polyimide film becomes larger than the contraction degree in the inside of the polyimide film, so that the amount of warpage of the polyimide film is increased and thereby the photovoltaic cell is greatly warped. Thus, when the annealing temperature is increased stepwise as described above, the air bubble is prevented from being generated in the inside of the polyamic acid solution and the difference in the contraction degree between the surface layer portion and the inside of the polyimide film can also be prevented from occurring.
Claims (7)
1-11. (canceled)
12. A method for manufacturing a thin film compound solar cell having a cell main body in which at least one PN junction is formed by a plurality of compound semiconductor layers, each having a different chemical composition, the method comprising: a process of forming an etching-stop layer for suppressing infiltration of an etching solution from the side of a substrate, a contact layer, an emitter layer made of a first conductivity type compound semiconductor, a base layer forming a PN junction with the emitter layer, and a buffer layer; a process of forming a rear surface electrode on the surface on the compound semiconductor layer; a process of annealing the rear surface electrode; a process of forming a base material made of a polyimide film by applying and annealing polyimide on the rear surface electrode; a process of attaching a reinforcing material on the base material; a process of separating and removing the substrate from the cell main body; a process of forming a surface electrode; a process of removing the etching stop layer exposed by separating and removing, a process of etching the contact layer in a predetermined pattern, a process of mesa-etching, a process of forming a surface electrode on the mesa-etched contact layer; a process of separating the reinforcing material; and a process of annealing the surface electrode.
13. A method for manufacturing a thin film compound solar cell having a cell main body in which at least one PN junction is formed by a plurality of compound semiconductor layers, each having a different chemical composition, the method comprising: a process of forming an etching-stop layer for suppressing infiltration of an etching solution from the side of a substrate, a contact layer, an emitter layer made of a first conductivity type compound semiconductor, a base layer forming a PN junction with the emitter layer, and a buffer layer; a process of forming a rear surface electrode on the surface on the compound semiconductor layer; a process of annealing the rear surface electrode; a process of forming a base material made of a polyimide film by applying and annealing polyimide on the rear surface electrode; a process of attaching a reinforcing material on the base material; a process of separating and removing the substrate from the cell main body; a process of forming a surface electrode; a process of removing the etching stop layer exposed by separating and removing, a process of etching the contact layer in a predetermined pattern, a process of mesa-etching, a process of, after forming the surface electrode on the contact layer, etching the contact layer using the surface electrode as an etching mask, a process of separating the reinforcing material; and a process of annealing the surface electrode.
14. The method for manufacturing the thin film compound solar cell according to claim 12 , wherein the polyimide film is formed by applying and sintering a solution of polyamic acid which is a polyimide precursor.
15. The method for manufacturing the thin film compound solar cell according to claim 12 , wherein the thickness of the polyimide film is set to 15 μm or less.
16. A thin film compound solar cell comprising: a compound semiconductor layer in which at least one PN junction is formed; a surface electrode formed on one surface of the compound semiconductor layer; a polyimide film formed on the other surface of the compound semiconductor layer; and a rear surface electrode sandwiched between the compound semiconductor layer and the polyimide film.
17. The thin film compound solar cell according to claim 16 , wherein the compound semiconductor layer is made of an epitaxially grown single crystal thin film.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2009044415 | 2009-02-26 | ||
JP2009-044415 | 2009-02-26 | ||
PCT/JP2010/052655 WO2010098293A1 (en) | 2009-02-26 | 2010-02-22 | Method for manufacturing thin film compound solar cell |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2010/052655 A-371-Of-International WO2010098293A1 (en) | 2009-02-26 | 2010-02-22 | Method for manufacturing thin film compound solar cell |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/060,985 Division US9070819B2 (en) | 2009-02-26 | 2013-10-23 | Method for manufacturing thin film compound solar cell |
Publications (1)
Publication Number | Publication Date |
---|---|
US20110303281A1 true US20110303281A1 (en) | 2011-12-15 |
Family
ID=42665500
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/202,678 Abandoned US20110303281A1 (en) | 2009-02-26 | 2010-02-22 | Method for manufacturing thin film compound solar cell |
US14/060,985 Expired - Fee Related US9070819B2 (en) | 2009-02-26 | 2013-10-23 | Method for manufacturing thin film compound solar cell |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/060,985 Expired - Fee Related US9070819B2 (en) | 2009-02-26 | 2013-10-23 | Method for manufacturing thin film compound solar cell |
Country Status (4)
Country | Link |
---|---|
US (2) | US20110303281A1 (en) |
EP (1) | EP2403003B1 (en) |
JP (1) | JP5554772B2 (en) |
WO (1) | WO2010098293A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8912617B2 (en) * | 2011-10-27 | 2014-12-16 | Solar Junction Corporation | Method for making semiconductor light detection devices |
US9142615B2 (en) | 2012-10-10 | 2015-09-22 | Solar Junction Corporation | Methods and apparatus for identifying and reducing semiconductor failures |
US9263611B2 (en) | 2011-11-17 | 2016-02-16 | Solar Junction Corporation | Method for etching multi-layer epitaxial material |
CN112349796A (en) * | 2019-08-06 | 2021-02-09 | 东泰高科装备科技有限公司 | Gallium arsenide battery and preparation method thereof |
US11563132B2 (en) | 2018-01-29 | 2023-01-24 | Kabushiki Kaisha Toshiba | Solar cell, multi-junction solar cell, solar cell module, and photovoltaic system |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5840544B2 (en) * | 2012-03-21 | 2016-01-06 | シャープ株式会社 | Thin film compound solar cell and manufacturing method thereof |
JP5980923B2 (en) * | 2012-06-26 | 2016-08-31 | シャープ株式会社 | Thin film solar cell and manufacturing method thereof |
JP2014017366A (en) * | 2012-07-09 | 2014-01-30 | Sharp Corp | Thin film compound solar battery cell and manufacturing method of the same |
DE112016004374T5 (en) * | 2015-09-28 | 2018-06-14 | Sharp Kabushiki Kaisha | A thin film compound semiconductor photovoltaic cell, a method of manufacturing a thin film compound semiconductor photovoltaic cell, thin film compound semiconductor photovoltaic cell array and manufacturing method thereof |
JP2019057536A (en) * | 2017-09-19 | 2019-04-11 | 株式会社東芝 | Solar cell, multi-junction type solar cell, solar cell module and photovoltaic power generation system |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4370510A (en) * | 1980-09-26 | 1983-01-25 | California Institute Of Technology | Gallium arsenide single crystal solar cell structure and method of making |
US4392297A (en) * | 1980-11-20 | 1983-07-12 | Spire Corporation | Process of making thin film high efficiency solar cells |
US4514579A (en) * | 1984-01-30 | 1985-04-30 | Energy Conversion Devices, Inc. | Large area photovoltaic cell and method for producing same |
US5538902A (en) * | 1993-06-29 | 1996-07-23 | Sanyo Electric Co., Ltd. | Method of fabricating a photovoltaic device having a three-dimensional shape |
US6410362B1 (en) * | 2000-08-28 | 2002-06-25 | The Aerospace Corporation | Flexible thin film solar cell |
US20080223436A1 (en) * | 2007-03-15 | 2008-09-18 | Guardian Industries Corp. | Back reflector for use in photovoltaic device |
US20080245409A1 (en) * | 2006-12-27 | 2008-10-09 | Emcore Corporation | Inverted Metamorphic Solar Cell Mounted on Flexible Film |
US20090020149A1 (en) * | 2007-07-16 | 2009-01-22 | Woods Lawrence M | Hybrid Multi-Junction Photovoltaic Cells And Associated Methods |
US20100200063A1 (en) * | 2009-02-12 | 2010-08-12 | Derek Djeu | Thin film solar cell |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4681654A (en) * | 1986-05-21 | 1987-07-21 | International Business Machines Corporation | Flexible film semiconductor chip carrier |
JPH08107281A (en) * | 1994-10-06 | 1996-04-23 | Sumitomo Bakelite Co Ltd | Multilayer flexible printed circuit board and its manufacture |
EP0849788B1 (en) * | 1996-12-18 | 2004-03-10 | Canon Kabushiki Kaisha | Process for producing semiconductor article by making use of a substrate having a porous semiconductor layer |
ES2149137B1 (en) * | 1999-06-09 | 2001-11-16 | Univ Madrid Politecnica | SOLAR PHOTOVOLTAIC SEMICONDUCTOR CELL OF INTERMEDIATE CELL. |
JP2002289884A (en) * | 2001-03-27 | 2002-10-04 | Sumitomo Electric Ind Ltd | Solar cell and solar cell device |
US8067687B2 (en) * | 2002-05-21 | 2011-11-29 | Alliance For Sustainable Energy, Llc | High-efficiency, monolithic, multi-bandgap, tandem photovoltaic energy converters |
JP4471584B2 (en) | 2003-04-28 | 2010-06-02 | シャープ株式会社 | Method for producing compound solar cell |
JP2007317834A (en) * | 2006-05-25 | 2007-12-06 | Toyobo Co Ltd | Film-like solar cell |
US8536445B2 (en) * | 2006-06-02 | 2013-09-17 | Emcore Solar Power, Inc. | Inverted metamorphic multijunction solar cells |
JP5257918B2 (en) * | 2007-04-23 | 2013-08-07 | シャープ株式会社 | Compound semiconductor solar cell |
US20090038679A1 (en) * | 2007-08-09 | 2009-02-12 | Emcore Corporation | Thin Multijunction Solar Cells With Plated Metal OHMIC Contact and Support |
-
2010
- 2010-02-22 US US13/202,678 patent/US20110303281A1/en not_active Abandoned
- 2010-02-22 JP JP2011501582A patent/JP5554772B2/en not_active Expired - Fee Related
- 2010-02-22 WO PCT/JP2010/052655 patent/WO2010098293A1/en active Application Filing
- 2010-02-22 EP EP10746174.1A patent/EP2403003B1/en not_active Not-in-force
-
2013
- 2013-10-23 US US14/060,985 patent/US9070819B2/en not_active Expired - Fee Related
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4370510A (en) * | 1980-09-26 | 1983-01-25 | California Institute Of Technology | Gallium arsenide single crystal solar cell structure and method of making |
US4392297A (en) * | 1980-11-20 | 1983-07-12 | Spire Corporation | Process of making thin film high efficiency solar cells |
US4514579A (en) * | 1984-01-30 | 1985-04-30 | Energy Conversion Devices, Inc. | Large area photovoltaic cell and method for producing same |
US5538902A (en) * | 1993-06-29 | 1996-07-23 | Sanyo Electric Co., Ltd. | Method of fabricating a photovoltaic device having a three-dimensional shape |
US6410362B1 (en) * | 2000-08-28 | 2002-06-25 | The Aerospace Corporation | Flexible thin film solar cell |
US20080245409A1 (en) * | 2006-12-27 | 2008-10-09 | Emcore Corporation | Inverted Metamorphic Solar Cell Mounted on Flexible Film |
US20080223436A1 (en) * | 2007-03-15 | 2008-09-18 | Guardian Industries Corp. | Back reflector for use in photovoltaic device |
US20090020149A1 (en) * | 2007-07-16 | 2009-01-22 | Woods Lawrence M | Hybrid Multi-Junction Photovoltaic Cells And Associated Methods |
US20100200063A1 (en) * | 2009-02-12 | 2010-08-12 | Derek Djeu | Thin film solar cell |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8912617B2 (en) * | 2011-10-27 | 2014-12-16 | Solar Junction Corporation | Method for making semiconductor light detection devices |
US9263611B2 (en) | 2011-11-17 | 2016-02-16 | Solar Junction Corporation | Method for etching multi-layer epitaxial material |
US9627561B2 (en) | 2011-11-17 | 2017-04-18 | Solar Junction Corporation | Method for etching multi-layer epitaxial material |
US9142615B2 (en) | 2012-10-10 | 2015-09-22 | Solar Junction Corporation | Methods and apparatus for identifying and reducing semiconductor failures |
US11563132B2 (en) | 2018-01-29 | 2023-01-24 | Kabushiki Kaisha Toshiba | Solar cell, multi-junction solar cell, solar cell module, and photovoltaic system |
CN112349796A (en) * | 2019-08-06 | 2021-02-09 | 东泰高科装备科技有限公司 | Gallium arsenide battery and preparation method thereof |
Also Published As
Publication number | Publication date |
---|---|
EP2403003A1 (en) | 2012-01-04 |
JPWO2010098293A1 (en) | 2012-08-30 |
WO2010098293A1 (en) | 2010-09-02 |
JP5554772B2 (en) | 2014-07-23 |
EP2403003A4 (en) | 2013-06-05 |
EP2403003B1 (en) | 2018-10-03 |
US9070819B2 (en) | 2015-06-30 |
US20140051205A1 (en) | 2014-02-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9070819B2 (en) | Method for manufacturing thin film compound solar cell | |
JP4343225B2 (en) | Solar cells | |
CN104617195B (en) | A kind of near-infrared luminous diode and its production method | |
JP2003282478A (en) | Method for alloying and method forming wire, method for forming display element, and method for manufacturing image display device | |
US20120012180A1 (en) | Back electrode type solar cell, connecting sheet, solar cell with connecting sheet, solar cell module, method of manufacturing solar cell with connecting sheet, and method of manufacturing solar cell module | |
JP2008166794A (en) | Inverted metamorphic solar cell mounted on flexible film | |
WO2007060744A1 (en) | Solar battery cell and method for manufacturing same | |
AU2006276661A1 (en) | Method for manufacturing photoelectric conversion element and the photoelectric conversion element | |
JP5232466B2 (en) | Photovoltaic device | |
CN102804405A (en) | Method for manufacturing photovoltaic modules comprising back-contact cells | |
JP2010157553A (en) | Interconnect sheet, solar cell with the interconnect cell, solar cell module, and method of manufacturing the solar cell with the interconnect sheet, and method of manufacturing the solar cell moidule | |
JP2004072021A (en) | Semiconductor device | |
JP2021177577A (en) | Manufacturing method of semiconductor element and semiconductor substrate | |
JPH114008A (en) | Manufacture of thin film solar battery | |
JP2014017366A (en) | Thin film compound solar battery cell and manufacturing method of the same | |
JP2013149773A (en) | Thin film compound solar cell manufacturing method | |
JP5980923B2 (en) | Thin film solar cell and manufacturing method thereof | |
WO2017057029A1 (en) | Thin-film compound solar cell, method for manufacturing thin-film compound solar cell, thin-film compound solar cell array, and method for manufacturing thin-film compound solar cell array | |
CN115315781A (en) | Method for manufacturing bonded wafer and bonded wafer | |
JP5034488B2 (en) | Manufacturing method of semiconductor device | |
JP2014103305A (en) | Solar cell element and method of manufacturing the same | |
WO2023021972A1 (en) | Provisionally bonded wafer and method for producing same | |
JP2007220931A (en) | Thin film compound solar cell, and its manufacturing method | |
JP4753816B2 (en) | Solar cell and manufacturing method thereof | |
JP3708342B2 (en) | Method for manufacturing light-emitting diode element |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SHARP KABUSHIKI KAISHA, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KODAMA, TOMOYA;REEL/FRAME:026785/0466 Effective date: 20110805 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |