JP2004179334A - Method of forming solar cell element - Google Patents

Method of forming solar cell element Download PDF

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Publication number
JP2004179334A
JP2004179334A JP2002342878A JP2002342878A JP2004179334A JP 2004179334 A JP2004179334 A JP 2004179334A JP 2002342878 A JP2002342878 A JP 2002342878A JP 2002342878 A JP2002342878 A JP 2002342878A JP 2004179334 A JP2004179334 A JP 2004179334A
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metal
semiconductor substrate
paste
electrode
solar cell
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Japanese (ja)
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Yuko Fukawa
祐子 府川
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Kyocera Corp
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Kyocera Corp
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    • 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

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a solar cell element which is capable of preventing an electrode from separating and superior in output characteristics. <P>SOLUTION: An opposite conductivity-type semiconductor impurity is diffused into one main surface of one conductivity-type semiconductor substrate 1, a surface electrode 4 whose main component is a first metal is formed on the main surface of the semiconductor substrate, a back electrode composed of a current collector 5 whose main component is a second metal, and an output port 6 whose main component is a third metal more easily solder-wettable than the second metal is formed on the other main surface of the semiconductor substrate for the formation of the solar cell element. Paste which is mainly formed of the first metal to serve as the surface electrode 4 is applied to the main surface of the semiconductor substrate 1, the substrate is subjected to first baking, paste which is mainly formed of the second metal to serve as the current collector 5 of the back electrode is applied on the other main surface of the semiconductor substrate 1, paste which is mainly formed of the third metal to serve as the output port 6 of the back electrode is applied on the other main surface, and then the substrate is subjected to second baking. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は太陽電池素子の形成方法に関し、特に金属ペーストを焼き付けて表面電極と裏面電極を形成する太陽電池素子の形成方法に関する。
【０００２】
【従来の技術および発明が解決しようとする課題】
従来の太陽電池素子を図１に示す。例えばＰ型半導体基板１の表面近傍の全面に一定の深さまでＮ型不純物を拡散させてＮ型を呈する拡散層２を設け、半導体基板１の表面に窒化シリコン膜などから成る反射防止膜３を設け、表面に表面電極４を設けるとともに、裏面にアルミニウムなどから成る集電部５と銀などから成る出力取出部６とで構成される裏面電極５、６を設けている。また半導体基板１の裏面には高濃度のＰ型拡散層７が形成される。
【０００３】
これらの太陽電池素子の表面電極４および裏面電極５、６を形成するには、アルミニウムからなる第二の金属を主成分とするペーストを半導体基板１の裏面の一部を除いた大部分に塗布して乾燥した後、この第二の金属を主成分とするペーストを塗布しなかった部分とその周縁部を覆うように銀からなる第三の金属を主成分とするペーストを塗布して乾燥し、最後に半導体基板１の表面に銀からなる第一の金属を主成分とするペーストを塗布して乾燥して、第一の金属を主成分とするペーストと第二の金属を主成分とするペーストと第三の金属を主成分とするペーストとを同時に焼成する方法、すなわち同時焼成法が従来用いられてきた（例えば特許文献１参照。）。
【０００４】
また、アルミニウムからなる第二の金属を主成分とするペーストを半導体基板１の裏面の一部を除いた大部分に塗布して乾燥した後、この第二の金属を主成分とするペーストを塗布しなかった部分とその周縁部を覆うように銀からなる第三の金属を主成分とするペーストを塗布して乾燥して１回目の焼成を行った後、半導体基板１の表面に銀からなる第一の金属を主成分とするペーストを塗布して乾燥して２回目の焼成を行う方法もある（例えば特許文献１参照。）。
【０００５】
さらに、アルミニウムからなる第二の金属を主成分とするペーストを半導体基板１の裏面の一部を除いた大部分に塗布して乾燥して１回目の焼成を行った後、この第二の金属を主成分とするペーストを塗布しなかった部分とその周縁部を覆うように銀からなる第三の金属を主成分とするペーストを塗布して乾燥した後、半導体基板１の表面に銀からなる第一の金属を主成分とするペーストを塗布して乾燥して２回目の焼成を行う方法もある（例えば特許文献１参照。）。
【０００６】
これによって半導体基板１の裏面には、集電部５とはんだ濡れ性の良好な出力取出部６が形成されるとともに、集電部５の下の半導体基板１には高濃度のＰ型拡散層７が形成される。
【０００７】
その後、表面電極４および裏面電極の出力取出部６上にはんだ（不図示）を被着して、太陽電池素子を直列もしくは並列に接続するインナーリードを接続する。
【０００８】
しかしこれらの方法によると、表面電極４が形成時もしくはそれ以降に剥離するという問題が発生することがあった。すなわち、図２および図３からわかるように表面電極４や出力取出部６の面積に比べ、集電部５の面積が広く使用するペースト量も多く、これらのペーストは金属の他に溶剤とエチルセルロース等のバインダーを混合して構成されるため、集電部５を焼成する際に揮発する溶剤やバインダーの成分が飛散し、半導体基板１の表面を汚染したり表面電極４の焼結を阻害するためにこの剥離の問題は発生するものと思われる。なお、図２は一般的な太陽電池素子の表面電極の構造を示し、図３は裏面電極の構造を示す。
【０００９】
この問題を解決する方法としては裏面電極の集電部５を形成した後に、半導体基板１の表面を洗浄して、その後表面電極４を形成する方法が考えられる。しかし、この方法を行うと工程数が増加してしまい製造上不適である。
【００１０】
さらに半導体基板１の表面に銀からなる第一の金属を主成分とするペーストを塗布して１回目の焼成を行い、アルミニウムからなる第二の金属を主成分とするペーストを半導体基板１の裏面の一部を除いた大部分に塗布して２回目の焼成を行った後、この第二の金属を主成分とするペーストを塗布しなかった部分とその周縁部を覆うように銀からなる第三の金属を主成分とするペーストを塗布して３回目の焼成を行う方法もある（例えば特許文献２参照。）。この方法によれば、集電部５を形成する前に表面電極４を形成してしまうため、上記のような剥離の問題は発生しない。
【００１１】
しかしこの方法によれば、表面電極４を形成した後、集電部５を形成し、更にその後に出力取出部６を形成するため、３回の高温焼成を繰り返すことになり、太陽電池素子の出力特性の低下の問題が発生したりすることがあった。そしてこの問題を回避するため、焼成温度を下げたり時間を短くしたりすると、裏面電極の集電部５と出力取出部６の間で剥離が発生してしまうという問題が発生することもあった。
【００１２】
本発明は、このような従来技術の問題点に鑑みてなされたものであり、電極の剥離の発生を防止するとともに、出力特性の良好な太陽電池素子の形成方法を提供することを目的とする。
【００１３】
【特許文献１】
特開平１０−３３５２６７号公報
【特許文献２】
特開２０００−１８８４０９号公報
【００１４】
【課題を解決するための手段】
上記目的を達成するために、本発明に係る太陽電池素子の形成方法では、一導電型を呈する半導体基板の一主面側に逆導電型半導体不純物を拡散するとともに、第一の金属を主成分とする表面電極を形成し、他の主面側に第二の金属を主成分とする集電部とこの第二の金属よりも半田濡れ性のよい第三の金属を主成分とする出力取出部とから成る裏面電極を形成する太陽電池素子の形成方法において、前記半導体基板の一主面側に前記表面電極となる第一の金属を主成分とするペーストを塗布して１回目の焼成を行った後、他の主面側に前記裏面電極の集電部となる第二の金属を主成分とするペーストを塗布するとともに、前記出力取出部となる第三の金属を主成分とするペーストを塗布して２回目の焼成を行うことを特徴とする。
【００１５】
上記太陽電池素子の形成方法では前記第一の金属と前記第三の金属は銀からなることが望ましい。
【００１６】
また上記太陽電池素子の形成方法では、前記半導体基板がシリコンからなり、前記第三の金属を主成分とするペーストにアルミニウムを含有することが望ましい。
【００１７】
また上記太陽電池素子の形成方法では、前記第二の金属がアルミニウムからなることが望ましい。
【００１８】
【発明の実施の形態】
以下、本発明の実施形態を詳細に説明する。
本発明に係る太陽電池素子の構造も基本的には従来の太陽電池素子と同様である。すなわち、例えばＰ型半導体基板１の表面近傍全面に一定の深さまでＮ型不純物を拡散させてＮ型を呈する拡散層２を設け、半導体基板１の表面に窒化シリコン膜などから成る反射防止膜３を設け、表面に表面電極４を設けるとともに、裏面にはアルミニウムなどから成る集電部５と銀などから成る出力取出部６とで構成される裏面電極を設けている。また半導体基板１の裏面には高濃度のＰ型拡散層７が形成される。
【００１９】
このような太陽電池素子は、例えばＰ型半導体基板１をＮ型不純物雰囲気中で熱処理などして、表面領域の全面に一定の深さまでＮ型不純物を拡散させてＮ型を呈する拡散層２を形成し、ＣＶＤ法などで反射防止膜３を形成して拡散層２を分離した後、表面電極４および集電部５と電極取出部６とから成る裏面電極が形成されるとともに、集電部５の下の半導体基板１に高濃度のＰ型拡散層７が形成される。
【００２０】
上記表面電極４、集電部５、および電極取出部６は、以下のように形成される。すなわち、半導体基板１の表面に表面電極４となる例えば銀からなる第一の金属を主成分とするペーストを塗布して約７００〜８００℃で１〜３０分程度の１回目の焼成を行う。このときの焼成温度が７００℃以下であったり、焼成時間が１分以下であったりすると、表面電極４の半導体基板１との接触抵抗を十分に低下させることができず太陽電池素子の特性低下を招くおそれがある。また、焼成温度が８００℃以上であったり、焼成時間が３０分以上であったりすると、拡散層２の不純物が再度拡散されることによって接合が深くなったり、表面電極４が拡散層２の接合を破壊するなどの問題が発生するおそれがある。
【００２１】
次に、半導体基板１の裏面に集電部５となるアルミニウムからなる第二の金属を主成分とするペーストを塗布するとともに、出力取出部６となる例えば銀からなる第三の金属を主成分とするペーストを塗布し、約６５０〜７８０℃で０．５〜２０分程度の２回目の焼成を行う。このときの焼成温度が６５０℃以下であったり、焼成時間が０．５分以下であったりすると、銀とアルミニウムが十分に焼結せずに剥離の原因となったり、接触抵抗が十分に低下しないなどの問題が発生するおそれがある。またアルミニウムが十分に半導体基板１に拡散されず、出力特性が低下するなどの問題が発生するおそれがある。反対に焼成温度が７８０℃以上であったり、焼成時間が２０分以上であったりすると、上記と同様に拡散層２の不純物が再度拡散されることによって接合が深くなったり、表面電極４が拡散層２の接合を破壊するなどの問題が発生するおそれがある。
【００２２】
この方法によれば、表面電極４の銀からなる第一の金属は１回目の焼成によって焼結する。したがって、その後半導体基板の裏面の大部分にアルミニウムからなる第二の金属を塗布し焼成しても、そのときに揮発するバインダーや溶剤によって表面電極の下の半導体基板表面が汚染されたり、第一の金属の焼結が阻害されるといった問題は発生せず、表面電極の剥離の問題を有効に回避できる。
【００２３】
そしてその後、集電部５のアルミニウムからなる第二の金属を主成分とするペーストと出力取出部６の銀からなる第三の金属を主成分とするペーストを同時に焼成するため、両者の重なり部では第二の金属と第三の金属の合金が形成されるため、この重なり部での剥離の問題は発生しない。
【００２４】
また、出力取出部６として塗布される銀からなる第三の金属を主成分とするペーストにはアルミニウムを含有することが望ましい。これにより第二の金属と第三の金属はより合金化しやすくなり、２回目の焼成の温度を下げたり時間を短くしたりしても剥離の問題を回避できるようになる。
【００２５】
このような金属を主成分とするペーストは、他にガラスフリット、溶剤とエチルセルロース等のバインダーを混合して構成される。第二の金属を主成分とするペーストと第三の金属を主成分とするペーストには同じガラスフリット、溶剤、バインダーを使用することが望ましい。これにより２つのペーストはその金属部分以外は同時に反応することになり、第二の金属と第三の金属はさらに合金化しやすくなる。これによって重なり部での剥離の問題を有効に解決できるようになる。
【００２６】
なお、本発明は上記実施形態に限定されるものではなく、本発明の範囲内で多くの修正および変更を加えることができる。例えば２回目の焼成によって形成される集電部５のアルミニウムからなる第二の金属を主成分とするペーストと出力取出部６の銀からなる第三の金属を主成分とするペーストとを塗布する順番はどちらが先でも構わない。また、ペーストを塗布した後の乾燥は、次のペーストを塗布するときに印刷機の作業テーブルやスクリーンに前のペーストが付着するといった問題がなければ省略してもよい。
【００２７】
第１の金属および第３の金属としては、白金や金を用いることもできる。
【００２８】
【発明の効果】
以上のように、本発明に係る太陽電池素子の形成方法によれば、半導体基板１の一主面側に表面電極となる第一の金属を主成分とするペーストを塗布して１回目の焼成を行った後、他の主面側に裏面電極の集電部となる第二の金属を主成分とするペーストを塗布するとともに、裏面電極の出力取出部となる第三の金属を主成分とするペーストを塗布して２回目の焼成を行うことから、集電部の焼成時に揮発するバインダーや溶剤によって表面電極の下の半導体基板の表面が汚染されたり、第一の金属の焼結が阻害されるといった問題は発生せず、表面電極の剥離の問題を有効に回避できる。
【００２９】
また集電部のアルミニウムからなる第二の金属を主成分とするペーストと出力取出部の銀からなる第三の金属を主成分とするペーストを同時に焼成するため、両者の重なり部では第二の金属と第三の金属の合金が形成されるため、この重なり部での剥離の問題は発生しない。
【００３０】
本発明の形成方法により得た太陽電池素子は、特に強い電極強度を必要とする、直列数の多い太陽電池モジュールに使用すれば更にその効果を有効に発揮する。
【図面の簡単な説明】
【図１】太陽電池素子の構造を説明する図である。
【図２】太陽電池素子の表面電極構造を説明する図である。
【図３】太陽電池素子の裏面電極構造を説明する図である。
【符号の説明】
１・・・半導体基板、２・・・拡散層、３・・・反射防止膜、４・・・表面電極、５・・・集電部、６・・・出力取出部、７・・・高濃度Ｐ型拡散層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a solar cell element, and more particularly to a method for forming a solar cell element in which a front electrode and a back electrode are formed by baking a metal paste.
[0002]
2. Description of the Related Art
FIG. 1 shows a conventional solar cell element. For example, an N-type impurity is diffused to a predetermined depth over the entire surface near the surface of the P-type semiconductor substrate 1 to provide an N-type diffusion layer 2, and an anti-reflection film 3 made of a silicon nitride film or the like is provided on the surface of the semiconductor substrate 1. In addition, the front surface electrode 4 is provided on the front surface, and the back surface electrodes 5 and 6 composed of the current collecting portion 5 made of aluminum or the like and the output extraction portion 6 made of silver or the like are provided on the back surface. On the back surface of the semiconductor substrate 1, a high-concentration P-type diffusion layer 7 is formed.
[0003]
In order to form the front electrode 4 and the back electrodes 5 and 6 of these solar cell elements, a paste mainly composed of a second metal made of aluminum is applied to most of the semiconductor substrate 1 except for a part of the back surface. After drying, a paste mainly composed of a third metal made of silver is applied so as to cover a portion where the paste mainly containing the second metal was not applied and a peripheral portion thereof, and then dried. Finally, a paste mainly composed of a first metal made of silver is applied to the surface of the semiconductor substrate 1 and dried, and a paste mainly composed of a first metal and a second metal are mainly composed. A method of simultaneously firing a paste and a paste containing a third metal as a main component, that is, a simultaneous firing method has been conventionally used (for example, see Patent Document 1).
[0004]
Further, a paste mainly composed of the second metal made of aluminum is applied to most of the back surface of the semiconductor substrate 1 except for a part thereof and dried, and then the paste mainly composed of the second metal is applied. A paste mainly composed of a third metal made of silver is applied so as to cover the unprocessed portion and the peripheral portion thereof, dried and baked for the first time, and then the surface of the semiconductor substrate 1 is made of silver. There is also a method in which a paste containing a first metal as a main component is applied, dried, and fired a second time (for example, see Patent Document 1).
[0005]
Further, a paste mainly composed of a second metal made of aluminum is applied to most of the semiconductor substrate 1 except for a part of the back surface, dried and baked for the first time. After applying a paste composed mainly of a third metal composed of silver so as to cover a part where the paste composed mainly of the third metal was not applied and its peripheral part and drying it, the surface of the semiconductor substrate 1 is composed of silver There is also a method in which a paste containing a first metal as a main component is applied, dried, and fired a second time (for example, see Patent Document 1).
[0006]
As a result, a current collecting portion 5 and an output extraction portion 6 having good solder wettability are formed on the back surface of the semiconductor substrate 1, and a high concentration P-type diffusion layer is formed on the semiconductor substrate 1 below the current collecting portion 5. 7 is formed.
[0007]
After that, solder (not shown) is applied on the surface electrode 4 and the output extraction portion 6 of the back electrode, and inner leads for connecting the solar cell elements in series or in parallel are connected.
[0008]
However, according to these methods, there was a problem that the surface electrode 4 was peeled off at the time of formation or later. That is, as can be seen from FIGS. 2 and 3, the area of the current collector 5 is larger than that of the surface electrode 4 and the output extraction section 6, and the amount of the paste used is large. And the like, the binder and the like are mixed, so that a solvent or a binder component volatilized when the current collector 5 is baked is scattered, thereby contaminating the surface of the semiconductor substrate 1 or inhibiting sintering of the surface electrode 4. Therefore, it is considered that this problem of peeling occurs. FIG. 2 shows a structure of a front electrode of a general solar cell element, and FIG. 3 shows a structure of a back electrode.
[0009]
As a method of solving this problem, a method of forming the current collector 5 of the back electrode, cleaning the surface of the semiconductor substrate 1, and then forming the front electrode 4 is considered. However, when this method is performed, the number of steps increases, which is not suitable for manufacturing.
[0010]
Further, a paste mainly composed of a first metal made of silver is applied to the surface of the semiconductor substrate 1 and baked for the first time, and a paste mainly composed of a second metal made of aluminum is applied to the back surface of the semiconductor substrate 1. After the second baking is performed by applying to most of the second metal, a second portion made of silver is formed so as to cover the portion where the paste containing the second metal as a main component is not applied and the peripheral portion thereof. There is also a method of applying a paste mainly composed of three metals and performing the third baking (for example, see Patent Document 2). According to this method, since the surface electrode 4 is formed before the current collector 5 is formed, the above-described problem of separation does not occur.
[0011]
However, according to this method, after the surface electrode 4 is formed, the current collecting part 5 is formed, and then the output extraction part 6 is formed. In some cases, a problem of deterioration in output characteristics occurs. In order to avoid this problem, if the firing temperature is reduced or the time is shortened, a problem may occur in that separation occurs between the current collecting portion 5 and the output extracting portion 6 of the back electrode. .
[0012]
The present invention has been made in view of such problems of the related art, and it is an object of the present invention to provide a method for forming a solar cell element having good output characteristics while preventing the occurrence of electrode peeling. .
[0013]
[Patent Document 1]
JP 10-335267 A [Patent Document 2]
JP 2000-188409 A
[Means for Solving the Problems]
In order to achieve the above object, in a method for forming a solar cell element according to the present invention, a semiconductor material having one conductivity type is diffused with a semiconductor impurity of a reverse conductivity type on one main surface side, and a first metal is used as a main component. Forming a front surface electrode, and collecting, on the other main surface side, a current collector mainly composed of a second metal and an output extraction mainly composed of a third metal having better solder wettability than the second metal. In a method for forming a solar cell element for forming a back electrode composed of a part and a paste comprising a first metal as a main component serving as the front electrode on one principal surface side of the semiconductor substrate, a first firing is performed. After that, a paste containing a second metal as a main component serving as a current collecting portion of the back electrode is applied to the other main surface side, and a paste containing a third metal as a main component serving as the output extraction portion is applied. And performing the second baking.
[0015]
In the method for forming a solar cell element, the first metal and the third metal are preferably made of silver.
[0016]
In the method for forming a solar cell element, it is preferable that the semiconductor substrate is made of silicon, and the paste containing the third metal as a main component contains aluminum.
[0017]
In the method for forming a solar cell element, the second metal is preferably made of aluminum.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
The structure of the solar cell element according to the present invention is basically the same as the conventional solar cell element. That is, for example, an N-type impurity is diffused to a certain depth over the entire surface near the surface of the P-type semiconductor substrate 1 to provide an N-type diffusion layer 2, and the anti-reflection film 3 made of a silicon nitride film or the like is provided on the surface of the semiconductor substrate 1. And a front surface electrode 4 is provided on the front surface, and a back surface electrode composed of a current collecting portion 5 made of aluminum or the like and an output extraction portion 6 made of silver or the like is provided on the back surface. On the back surface of the semiconductor substrate 1, a high-concentration P-type diffusion layer 7 is formed.
[0019]
In such a solar cell element, for example, a P-type semiconductor substrate 1 is heat-treated in an N-type impurity atmosphere to diffuse an N-type impurity to a certain depth over the entire surface region to form an N-type diffusion layer 2. After forming the antireflection film 3 by the CVD method or the like to separate the diffusion layer 2, the front surface electrode 4 and the back surface electrode composed of the current collecting portion 5 and the electrode extraction portion 6 are formed. 5, a high-concentration P-type diffusion layer 7 is formed in the semiconductor substrate 1 below.
[0020]
The above-mentioned surface electrode 4, current collecting part 5, and electrode extraction part 6 are formed as follows. That is, the surface of the semiconductor substrate 1 is coated with a paste mainly composed of, for example, a first metal made of silver, which becomes the surface electrode 4, and is baked at about 700 to 800 ° C. for about 1 to 30 minutes. If the sintering temperature at this time is 700 ° C. or less or the sintering time is 1 minute or less, the contact resistance of the surface electrode 4 with the semiconductor substrate 1 cannot be sufficiently reduced, and the characteristics of the solar cell element deteriorate. May be caused. If the firing temperature is 800 ° C. or higher or the firing time is 30 minutes or longer, the diffusion of the impurities in the diffusion layer 2 is diffused again, and the bonding becomes deeper. There is a possibility that problems such as destruction may occur.
[0021]
Next, on the back surface of the semiconductor substrate 1, a paste mainly composed of a second metal made of aluminum serving as a current collecting part 5 is applied, and a third metal made of, for example, silver serving as an output extracting part 6 is used as a main component. Is applied, and the second baking is performed at about 650 to 780 ° C. for about 0.5 to 20 minutes. If the firing temperature at this time is 650 ° C. or less, or the firing time is 0.5 minute or less, silver and aluminum do not sinter sufficiently and cause peeling, or the contact resistance is sufficiently reduced. Problems may occur. In addition, aluminum may not be sufficiently diffused into the semiconductor substrate 1 and a problem such as a decrease in output characteristics may occur. Conversely, if the baking temperature is 780 ° C. or more, or the baking time is 20 minutes or more, the impurities in the diffusion layer 2 are diffused again as described above, so that the junction is deepened or the surface electrode 4 is diffused. There is a possibility that a problem such as breaking of the junction of the layer 2 may occur.
[0022]
According to this method, the first metal made of silver of the surface electrode 4 is sintered by the first firing. Therefore, even if a second metal made of aluminum is applied to most of the back surface of the semiconductor substrate and then fired, the surface of the semiconductor substrate below the surface electrode is contaminated by a binder or a solvent volatilized at that time, or the first metal is contaminated. The problem that the sintering of the metal does not occur does not occur, and the problem of peeling of the surface electrode can be effectively avoided.
[0023]
Then, after that, the paste mainly composed of the second metal made of aluminum of the current collecting part 5 and the paste mainly composed of the third metal made of silver of the output extraction part 6 are simultaneously fired. In this case, since the alloy of the second metal and the third metal is formed, the problem of separation at the overlapping portion does not occur.
[0024]
It is desirable that the paste mainly composed of the third metal made of silver, which is applied as the output extraction section 6, contains aluminum. As a result, the second metal and the third metal are more easily alloyed, and the problem of peeling can be avoided even when the temperature for the second baking is reduced or the time is shortened.
[0025]
Such a paste containing a metal as a main component is formed by mixing a glass frit, a solvent, and a binder such as ethyl cellulose. It is desirable to use the same glass frit, solvent, and binder for the paste containing the second metal as the main component and the paste containing the third metal as the main component. As a result, the two pastes react simultaneously except for the metal portion, and the second metal and the third metal are more easily alloyed. As a result, the problem of peeling at the overlapping portion can be effectively solved.
[0026]
The present invention is not limited to the above embodiment, and many modifications and changes can be made within the scope of the present invention. For example, a paste mainly composed of a second metal made of aluminum of the current collecting portion 5 and a paste mainly composed of a third metal made of silver of the output extraction portion 6 formed by the second baking are applied. The order does not matter. The drying after the application of the paste may be omitted if there is no problem that the previous paste adheres to the work table or the screen of the printing press when the next paste is applied.
[0027]
As the first metal and the third metal, platinum and gold can also be used.
[0028]
【The invention's effect】
As described above, according to the method for forming a solar cell element according to the present invention, the first baking is performed by applying a paste containing a first metal as a main component to be a surface electrode on one main surface side of the semiconductor substrate 1. After that, while applying a paste containing a second metal as a main component serving as a current collecting portion of the back electrode to the other main surface side, a third metal serving as an output extracting portion of the back electrode as a main component The paste to be applied and baking for the second time, the surface of the semiconductor substrate under the surface electrode is contaminated by a binder or a solvent volatilized during baking of the current collector, or sintering of the first metal is hindered. Such a problem does not occur, and the problem of peeling of the surface electrode can be effectively avoided.
[0029]
In addition, since the paste mainly composed of the second metal made of aluminum of the current collecting portion and the paste mainly composed of the third metal made of silver of the output extraction portion are simultaneously baked, the second portion is overlapped in both portions. Since the alloy of the metal and the third metal is formed, the problem of separation at the overlapping portion does not occur.
[0030]
The solar cell element obtained by the forming method of the present invention exhibits its effect more effectively when used in a solar cell module requiring a particularly high electrode strength and having a large number of series.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the structure of a solar cell element.
FIG. 2 is a diagram illustrating a surface electrode structure of a solar cell element.
FIG. 3 is a diagram illustrating a back electrode structure of a solar cell element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Diffusion layer, 3 ... Anti-reflection film, 4 ... Surface electrode, 5 ... Current collecting part, 6 ... Output extraction part, 7 ... High Concentration P-type diffusion layer

Claims (4)

一導電型を呈する半導体基板の一主面側に逆導電型半導体不純物を拡散するとともに、第一の金属を主成分とする表面電極を形成し、他の主面側に第二の金属を主成分とする集電部とこの第二の金属よりも半田濡れ性のよい第三の金属を主成分とする出力取出部とから成る裏面電極を形成する太陽電池素子の形成方法において、前記半導体基板の一主面側に前記表面電極となる第一の金属を主成分とするペーストを塗布して１回目の焼成を行った後、他の主面側に前記裏面電極の集電部となる第二の金属を主成分とするペーストを塗布するとともに、前記出力取出部となる第三の金属を主成分とするペーストを塗布して２回目の焼成を行うことを特徴とする太陽電池素子の形成方法。On the one main surface side of the semiconductor substrate having one conductivity type, the opposite conductivity type semiconductor impurity is diffused, and a surface electrode mainly composed of the first metal is formed, and the second metal is mainly formed on the other main surface side. A method of forming a back electrode comprising a current collecting portion as a component and an output extracting portion mainly composed of a third metal having better solder wettability than the second metal; After applying a paste containing a first metal as a main component to be the surface electrode as a main component on the one main surface side and performing the first baking, the second main surface side serving as a current collector of the back electrode is formed. Forming a solar cell element by applying a paste mainly composed of a second metal and applying a paste mainly composed of a third metal serving as the output extraction portion and performing second baking; Method. 前記第一の金属と前記第三の金属が銀からなることを特徴とする請求項１に記載の太陽電池素子の形成方法。The method according to claim 1, wherein the first metal and the third metal are made of silver. 前記半導体基板がシリコンからなり、前記第三の金属を主成分とするペーストにアルミニウムを含有することを特徴とする請求項１または２に記載の太陽電池素子の形成方法。3. The method according to claim 1, wherein the semiconductor substrate is made of silicon, and the paste containing the third metal as a main component contains aluminum. 4. 前記第二の金属がアルミニウムからなることを特徴とする請求項１ないし３のいずれかに記載の太陽電池素子の形成方法。4. The method according to claim 1, wherein the second metal is made of aluminum.
JP2002342878A 2002-11-26 2002-11-26 Method of forming solar cell element Pending JP2004179334A (en)

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JP2008311662A (en) * 2007-06-13 2008-12-25 Schott Solar Gmbh Semiconductor element, and metal-semiconductor contact manufacturing method
KR20200023301A (en) * 2017-06-26 2020-03-04 신에쓰 가가꾸 고교 가부시끼가이샤 High efficiency back electrode solar cell and its manufacturing method

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JPH08148447A (en) * 1994-11-25 1996-06-07 Murata Mfg Co Ltd Conductive paste and solar battery provided with electrode using conductive paste
JPH10335267A (en) * 1997-05-30 1998-12-18 Mitsubishi Electric Corp Manufacture of semiconductor device
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JP2003142711A (en) * 2001-11-06 2003-05-16 Sony Corp Method for manufacturing integrated solar battery

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Publication number Priority date Publication date Assignee Title
JPH06209115A (en) * 1993-01-12 1994-07-26 Sanyo Electric Co Ltd Solder part forming method of solar cell
JPH08148447A (en) * 1994-11-25 1996-06-07 Murata Mfg Co Ltd Conductive paste and solar battery provided with electrode using conductive paste
JPH10335267A (en) * 1997-05-30 1998-12-18 Mitsubishi Electric Corp Manufacture of semiconductor device
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JP2008311662A (en) * 2007-06-13 2008-12-25 Schott Solar Gmbh Semiconductor element, and metal-semiconductor contact manufacturing method
US8610289B2 (en) 2007-06-13 2013-12-17 Schott Solar Ag Semiconductor component and method for producing a metal-semiconductor contact
KR20200023301A (en) * 2017-06-26 2020-03-04 신에쓰 가가꾸 고교 가부시끼가이샤 High efficiency back electrode solar cell and its manufacturing method
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