JP2010186864A - Method of manufacturing solar cell, and solar cell - Google Patents

Method of manufacturing solar cell, and solar cell Download PDF

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JP2010186864A
JP2010186864A JP2009029869A JP2009029869A JP2010186864A JP 2010186864 A JP2010186864 A JP 2010186864A JP 2009029869 A JP2009029869 A JP 2009029869A JP 2009029869 A JP2009029869 A JP 2009029869A JP 2010186864 A JP2010186864 A JP 2010186864A
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electrode
semiconductor substrate
solar cell
conductive paste
organic solvent
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JP5332683B2 (en
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Noribumi Takahashi
紀文 高橋
Takenori Watabe
武紀 渡部
Hiroyuki Otsuka
寛之 大塚
Naoki Ishikawa
直揮 石川
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Shin Etsu Chemical Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell which compatibly has low contact resistance and wiring resistance of an electrode and has higher conversion efficiency while maintaining high adhesive strength and yield by dipping a semiconductor substrate, having the electrode formed of conductive paste, into water, a specified organic solvent, or a mixed solvent thereof. <P>SOLUTION: A method of manufacturing the solar cell is characterized by: coating a surface of the semiconductor substrate, having a p-n junction formed, with the conductive paste containing conductive particles and glass frits; heat-treating the semiconductor substrate coated with the conductive paste to form the electrode by burning the conductive paste; and then dipping the semiconductor substrate having the electrode formed into the water, the organic solvent, or the mixed solvent thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、太陽電池の製造方法及び太陽電池に関する。   The present invention relates to a solar cell manufacturing method and a solar cell.

太陽電池には、太陽光の光エネルギーを電気エネルギーに変換するpn接合を有する半導体基板部分と、その半導体基板から電気エネルギーを外部に取り出す径路となる電極部分とがある。この両者の界面付近では、通常、材料の不連続性のために電気的接触抵抗が生じる。この電気的接触抵抗は、太陽電池から取り出せる電気エネルギーを減少させ、太陽電池の効率を減少させてしまう。   A solar cell includes a semiconductor substrate portion having a pn junction that converts light energy of sunlight into electric energy, and an electrode portion serving as a path for extracting electric energy from the semiconductor substrate to the outside. In the vicinity of the interface between the two, an electrical contact resistance usually occurs due to the discontinuity of the material. This electrical contact resistance reduces the electrical energy that can be extracted from the solar cell, reducing the efficiency of the solar cell.

結晶系太陽電池に使用されている代表的な電極材料として、塊状又は小片状の金属粒子を含有した導電性ペーストがある。導電性ペーストによる電極形成は、電極形成方法としてスクリーン印刷を適用できることなどの理由から広く普及している。このような方法により形成された表面電極と半導体基板との接触抵抗と、電極の配線抵抗は、太陽電池の変換効率に大きな影響を及ぼし、高効率(低セル直列抵抗、高フィルファクター(曲線因子))を得るためには、コンタクト抵抗と表面電極の配線抵抗の値が十分に低いことが要求される。   As a typical electrode material used for a crystalline solar cell, there is a conductive paste containing massive or small metal particles. Electrode formation with a conductive paste is widely used because screen printing can be applied as an electrode formation method. The contact resistance between the surface electrode and the semiconductor substrate formed by such a method and the wiring resistance of the electrode have a great influence on the conversion efficiency of the solar cell, and the high efficiency (low cell series resistance, high fill factor (curve factor) In order to obtain ()), the contact resistance and the wiring resistance value of the surface electrode are required to be sufficiently low.

この導電性ペーストによる電極と半導体基板との間の接触抵抗を低減する方法として、導電性ペーストを半導体基板上に印刷し、焼成を行って電極を形成した後に、太陽電池を酸に浸漬する方法や、電極をはんだフラックスで処理する方法がある(例えば、特許文献1:特開平9−213979号公報参照)。   As a method of reducing the contact resistance between the electrode and the semiconductor substrate due to the conductive paste, a method of immersing the solar cell in an acid after the conductive paste is printed on the semiconductor substrate and baked to form the electrode Alternatively, there is a method of treating an electrode with a solder flux (see, for example, Patent Document 1: Japanese Patent Laid-Open No. 9-213979).

しかしながら、酸への浸漬処理を行った場合、基板への電極の密着強度が低下するという問題点がある。また、はんだで被覆する方法の場合、はんだ槽への浸漬時に熱衝撃によって基板に割れが発生するおそれがあり、歩留まりが低下するという問題点がある。   However, when the immersion treatment in acid is performed, there is a problem that the adhesion strength of the electrode to the substrate is lowered. Further, in the case of the method of covering with solder, there is a possibility that the substrate may be cracked by thermal shock when immersed in the solder bath, and there is a problem that the yield decreases.

特開平9−213979号公報JP-A-9-213979

本発明は上記事情に鑑みてなされたもので、電極及び半導体基板間の高い接着強度と歩留まりを維持したまま、低い接触抵抗と電極の配線抵抗を両立し、高い変換効率を有する太陽電池を製造する方法及びこれにより得られた太陽電池を提供することを目的とする。   The present invention has been made in view of the above circumstances, and manufactures a solar cell having both high contact efficiency and high wiring conversion efficiency while maintaining high adhesion strength and yield between the electrode and the semiconductor substrate. It is an object of the present invention to provide a method and a solar cell obtained thereby.

本発明者らは、上記目的を達成するために鋭意検討を重ねた結果、pn接合を形成した半導体基板の表面に、導電性粒子とガラスフリットを含有する導電性ペーストを塗布し、該導電性ペーストを塗布した半導体基板を熱処理して該導電性ペーストを焼成してなる電極を形成した後、この電極が形成された半導体基板を水、有機溶媒又はこれらの混合溶媒に浸漬して電極内に残存している不導体成分を除去することで、電極と基板間の接触抵抗、電極の配線抵抗を低減することができ、その結果、高い変換効率を有する太陽電池を提供することができることを見出し、本発明を成すに至った。   As a result of intensive studies to achieve the above object, the present inventors applied a conductive paste containing conductive particles and glass frit to the surface of a semiconductor substrate on which a pn junction was formed, After the semiconductor substrate coated with the paste is heat-treated to form an electrode formed by firing the conductive paste, the semiconductor substrate on which the electrode is formed is immersed in water, an organic solvent or a mixed solvent thereof to be immersed in the electrode. It has been found that by removing the remaining non-conductive component, the contact resistance between the electrode and the substrate and the wiring resistance of the electrode can be reduced, and as a result, a solar cell having high conversion efficiency can be provided. The present invention has been achieved.

即ち、本発明は、下記の太陽電池の製造方法及び太陽電池を提供する。
請求項1:
pn接合を形成した半導体基板の表面に、導電性粒子とガラスフリットを含有する導電性ペーストを塗布し、該導電性ペーストを塗布した半導体基板を熱処理して該導電性ペーストを焼成してなる電極を形成した後、この電極が形成された半導体基板を水、有機溶媒又はこれらの混合溶媒に浸漬することを特徴とする太陽電池の製造方法。
請求項2:
前記有機溶媒が、アルコール、エーテル、アミン、ピロリドン、ケトン、ラクトン、エステル、スルホキシド、ハロゲン化物、芳香族化合物及び脂肪族化合物からなる群より選ばれる1種又は2種以上の溶媒である請求項1記載の製造方法。
請求項3:
請求項1又は2記載の製造方法によって得られる太陽電池。
That is, this invention provides the manufacturing method and solar cell of the following solar cell.
Claim 1:
An electrode formed by applying a conductive paste containing conductive particles and glass frit to the surface of a semiconductor substrate on which a pn junction has been formed, and heat-treating the semiconductor substrate to which the conductive paste has been applied. Then, the semiconductor substrate on which this electrode is formed is immersed in water, an organic solvent, or a mixed solvent thereof.
Claim 2:
2. The organic solvent is one or more solvents selected from the group consisting of alcohol, ether, amine, pyrrolidone, ketone, lactone, ester, sulfoxide, halide, aromatic compound and aliphatic compound. The manufacturing method as described.
Claim 3:
The solar cell obtained by the manufacturing method of Claim 1 or 2.

導電性ペーストにより電極が形成された半導体基板を水又は特定の有機溶媒あるいはこれらの混合溶媒に浸漬することにより、高い接着強度と歩留まりを維持したまま、低い接触抵抗と電極の配線抵抗を両立し、より高い変換効率を有する太陽電池を提供することができる。   By immersing the semiconductor substrate on which the electrode is formed from the conductive paste in water or a specific organic solvent or a mixed solvent thereof, both low contact resistance and electrode wiring resistance can be achieved while maintaining high adhesive strength and yield. A solar cell having higher conversion efficiency can be provided.

本発明の太陽電池の製造方法は、pn接合を形成した半導体基板の表面に、導電性粒子とガラスフリットを含有する導電性ペーストを塗布し、該導電性ペーストを塗布した半導体基板を熱処理して該導電性ペーストを焼成してなる電極を形成した後、この電極が形成された半導体基板を水、有機溶媒又はこれらの混合溶媒に浸漬するものである。   In the method for manufacturing a solar cell of the present invention, a conductive paste containing conductive particles and glass frit is applied to the surface of a semiconductor substrate on which a pn junction is formed, and the semiconductor substrate to which the conductive paste is applied is heat-treated. After forming an electrode formed by firing the conductive paste, the semiconductor substrate on which the electrode is formed is immersed in water, an organic solvent, or a mixed solvent thereof.

まず、本発明の太陽電池に用いられる電極付き半導体基板の作製方法は特に制限されず、一例を以下に述べると、半導体基板として高純度シリコンに、ホウ素、ガリウム等のIII族元素をドープし、比抵抗0.1〜5Ω・cmとしたアズカット単結晶{100}p型シリコン基板表面のスライスダメージを、濃度5〜60質量%の水酸化ナトリウムや水酸化カリウム等の高濃度のアルカリ、もしくは、ふっ酸と硝酸とを体積比で30:70〜10:90で混合した混酸等を用いてエッチングする。エッチングは30〜90℃、特に50〜80℃で行うことが好ましく、通常エッチング時間は1〜30分間、特に5〜15分間である。   First, the method for producing the electrode-attached semiconductor substrate used in the solar cell of the present invention is not particularly limited, and an example is described below.High purity silicon as a semiconductor substrate is doped with a group III element such as boron or gallium, Slice damage on the surface of an as-cut single crystal {100} p-type silicon substrate having a specific resistance of 0.1 to 5 Ω · cm, a high concentration alkali such as sodium hydroxide or potassium hydroxide at a concentration of 5 to 60% by mass, or Etching is performed using a mixed acid in which hydrofluoric acid and nitric acid are mixed at a volume ratio of 30:70 to 10:90. Etching is preferably performed at 30 to 90 ° C., particularly 50 to 80 ° C., and the etching time is usually 1 to 30 minutes, particularly 5 to 15 minutes.

ここで、本発明で用いる単結晶シリコン基板の純度としては、鉄、アルミニウム、チタン等の金属不純物濃度が10-4ppm以下であり、ドーパント濃度が1015〜1017cm-3であることがライフタイム、比抵抗の点から好ましい。この単結晶シリコン基板は、CZ法、FZ法等のいずれの方法によって作製されたものでもよく、この場合、あらかじめ金属グレードシリコンをシーメンス法等の公知の方法により精製したものを上記方法に用いることもできる。 Here, as the purity of the single crystal silicon substrate used in the present invention, the concentration of metal impurities such as iron, aluminum, and titanium is 10 −4 ppm or less, and the dopant concentration is 10 15 to 10 17 cm −3. It is preferable from the viewpoint of lifetime and specific resistance. This single crystal silicon substrate may be produced by any method such as CZ method, FZ method, etc. In this case, a metal grade silicon previously purified by a known method such as Siemens method is used in the above method. You can also.

シリコン基板の厚みはハンドリング、長波長感度の点から50〜500μmが好ましく、より好ましくは100〜300μmである。また、単結晶シリコン基板の比抵抗が上記範囲より小さいとオージェ再結合によりライフタイムが低下する場合があり、大きいと内部抵抗が大きくなる場合がある。   The thickness of the silicon substrate is preferably 50 to 500 μm, more preferably 100 to 300 μm from the viewpoint of handling and long wavelength sensitivity. Further, if the specific resistance of the single crystal silicon substrate is smaller than the above range, the lifetime may be reduced by Auger recombination, and if it is larger, the internal resistance may be increased.

なお、本発明の太陽電池に用いられる基板としては、p型単結晶シリコン基板以外にも、リン、砒素等のV族元素をドープしたn型単結晶シリコン基板も上記と同様の方法により処理して用いることができ、p型又はn型多結晶シリコン基板、非シリコン系の化合物半導体基板等も使用することもできる。   In addition to the p-type single crystal silicon substrate, an n-type single crystal silicon substrate doped with a group V element such as phosphorus or arsenic is treated in the same manner as described above as the substrate used in the solar cell of the present invention. A p-type or n-type polycrystalline silicon substrate, a non-silicon based compound semiconductor substrate, or the like can also be used.

引き続き、基板表面にテクスチャとよばれる微小な凹凸形成を行う。テクスチャは、太陽電池の表面反射率を低下させるための有効な方法である。テクスチャは、加熱した水酸化ナトリウム、水酸化カリウム、炭酸カリウム、炭酸ナトリウム、炭酸水素ナトリウム等のアルカリ溶液(水溶液)(濃度1〜10質量%、温度60〜100℃)中に、10〜30分程度浸漬することで容易に作製される。上記条件を下回るとテクスチャが形成されない場合があり、上回るとテクスチャがつぶれてしまう場合がある。上記溶液中に、所定量の2−プロパノール等を溶液全体の1〜25質量%溶解させ、反応を促進させることが好ましい。   Subsequently, minute unevenness called texture is formed on the substrate surface. Texture is an effective way to reduce the surface reflectance of solar cells. Texture is 10-30 minutes in heated alkaline solution (aqueous solution) of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, etc. (concentration 1-10 mass%, temperature 60-100 ° C.). It is easily produced by soaking to a certain extent. If it falls below the above conditions, the texture may not be formed, and if it exceeds, the texture may be crushed. It is preferable to dissolve 1 to 25% by mass of a predetermined amount of 2-propanol or the like in the above solution to promote the reaction.

テクスチャ形成後、塩酸、硫酸、硝酸、ふっ酸等の無機酸の1種単独又は2種以上を併用した混合液の酸性水溶液中で洗浄する。経済的及び効率的見地から、塩酸中での洗浄が好ましい。酸濃度は1〜10質量%が好ましく、清浄度を向上させるため、酸性溶液中に、0.5〜5質量%の過酸化水素を混合させ、60〜90℃で2〜30分間加温して洗浄してもよい。   After texture formation, washing is carried out in an acidic aqueous solution of a mixed solution using one kind or two or more kinds of inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid. From an economic and efficient standpoint, washing in hydrochloric acid is preferred. The acid concentration is preferably 1 to 10% by mass. In order to improve cleanliness, 0.5 to 5% by mass of hydrogen peroxide is mixed in an acidic solution and heated at 60 to 90 ° C. for 2 to 30 minutes. May be washed.

この基板上に、オキシ塩化リン等を用いた気相拡散法によりエミッタ層を形成する。この場合、オキシ塩化リン等の雰囲気下で、800〜900℃で10〜60分間熱処理することが好ましい。また、エミッタ層の厚さは0.1〜2μmが好ましく、より好ましくは0.2〜1.2μmである。厚すぎると短波長感度が低下する場合があり、薄すぎると内部抵抗が増加する場合がある。   An emitter layer is formed on this substrate by vapor phase diffusion using phosphorus oxychloride or the like. In this case, heat treatment is preferably performed at 800 to 900 ° C. for 10 to 60 minutes in an atmosphere such as phosphorus oxychloride. Further, the thickness of the emitter layer is preferably 0.1 to 2 μm, and more preferably 0.2 to 1.2 μm. If it is too thick, the short wavelength sensitivity may decrease, and if it is too thin, the internal resistance may increase.

一般的なシリコン太陽電池は、pn接合を受光面にのみ形成する必要があり、これを達成するために基板同士を2枚重ね合わせた状態で拡散したり、拡散前に裏面にSiO2膜やSiNx膜などを拡散マスクとして形成して、裏面にpn接合ができないような工夫を施すことが好ましい。拡散後、表面にできたリンガラスを1〜25質量%程度のふっ酸(水溶液)などで除去する。
なお、エミッタ層の形成は、上記気相拡散法以外にも、ペースト印刷、スピンコート、イオン注入等により行うこともできる。
In general silicon solar cells, it is necessary to form a pn junction only on the light-receiving surface, and in order to achieve this, diffusion is performed in a state where two substrates are overlapped, or a SiO 2 film or the like is formed on the back surface before diffusion. It is preferable that a SiN x film or the like is formed as a diffusion mask so that a pn junction cannot be formed on the back surface. After diffusion, the phosphorous glass formed on the surface is removed with about 1 to 25% by mass hydrofluoric acid (aqueous solution).
Note that the emitter layer can be formed by paste printing, spin coating, ion implantation, or the like in addition to the vapor phase diffusion method.

次に、受光面の反射防止膜形成を行う。製膜にはプラズマCVD装置等を用い、SiNx膜、TiO2、Al23、MgF、SiO2、SiO、Ta25、ZnS等を約50〜150nmの膜厚に製膜する。SiNx膜を形成する場合、反応ガスとして、モノシラン(SiH4)及びアンモニア(NH3)を混合して用いることが多いが、NH3の代わりに窒素を用いることも可能であり、また、プロセス圧力の調整、反応ガスの希釈、さらには、基板に多結晶シリコンを用いた場合には、基板のバルクパッシベーション効果を促進するため、反応ガスに水素を混合することもある。
この場合、シランとアンモニアとの混合割合はモル比で、1:1〜1:5であることが好ましい。また、窒素ガスを用いる場合、全体の30モル%程度が好ましく、水素ガスは全体の30モル%程度が好ましい。
Next, an antireflection film is formed on the light receiving surface. A SiN x film, TiO 2 , Al 2 O 3 , MgF, SiO 2 , SiO, Ta 2 O 5 , ZnS, or the like is formed to a film thickness of about 50 to 150 nm using a plasma CVD apparatus or the like. When forming a SiN x film, monosilane (SiH 4 ) and ammonia (NH 3 ) are often used as a reaction gas in combination, but nitrogen can be used instead of NH 3 , and the process When the pressure is adjusted, the reaction gas is diluted, or polycrystalline silicon is used for the substrate, hydrogen may be mixed into the reaction gas in order to promote the bulk passivation effect of the substrate.
In this case, the mixing ratio of silane and ammonia is preferably 1: 1 to 1: 5 in molar ratio. Moreover, when using nitrogen gas, about 30 mol% of the whole is preferable, and about 30 mol% of hydrogen gas is preferable.

次いで、裏面電極及び受光面の電極をスクリーン印刷法等で形成する。スクリーン印刷法では、上記基板の裏面に、例えば、Al粉末等の導電性粒子、ガラスフリット、有機物バインダ等を混合したペーストをスクリーン印刷する。印刷後、1〜30分間、特に5〜10分間、700〜900℃、特に750〜800℃の温度で焼成して、裏面電極が形成される。裏面電極形成は、印刷法によるほうが好ましいが、蒸着法、スパッタ法等で作製することも可能である。また、電極の形状は基板裏面全面に形成しても、櫛形等に形成してもよい。   Next, the back electrode and the light receiving electrode are formed by a screen printing method or the like. In the screen printing method, a paste in which conductive particles such as Al powder, glass frit, organic binder, and the like are mixed is screen-printed on the back surface of the substrate. After printing, the back electrode is formed by firing at a temperature of 700 to 900 ° C., particularly 750 to 800 ° C., for 1 to 30 minutes, particularly 5 to 10 minutes. The back electrode is preferably formed by a printing method, but can also be produced by a vapor deposition method, a sputtering method, or the like. Further, the shape of the electrode may be formed on the entire back surface of the substrate or may be formed in a comb shape or the like.

受光面電極もスクリーン印刷法等を用いることができる。例えば、Ag粉末等の導電性粒子、ガラスフリット、有機物バインダ等を混合したAgペーストをスクリーン印刷した後、600〜900℃、特に650〜800℃で1〜30分間、特に5〜10分間の熱処理によりSiNx膜に銀粉末を貫通させ(ファイアースルー)、電極とシリコンを導通させる。この際、受光面電極の形状は特に制限されない。この場合、裏面電極及び受光面電極の焼成は、一度に行うことも可能である。また、電極と基板の接触抵抗を下げるために、電極焼成後に接着強度が損なわれない程度に0.1〜5質量%の低濃度の酸へ10〜300秒程度の短時間浸漬処理を行ってもよい。 A screen printing method or the like can also be used for the light receiving surface electrode. For example, after screen printing an Ag paste mixed with conductive particles such as Ag powder, glass frit, organic binder, etc., heat treatment at 600 to 900 ° C., particularly 650 to 800 ° C. for 1 to 30 minutes, especially 5 to 10 minutes By making silver powder penetrate through the SiN x film (fire through), the electrode and silicon are made conductive. At this time, the shape of the light receiving surface electrode is not particularly limited. In this case, the back electrode and the light-receiving surface electrode can be baked at a time. Also, in order to reduce the contact resistance between the electrode and the substrate, a short dipping treatment for about 10 to 300 seconds is performed in a low concentration acid of 0.1 to 5% by mass so that the adhesive strength is not impaired after the electrode is baked. Also good.

ここで、本発明において使用する電極用導電性ペーストとしては、裏面電極用としてはアルミニウム粉末を60〜90質量%、特に70〜80質量%含有し、ガラスフリットを0.1〜5質量%、特に0.5〜2質量%、有機物バインダを1〜10質量%、特に2〜5質量%含有するものが印刷性等の点において好ましい。一方、受光面電極用としては、銀粉末を60〜90質量%、特に70〜80質量%、ガラスフリットを0.1〜5質量%、特に0.5〜2質量%、上述した有機物バインダを1〜10質量%、特に2〜5質量%含有するものが印刷性等の点において好ましい。   Here, as the conductive paste for electrodes used in the present invention, it contains 60 to 90% by mass, particularly 70 to 80% by mass of aluminum powder for the back electrode, and 0.1 to 5% by mass of glass frit, In particular, those containing 0.5 to 2% by mass, 1 to 10% by mass, and particularly 2 to 5% by mass of an organic binder are preferable in terms of printability. On the other hand, for the light-receiving surface electrode, the silver powder is 60 to 90% by mass, particularly 70 to 80% by mass, the glass frit is 0.1 to 5% by mass, particularly 0.5 to 2% by mass, and the organic binder described above. What contains 1-10 mass%, especially 2-5 mass% is preferable in points, such as printability.

アルミニウム粉末及び銀粉末の平均粒径は、10μm以下が好ましく、より好ましくは5μm以下である。大きすぎると焼結性が悪くなる場合がある。また、ガラスフリットとしては、例えば、鉛ボロシリケートフリット、ビスマス、バリウム、カルシウム又は他のアルカリ土族ボロシリケートフリット等を含有するホウケイ酸塩系のものを用いることができる。   The average particle size of the aluminum powder and the silver powder is preferably 10 μm or less, more preferably 5 μm or less. If it is too large, the sinterability may deteriorate. Further, as the glass frit, for example, a borosilicate-based one containing lead borosilicate frit, bismuth, barium, calcium or other alkaline earth borosilicate frit can be used.

このような導電性ペーストとしては、市販のものを使用することができ、例えば、デュポン社製のSolamet(登録商標)等を用いることができる。   As such an electrically conductive paste, a commercially available thing can be used, for example, Solamet (trademark) by DuPont etc. can be used.

本発明においては、このようにして得られた電極付き半導体基板を、水、有機溶媒又はこれらの混合溶媒に浸漬する。有機溶媒としては、アルコール類、エーテル類、アミン類、ピロリドン類、ケトン類、ラクトン類、エステル類、スルホキシド類、ハロゲン化物類、芳香族化合物類及び脂肪族化合物類からなる群より選ばれる1種単独の溶媒又は2種以上の混合溶媒に0〜150℃、特に20〜100℃で1〜30分間、特に5〜15分間浸漬させる。   In the present invention, the electrode-attached semiconductor substrate thus obtained is immersed in water, an organic solvent, or a mixed solvent thereof. The organic solvent is one selected from the group consisting of alcohols, ethers, amines, pyrrolidones, ketones, lactones, esters, sulfoxides, halides, aromatic compounds and aliphatic compounds. It is immersed in a single solvent or two or more mixed solvents at 0 to 150 ° C., particularly 20 to 100 ° C. for 1 to 30 minutes, particularly 5 to 15 minutes.

上記有機溶媒として具体的には、メチルアルコール、エチルアルコール、イソプロピルアルコール、1−プロパノール、ブタノール類、n−ヘキサノール、ヘプタノール類、オクタノール類、2−エチルヘキサノール、アミルアルコール類、n−オクタノール、フルフリルアルコール、テトラヒドロフルフリルアルコール、ベンジルアルコール等のアルコール類;
エピクロルヒドリン、グリシジルメチルエーテル、酸化プロピレン、テトラヒドロフラン、ジメチルエーテル、ジエチルエーテル、ジブチルエーテル、ジオキサン、トリオキサン、フラン、フルフラール等のエーテル類;
N,N−ジメチルホルムアミド、N,N−ジエチルホルムアミド、N,N−ジメチルアセトアミド、N,N−ジエチルアセトアミド等のアミン類;
N−メチルピロリドン、N−エチルピロリドン、N−プロピルピロリドン等のピロリドン類;
アクロレイン、アセトン、アセトアルデヒド、アセトフェノン、ジエチルケトン、メチルエチルケトン、ジイソブチルケトン、ジイソプロピルケトン、シクロヘキサノン、メチルイソブチルケトン、メチル−n−ブチルケトン、ホロン、イソホロン等のケトン類;
γ−ブチロラクトン、γ−バレロラクトン、δ−バレロラクトン、3−メチル−1,3−オキサゾリジン−2−オン及び3−エチル−1,3−オキサゾリジン−2−オン等のラクトン類;
酢酸メチル、酢酸エチル、酢酸ブチル、酢酸プロピル、酪酸メチル、酪酸エチル、酪酸ブチル、酪酸プロピル、フタル酸ジエチル、フタル酸ジオクチル等のエステル類;
ジメチルスルホキシド、ジエチルスルホキシド等のスルホキシド類;
クロロホルム、ジクロロメタン、ジクロロエタン等のハロゲン化物類;
ベンゼン、トルエン、キシレン、メシチレン、n−ブチルベンゼン、ジエチルベンゼン、テトラリン、メトキシベンゼン、1,2−ジメトキシベンゼン等の芳香族化合物類;
ヘキサン、シクロヘキサン、メチルシクロヘキサン、ペンタン、シクロペンタン、オクタン、ノナン、デカン等の脂肪族化合物類が挙げられる。
混合溶媒を用いる場合、例えば、水、アルコール等を用いることができ、混合割合(質量比)は、水:アルコール=10:90〜50:50が好ましい。
Specific examples of the organic solvent include methyl alcohol, ethyl alcohol, isopropyl alcohol, 1-propanol, butanols, n-hexanol, heptanols, octanols, 2-ethylhexanol, amyl alcohols, n-octanol, and furfuryl. Alcohols such as alcohol, tetrahydrofurfuryl alcohol, benzyl alcohol;
Ethers such as epichlorohydrin, glycidyl methyl ether, propylene oxide, tetrahydrofuran, dimethyl ether, diethyl ether, dibutyl ether, dioxane, trioxane, furan, furfural;
Amines such as N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide;
Pyrrolidones such as N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone;
Ketones such as acrolein, acetone, acetaldehyde, acetophenone, diethyl ketone, methyl ethyl ketone, diisobutyl ketone, diisopropyl ketone, cyclohexanone, methyl isobutyl ketone, methyl-n-butyl ketone, holon, isophorone;
Lactones such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, 3-methyl-1,3-oxazolidine-2-one and 3-ethyl-1,3-oxazolidine-2-one;
Esters such as methyl acetate, ethyl acetate, butyl acetate, propyl acetate, methyl butyrate, ethyl butyrate, butyl butyrate, propyl butyrate, diethyl phthalate, dioctyl phthalate;
Sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide;
Halides such as chloroform, dichloromethane, dichloroethane;
Aromatic compounds such as benzene, toluene, xylene, mesitylene, n-butylbenzene, diethylbenzene, tetralin, methoxybenzene, 1,2-dimethoxybenzene;
Aliphatic compounds such as hexane, cyclohexane, methylcyclohexane, pentane, cyclopentane, octane, nonane, and decane are listed.
In the case of using a mixed solvent, for example, water, alcohol, or the like can be used, and the mixing ratio (mass ratio) is preferably water: alcohol = 10: 90 to 50:50.

これらのなかでも、コスト、安全性の点から水、アルコール類の溶媒を好適に使用することができる。   Among these, water and alcohol solvents can be preferably used from the viewpoint of cost and safety.

上記溶媒に浸漬することで、電極内に残存するバインダー、チクソ剤等の不導体成分を溶解・溶出することで除去することができる。
浸漬後は、20〜200℃で5〜60分間乾燥することが好ましい。
By immersing in the solvent, non-conductive components such as binder and thixotropic agent remaining in the electrode can be removed by dissolution and elution.
After immersion, it is preferable to dry at 20 to 200 ° C. for 5 to 60 minutes.

以下、実施例及び比較例を示し、本発明をより具体的に説明するが、本発明は下記の実施例に制限されるものではない。   EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example.

[実施例1]
拡散厚さ250μm、比抵抗1Ω・cmの、ホウ素ドープ{100}p型アズカットシリコン基板100枚に対し、80℃の25質量%熱濃水酸化カリウム水溶液によりダメージ層を除去後、5質量%水酸化カリウム/2−プロパノール水溶液(混合割合(体積比)2−プロパノール/水=5/95)中に浸漬し、テクスチャ形成を行い、引き続き塩酸/過酸化水素混合溶液(混合割合(体積比)塩酸/過酸化水素/水=0.5/1/10)中で洗浄を行った。
[Example 1]
5% by mass after removing the damage layer with 100% boron doped {100} p-type ascut silicon substrate having a diffusion thickness of 250 μm and a specific resistance of 1 Ω · cm with a 25% by mass hot concentrated potassium hydroxide aqueous solution at 80 ° C. It is immersed in an aqueous solution of potassium hydroxide / 2-propanol (mixing ratio (volume ratio) 2-propanol / water = 5/95), textured, and subsequently mixed with hydrochloric acid / hydrogen peroxide (mixing ratio (volume ratio)). Washing was performed in hydrochloric acid / hydrogen peroxide / water = 0.5 / 1/10).

次に、オキシ塩化リン雰囲気下、870℃で裏面同士を重ねた状態で熱処理し、エミッタ層(厚さ500nm)を形成した。拡散後、25質量%ふっ酸にてリンガラスを除去し、洗浄、乾燥させた。
以上の処理の後、プラズマCVD装置を用いてSiNx膜(膜厚80nm)を受光面反射防止膜として全試料に対して形成した。
Next, it heat-processed in the phosphorus oxychloride atmosphere in the state which accumulated the back surfaces at 870 degreeC, and formed the emitter layer (thickness 500nm). After diffusion, the phosphorus glass was removed with 25% by mass hydrofluoric acid, washed and dried.
After the above processing, a SiN x film (film thickness of 80 nm) was formed as a light-receiving surface antireflection film on all samples using a plasma CVD apparatus.

次に、裏面電極としてAlペーストを裏面全面にスクリーン印刷し、100℃で乾燥した。続いて、受光面の第一電極層としてAgペーストを、印刷して700℃で乾燥した。その後、2−プロパノールに室温(25℃)で5分浸漬させた後、乾燥した。   Next, an Al paste as a back electrode was screen-printed on the entire back surface and dried at 100 ° C. Subsequently, an Ag paste was printed as a first electrode layer on the light receiving surface and dried at 700 ° C. Thereafter, it was immersed in 2-propanol at room temperature (25 ° C.) for 5 minutes and then dried.

変換効率及び曲線因子をソーラシミュレーター(NPC製)で測定した。さらに、受光面のバスバー電極にタブ線(2mm幅、160μm厚の平板銅線をはんだ被覆したもの)をはんだ付けして取り付け、タブ線をバスバー電極と平行方向に180度曲げて引っ張った場合の接着強度を測定した。接着強度の単位はN/2mmであり、2mm幅のタブ線を引っ張ったときの力(単位N)の測定値を示す。
このようにして得られた測定結果を表1に示す。有機溶媒浸漬による割れは見られず、歩留まりの低下は確認されなかった。接着強度の測定では、2N/2mmを超えた後、電極が剥がれる前に基板が破壊された。このことにより、接着強度は十分高いということがわかった。
Conversion efficiency and fill factor were measured with a solar simulator (NPC). Further, when the tab wire (2 mm width and 160 μm thick flat copper wire is solder coated) is attached to the bus bar electrode on the light receiving surface by soldering, and the tab wire is bent 180 degrees parallel to the bus bar electrode and pulled. The adhesive strength was measured. The unit of adhesive strength is N / 2 mm, and shows the measured value of force (unit N) when a tab wire having a width of 2 mm is pulled.
The measurement results obtained in this way are shown in Table 1. Cracks due to immersion in an organic solvent were not observed, and a decrease in yield was not confirmed. In the measurement of the adhesive strength, after exceeding 2N / 2 mm, the substrate was destroyed before the electrode was peeled off. This proves that the adhesive strength is sufficiently high.

[比較例1]
電極の焼成を行った後に、本発明の有機溶媒処理を行わなかった他は、実施例1と同様にして、太陽電池の変換効率、曲線因子及び接着強度を測定した。結果を表1に示す。
[Comparative Example 1]
After the electrode was baked, the conversion efficiency, the fill factor, and the adhesive strength of the solar cell were measured in the same manner as in Example 1 except that the organic solvent treatment of the present invention was not performed. The results are shown in Table 1.

Figure 2010186864
Figure 2010186864

Claims (3)

pn接合を形成した半導体基板の表面に、導電性粒子とガラスフリットを含有する導電性ペーストを塗布し、該導電性ペーストを塗布した半導体基板を熱処理して該導電性ペーストを焼成してなる電極を形成した後、この電極が形成された半導体基板を水、有機溶媒又はこれらの混合溶媒に浸漬することを特徴とする太陽電池の製造方法。   An electrode formed by applying a conductive paste containing conductive particles and glass frit to the surface of a semiconductor substrate on which a pn junction has been formed, and heat-treating the semiconductor substrate to which the conductive paste has been applied. Then, the semiconductor substrate on which this electrode is formed is immersed in water, an organic solvent, or a mixed solvent thereof. 前記有機溶媒が、アルコール、エーテル、アミン、ピロリドン、ケトン、ラクトン、エステル、スルホキシド、ハロゲン化物、芳香族化合物及び脂肪族化合物からなる群より選ばれる1種又は2種以上の溶媒である請求項1記載の製造方法。   2. The organic solvent is one or more solvents selected from the group consisting of alcohol, ether, amine, pyrrolidone, ketone, lactone, ester, sulfoxide, halide, aromatic compound and aliphatic compound. The manufacturing method as described. 請求項1又は2記載の製造方法によって得られる太陽電池。   The solar cell obtained by the manufacturing method of Claim 1 or 2.
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