WO2012140808A1 - Solar cell and manufacturing method for same, and solar cell module - Google Patents
Solar cell and manufacturing method for same, and solar cell module Download PDFInfo
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- WO2012140808A1 WO2012140808A1 PCT/JP2011/078553 JP2011078553W WO2012140808A1 WO 2012140808 A1 WO2012140808 A1 WO 2012140808A1 JP 2011078553 W JP2011078553 W JP 2011078553W WO 2012140808 A1 WO2012140808 A1 WO 2012140808A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
- H01L31/035272—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions characterised by at least one potential jump barrier or surface barrier
- H01L31/035281—Shape of the body
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
- H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/547—Monocrystalline silicon PV cells
Definitions
- Such a conventional solar cell is manufactured as follows. For example, using a wet etching process using a mixed solution of an alkali solution and alcohol, a mixed acid solution of hydrofluoric acid and nitric acid, or a dry etching process such as a reactive ion etching (RIE) method, a p-type simple substance is used. Micro unevenness is formed on the surface of a crystalline silicon substrate (hereinafter referred to as a substrate). The fine irregularities on the surface are formed in order to suppress light reflection from the outside, confine the light in the substrate, and increase the light-electron conversion efficiency for converting the light into electricity.
- RIE reactive ion etching
- a low resistance diffusion layer is formed by diffusing a dopant in a high concentration over the entire light receiving surface.
- the lower resistance diffusion layer other than the electrode formation region is removed by masking and etching the lower portion of the electrode that will eventually become the low resistance diffusion layer.
- the dopant is diffused at a low concentration over the entire light receiving surface to form a high resistance diffusion layer.
- FIG. 4 is a plan view of a principal part on the light-receiving surface side of the solar battery cell, showing an example of the shape of the low resistance diffusion layer according to the fourth embodiment of the present invention.
- FIG. 5 is a plan view of a main part on the light receiving surface side of the solar battery cell showing an example of the positional relationship between the low resistance diffusion layer and the light receiving surface side electrode.
- FIG. 6 is a plan view of a principal part on the light receiving surface side of the solar battery cell showing an example of the positional relationship between the low resistance diffusion layer and the light receiving surface side electrode according to the fifth embodiment of the present invention.
- FIG. 7 is a plan view of a principal part on the light receiving surface side of the solar battery cell showing an example of the positional relationship between the low resistance diffusion layer and the light receiving surface side electrode according to the fifth embodiment of the present invention.
- the solar battery cell according to Embodiment 1 shown in FIGS. 1-1 and 1-2 is obtained.
- the contact resistance between the light receiving surface side electrode 10 and the silicon substrate 1 is reduced and the adhesion strength is improved, and the photoelectric conversion efficiency and long-term reliability are improved. High solar cells can be realized.
Abstract
This solar cell comprises the following: a first conductivity type semiconductor substrate (1) in which a second conductivity type impurity diffusion layer having two different types of electrical resistance values is provided on a light receiving surface side; a light receiving surface side electrode (10) provided on the light receiving surface side of the semiconductor substrate (1); and rear surface side electrodes (8, 9) provided on the rear surface side of the semiconductor substrate (1). The second conductivity type impurity diffused layer comprises a high resistance diffusion layer (6) of which the surface is uneven, and a low resistance diffusion layer (2) having a smaller electrical resistance value than the first impurity diffusion layer (6). By providing the light receiving surface side electrode (10) astride and in contact with both a region of the low resistance diffusion layer (2) and a partial region of the high resistance diffusion layer (6) which is adjacent to the low resistance diffusion layer (2), and in electrical contact with the high resistance diffusion layer (6) and the low resistance diffusion layer (2), contact resistance can be lowered and adhesion strength can be improved between the light receiving surface side electrode (10) and the semiconductor substrate (1).
Description
本発明は、太陽電池およびその製造方法、太陽電池モジュールに関するものである。
The present invention relates to a solar cell, a manufacturing method thereof, and a solar cell module.
従来の太陽電池は、多結晶シリコンもしくは単結晶シリコンのｐ型シリコン基板の受光面全体にｎ型の不純物拡散層が形成され、受光面側の表面に微小な凹凸が設けられている。微小凹凸上には反射防止膜が形成され、その上に櫛形状に表電極が設けられている。また、ｐ型シリコン基板の裏面側には、裏面全体に電極が設けられている。
In conventional solar cells, an n-type impurity diffusion layer is formed on the entire light-receiving surface of a polycrystalline silicon or single-crystal silicon p-type silicon substrate, and minute irregularities are provided on the surface on the light-receiving surface side. An antireflection film is formed on the minute irregularities, and a surface electrode is provided in a comb shape thereon. Further, on the back side of the p-type silicon substrate, electrodes are provided on the entire back side.
このような従来の太陽電池は以下のようにして作製されている。たとえばアルカリ溶液とアルコールとの混合液やフッ酸と硝酸との混酸溶液を用いたウェットエッチングプロセスや、リアクティブイオンエッチング（Reactive Ion Etching：ＲＩＥ）法などのドライエッチングプロセスを用いて、ｐ型単結晶シリコン基板（以下、基板と呼ぶ）の表面に微小凹凸を形成する。この表面の微細凹凸は、外からの光の反射を抑えて光を基板内に閉じ込め、光を電気に変換する光－電子変換効率を上げるために形成される。
Such a conventional solar cell is manufactured as follows. For example, using a wet etching process using a mixed solution of an alkali solution and alcohol, a mixed acid solution of hydrofluoric acid and nitric acid, or a dry etching process such as a reactive ion etching (RIE) method, a p-type simple substance is used. Micro unevenness is formed on the surface of a crystalline silicon substrate (hereinafter referred to as a substrate). The fine irregularities on the surface are formed in order to suppress light reflection from the outside, confine the light in the substrate, and increase the light-electron conversion efficiency for converting the light into electricity.
つぎに、オキシ塩化リン（ＰＯＣｌ３）ガス中で気相拡散法により基板の表層にｎ型不純物拡散層を形成する。基板の表面に形成された酸化膜をフッ化水素に浸して除去した後に、基板の受光面側の表面に反射防止膜である窒化シリコンをプラズマＣＶＤ（化学的気層成長）法により形成する。つぎに、基板の受光面側の表面に、銀ペーストを用いて印刷法により櫛形状にパターン化した表電極形成を行う。基板の裏面側には、アルミニウムペーストを用いて裏面のほぼ全体にアルミニウム電極を形成し、一部には外部取り出し電極として銀電極を印刷法により形成する。そして、電極ペーストを２００℃の温度で乾燥した後に、７００℃～８００℃の温度で電極ペーストを焼成し、太陽電池素子が完成する。
Next, an n-type impurity diffusion layer is formed on the surface layer of the substrate by a vapor phase diffusion method in phosphorus oxychloride (POCl 3) gas. After the oxide film formed on the surface of the substrate is removed by immersion in hydrogen fluoride, silicon nitride as an antireflection film is formed on the surface on the light receiving surface side of the substrate by a plasma CVD (chemical vapor deposition) method. Next, a surface electrode is formed on the surface of the substrate on the light-receiving surface side, which is patterned into a comb shape by a printing method using a silver paste. On the back surface side of the substrate, an aluminum electrode is formed on almost the entire back surface using an aluminum paste, and a silver electrode is formed on a part of the substrate as an external extraction electrode by a printing method. Then, after drying the electrode paste at a temperature of 200 ° C., the electrode paste is baked at a temperature of 700 ° C. to 800 ° C. to complete a solar cell element. *
一方、太陽電池の光－電子変換効率を向上するために、受光面側電極の領域よりも広い領域に高濃度のドーパント層（低抵抗拡散層）を形成してシート抵抗を低くすることで導電性を上げ、受光面側におけるそれ以外の領域に低濃度のドーパント層（高抵抗拡散層）を形成して電子の再結合を抑制するセレクティブエミッタ構造がある（たとえば、特許文献１参照）。
On the other hand, in order to improve the photoelectric conversion efficiency of the solar cell, a high concentration dopant layer (low resistance diffusion layer) is formed in a region wider than the region of the light receiving surface side electrode to reduce the sheet resistance. There is a selective emitter structure that suppresses electron recombination by forming a low-concentration dopant layer (high resistance diffusion layer) in other regions on the light receiving surface side (see, for example, Patent Document 1).
しかしながら、上記従来の技術によれば、まず受光面全体にドーパントを高濃度に拡散して低抵抗拡散層を形成する。つぎに、最終的に低抵抗拡散層にする電極下部の部分をマスキングし、エッチングすることにより電極形成領域以外の低抵抗拡散層を除去する。そして、受光面全体にドーパントを低濃度に拡散して高抵抗拡散層を形成する。
However, according to the conventional technique, first, a low resistance diffusion layer is formed by diffusing a dopant in a high concentration over the entire light receiving surface. Next, the lower resistance diffusion layer other than the electrode formation region is removed by masking and etching the lower portion of the electrode that will eventually become the low resistance diffusion layer. Then, the dopant is diffused at a low concentration over the entire light receiving surface to form a high resistance diffusion layer.
このような工程では、電極形成領域はマスキングされているためエッチングされず、表面形状はほぼ平坦な形状になる。このため、この電極形成領域（低抵抗拡散層）とこの上に形成する受光面側電極との密着面積が減少し、接触抵抗の増大による太陽電池の特性の劣化、および電極密着強度の低下に起因した電極剥離により長期信頼性を劣化させる原因となる、という問題があった。
In such a process, since the electrode forming region is masked, it is not etched, and the surface shape is almost flat. For this reason, the contact area between the electrode formation region (low resistance diffusion layer) and the light-receiving surface side electrode formed thereon is reduced, resulting in deterioration of solar cell characteristics due to increase in contact resistance and reduction in electrode contact strength. There was a problem that the long-term reliability deteriorated due to the electrode peeling.
また、この場合の電極形成領域（低抵抗拡散層）は、受光面側電極の形成時における位置合わせのマージンを考慮して、最終的な電極幅よりも広い領域に設けられる。そして、低抵抗拡散層のうち電極が形成されていない領域は受光面として機能するが、低抵抗拡散層は少数キャリア寿命が短く光－電子変換効率が低いため、この領域で電流の損失が発生する、という問題があった。
In this case, the electrode formation region (low resistance diffusion layer) is provided in a region wider than the final electrode width in consideration of the alignment margin when forming the light receiving surface side electrode. The region where no electrode is formed in the low resistance diffusion layer functions as a light receiving surface. However, since the low resistance diffusion layer has a short minority carrier lifetime and low photoelectric conversion efficiency, current loss occurs in this region. There was a problem of doing.
本発明は、上記に鑑みてなされたものであって、光－電子変換効率および長期信頼性に優れた太陽電池およびその製造方法、太陽電池モジュールを提供することを目的とする。
The present invention has been made in view of the above, and an object thereof is to provide a solar cell excellent in photo-electron conversion efficiency and long-term reliability, a manufacturing method thereof, and a solar cell module.
上述した課題を解決し、目的を達成するために、本発明にかかる太陽電池は、２種類の異なる電気抵抗値を有する第２導電型の不純物拡散層が受光面側に設けられた第１導電型の半導体基板と、前記半導体基板の受光面側に設けられた受光面側電極と、前記半導体基板の裏面側に設けられた裏面側電極とを備え、前記第２導電型の不純物拡散層が、表面が凹凸形状とされた第１不純物拡散層と、前記第１不純物拡散層よりも小さい電気抵抗値を有する第２不純物拡散層とを備える太陽電池において、前記受光面側電極が、前記第２不純物拡散層の領域および前記第２不純物拡散層に隣接する前記第１不純物拡散層の一部領域の２領域にまたがって接触して前記第１不純物拡散層および前記第２不純物拡散層に電気的に接続して設けられること、を特徴とする。
In order to solve the above-described problems and achieve the object, the solar cell according to the present invention is a first conductive material in which a second conductive type impurity diffusion layer having two different electric resistance values is provided on the light receiving surface side. A semiconductor substrate of the type, a light receiving surface side electrode provided on the light receiving surface side of the semiconductor substrate, and a back surface side electrode provided on the back surface side of the semiconductor substrate, wherein the impurity diffusion layer of the second conductivity type is A solar cell comprising: a first impurity diffusion layer having a concavo-convex surface; and a second impurity diffusion layer having an electric resistance value smaller than that of the first impurity diffusion layer. Two regions of the impurity diffusion layer and two regions of the first impurity diffusion layer adjacent to the second impurity diffusion layer are in contact with each other and are electrically connected to the first impurity diffusion layer and the second impurity diffusion layer. To be connected , Characterized by.
本発明によれば、受光面側電極と半導体基板との接触抵抗の低下および密着強度の向上が図られた、光－電子変換効率および長期信頼性の高い太陽電池が得られる、という効果を奏する。
According to the present invention, it is possible to obtain a solar cell with high photo-electron conversion efficiency and long-term reliability in which the contact resistance between the light receiving surface side electrode and the semiconductor substrate is reduced and the adhesion strength is improved. .
以下に、本発明にかかる太陽電池およびその製造方法、太陽電池モジュールの実施の形態を図面に基づいて詳細に説明する。なお、本発明は以下の記述に限定されるものではなく、本発明の要旨を逸脱しない範囲において適宜変更可能である。また、以下に示す図面においては、理解の容易のため、各部材の縮尺が実際とは異なる場合がある。各図面間においても同様である。また、平面図であっても、図面を見易くするためにハッチングを付す場合がある。
Hereinafter, embodiments of a solar cell, a manufacturing method thereof, and a solar cell module according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings. Further, even a plan view may be hatched to make the drawing easy to see.
実施の形態１．
図１－１は、本発明の実施の形態１にかかる太陽電池セルの概略構成を示す要部断面図である。図１－２は、本発明の実施の形態１にかかる太陽電池セルの概略構成を示す要部平面図であり、図１－１は図１－２の線分Ａ－Ａにおける要部断面図である。なお、図１－２においては、反射防止膜および受光面側電極を透過して見ている。Embodiment 1 FIG.
FIG. 1-1 is a cross-sectional view of a principal part showing a schematic configuration of the solar battery cell according to the first embodiment of the present invention. 1-2 is a main part plan view showing a schematic configuration of the solar cell according to the first embodiment of the present invention, and FIG. 1-1 is a main part sectional view taken along line AA in FIG. 1-2. It is. In FIG. 1-2, the light is seen through the antireflection film and the light receiving surface side electrode.
図１－１は、本発明の実施の形態１にかかる太陽電池セルの概略構成を示す要部断面図である。図１－２は、本発明の実施の形態１にかかる太陽電池セルの概略構成を示す要部平面図であり、図１－１は図１－２の線分Ａ－Ａにおける要部断面図である。なお、図１－２においては、反射防止膜および受光面側電極を透過して見ている。
FIG. 1-1 is a cross-sectional view of a principal part showing a schematic configuration of the solar battery cell according to the first embodiment of the present invention. 1-2 is a main part plan view showing a schematic configuration of the solar cell according to the first embodiment of the present invention, and FIG. 1-1 is a main part sectional view taken along line AA in FIG. 1-2. It is. In FIG. 1-2, the light is seen through the antireflection film and the light receiving surface side electrode.
実施の形態１にかかる太陽電池セルは、半導体基板１としてｐ型の単結晶または多結晶のシリコン基板（以下、シリコン基板１と呼ぶ）を用いている。なお、半導体基板１はこれに限定されるものではなく、ｎ型のシリコン基板を用いてもよい。
The solar cell according to the first embodiment uses a p-type single crystal or polycrystalline silicon substrate (hereinafter referred to as silicon substrate 1) as the semiconductor substrate 1. The semiconductor substrate 1 is not limited to this, and an n-type silicon substrate may be used.
シリコン基板１の受光面側には、光を閉じ込めるためのテクスチャー構造を構成する微小凹凸５が１０μｍ程度の深さで形成されている。シリコン基板１の受光面側の表層部にはｎ型不純物拡散層が形成されてｐｎ接合部を形成している。ｎ型不純物拡散層としては、２種類の層が形成されている。すなわち、微小凹凸５の表層部には、ｎ型の不純物が低濃度に拡散された高抵抗拡散層（低濃度不純物拡散層）６が形成されている。また、シリコン基板１の受光面側において微小凹凸５が形成されず突出した領域の表層部には、ｎ型の不純物が高濃度に拡散された低抵抗拡散層（高濃度不純物拡散層）２が形成されている。したがって、高抵抗拡散層６の電気抵抗値を第１電気抵抗値とし、低抵抗拡散層２の電気抵抗値を第２電気抵抗値とすると、第２電気抵抗値は、第１電気抵抗値よりも小さくなる。
On the light receiving surface side of the silicon substrate 1, minute irregularities 5 constituting a texture structure for confining light are formed with a depth of about 10 μm. An n-type impurity diffusion layer is formed in the surface layer portion on the light receiving surface side of the silicon substrate 1 to form a pn junction. Two types of layers are formed as the n-type impurity diffusion layer. That is, a high resistance diffusion layer (low concentration impurity diffusion layer) 6 in which n-type impurities are diffused at a low concentration is formed on the surface layer portion of the minute irregularities 5. Further, a low resistance diffusion layer (high concentration impurity diffusion layer) 2 in which n-type impurities are diffused at a high concentration is formed on the surface layer portion of the region where the minute unevenness 5 is not formed on the light receiving surface side of the silicon substrate 1. Is formed. Therefore, if the electric resistance value of the high resistance diffusion layer 6 is the first electric resistance value and the electric resistance value of the low resistance diffusion layer 2 is the second electric resistance value, the second electric resistance value is less than the first electric resistance value. Becomes smaller.
低抵抗拡散層２上および低抵抗拡散層２に隣接する高抵抗拡散層６の一部の上には、受光面側電極１０が形成されている。すなわち、受光面側電極１０は、低抵抗拡散層２および低抵抗拡散層２に隣接する高抵抗拡散層６の一部領域の２領域にまたがって接触して、低抵抗拡散層２および低抵抗拡散層２に電気的に接続している。受光面側電極１０は、銀を含み、シリコン基板１の面内において略平行に配置された多数の細いグリッド電極と、これに直行して配置された数本の太いバス電極とを有している。
On the low resistance diffusion layer 2 and on a part of the high resistance diffusion layer 6 adjacent to the low resistance diffusion layer 2, a light receiving surface side electrode 10 is formed. That is, the light-receiving surface side electrode 10 is in contact with two regions of the low-resistance diffusion layer 2 and a partial region of the high-resistance diffusion layer 6 adjacent to the low-resistance diffusion layer 2, thereby The diffusion layer 2 is electrically connected. The light-receiving surface side electrode 10 contains silver, and has a large number of thin grid electrodes arranged substantially in parallel in the plane of the silicon substrate 1, and several thick bus electrodes arranged perpendicularly thereto. Yes.
受光面側電極１０が形成されていない高抵抗拡散層６上には、入射する光の反射を低減して光利用率を向上するための反射防止膜７が形成されている。
On the high resistance diffusion layer 6 where the light receiving surface side electrode 10 is not formed, an antireflection film 7 is formed for reducing the reflection of incident light and improving the light utilization rate.
以上のように構成された実施の形態１にかかる太陽電池セルは、受光面における受光面側電極１０の下部には電気抵抗の低い低抵抗拡散層２が厚い厚みで形成されてシリコン基板１と受光面側電極１０間の電気的抵抗（接触抵抗）を小さくし、受光面におけるそれ以外の領域には電気抵抗の高い高抵抗拡散層６が薄い厚みで形成されて電子が発生し消滅する再結合速度を小さくするように構成されたセレクティブエミッタ構造を有する。
In the solar cell according to the first embodiment configured as described above, the low resistance diffusion layer 2 having a low electrical resistance is formed with a large thickness below the light receiving surface side electrode 10 on the light receiving surface, and the silicon substrate 1 and The electrical resistance (contact resistance) between the light receiving surface side electrodes 10 is reduced, and a high resistance diffusion layer 6 having a high electrical resistance is formed with a small thickness in the other region of the light receiving surface so that electrons are generated and disappear. A selective emitter structure configured to reduce coupling speed;
この太陽電池セルにおいては、受光面側電極１０の一部が低抵抗拡散層２と接合されることにより、受光面側電極１０とシリコン基板１との導電性が良好とされる。また、この太陽電池セルにおいては、高抵抗拡散層６の表面は凹凸形状とされているため、受光面側電極１０の一部が高抵抗拡散層６と接合されることにより受光面側電極１０とシリコン基板１との接触面積が大きくなり、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上が図られている。
In this solar battery cell, a part of the light-receiving surface side electrode 10 is joined to the low-resistance diffusion layer 2 so that the conductivity between the light-receiving surface side electrode 10 and the silicon substrate 1 is good. Further, in this solar cell, since the surface of the high resistance diffusion layer 6 has an irregular shape, a part of the light receiving surface side electrode 10 is joined to the high resistance diffusion layer 6 to thereby form the light receiving surface side electrode 10. The contact area between the light receiving surface side electrode 10 and the silicon substrate 1 is reduced and the adhesion strength is improved.
シリコン基板１の受光面の面内において、低抵抗拡散層２の面積は、受光面側電極１０の形成領域よりも小とされている。低抵抗拡散層２の面積が受光面側電極１０の面積に対して４０％～８０％程度である場合にシリコン基板１との密着力が良好となる。低抵抗拡散層２の面積が受光面側電極１０の面積の４０％以下の場合は、受光面側電極１０とシリコン基板１（低抵抗拡散層２）との電気的抵抗が高くなり、導電率が低下するため電流の損失が発生する。また、低抵抗拡散層２の面積が受光面側電極１０の面積の８０％以上の場合は、受光面側電極１０とシリコン基板１（低抵抗拡散層２）との密着力が十分でなく、受光面側電極１０が剥離しやすくなる。
In the surface of the light receiving surface of the silicon substrate 1, the area of the low resistance diffusion layer 2 is smaller than the region where the light receiving surface side electrode 10 is formed. When the area of the low resistance diffusion layer 2 is about 40% to 80% with respect to the area of the light receiving surface side electrode 10, the adhesion with the silicon substrate 1 is good. When the area of the low resistance diffusion layer 2 is 40% or less of the area of the light receiving surface side electrode 10, the electrical resistance between the light receiving surface side electrode 10 and the silicon substrate 1 (low resistance diffusion layer 2) increases and the electrical conductivity is increased. Current loss occurs, resulting in a loss of current. In addition, when the area of the low resistance diffusion layer 2 is 80% or more of the area of the light receiving surface side electrode 10, the adhesion between the light receiving surface side electrode 10 and the silicon substrate 1 (low resistance diffusion layer 2) is not sufficient. The light receiving surface side electrode 10 is easily peeled off.
シリコン基板１の裏面には、裏面側電極としてアルミニウムを含むアルミニウム電極９と、銀を含む外部取り出し電極である裏面銀電極８が形成されている。シリコン基板１の裏面において、アルミニウム電極９の下部領域にはアルミニウムとシリコンとの合金層が形成され、その下部にはアルミニウムの拡散により設けられたｐ＋層であるＢＳＦ（Back Surface Field）層が形成されている（図示せず）。
On the back surface of the silicon substrate 1, an aluminum electrode 9 containing aluminum as a back surface side electrode and a back surface silver electrode 8 which is an external extraction electrode containing silver are formed. On the back surface of the silicon substrate 1, an alloy layer of aluminum and silicon is formed in a lower region of the aluminum electrode 9, and a BSF (Back Surface Field) layer, which is a p + layer provided by diffusion of aluminum, is formed in the lower portion of the aluminum electrode 9. (Not shown).
以上のように構成された実施の形態１にかかる太陽電池セルにおいては、受光面側電極１０はシリコン基板１の受光面において比較的平坦な低抵抗拡散層２と接合するとともに低抵抗拡散層２の領域からはみ出して低抵抗拡散層２よりも位置の低い高抵抗拡散層６の一部と接合して形成されている。高抵抗拡散層６の表面は凹凸形状とされているため、受光面側電極１０とシリコン基板１との接触面積が大きくなり、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上が図られている。また、受光面側電極１０と低抵抗拡散層２との接続部がこのような密着強度の大きい部分に囲まれるため、受光面側電極１０と低抵抗拡散層２との接続部の強度を高めることができ、受光面側電極１０の剥離を防止することができる。
In the solar cell according to the first embodiment configured as described above, the light-receiving surface side electrode 10 is joined to the relatively flat low-resistance diffusion layer 2 on the light-receiving surface of the silicon substrate 1 and the low-resistance diffusion layer 2. It is formed so as to be bonded to a part of the high resistance diffusion layer 6 which protrudes from the region and is positioned lower than the low resistance diffusion layer 2. Since the surface of the high resistance diffusion layer 6 has an uneven shape, the contact area between the light receiving surface side electrode 10 and the silicon substrate 1 is increased, and the contact resistance between the light receiving surface side electrode 10 and the silicon substrate 1 is reduced and adhered. The strength is improved. In addition, since the connection portion between the light receiving surface side electrode 10 and the low resistance diffusion layer 2 is surrounded by such a portion having high adhesion strength, the strength of the connection portion between the light receiving surface side electrode 10 and the low resistance diffusion layer 2 is increased. It is possible to prevent peeling of the light receiving surface side electrode 10.
したがって、実施の形態１にかかる太陽電池セルによれば、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上が図られた、光－電子変換効率および長期信頼性の高い太陽電池セルが実現されている。
Therefore, according to the solar cell according to the first embodiment, the contact resistance between the light receiving surface side electrode 10 and the silicon substrate 1 is reduced and the adhesion strength is improved, and the photoelectric conversion efficiency and long-term reliability are improved. High solar cells have been realized.
つぎに、以上のように構成された実施の形態１にかかる太陽電池セルの製造方法について図２－１～図２－７を参照して説明する。図２－１～図２－７は、実施の形態１にかかる太陽電池セルの製造方法を説明する要部断面図である。
Next, a method for manufacturing the solar cell according to the first embodiment configured as described above will be described with reference to FIGS. 2-1 to 2-7. FIGS. 2-1 to 2-7 are cross-sectional views illustrating the main part of the method for manufacturing the solar battery cell according to the first embodiment.
まず、シリコン基板１としてたとえばｐ型単結晶シリコン基板を準備し、該シリコン基板１の表面を、インゴットからスライスした時の不純物やダメージ領域などの除去を行うために熱アルカリで表面を１０μｍ厚程度エッチングし、フッ酸および純水で洗浄する(図２－１)。
First, for example, a p-type single crystal silicon substrate is prepared as the silicon substrate 1, and the surface of the silicon substrate 1 is about 10 μm thick with hot alkali in order to remove impurities and damaged areas when sliced from an ingot. Etch and clean with hydrofluoric acid and pure water (Figure 2-1).
つぎに、表面の不純物を除去したシリコン基板１を熱拡散炉へ投入し、オキシ塩化リン（ＰＯＣｌ３）ガス中で加熱する。この工程により、気相拡散法によりシリコン基板１の表面に高温でリン（Ｐ）を高濃度に拡散させて、導電型を反転させた高濃度のｎ型不純物拡散層である低抵抗拡散層２をシリコン基板１の一面側（受光面側）に形成する（図２－２）。リン（Ｐ）の拡散は、たとえば低抵抗拡散層２のシート抵抗が２０～５０Ω／□の範囲になるようにする。このとき拡散させるリン（Ｐ）の濃度は、オキシ塩化リン（ＰＯＣｌ３）ガスの濃度および雰囲気温度、加熱時間により制御することが可能である。ここでは、８５０℃で１５分の熱拡散を行い、拡散後の低抵抗拡散層２のシート抵抗を測定すると３０Ω／□となった。
Next, the silicon substrate 1 from which impurities on the surface have been removed is put into a thermal diffusion furnace and heated in phosphorus oxychloride (POCl 3) gas. By this step, the low resistance diffusion layer 2 which is a high concentration n-type impurity diffusion layer obtained by diffusing phosphorus (P) at a high concentration on the surface of the silicon substrate 1 at a high temperature by a vapor phase diffusion method and inverting the conductivity type. Is formed on one surface side (light receiving surface side) of the silicon substrate 1 (FIG. 2-2). The diffusion of phosphorus (P) is performed so that the sheet resistance of the low resistance diffusion layer 2 is in the range of 20 to 50Ω / □, for example. The concentration of phosphorus (P) diffused at this time can be controlled by the concentration of phosphorus oxychloride (POCl3) gas, the ambient temperature, and the heating time. Here, thermal diffusion was performed at 850 ° C. for 15 minutes, and the sheet resistance of the low-resistance diffusion layer 2 after diffusion was measured to be 30Ω / □.
つぎに、シリコン基板１をたとえばフッ酸（ＨＦ）に浸漬することにより、リン拡散工程においてシリコン基板１の最表面に形成されたリンガラス層を除去し、洗浄する。その後、シリコン基板１を熱酸化炉に投入し、９５０℃で１０分の熱酸化を行い、低抵抗拡散層２の表面に１００ｎｍ程度の膜厚の酸化膜３を形成する。
Next, by immersing the silicon substrate 1 in, for example, hydrofluoric acid (HF), the phosphorus glass layer formed on the outermost surface of the silicon substrate 1 in the phosphorus diffusion step is removed and washed. Thereafter, the silicon substrate 1 is put into a thermal oxidation furnace, and thermal oxidation is performed at 950 ° C. for 10 minutes to form an oxide film 3 having a thickness of about 100 nm on the surface of the low resistance diffusion layer 2.
そして、シリコン基板１の受光面となる基板面上において、後に受光面側電極が形成される受光面側電極形成領域にレジストパターン４を印刷法で形成する（図２－３）。形成するレジストパターン４は受光面側電極１０のパターンよりも面積を狭く形成する。これにより、前述したように微小凹凸５の表層部の高抵抗拡散層６の一部上にも受光面側電極１０が形成されるため、シリコン基板１と受光面側電極１０との密着強度の向上効果が得られる。
Then, a resist pattern 4 is formed by a printing method on a light receiving surface side electrode forming region where a light receiving surface side electrode will be formed later on the substrate surface that becomes the light receiving surface of the silicon substrate 1 (FIG. 2-3). The resist pattern 4 to be formed is formed to have a smaller area than the pattern of the light receiving surface side electrode 10. As a result, the light-receiving surface side electrode 10 is also formed on a part of the high resistance diffusion layer 6 on the surface layer portion of the micro unevenness 5 as described above, so that the adhesion strength between the silicon substrate 1 and the light-receiving surface side electrode 10 is improved. Improvement effect is obtained.
つぎに、レジストパターン４が形成されたシリコン基板１の受光面側を、たとえば１０００番のアルミナ砥粒を使用してブラスト加工し、酸化膜３に無数の微小な穴（微小孔）を形成する。ここで、レジストパターン４で覆われた部分の酸化膜３には、微小孔は形成されない。その後、シリコン基板１を水酸化ナトリウム溶液に浸漬してレジストパターン４を除去する。
Next, the light-receiving surface side of the silicon substrate 1 on which the resist pattern 4 is formed is blasted using, for example, 1000th alumina abrasive grains to form countless minute holes (microholes) in the oxide film 3. . Here, no minute hole is formed in the oxide film 3 in the portion covered with the resist pattern 4. Thereafter, the resist pattern 4 is removed by immersing the silicon substrate 1 in a sodium hydroxide solution.
つぎに、シリコン基板１の受光面に微小凹凸５を形成する。微小凹凸５の形成は、シリコン基板１を水酸化ナトリウムとイソプロピルアルコールとの混合溶液に浸し、酸化膜３に形成された微小孔部分を介してシリコン基板１の表面をウエットエッチングすることにより行う。このエッチングでは、たとえばシリコン基板１の表面を厚み方向において１０～２０μｍのエッチングを行い、受光面側の表面の微小凹凸５が１０μｍの深さになるまで行う。
Next, minute irregularities 5 are formed on the light receiving surface of the silicon substrate 1. The minute irregularities 5 are formed by immersing the silicon substrate 1 in a mixed solution of sodium hydroxide and isopropyl alcohol and performing wet etching on the surface of the silicon substrate 1 through the minute hole portions formed in the oxide film 3. In this etching, for example, the surface of the silicon substrate 1 is etched by 10 to 20 μm in the thickness direction until the minute unevenness 5 on the surface on the light receiving surface side becomes 10 μm deep.
この結果、シリコン基板１の受光面において、微小孔部分を介してエッチングされた部分の低抵抗拡散層２が除去される。ここで、ブラスト加工による微小孔の形成時にレジストパターン４で覆われていた部分の酸化膜３は、微小孔が形成されていないためエッチングが行われず、低抵抗拡散層２がほぼ平坦な表面状態で残存する。その後、シリコン基板１をフッ酸に浸漬して酸化膜３を除去する（図２－４）。このエッチング処理により、低抵抗拡散層２は、シリコン基板１の受光面において突出した受光面側電極形成領域のみに残存する。
As a result, on the light receiving surface of the silicon substrate 1, the portion of the low-resistance diffusion layer 2 etched through the microhole portion is removed. Here, the oxide film 3 in the portion covered with the resist pattern 4 at the time of forming the microhole by blasting is not etched because the microhole is not formed, and the low resistance diffusion layer 2 has a substantially flat surface state. Remains at. Thereafter, the silicon substrate 1 is immersed in hydrofluoric acid to remove the oxide film 3 (FIGS. 2-4). By this etching process, the low resistance diffusion layer 2 remains only in the light receiving surface side electrode forming region protruding from the light receiving surface of the silicon substrate 1.
つぎに、表面に微小凹凸５を形成したシリコン基板１を再度熱拡散炉へ投入し、オキシ塩化リン（ＰＯＣｌ３）ガス中で加熱する。この工程により、気相拡散法によりシリコン基板１の表面に高温でリン（Ｐ）を低濃度に拡散させて、導電型を反転させた低濃度のｎ型不純物拡散層である高抵抗拡散層６を微小凹凸５の表層に形成する（図２－５）。リン（Ｐ）の拡散は、たとえば高抵抗拡散層６のシート抵抗が８０～１２０Ω／□の範囲になるようにする。このとき拡散させるリン（Ｐ）の濃度は、オキシ塩化リン（ＰＯＣｌ３）ガスの濃度および雰囲気温度、加熱時間により制御することが可能である。ここでは、８００℃で１０分の熱拡散を行い、拡散後の高抵抗拡散層６のシート抵抗を測定すると１００Ω／□となった。
Next, the silicon substrate 1 having the minute irregularities 5 formed on the surface is again put into a thermal diffusion furnace and heated in phosphorus oxychloride (POCl3) gas. Through this process, phosphorus (P) is diffused at a high temperature on the surface of the silicon substrate 1 by a vapor phase diffusion method at a low concentration, and the high resistance diffusion layer 6 is a low concentration n-type impurity diffusion layer in which the conductivity type is inverted. Is formed on the surface layer of the minute irregularities 5 (FIG. 2-5). The diffusion of phosphorus (P) is performed so that the sheet resistance of the high resistance diffusion layer 6 is in the range of 80 to 120 Ω / □, for example. The concentration of phosphorus (P) diffused at this time can be controlled by the concentration of phosphorus oxychloride (POCl3) gas, the ambient temperature, and the heating time. Here, thermal diffusion was performed at 800 ° C. for 10 minutes, and the sheet resistance of the high-resistance diffusion layer 6 after diffusion was measured to be 100Ω / □.
つぎに、高抵抗拡散層６上に反射防止膜７を形成する。反射防止膜７としては、たとえばシランとアンモニアとの混合ガスを用いたプラズマＣＶＤ法により膜厚６０ｎｍ～８０ｎｍの窒化シリコン膜を形成する（図２－６）。なお、反射防止膜７は、シリコン基板１の受光面に形成してもよい。
Next, an antireflection film 7 is formed on the high resistance diffusion layer 6. As the antireflection film 7, a silicon nitride film with a film thickness of 60 nm to 80 nm is formed by, for example, a plasma CVD method using a mixed gas of silane and ammonia (FIG. 2-6). The antireflection film 7 may be formed on the light receiving surface of the silicon substrate 1.
つぎに、表裏面の電極を形成する。電極の形成は、電極ペーストを印刷法により電極のパターンに印刷し、乾燥、焼成することにより行う。電極ペーストの印刷は、電極パターンに対応した開口部を有する樹脂膜が金属メッシュ上に形成された印刷マスクに、銀粒子またはアルミニウム粒子を含む電極ペーストをスキイジで押し込み、電極ペーストをマスクの開口部から透過させて行う。
Next, the front and back electrodes are formed. The electrodes are formed by printing an electrode paste on an electrode pattern by a printing method, drying, and firing. The electrode paste is printed by pressing the electrode paste containing silver particles or aluminum particles with a squeegee into a printing mask in which a resin film having an opening corresponding to the electrode pattern is formed on the metal mesh, and the electrode paste is opened in the mask. To make it transparent.
まず、銀粒子を含む電極ペーストを、外部との導通を取る外部取り出し電極である裏面銀電極８のパターンにシリコン基板１の裏面に印刷、乾燥する。つぎに、アルミニウム粒子を含む電極ペーストを、裏面銀電極８のパターンを除いたアルミニウム電極９のパターンにシリコン基板１の裏面に印刷する。つぎに、銀粒子を含む電極ペーストを、受光面側電極１０のパターンにシリコン基板１の受光面側に印刷する。ここで、受光面側電極１０のパターンの印刷は、シリコン基板１の受光面側に形成した低抵抗拡散層２に位置を合わせて行う。
First, an electrode paste containing silver particles is printed and dried on the back surface of the silicon substrate 1 in a pattern of the back surface silver electrode 8 which is an external take-out electrode that conducts with the outside. Next, an electrode paste containing aluminum particles is printed on the back surface of the silicon substrate 1 in a pattern of the aluminum electrode 9 excluding the pattern of the back surface silver electrode 8. Next, an electrode paste containing silver particles is printed on the light receiving surface side of the silicon substrate 1 in a pattern of the light receiving surface side electrode 10. Here, the pattern of the light receiving surface side electrode 10 is printed in alignment with the low resistance diffusion layer 2 formed on the light receiving surface side of the silicon substrate 1.
印刷の位置合わせは、たとえば先のレジストパターン４の印刷時に、印刷マスクに２点もしくはそれ以上の位置合わせマーカーを形成しておく。そして、受光面側電極１０の印刷用の印刷マスクにもこれと同じ位置に位置合わせマーカーを形成するようにマスクを形成する。そして、この位置合わせマーカーの位置がレジストで形成したマーカーと一致するように手動で受光面側電極１０の印刷用の印刷マスクの位置を調整する。また、画像処理装置でシリコン基板１の受光面側の画像を取り込み、低抵抗拡散層２のパターンに受光面側電極１０の印刷位置を一致させることで精度の高い位置合わせが可能である。
For printing alignment, for example, at the time of printing the previous resist pattern 4, two or more alignment markers are formed on the printing mask. Then, a mask is formed on the print mask for printing on the light receiving surface side electrode 10 so that the alignment marker is formed at the same position. Then, the position of the printing mask for printing on the light-receiving surface side electrode 10 is manually adjusted so that the position of the alignment marker coincides with the marker formed of the resist. In addition, the image processing apparatus captures an image on the light receiving surface side of the silicon substrate 1 and aligns the printing position of the light receiving surface side electrode 10 with the pattern of the low-resistance diffusion layer 2 so that highly accurate alignment is possible.
そして、印刷した電極ペーストを乾燥させた後、電極ペーストを焼成する。これにより、低抵抗拡散層２上および低抵抗拡散層２に隣接する高抵抗拡散層６の一部の上には、受光面側電極１０が形成される。また、シリコン基板１の裏面には、裏面側電極としてアルミニウム電極９と裏面銀電極８が形成される。なお、低抵抗拡散層２上および高抵抗拡散層６上に反射防止膜７が形成されている部分では、いわゆるファイヤースルーにより受光面側電極１０が低抵抗拡散層２および高抵抗拡散層６に接続し、導通する（図２－７）。
Then, after drying the printed electrode paste, the electrode paste is baked. Thereby, the light receiving surface side electrode 10 is formed on the low resistance diffusion layer 2 and on a part of the high resistance diffusion layer 6 adjacent to the low resistance diffusion layer 2. Further, an aluminum electrode 9 and a back surface silver electrode 8 are formed on the back surface of the silicon substrate 1 as back surface side electrodes. In the portion where the antireflection film 7 is formed on the low resistance diffusion layer 2 and the high resistance diffusion layer 6, the light receiving surface side electrode 10 is formed on the low resistance diffusion layer 2 and the high resistance diffusion layer 6 by so-called fire-through. Connect and conduct (Figure 2-7). *
以上の工程を実施することにより、図１－１および図１－２に示す実施の形態１にかかる太陽電池セルが得られる。
By performing the above steps, the solar battery cell according to Embodiment 1 shown in FIGS. 1-1 and 1-2 is obtained.
以上のような実施の形態１にかかる太陽電池セルの製造方法においては、シリコン基板１の受光面の面内において、受光面側電極１０は、比較的平坦な低抵抗拡散層２を覆ってこれに接合されるとともに、低抵抗拡散層２の領域からはみ出して該低抵抗拡散層２よりも位置の低い高抵抗拡散層６の一部を覆ってこれに接合されて形成される。すなわち、受光面側電極１０は、低抵抗拡散層２とこの低抵抗拡散層２に隣接する領域の高抵抗拡散層６の一部を覆って形成される。
In the solar cell manufacturing method according to the first embodiment as described above, the light receiving surface side electrode 10 covers the relatively flat low resistance diffusion layer 2 in the surface of the light receiving surface of the silicon substrate 1. And a part of the high resistance diffusion layer 6 that protrudes from the region of the low resistance diffusion layer 2 and is lower in position than the low resistance diffusion layer 2 and is bonded to the low resistance diffusion layer 2. That is, the light-receiving surface side electrode 10 is formed so as to cover a part of the low resistance diffusion layer 2 and the high resistance diffusion layer 6 in a region adjacent to the low resistance diffusion layer 2.
高抵抗拡散層６の表面は凹凸形状とされるため、受光面側電極１０とシリコン基板１との接触面積が大きくなり、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上が図れる。また、受光面側電極１０と低抵抗拡散層２との接続部がこのような密着強度の大きい部分に囲まれるため、受光面側電極１０と低抵抗拡散層２との接続部の強度を高めることができ、受光面側電極１０の剥離を防止することができる。
Since the surface of the high resistance diffusion layer 6 has an uneven shape, the contact area between the light receiving surface side electrode 10 and the silicon substrate 1 is increased, the contact resistance between the light receiving surface side electrode 10 and the silicon substrate 1 is reduced, and the adhesion strength is increased. Can be improved. In addition, since the connection portion between the light receiving surface side electrode 10 and the low resistance diffusion layer 2 is surrounded by such a portion having high adhesion strength, the strength of the connection portion between the light receiving surface side electrode 10 and the low resistance diffusion layer 2 is increased. It is possible to prevent peeling of the light receiving surface side electrode 10.
したがって、実施の形態１にかかる太陽電池セルの製造方法によれば、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上を図り、光－電子変換効率および長期信頼性の高い太陽電池セルを実現することができる。
Therefore, according to the method for manufacturing the solar cell according to the first embodiment, the contact resistance between the light receiving surface side electrode 10 and the silicon substrate 1 is reduced and the adhesion strength is improved, and the photoelectric conversion efficiency and long-term reliability are improved. High solar cells can be realized.
なお、上述した実施の形態１にかかる太陽電池セルの製造方法において、低抵抗拡散層２の形成前にシリコン基板１の受光面側の表面をエッチングして所定の大きさの凹凸形状を設けてもよい。その後に低抵抗拡散層２を形成することにより、低抵抗拡散層２の表面にも凹凸形状が形成されるため、受光面側電極１０とシリコン基板１との接触面積が大きくなり、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上が図れる。
In the method for manufacturing the solar cell according to the first embodiment described above, the surface on the light receiving surface side of the silicon substrate 1 is etched to form a concavo-convex shape of a predetermined size before the low resistance diffusion layer 2 is formed. Also good. By forming the low resistance diffusion layer 2 after that, an uneven shape is also formed on the surface of the low resistance diffusion layer 2, so that the contact area between the light receiving surface side electrode 10 and the silicon substrate 1 increases, and the light receiving surface side The contact resistance between the electrode 10 and the silicon substrate 1 can be reduced and the adhesion strength can be improved.
実施の形態２．
実施の形態２では、低抵抗拡散層２の形状について説明する。前述したように低抵抗拡散層２の面積を受光面側電極１０の形成領域の面積よりも小とするには、たとえば低抵抗拡散層２の幅を狭くする、低抵抗拡散層２の形状を破線形状にする、低抵抗拡散層の形状を複数ライン形状にする、など低抵抗拡散層２の形状を変更する方法が考えられる。Embodiment 2. FIG.
In the second embodiment, the shape of the lowresistance diffusion layer 2 will be described. As described above, in order to make the area of the low resistance diffusion layer 2 smaller than the area of the region where the light receiving surface side electrode 10 is formed, for example, the width of the low resistance diffusion layer 2 is narrowed. A method of changing the shape of the low resistance diffusion layer 2 such as a broken line shape or a shape of the low resistance diffusion layer having a plurality of lines is conceivable.
実施の形態２では、低抵抗拡散層２の形状について説明する。前述したように低抵抗拡散層２の面積を受光面側電極１０の形成領域の面積よりも小とするには、たとえば低抵抗拡散層２の幅を狭くする、低抵抗拡散層２の形状を破線形状にする、低抵抗拡散層の形状を複数ライン形状にする、など低抵抗拡散層２の形状を変更する方法が考えられる。
In the second embodiment, the shape of the low
図３は、低抵抗拡散層２の形状の一例を示す太陽電池セルの受光面側の要部平面図である。図３においては、反射防止膜７および受光面側電極１０を透過して見ている。図３は低抵抗拡散層２の形状をメッシュ形状に形成した例を示している。低抵抗拡散層２の形状をメッシュ形状にすることで、受光面の面方向において均等に凹凸部を形成することができ、受光面側電極１０とシリコン基板１との間の密着力を面内において均等に増強することができる。これにより、受光面側電極１０とシリコン基板１との間の全体の密着強度が向上し、受光面側電極１０とシリコン基板１との間でより強い密着力を得ることが可能である。
FIG. 3 is a plan view of a main part on the light receiving surface side of the solar battery cell showing an example of the shape of the low resistance diffusion layer 2. In FIG. 3, the antireflection film 7 and the light receiving surface side electrode 10 are seen through. FIG. 3 shows an example in which the low resistance diffusion layer 2 is formed in a mesh shape. By forming the low resistance diffusion layer 2 in a mesh shape, uneven portions can be formed evenly in the surface direction of the light receiving surface, and the adhesion between the light receiving surface side electrode 10 and the silicon substrate 1 is in-plane. Can be evenly enhanced. As a result, the overall adhesion strength between the light receiving surface side electrode 10 and the silicon substrate 1 is improved, and a stronger adhesion force can be obtained between the light receiving surface side electrode 10 and the silicon substrate 1.
実施の形態３．
実施の形態２で述べたように、低抵抗拡散層２に部分的に凹凸を設けることにより、低抵抗拡散層２と受光面側電極１０との間でより強い密着力を得ることができる。低抵抗拡散層２に部分的に凹凸を設けるには、たとえばレジストパターン４で覆われた酸化膜３（電極形成領域）にブラスト痕を部分的に付けてエッチングする。Embodiment 3 FIG.
As described in the second embodiment, it is possible to obtain stronger adhesion between the low-resistance diffusion layer 2 and the light-receiving surface side electrode 10 by partially providing irregularities in the low-resistance diffusion layer 2. In order to partially provide unevenness in the low-resistance diffusion layer 2, for example, a blast mark is partially formed on the oxide film 3 (electrode formation region) covered with the resist pattern 4 and etched.
実施の形態２で述べたように、低抵抗拡散層２に部分的に凹凸を設けることにより、低抵抗拡散層２と受光面側電極１０との間でより強い密着力を得ることができる。低抵抗拡散層２に部分的に凹凸を設けるには、たとえばレジストパターン４で覆われた酸化膜３（電極形成領域）にブラスト痕を部分的に付けてエッチングする。
As described in the second embodiment, it is possible to obtain stronger adhesion between the low-
印刷法によるレジストパターン４の形成では、たとえば２９０メッシュ、乳剤厚１５μｍの条件の印刷マスクを用いてレジスト材料を印刷すると、膜厚１２μｍのレジスト膜が形成される。このような膜からなるレジストパターン４に１０００番のアルミナ砥粒、圧力０．２５Ｐａでブラスト処理すると、レジストパターン４で覆われた酸化膜３（電極形成領域）にはブラスト痕は残らない。
In the formation of the resist pattern 4 by the printing method, for example, when a resist material is printed using a printing mask under the conditions of 290 mesh and an emulsion thickness of 15 μm, a resist film with a thickness of 12 μm is formed. When the resist pattern 4 made of such a film is blasted with No. 1000 alumina abrasive grains and a pressure of 0.25 Pa, no blast marks remain on the oxide film 3 (electrode formation region) covered with the resist pattern 4.
ここで、ブラスト圧力を変えると微小凹凸５の形成状態が変わるので好ましくない。このため、印刷膜厚を薄くすることが好ましい。たとえば４００メッシュ、乳剤厚３μｍの条件の印刷マスクを用いることで、レジスト膜の膜厚は８μｍになる。このようなレジストパターン４を酸化膜３上に形成して前記ブラスト条件でブラスト加工を行うと、レジストパターン４で覆われた酸化膜３（電極形成領域）にも部分的に微小孔が形成される。この状態で実施の形態１の場合と同様に微小孔を介してシリコン基板１の受光面のエッチングを行うと、レジストパターン４で覆われていた領域の酸化膜３（電極形成領域）にも微小凹凸が形成される。
Here, changing the blast pressure is not preferable because the formation state of the minute irregularities 5 changes. For this reason, it is preferable to reduce the printed film thickness. For example, by using a printing mask under the conditions of 400 mesh and emulsion thickness of 3 μm, the thickness of the resist film becomes 8 μm. When such a resist pattern 4 is formed on the oxide film 3 and blasting is performed under the blasting conditions, micro holes are partially formed in the oxide film 3 (electrode formation region) covered with the resist pattern 4. The In this state, when the light receiving surface of the silicon substrate 1 is etched through the micro holes as in the case of the first embodiment, the oxide film 3 (electrode formation region) in the region covered with the resist pattern 4 is also microscopic. Unevenness is formed.
これにより、低抵抗拡散層２の表面に部分的に凹凸を設けることができ、低抵抗拡散層２と受光面側電極１０との間でより強い密着強度を得ることができる。なお、この凹凸は、低抵抗拡散層２の表面における全面に設けてもよい。また、この凹凸は、低抵抗拡散層２の表面における一分的に設けられ、残りの部分が平坦とされてもよい。
Thereby, unevenness can be partially provided on the surface of the low resistance diffusion layer 2, and a stronger adhesion strength can be obtained between the low resistance diffusion layer 2 and the light receiving surface side electrode 10. The unevenness may be provided on the entire surface of the low resistance diffusion layer 2. Moreover, this unevenness | corrugation may be provided in part in the surface of the low resistance diffusion layer 2, and the remaining part may be made flat.
実施の形態４．
シリコン基板１と受光面側電極１０のうちの細いグリッド電極との密着強度を上げるためには、たとえば図４に示すようにレジストパターン４を電流が多く流れるバス電極に対応した形状にのみ形成し、バス電極に対応した形状の低抵抗拡散層２ａを形成する方法がある。この場合、グリッド電極は表面状態が凹凸形状とされた高抵抗拡散層６上に形成されるため、シリコン基板１とグリッド電極との密着強度を向上させることができる。図４は、低抵抗拡散層２の形状の一例を示す太陽電池セルの受光面側の要部平面図である。Embodiment 4 FIG.
In order to increase the adhesion strength between thesilicon substrate 1 and the thin grid electrode of the light receiving surface side electrode 10, for example, as shown in FIG. There is a method of forming the low resistance diffusion layer 2a having a shape corresponding to the bus electrode. In this case, since the grid electrode is formed on the high resistance diffusion layer 6 whose surface state is uneven, the adhesion strength between the silicon substrate 1 and the grid electrode can be improved. FIG. 4 is a plan view of a main part on the light receiving surface side of the solar battery cell showing an example of the shape of the low resistance diffusion layer 2.
シリコン基板１と受光面側電極１０のうちの細いグリッド電極との密着強度を上げるためには、たとえば図４に示すようにレジストパターン４を電流が多く流れるバス電極に対応した形状にのみ形成し、バス電極に対応した形状の低抵抗拡散層２ａを形成する方法がある。この場合、グリッド電極は表面状態が凹凸形状とされた高抵抗拡散層６上に形成されるため、シリコン基板１とグリッド電極との密着強度を向上させることができる。図４は、低抵抗拡散層２の形状の一例を示す太陽電池セルの受光面側の要部平面図である。
In order to increase the adhesion strength between the
ただし、この場合はグリッド電極を高抵抗拡散層６上に形成することになるので、電流の抵抗が大きくなり特性を劣化させてしまう原因になる恐れがある。そこで、このときの高抵抗拡散層６のシート抵抗を６０～１００Ω／□にすることで、電流の流れを妨げることなくグリッド電極とシリコン基板１との密着強度を向上させることができる。
However, in this case, since the grid electrode is formed on the high resistance diffusion layer 6, there is a possibility that the resistance of the current increases and the characteristics are deteriorated. Therefore, by setting the sheet resistance of the high resistance diffusion layer 6 at this time to 60 to 100Ω / □, the adhesion strength between the grid electrode and the silicon substrate 1 can be improved without hindering the flow of current.
実施の形態５．
実施の形態５では低抵抗拡散層の形状を変更した変形例について説明する。実施の形態１で説明したように、低抵抗拡散層２と受光面側電極１０とはともに印刷法によりパターンを形成している。しかし、それぞれのパターン再現性または位置合わせ精度が低いと、図５に示すように受光面側電極１０が低抵抗拡散層２を覆わない部分が発生する。この場合は、低抵抗拡散層２と受光面側電極１０との接触面積を大きくする効果が十分に得られないため接触抵抗の低減効果を十分に得られない。その結果、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上の効果が十分に得られない。図５は、低抵抗拡散層２と受光面側電極１０との位置関係の一例を示す太陽電池セルの受光面側の要部平面図である。Embodiment 5. FIG.
In the fifth embodiment, a modified example in which the shape of the low resistance diffusion layer is changed will be described. As described in the first embodiment, the lowresistance diffusion layer 2 and the light receiving surface side electrode 10 both form a pattern by a printing method. However, if the pattern reproducibility or alignment accuracy is low, a portion where the light receiving surface side electrode 10 does not cover the low resistance diffusion layer 2 is generated as shown in FIG. In this case, the effect of increasing the contact area between the low-resistance diffusion layer 2 and the light-receiving surface side electrode 10 cannot be sufficiently obtained, so that the effect of reducing the contact resistance cannot be sufficiently obtained. As a result, the effect of lowering the contact resistance between the light receiving surface side electrode 10 and the silicon substrate 1 and improving the adhesion strength cannot be obtained sufficiently. FIG. 5 is a plan view of a principal part on the light receiving surface side of the solar battery cell showing an example of the positional relationship between the low resistance diffusion layer 2 and the light receiving surface side electrode 10.
実施の形態５では低抵抗拡散層の形状を変更した変形例について説明する。実施の形態１で説明したように、低抵抗拡散層２と受光面側電極１０とはともに印刷法によりパターンを形成している。しかし、それぞれのパターン再現性または位置合わせ精度が低いと、図５に示すように受光面側電極１０が低抵抗拡散層２を覆わない部分が発生する。この場合は、低抵抗拡散層２と受光面側電極１０との接触面積を大きくする効果が十分に得られないため接触抵抗の低減効果を十分に得られない。その結果、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上の効果が十分に得られない。図５は、低抵抗拡散層２と受光面側電極１０との位置関係の一例を示す太陽電池セルの受光面側の要部平面図である。
In the fifth embodiment, a modified example in which the shape of the low resistance diffusion layer is changed will be described. As described in the first embodiment, the low
そこで、本実施の形態では、図６に示すように延在方向（長手方向）において輪郭（外形形状）が蛇行した低抵抗拡散層２１を形成する。図６は、実施の形態５にかかる低抵抗拡散層２１と受光面側電極１０との位置関係の一例を示す太陽電池セルの受光面側の要部平面図である。図６では、低抵抗拡散層２１と受光面側電極１０との間の位置関係が想定した標準の位置関係にある場合を示している。これにより、例えば図７に示すように、低抵抗拡散層２１と受光面側電極１０との間の位置関係が想定した標準の位置関係（図６参照）からズレて位置ズレが生じても、低抵抗拡散層２１と受光面側電極１０との接触面積はこれらが標準の位置関係にある場合（図６参照）と同等とすることが可能であり、受光面側電極１０とシリコン基板１との間で低い接触抵抗および強い密着強度を維持可能である。図７は、実施の形態５にかかる低抵抗拡散層２１と受光面側電極１０との位置関係の一例を示す太陽電池セルの受光面側の要部平面図である。図７では、低抵抗拡散層２１と受光面側電極１０との間に位置ズレが生じた場合を示している。
Therefore, in the present embodiment, as shown in FIG. 6, the low resistance diffusion layer 21 whose outline (outer shape) meanders in the extending direction (longitudinal direction) is formed. FIG. 6 is a plan view of a principal part on the light receiving surface side of the solar battery cell showing an example of the positional relationship between the low resistance diffusion layer 21 and the light receiving surface side electrode 10 according to the fifth embodiment. FIG. 6 shows a case where the positional relationship between the low resistance diffusion layer 21 and the light receiving surface side electrode 10 is a standard positional relationship assumed. Thereby, for example, as shown in FIG. 7, even if the positional deviation occurs from the standard positional relation (see FIG. 6) assumed as the positional relation between the low resistance diffusion layer 21 and the light receiving surface side electrode 10, The contact area between the low-resistance diffusion layer 21 and the light-receiving surface side electrode 10 can be made equal to the case where these are in a standard positional relationship (see FIG. 6). Low contact resistance and strong adhesion strength can be maintained. FIG. 7 is a plan view of a principal part on the light receiving surface side of the solar battery cell showing an example of the positional relationship between the low resistance diffusion layer 21 and the light receiving surface side electrode 10 according to the fifth embodiment. FIG. 7 shows a case where a positional deviation occurs between the low resistance diffusion layer 21 and the light receiving surface side electrode 10.
図７に示すように、高抵抗拡散層６のうち、低抵抗拡散層２１の幅方向において低抵抗拡散層２１に隣接して部分的に低抵抗拡散層２１側に膨らんだ領域は、受光面側電極１０に当接して受光面側電極１０で覆われる。これにより、高抵抗拡散層６と受光面側電極１０との接触面積が大きくなり、受光面側電極１０とシリコン基板１との間で強い密着強度を維持可能である。
As shown in FIG. 7, in the high resistance diffusion layer 6, a region that swells partially toward the low resistance diffusion layer 21 adjacent to the low resistance diffusion layer 21 in the width direction of the low resistance diffusion layer 21 is a light receiving surface. It is in contact with the side electrode 10 and is covered with the light receiving surface side electrode 10. As a result, the contact area between the high-resistance diffusion layer 6 and the light-receiving surface side electrode 10 is increased, and strong adhesion strength can be maintained between the light-receiving surface side electrode 10 and the silicon substrate 1.
また、低抵抗拡散層２１のうち、低抵抗拡散層２１の幅方向において高抵抗拡散層６に隣接して部分的に高抵抗拡散層６側に膨らんだ領域の端部近傍は、受光面側電極１０で覆われない。しかしながら、全体としては低抵抗拡散層２１のうち図６に示した場合と同等の面積が受光面側電極１０で覆われるため低抵抗拡散層２１と受光面側電極１０との接触面積が大きく、受光面側電極１０とシリコン基板１との間で低い接触抵抗を維持可能である。
Further, in the low resistance diffusion layer 21, the vicinity of the end portion of the region that swells to the high resistance diffusion layer 6 side adjacent to the high resistance diffusion layer 6 in the width direction of the low resistance diffusion layer 21 is on the light receiving surface side. It is not covered with the electrode 10. However, as a whole, an area equivalent to the case shown in FIG. 6 of the low resistance diffusion layer 21 is covered with the light receiving surface side electrode 10, so that the contact area between the low resistance diffusion layer 21 and the light receiving surface side electrode 10 is large. A low contact resistance can be maintained between the light receiving surface side electrode 10 and the silicon substrate 1.
したがって、上述した実施の形態１～実施の形態４において、低抵抗拡散層の外形形状を延在方向（長手方向）において蛇行させることにより、低抵抗拡散層２１と受光面側電極１０との間の位置ズレが生じた場合でも、受光面側電極１０とシリコン基板１との接触抵抗の低下および密着強度の向上が図られた、光－電子変換効率および長期信頼性の高い太陽電池セルが実現可能である。
Therefore, in the first to fourth embodiments described above, the outer shape of the low resistance diffusion layer is meandered in the extending direction (longitudinal direction), whereby the low resistance diffusion layer 21 and the light receiving surface side electrode 10 are interposed. Even if the misalignment occurs, a photovoltaic cell with high photo-electron conversion efficiency and long-term reliability is realized in which the contact resistance between the light receiving surface side electrode 10 and the silicon substrate 1 is reduced and the adhesion strength is improved. Is possible.
また、上記の実施の形態で説明した構成を有する太陽電池セルを複数形成し、隣接する太陽電池セル同士を直列または並列に電気的に接続することにより、良好な光閉じ込め効果を有し、光電変換効率に優れた太陽電池モジュールが実現できる。この場合は、たとえば隣接する太陽電池セルの一方の受光面側電極１０と他方の裏面銀電極８とを電気的に接続すればよい。
In addition, by forming a plurality of solar cells having the configuration described in the above embodiment and electrically connecting adjacent solar cells in series or in parallel, it has a good light confinement effect, A solar cell module excellent in conversion efficiency can be realized. In this case, for example, one light receiving surface side electrode 10 and the other back surface silver electrode 8 of adjacent solar cells may be electrically connected.
以上のように、本発明にかかる太陽電池は、光－電子変換効率および長期信頼性に優れた太陽電池の実現に有用である。
As described above, the solar cell according to the present invention is useful for realizing a solar cell excellent in photo-electron conversion efficiency and long-term reliability.
１ 半導体基板（シリコン基板）
２ 低抵抗拡散層（高濃度不純物拡散層）
２ａ 低抵抗拡散層
３ 酸化膜
４ レジストパターン
５ 微小凹凸
６ 高抵抗拡散層（低濃度不純物拡散層）
７ 反射防止膜
８ 裏面銀電極
９ アルミニウム電極
１０ 受光面側電極
２１ 輪郭が蛇行した低抵抗拡散層 1 Semiconductor substrate (silicon substrate)
2 Low resistance diffusion layer (High concentration impurity diffusion layer)
2a Lowresistance diffusion layer 3 Oxide film 4 Resist pattern 5 Micro unevenness 6 High resistance diffusion layer (low concentration impurity diffusion layer)
7Antireflection film 8 Back surface silver electrode 9 Aluminum electrode 10 Light receiving surface side electrode 21 Low resistance diffusion layer with meandering outline
２ 低抵抗拡散層（高濃度不純物拡散層）
２ａ 低抵抗拡散層
３ 酸化膜
４ レジストパターン
５ 微小凹凸
６ 高抵抗拡散層（低濃度不純物拡散層）
７ 反射防止膜
８ 裏面銀電極
９ アルミニウム電極
１０ 受光面側電極
２１ 輪郭が蛇行した低抵抗拡散層 1 Semiconductor substrate (silicon substrate)
2 Low resistance diffusion layer (High concentration impurity diffusion layer)
2a Low
7
Claims (16)
- ２種類の異なる電気抵抗値を有する第２導電型の不純物拡散層が受光面側に設けられた第１導電型の半導体基板と、前記半導体基板の受光面側に設けられた受光面側電極と、前記半導体基板の裏面側に設けられた裏面側電極とを備え、
前記第２導電型の不純物拡散層が、表面が凹凸形状とされた第１不純物拡散層と、前記第１不純物拡散層よりも小さい電気抵抗値を有する第２不純物拡散層とを備える太陽電池において、
前記受光面側電極が、前記第２不純物拡散層の領域および前記第２不純物拡散層に隣接する前記第１不純物拡散層の一部領域の２領域にまたがって接触して前記第１不純物拡散層および前記第２不純物拡散層に電気的に接続して設けられること、
を特徴とする太陽電池。 A first conductivity type semiconductor substrate provided with a second conductivity type impurity diffusion layer having two different electrical resistance values on the light receiving surface side; and a light receiving surface side electrode provided on the light receiving surface side of the semiconductor substrate; A back side electrode provided on the back side of the semiconductor substrate,
In the solar cell, the second conductivity type impurity diffusion layer includes a first impurity diffusion layer having an uneven surface and a second impurity diffusion layer having an electric resistance value smaller than that of the first impurity diffusion layer. ,
The light-receiving surface side electrode is in contact with two regions of the second impurity diffusion layer and a partial region of the first impurity diffusion layer adjacent to the second impurity diffusion layer, and the first impurity diffusion layer And being electrically connected to the second impurity diffusion layer,
A solar cell characterized by. - 前記半導体基板の面内において前記第２不純物拡散層の面積が前記受光面側電極の面積よりも小であり、
前記受光面側電極が、前記第２不純物拡散層の全ての領域を覆って設けられること、
を特徴とする請求項１に記載の太陽電池。 An area of the second impurity diffusion layer in the plane of the semiconductor substrate is smaller than an area of the light receiving surface side electrode;
The light-receiving surface side electrode is provided to cover the entire region of the second impurity diffusion layer;
The solar cell according to claim 1. - 前記第２不純物拡散層の表面が平坦とされること、
を特徴とする請求項１または２に記載の太陽電池。 The surface of the second impurity diffusion layer is flat;
The solar cell according to claim 1, wherein: - 前記第２不純物拡散層の表面が少なくとも部分的に凹凸形状とされること、
を特徴とする請求項１または２に記載の太陽電池。 The surface of the second impurity diffusion layer is at least partially uneven,
The solar cell according to claim 1, wherein: - 前記第２不純物拡散層がメッシュパターンで形成されること、
を特徴とする請求項４に記載の太陽電池。 The second impurity diffusion layer is formed in a mesh pattern;
The solar cell according to claim 4. - 前記受光面側電極が、細線形状を有するグリッド電極と、前記グリッド電極より太幅形状を有して前記グリッド電極に接続するバス電極とからなり、
前記バス電極に覆われる領域のみに前記第２不純物拡散層が形成されること、
を特徴とする請求項１～５のいずれか１つに記載の太陽電池。 The light-receiving surface side electrode is composed of a grid electrode having a thin line shape, and a bus electrode having a shape wider than the grid electrode and connected to the grid electrode,
The second impurity diffusion layer is formed only in a region covered with the bus electrode;
The solar cell according to any one of claims 1 to 5, wherein: - 前記第２不純物拡散層の輪郭が、前記第２不純物拡散層の延在方向において蛇行した形状を呈し、
前記第１不純物拡散層のうち、前記第２不純物拡散層の幅方向において前記第２不純物拡散層に隣接して部分的に前記第２不純物拡散層側に膨らんだ領域は、前記受光面側電極に当接して前記受光面側電極で覆われ、
前記第２不純物拡散層のうち、前記第２不純物拡散層の幅方向において前記第１不純物拡散層に隣接して部分的に前記第１不純物拡散層側に膨らんだ領域の端部近傍は、前記受光面側電極で覆われないこと、
を特徴とする請求項１～６のいずれか１つに記載の太陽電池。 The outline of the second impurity diffusion layer has a meandering shape in the extending direction of the second impurity diffusion layer,
Of the first impurity diffusion layer, a region that swells partially toward the second impurity diffusion layer adjacent to the second impurity diffusion layer in the width direction of the second impurity diffusion layer is the light receiving surface side electrode. And is covered with the light receiving surface side electrode,
Of the second impurity diffusion layer, in the width direction of the second impurity diffusion layer, adjacent to the first impurity diffusion layer, the vicinity of the end of the region partially bulging toward the first impurity diffusion layer is Do not cover with the electrode on the light-receiving surface side,
The solar cell according to any one of claims 1 to 6, wherein: - 第１導電型の半導体基板の一面側に、表面が凹凸形状とされた第１不純物拡散層と、表面が平坦とされて前記第１不純物拡散層よりも小さい電気抵抗値を有する第２不純物拡散層とを形成する不純物拡散層形成工程と、
前記第２不純物拡散層の領域および前記第２不純物拡散層に隣接する前記第１不純物拡散層の一部領域の２領域にまたがって接触して前記第１不純物拡散層および前記第２不純物拡散層に電気的に接続する受光面側電極を前記半導体基板の一面側に形成する受光面側電極形成工程と、
前記半導体基板の裏面側に裏面側電極を形成する裏面側電極形成工程と、
を含むことを特徴とする太陽電池の製造方法。 A first impurity diffusion layer having a concavo-convex surface on the one surface side of the first conductivity type semiconductor substrate, and a second impurity diffusion having a flat surface and a smaller electric resistance than the first impurity diffusion layer. An impurity diffusion layer forming step of forming a layer;
The first impurity diffusion layer and the second impurity diffusion layer in contact with two regions of the region of the second impurity diffusion layer and a partial region of the first impurity diffusion layer adjacent to the second impurity diffusion layer. A light receiving surface side electrode forming step of forming a light receiving surface side electrode electrically connected to the one surface side of the semiconductor substrate;
A back side electrode forming step of forming a back side electrode on the back side of the semiconductor substrate;
The manufacturing method of the solar cell characterized by including. - 前記半導体基板の面内における前記第２不純物拡散層の面積が前記受光面側電極の面積よりも小であり、
前記受光面側電極が、前記第２不純物拡散層の全ての領域を覆って設けられること、
を特徴とする請求項８に記載の太陽電池の製造方法。 An area of the second impurity diffusion layer in a plane of the semiconductor substrate is smaller than an area of the light receiving surface side electrode;
The light-receiving surface side electrode is provided to cover the entire region of the second impurity diffusion layer;
The method for producing a solar cell according to claim 8. - 前記第２不純物拡散層の表面が平坦とされること、
を特徴とする請求項８または９に記載の太陽電池の製造方法。 The surface of the second impurity diffusion layer is flat;
The method for producing a solar cell according to claim 8 or 9, wherein: - 前記第２不純物拡散層の表面が少なくとも部分的に凹凸形状とされること、
を特徴とする請求項８または９に記載の太陽電池の製造方法。 The surface of the second impurity diffusion layer is at least partially uneven,
The method for producing a solar cell according to claim 8 or 9, wherein: - 前記第２不純物拡散層がメッシュパターンで形成されること、
を特徴とする請求項１１に記載の太陽電池の製造方法。 The second impurity diffusion layer is formed in a mesh pattern;
The method for manufacturing a solar cell according to claim 11. - 前記受光面側電極が、細線形状を有するグリッド電極と、前記グリッド電極より太幅形状を有して前記グリッド電極に接続するバス電極とからなり、
前記バス電極に覆われる領域のみに前記第２不純物拡散層が形成されること、
を特徴とする請求項８～１２のいずれか１つに記載の太陽電池の製造方法。 The light-receiving surface side electrode is composed of a grid electrode having a thin line shape, and a bus electrode having a shape wider than the grid electrode and connected to the grid electrode,
The second impurity diffusion layer is formed only in a region covered with the bus electrode;
The method for producing a solar cell according to any one of claims 8 to 12, wherein: - 前記不純物拡散層形成工程では、
前記半導体基板の一面側の全面に前記第２不純物拡散層を形成する工程と、
前記第２不純物拡散層上に保護膜を形成する工程と、
前記保護膜に前記第１不純物拡散層のパターンで微小孔を形成する工程と、
前記微小孔を介して前記前記半導体基板の一面側をウエットエッチングすることにより前記第２不純物拡散層をパターニングするとともに前記半導体基板の一面側における前記第２不純物拡散層以外の領域に前記凹凸形状を形成する工程と、
前記半導体基板の一面側における前記凹凸形状が形成された領域に前記第１不純物拡散層を形成する工程と、
を含むことを特徴とする請求項８～１３のいずれか１つに記載の太陽電池の製造方法。 In the impurity diffusion layer forming step,
Forming the second impurity diffusion layer over the entire surface of one surface of the semiconductor substrate;
Forming a protective film on the second impurity diffusion layer;
Forming micropores in the protective film with the pattern of the first impurity diffusion layer;
The second impurity diffusion layer is patterned by wet-etching the one surface side of the semiconductor substrate through the micro holes, and the uneven shape is formed in a region other than the second impurity diffusion layer on the one surface side of the semiconductor substrate. Forming, and
Forming the first impurity diffusion layer in a region where the uneven shape is formed on one surface side of the semiconductor substrate;
The method for manufacturing a solar cell according to any one of claims 8 to 13, wherein - 前記第２不純物拡散層の輪郭を、前記第２不純物拡散層の延在方向において蛇行した形状に形成し、
前記第１不純物拡散層のうち、前記第２不純物拡散層の幅方向において前記第２不純物拡散層に隣接して部分的に前記第２不純物拡散層側に膨らんだ領域は、前記受光面側電極に当接させて前記受光面側電極で覆い、
前記第２不純物拡散層のうち、前記第２不純物拡散層の幅方向において前記第１不純物拡散層に隣接して部分的に前記第１不純物拡散層側に膨らんだ領域の端部近傍は、前記受光面側電極で覆わないこと、
を特徴とする請求項８～１４のいずれか１つに記載の太陽電池の製造方法。 Forming an outline of the second impurity diffusion layer in a meandering shape in the extending direction of the second impurity diffusion layer;
Of the first impurity diffusion layer, a region that swells partially toward the second impurity diffusion layer adjacent to the second impurity diffusion layer in the width direction of the second impurity diffusion layer is the light receiving surface side electrode. Covered with the light receiving surface side electrode,
Of the second impurity diffusion layer, in the width direction of the second impurity diffusion layer, adjacent to the first impurity diffusion layer, the vicinity of the end of the region partially bulging toward the first impurity diffusion layer is Do not cover with the light receiving surface side electrode,
The method for producing a solar cell according to any one of claims 8 to 14, wherein: - 請求項１～７のいずれか１つに記載の太陽電池の少なくとも２つ以上が電気的に直列または並列に接続されてなること、
を特徴とする太陽電池モジュール。 At least two or more of the solar cells according to any one of claims 1 to 7 are electrically connected in series or in parallel;
A solar cell module characterized by.
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| JP2014143272A (en) * | 2013-01-23 | 2014-08-07 | Mitsubishi Electric Corp | Method for roughening substrate surface and method for manufacturing photovoltaic device |
| JP2016111357A (en) * | 2014-12-09 | 2016-06-20 | 三菱電機株式会社 | Solar battery, solar battery module, and method of manufacturing solar battery |
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| JP2004193350A (en) * | 2002-12-11 | 2004-07-08 | Sharp Corp | Solar battery cell and its manufacturing method |
| JP2005123447A (en) * | 2003-10-17 | 2005-05-12 | Shin Etsu Handotai Co Ltd | Solar battery and method for manufacturing the same |
| JP2010056241A (en) * | 2008-08-27 | 2010-03-11 | Mitsubishi Electric Corp | Photovoltaic power device, and method for manufacturing the same |
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| US8697553B2 (en) * | 2008-06-11 | 2014-04-15 | Intevac, Inc | Solar cell fabrication with faceting and ion implantation |
| JP2009290235A (en) * | 2009-09-07 | 2009-12-10 | Mitsubishi Electric Corp | Solar cell, and manufacturing method thereof |
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| JP2005123447A (en) * | 2003-10-17 | 2005-05-12 | Shin Etsu Handotai Co Ltd | Solar battery and method for manufacturing the same |
| JP2010056241A (en) * | 2008-08-27 | 2010-03-11 | Mitsubishi Electric Corp | Photovoltaic power device, and method for manufacturing the same |
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| JP2014143272A (en) * | 2013-01-23 | 2014-08-07 | Mitsubishi Electric Corp | Method for roughening substrate surface and method for manufacturing photovoltaic device |
| JP2016111357A (en) * | 2014-12-09 | 2016-06-20 | 三菱電機株式会社 | Solar battery, solar battery module, and method of manufacturing solar battery |
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