WO2011155052A1 - Crystalline solar battery cell and process for production thereof - Google Patents

Crystalline solar battery cell and process for production thereof Download PDF

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Publication number
WO2011155052A1
WO2011155052A1 PCT/JP2010/059913 JP2010059913W WO2011155052A1 WO 2011155052 A1 WO2011155052 A1 WO 2011155052A1 JP 2010059913 W JP2010059913 W JP 2010059913W WO 2011155052 A1 WO2011155052 A1 WO 2011155052A1
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Prior art keywords
receiving surface
light
surface electrode
electrode
solar cell
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PCT/JP2010/059913
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French (fr)
Japanese (ja)
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崎尾　進
竹井　日出夫
一也 斎藤
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株式会社アルバック
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Priority to PCT/JP2010/059913 priority Critical patent/WO2011155052A1/en
Priority to JP2012519181A priority patent/JPWO2011155052A1/en
Publication of WO2011155052A1 publication Critical patent/WO2011155052A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—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
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/068—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 potential barriers 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
    • 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
    • Y02E10/547—Monocrystalline silicon PV cells

Definitions

  • the present invention relates to a method for forming a light-receiving surface electrode of a crystalline solar cell, particularly a solar cell using a silicon substrate.
  • FIG. 5A is a schematic view showing the cell structure of a conventional crystalline solar cell
  • FIG. 5B is a plan view showing the cell structure of the conventional crystalline solar cell.
  • the cell 101 of the conventional crystalline solar cell has n + on the front side surface (the surface on which light 100 is incident) of the silicon substrate 103 on which the texture 102 is formed.
  • a type semiconductor layer 104 and an antireflection film 105 are sequentially formed. Further, on the antireflection film 105, a light receiving surface electrode 106 (a bus bar electrode 106a and a finger electrode 106b) extending in a straight line is formed on the n + type semiconductor layer 104. It is formed to be connected.
  • a p + type semiconductor layer 107 and a back electrode 108 are sequentially formed on the back side surface of the silicon substrate 103.
  • the light-receiving surface electrode 106 of a crystalline solar cell has been formed by screen printing using a silver paste.
  • the technique has a problem that the aperture ratio is as low as about 93%.
  • the screen plate and the surface of the solar cell are in contact with each other, so that there is a problem that the substrate is cracked or the mesh portion made of stainless steel comes into contact with the silicon layer to cause damage.
  • the prior art relating to the present invention includes the following.
  • the present invention has been made to solve the above-described problems of the conventional technology, and an object of the present invention is to provide a technology for forming a light receiving surface electrode of a solar battery cell that can improve an aperture ratio. It is in.
  • Another object of the present invention is to provide a technology for forming a light receiving surface electrode of a solar battery cell that does not damage the silicon layer.
  • the present invention is also effective when the bonding wire is made of gold, silver, copper, aluminum, palladium, or an alloy thereof.
  • the present invention is also effective when the light-receiving surface electrode is electrically connected to the first conductivity type layer of the semiconductor substrate via a connection film made of a conductive sintered body containing glass frit. is there.
  • the light receiving surface electrode includes a first light receiving surface electrode provided on the first conductivity type layer of the semiconductor substrate, and a second light receiving surface electrode provided on the first light receiving surface electrode.
  • the first light-receiving surface electrode is electrically connected to the first conductivity type layer of the semiconductor substrate through a first connection film made of the conductive sintered body, and It is also effective when the second light receiving surface electrode is electrically connected to the first light receiving surface electrode via the second connection film made of the conductive sintered body.
  • an antireflection film is provided on the first conductive type layer of the semiconductor substrate having the first conductive type layer on the light incident side surface side and the second conductive type layer on the back side.
  • the light-receiving surface electrode composed of a bonding wire made of a conductor is used as the solar cell substrate. It is a method for manufacturing a crystalline solar battery cell having a step of fixing the light receiving surface electrode to the first conductivity type layer of the semiconductor substrate while being fixed to the top.
  • the light receiving surface electrode includes first and second light receiving surface electrodes, and a step of applying and drying the conductive paste on the antireflection film to form a first connection film; Disposing the first light-receiving surface electrode on the first connection film; sintering the first connection film; and applying and drying the conductive paste on the first light-receiving surface electrode. It is also effective in the case of having a step of forming the second connection film and a step of sintering the second connection film.
  • a light receiving surface electrode in which a conductive film is applied to the bonding wire and dried to form a connection film is prepared, and the light receiving surface electrode is disposed on the solar cell substrate; It is also effective when it has the process of sintering this connection film
  • the process of applying the conductive paste is also effective when the dispenser method or the ink jet method is used.
  • the light-receiving surface electrode is constituted by a bonding wire made of a conductor, and the light-receiving surface electrode is formed when an electrode having an equivalent wiring resistance is formed as compared with the light-receiving surface electrode by screen printing of the prior art
  • the width of can be made very small.
  • the aperture ratio of the solar cells which was about 93% in the prior art, can be significantly improved to about 99%.
  • the conductive paste coating means does not come into contact with the solar cell substrate.
  • the substrate is not broken and the silicon layer is not damaged.
  • the light-receiving surface electrode made of a bonding wire is disposed on the antireflection film via the conductive paste, and in this state, the first connection film made of the conductive paste containing glass frit is baked.
  • the light-receiving surface electrode and the first conductive type layer of the semiconductor substrate are reliably electrically connected through the sintered connection film by fire-through due to the reaction between the antireflection film and the first connection film. can do.
  • the aperture ratio of the crystalline solar cell can be greatly improved.
  • SYMBOLS 1 Substrate for solar cells, 10 ... Silicon substrate (semiconductor substrate), 11 ... n ⁇ +> type semiconductor layer (first conductivity type layer), 12 ... Antireflection film, 13 ... p + type semiconductor layer (second conductivity type layer) ), 14 ... Back electrode layer, 15 ... First connection film, 16 ... First sintered connection film, 17 ... Second connection film, 18 ... Second sintered connection film, 21 ... Finger electrode (first electrode) 1 light-receiving surface electrode), 22 ... bus bar electrode (second light-receiving surface electrode), 30 ... crystalline solar cell
  • FIGS. 1 (a) to 1 (d) are cross-sectional views (part 1) showing the manufacturing process of the crystalline solar cell according to the present embodiment
  • FIGS. 2 (a) to (c) are the crystals of the same embodiment.
  • FIG. 3 is a plan view of the crystalline solar battery cell of the same embodiment. As shown in FIG.
  • n + type semiconductor layer 11 that is a first conductivity type layer and an antireflection film 12 are sequentially formed, and a p + type semiconductor layer 13 that is a second conductivity type layer and a back electrode layer 14 are sequentially formed on the back side thereof.
  • a solar cell substrate 1 is prepared.
  • the material of the antireflection film 12 is not particularly limited, but from the viewpoint of ensuring the reactivity with the conductive paste during sintering described later, silicon nitride (SiN), silicon oxide (SiO 2 ) and titanium oxide (TiO 2 ) can be preferably used. Further, the thickness of the antireflection film 12 is not particularly limited, but is preferably 100 to 500 nm from the viewpoint of reducing the reflectance. In addition, as a material of the back electrode layer 14, for example, a silver (Ag) paste can be suitably used.
  • first connection films (connection films) 15 made of a conductive paste described later are applied and formed on the surface of the antireflection film 12 at a predetermined interval. Thereafter, the first connection film 15 is dried.
  • the position where the first connection film 15 is formed by coating is a position corresponding to a position where a finger electrode (first light-receiving surface electrode) 21 described later is provided, for example, a length equivalent to the length of the finger electrode 21. Furthermore, it is good to apply and form.
  • the method for applying the first connection film 15 is not particularly limited, but from the viewpoint of forming the first connection film 15 with high accuracy, a method using a dispenser or a method using an ink jet is employed.
  • the width of the first connection film 15 is not particularly limited, but from the viewpoint of further improving the aperture ratio of the solar battery cell, the width of the first connection film 15 is set to be larger than the width of the finger electrode 21. It is preferable to make it small. Specifically, the width of the first connection film 15 is preferably set to 5 to 15 ⁇ m.
  • the thickness of the first connection film 15 is not particularly limited, but from the viewpoint of securing sufficient adhesive strength and further improving the aperture ratio of the solar battery cell, the antireflection film 12 is provided. It is preferable to make it thicker. Specifically, it is preferable to set the thickness of the first connection film 15 to 500 to 10,000 nm.
  • the conductive paste used for the first connection film 15 for example, a conductive paste described in JP-A-2006-295197 can be suitably used.
  • the conductive paste used in the present invention contains a conductive metal, an inorganic binder, and an organic vehicle.
  • the conductive metal that can be contained in the conductive paste used in the present invention include silver particles, and silver particles are most preferable.
  • the silver particles are preferably in flake form or powder form.
  • the particle size of the silver particles of the conductive paste is not particularly limited. However, the influence of the sintering characteristics (silver particles having a large particle size is larger than the speed of silver particles having a small particle size). Sintering at a slower speed) and ease of application, the average particle size of the silver particles is preferably 3.0-15.0 ⁇ m, more preferably 5.0-11.0 ⁇ m.
  • the particle size of the silver particles is smaller than 3.0 ⁇ m, the silver conductive paste exhibits a steep sintering behavior, and cracks between the two electrodes are caused by the mismatch of the sintering rate with the aluminum paste. Tend to occur.
  • the particle size of the silver particles is larger than 15.0 ⁇ m, the conductivity is lowered and the strength of the electrode film is reduced. This is because sintering does not proceed sufficiently.
  • silver particles contained in the conductive paste it is preferable that silver has a high purity (99% or more), but a substance having a purity of less than 99% may also be used according to the electrical requirements of the electrode pattern. it can.
  • the most preferable conductive metal in the conductive paste is silver particles, but conductive metals other than silver can be used similarly.
  • metals such as copper (Cu), gold (Au), palladium (Pd) and platinum (Pt) are useful.
  • alloys or mixtures of the aforementioned metals are useful in the present invention as well.
  • Cu—Au, Ag—Pd, Pt—Au, or the like can be used.
  • the content of the conductive metal in the conductive paste is not particularly limited as long as it is an amount that can achieve the object of the present invention. From the viewpoint of ensuring conductivity, It is preferably contained in an amount of 40 to 93% by mass based on the weight of the conductive paste.
  • aluminum (Al) can be added to the conductive paste for the purpose of improving desired characteristics.
  • the conductive paste used in the present invention contains an inorganic binder.
  • an inorganic binder a glass frit (fine particles) having a softening point of 450 to 550 ° C. can be suitably used.
  • Such a glass frit can bake the conductive paste at 600 to 800 ° C., appropriately sinter and wet, and properly adhere to the silicon substrate 10.
  • the softening point of the glass frit is lower than 450 ° C., sintering becomes excessive, and the effects of the present invention may not be sufficiently obtained.
  • the softening point of the glass frit is higher than 550 ° C., sufficient adhesion strength may not be exhibited, and liquid phase sintering of silver may not be promoted. This is because a sufficient melt flow does not occur during sintering.
  • the softening point is defined by ASTM (American Society for Testing and Materials) C338-57 fiber elongation method.
  • the glass frit contained in the conductive paste is not particularly limited, but considering both the softening point range and the glass fusibility, for example, silicate glass, lead borosilicate glass, etc. are suitable. Can be used. It is also possible to use glass that does not contain lead, such as zinc borosilicate.
  • the content of the glass frit as the inorganic binder is not particularly limited as long as it can achieve the object of the present invention, but is 2.0 to 10 based on the total weight of the conductive paste.
  • the content is preferably 0.0 mass%, more preferably 3.0 to 6.0 mass%. If the glass frit content is less than 2.0% by mass, the adhesive strength may be insufficient. On the other hand, if the glass frit content is more than 10.0% by mass, for example, post-processing is performed. The soldering process may be hindered by glass floating or the like.
  • the conductive paste used in the present invention contains an organic vehicle.
  • An inert liquid can be used as the organic vehicle contained in the conductive paste.
  • Such inert liquids include organic liquids such as alcohols; alcohol esters (such as acetate or propionate); starch (such as pine oil and terpineol); resins (such as polymethacrylate).
  • organic liquids such as alcohols; alcohol esters (such as acetate or propionate); starch (such as pine oil and terpineol); resins (such as polymethacrylate).
  • various solutions such as a pine oil solution of ethyl cellulose or a solution of ethylene glycol monobutyl ether monoacetate, or a terpineol solution of ethyl cellulose can be mentioned.
  • a preferable content of the organic vehicle is 5 to 50% by mass based on the total weight of the conductive paste.
  • a thickener, a stabilizer, and other general additives can be added to the conductive paste used in the present invention.
  • a tackifier agent thickener
  • a stabilizer and the like can be added, or a dispersant, a viscosity modifier and the like can be added as other general additives.
  • the amount of the additive is determined based on the properties of the finally obtained conductive paste, and can be appropriately determined by the manufacturer involved. Several types of additives can also be used.
  • the conductive paste used in the present invention preferably has a viscosity within a predetermined range.
  • it can be achieved by adding the above-described tackifier (thickener).
  • the electrically conductive paste used for this invention can be manufactured by mixing each component mentioned above with a well-known 3 roll kneader.
  • the viscosity of the conductive paste used in the present invention is not particularly limited, but is measured at a rotation speed of 10 rpm and a temperature of 25 ° C. using a Brookfield HBT viscometer and a utility cup using a # 14 spindle. At this time, it is preferable to adjust the pressure to 50 to 300 Pa ⁇ S.
  • a plurality of first connection films 15 made of the conductive paste described above are applied and formed on the antireflection film 12, and then the first connection films 15 are dried.
  • a preferable drying temperature is 180 ° C. or less.
  • finger electrodes 21 made of bonding wires are aligned and placed (placed) on each of the first connection films 15.
  • the material of the bonding wire constituting the finger electrode 21 is not particularly limited, but gold (Au), silver (Ag), copper (Cu), aluminum (Al), palladium (Pd) Or those made of these alloys can be suitably used.
  • the cross-sectional shape of the bonding wire which comprises the finger electrode 21 is a perfect circle shape, and it is so preferable that the diameter is small from a viewpoint of improving an aperture ratio.
  • the diameter is preferably 10 to 100 ⁇ m.
  • the solar cell substrate 1 on which the finger electrodes 21 are arranged is heated and sintered in the air at a temperature of 600 to 800 ° C. for 2 to 15 minutes.
  • the finger electrode 21 may be pressurized.
  • the glass frit contained in the conductive paste of the first connection film 15 reacts with the substance of the antireflection film 12, and the antireflection film 12 melts, as shown in FIG.
  • the first connection film 16 (hereinafter referred to as “first sintered connection film”) 16 is buried in the antireflection film 12 (fire-through).
  • each finger electrode 21 is fixed to the first sintered connection film 16 by the above-described sintering step.
  • the first sintered connection film 16 and the n + -type semiconductor layer 11 come into contact with each other and are electrically connected to each other, so that the finger electrode 21 passes through the first sintered connection film 16 that is a connection film.
  • n + type semiconductor layer 11 are electrically connected.
  • the width of the first sintered connection film 16 is smaller than the width of each finger electrode 21.
  • the silver paste of the back surface electrode layer 14 is also baked by the sintering process described above, and the sintered back surface electrode layer 14a is formed.
  • the second connection film 17 made of the above-described conductive paste is applied and formed on each finger electrode 21, and then these are dried.
  • the method for applying the second connection film 17 is not particularly limited, but from the viewpoint of forming the second connection film 17 with high accuracy, a method using a dispenser or a method using an ink jet is employed. It is preferable.
  • the width of the second connection film 17 is not particularly limited, but from the viewpoint of further improving the aperture ratio of the solar battery cell, the width of the second connection film 17 is larger than the width of the bus bar electrode 22 described later. It is preferable to reduce the length (the length in the direction orthogonal to the direction in which the bus bar electrode 22 extends).
  • the width of the second connection film 17 is preferably set to 5 to 15 ⁇ m.
  • a preferable drying temperature of the second connection film 17 is 180 ° C. or lower.
  • the thickness of the first connection film 15 is preferably set to 500 to 10,000 nm.
  • the bus bar electrodes 22 made of bonding wires are aligned and placed (placed) on each of the second connection films 17.
  • the material of the bonding wire constituting the bus bar electrode 22 is not particularly limited, but gold (Au), silver (Ag), copper (Cu), aluminum (Al), palladium (Pd) Or those made of these alloys can be suitably used. Among these, it is preferable to use silver (Ag) from the viewpoint of improving conductivity.
  • the cross-sectional shape of the bonding wire which comprises the bus-bar electrode 22 is a perfect circle shape, From the viewpoint of improving the aperture ratio of a photovoltaic cell, the diameter is so preferable that it is small. However, considering the strength required for the electrode and the size of the wiring resistance, the diameter is preferably 120 to 500 ⁇ m or less.
  • the solar cell substrate 1 on which the bus bar electrodes 22 are arranged is heated and sintered in air at a temperature of 600 to 800 ° C. for 2 to 15 minutes.
  • the bus bar electrode 22 may be pressurized.
  • the second connection film 17 is sintered, and each finger electrode 21 is fixed to the sintered second connection film 18 (hereinafter referred to as “second sintered connection film”).
  • each bus bar electrode 22 is fixed to the second sintered connection film 18.
  • the bus bar electrode 22 and the finger electrode 21 are electrically connected via the second sintered connection film 18 which is a connection film, and the silicon substrate 10 is connected.
  • a crystalline solar cell 30 having first and second light-receiving surface electrodes that are electrically connected to each other is obtained.
  • the finger electrode 21 and the bus bar electrode 22 that are light receiving surface electrodes are configured by bonding wires made of conductors, compared with the light receiving surface electrodes by screen printing of the prior art.
  • the width of the light receiving surface electrode can be made very small.
  • the aperture ratio of the crystalline solar battery cell can be greatly improved.
  • the means for applying the conductive paste is the solar cell substrate. 1 is not touched, and the substrate is not broken and the silicon layer is not damaged as in the case of conventional screen printing.
  • the finger electrode 21 made of a bonding wire is disposed on the antireflection film 12 via a conductive paste, and in this state, the first connection made of a conductive paste containing glass frit is used. Since the film 15 is sintered, the finger electrode 21 and the n + type semiconductor of the semiconductor substrate 10 are interposed through the first sintered connection film 16 by fire-through due to the reaction between the antireflection film 12 and the first connection film 15. The layer 11 can be reliably electrically connected.
  • FIGS. 1 (a) to 4 (c) show other embodiments of the present invention.
  • the conductive paste is applied, dried and sintered, so that on the solar cell substrate 1,
  • the finger electrode 21 and the n + type semiconductor layer 11 are electrically connected through the first sintered connection film 16.
  • a plurality of second connection films 17 made of the conductive paste are applied and formed on the surface of the bus bar electrode 22 at a predetermined interval, and then dried.
  • the position where the second connection film 17 on the surface of the bus bar electrode 22 is formed by application is preferably a connection portion with the finger electrode 21 provided on the solar cell substrate 1.
  • the method of applying the second connection film 17 is not particularly limited, but from the viewpoint of forming the second connection film 17 on the surface of the bus bar electrode 22 with high accuracy, a method using a dispenser or inkjet It is preferable to adopt the method according to Further, the width of the second connection film 17 is not particularly limited, but from the viewpoint of further improving the aperture ratio of the solar battery cell, the length of the second connection film 17 is larger than the width of the bus bar electrode 22. It is preferable to reduce (the length in the direction orthogonal to the direction in which the bus bar electrode 22 extends). On the other hand, the thickness of the second connection film 17 is not particularly limited, but it is 500 to 10,000 nm from the viewpoint of securing sufficient adhesive strength and further improving the aperture ratio of the solar battery cell. It is preferable to set.
  • the bus bar electrode 22 is arranged (placed) so that the finger electrode 21 on the first layer and the second connection film 17 are in contact with each other. Thereafter, the solar cell substrate 1 is heated and sintered in air at a temperature of 600 to 800 ° C. for 2 to 15 minutes. In this case, the bus bar electrode 22 may be pressurized. As a result, as in the above embodiment, the second connection film 17 is sintered, and each finger electrode 21 is fixed to the second sintered connection film 18 as shown in FIG.
  • each bus bar electrode 22 is fixed to the second sintered connection film 18.
  • the bus bar electrode 22 and the finger electrode 21 are electrically connected via the second sintered connection film 18 and electrically connected to the silicon substrate 10 as in the above embodiment.
  • the crystalline solar cell 30 which has a 2nd light-receiving surface electrode is obtained.
  • the present invention is not limited to the above-described embodiment, and various changes can be made.
  • the second connection film 17 is formed by applying a conductive paste to the bus bar electrode 22, but the present invention is not limited to this.
  • the first connecting film 15 can be formed by applying a conductive paste to the finger electrode 21 and sintered.
  • a connection film can be formed on the entire surface of the finger electrode 21 and the bus bar electrode 22, respectively.
  • the semiconductor substrate used in the present invention either a single crystal silicon substrate or a polycrystalline silicon substrate can be used as the semiconductor substrate used in the present invention.

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Abstract

Disclosed is a technique for producing a light receiving surface electrode for a crystalline solar battery cell, which can improve an aperture ratio and does not damage a silicon layer. Specifically disclosed is a crystalline solar battery cell comprising: a silicon substrate (10) which has an n+-type semiconductor layer (11) on the front surface side on the light incident side thereof and a p+-type semiconductor layer (13) on the back surface side thereof; an antireflective film (12), and a finger electrode (21) and a bus bar electrode (22) that serve as light-receiving surface electrodes, all of which are formed on the n+-type semiconductor layer (11) on the silicon substrate (10); and a sintered back surface electrode layer (14a) which is formed on the p+-type semiconductor layer (13) on the silicon substrate (10). Each of the finger electrode (21) and the bus bar electrode (22) is composed of a bonding wire comprising an electrically conductive material. The bonding wire is composed of gold, silver, copper, aluminum, palladium or an alloy thereof.

Description

結晶系太陽電池セル及びその製造方法Crystalline solar cell and manufacturing method thereof
　本発明は、結晶系太陽電池、特に、シリコン基板を用いた太陽電池の受光面電極の形成方法に関するものである。 The present invention relates to a method for forming a light-receiving surface electrode of a crystalline solar cell, particularly a solar cell using a silicon substrate.
　図５（ａ）は、従来の結晶系太陽電池のセル構造を示す概略図、図５（ｂ）は、従来の結晶系太陽電池のセル構造を示す平面図である。
　図５（ａ）（ｂ）に示すように、従来の結晶系太陽電池のセル１０１は、テクスチャー１０２が形成されたシリコン基板１０３の表側面（光１００が入射する側の面）に、ｎ+型半導体層１０４、反射防止膜１０５が順次形成され、さらに、反射防止膜１０５上には、直線状に延びる受光面電極１０６（バスバー電極１０６ａ及びフィンガー電極１０６ｂ）が、ｎ+型半導体層１０４と接続されるように形成されている。
　一方、シリコン基板１０３の裏側面には、ｐ+型半導体層１０７、裏面電極１０８が順次形成されている。
　従来、結晶系太陽電池の受光面電極１０６は、銀ペーストを用いたスクリーン印刷で形成していた。
　しかし、従来技術においては、受光面電極１０６の抵抗値を低くするために、フィンガー電極１０６ｂの線幅を１００μｍ程度、バスバー電極１０６ａの線幅を２ｍｍ程度と大きくする必要があり、その結果、従来技術では開口率が９３％程度と低いという課題があった。
　また、スクリーン印刷では、スクリーン版と太陽電池の表面が接触するため、基板が割れたり、ステンレスからなるメッシュ部分がシリコン層に当接してダメージを与えるという問題もあった。
　なお、本発明に関する先行技術としては、以下に示すようなものがある。 FIG. 5A is a schematic view showing the cell structure of a conventional crystalline solar cell, and FIG. 5B is a plan view showing the cell structure of the conventional crystalline solar cell.
As shown in FIGS. 5A and 5B, the cell 101 of the conventional crystalline solar cell has n + on the front side surface (the surface on which light 100 is incident) of the silicon substrate 103 on which the texture 102 is formed. A type semiconductor layer 104 and an antireflection film 105 are sequentially formed. Further, on the antireflection film 105, a light receiving surface electrode 106 (a bus bar electrode 106a and a finger electrode 106b) extending in a straight line is formed on the n + type semiconductor layer 104. It is formed to be connected.
On the other hand, a p + type semiconductor layer 107 and a back electrode 108 are sequentially formed on the back side surface of the silicon substrate 103.
Conventionally, the light-receiving surface electrode 106 of a crystalline solar cell has been formed by screen printing using a silver paste.
However, in the prior art, in order to reduce the resistance value of the light-receiving surface electrode 106, it is necessary to increase the line width of the finger electrode 106b to about 100 μm and the line width of the bus bar electrode 106a to about 2 mm. The technique has a problem that the aperture ratio is as low as about 93%.
Further, in the screen printing, the screen plate and the surface of the solar cell are in contact with each other, so that there is a problem that the substrate is cracked or the mesh portion made of stainless steel comes into contact with the silicon layer to cause damage.
The prior art relating to the present invention includes the following.
特開昭４９－１１４８８７号公報Japanese Patent Laid-Open No. 49-114887 特開２００６－２９５１９７号公報JP 2006-295197 A 特開２００１－１１８４２５号公報JP 2001-118425 A
　本発明は、このような従来の技術の課題を解決するためになされたもので、その目的とするところは、開口率を向上することができる太陽電池セルの受光面電極形成技術を提供することにある。 The present invention has been made to solve the above-described problems of the conventional technology, and an object of the present invention is to provide a technology for forming a light receiving surface electrode of a solar battery cell that can improve an aperture ratio. It is in.
　また、本発明の他の目的は、シリコン層にダメージを与えることのない太陽電池セルの受光面電極形成技術を提供することにある。 Another object of the present invention is to provide a technology for forming a light receiving surface electrode of a solar battery cell that does not damage the silicon layer.
　上記課題を解決するためになされた本発明は、光入射側の表面側に第１導電型層を有し、かつ、裏面側に第２導電型層を有する半導体基板を備え、前記半導体基板の第１導電型層上に、反射防止膜と、受光面電極とが設けられるとともに、前記半導体基板の第２導電型層上に接続用裏面電極が設けられ、前記受光面電極が、導体からなるボンディングワイヤによって構成されている結晶系太陽電池セルである。
　本発明では、前記ボンディングワイヤが、金、銀、銅、アルミニウム、パラジウム、又はこれらの合金からなる場合にも効果的である。
　本発明では、前記受光面電極が、ガラスフリットを含有する導電性焼結体からなる接続膜を介して前記半導体基板の第１導電型層に電気的に接続されている場合にも効果的である。
　本発明では、前記受光面電極が、前記半導体基板の第１導電型層上に設けられた第１の受光面電極と、当該第１の受光面電極上に設けられた第２の受光面電極とを有し、前記第１の受光面電極が、前記導電性焼結体からなる第１の接続膜を介して前記半導体基板の前記第１導電型層に電気的に接続されるとともに、前記第２の受光面電極が、前記導電性焼結体からなる第２の接続膜を介して前記第１の受光面電極に電気的に接続されている場合にも効果的である。
　一方、本発明は、光入射側の表面側に第１導電型層を有し、かつ、裏面側に第２導電型層を有する半導体基板の第１導電型層上に、反射防止膜が設けられた太陽電池用基板を用意し、ガラスフリットを含有する導電性ペーストを用い、当該導電性ペーストを焼結させることにより、導体からなるボンディングワイヤによって構成された受光面電極を前記太陽電池用基板上に固着するとともに、当該受光面電極を前記半導体基板の第１導電型層に対して電気的に接続させる工程を有する結晶系太陽電池セルの製造方法である。
　本発明では、前記受光面電極が、第１及び第２の受光面電極を備え、前記反射防止膜上に前記導電性ペーストを塗布乾燥して第１の接続膜を形成する工程と、前記第１の接続膜上に前記第１の受光面電極を配置する工程と、前記第１の接続膜を焼結させる工程と、前記第１の受光面電極上に前記導電性ペーストを塗布乾燥して第２の接続膜を形成する工程と、前記第２の接続膜を焼結させる工程とを有する場合にも効果的である。
　本発明では、前記ボンディングワイヤに前記導電性ペーストを塗布乾燥して接続膜を形成した受光面電極を用意し、前記受光面電極を前記太陽電池用基板上に配置する工程と、前記受光面電極の接続膜を焼結させる工程とを有する場合にも効果的である。
　本発明では、前記導電性ペーストを塗布する工程が、ディスペンサ法又はインクジェット法によるものである場合にも効果的である。 The present invention made in order to solve the above-mentioned problems comprises a semiconductor substrate having a first conductivity type layer on the light incident side surface side and a second conductivity type layer on the back surface side, An antireflection film and a light receiving surface electrode are provided on the first conductive type layer, and a back electrode for connection is provided on the second conductive type layer of the semiconductor substrate, and the light receiving surface electrode is made of a conductor. It is a crystalline solar cell constituted by bonding wires.
The present invention is also effective when the bonding wire is made of gold, silver, copper, aluminum, palladium, or an alloy thereof.
The present invention is also effective when the light-receiving surface electrode is electrically connected to the first conductivity type layer of the semiconductor substrate via a connection film made of a conductive sintered body containing glass frit. is there.
In the present invention, the light receiving surface electrode includes a first light receiving surface electrode provided on the first conductivity type layer of the semiconductor substrate, and a second light receiving surface electrode provided on the first light receiving surface electrode. And the first light-receiving surface electrode is electrically connected to the first conductivity type layer of the semiconductor substrate through a first connection film made of the conductive sintered body, and It is also effective when the second light receiving surface electrode is electrically connected to the first light receiving surface electrode via the second connection film made of the conductive sintered body.
On the other hand, in the present invention, an antireflection film is provided on the first conductive type layer of the semiconductor substrate having the first conductive type layer on the light incident side surface side and the second conductive type layer on the back side. Prepared a solar cell substrate, and using a conductive paste containing glass frit and sintering the conductive paste, the light-receiving surface electrode composed of a bonding wire made of a conductor is used as the solar cell substrate. It is a method for manufacturing a crystalline solar battery cell having a step of fixing the light receiving surface electrode to the first conductivity type layer of the semiconductor substrate while being fixed to the top.
In the present invention, the light receiving surface electrode includes first and second light receiving surface electrodes, and a step of applying and drying the conductive paste on the antireflection film to form a first connection film; Disposing the first light-receiving surface electrode on the first connection film; sintering the first connection film; and applying and drying the conductive paste on the first light-receiving surface electrode. It is also effective in the case of having a step of forming the second connection film and a step of sintering the second connection film.
In the present invention, a light receiving surface electrode in which a conductive film is applied to the bonding wire and dried to form a connection film is prepared, and the light receiving surface electrode is disposed on the solar cell substrate; It is also effective when it has the process of sintering this connection film | membrane.
In the present invention, the process of applying the conductive paste is also effective when the dispenser method or the ink jet method is used.
　本発明の場合、受光面電極が導体からなるボンディングワイヤによって構成されており、従来技術のスクリーン印刷による受光面電極と比較して、同等の配線抵抗を有する電極を作成する場合に、受光面電極の幅を非常に小さくすることができる。その結果、従来技術では９３％程度であった太陽電池セルの開口率を、９９％程度と大幅に向上させることができる。 In the case of the present invention, the light-receiving surface electrode is constituted by a bonding wire made of a conductor, and the light-receiving surface electrode is formed when an electrode having an equivalent wiring resistance is formed as compared with the light-receiving surface electrode by screen printing of the prior art The width of can be made very small. As a result, the aperture ratio of the solar cells, which was about 93% in the prior art, can be significantly improved to about 99%.
　また、本発明の場合、導電性ペーストの塗布及び焼結によって受光面電極を太陽電池用基板上に固着することから、導電性ペーストの塗布手段が太陽電池用基板に接触することがなく、従来のスクリーン印刷の場合のように基板が割れたり、シリコン層にダメージを与えることがない。 In the case of the present invention, since the light-receiving surface electrode is fixed onto the solar cell substrate by applying and sintering the conductive paste, the conductive paste coating means does not come into contact with the solar cell substrate. As is the case with screen printing, the substrate is not broken and the silicon layer is not damaged.
　さらに、本発明においては、ボンディングワイヤからなる受光面電極を導電性ペーストを介して反射防止膜上に配置し、その状態で、ガラスフリットを含有する導電性ペーストからなる第１の接続膜を焼結させることから、反射防止膜と第１の接続膜の反応によるファイアースルーにより、焼結された接続膜を介して受光面電極と半導体基板の第１導電型層とを確実に電気的に接続することができる。 Furthermore, in the present invention, the light-receiving surface electrode made of a bonding wire is disposed on the antireflection film via the conductive paste, and in this state, the first connection film made of the conductive paste containing glass frit is baked. As a result, the light-receiving surface electrode and the first conductive type layer of the semiconductor substrate are reliably electrically connected through the sintered connection film by fire-through due to the reaction between the antireflection film and the first connection film. can do.
　本発明によれば、結晶系太陽電池セルの開口率を大幅に向上させることができる。 According to the present invention, the aperture ratio of the crystalline solar cell can be greatly improved.
（ａ）～（ｄ）：本実施の形態の結晶系太陽電池セルの製造工程を示す断面図（その１）(A)-(d): Sectional drawing which shows the manufacturing process of the crystalline solar cell of this Embodiment (the 1) （ａ）～（ｃ）：同実施の形態の結晶系太陽電池セルの製造工程を示す断面図（その２）(A)-(c): Sectional drawing which shows the manufacturing process of the crystalline solar cell of the embodiment (the 2) 同実施の形態の結晶系太陽電池セルの平面図Plan view of the crystalline solar battery cell of the same embodiment （ａ）～（ｃ）：本発明の他の実施の形態を示す断面図(A) to (c): Sectional views showing other embodiments of the present invention （ａ）：従来の結晶系太陽電池のセル構造を示す概略図　　　（ｂ）：従来の結晶系太陽電池のセル構造を示す平面図(A): Schematic diagram showing the cell structure of a conventional crystalline solar cell (b): Plan view showing the cell structure of a conventional crystalline solar cell
１…太陽電池用基板、１０…シリコン基板（半導体基板）、１１…ｎ+型半導体層（第１導電型層）、１２…反射防止膜、１３…ｐ+型半導体層（第２導電型層）、１４…裏面電極層、１５…第１の接続膜、１６…第１の焼結接続膜、１７…第２の接続膜、１８…第２の焼結接続膜、２１…フィンガー電極（第１の受光面電極）、２２…バスバー電極（第２の受光面電極）、３０…結晶系太陽電池セル DESCRIPTION OF SYMBOLS 1 ... Substrate for solar cells, 10 ... Silicon substrate (semiconductor substrate), 11 ... n <+> type semiconductor layer (first conductivity type layer), 12 ... Antireflection film, 13 ... p + type semiconductor layer (second conductivity type layer) ), 14 ... Back electrode layer, 15 ... First connection film, 16 ... First sintered connection film, 17 ... Second connection film, 18 ... Second sintered connection film, 21 ... Finger electrode (first electrode) 1 light-receiving surface electrode), 22 ... bus bar electrode (second light-receiving surface electrode), 30 ... crystalline solar cell
　以下、本発明の好ましい実施の形態を図面を参照して詳細に説明する。
　図１（ａ）～（ｄ）は、本実施の形態の結晶系太陽電池セルの製造工程を示す断面図（その１）、図２（ａ）～（ｃ）は、同実施の形態の結晶系太陽電池セルの製造工程を示す断面図（その２）である。また、図３は、同実施の形態の結晶系太陽電池セルの平面図である。
　図１（ａ）に示すように、本実施の形態においては、まず、テクスチャー（図示せず）が形成されたシリコン基板（半導体基板）１０の表側面（光が入射する側の面）に、第１導電型層であるｎ+型半導体層１１、反射防止膜１２が順次形成され、その裏側面に、第２導電型層であるｐ+型半導体層１３、裏面電極層１４が順次形成された太陽電池用基板１を用意する。
　本発明の場合、反射防止膜１２の材料は、特に限定されることはないが、後述する焼結時の導電性ペーストとの反応性を確保する観点からは、窒化珪素（ＳｉＮ）、酸化珪素（ＳｉＯ2）、酸化チタン（ＴｉＯ2）を好適に用いることができる。
　また、反射防止膜１２の厚さは、特に限定されることはないが、反射率を低減させる観点からは、１００～５００ｎｍとすることが好ましい。
　なお、裏面電極層１４の材料としては、例えば、銀（Ａｇ）ペーストを好適に用いることができる。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
1 (a) to 1 (d) are cross-sectional views (part 1) showing the manufacturing process of the crystalline solar cell according to the present embodiment, and FIGS. 2 (a) to (c) are the crystals of the same embodiment. It is sectional drawing (the 2) which shows the manufacturing process of a solar cell. FIG. 3 is a plan view of the crystalline solar battery cell of the same embodiment.
As shown in FIG. 1A, in the present embodiment, first, on the front side surface (surface on which light is incident) of a silicon substrate (semiconductor substrate) 10 on which a texture (not shown) is formed, An n + type semiconductor layer 11 that is a first conductivity type layer and an antireflection film 12 are sequentially formed, and a p + type semiconductor layer 13 that is a second conductivity type layer and a back electrode layer 14 are sequentially formed on the back side thereof. A solar cell substrate 1 is prepared.
In the case of the present invention, the material of the antireflection film 12 is not particularly limited, but from the viewpoint of ensuring the reactivity with the conductive paste during sintering described later, silicon nitride (SiN), silicon oxide (SiO 2 ) and titanium oxide (TiO 2 ) can be preferably used.
Further, the thickness of the antireflection film 12 is not particularly limited, but is preferably 100 to 500 nm from the viewpoint of reducing the reflectance.
In addition, as a material of the back electrode layer 14, for example, a silver (Ag) paste can be suitably used.
　次に、図１（ｂ）に示すように、反射防止膜１２の表面に、所定の間隔をおいて、後述の導電性ペーストからなる複数の第１の接続膜（接続膜）１５を塗布形成し、その後、これら第１の接続膜１５を乾燥させる。
　ここで、第１の接続膜１５を塗布形成する位置は、後述するフィンガー電極（第１の受光面電極）２１を設ける位置に対応する位置であり、例えば、フィンガー電極２１の長さと同等の長さに塗布形成するとよい。
　本発明の場合、第１の接続膜１５の塗布方法は、特に限定されることはないが、精度良く第１の接続膜１５を形成する観点からは、ディスペンサによる方法やインクジェットによる方法を採用することが好ましい。
　また、第１の接続膜１５の幅は、特に限定されることはないが、太陽電池セルの開口率を一層向上させる観点からは、フィンガー電極２１の幅より第１の接続膜１５の幅を小さくすることが好ましい。
　具体的には、第１の接続膜１５の幅を、５～１５μｍに設定することが好ましい。 Next, as shown in FIG. 1B, a plurality of first connection films (connection films) 15 made of a conductive paste described later are applied and formed on the surface of the antireflection film 12 at a predetermined interval. Thereafter, the first connection film 15 is dried.
Here, the position where the first connection film 15 is formed by coating is a position corresponding to a position where a finger electrode (first light-receiving surface electrode) 21 described later is provided, for example, a length equivalent to the length of the finger electrode 21. Furthermore, it is good to apply and form.
In the present invention, the method for applying the first connection film 15 is not particularly limited, but from the viewpoint of forming the first connection film 15 with high accuracy, a method using a dispenser or a method using an ink jet is employed. It is preferable.
Further, the width of the first connection film 15 is not particularly limited, but from the viewpoint of further improving the aperture ratio of the solar battery cell, the width of the first connection film 15 is set to be larger than the width of the finger electrode 21. It is preferable to make it small.
Specifically, the width of the first connection film 15 is preferably set to 5 to 15 μm.
　一方、第１の接続膜１５の厚さは、特に限定されることはないが、十分な接着強度を確保し、かつ、太陽電池セルの開口率を一層向上させる観点からは、反射防止膜１２より厚くすることが好ましい。
　具体的には、第１の接続膜１５の厚さを、５００～１００００ｎｍに設定することが好ましい。
　第１の接続膜１５に用いる導電性ペーストとしては、例えば、特開２００６－２９５１９７号公報に記載された導電性ペーストを好適に用いることができる。 On the other hand, the thickness of the first connection film 15 is not particularly limited, but from the viewpoint of securing sufficient adhesive strength and further improving the aperture ratio of the solar battery cell, the antireflection film 12 is provided. It is preferable to make it thicker.
Specifically, it is preferable to set the thickness of the first connection film 15 to 500 to 10,000 nm.
As the conductive paste used for the first connection film 15, for example, a conductive paste described in JP-A-2006-295197 can be suitably used.
　本発明で使用する導電性ペーストは、導電性金属と、無機結合剤と、有機ビヒクルとを含有する。以下、それぞれの成分毎に説明する。
　本発明に用いる導電性ペーストにおいて含有可能な導電性金属としては、銀粒子を挙げることができ、かつ、銀粒子が最も好ましい。この銀粒子は、好ましくはフレーク形態または粉末形態のものである。
　本発明の場合、導電性ペーストの銀粒子の粒径は、特に限定されることはないが、焼結特性の影響（大きな粒径を有する銀粒子は、小さい粒径を有する銀粒子の速度よりも遅い速度で焼結すること）及び塗布のし易さを考慮すると、銀粒子の平均粒径は、３．０～１５．０μｍとすることが好ましく、より好ましくは５．０～１１．０μｍ である。
　銀粒子の粒径が３．０μ ｍより小さい場合、銀導電性ペーストは急峻な焼結挙動を示し、アルミニウムペーストとの焼結速度の不整合に起因して、それら２つの電極間で亀裂が発生する傾向がある。
　他方、銀粒子の粒径が１５．０μｍより大きい場合、導電性が低下し、および電極フィルムの強度が減少する。この理由は、焼結が十分に進行しないからである。
　導電性ペーストに含まれる銀粒子としては、銀が高い純度（９９％以上）を有することが好ましいが、電極パターンの電気的要請に応じて、９９％未満の純度を有する物質もまた用いることができる。 The conductive paste used in the present invention contains a conductive metal, an inorganic binder, and an organic vehicle. Hereinafter, each component will be described.
Examples of the conductive metal that can be contained in the conductive paste used in the present invention include silver particles, and silver particles are most preferable. The silver particles are preferably in flake form or powder form.
In the case of the present invention, the particle size of the silver particles of the conductive paste is not particularly limited. However, the influence of the sintering characteristics (silver particles having a large particle size is larger than the speed of silver particles having a small particle size). Sintering at a slower speed) and ease of application, the average particle size of the silver particles is preferably 3.0-15.0 μm, more preferably 5.0-11.0 μm. It is.
When the particle size of the silver particles is smaller than 3.0 μm, the silver conductive paste exhibits a steep sintering behavior, and cracks between the two electrodes are caused by the mismatch of the sintering rate with the aluminum paste. Tend to occur.
On the other hand, when the particle size of the silver particles is larger than 15.0 μm, the conductivity is lowered and the strength of the electrode film is reduced. This is because sintering does not proceed sufficiently.
As silver particles contained in the conductive paste, it is preferable that silver has a high purity (99% or more), but a substance having a purity of less than 99% may also be used according to the electrical requirements of the electrode pattern. it can.
　導電性ペーストにおける最も好ましい導電性金属は、上述したように、銀粒子であるが、銀以外の導電性金属を同様に用いることができる。例えば、銅（Ｃｕ）、金（Ａｕ）、パラジウム（Ｐｄ）および白金（Ｐｔ）のような金属は有用である。加えて、前述の金属の合金または混合物も、本発明において同様に有用である。例えば、Ｃｕ－Ａｕ、Ａｇ－Ｐｄ、Ｐｔ－Ａｕなどを用いることができる。
　導電性ペーストにおける導電性金属の含有量は、本発明の目的を達成することができる量である限り、特に限定されることはないが、導電性確保の観点からは、例えば銀粒子について、導電性ペーストの重量を基準として４０～９３質量％の量で含有させることが好ましい。
　なお、所望の特性を向上させる目的で、導電性ペーストに対してアルミニウム（Ａｌ）を添加することもできる。 As described above, the most preferable conductive metal in the conductive paste is silver particles, but conductive metals other than silver can be used similarly. For example, metals such as copper (Cu), gold (Au), palladium (Pd) and platinum (Pt) are useful. In addition, alloys or mixtures of the aforementioned metals are useful in the present invention as well. For example, Cu—Au, Ag—Pd, Pt—Au, or the like can be used.
The content of the conductive metal in the conductive paste is not particularly limited as long as it is an amount that can achieve the object of the present invention. From the viewpoint of ensuring conductivity, It is preferably contained in an amount of 40 to 93% by mass based on the weight of the conductive paste.
Note that aluminum (Al) can be added to the conductive paste for the purpose of improving desired characteristics.
　本発明に用いる導電性ペーストは、無機結合剤を含む。
　このような無機結合剤としては、４５０～５５０℃の軟化点を有するガラスフリット（微粒子）を好適に用いることができる。
　このようなガラスフリットは、導電性ペーストを６００～８００℃でベークし、適切に焼結および湿潤し、およびシリコン基板１０に対して適切に接着させることができる。
　ガラスフリットの軟化点が４５０℃より低いと、焼結が過剰となり、本発明の効果を十分に得ることができない場合がある。
　他方、ガラスフリットの軟化点が５５０℃より高いと、充分な接着強さが発揮されず、かつ、銀の液相焼結を促進することができない場合がある。この理由は、焼結中に充分な溶融流れが発生しないことに起因する。
　本明細書では、軟化点として、ＡＳＴＭ（米国材料試験協会：American Society for Testing and Materials）　Ｃ３３８－５７の繊維伸長法（fiber elongation method）によって規定されるものを適用する。 The conductive paste used in the present invention contains an inorganic binder.
As such an inorganic binder, a glass frit (fine particles) having a softening point of 450 to 550 ° C. can be suitably used.
Such a glass frit can bake the conductive paste at 600 to 800 ° C., appropriately sinter and wet, and properly adhere to the silicon substrate 10.
When the softening point of the glass frit is lower than 450 ° C., sintering becomes excessive, and the effects of the present invention may not be sufficiently obtained.
On the other hand, if the softening point of the glass frit is higher than 550 ° C., sufficient adhesion strength may not be exhibited, and liquid phase sintering of silver may not be promoted. This is because a sufficient melt flow does not occur during sintering.
In this specification, the softening point is defined by ASTM (American Society for Testing and Materials) C338-57 fiber elongation method.
　導電性ペーストに含有されるガラスフリットとしては、特に限定されることはないが、軟化点範囲及びガラス可融性の両方の条件を考慮すると、例えば、ケイ酸ガラス、ホウケイ酸鉛ガラスなどを好適に用いることができる。
　なお、ホウケイ酸亜鉛のような鉛を含有しないガラスを用いることもできる。 The glass frit contained in the conductive paste is not particularly limited, but considering both the softening point range and the glass fusibility, for example, silicate glass, lead borosilicate glass, etc. are suitable. Can be used.
It is also possible to use glass that does not contain lead, such as zinc borosilicate.
　無機結合剤としてのガラスフリットの含有量は、本発明の目的を達成することができる量である限り、特に限定されることはないが、導電性ペーストの総重量を基準として２．０～１０．０質量％とすることが好ましく、より好ましくは３．０～６．０質量％である。
　ガラスフリットの含有量が２．０質量％よりも少ないと、接着強さが不充分となる場合があり、他方、ガラスフリットの量が１０．０質量％より多いと、例えば、後加工として行うハンダ付け工程が、ガラスの浮遊(glassfloating)などによって阻害される場合がある。 The content of the glass frit as the inorganic binder is not particularly limited as long as it can achieve the object of the present invention, but is 2.0 to 10 based on the total weight of the conductive paste. The content is preferably 0.0 mass%, more preferably 3.0 to 6.0 mass%.
If the glass frit content is less than 2.0% by mass, the adhesive strength may be insufficient. On the other hand, if the glass frit content is more than 10.0% by mass, for example, post-processing is performed. The soldering process may be hindered by glass floating or the like.
　本発明に用いる導電性ペーストは、有機ビヒクルを含む。
　導電性ペーストに含まれる有機ビヒクルとしては、不活性液体を使用することができる。
　このような不活性液体としては、有機液体として、例えば、アルコール類；アルコールのエステル類（アセテートまたはプロピオネートのようなもの）；デンプン（パイン油およびテルピネオールのようなもの）；樹脂（ポリメタクリレートなど）またはエチルセルロースのパイン油溶液またはエチレングリコールモノブチルエーテルモノアセテートの溶液、またはエチルセルロースのテルピネオール溶液のような種々の溶液を挙げることができる。 The conductive paste used in the present invention contains an organic vehicle.
An inert liquid can be used as the organic vehicle contained in the conductive paste.
Such inert liquids include organic liquids such as alcohols; alcohol esters (such as acetate or propionate); starch (such as pine oil and terpineol); resins (such as polymethacrylate). Alternatively, various solutions such as a pine oil solution of ethyl cellulose or a solution of ethylene glycol monobutyl ether monoacetate, or a terpineol solution of ethyl cellulose can be mentioned.
　本発明においては、有機ビヒクルとして、エチルセルロースのテルピネオール溶液（エチルセルロース含有量＝５～５０質量％）を好適に用いることができる。
　有機ビヒクルの好ましい含有量は、導電性ペーストの総重量を基準として５～５０質量％である。 In the present invention, a terpineol solution of ethyl cellulose (ethyl cellulose content = 5 to 50% by mass) can be suitably used as the organic vehicle.
A preferable content of the organic vehicle is 5 to 50% by mass based on the total weight of the conductive paste.
　本発明に用いる導電性ペーストには、増粘剤や安定剤、また他の一般的な添加剤を添加することができる。
　添加剤を用いる際に、粘着付与剤（剤粘剤）、安定剤などを添加することができるし、あるいは、他の一般的添加剤として分散剤、粘度調整剤などを添加することもできる。
　添加剤の量は、最終的に得られる導電性ペーストの特性に基づいて決定され、関与する製造者が適宜決定することができる。なお、数種の添加剤を使用することもできる。 A thickener, a stabilizer, and other general additives can be added to the conductive paste used in the present invention.
When using the additive, a tackifier (agent thickener), a stabilizer and the like can be added, or a dispersant, a viscosity modifier and the like can be added as other general additives.
The amount of the additive is determined based on the properties of the finally obtained conductive paste, and can be appropriately determined by the manufacturer involved. Several types of additives can also be used.
　本発明に用いる導電性ペーストは、所定の範囲内の粘度を有することが好ましい。
　導電性ペーストに対して適切な粘度を与えるためには、上述した粘着付与剤（増粘剤）を添加することで達成できる。
　本発明に用いる導電性ペーストは、上述した各成分を公知の３本ロールニーダーによって混合することによって製造することができる。
　本発明に用いる導電性ペーストの粘度は、特に限定されることはないが、ブルックフィールド(Brookfield)ＨＢＴ粘度計および＃１４スピンドルを用いるユーティリティカップを用い、回転数１０ｒｐｍおよび温度２５℃において測定される際に、５０～３００Ｐａ・Ｓとなるように調整することが好ましい。 The conductive paste used in the present invention preferably has a viscosity within a predetermined range.
In order to give an appropriate viscosity to the conductive paste, it can be achieved by adding the above-described tackifier (thickener).
The electrically conductive paste used for this invention can be manufactured by mixing each component mentioned above with a well-known 3 roll kneader.
The viscosity of the conductive paste used in the present invention is not particularly limited, but is measured at a rotation speed of 10 rpm and a temperature of 25 ° C. using a Brookfield HBT viscometer and a utility cup using a # 14 spindle. At this time, it is preferable to adjust the pressure to 50 to 300 Pa · S.
　本実施の形態においては、以上説明した導電性ペーストからなる第１の接続膜１５を、反射防止膜１２上に複数塗布形成した後、これらの第１の接続膜１５を乾燥させる。この場合、好ましい乾燥温度は、１８０℃以下である。
　さらに、図１（ｃ）に示すように、第１の接続膜１５のそれぞれの上に、ボンディングワイヤからなるフィンガー電極２１を位置合わせして配置（載置）する。
　本発明の場合、フィンガー電極２１を構成するボンディングワイヤの材料は、特に限定されることはないが、金（Ａｕ）、銀（Ａｇ）、銅（Ｃｕ）、アルミニウム（Ａｌ）、パラジウム（Ｐｄ）、又はこれらの合金からなるものを好適に用いることができる。
　これらのうちでも、導電性を向上させる観点からは、銀（Ａｇ）を用いることが好ましい。
　なお、フィンガー電極２１を構成するボンディングワイヤの断面形状は真円形状であり、開口率を向上させる観点からは、その直径は、小さい程好ましい。
　ただし、電極として要求される強度や配線抵抗の大きさを考慮すると、直径が１０～１００μｍとすることが好ましい。 In the present embodiment, a plurality of first connection films 15 made of the conductive paste described above are applied and formed on the antireflection film 12, and then the first connection films 15 are dried. In this case, a preferable drying temperature is 180 ° C. or less.
Further, as shown in FIG. 1C, finger electrodes 21 made of bonding wires are aligned and placed (placed) on each of the first connection films 15.
In the present invention, the material of the bonding wire constituting the finger electrode 21 is not particularly limited, but gold (Au), silver (Ag), copper (Cu), aluminum (Al), palladium (Pd) Or those made of these alloys can be suitably used.
Among these, it is preferable to use silver (Ag) from the viewpoint of improving conductivity.
In addition, the cross-sectional shape of the bonding wire which comprises the finger electrode 21 is a perfect circle shape, and it is so preferable that the diameter is small from a viewpoint of improving an aperture ratio.
However, considering the strength required for the electrode and the size of the wiring resistance, the diameter is preferably 10 to 100 μm.
　さらに、フィンガー電極２１を配置した太陽電池用基板１を、空気中で、温度６００～８００℃、２～１５分にわたって加熱して焼結させる。この場合、フィンガー電極２１を加圧してもよい。
　これにより、第１の接続膜１５の導電性ペーストに含まれるガラスフリットと反射防止膜１２の物質が反応し、反射防止膜１２が融解して、図１（ｄ）に示すように、焼結した第１の接続膜（以下「第１の焼結接続膜」という。）１６が反射防止膜１２中に埋没する（ファイアスルー）。 Further, the solar cell substrate 1 on which the finger electrodes 21 are arranged is heated and sintered in the air at a temperature of 600 to 800 ° C. for 2 to 15 minutes. In this case, the finger electrode 21 may be pressurized.
As a result, the glass frit contained in the conductive paste of the first connection film 15 reacts with the substance of the antireflection film 12, and the antireflection film 12 melts, as shown in FIG. The first connection film 16 (hereinafter referred to as “first sintered connection film”) 16 is buried in the antireflection film 12 (fire-through).
　さらに、上述した焼結工程によって、各フィンガー電極２１が、第１の焼結接続膜１６に対して固着される。
　その結果、第１の焼結接続膜１６とｎ+型半導体層１１が接触してこれらが電気的に接続されるので、接続膜である第１の焼結接続膜１６を介してフィンガー電極２１とｎ+型半導体層１１とが電気的に接続される。 Furthermore, each finger electrode 21 is fixed to the first sintered connection film 16 by the above-described sintering step.
As a result, the first sintered connection film 16 and the n + -type semiconductor layer 11 come into contact with each other and are electrically connected to each other, so that the finger electrode 21 passes through the first sintered connection film 16 that is a connection film. And n + type semiconductor layer 11 are electrically connected.
　この状態においては、第１の焼結接続膜１６の幅は、各フィンガー電極２１の幅より小さい。
　なお、上述した焼結工程により、裏面電極層１４の銀ペーストも焼成され、焼結裏面電極層１４ａが形成される。 In this state, the width of the first sintered connection film 16 is smaller than the width of each finger electrode 21.
In addition, the silver paste of the back surface electrode layer 14 is also baked by the sintering process described above, and the sintered back surface electrode layer 14a is formed.
　その後、図２（ａ）に示すように、上述した導電性ペーストからなる第２の接続膜１７を、各フィンガー電極２１上に塗布形成し、その後、これらを乾燥させる。
　本発明の場合、第２の接続膜１７の塗布方法は、特に限定されることはないが、精度良く第２の接続膜１７を形成する観点からは、ディスペンサによる方法やインクジェットによる方法を採用することが好ましい。
　また、第２の接続膜１７の幅は、特に限定されることはないが、太陽電池セルの開口率を一層向上させる観点からは、後述するバスバー電極２２の幅より第２の接続膜１７の長さ（バスバー電極２２の延びる方向に対して直交する方向の長さ）を小さくすることが好ましい。
　具体的には、第２の接続膜１７の幅を、５～１５μｍに設定することが好ましい。
　なお、第２の接続膜１７の好ましい乾燥温度は、１８０℃以下である。
　一方、第１の接続膜１５の厚さは、５００～１００００ｎｍに設定することが好ましい。 Thereafter, as shown in FIG. 2A, the second connection film 17 made of the above-described conductive paste is applied and formed on each finger electrode 21, and then these are dried.
In the case of the present invention, the method for applying the second connection film 17 is not particularly limited, but from the viewpoint of forming the second connection film 17 with high accuracy, a method using a dispenser or a method using an ink jet is employed. It is preferable.
Further, the width of the second connection film 17 is not particularly limited, but from the viewpoint of further improving the aperture ratio of the solar battery cell, the width of the second connection film 17 is larger than the width of the bus bar electrode 22 described later. It is preferable to reduce the length (the length in the direction orthogonal to the direction in which the bus bar electrode 22 extends).
Specifically, the width of the second connection film 17 is preferably set to 5 to 15 μm.
A preferable drying temperature of the second connection film 17 is 180 ° C. or lower.
On the other hand, the thickness of the first connection film 15 is preferably set to 500 to 10,000 nm.
　さらに、図２（ｂ）に示すように、第２の接続膜１７のそれぞれの上に、ボンディングワイヤからなるバスバー電極２２を位置合わせして配置（載置）する。
　本発明の場合、バスバー電極２２を構成するボンディングワイヤの材料は、特に限定されることはないが、金（Ａｕ）、銀（Ａｇ）、銅（Ｃｕ）、アルミニウム（Ａｌ）、パラジウム（Ｐｄ）、又はこれらの合金からなるものを好適に用いることができる。
　これらのうちでも、導電性を向上させる観点からは、銀（Ａｇ）を用いることが好ましい。
　なお、バスバー電極２２を構成するボンディングワイヤの断面形状は真円形状であり、太陽電池セルの開口率を向上させる観点からは、その直径は、小さい程好ましい。
　ただし、電極として要求される強度や配線抵抗の大きさを考慮すると、直径が１２０～５００μｍ以下とすることが好ましい。 Further, as shown in FIG. 2B, the bus bar electrodes 22 made of bonding wires are aligned and placed (placed) on each of the second connection films 17.
In the present invention, the material of the bonding wire constituting the bus bar electrode 22 is not particularly limited, but gold (Au), silver (Ag), copper (Cu), aluminum (Al), palladium (Pd) Or those made of these alloys can be suitably used.
Among these, it is preferable to use silver (Ag) from the viewpoint of improving conductivity.
In addition, the cross-sectional shape of the bonding wire which comprises the bus-bar electrode 22 is a perfect circle shape, From the viewpoint of improving the aperture ratio of a photovoltaic cell, the diameter is so preferable that it is small.
However, considering the strength required for the electrode and the size of the wiring resistance, the diameter is preferably 120 to 500 μm or less.
　さらに、バスバー電極２２を配置した太陽電池用基板１を、空気中で、温度６００～８００℃、２～１５分にわたって加熱して焼結させる。この場合、バスバー電極２２を加圧してもよい。
　これにより、第２の接続膜１７が焼結され、各フィンガー電極２１が、焼結された第２の接続膜（以下「第２の焼結接続膜」という。）１８に対して固着されるとともに、各バスバー電極２２が、第２の焼結接続膜１８に対して固着される。
　その結果、図２（ｃ）及び図３に示すように、接続膜である第２の焼結接続膜１８を介してバスバー電極２２とフィンガー電極２１とが電気的に接続され、シリコン基板１０に対して電気的に接続された第１及び第２の受光面電極を有する結晶系太陽電池セル３０を得る。 Further, the solar cell substrate 1 on which the bus bar electrodes 22 are arranged is heated and sintered in air at a temperature of 600 to 800 ° C. for 2 to 15 minutes. In this case, the bus bar electrode 22 may be pressurized.
As a result, the second connection film 17 is sintered, and each finger electrode 21 is fixed to the sintered second connection film 18 (hereinafter referred to as “second sintered connection film”). At the same time, each bus bar electrode 22 is fixed to the second sintered connection film 18.
As a result, as shown in FIG. 2C and FIG. 3, the bus bar electrode 22 and the finger electrode 21 are electrically connected via the second sintered connection film 18 which is a connection film, and the silicon substrate 10 is connected. A crystalline solar cell 30 having first and second light-receiving surface electrodes that are electrically connected to each other is obtained.
　以上述べたように本実施の形態においては、受光面電極であるフィンガー電極２１及びバスバー電極２２が、導体からなるボンディングワイヤによって構成されており、従来技術のスクリーン印刷による受光面電極と比較して、同等の配線抵抗を有する電極を作成する場合に、受光面電極の幅を非常に小さくすることができる。その結果、結晶系太陽電池セルの開口率を大幅に向上させることができる。 As described above, in the present embodiment, the finger electrode 21 and the bus bar electrode 22 that are light receiving surface electrodes are configured by bonding wires made of conductors, compared with the light receiving surface electrodes by screen printing of the prior art. When an electrode having an equivalent wiring resistance is created, the width of the light receiving surface electrode can be made very small. As a result, the aperture ratio of the crystalline solar battery cell can be greatly improved.
　また、本実施の形態においては、導電性ペーストの塗布乾燥及び焼結によってフィンガー電極２１及びバスバー電極２２を太陽電池用基板１上に固着することから、導電性ペーストの塗布手段が太陽電池用基板１に接触することがなく、従来のスクリーン印刷の場合のように基板が割れたり、シリコン層にダメージを与えることがない。 In the present embodiment, since the finger electrodes 21 and the bus bar electrodes 22 are fixed onto the solar cell substrate 1 by applying and drying and sintering the conductive paste, the means for applying the conductive paste is the solar cell substrate. 1 is not touched, and the substrate is not broken and the silicon layer is not damaged as in the case of conventional screen printing.
　また、本実施の形態においては、ボンディングワイヤからなるフィンガー電極２１を導電性ペーストを介して反射防止膜１２上に配置し、その状態で、ガラスフリットを含有する導電性ペーストからなる第１の接続膜１５を焼結させることから、反射防止膜１２と第１の接続膜１５の反応によるファイアースルーにより、第１の焼結接続膜１６を介してフィンガー電極２１と半導体基板１０のｎ+型半導体層１１とを確実に電気的に接続することができる。 In the present embodiment, the finger electrode 21 made of a bonding wire is disposed on the antireflection film 12 via a conductive paste, and in this state, the first connection made of a conductive paste containing glass frit is used. Since the film 15 is sintered, the finger electrode 21 and the n + type semiconductor of the semiconductor substrate 10 are interposed through the first sintered connection film 16 by fire-through due to the reaction between the antireflection film 12 and the first connection film 15. The layer 11 can be reliably electrically connected.
　図４（ａ）～（ｃ）は、本発明の他の実施の形態を示すものであり、以下、上記実施の形態と共通する部分には同一の符号を付しその詳細な説明を省略する。
　本実施の形態においては、まず、図１（ａ）～（ｄ）を参照して説明したように、導電性ペーストの塗布、乾燥及び焼結を行うことにより、太陽電池用基板１上において、第１の焼結接続膜１６を介してフィンガー電極２１とｎ+型半導体層１１とを電気的に接続する。
　その後、図４（ａ）に示すように、バスバー電極２２の表面に、所定の間隔をおいて、上記導電性ペーストからなる複数の第２の接続膜１７を塗布形成し、その後、これらを乾燥させる。
　ここで、バスバー電極２２表面の第２の接続膜１７を塗布形成する位置は、太陽電池用基板１上に設けられたフィンガー電極２１との接続部分とすることが好ましい。 4 (a) to 4 (c) show other embodiments of the present invention. In the following, the same reference numerals are given to the portions common to the above-described embodiments, and the detailed description thereof will be omitted. .
In the present embodiment, first, as described with reference to FIGS. 1 (a) to (d), the conductive paste is applied, dried and sintered, so that on the solar cell substrate 1, The finger electrode 21 and the n + type semiconductor layer 11 are electrically connected through the first sintered connection film 16.
Thereafter, as shown in FIG. 4A, a plurality of second connection films 17 made of the conductive paste are applied and formed on the surface of the bus bar electrode 22 at a predetermined interval, and then dried. Let
Here, the position where the second connection film 17 on the surface of the bus bar electrode 22 is formed by application is preferably a connection portion with the finger electrode 21 provided on the solar cell substrate 1.
　本発明の場合、第２の接続膜１７の塗布方法は、特に限定されることはないが、バスバー電極２２表面に精度良く第２の接続膜１７を形成する観点からは、ディスペンサによる方法やインクジェットによる方法を採用することが好ましい。
　また、第２の接続膜１７の幅は、特に限定されることはないが、太陽電池セルの開口率を一層向上させる観点からは、バスバー電極２２の幅より第２の接続膜１７の長さ（バスバー電極２２の延びる方向に対して直交する方向の長さ）を小さくすることが好ましい。
　一方、第２の接続膜１７の厚さは、特に限定されることはないが、十分な接着強度を確保し、かつ、太陽電池セルの開口率を一層向上させる観点からは、５００～１００００ｎｍに設定することが好ましい。 In the case of the present invention, the method of applying the second connection film 17 is not particularly limited, but from the viewpoint of forming the second connection film 17 on the surface of the bus bar electrode 22 with high accuracy, a method using a dispenser or inkjet It is preferable to adopt the method according to
Further, the width of the second connection film 17 is not particularly limited, but from the viewpoint of further improving the aperture ratio of the solar battery cell, the length of the second connection film 17 is larger than the width of the bus bar electrode 22. It is preferable to reduce (the length in the direction orthogonal to the direction in which the bus bar electrode 22 extends).
On the other hand, the thickness of the second connection film 17 is not particularly limited, but it is 500 to 10,000 nm from the viewpoint of securing sufficient adhesive strength and further improving the aperture ratio of the solar battery cell. It is preferable to set.
　そして、バスバー電極２２の第２の接続膜１７と、太陽電池用基板１のフィンガー電極２１との位置が一致するように位置合わせを行い、図４（ｂ）に示すように、太陽電池用基板１上のフィンガー電極２１と第２の接続膜１７が接触するようにバスバー電極２２を配置（載置）する。
　その後、この太陽電池用基板１を、空気中で、温度６００～８００℃、２～１５分にわたって加熱して焼結させる。この場合、バスバー電極２２を加圧してもよい。
　これにより、上記実施の形態と同様に、第２の接続膜１７が焼結され、図４（ｃ）に示すように、各フィンガー電極２１が、第２の焼結接続膜１８に対して固着されるとともに、各バスバー電極２２が、第２の焼結接続膜１８に対して固着される。
　その結果、上記実施の形態と同様、第２の焼結接続膜１８を介してバスバー電極２２とフィンガー電極２１とが電気的に接続され、シリコン基板１０に対して電気的に接続された第１及び第２の受光面電極を有する結晶系太陽電池セル３０を得る。 And it aligns so that the position of the 2nd connection film 17 of the bus-bar electrode 22 and the finger electrode 21 of the board | substrate 1 for solar cells may correspond, and as shown in FIG.4 (b), the board | substrate for solar cells The bus bar electrode 22 is arranged (placed) so that the finger electrode 21 on the first layer and the second connection film 17 are in contact with each other.
Thereafter, the solar cell substrate 1 is heated and sintered in air at a temperature of 600 to 800 ° C. for 2 to 15 minutes. In this case, the bus bar electrode 22 may be pressurized.
As a result, as in the above embodiment, the second connection film 17 is sintered, and each finger electrode 21 is fixed to the second sintered connection film 18 as shown in FIG. In addition, each bus bar electrode 22 is fixed to the second sintered connection film 18.
As a result, the bus bar electrode 22 and the finger electrode 21 are electrically connected via the second sintered connection film 18 and electrically connected to the silicon substrate 10 as in the above embodiment. And the crystalline solar cell 30 which has a 2nd light-receiving surface electrode is obtained.
　以上述べた本実施の形態によれば、上記実施の形態と同様の効果に加えて、直列抵抗を低減することができるという効果がある。その他の構成及び作用効果については上述の実施の形態と同一であるのでその詳細な説明を省略する。 According to the present embodiment described above, in addition to the same effect as the above embodiment, there is an effect that the series resistance can be reduced. Since other configurations and operational effects are the same as those of the above-described embodiment, detailed description thereof is omitted.
　なお、本発明は上述の実施の形態に限られることなく、種々の変更を行うことができる。
　例えば、図４（ａ）～（ｃ）に示す実施の形態においては、バスバー電極２２に対して導電性ペーストを塗布して第２の接続膜１７を形成するようにしたが、本発明はこれに限られず、フィンガー電極２１に対して導電性ペーストを塗布して第１の接続膜１５を形成して焼結することもできる。
　また、例えば、フィンガー電極２１、バスバー電極２２を導電性ペーストに浸すことにより、フィンガー電極２１、バスバー電極２２の表面全面にそれぞれ接続膜を形成することもできる。
　さらに、本発明に用いる半導体基板は、単結晶シリコン基板、多結晶シリコン基板のいずれも用いることができる。  The present invention is not limited to the above-described embodiment, and various changes can be made.
For example, in the embodiment shown in FIGS. 4A to 4C, the second connection film 17 is formed by applying a conductive paste to the bus bar electrode 22, but the present invention is not limited to this. However, the first connecting film 15 can be formed by applying a conductive paste to the finger electrode 21 and sintered.
Further, for example, by immersing the finger electrode 21 and the bus bar electrode 22 in a conductive paste, a connection film can be formed on the entire surface of the finger electrode 21 and the bus bar electrode 22, respectively.
Furthermore, as the semiconductor substrate used in the present invention, either a single crystal silicon substrate or a polycrystalline silicon substrate can be used.

Claims (8)

  1. 　光入射側の表面側に第１導電型層を有し、かつ、裏面側に第２導電型層を有する半導体基板を備え、
    　前記半導体基板の第１導電型層上に、反射防止膜と、受光面電極とが設けられるとともに、前記半導体基板の第２導電型層上に接続用裏面電極が設けられ、
    　前記受光面電極が、導体からなるボンディングワイヤによって構成されている結晶系太陽電池セル。     A semiconductor substrate having a first conductivity type layer on the front side of the light incident side and a second conductivity type layer on the back side;
    An antireflection film and a light receiving surface electrode are provided on the first conductivity type layer of the semiconductor substrate, and a back electrode for connection is provided on the second conductivity type layer of the semiconductor substrate,
    A crystalline solar cell in which the light-receiving surface electrode is constituted by a bonding wire made of a conductor.
  2. 　前記ボンディングワイヤが、金、銀、銅、アルミニウム、パラジウム、又はこれらの合金からなる請求項１記載の結晶系太陽電池セル。 The crystalline solar cell according to claim 1, wherein the bonding wire is made of gold, silver, copper, aluminum, palladium, or an alloy thereof.
  3. 　前記受光面電極が、ガラスフリットを含有する導電性焼結体からなる接続膜を介して前記半導体基板の第１導電型層に電気的に接続されている請求項１又は２のいずれか１項記載の結晶系太陽電池セル。 The said light-receiving surface electrode is electrically connected to the 1st conductivity type layer of the said semiconductor substrate through the connection film which consists of an electroconductive sintered compact containing a glass frit. The crystalline solar cell described.
  4. 　前記受光面電極が、前記半導体基板の第１導電型層上に設けられた第１の受光面電極と、当該第１の受光面電極上に設けられた第２の受光面電極とを有し、前記第１の受光面電極が、前記導電性焼結体からなる第１の接続膜を介して前記半導体基板の前記第１導電型層に電気的に接続されるとともに、前記第２の受光面電極が、前記導電性焼結体からなる第２の接続膜を介して前記第１の受光面電極に電気的に接続されている請求項３記載の結晶系太陽電池セル。 The light-receiving surface electrode has a first light-receiving surface electrode provided on the first conductivity type layer of the semiconductor substrate and a second light-receiving surface electrode provided on the first light-receiving surface electrode. The first light-receiving surface electrode is electrically connected to the first conductivity type layer of the semiconductor substrate through a first connection film made of the conductive sintered body, and the second light-receiving surface electrode The crystalline solar cell according to claim 3, wherein a surface electrode is electrically connected to the first light-receiving surface electrode through a second connection film made of the conductive sintered body.
  5. 　光入射側の表面側に第１導電型層を有し、かつ、裏面側に第２導電型層を有する半導体基板の第１導電型層上に、反射防止膜が設けられた太陽電池用基板を用意し、
    　ガラスフリットを含有する導電性ペーストを用い、当該導電性ペーストを焼結させることにより、導体からなるボンディングワイヤによって構成された受光面電極を前記太陽電池用基板上に固着するとともに、当該受光面電極を前記半導体基板の第１導電型層に対して電気的に接続させる工程を有する結晶系太陽電池セルの製造方法。     A solar cell substrate in which an antireflection film is provided on a first conductivity type layer of a semiconductor substrate having a first conductivity type layer on the front surface side on the light incident side and a second conductivity type layer on the back surface side. Prepare
    By using a conductive paste containing glass frit and sintering the conductive paste, the light-receiving surface electrode constituted by a bonding wire made of a conductor is fixed on the solar cell substrate, and the light-receiving surface electrode A method for manufacturing a crystalline solar cell, comprising a step of electrically connecting a semiconductor substrate to a first conductivity type layer of the semiconductor substrate.
  6. 　請求項５において、前記受光面電極が、第１及び第２の受光面電極を備え、
    　前記反射防止膜上に前記導電性ペーストを塗布乾燥して第１の接続膜を形成する工程と、
    　前記第１の接続膜上に前記第１の受光面電極を配置する工程と、
    　前記第１の接続膜を焼結させる工程と、
    　前記第１の受光面電極上に前記導電性ペーストを塗布乾燥して第２の接続膜を形成する工程と、
    　前記第２の接続膜を焼結させる工程とを有する結晶系太陽電池セルの製造方法。     6. The light receiving surface electrode according to claim 5, wherein the light receiving surface electrode includes first and second light receiving surface electrodes,
    Applying and drying the conductive paste on the antireflection film to form a first connection film;
    Disposing the first light-receiving surface electrode on the first connection film;
    Sintering the first connection film;
    Applying and drying the conductive paste on the first light-receiving surface electrode to form a second connection film;
    A method for producing a crystalline solar cell, comprising a step of sintering the second connection film.
  7. 　請求項５において、前記ボンディングワイヤに前記導電性ペーストを塗布乾燥して接続膜を形成した受光面電極を用意し、
    　前記受光面電極を前記太陽電池用基板上に配置する工程と、
    　前記受光面電極の接続膜を焼結させる工程とを有する結晶系太陽電池セルの製造方法。     In Claim 5, the light-receiving surface electrode which prepared the connection film by applying and drying the conductive paste on the bonding wire is prepared,
    Arranging the light receiving surface electrode on the solar cell substrate;
    And a step of sintering the connection film of the light-receiving surface electrode.
  8. 　前記導電性ペーストを塗布する工程が、ディスペンサ法又はインクジェット法によるものである請求項５乃至７のいずれか１項記載の結晶系太陽電池セルの製造方法。  The method for producing a crystalline solar cell according to any one of claims 5 to 7, wherein the step of applying the conductive paste is performed by a dispenser method or an ink jet method.
PCT/JP2010/059913 2010-06-11 2010-06-11 Crystalline solar battery cell and process for production thereof WO2011155052A1 (en)

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