JP2015062251A - Solar cell and method for manufacturing the same - Google Patents

Solar cell and method for manufacturing the same Download PDF

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JP2015062251A
JP2015062251A JP2014241082A JP2014241082A JP2015062251A JP 2015062251 A JP2015062251 A JP 2015062251A JP 2014241082 A JP2014241082 A JP 2014241082A JP 2014241082 A JP2014241082 A JP 2014241082A JP 2015062251 A JP2015062251 A JP 2015062251A
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electrode
passivation film
solar cell
layer
paste
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村上　貴志
Takashi Murakami
貴志 村上
渡部　武紀
Takenori Watabe
武紀 渡部
大塚　寛之
Hiroyuki Otsuka
寛之 大塚
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Shin Etsu Chemical Co Ltd
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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
    • Y02E10/546—Polycrystalline silicon PV 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

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and highly efficient solar cell having an electrode that has good electric contact with a silicon substrate and suppresses wiring resistance.SOLUTION: A method for manufacturing a solar cell is provided, including steps of: applying an electrode paste for forming a first electrode comprising conductive particles and glass frit on an emitter layer of a first major surface of a crystalline silicon substrate; forming a passivation film thereon; further applying an electrode paste for forming a second electrode comprising conductive particles and glass frit on the passivation film to partially overlap the first electrode; subjecting the substrate to an electrode firing heat treatment so as to form first and second electrodes, as well as to form a passivation film penetration layer that electrically conducts between the first and second electrodes by inducing a fire-through process in the passivation layer by the electrode pastes in the overlapped part of the first electrode and the second electrode, while leaving the passivation film without penetration by the electrode paste just below the electrode paste of the second electrode in a region where the second electrode does not overlap the first electrode.

Description

本発明は、安価で高効率な太陽電池、及びその製造方法に関する。   The present invention relates to an inexpensive and highly efficient solar cell and a manufacturing method thereof.

単結晶や多結晶シリコン基板を用いた一般的な量産型太陽電池の外観を図１（Ｂ）に示す。
ＢやＧａなどのドーパントを添加したｐ型シリコン基板１０１の受光面側に、ｎ型の導電型を付与するＰやＳｂなどのドーパントが拡散され、エミッタ層１０２が形成されている。
前記エミッタ層１０２の上には、パッシベーション膜１０３が形成されている。前記パッシベーション膜１０３は反射防止膜としても機能する。パッシベーション膜１０３は化学気相堆積（ＣＶＤ）などで形成されるＳｉＮｘ膜などが広く用いられている。前記パッシベーション膜の重要な機能として、シリコン表面の終端化がある。結晶内部のシリコン原子は隣接する原子同士で共有結合し安定な状態にある。しかし、原子配列の末端である表面では結合すべき隣接原子が不在となることで、未結合手又はダングリングボンドといわれる不安定なエネルギー準位が出現する。ダングリングボンドは電気的に活性であるためシリコン内部で光生成された電荷を捕らえて消滅させてしまい、太陽電池の特性が損なわれる。そこで太陽電池では何らかの表面終端化処理又は電界を形成して光生成キャリアがダングリングボンドに捕獲されないようにする処理が施してある。ＣＶＤで形成されるＳｉＮｘ膜が広く用いられているのは、光学的特性がシリコン太陽電池に適していることに加え、膜自体が正の固定電荷をもち、更にダングリングボンドの終端効果のある水素を多く含んでおり、高いパッシベーション効果を有するからである。 FIG. 1B shows the appearance of a general mass-produced solar cell using a single crystal or polycrystalline silicon substrate.
On the light-receiving surface side of the p-type silicon substrate 101 to which a dopant such as B or Ga is added, a dopant such as P or Sb imparting n-type conductivity is diffused to form an emitter layer 102.
A passivation film 103 is formed on the emitter layer 102. The passivation film 103 also functions as an antireflection film. As the passivation film 103, a SiNx film formed by chemical vapor deposition (CVD) or the like is widely used. An important function of the passivation film is termination of the silicon surface. The silicon atoms inside the crystal are in a stable state due to covalent bonding between adjacent atoms. However, an unstable energy level called a dangling bond or a dangling bond appears due to the absence of adjacent atoms to be bonded on the surface which is the terminal of the atomic arrangement. Since dangling bonds are electrically active, they capture and extinguish charges generated in the silicon, thereby deteriorating the characteristics of the solar cell. Therefore, the solar cell is subjected to some surface termination treatment or treatment to form an electric field so that photogenerated carriers are not captured by dangling bonds. The SiNx film formed by CVD is widely used because its optical characteristics are suitable for silicon solar cells, the film itself has a positive fixed charge, and has a dangling bond termination effect. This is because it contains a large amount of hydrogen and has a high passivation effect.

前記パッシベーション膜１０３の上には、光生成された電荷をシリコン基板１０１から外部に取り出す、数百〜数十μｍ幅の取出電極１０４が多数形成され、また、前記取出電極１０４で集められた電荷を集約し、太陽電池セルを連絡するための電極として数ｍｍ幅の集電電極１０５が数本形成されている。   A large number of extraction electrodes 104 with a width of several hundreds to several tens of μm are formed on the passivation film 103 to extract photogenerated charges from the silicon substrate 101 to the outside, and the charges collected by the extraction electrodes 104 are formed. Several collecting electrodes 105 having a width of several millimeters are formed as electrodes for concentrating and connecting solar cells.

これら電極は、コストの点からＡｇなどの金属微粒子とガラスフリットと有機バインダー等を混ぜた電極ペーストが用いられ、例えば図５（Ｄ）に示したパターンのスクリーン版を用いて印刷され、乾燥された後、数百〜８５０℃程度で電極焼成熱処理を行うことで、電極直下部にパッシベーション膜貫通層１０８が形成され、基板１０１と電極１０４が電気的に接続される方法（いわゆるファイヤースルー法）が広く用いられている。
なお、本発明において、前記パッシベーション膜貫通層とは、電気的に導通している部分と前記パッシベーション膜が残存している部分とが混在している層のことを言う。 For these electrodes, an electrode paste in which metal fine particles such as Ag, glass frit, and an organic binder are mixed is used from the viewpoint of cost. For example, the electrodes are printed and dried using a screen plate having the pattern shown in FIG. After that, the electrode firing heat treatment is performed at about several hundred to 850 ° C. to form the passivation film penetrating layer 108 immediately below the electrode, and the substrate 101 and the electrode 104 are electrically connected (so-called fire-through method). Is widely used.
In the present invention, the passivation film penetrating layer refers to a layer in which an electrically conductive portion and a portion where the passivation film remains are mixed.

非受光面側には、受光面側電極とは逆極性となる裏面電極１０７が、ＡｌやＡｇなどの金属微粒子を有機バインダーに混ぜた金属ペーストが用いられ、例えば略全面を覆うパターンのスクリーン版などを用いて印刷され、乾燥された後、数百〜８５０℃程度での電極焼成熱処理により形成されている。
また、シリコン基板１０１と裏面電極１０７の間には、裏面側で発生した電荷をより効率良く外部へ取り出すために、基板と同じｐ型の導電型を付与するＡｌやＢ又はＧａなどのドーパントが高濃度に含まれ、電極焼成熱処理により電界層１０６が形成されている。 On the non-light-receiving surface side, a back electrode 107 having a polarity opposite to that of the light-receiving surface side electrode is used, and a metal paste in which metal fine particles such as Al and Ag are mixed with an organic binder is used. After being printed and dried using a method such as the above, it is formed by an electrode firing heat treatment at about several hundred to 850 ° C.
In addition, a dopant such as Al, B, or Ga that imparts the same p-type conductivity as that of the substrate is provided between the silicon substrate 101 and the back electrode 107 in order to more efficiently extract the charge generated on the back side to the outside. The electric field layer 106 is included by high-concentration electrode heat treatment.

ここで、前記一般的な量産型太陽電池の電極焼成熱処理前の外観を図１（Ａ）に示す。電極焼成熱処理前の時点では、受光面側取出電極１０４直下にはパッシベーション膜貫通層１０８が形成されておらず、また裏面電極１０７直下には電界層１０６は形成されていない。   Here, the external appearance of the general mass-produced solar cell before the electrode firing heat treatment is shown in FIG. Prior to the electrode firing heat treatment, the passivation film penetrating layer 108 is not formed immediately below the light receiving surface side extraction electrode 104, and the electric field layer 106 is not formed immediately below the back surface electrode 107.

上記従来法で使用する電極ペーストは、電極焼成熱処理によって電極直下のパッシベーション膜を貫通させ、電極をシリコン基板に接触させるため、比較的高い割合でガラスフリットを含有している。このため、電極とシリコン基板の良好な電気的接触が得られる反面、シリコン基板から取り出された電荷の伝導を担う金属粒子の含有割合を低くせざるを得ず、結果として太陽電池の出力を低下させてしまうという問題があった。（単層電極の場合の問題点）
この間題に対し、本発明者らは、先に前記パッシベーション膜を貫通してシリコン基板と接触させるための電極と、電気伝導を担うための低抵抗電極とを重ね合わせ、高アスペクト比を有すると共に、断線等の不具合が起こりにくい多層電極の形成方法を提案した（国際公開第２００８／０２６４１５号パンフレット：特許文献１）。 The electrode paste used in the conventional method contains a glass frit at a relatively high rate in order to penetrate the passivation film directly under the electrode by electrode baking heat treatment and bring the electrode into contact with the silicon substrate. For this reason, good electrical contact between the electrode and the silicon substrate can be obtained, but the content ratio of the metal particles responsible for the conduction of electric charges taken out from the silicon substrate has to be lowered, resulting in a decrease in the output of the solar cell. There was a problem of letting it go. (Problems with single-layer electrodes)
In response to this problem, the inventors previously overlapped an electrode for penetrating the passivation film and contacting the silicon substrate with a low resistance electrode for carrying electric conduction, and has a high aspect ratio. In addition, a method for forming a multilayer electrode in which defects such as disconnection hardly occur has been proposed (International Publication No. 2008/026415 Pamphlet: Patent Document 1).

前記多層電極の形成方法では、シリコン基板と接触する下部電極は、少なくとも銀とガラスフリットとを含有し、この上に配置される上部電極は、銀の総含有割合が高く（７５ｗｔ％以上９５ｗｔ％以下）、かつ銀の総含有量に対する平均粒径４μｍ以上８μｍ以下の銀粒子の含有割合が、前記下部電極中の含有割合より高い導電性ペーストを焼成したことが特徴となっている。   In the method for forming a multilayer electrode, the lower electrode in contact with the silicon substrate contains at least silver and glass frit, and the upper electrode disposed thereon has a high total silver content (75 wt% to 95 wt%). And a conductive paste having an average content of silver particles having an average particle size of 4 μm or more and 8 μm or less with respect to the total content of silver is higher than the content in the lower electrode.

前記一般的な太陽電池に対し、前記多層電極形成方法を適用した太陽電池の外観の一例を図２（Ａ）、（Ｂ）に示す。電極焼成熱処理前の外観が図２（Ａ）、電極焼成熱処理後の外観が図２（Ｂ）である。
その製造方法は、前記パッシベーション膜の形成までは前記一般的な太楊電池と同様に行い、前記パッシベーション膜の上に、この例では下部電極として第１電極２０４を形成し、この上に上部電極として第２電極２０５を形成している。その後、電極焼成熱処理によって、第１電極２０４直下にパッシベーション膜貫通層２０８を形成し、裏面電極２０７直下に電界層２０６を形成している。 An example of the appearance of a solar cell in which the multilayer electrode forming method is applied to the general solar cell is shown in FIGS. FIG. 2A shows the appearance before the electrode firing heat treatment, and FIG. 2B shows the appearance after the electrode firing heat treatment.
The manufacturing method is the same as that of the general solar battery until the formation of the passivation film, and the first electrode 204 is formed on the passivation film as a lower electrode in this example, and the upper electrode is formed thereon. As a result, the second electrode 205 is formed. Thereafter, a passivation film penetrating layer 208 is formed immediately below the first electrode 204 and an electric field layer 206 is formed directly below the back electrode 207 by electrode firing heat treatment.

前記多層電極形成方法の問題点は、配線抵抗が低い電極を形成するため、第１電極の上に第２電極を少なくとも１回、望ましくは複数回重ね合わせて形成する必要があり、その都度工程数が増加してしまうことである。（多層電極形成方法の問題点）
前記多層電極形成方法において、電極形成工程数を最低限即ち第１電極及び第２電極を各１回に留めて、配線抵抗が低い電極を形成するには、前記第１電極及び第２電極に含まれるガラスフリット含有量を最小限に抑え、銀粒子含有量を極力増やす必要がある。 The problem with the multilayer electrode forming method is that, in order to form an electrode with low wiring resistance, it is necessary to form the second electrode on the first electrode by overlapping at least once, preferably a plurality of times. The number will increase. (Problems of the multilayer electrode formation method)
In the multilayer electrode forming method, in order to form an electrode with a low wiring resistance by keeping the number of electrode forming steps to a minimum, that is, each time the first electrode and the second electrode are once, the first electrode and the second electrode It is necessary to minimize the glass frit content contained and increase the silver particle content as much as possible.

一方で前記電極ペーストに含まれるガラスフリットには、次の特徴があることが知られている。
・電極焼成熱処理によってパッシベーション膜と反応し、パッシベーション膜を分解・貫通することで、電極ペーストに含まれる金属粒子等が基板と電気的に接触する。（いわゆるファイヤースルー機能）
・電極焼成熱処理によってパッシベーション膜と反応せず残ったガラスフリットが、基板と電極の接着強度を高める。（いわゆる接着剤機能）
これらガラスフリットの機能を十分に発現させるため、前記電極ペーストに含まれるガラスフリット量を増やし過ぎると、ファイヤースルー機能及び接着剤機能は上昇するが、電極の配線抵抗が上昇し、またパッシペーション膜と反応せずに残るガラスフリツ卜が増加して、基板と電極の界面や電極表面にガラス膜を形成するなどして、接触抵抗が上昇したり、電極から外部への配線を接続する際の半田濡れ性を悪化させるなどの不具合がある。（ガラスフリットを増やし過ぎた場合の不具合） On the other hand, it is known that the glass frit contained in the electrode paste has the following characteristics.
-It reacts with the passivation film by the electrode baking heat treatment, and decomposes and penetrates the passivation film, so that metal particles contained in the electrode paste are in electrical contact with the substrate. (So-called fire-through function)
-The glass frit remaining without reacting with the passivation film by the electrode firing heat treatment increases the adhesion strength between the substrate and the electrode. (So-called adhesive function)
In order to fully develop the function of these glass frit, if the amount of glass frit contained in the electrode paste is excessively increased, the fire-through function and the adhesive function are increased, but the wiring resistance of the electrode is increased, and the passivation film is also increased. The amount of glass flakes that remain without reacting with the solder increases, and a glass film is formed on the interface between the substrate and the electrode or on the surface of the electrode to increase contact resistance or solder when connecting wiring from the electrode to the outside. There are problems such as worsening wettability. (Problems caused by excessive glass frit)

この反対に、前記電極ペーストに含まれるガラスフリットを減らし過ぎると、電極の配線抵抗は低下するが、短時間の電極焼成熱処理ではファイヤースルー機能が悪化し、基板と電極の接触抵抗が上昇し、また接着剤機能も悪化し、電極の接着強度が低下するなどの不具合がある。（ガラスフリットを減らし過ぎた場合の不具合）   On the contrary, if the glass frit contained in the electrode paste is reduced too much, the wiring resistance of the electrode is lowered, but the fire-through function is deteriorated by a short-time electrode firing heat treatment, and the contact resistance between the substrate and the electrode is increased, In addition, the adhesive function also deteriorates, and there are problems such as a decrease in the adhesive strength of the electrode. (Problems when the glass frit is reduced too much)

これに対し、電極焼成熱処理を高温化又は長時間化すると、基板のバルクライフタイムが悪化したり、前記パッシベーション膜によるパッシベーション性が低下したりして、開放電圧や短絡電流が低下するなどの不具合がある。（電極焼成熱処理を高温化又は長時間化させた場合の不具合）   On the other hand, when the electrode firing heat treatment is heated to a high temperature or for a long time, the bulk lifetime of the substrate is deteriorated, the passivation property due to the passivation film is lowered, and the open circuit voltage and the short circuit current are lowered. There is. (Problems when the electrode firing heat treatment is heated or prolonged)

実際には、これらの不具合がなるべく起こらないように、前記電極ペーストに含まれるガラスフリットの種類と添加量、そして電極焼成熱処理条件等を調整して、配線抵抗と接触抵抗を低く抑え、かつ基板と電極の接着強度を一定以上に保ち、かつ開放電圧及び短絡電流の低下を抑えるようにしている。   Actually, in order to prevent these problems as much as possible, the type and amount of glass frit contained in the electrode paste and the electrode firing heat treatment conditions are adjusted to keep the wiring resistance and contact resistance low, and the substrate. In addition, the adhesive strength between the electrode and the electrode is kept above a certain level, and the decrease in the open circuit voltage and the short circuit current is suppressed.

このため、通常は前記電極ペーストには前記パッシベーション膜を貫通させるために必要な量より多くガラスフリットが含まれており、電極焼成熱処理によって前記パッシベーション膜と反応するガラスフリットは、実際に電極に含まれるガラスフリットのうち、前記パッシベーション膜近傍にある一部分のみである。
前記パッシベーション膜と電極ペーストに含まれるガラスフリットを効率良く反応させるには、電極と前記パッシベーション膜の接触面積を広げる必要がある。 For this reason, usually, the electrode paste contains more glass frit than is necessary for penetrating the passivation film, and the glass frit that reacts with the passivation film by the electrode baking heat treatment is actually included in the electrode. Of the glass frit to be produced, only a part in the vicinity of the passivation film is present.
In order to efficiently react the passivation film and the glass frit contained in the electrode paste, it is necessary to increase the contact area between the electrode and the passivation film.

国際公開第２００８／０２６４１５号パンフレットInternational Publication No. 2008/026415 Pamphlet

本発明は、上記事情に鑑みなされたもので、シリコン基板と電気的接触が良好で、かつ配線抵抗が抑制された電極を有する安価で高効率な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 an object of the present invention is to provide an inexpensive and highly efficient solar cell having an electrode with good electrical contact with a silicon substrate and suppressed wiring resistance.

上記課題を解決するため、本発明者らは太陽電池の電極形成方法について鋭意研究を重ねた結果、エミッタ層上に導電性粒子とガラスフリットを含有する第１電極を直接形成し、その上にパッシベーション膜を形成し、更にその上に第１電極と部分的に又は全体的に重なり合うように導電性粒子とガラスフリットを含有する第２電極を形成し、このように第１電極と第２電極とをパッシベーション膜を介して形成すると共に、ファイヤースルーによりこれら第１及び第２電極間のパッシベーション膜をパッシベーション膜貫通層として第１及び第２電極間を導通させることが、シリコン基板と電気的接触が良好で、かつ配線抵抗が抑制された電極を有する安価で高効率な太陽電池を提供する点で有効であり、従来法に比べ電極ペーストに含まれるガラスフリット量を更に減らすことが可能となり、配線抵抗を抑制することができる。また、工程は従来技術のパッシペーション膜形成法とスクリーン印刷法などの組み合わせにより実現可能であり、コスト削減に極めて有効であることを知見し、本発明をなすに至った。   In order to solve the above problems, the present inventors have conducted extensive research on a method for forming an electrode of a solar cell. As a result, the first electrode containing conductive particles and glass frit is directly formed on the emitter layer, and the first electrode is formed thereon. A passivation film is formed, and further, a second electrode containing conductive particles and glass frit is formed thereon so as to partially or entirely overlap with the first electrode, and thus the first electrode and the second electrode are formed. Are formed through a passivation film, and the first and second electrodes are electrically connected to each other by a through-hole, using the passivation film between the first and second electrodes as a passivation film penetrating layer. Is effective in providing an inexpensive and highly efficient solar cell having an electrode with good resistance and reduced wiring resistance, and is included in the electrode paste compared to the conventional method Furthermore it becomes possible to reduce the glass frit amount that, the wiring resistance can be suppressed. In addition, the present inventors have found that the process can be realized by a combination of a conventional passivation film forming method and a screen printing method, and is extremely effective for cost reduction, and has led to the present invention.

従って、本発明は、結晶シリコン基板の少なくとも第一主表面のエミッタ層上に導電性粒子とガラスフリットを含有する第１電極形成用電極ペーストを塗布し、その上にパッシベーション膜を形成し、更にパッシベーション膜上に第１電極と部分的に重なり合うように導電性粒子とガラスフリットを含有する第２電極形成用電極ペーストを塗布し、次いで電極焼成熱処理により第１及び第２電極を形成すると共に、前記第１電極及び第２電極の重なり合った部分の電極ペーストがこれら間のパッシベーション膜をそれぞれファイヤースルーすることにより前記第１及び第２電極間を導通するパッシベーション膜貫通層を形成すると共に、前記第２電極の第１電極とは重なり合わない部分の電極ペーストでその直下のパッシベーション膜を貫通させずに該パッシベーション膜を残すことを特徴とする太陽電池の製造方法を提供する。   Therefore, the present invention applies a first electrode forming electrode paste containing conductive particles and glass frit on the emitter layer of at least the first main surface of the crystalline silicon substrate, forms a passivation film thereon, and A second electrode forming electrode paste containing conductive particles and glass frit is applied on the passivation film so as to partially overlap the first electrode, and then the first and second electrodes are formed by electrode baking heat treatment, The electrode paste where the first electrode and the second electrode overlap each other passes through the passivation film between them to form a passivation film through layer that conducts between the first and second electrodes, and The part of electrode paste that does not overlap with the first electrode of the two electrodes penetrates the passivation film directly below To provide a method of manufacturing a solar cell characterized by leaving the passivation film without.

また、本発明は、結晶シリコン基板の少なくとも第一主表面のエミッタ層上に導電性粒子とガラスフリットを含有する第１電極形成用電極ペーストを塗布し、その上にパッシベーション膜を形成した後、電極焼成熱処理により第１電極を形成すると共に、前記電極ペーストをこの第１電極形成位置に対応するパッシベーション膜にファイヤースルーさせ、次に前記パッシベーション膜上に第１電極と部分的に重なり合うように導電性粒子とガラスフリットを含有する第２電極形成用電極ペーストを塗布し、次いで電極焼成熱処理により第２電極を形成すると共に、第２電極形成用電極ペーストがこの第２電極形成位置に対応するパッシベーション膜をファイヤースルーすることにより前記第１電極と重なり合った部分において前記第１及び第２電極間を導通するパッシベーション膜貫通層を形成すると共に、前記第１電極とは重なり合わない部分においてその直下のパッシベーション膜を貫通させずに該パッシベーション膜を残すことを特徴とする太陽電池の製造方法を提供する。
なお、これらの太陽電池の製造方法において、前記第１電極として取出電極のみのパターンで塗布し、前記第２電極として取出電極及び集電電極のパターンであって該取出電極のパターンが第１電極と重なり合うように塗布することが好ましく、また前記第１電極として略平行な複数本からなる点線状パターンを塗布し、前記第２電極の取出電極として略平行な複数本からなる直線状パターンを塗布し、前記第２電極の取出電極において第１電極と重なり合わず単層となる直下の前記パッシベーション膜を残すことが好ましい。 Further, in the present invention, after applying a first electrode forming electrode paste containing conductive particles and glass frit on the emitter layer of at least the first main surface of the crystalline silicon substrate, and forming a passivation film thereon, A first electrode is formed by an electrode baking heat treatment, and the electrode paste is fired through the passivation film corresponding to the first electrode formation position, and then conductive so as to partially overlap the first electrode on the passivation film. The second electrode forming electrode paste containing the conductive particles and the glass frit is applied, and then the second electrode is formed by electrode baking heat treatment, and the second electrode forming electrode paste corresponds to the second electrode forming position. The first and second electrodes are overlapped with the first electrode by fire-through the membrane. A method of manufacturing a solar cell, comprising: forming a passivation film penetrating layer that conducts between electrodes; and leaving the passivation film without penetrating the passivation film immediately below the first electrode in a portion that does not overlap with the first electrode I will provide a.
In these solar cell manufacturing methods, the first electrode is applied in a pattern of only an extraction electrode, and the second electrode is a pattern of an extraction electrode and a collector electrode. The pattern of the extraction electrode is the first electrode. It is preferable to apply so as to overlap with each other, and a plurality of substantially parallel dotted lines are applied as the first electrode, and a plurality of substantially parallel linear patterns are applied as the extraction electrodes of the second electrode. However, it is preferable to leave the passivation film immediately below which is a single layer without overlapping the first electrode in the extraction electrode of the second electrode.

更に、前記太陽電池の製造方法により製造された太陽電池であって、結晶シリコン基板の少なくとも第一主表面のエミッタ層上に直接形成された第１電極層と、この第１電極層を覆って前記エミッタ層上に形成されたパッシベーション膜と、このパッシベーション膜を介して前記第１電極層に部分的に重なり合って形成された第２電極層とを有し、前記第１及び第２電極層間の重なり合った部分のパッシベーション膜が第１及び第２電極層のファイヤースルーによってこれら第１及び第２電極層間を導通するパッシベーション膜貫通層として形成されてなり、前記第２電極の第１電極とは重なり合わず単層となった部分の直下に前記パッシベーション膜を有することを特徴とする太陽電池を提供する。
この場合、前記第１電極が取出電極のみからなり、前記第２電極が取出電極及び集電電極からなっており、第１電極及び第２電極の取出電極が重なり合っていることが好ましく、前記シリコン基板の第一主表面上において、前記第１電極が略平行な複数本からなる点線状パターンからなり、前記第２電極の取出電極が略平行な複数本からなる直線状パターンからなり、前記第２電極の取出電極において第１電極とは重なり合わず単層となる直下に前記パッシベーション膜を有することが好ましい。
また、前記第１電極と前記第２電極の組み合わせでなる電極が、太陽電池の受光面側に形成されていることが好ましい。前記パッシベーション膜は、酸化シリコン、窒化シリコン、炭化シリコン、酸化アルミニウム、アモルファスシリコン、微結晶シリコン、酸化チタンのいずれか又はその組み合わせから形成することができる。 Furthermore, a solar cell manufactured by the method for manufacturing a solar cell, the first electrode layer formed directly on the emitter layer on at least the first main surface of the crystalline silicon substrate, and covering the first electrode layer A passivation film formed on the emitter layer, and a second electrode layer formed so as to partially overlap the first electrode layer via the passivation film, and between the first and second electrode layers The overlapping portion of the passivation film is formed as a passivation film penetrating layer that conducts between the first and second electrode layers by fire-through of the first and second electrode layers, and overlaps the first electrode of the second electrode. Provided is a solar cell characterized in that the passivation film is provided directly under a portion that does not fit into a single layer.
In this case, it is preferable that the first electrode is composed only of an extraction electrode, the second electrode is composed of an extraction electrode and a collecting electrode, and the extraction electrodes of the first electrode and the second electrode overlap each other, and the silicon On the first main surface of the substrate, the first electrode comprises a plurality of substantially parallel dotted lines, the second electrode extraction electrode comprises a substantially parallel plurality of linear patterns, In the two-electrode extraction electrode, the passivation film is preferably provided immediately below the first electrode without overlapping with the first electrode.
Moreover, it is preferable that the electrode which consists of a combination of a said 1st electrode and a said 2nd electrode is formed in the light-receiving surface side of a solar cell. The passivation film can be formed of any one of silicon oxide, silicon nitride, silicon carbide, aluminum oxide, amorphous silicon, microcrystalline silicon, and titanium oxide, or a combination thereof.

本発明の多層電極構造とすることで、前記パッシベーション膜が前記第１電極層と第２電極層に挟まれるため、前記第１電極と第２電極のそれぞれの電極ペーストに含まれるガラスフリットによって上下から効率的にファイヤースルーが起き、第１電極と第２電極がパッシベーション膜貫通層を通して電気的に接続される。また、前記第１電極は前記エミッタ層上に直接形成されるため、従来法に比ベコンタク卜抵抗を更に低くすることができる。
このため、従来法に比べ電極ペーストに含まれるガラスフリット量を更に減らすことが可能となり、配線抵抗を抑制することができる。
また、工程は従来技術のパッシベーション膜形成法とスクリーン印刷法などの組み合わせにより実現可能であり、コスト削減に極めて有効である。 With the multilayer electrode structure of the present invention, since the passivation film is sandwiched between the first electrode layer and the second electrode layer, the glass frit contained in the respective electrode pastes of the first electrode and the second electrode is Thus, fire-through occurs efficiently, and the first electrode and the second electrode are electrically connected through the passivation film penetrating layer. Further, since the first electrode is formed directly on the emitter layer, the contact resistance can be further reduced as compared with the conventional method.
For this reason, it becomes possible to further reduce the amount of glass frit contained in the electrode paste as compared with the conventional method, and the wiring resistance can be suppressed.
Further, the process can be realized by a combination of a conventional passivation film forming method and a screen printing method, which is extremely effective for cost reduction.

従来の単層電極構造を有する太陽電池の斜視図で、（Ａ）は電極焼成熱処理前、（Ｂ）は電極焼成熱処理後の図である。It is a perspective view of the solar cell which has the conventional single layer electrode structure, (A) is before an electrode baking heat processing, (B) is a figure after an electrode baking heat processing. 従来の多層電極構造を有する太陽電池の斜視図で、（Ａ）は電極焼成熱処理前、（Ｂ）は電極焼成熱処理後の図である。It is a perspective view of the solar cell which has the conventional multilayer electrode structure, (A) is before an electrode baking heat processing, (B) is a figure after an electrode baking heat processing. 本発明の一実施例に係る多層電極構造を有する太陽電池の斜視図で、（Ａ）は電極焼成熱処理前、（Ｂ）は電極焼成熱処理後の図である。It is a perspective view of the solar cell which has the multilayer electrode structure which concerns on one Example of this invention, (A) is before an electrode baking heat processing, (B) is a figure after an electrode baking heat processing. 本発明の他の実施例に係る多層電極構造を有する太陽電池の斜視図で、（Ａ）は電極焼成熱処理前、（Ｂ）は電極焼成熱処理後の図である。It is a perspective view of the solar cell which has the multilayer electrode structure which concerns on the other Example of this invention, (A) is before electrode baking heat processing, (B) is a figure after electrode baking heat processing. （Ａ）〜（Ｄ）はそれぞれ電極形成に用いる印刷製版の例を示す平面図である。(A)-(D) are each a top view which shows the example of the printing plate making used for electrode formation. 本発明の別の実施例を示す多層電極構造を有する太陽電池の斜視図で、（Ａ）は電極焼成熱処理前、（Ｂ）は電極焼成熱処理後の図である。It is a perspective view of the solar cell which has a multilayer electrode structure which shows another Example of this invention, (A) is before an electrode baking heat processing, (B) is a figure after an electrode baking heat processing. 本発明の更に別の実施例を示す多層電極構造を有する太陽電池の斜視図で、（Ａ）は電極焼成熱処理前、（Ｂ）は電極焼成熱処理後の図である。It is a perspective view of the solar cell which has the multilayer electrode structure which shows another Example of this invention, (A) is before an electrode baking heat processing, (B) is a figure after an electrode baking heat processing. 実施例（条件３）と比較例（条件１、条件２）における接触抵抗と配線抵抗の相対値を示すグラフである。It is a graph which shows the relative value of the contact resistance and wiring resistance in an Example (condition 3) and a comparative example (condition 1, condition 2).

本発明に係る太陽電池は、上述したように、結晶シリコン基板の少なくとも第一主表面のエミッタ層上に直接形成された第１電極層と、この第１電極層を覆って前記エミッタ層上に形成されたパッシベーション膜と、このパッシベーション膜を介して前記第１電極層に少なくとも部分的に重なり合って形成された第２電極層とを有し、前記第１及び第２電極層間のパッシベーション膜が第１及び第２電極層のファイヤースルーによってこれら第１及び第２電極層間を導通するパッシベーション膜貫通層として形成されてなるものである。   As described above, the solar cell according to the present invention includes the first electrode layer directly formed on the emitter layer on at least the first main surface of the crystalline silicon substrate, and the first electrode layer covering the first electrode layer on the emitter layer. A passivation film formed, and a second electrode layer formed at least partially overlapping the first electrode layer via the passivation film, the passivation film between the first and second electrode layers being a first The first and second electrode layers are formed as a passivation film penetrating layer that conducts between the first and second electrode layers by fire-through of the first and second electrode layers.

以下、図３〜図７を参照して本発明の実施例を説明するが、本発明の太陽電池は図示の実施例に限られるものではない。
図３は、本発明による太陽電池の一実施例を示す。
本発明による太陽電池は、結晶シリコン基板３０１の少なくとも片面にパッシベーション膜３０３と電極とを有する太陽電池において、少なくとも前記シリコン基板３０１と接する第１電極３０４層を有し、かつ前記第１電極３０４層の上にパッシベーション膜貫通層３０８を有し、かつ前記パッシベーション膜貫通層３０８上に前記第１電極３０４層と組成が同じかもしくは異なる第２電極３０５層を有するものである。
なお、３０２はエミッタ層であり、３０８はパッシベーション膜貫通層であり、３０６は電界層であり、３０７は裏面電極である。 Examples of the present invention will be described below with reference to FIGS. 3 to 7, but the solar cell of the present invention is not limited to the illustrated examples.
FIG. 3 shows an embodiment of a solar cell according to the present invention.
The solar cell according to the present invention is a solar cell having a passivation film 303 and an electrode on at least one surface of a crystalline silicon substrate 301, and has at least a first electrode 304 layer in contact with the silicon substrate 301, and the first electrode 304 layer. The passivation film penetrating layer 308 is provided on the passivation film penetrating layer 308, and the second electrode 305 layer having the same composition as or different from the first electrode 304 layer is formed on the passivation film penetrating layer 308.
In addition, 302 is an emitter layer, 308 is a passivation film penetration layer, 306 is an electric field layer, and 307 is a back electrode.

本発明の太陽電池の作製方法の一例を以下に述べる。但し、本発明はこの方法で作製された太陽電池に限られるものではない。
高純度シリコンにＢあるいはＧａのようなＩＩＩ族元素をドープし、抵抗率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のような高濃度のアルカリ、もしくは、フッ酸と硝酸の混酸などを用いてエッチングする。単結晶シリコン基板は、ＣＺ法、ＦＺ法いずれの方法によって作製されてもよい。 An example of a method for manufacturing the solar cell of the present invention will be described below. However, the present invention is not limited to the solar cell manufactured by this method.
Slicing damage on the surface of an as-cut single crystal {100} p-type silicon substrate doped with a high purity silicon group III element such as B or Ga and having a resistivity of 0.1 to 5 Ω · cm, concentration of 5 to 60% by mass Etching is performed using a high concentration alkali such as sodium hydroxide or potassium hydroxide, or a mixed acid of hydrofluoric acid and nitric acid. The single crystal silicon substrate may be manufactured by either the CZ method or the FZ method.

引き続き、基板表面にテクスチャと呼ばれる微小な凹凸形成を行う。テクスチャは太陽電池の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、テトラメチルアンモニウムハイドロオキサイドなどのアルカリ溶液（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。上記溶液中に、所定量の２−プロパノールを溶解させ、反応を制御することが多い。   Subsequently, minute unevenness called texture is formed on the substrate surface. Texture is an effective way to reduce solar cell reflectivity. The texture is 10 to 10 in an alkaline solution (concentration 1 to 10% by mass, temperature 60 to 100 ° C.) such as heated sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydrogen carbonate, tetramethylammonium hydroxide. It is easily produced by dipping for about 30 minutes. In many cases, a predetermined amount of 2-propanol is dissolved in the solution to control the reaction.

テクスチャ形成後、塩酸、硫酸、硝酸、フッ酸等、もしくはこれらの混合液の酸性水溶液中で洗浄する。コスト的及び特性的観点から、塩酸中での洗浄が好ましい。清浄度を向上するため、塩酸溶液中に、０．５〜５質量％の過酸化水素水を混合させ、６０〜９０℃に加温して洗浄してもよい。
この基板上に、オキシ塩化リンを用いた気相拡散法によりエミッタ層を形成する。エミッタ層のＰ濃度と深さは、エミッタ層を流れる電流に対する抵抗と、表面パッシベーションの効果の兼ね合いなどで決定されるものである。一般的には、４探針法で測定したエミッタ層のシート抵抗が３０〜１００Ω／□程度になるようにするのがよい。 After texture formation, washing is performed in an acidic aqueous solution of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid or the like, or a mixture thereof. From the viewpoint of cost and characteristics, washing in hydrochloric acid is preferred. In order to improve the cleanliness, 0.5 to 5 mass% hydrogen peroxide solution may be mixed in the hydrochloric acid solution and heated to 60 to 90 ° C. for washing.
On this substrate, an emitter layer is formed by vapor phase diffusion using phosphorus oxychloride. The P concentration and depth of the emitter layer are determined by the balance between the resistance to the current flowing through the emitter layer and the effect of surface passivation. In general, the sheet resistance of the emitter layer measured by the four-probe method is preferably about 30 to 100Ω / □.

シリコンと電極の電気的接触抵抗は、シリコン表面のキャリア濃度、即ちドーパント濃度と電極材料に関係し、一般的な印刷Ａｇ電極においてシリコンと電気的接触を取る場合、シリコン表面のドーパント濃度は少なくとも１×１０19ｃｍ-3以上が必要であり、好ましくは５×１０19ｃｍ-3以上が必要である。 The electrical contact resistance between the silicon and the electrode is related to the carrier concentration of the silicon surface, i.e., the dopant concentration and the electrode material, and when making electrical contact with silicon in a general printed Ag electrode, the dopant concentration on the silicon surface is at least 1 × 10 19 cm −3 or more is required, and preferably 5 × 10 19 cm −3 or more is required.

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、片面の拡散層をアルカリ水溶液などでエッチングしたりして、裏面にｐｎ接合ができないような工夫を施す必要がある。拡散後、表面にできたガラスをフッ酸などで除去する。この後、塩酸／過酸化水素混合溶液や、アンモニア／過酸化水素混合溶液を用いた一般的な半導体シリコン基板の洗浄を加えてもよい。
次いで、上記エミッタ層上に第１電極を形成する。第１電極には、例えばＡｇ粉末等の導電性粒子とガラスフリットを有機バインダーで混合したＡｇペースト等の導電性ペーストを使用し、スクリーン印刷法などにより形成する。 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 diffusion layer on one side is made of an alkaline aqueous solution or the like. It is necessary to devise such that the pn junction cannot be formed on the back surface by etching. After diffusion, the glass formed on the surface is removed with hydrofluoric acid or the like. Thereafter, a general semiconductor silicon substrate may be cleaned using a hydrochloric acid / hydrogen peroxide mixed solution or an ammonia / hydrogen peroxide mixed solution.
Next, a first electrode is formed on the emitter layer. For the first electrode, for example, a conductive paste such as an Ag paste in which conductive particles such as Ag powder and glass frit are mixed with an organic binder is used, and the first electrode is formed by a screen printing method or the like.

前記ガラスフリットは、Ｐｂ系ガラスフリット（例えばＰｂＯ−Ｂ2Ｏ3−ＳｉＯ2系等）、及びＰｂフリー系ガラスフリット（例えばＢｉ2Ｏ3−Ｂ2Ｏ3−ＳｉＯ2−ＣｅＯ2−ＬｉＯ2−ＮａＯ2系等）を用いることができるが、それらに限定されるものではない。ガラスフリットの形状は特に限定されず、例えば球状、不定形等を用いることができる。また、粒子寸法も特に限定されないが、作業性の点等から、粒子寸法の平均値（平均粒子寸法）は０．０１〜１０μｍの範囲が好ましく、０．０５〜１μｍの範囲が更に好ましい。 The glass frit includes a Pb glass frit (for example, PbO—B 2 O 3 —SiO 2 system) and a Pb free glass frit (for example, Bi 2 O 3 —B 2 O 3 —SiO 2 —CeO 2 —LiO 2). it can be used -NaO 2 system, etc.), but is not limited to them. The shape of the glass frit is not particularly limited, and for example, a spherical shape or an indefinite shape can be used. The particle size is not particularly limited, but from the viewpoint of workability, the average particle size (average particle size) is preferably in the range of 0.01 to 10 μm, and more preferably in the range of 0.05 to 1 μm.

前記有機バインダーは、セルロース系樹脂（例えばエチルセルロース、ニトロセルロース等）、（メタ）アクリル系樹脂（例えばポリメチルアクリレート、ポリメチルメタクリレート等）を用いることができるが、それらに限定されるものではない。有機バインダーの添加量は、導電性粒子１００質量部に対し、通常１〜１０質量部であり、好ましくは１〜４質量部である。   As the organic binder, a cellulose resin (for example, ethyl cellulose, nitrocellulose and the like) and a (meth) acrylic resin (for example, polymethyl acrylate and polymethyl methacrylate) can be used, but the organic binder is not limited thereto. The addition amount of the organic binder is usually 1 to 10 parts by mass, preferably 1 to 4 parts by mass with respect to 100 parts by mass of the conductive particles.

次に、受光面の反射防止・パッシベーション膜を形成する。成膜には化学気相堆積装置を用い、ＳｉＮｘ膜などを８０〜１２０ｎｍ、好ましくは約１００ｎｍ程度成膜する。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、Ｈ2ガスによる成膜種の希釈やプロセス圧カの調整、反応ガスの希釈を行い、所望の屈折率を実現する。なお、パッシベーション膜は、ＳｉＮｘに限らず、化学気相堆積法のほか、熱処理や原子層推積などの方法による酸化シリコン、炭化シリコン、酸化アルミニウム、アモルファスシリコン、微結晶シリコン、酸化チタンなどを代わりに用いてもよい。 Next, an antireflection / passivation film for the light receiving surface is formed. A chemical vapor deposition apparatus is used for film formation, and a SiNx film or the like is formed to a thickness of about 80 to 120 nm, preferably about 100 nm. As the reaction gas, monosilane (SiH 4 ) and ammonia (NH 3 ) are often mixed and used, but nitrogen can be used instead of NH 3 , and the film formation species can be diluted with H 2 gas. And adjusting the process pressure and diluting the reaction gas to achieve the desired refractive index. Note that the passivation film is not limited to SiNx, but instead of chemical vapor deposition, silicon oxide, silicon carbide, aluminum oxide, amorphous silicon, microcrystalline silicon, titanium oxide, etc. can be used by methods such as heat treatment and atomic layer deposition. You may use for.

次に、第１電極上に形成されたパッシベーション膜上から、第１電極と重なるように第２電極をスクリーン印刷法などにより形成する。
第２電極には、シリコン基板から第１電極に取り出された電荷が集電電極へ流れる際の配線抵抗損失を抑えるため、高い導電性を持たせるようにしてもよい。このような電極は、第１電極を形成するための電極ペーストと同様のものでもよいが、より高導電性を得るため、例えば第１電極よりＡｇ粒子配合割合を高くしたＡｇペースト等の電極ペーストを使用することで得られる。また、このときの第２電極の抵抗率は低いほどよいが、高くとも５μΩ・ｃｍ以下、好ましくは３μΩ・ｃｍ以下であることが望ましい。 Next, a second electrode is formed by screen printing or the like so as to overlap the first electrode from the passivation film formed on the first electrode.
The second electrode may have high conductivity in order to suppress a wiring resistance loss when the electric charge extracted from the silicon substrate to the first electrode flows to the current collecting electrode. Such an electrode may be the same as the electrode paste for forming the first electrode, but in order to obtain higher conductivity, for example, an electrode paste such as an Ag paste with a higher proportion of Ag particles than the first electrode. Can be obtained by using Further, the resistivity of the second electrode at this time is preferably as low as possible, but it is desirably 5 μΩ · cm or less, preferably 3 μΩ · cm or less at the highest.

この後、第１電極と第２電極を導通させるが、これは電極焼成熱処理により第１電極と第２電極に挟まれたＳｉＮｘ膜が電極ペーストに含まれるガラスフリットと反応し、分解され、Ａｇ粉末等の導電性粒子がＳｉＮｘ膜等のパッシベーション膜を貫通して第１電極と第２電極を電気的に接触させる、いわゆるファイヤースルー法による。ファイヤースルー技術自体は、結晶シリコン太陽電池の製造方法として一般的に広く用いられているものである。   Thereafter, the first electrode and the second electrode are made conductive. This is because the SiNx film sandwiched between the first electrode and the second electrode reacts with the glass frit contained in the electrode paste by the electrode baking heat treatment, decomposes, and Ag. According to a so-called fire-through method, in which conductive particles such as powder penetrate a passivation film such as a SiNx film and electrically contact the first electrode and the second electrode. The fire-through technique itself is generally widely used as a method for manufacturing a crystalline silicon solar cell.

第１電極と第２電極の電極焼成手順は、第１電極を印刷・乾燥し、パッシベーション膜を形成し、第１電極の焼成に続いて、第２電極を印刷・乾燥し、第２電極を焼成するように、第１電極と第２電極の焼成を別々に行ってもよいが、第１電極を印刷・乾燥し、パッシベーション膜を形成し、第２電極を印刷・乾燥し、第１電極と第２電極の焼成を行うという、１回の電極焼成熱処理で両者を同時に焼成してもよい。コストの面からは、後者の１回の電極焼成熱処理で両者を同時に行う方法が望ましい。   The electrode firing procedure of the first electrode and the second electrode includes printing and drying the first electrode, forming a passivation film, printing and drying the second electrode, followed by firing the second electrode and firing the second electrode. The first electrode and the second electrode may be baked separately so as to be fired. However, the first electrode is printed and dried, a passivation film is formed, the second electrode is printed and dried, and the first electrode is fired. And the second electrode may be fired at the same time by a single electrode firing heat treatment. From the viewpoint of cost, the method of performing both of them simultaneously by the latter one electrode baking heat treatment is desirable.

取出電極と集電電極は、例えば図３に示すように取出電極と集電電極を第１電極と第２電極の積層構造としてもよいし、例えば図４に示すように取出電極を第１電極と第２電極の積層構造とし、集電電極を第２電極のみの単層構造としてもよい。
これらの電極構造は、例えば電極ペーストのスクリーン印刷において、第１電極は図５（Ａ）もしくは図５（Ｂ）に示すような取出電極のみのパターン又は図５（Ｄ）に示すような取出電極と集電電極両方のパターニングがされているもので印刷し、第２電極は図５（Ｄ）又は図５（Ｃ）に示すような集電電極のみのパターンで印刷することで作製が可能である。 For example, as shown in FIG. 3, the extraction electrode and the collection electrode may have a laminated structure of the first electrode and the second electrode. For example, as shown in FIG. 4, the extraction electrode may be the first electrode. And the second electrode, and the collecting electrode may have a single layer structure including only the second electrode.
In these electrode structures, for example, in screen printing of electrode paste, the first electrode is a pattern of only the extraction electrode as shown in FIG. 5A or 5B, or the extraction electrode as shown in FIG. The second electrode can be printed with a pattern of only the collector electrode as shown in FIG. 5 (D) or FIG. 5 (C). is there.

また、電極の形成方法は、スクリーン印刷に限らず、インクジェット、ディスペンサー、図版印刷、又はエアゾル堆積などでも可能である。   The method for forming the electrodes is not limited to screen printing, and may be ink jet, dispenser, plate printing, aerosol deposition, or the like.

なお、前記第２電極のみからなる単層電極を部分的に有する構造とする場合、第２電極は図４に示すように、例えばファイヤースルーによりパッシベーション層４０３を貫通してエミッタ層４０２に接していてもよいし、図６のようにパッシベーション層６０３を貫通しなくてもよい。
前記第２電極のみからなる単層電極直下にパッシベーション膜を残した場合、この部分によってシリコン表面のキャリアの再結合が抑制され、太陽電池特性を改善することが可能である。電極ペーストのパッシベーション膜貫通性は、ガラスフリット添加量で調整される。従って、この場合の第２電極の形成には、ガラスフリット添加量が比較的少ない電極ペーストが用いられる。 In the case of a structure in which a single-layer electrode composed of only the second electrode is partially provided, the second electrode is in contact with the emitter layer 402 through the passivation layer 403 by fire-through, for example, as shown in FIG. Alternatively, the passivation layer 603 may not be penetrated as shown in FIG.
When a passivation film is left immediately below the single-layer electrode composed of only the second electrode, recombination of carriers on the silicon surface is suppressed by this portion, and solar cell characteristics can be improved. The passivation film penetrability of the electrode paste is adjusted by the glass frit addition amount. Accordingly, in this case, an electrode paste with a relatively small amount of glass frit added is used to form the second electrode.

裏面電極は、Ａｌ粉末を有機バインダーで混合したペーストをスクリーン印刷して形成する。印刷後、５〜３０分間，６００〜９００℃の温度で焼成して、裏面電極と電界層が形成される。
なお、電界層の形成には例えば臭化ホウ素の気相拡散などにより行うことも可能である。この場合、配線抵抗を抑制する観点から、裏面電極形成にはＡｇペーストを使用するのが好ましい。
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。また各面の電極を形成する順番は入れ替えてもよい。 The back electrode is formed by screen printing a paste in which Al powder is mixed with an organic binder. After printing, the back electrode and the electric field layer are formed by baking at a temperature of 600 to 900 ° C. for 5 to 30 minutes.
The electric field layer can be formed, for example, by vapor phase diffusion of boron bromide. In this case, from the viewpoint of suppressing the wiring resistance, it is preferable to use an Ag paste for forming the back electrode.
The back electrode and the light-receiving surface electrode can be fired at once. The order of forming the electrodes on each surface may be changed.

《裏面に適用する場合》
本発明による第１電極と第２電極の組み合わせで構成される電極は、太陽電池の非受光面に適用することも可能である。
図７は本発明の電極を受光面と非受光面の両方に適用した場合の一例である。
非受光面をこのような構造にすることで、非受光面を電界層７０６とパッシベーション膜７０３で覆うことができ、光生成キャリアの収集効率を上げることができる。なお、パッシベーション効果が十分高いパッシベーション膜が得られる場合には、電界層７０６は形成しなくてもよい。 <When applied to the back side>
The electrode comprised by the combination of the 1st electrode and 2nd electrode by this invention can also be applied to the non-light-receiving surface of a solar cell.
FIG. 7 shows an example in which the electrode of the present invention is applied to both the light receiving surface and the non-light receiving surface.
With such a structure of the non-light-receiving surface, the non-light-receiving surface can be covered with the electric field layer 706 and the passivation film 703, and the collection efficiency of photogenerated carriers can be increased. Note that in the case where a passivation film having a sufficiently high passivation effect is obtained, the electric field layer 706 is not necessarily formed.

非受光面の第１電極７０４ｂと非受光面の第２電極７０５ｂの形状や構成は、図２〜図６の受光面電極と同様にすることができる。即ち、非受光面において取出電極を第１電極と第２電極の積層構造とし、集電電極を第２電極のみの単層構造にしてもよいし、取出電極と集電電極をそれぞれ第１電極及び第２電極の単層構造としてもよいし、取出電極と集電電極の両方を第１電極と第２電極の積層構造にしてもよい。   The shapes and configurations of the first electrode 704b on the non-light-receiving surface and the second electrode 705b on the non-light-receiving surface can be the same as those of the light-receiving surface electrodes in FIGS. That is, on the non-light-receiving surface, the extraction electrode may have a laminated structure of the first electrode and the second electrode, and the collecting electrode may have a single-layer structure having only the second electrode, or the extraction electrode and the collecting electrode may each be the first electrode. In addition, a single-layer structure of the second electrode may be used, or both the extraction electrode and the collecting electrode may be a stacked structure of the first electrode and the second electrode.

非受光面には、基板を透過した光を再度取り込むために反射材を設けることが好ましい（図示せず）。反射材には、真空蒸着などで成膜されるＡｌやＡｇなどを用いてもよいが、付加的な処理を行わず、太陽電池モジュールに白色バックシートなどを用いるだけでも十分に効果は得られる。一方、反射材を用いずに、裏面からも散乱光などを入射させて発電することも可能で、更には上記非受光面を受光面側になるように太陽電池を配置して発電させることも可能である。   A reflection material is preferably provided on the non-light-receiving surface (not shown) in order to capture again the light transmitted through the substrate. As the reflective material, Al or Ag formed by vacuum deposition or the like may be used, but a sufficient effect can be obtained only by using a white back sheet or the like for the solar cell module without performing additional processing. . On the other hand, it is possible to generate power by making scattered light incident from the back side without using a reflective material, and it is also possible to generate power by arranging solar cells so that the non-light receiving surface is on the light receiving surface side. Is possible.

《Ｎ型基板の場合》
以上、Ｐ型シリコン基板を用いた場合を例に挙げて本発明の太陽電池についての実施形態を説明したが、本発明は、Ｎ型シリコン基板を用いた太陽電池に適用することもできる。
この場合には、図７を例に説明すると、シリコン基板７０１、電界層７０６をＮ型とし、エミッタ層７０２をＰ型にする。 << N-type substrate >>
As mentioned above, although the embodiment about the solar cell of this invention was mentioned taking the case where a P-type silicon substrate was used as an example, this invention can also be applied to the solar cell using an N-type silicon substrate.
In this case, referring to FIG. 7 as an example, the silicon substrate 701 and the electric field layer 706 are N-type, and the emitter layer 702 is P-type.

ここでシリコン基板７０１には、一般には高純度シリコンにＰあるいはＳｂのようなＶ族元素をドープし、抵抗率０．１〜５Ω・ｃｍとしたｎ型結晶シリコンを用いる。またエミッタ層７０２は、例えば臭化ホウ素を用いた気相拡散法によりＢをドーピングすることにより形成でき、また電界層７０６はオキシ塩化リンを用いた気相拡散法などにより形成することができる。   Here, as the silicon substrate 701, n-type crystalline silicon having a resistivity of 0.1 to 5 Ω · cm by doping high purity silicon with a group V element such as P or Sb is generally used. Further, the emitter layer 702 can be formed by doping B by a vapor phase diffusion method using, for example, boron bromide, and the electric field layer 706 can be formed by a vapor phase diffusion method using phosphorus oxychloride.

［実施例及び比較例］
本発明の有効性を確認するため、一般的な多層電極構造の太陽電池と本発明の多層電極構造の太陽電池の発電性能比較を行った。
基板厚さ２５０μｍ、１２５ｍｍ角、比抵抗１Ω・ｃｍの、ボロンドープ｛１００｝ｐ型アズカットシリコン基板９０枚に対し、熱濃水酸化カリウム水溶液によりダメージ層を除去後、水酸化カリウム／２−プ口パノール水溶液中に浸漬して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中で洗浄を行った。
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、受光面にリンを高濃度ドーピングしてシート抵抗５０Ω／□のｐｎ接合を形成した。この後、非受光面の拡散層をフッ硝酸でエッチング除去し、フッ酸にてリンガラスを除去し、アンモニア／過酸化水素混合溶液で洗浄後、リンス洗浄し、乾燥させた。 [Examples and Comparative Examples]
In order to confirm the effectiveness of the present invention, the power generation performance of a solar cell having a general multilayer electrode structure and a solar cell having a multilayer electrode structure of the present invention was compared.
After removing the damaged layer with hot concentrated potassium hydroxide aqueous solution on 90 boron-doped {100} p-type as-cut silicon substrates having a substrate thickness of 250 μm, 125 mm square and specific resistance of 1 Ω · cm, potassium hydroxide / 2-p Texture formation was performed by dipping in an aqueous solution of oral propanol, followed by washing in a hydrochloric acid / hydrogen peroxide mixed solution.
Next, heat treatment was performed in a phosphorus oxychloride atmosphere at 870 ° C. with the back surfaces overlapped, and the light receiving surface was doped with phosphorus at a high concentration to form a pn junction having a sheet resistance of 50Ω / □. Thereafter, the diffusion layer on the non-light-receiving surface was etched away with hydrofluoric acid, the phosphor glass was removed with hydrofluoric acid, washed with an ammonia / hydrogen peroxide mixed solution, rinsed and dried.

ここで上記基板を、条件１、条件２、条件３の３組各３０枚に分け、以下の通りそれぞれ加工した。
なお、以下各条件毎に受光面電極として異なるＡｇペーストを用いたが、いずれも図５（Ｄ）にあるような取出電極と集電電極が同一スクリーンにパターニングされた製版を用いて印刷した。また、電極ペーストの印刷条件については予め条件出しを行い、各条件とも焼成後に同等の線幅と断面積が得られるように印圧やスキージ角度などの印刷条件を制御した。 Here, the substrate was divided into 30 groups each of three sets of condition 1, condition 2, and condition 3, and processed as follows.
In the following, different Ag pastes were used as the light-receiving surface electrode for each condition, but printing was performed using a plate making in which the extraction electrode and the collecting electrode as shown in FIG. 5D were patterned on the same screen. In addition, the printing conditions of the electrode paste were determined in advance, and printing conditions such as printing pressure and squeegee angle were controlled so that the same line width and cross-sectional area were obtained after firing for each condition.

条件１は、従来技術による比較例の一つであり、上記洗浄後の基板に、パッシベーション膜として、プラズマＣＶＤ装置を用いて膜厚９０ｎｍのＳｉＮｘ膜を受光面の試料全面に形成した。
次いで第１電極として一般的なファイヤースルー型ペーストのペーストＡ（ガラスフリット含有量が比較的多い）をスクリーン印刷及び乾燥した。
次いで第２電極として高導電性ＡｇペーストのペーストＢ（ガラスフリット含有量が比較的少ない）を第１電極と完全に重なるようにスクリーン印刷した。
この後、最適化された条件である７８０℃の焼成を大気雰囲気で行った。 Condition 1 is one of comparative examples according to the prior art, and a 90 nm-thickness SiNx film was formed on the entire surface of the light-receiving surface as a passivation film on the substrate after the cleaning using a plasma CVD apparatus.
Next, a paste A (a relatively high glass frit content) of a general fire-through paste as a first electrode was screen-printed and dried.
Next, a high-conductivity Ag paste B (having a relatively small glass frit content) was screen-printed as a second electrode so as to completely overlap the first electrode.
Thereafter, baking at 780 ° C., which is an optimized condition, was performed in an air atmosphere.

条件２は、従来技術による他の比較例であり、上記洗浄後の基板に、パッシベーション膜として、プラズマＣＶＤ装置を用いて膜厚９０ｎｍのＳｉＮｘ膜を受光面の試料全面に形成した。
次いで第１電極として上記ペーストＡよりガラスフリット含有量が少ないファイヤースルー型ペーストのペーストＣをスクリーン印刷及び乾燥した。
次いで第２電極として高導電性ＡｇペーストのペーストＢ（ガラスフリット含有量が比較的少ない）を第１電極と完全に重なるようにスクリーン印刷した。
この後、最適化された条件である７８０℃の焼成を大気雰囲気で行った。 Condition 2 is another comparative example according to the prior art. A SiNx film having a thickness of 90 nm was formed as a passivation film on the entire surface of the sample on the light receiving surface as a passivation film using the plasma CVD apparatus.
Subsequently, a fire-through paste C having a glass frit content lower than that of the paste A was screen printed and dried as a first electrode.
Next, a high-conductivity Ag paste B (having a relatively small glass frit content) was screen-printed as a second electrode so as to completely overlap the first electrode.
Thereafter, baking at 780 ° C., which is an optimized condition, was performed in an air atmosphere.

条件３は、本発明の適用例であり、上記洗浄後の基板に、第１電極として上記ペーストＡよりガラスフリット含有量が少ないファイヤースルー型ペーストのペーストＣをスクリーン印刷及び乾燥した。次いでパッシベーション膜として、プラズマＣＶＤ装置を用いて膜厚９０ｎｍのＳｉＮｘ膜を受光面の試料全面に形成した。
次いで第２電極として高導電性ＡｇペーストのペーストＢ（ガラスフリット含有量が比較的少ない）を第１電極と完全に重なるようにスクリーン印刷した。
この後、最適化された条件である７８０℃の焼成を大気雰囲気で行った。 Condition 3 is an application example of the present invention, and a fire-through paste C having a glass frit content less than that of the paste A as a first electrode was screen-printed and dried on the cleaned substrate. Next, as a passivation film, a 90 nm-thickness SiNx film was formed on the entire surface of the light-receiving surface using a plasma CVD apparatus.
Next, a high-conductivity Ag paste B (having a relatively small glass frit content) was screen-printed as a second electrode so as to completely overlap the first electrode.
Thereafter, baking at 780 ° C., which is an optimized condition, was performed in an air atmosphere.

次に上記全ての太陽電池の裏面にＡｌペーストを試料全面に塗付し、この後、最適化された条件である７７０℃の焼成を大気雰囲気で行った。上記の条件１、条件２、条件３の太陽電池について、受光面電極の形状を確認するため、各条件から５試料を抽出し、試料面内９箇所の取出電極線幅と断面積をレーザー顕微鏡により測定した。   Next, an Al paste was applied to the entire surface of the sample on the back surface of all the solar cells, and thereafter, baking at 770 ° C., which is an optimized condition, was performed in an air atmosphere. In order to confirm the shape of the light-receiving surface electrode for the solar cells under the above conditions 1, 2 and 3, 5 samples were extracted from each condition, and the extraction electrode line widths and cross-sectional areas at 9 locations in the sample surface were measured with a laser microscope. It was measured by.

電極焼成熱処理前の各条件におけるエミッタ層上の構造と、第１電極及び第２電極の電極ペースト種類と、電極線幅及び断面積の測定値の平均値を下記表１に示す。その結果、全条件で同等の電極形状が得られていることが確認できた。   The structure of the emitter layer under each condition before the electrode firing heat treatment, the electrode paste types of the first electrode and the second electrode, and the average values of the measured values of the electrode line width and cross-sectional area are shown in Table 1 below. As a result, it was confirmed that an equivalent electrode shape was obtained under all conditions.

次に、全ての太陽電池を、エアマス１．５の擬似太陽光を用いた電流電圧測定器で特性測定を行った。
各条件における太陽電池特性の平均値を下記表２に示す。 Next, the characteristics of all the solar cells were measured with a current-voltage measuring device using artificial sunlight having an air mass of 1.5.
The average value of the solar cell characteristics under each condition is shown in Table 2 below.

条件１と条件２の比較より、従来の多層電極構造において、第１電極の電極ペーストからガラスフリット含有量を減らすと、曲線因子が高くなった。
条件２と条件３の比較より、条件３の本発明の多層電極構造において、条件２と同じ電極ペーストを用いたにも拘わらず曲線因子が最も高く、高い太陽電池特性が得られた。 From the comparison between Condition 1 and Condition 2, in the conventional multilayer electrode structure, when the glass frit content was reduced from the electrode paste of the first electrode, the fill factor increased.
From the comparison of Condition 2 and Condition 3, in the multilayer electrode structure of the present invention of Condition 3, the highest curve factor was obtained and high solar cell characteristics were obtained despite using the same electrode paste as in Condition 2.

次に、各条件からそれぞれ１５枚を抽出し、シリコン基板と電極の接触抵抗と配線抵抗を測定した。接触抵抗定量はラダー法で行い、配線抵抗定量は取出電極部分を太陽電池から部分的に切り出した試料において、電極両端に探針を置いたときの電流電圧値から求めた。
図８は各条件に対する各抵抗の相対値を示したもので、条件１の平均値を１とした。 Next, 15 pieces were extracted from each condition, and the contact resistance and wiring resistance between the silicon substrate and the electrode were measured. Contact resistance quantification was performed by a ladder method, and wiring resistance quantification was obtained from a current voltage value when a probe was placed at both ends of an electrode in a sample obtained by partially cutting out an extraction electrode portion from a solar cell.
FIG. 8 shows the relative value of each resistance with respect to each condition.

条件２の結果より、従来の多層電極構造において、第１電極の電極ペーストからガラスフリット含有量を減らすと、接触抵抗は上昇し、配線抵抗は低下した。表２において条件２が低い曲線因子となったのは、接触抵抗の上昇による結果であると言える。   From the result of Condition 2, in the conventional multilayer electrode structure, when the glass frit content was reduced from the electrode paste of the first electrode, the contact resistance increased and the wiring resistance decreased. In Table 2, it can be said that Condition 2 has a low fill factor due to an increase in contact resistance.

条件３の結果より、本発明の多層電極構造においては、条件２と同じ電極ペーストを用いたにも拘わらず、条件１より接触抵抗、配線抵抗のいずれもが低くなっていることが判る。従って、表２において条件３が最も高い曲線因子となったのは、接触抵抗と配線抵抗が抑制された結果であると言える。   From the results of Condition 3, it can be seen that in the multilayer electrode structure of the present invention, both the contact resistance and the wiring resistance are lower than those in Condition 1 even though the same electrode paste as in Condition 2 is used. Therefore, in Table 2, it can be said that Condition 3 has the highest fill factor as a result of suppression of contact resistance and wiring resistance.

１０１、２０１、３０１、４０１、６０１、７０１・・・シリコン基板
１０２、２０２、３０２、４０２、６０２、７０２・・・エミッタ層
１０３、２０３、３０３、４０３、６０３、７０３・・・パッシベーション膜
１０４・・・取出電極
２０４、３０４、４０４、６０４、７０４ａ、７０４ｂ・・・第１電極
１０５・・・集電電極
２０５、３０５、４０５、６０５、７０５ａ、７０５ｂ・・・第２電極
１０６、２０６、３０６、４０６、６０６、７０６・・・電界層
１０７、２０７、３０７、４０７、６０７・・・裏面電極
１０８、２０８、３０８、４０８、６０８、７０８・・・パッシベーション膜貫通層
５０１・・・取出電極印刷パターン
５０２・・・集電電極印刷パターン 101, 201, 301, 401, 601, 701 ... Silicon substrates 102, 202, 302, 402, 602, 702 ... Emitter layers 103, 203, 303, 403, 603, 703 ... Passivation film 104 .. Extraction electrodes 204, 304, 404, 604, 704a, 704b ... first electrode 105 ... collecting electrodes 205, 305, 405, 605, 705a, 705b ... second electrodes 106, 206, 306 , 406, 606, 706 ... electric field layers 107, 207, 307, 407, 607 ... backside electrodes 108, 208, 308, 408, 608, 708 ... passivated through layer 501 ... extraction electrode printing Pattern 502 ... Collecting electrode printing pattern

Claims (9)

結晶シリコン基板の少なくとも第一主表面のエミッタ層上に導電性粒子とガラスフリットを含有する第１電極形成用電極ペーストを塗布し、その上にパッシベーション膜を形成し、更にパッシベーション膜上に第１電極と部分的に重なり合うように導電性粒子とガラスフリットを含有する第２電極形成用電極ペーストを塗布し、次いで電極焼成熱処理により第１及び第２電極を形成すると共に、前記第１電極及び第２電極の重なり合った部分の電極ペーストがこれら間のパッシベーション膜をそれぞれファイヤースルーすることにより前記第１及び第２電極間を導通するパッシベーション膜貫通層を形成すると共に、前記第２電極の第１電極とは重なり合わない部分の電極ペーストでその直下のパッシベーション膜を貫通させずに該パッシベーション膜を残すことを特徴とする太陽電池の製造方法。   A first electrode forming electrode paste containing conductive particles and glass frit is applied on at least the first main surface emitter layer of the crystalline silicon substrate, a passivation film is formed thereon, and further a first film is formed on the passivation film. A second electrode forming electrode paste containing conductive particles and glass frit is applied so as to partially overlap the electrode, and then the first and second electrodes are formed by electrode firing heat treatment. The electrode paste of the overlapping part of the two electrodes fires through the passivation film between them to form a passivation film through layer that conducts between the first and second electrodes, and the first electrode of the second electrode The electrode paste is not overlapped with the electrode paste without penetrating the passivation film directly below it. Method of manufacturing a solar cell characterized by leaving a passivation film. 結晶シリコン基板の少なくとも第一主表面のエミッタ層上に導電性粒子とガラスフリットを含有する第１電極形成用電極ペーストを塗布し、その上にパッシベーション膜を形成した後、電極焼成熱処理により第１電極を形成すると共に、前記電極ペーストをこの第１電極形成位置に対応するパッシベーション膜にファイヤースルーさせ、次に前記パッシベーション膜上に第１電極と部分的に重なり合うように導電性粒子とガラスフリットを含有する第２電極形成用電極ペーストを塗布し、次いで電極焼成熱処理により第２電極を形成すると共に、第２電極形成用電極ペーストがこの第２電極形成位置に対応するパッシベーション膜をファイヤースルーすることにより前記第１電極と重なり合った部分において前記第１及び第２電極間を導通するパッシベーション膜貫通層を形成すると共に、前記第１電極とは重なり合わない部分においてその直下のパッシベーション膜を貫通させずに該パッシベーション膜を残すことを特徴とする太陽電池の製造方法。   A first electrode forming electrode paste containing conductive particles and glass frit is applied on at least the first main surface emitter layer of the crystalline silicon substrate, a passivation film is formed on the first electrode forming electrode paste, and then a first electrode heat treatment is performed. In addition to forming an electrode, the electrode paste is fired through the passivation film corresponding to the first electrode formation position, and then conductive particles and glass frit are partially overlapped with the first electrode on the passivation film. The second electrode forming electrode paste is applied, then the second electrode is formed by electrode firing heat treatment, and the second electrode forming electrode paste fires through the passivation film corresponding to the second electrode forming position. To conduct between the first and second electrodes in a portion overlapping the first electrode. And forming a passivation film through layer, method of manufacturing a solar cell characterized by leaving the passivation film, a passivation film without penetrating below it in the portion not overlapping the first electrode. 前記第１電極として取出電極のみのパターンで塗布し、前記第２電極として取出電極及び集電電極のパターンであって該取出電極のパターンが第１電極と重なり合うように塗布することを特徴とする請求項１又は２記載の太陽電池の製造方法。   The first electrode is applied in a pattern of only an extraction electrode, and the second electrode is a pattern of an extraction electrode and a collecting electrode, and the extraction electrode pattern is applied so as to overlap the first electrode. The manufacturing method of the solar cell of Claim 1 or 2. 前記第１電極として略平行な複数本からなる点線状パターンを塗布し、前記第２電極の取出電極として略平行な複数本からなる直線状パターンを塗布し、前記第２電極の取出電極において第１電極と重なり合わず単層となる直下の前記パッシベーション膜を残すことを特徴とする請求項３記載の太陽電池の製造方法。   A plurality of substantially parallel dotted lines are applied as the first electrodes, and a plurality of substantially parallel linear patterns are applied as the second electrode extraction electrodes. 4. The method for manufacturing a solar cell according to claim 3, wherein the passivation film immediately below which is a single layer without overlapping with one electrode is left. 請求項１〜４のいずれか１項記載の太陽電池の製造方法により製造された太陽電池であって、結晶シリコン基板の少なくとも第一主表面のエミッタ層上に直接形成された第１電極層と、この第１電極層を覆って前記エミッタ層上に形成されたパッシベーション膜と、このパッシベーション膜を介して前記第１電極層に部分的に重なり合って形成された第２電極層とを有し、前記第１及び第２電極層間の重なり合った部分のパッシベーション膜が第１及び第２電極層のファイヤースルーによってこれら第１及び第２電極層間を導通するパッシベーション膜貫通層として形成されてなり、前記第２電極の第１電極とは重なり合わず単層となった部分の直下に前記パッシベーション膜を有することを特徴とする太陽電池。   A solar cell manufactured by the method for manufacturing a solar cell according to any one of claims 1 to 4, wherein the first electrode layer is formed directly on the emitter layer on at least the first main surface of the crystalline silicon substrate; A passivation film formed on the emitter layer so as to cover the first electrode layer, and a second electrode layer formed so as to partially overlap the first electrode layer through the passivation film, The overlapping portion of the passivation film between the first and second electrode layers is formed as a passivation film through layer that conducts between the first and second electrode layers by fire-through of the first and second electrode layers. A solar cell comprising the passivation film immediately below a portion that is a single layer without overlapping with the first electrode of two electrodes. 前記第１電極が取出電極のみからなり、前記第２電極が取出電極及び集電電極からなっており、第１電極及び第２電極の取出電極が重なり合っていることを特徴とする請求項５記載の太陽電池。   The said 1st electrode consists only of an extraction electrode, the said 2nd electrode consists of an extraction electrode and a current collection electrode, and the extraction electrode of the 1st electrode and the 2nd electrode has overlapped. Solar cells. 前記シリコン基板の第一主表面上において、前記第１電極が略平行な複数本からなる点線状パターンからなり、前記第２電極の取出電極が略平行な複数本からなる直線状パターンからなり、前記第２電極の取出電極において第１電極とは重なり合わず単層となる直下に前記パッシベーション膜を有することを特徴とする請求項６記載の太陽電池。   On the first main surface of the silicon substrate, the first electrode is composed of a plurality of substantially parallel dotted lines, and the second electrode extraction electrode is composed of a plurality of substantially parallel linear patterns, The solar cell according to claim 6, wherein the passivation film has the passivation film directly below the first electrode without overlapping with the first electrode. 前記第１電極と前記第２電極の組み合わせでなる電極が、太陽電池の受光面側に形成されていることを特徴とする請求項５〜７のいずれか１項記載の太陽電池。   The solar cell according to claim 5, wherein an electrode formed by a combination of the first electrode and the second electrode is formed on a light receiving surface side of the solar cell. 前記パッシベーション膜は、酸化シリコン、窒化シリコン、炭化シリコン、酸化アルミニウム、アモルファスシリコン、微結晶シリコン、酸化チタンのいずれか又はその組み合わせからなる請求項５〜８のいずれか１項記載の太陽電池。   The solar cell according to claim 5, wherein the passivation film is made of any one of silicon oxide, silicon nitride, silicon carbide, aluminum oxide, amorphous silicon, microcrystalline silicon, and titanium oxide, or a combination thereof.
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