JP2002270874A - Method for manufacturing transparent conductive film having irregular shape - Google Patents
Method for manufacturing transparent conductive film having irregular shapeInfo
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- JP2002270874A JP2002270874A JP2001070104A JP2001070104A JP2002270874A JP 2002270874 A JP2002270874 A JP 2002270874A JP 2001070104 A JP2001070104 A JP 2001070104A JP 2001070104 A JP2001070104 A JP 2001070104A JP 2002270874 A JP2002270874 A JP 2002270874A
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- Prior art keywords
- transparent conductive
- conductive film
- film
- ultraviolet
- light
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、光散乱効果のあ
る凹凸形状を有する透明導電膜に関し、特に、光起電力
装置の裏面金属膜と半導体層との間に設けられる透明導
電膜に用いて好適な凹凸形状を有する透明導電膜の製造
方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film having an uneven shape having a light scattering effect, and more particularly to a transparent conductive film provided between a back metal film and a semiconductor layer of a photovoltaic device. The present invention relates to a method for manufacturing a transparent conductive film having a suitable uneven shape.
【０００２】[0002]
【従来の技術】従来、原料ガスのグロー放電分解等によ
り形成される非晶質シリコン（以下、ａ−Ｓｉとい
う。）を主材料にした光起電力装置は、薄膜、大面積化
が容易という特長を持ち、低コスト光起電力装置として
期待されている。2. Description of the Related Art Conventionally, a photovoltaic device using amorphous silicon (hereinafter referred to as a-Si) as a main material formed by glow discharge decomposition of a source gas or the like is easy to make a thin film and a large area. It has features and is expected as a low-cost photovoltaic device.
【０００３】この種の光起電力装置としては、ｐｉｎ接
合を有するｐｉｎ型ａ−Ｓｉ光起電力が知られている。
図１１はこのような光起電力装置の構造を示し、ガラス
基板１上に、酸化錫（ＳｎＯ2）などの透明電極２、内
部にｐｉｎ接合を有する光活性層となる薄膜半導体層
３、透明導電膜４、裏面金属電極５を順次積層すること
により作成される。前記薄膜半導体層３は、ｐ型ａ−Ｓ
ｉＣ層３１、ｉ型ａ−Ｓｉ層３２、ｎ型微結晶シリコン
（以下、μｃ−Ｓｉという。）層３３を順次積層して構
成されている。この光起電力装置は、ガラス基板１を通
して入射する光により、光起電力が発生する。As this type of photovoltaic device, a pin type a-Si photovoltaic device having a pin junction is known.
FIG. 11 shows the structure of such a photovoltaic device. A transparent electrode 2 such as tin oxide (SnO 2 ) is formed on a glass substrate 1, a thin film semiconductor layer 3 serving as a photoactive layer having a pin junction inside, and a transparent substrate. It is formed by sequentially laminating the conductive film 4 and the back metal electrode 5. The thin film semiconductor layer 3 is made of p-type a-S
An iC layer 31, an i-type a-Si layer 32, and an n-type microcrystalline silicon (hereinafter referred to as μc-Si) layer 33 are sequentially laminated. This photovoltaic device generates photovoltaic power by light incident through the glass substrate 1.
【０００４】上記した半導体層３と裏面金属電極５との
間に設けられる透明導電膜４は、半導体層３と裏面金属
電極４との合金化等防ぐとともに、発電層であるｉ型ａ
−Ｓｉ層３２で吸収されなかった光を裏面金属電極５で
反射させて、再びｉ型ａ−Ｓｉ層３２に入射させる際に
光を散乱させるものである。The transparent conductive film 4 provided between the semiconductor layer 3 and the back metal electrode 5 prevents the semiconductor layer 3 and the back metal electrode 4 from being alloyed or the like, and also forms an i-type a
Light that is not absorbed by the -Si layer 32 is reflected by the back metal electrode 5 and scatters light when the light is again incident on the i-type a-Si layer 32.
【０００５】上記した透明導電膜（ＴＣＯ）の形成方法
としては、第１にＩＴＯ、ＺｎＯなどの透明導電膜をス
パッタで下地の凹凸形状に合わせてほぼフラットに形成
する方法がある。As a method for forming the above-mentioned transparent conductive film (TCO), first, there is a method in which a transparent conductive film such as ITO or ZnO is formed almost flat by sputtering so as to conform to the irregularities of the base.
【０００６】また、第２の方法として、透明導電膜とし
てＺｎＯを用いる場合には、ＺｎＯ膜を形成した後、希
塩酸エッチングを行うことで、５０００Å前後の表面凹
凸形状を形成することができる。As a second method, when ZnO is used as the transparent conductive film, a surface unevenness of about 5000 ° can be formed by dilute hydrochloric acid etching after forming the ZnO film.
【０００７】一方、高温形成（１０００℃以上）で形成
されたガラス基板上に５００℃程度の熱ＣＶＤプロセス
でＳｎＯ2膜を形成する。この時、条件によっては５０
００〜８０００Å程度の凹凸直径と深さを有する凹凸形
状を表面に形成することができる。On the other hand, a SnO 2 film is formed on a glass substrate formed at a high temperature (1000 ° C. or higher) by a thermal CVD process at about 500 ° C. At this time, 50
An uneven shape having an uneven diameter and a depth of about 00 to 8000 ° can be formed on the surface.
【０００８】[0008]
【発明が解決しようとする課題】上記した第１の方法で
は、下地の凹凸形状通りの形状になり、光散乱効果に適
した所望の凹凸の形成が行えないという難点がある。The first method described above has a drawback in that the shape of the underlayer becomes the same as that of the unevenness, and the desired unevenness suitable for the light scattering effect cannot be formed.
【０００９】また、第２の方法では、光起電力装置の電
極として適した高い結晶性を有するＺｎＯでは、凹凸幅
（直径）の制御はエッチング時間によって可能である
が、凹凸深さは制御不可能である。特に、裏面電極側に
用いる透明導電膜は、その膜厚が５００〜１０００Å程
度と薄く形成される。このため、高い結晶性を有するＺ
ｎＯ膜をエッチングにより凹凸化できてもエッチング前
の透明導電膜の膜厚が厚い場合は光の吸収ロスが大きく
なり電流は増加しない。また、エッチング前の透明導電
膜が薄い（約１０００Å程度）と透明導電膜が部分的に
エッチングされすぎて高抵抗になるという問題がある。In the second method, in the case of ZnO having high crystallinity suitable as an electrode of a photovoltaic device, the width (diameter) of the unevenness can be controlled by the etching time, but the depth of the unevenness cannot be controlled. It is possible. In particular, the transparent conductive film used on the back electrode side is formed as thin as about 500 to 1000 °. Therefore, Z having high crystallinity
Even if the nO film can be made uneven by etching, if the thickness of the transparent conductive film before etching is large, light absorption loss increases and the current does not increase. Further, when the transparent conductive film before etching is thin (about 1000 °), there is a problem that the transparent conductive film is partially etched excessively and becomes high in resistance.
【００１０】さらに、裏面電極側において、５００℃程
度の熱ＣＶＤプロセスを用いてＳｎＯ2膜の凹凸化をす
る場合は、下地の半導体形成温度より高温になるため太
陽電池の特性は熱ダメージにより大きく低下する。しか
も、下地がＳｉＯ2（ガラス材料）と異なるため、ガラ
ス基板上のような良好な凹凸形成が形成できないという
問題がある。Further, when the SnO 2 film is made uneven on the back electrode side using a thermal CVD process at about 500 ° C., the temperature of the SnO 2 film becomes higher than the temperature at which the underlying semiconductor is formed. descend. In addition, since the underlayer is different from SiO 2 (glass material), there is a problem that good unevenness cannot be formed as on a glass substrate.
【００１１】この発明は、上記した従来の問題点を解決
するためになされたものにして、光散乱効果のある凹凸
形状を有する透明導電膜を容易に製造することができる
方法を提供することを目的とする。The present invention has been made in order to solve the above-mentioned conventional problems, and provides a method for easily manufacturing a transparent conductive film having a concavo-convex shape having a light scattering effect. Aim.
【００１２】[0012]
【課題を解決するための手段】この発明は、透明導電膜
表面に選択的に紫外線を照射することにより、透明導電
膜と接触する酸性溶液における透明導電膜のエッチング
レートを紫外線の照射強度によって選択的に制御し、透
明導電膜表面に凹凸を形成することを特徴とする。SUMMARY OF THE INVENTION The present invention selectively irradiates the surface of a transparent conductive film with ultraviolet light, thereby selecting an etching rate of the transparent conductive film in an acidic solution in contact with the transparent conductive film according to the irradiation intensity of the ultraviolet light. Characterized by forming irregularities on the surface of the transparent conductive film.
【００１３】前記選択的に紫外線を照射する手段とし
て、回折格子に紫外線レーザを照射して光干渉させれば
よい。As means for selectively irradiating ultraviolet rays, an ultraviolet laser may be applied to the diffraction grating to cause light interference.
【００１４】この発明は、薄膜半導体層形成後その上に
フラットな透明導電膜（ＩＴＯ、ＳｎＯ2、ＺｎＯ等）
をスパッタ法（２００〜３５０℃程度）で形成し、形成
した裏面透明導電膜表面を希塩酸または希酢酸に浸すと
ともに、その表面に紫外線を選択的に照射する。この
時、回折格子に紫外線レーザを照射して光干渉させる
と、幅５００〜８００Å内で（１）紫外線受光されず希
塩酸（希酢酸）と接触する透明導電膜部のエッチング速
度と、（２）紫外線受光と希塩酸（希酢酸）接触が同時
におこる透明導電膜部のエッチング速度が少なくとも１
０倍以上変化させることができる。エッチング速度が最
も遅い部分から最も速い部分にかけて紫外線の照射強度
とエッチング速度を連続的に増加変化させる。According to the present invention, after a thin film semiconductor layer is formed, a flat transparent conductive film (ITO, SnO 2 , ZnO, etc.) is formed thereon.
Is formed by a sputtering method (about 200 to 350 ° C.), the surface of the formed rear transparent conductive film is immersed in dilute hydrochloric acid or dilute acetic acid, and the surface is selectively irradiated with ultraviolet rays. At this time, when the diffraction grating is irradiated with an ultraviolet laser to cause light interference, within the width of 500 to 800 °, (1) the etching rate of the transparent conductive film portion which is not received with ultraviolet light and comes into contact with dilute hydrochloric acid (dilute acetic acid); The etching rate of the transparent conductive film portion where ultraviolet light reception and dilute hydrochloric acid (dilute acetic acid) contact occur simultaneously is at least 1
It can be changed by 0 times or more. The irradiation intensity of ultraviolet rays and the etching rate are continuously increased and changed from the portion having the slowest etching speed to the portion having the fastest etching speed.
【００１５】上記のように、紫外線レーザ光線の干渉を
利用し、位相の異なる２つのレーザ光線を重ねることで
紫外線の強度分布をつくる。紫外線の強度が高い部分が
凹部になり、強度の低い（ほとんど当たらない部分）が
凸部になる。As described above, the intensity distribution of ultraviolet rays is created by superposing two laser beams having different phases on the basis of the interference of ultraviolet laser beams. The portion where the intensity of the ultraviolet light is high becomes the concave portion, and the portion where the intensity is low (the portion which hardly hits) becomes the convex portion.
【００１６】幅、深さともに５００〜８００Å程度の凹
凸形状を形成でき、光閉じ込め効果の高い凹凸形状を裏
面電極に形成でき、太陽電池のＩｓｃ効率が上昇させる
ことができる。[0016] An uneven shape having a width and depth of about 500 to 800 ° can be formed, an uneven shape having a high light confinement effect can be formed on the back electrode, and the Isc efficiency of the solar cell can be increased.
【００１７】前記透明導電膜として酸化亜鉛を用い、エ
ッチング溶液として、濃度が０．０２％以下の塩酸を用
いると、エッチング速度が少なくとも１０倍以上変化さ
せることができる。When zinc oxide is used as the transparent conductive film and hydrochloric acid having a concentration of 0.02% or less is used as an etching solution, the etching rate can be changed at least ten times or more.
【００１８】前記透明導電膜として酸化亜鉛を用い、エ
ッチング溶液として、濃度が０．１％以下の酢酸を用い
ると、エッチング速度が少なくとも１０倍以上変化させ
ることができる。If zinc oxide is used as the transparent conductive film and acetic acid having a concentration of 0.1% or less is used as the etching solution, the etching rate can be changed at least ten times or more.
【００１９】[0019]
【発明の実施の形態】以下、この発明の実施形態につき
図面を参照して説明する。この発明の各実施形態は、上
記した従来の光起電力装置の半導体層３と裏面金属膜４
との間に設けられる裏面側の透明導電膜４に適用される
ものである。この実施形態を図１に示す。なお、図１１
と同一構成の部分には同一符号を付す。Embodiments of the present invention will be described below with reference to the drawings. Each embodiment of the present invention relates to the semiconductor layer 3 and the back metal film 4 of the above-described conventional photovoltaic device.
This is applied to the transparent conductive film 4 on the back surface provided between them. This embodiment is shown in FIG. Note that FIG.
The same reference numerals are given to parts having the same configuration as that of FIG.
【００２０】（実施形態１）この実施形態１は、図１に
示す光起電力装置の裏面側透明導電膜４として、酸化亜
鉛（ＺｎＯ）を用いたものである。また、表面側のガラ
ス基板１上に設けられる透明導電膜２もＺｎＯ膜を用い
た。Embodiment 1 In Embodiment 1, zinc oxide (ZnO) is used as the transparent conductive film 4 on the back surface of the photovoltaic device shown in FIG. The transparent conductive film 2 provided on the glass substrate 1 on the front side also used a ZnO film.
【００２１】この実施形態におけるガラス基板１のサイ
ズは１０ｃｍ×１０ｃｍ、厚み５ｍｍで、透明導電膜２
としては厚さ３０００〜１２０００ÅのＺｎＯ膜を用い
た。このＺｎＯ膜は公知のＤＣマグネトロンスパッタ法
により、基板温度：１００〜３００℃。Ａｒ：４００ｓ
ｃｃｍとＯ2：１０ｓｃｃｍを混合した１Ｐａ雰囲気下
で、大きさ３００ｃｍ2の３％Ａｌ2Ｏ3ドープＺｎＯタ
ーゲットに０．１ｋＷの電力を印加して形成した。Ｚｎ
Ｏ膜の表面は、希塩酸エッチングを施すことにより、凹
凸形状が形成されている。The size of the glass substrate 1 in this embodiment is 10 cm × 10 cm, the thickness is 5 mm, and the transparent conductive film 2
Was used as a ZnO film having a thickness of 3000 to 12000 °. The substrate temperature of this ZnO film is 100 to 300 ° C. by a known DC magnetron sputtering method. Ar: 400s
It was formed by applying a power of 0.1 kW to a 3% Al 2 O 3 -doped ZnO target having a size of 300 cm 2 under a 1 Pa atmosphere in which ccm and O 2 were mixed at 10 sccm. Zn
The surface of the O film is formed with an uneven shape by dilute hydrochloric acid etching.
【００２２】これらの透明導電膜２を設けたガラス基板
１上に第１表に示す条件により、公知の平行平板のプラ
ズマＣＶＤ装置を用いて、ｐ層３１、ｉ層３２、ｎ層３
３からなる薄膜半導体層３の形成を行った。ここで、放
電電極面積は１５００ｃｍ2、電極間隔は４０ｍｍであ
る。Under the conditions shown in Table 1, a p-layer 31, an i-layer 32, and an n-layer 3 were formed on a glass substrate 1 provided with the transparent conductive film 2 under the conditions shown in Table 1 using a known parallel-plate plasma CVD apparatus.
3 was formed. Here, the discharge electrode area is 1500 cm 2 , and the electrode interval is 40 mm.
【００２３】[0023]
【表１】 [Table 1]
【００２４】さらに、上記非晶質半導体層３に裏面側透
明電極として厚み６０００ÅのＺｎＯ膜を基板温度２０
０℃のＤＣマグネトロンスパッタ法により、Ａｒ：４０
０ｓｃｃｍの１Ｐａ雰囲気下で、大きさ３００ｃｍ2の
ＺｎＯターゲットに０．１ｋＷの電力を印加して作製し
た。Further, a 6000.degree.-thick ZnO film is formed on the amorphous semiconductor layer 3 as a back surface side transparent electrode at a substrate temperature of 20.degree.
Ar: 40 by DC magnetron sputtering at 0 ° C.
It was fabricated by applying a power of 0.1 kW to a ZnO target having a size of 300 cm 2 under a 1 Pa atmosphere of 0 sccm.
【００２５】この発明の特徴とするところは、上記のよ
うに形成した裏面側透明電極膜の表面をエッチングして
表面に光散乱効果を有する凹凸形状を形成すると共に、
その膜厚も薄くするものである。このため、形成した裏
面側の透明電極膜表面を希塩酸などの酸性溶液に浸すと
ともに、その表面に紫外線を選択的に照射する。このと
き、微細な幅でエッチング速度を変化させるために紫外
線レーザ光線の干渉を利用し、位相の異なる２つのレー
ザ光線を重ねることで紫外線の強度分布をつくる。これ
は、紫外線の強度が高い部分は、エッチング速度が速
く、紫外線の強度が低い（ほとんど当たらない部分）は
エッチング速度が極めて遅くなることを利用したもので
ある。The present invention is characterized in that the surface of the transparent electrode film formed on the back side formed as described above is etched to form an uneven shape having a light scattering effect on the surface.
Its thickness is also reduced. Therefore, the surface of the formed transparent electrode film on the back side is immersed in an acidic solution such as dilute hydrochloric acid, and the surface is selectively irradiated with ultraviolet rays. At this time, in order to change the etching rate in a minute width, the interference of the ultraviolet laser beam is used, and the intensity distribution of the ultraviolet ray is created by superimposing two laser beams having different phases. This is based on the fact that the etching rate is high in a portion where the intensity of the ultraviolet light is high, and extremely low when the intensity of the ultraviolet light is low (a portion where the ultraviolet light is hardly applied).
【００２６】即ち、（１）紫外線受光されず希塩酸（ま
たは希酢酸）と接触する透明導電膜部のエッチング速度
と、（２）紫外線受光と希塩酸（希または酢酸）接触が
同時におこる透明導電膜部のエッチング速度が、エッチ
ング液の濃度を選択することで、少なくとも１０倍以上
変化させることができる。That is, (1) the etching rate of the transparent conductive film portion which does not receive ultraviolet light and comes into contact with dilute hydrochloric acid (or dilute acetic acid); and (2) the transparent conductive film portion where ultraviolet light reception and dilute hydrochloric acid (dilute or acetic acid) occur simultaneously. Can be changed at least ten times or more by selecting the concentration of the etching solution.
【００２７】紫外線を照射された部分と照射されていな
い部分とのエッチング速度の比を調べた結果を表２及び
表３に示す。表２は、塩酸の場合、表３は酢酸の場合を
示す。Tables 2 and 3 show the results of examining the ratio of the etching rate between the part irradiated with ultraviolet rays and the part not irradiated with ultraviolet rays. Table 2 shows the case of hydrochloric acid, and Table 3 shows the case of acetic acid.
【００２８】[0028]
【表２】 [Table 2]
【００２９】[0029]
【表３】 [Table 3]
【００３０】表２より、塩酸の場合には、濃度が０．０
２％以下になるとエッチング速度の比が１０倍以上とな
り、表３より、酢酸の場合には、濃度が０．１％以下に
なるとエッチング速度の比が１０倍以上となる。According to Table 2, in the case of hydrochloric acid, the concentration was 0.0
When it is 2% or less, the etching rate ratio becomes 10 times or more. From Table 3, in the case of acetic acid, when the concentration becomes 0.1% or less, the etching rate ratio becomes 10 times or more.
【００３１】このように、紫外線レーザ光線の干渉を利
用し、位相の異なる２つのレーザ光線を重ねることで紫
外線の強度分布をつくる。紫外線の強度が高い部分が凹
部になり、強度の低い（ほとんど当たらない部分）が凸
部にすることができる。As described above, by utilizing the interference of the ultraviolet laser beam, the intensity distribution of the ultraviolet ray is created by superimposing two laser beams having different phases. A portion where the intensity of the ultraviolet light is high can be a concave portion, and a portion where the intensity is low (a portion hardly hit) can be a convex portion.
【００３２】この実施形態においては、エッチング条件
として、エッチング液は濃度０．０１％の塩酸溶液を使
用した。紫外線は透明導電膜表面の照射箇所で最大２０
ｍＷ／ｃｍ2とした。紫外線レーザとして、波長１９３
ｎｍのエキシマレーザを用いた。In this embodiment, as an etching condition, a hydrochloric acid solution having a concentration of 0.01% was used as an etching solution. UV rays are maximum 20 at the irradiation spot on the surface of the transparent conductive film.
mW / cm 2 . As an ultraviolet laser, a wavelength of 193 is used.
nm excimer laser was used.
【００３３】紫外線の干渉パターンは２光路分離された
レーザ光の干渉を利用して光の強弱をつけ透明導電膜表
面に照射する。この干渉パターンを設ける方法につき説
明する。The ultraviolet interference pattern irradiates the surface of the transparent conductive film with the intensity of the light by utilizing the interference of the laser light separated by two optical paths. A method for providing this interference pattern will be described.
【００３４】図２に示すように、回折格子２０を介して
透明導電膜１０上に紫外線レーザを照射すると、紫外線
が干渉する。ここで、紫外線の波長をλ（ｃｍ）、回折
格子と照射する透明導電膜との距離をＬ（ｃｍ）、格子
の間隔をｄ（ｃｍ）、回折格子による明線の間隔をΔＸ
（ｃｍ）とすると、それぞれの関係は次のようになる。As shown in FIG. 2, when the transparent conductive film 10 is irradiated with an ultraviolet laser through the diffraction grating 20, the ultraviolet light interferes. Here, the wavelength of the ultraviolet light is λ (cm), the distance between the diffraction grating and the transparent conductive film to be irradiated is L (cm), the interval between the gratings is d (cm), and the interval between the bright lines by the diffraction grating is ΔX.
(Cm), the respective relationships are as follows.
【００３５】ΔＸ＝Ｌ・λ／ｄΔX = L · λ / d
【００３６】この実施形態では、紫外線レーザとして、
波長λ：１９３ｎｍのエキシマレーザを用い、距離Ｌを
１ｃｍ、格子の間隔ｄを３．８６ｃｍとした。その結
果、ΔＸは５０ｎｍ（５００Å）となる。In this embodiment, as the ultraviolet laser,
Using an excimer laser having a wavelength λ of 193 nm, the distance L was set to 1 cm, and the interval d between the gratings was set to 3.86 cm. As a result, ΔX becomes 50 nm (500 °).
【００３７】上記した回折格子２０を用いることによ
り、紫外線レーザ光が干渉して光の強弱がつく理由をさ
らに、図３及び図４を参照して説明する。With reference to FIGS. 3 and 4, the reason why the use of the diffraction grating 20 causes the ultraviolet laser light to interfere with each other to increase or decrease the intensity of the light will be described.
【００３８】図３は同位相の紫外線の強度分布を示す説
明図であり、回折格子を経て、同位相のレーザ光が同図
（ａ）に示すように、透明導電膜上に照射される。透明
導電膜上では同図（ｂ）に示すように、２つのレーザ光
が重畳され、同図（ｃ）に示すように、強度の強いレー
ザ光として、透明導電膜上に照射される。FIG. 3 is an explanatory diagram showing the intensity distribution of ultraviolet light having the same phase, and the laser light having the same phase is irradiated on the transparent conductive film through the diffraction grating as shown in FIG. On the transparent conductive film, two laser beams are superimposed as shown in FIG. 4B, and as shown in FIG. 4C, the laser beam is irradiated on the transparent conductive film as a laser beam having high intensity.
【００３９】図４は反転位相の紫外線の強度分布を示す
説明図であり、回折格子を経て、同位相のレーザ光が同
図（ａ）に示すように、透明導電膜上に照射される。透
明導電膜上では同図（ｂ）に示すように、２つのレーザ
光が重畳され、同図（ｃ）に示すように、２つのレーザ
光はうち消し合い、透明導電膜上には、レーザ光は照射
されなくなる。FIG. 4 is an explanatory view showing the intensity distribution of the ultraviolet light having the inverted phase. The laser light having the same phase is irradiated on the transparent conductive film through the diffraction grating as shown in FIG. On the transparent conductive film, two laser beams are superimposed as shown in FIG. 3B, and as shown in FIG. No light is emitted.
【００４０】図５は紫外線の干渉縞の概略図であり、上
から見た状態を示している。図５（ａ）に示すように、
回折格子により、レーザ光に干渉縞が形成され、図３及
び図４に示すように、同位相の紫外線が明線となり、反
転位相の紫外線は透明電導膜上に光は照射されない。そ
の結果、図５（ｂ）に示すように、ΔＸのスパンで、明
線が現れ、その部分に紫外線が照射されることになる。FIG. 5 is a schematic view of the interference fringes of the ultraviolet rays, which is viewed from above. As shown in FIG.
Interference fringes are formed in the laser beam by the diffraction grating, and as shown in FIGS. 3 and 4, ultraviolet rays having the same phase become bright lines, and ultraviolet rays having the inverted phase do not irradiate the transparent conductive film with light. As a result, as shown in FIG. 5B, a bright line appears in a span of ΔX, and the portion is irradiated with ultraviolet rays.
【００４１】このように、上記の回折格子２０を用いて
紫外線レーザ光を照射すると、図６に示すように、５０
０Åの間隔で、エッチング速度の速い箇所が形成される
ことになる。As described above, when the ultraviolet laser beam is irradiated using the diffraction grating 20, as shown in FIG.
At an interval of 0 °, a portion having a high etching rate is formed.
【００４２】この状態で、上記したエッチングの速度比
が１０倍以上になる濃度の酸性溶液中に透明導電膜４を
形成した基板を浸し、エッチングを施すと、図７に示す
ように、光散乱効果に優れた凹凸を形成することができ
る。このように形成された透明導電膜４ａは、その膜厚
も薄くできる。In this state, when the substrate on which the transparent conductive film 4 is formed is immersed in an acidic solution having a concentration at which the above-mentioned etching rate ratio becomes 10 times or more, and the substrate is etched, light scattering occurs as shown in FIG. Irregularities excellent in effect can be formed. The thickness of the transparent conductive film 4a thus formed can be reduced.
【００４３】次に、透明導電膜４の全面に凹凸を形成す
る方法につき図８ないし図１０に従い説明する。Next, a method for forming irregularities on the entire surface of the transparent conductive film 4 will be described with reference to FIGS.
【００４４】図８（ａ）に示すように、３．８６ｃｍの
間隔で回折格子を設け、この回折格子は開閉式に構成し
ている。そして、図８（ｂ）に示すように、回折格子を
数字の順番に従って開口させる。また、回折格子を開閉
式にする代わりに、図９に示すように、透明導電膜を設
けた基板１０の前方をマスク２１で覆い所定の回折格子
からのレーザ光が照射されるように構成してもよい。As shown in FIG. 8A, diffraction gratings are provided at an interval of 3.86 cm, and the diffraction grating is configured to be openable and closable. Then, as shown in FIG. 8B, the diffraction grating is opened according to the numerical order. Further, instead of making the diffraction grating openable, as shown in FIG. 9, the front of the substrate 10 provided with the transparent conductive film is covered with a mask 21 so that laser light from a predetermined diffraction grating is irradiated. You may.
【００４５】このように、順次回折格子から照射される
領域を変化させることで、図１０に示すように、透明導
電膜を形成した基板１０の全面に選択的に紫外線が照射
されることになる。この実施形態では、５００Åの間隔
でレーザ強度の照射が高い領域が形成されることにな
る。このように、紫外線レーザを選択的に照射して、酸
性溶液中にしたしエッチングすることで、透明導電膜４
ａの表面には所望の凹凸が形成される。As described above, by sequentially changing the area irradiated from the diffraction grating, as shown in FIG. 10, the entire surface of the substrate 10 on which the transparent conductive film is formed is selectively irradiated with ultraviolet rays. . In this embodiment, regions with high laser intensity irradiation are formed at intervals of 500 °. In this manner, the transparent conductive film 4 is selectively irradiated with an ultraviolet laser, soaked in an acidic solution and etched.
Desired irregularities are formed on the surface of a.
【００４６】その後、図１に示すように、スパッタ法に
よりＡｇからなる裏面金属５を透明導電膜４ａ上に形成
する。この実施形態では、厚み２０００ÅのＡｇを基板
温度２００℃のＤＣマグネトロンスパッタ法により、Ａ
ｒ：４００ｓｃｃｍの１Ｐａ雰囲気下で、大きさ３００
ｃｍ2のＡｇターゲットに０．１ｋＷの電力を印加して
作製した。Thereafter, as shown in FIG. 1, a back metal 5 made of Ag is formed on the transparent conductive film 4a by a sputtering method. In this embodiment, Ag having a thickness of 2000 mm is deposited on the substrate by DC magnetron sputtering at a substrate temperature of 200 ° C.
r: 300 sccm under a 1 Pa atmosphere and a size of 300
It was fabricated by applying a power of 0.1 kW to an Ag target of cm 2 .
【００４７】上記のようにして形成された透明導電膜４
ａを用いると、光散乱効果に優れ、太陽電池の電流及び
変換効率が向上する。参考までに、図１２に、上記した
従来の第１の方法で作成した透明導電膜を用いた光起電
力装置の断面図を、図１３に、従来の第２の方法で作成
した透明導電膜を用いた光起電力装置の断面図を示す。
図１２に示す構造では、透明導電膜４ｂはほぼフラット
に形成され、光の散乱効果が得られない、また、図１３
に示す構造では、透明導電膜４ｃの膜厚が厚くなり、光
の吸収ロスが多くなる。The transparent conductive film 4 formed as described above
When a is used, the light scattering effect is excellent, and the current and conversion efficiency of the solar cell are improved. For reference, FIG. 12 is a cross-sectional view of a photovoltaic device using the transparent conductive film formed by the above-described first conventional method, and FIG. 13 is a transparent conductive film formed by the second conventional method. 1 shows a cross-sectional view of a photovoltaic device using the same.
In the structure shown in FIG. 12, the transparent conductive film 4b is formed almost flat, and no light scattering effect can be obtained.
In the structure shown in (1), the thickness of the transparent conductive film 4c is increased, and the light absorption loss is increased.
【００４８】これに対して、図１に示すこの発明の透明
導電膜４ａを用いたものでは、膜厚も必要以上厚するこ
となく、光散乱効果に適した凹凸が得られる。On the other hand, in the case of using the transparent conductive film 4a of the present invention shown in FIG. 1, unevenness suitable for the light scattering effect can be obtained without increasing the film thickness more than necessary.
【００４９】（実施形態２：ＩＴＯ）次に、この発明の
実施形態２につき説明する。この実施形態２は、透明導
電膜４ａとして、ＩＴＯ膜を半導体層３上に形成し、実
施形態１と同様に、回折格子を用いてレーザを照射し、
エッチングした。エッチング液は濃度０．０５％の酢酸
溶液を使用した。その他は上記した実施形態１と同じ方
法で形成した。(Embodiment 2: ITO) Next, Embodiment 2 of the present invention will be described. In the second embodiment, an ITO film is formed on the semiconductor layer 3 as the transparent conductive film 4a, and laser irradiation is performed using a diffraction grating as in the first embodiment.
Etched. As an etching solution, an acetic acid solution having a concentration of 0.05% was used. Others were formed by the same method as the first embodiment.
【００５０】（実施形態３：ＳｎＯ2）次に、この発明
の実施形態３につき説明する。この実施形態３は、透明
導電膜４ａとして、ＳｎＯ2膜を半導体層３上に形成
し、実施形態１と同様に、回折格子を用いてレーザを照
射し、エッチングした。エッチング液は濃度０．０５％
の塩酸溶液に亜鉛粉末を溶解したもので、塩酸と亜鉛の
モル比は１：１のものを使用した。その他は上記した実
施形態１と同じ方法で形成した。(Embodiment 3: SnO 2 ) Next, Embodiment 3 of the present invention will be described. In the third embodiment, a SnO 2 film was formed on the semiconductor layer 3 as the transparent conductive film 4a, and laser irradiation and etching were performed using a diffraction grating as in the first embodiment. Etching solution concentration 0.05%
A solution prepared by dissolving zinc powder in a hydrochloric acid solution having a molar ratio of hydrochloric acid to zinc of 1: 1 was used. Others were formed by the same method as the first embodiment.
【００５１】次に、上記した実施形態１ないし３に基づ
いて、形成した光起電力装置の特性を測定した結果を表
４に示す。透明導電膜の出発膜厚は、ＳｎＯ2：１００
０Å、ＩＴＯ：１０００Å、ＺｎＯ：８００Åとした、
各特性は、エッチングを施していないそれぞれの光起電
力装置で規格化した。Next, Table 4 shows the results obtained by measuring the characteristics of the photovoltaic device formed based on Embodiments 1 to 3 described above. The starting film thickness of the transparent conductive film is SnO 2 : 100
0 °, ITO: 1000 °, ZnO: 800 °,
Each characteristic was standardized for each photovoltaic device that was not subjected to etching.
【００５２】[0052]
【表４】 [Table 4]
【００５３】表４から、この発明による透明導電膜を用
いることで、裏面電極での反射率が増加して、太陽電池
の電流、変換効率が上昇することが分かる。From Table 4, it can be seen that the use of the transparent conductive film according to the present invention increases the reflectance at the back electrode, and increases the current and conversion efficiency of the solar cell.
【００５４】[0054]
【発明の効果】以上説明したように、この発明によれ
ば、光散乱効果に優れた凹凸を有する透明導電膜を形成
することができる。従って、この透明導電膜を用いるこ
とで、裏面電極での反射率が増加して、太陽電池の電
流、変換効率が上昇させることができる。As described above, according to the present invention, it is possible to form a transparent conductive film having unevenness excellent in light scattering effect. Therefore, by using this transparent conductive film, the reflectance at the back electrode is increased, and the current and conversion efficiency of the solar cell can be increased.
【図１】この発明の透明導電膜を用いたｐｉｎ型ａ−Ｓ
ｉ光起電力装置の構造を示す断面図である。FIG. 1 shows a pin type aS using a transparent conductive film of the present invention.
It is sectional drawing which shows the structure of i photovoltaic device.
【図２】回折格子を介して紫外線レーザを照射する状態
を示す模式図である。FIG. 2 is a schematic diagram showing a state in which an ultraviolet laser is irradiated through a diffraction grating.
【図３】同位相の紫外線の強度分布を示す説明図であ
る。FIG. 3 is an explanatory diagram showing the intensity distribution of ultraviolet light having the same phase.
【図４】同位相の紫外線の強度分布を示す説明図であ
る。FIG. 4 is an explanatory diagram showing the intensity distribution of ultraviolet light having the same phase.
【図５】（ａ）は、紫外線の干渉縞の概略図、（ｂ）
は、干渉による明線の状態を示す概略図である。5A is a schematic diagram of interference fringes of ultraviolet rays, and FIG.
FIG. 3 is a schematic diagram showing a state of a bright line due to interference.
【図６】紫外線照射された領域とエッチングの速さの関
係を示す説明図である。FIG. 6 is an explanatory diagram showing a relationship between a region irradiated with ultraviolet rays and an etching speed.
【図７】この発明の透明導電膜のエッチングにより形成
される凹凸の関係を示す断面図である。FIG. 7 is a cross-sectional view showing a relationship between irregularities formed by etching the transparent conductive film of the present invention.
【図８】透明導電膜の全面に紫外線を選択的に照射させ
る一例を示す図である。FIG. 8 is a diagram showing an example of selectively irradiating the entire surface of a transparent conductive film with ultraviolet rays.
【図９】透明導電膜の全面に紫外線を選択的に照射させ
る一例を示す図である。FIG. 9 is a diagram showing an example of selectively irradiating the entire surface of a transparent conductive film with ultraviolet rays.
【図１０】透明導電膜の全面に紫外線を選択的に照射さ
せる状態の説明図である。FIG. 10 is an explanatory diagram of a state in which ultraviolet light is selectively irradiated on the entire surface of a transparent conductive film.
【図１１】ｐｉｎ接合を有するｐｉｎ型ａ−Ｓｉ光起電
力装置の構造を示す断面図である。FIG. 11 is a sectional view showing a structure of a pin type a-Si photovoltaic device having a pin junction.
【図１２】従来の第１の方法で作成した透明導電膜を用
いた光起電力装置の断面図である。FIG. 12 is a cross-sectional view of a photovoltaic device using a transparent conductive film formed by a conventional first method.
【図１３】従来の第２の方法で作成した透明導電膜を用
いた光起電力装置の断面図である。FIG. 13 is a sectional view of a photovoltaic device using a transparent conductive film formed by a second conventional method.
１ ガラス基板 ２ 透明電極 ３ 薄膜半導体層 ４、４ａ 透明導電膜 ５ 裏面金属電極 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Transparent electrode 3 Thin film semiconductor layer 4, 4a Transparent conductive film 5 Backside metal electrode
フロントページの続き Ｆターム(参考） 5F051 AA05 CB15 CB21 CB27 CB30 FA02 FA03 FA04 FA06 FA15 FA18 FA19 5G323 BA02 BB05 HA03 Continued on the front page F term (reference) 5F051 AA05 CB15 CB21 CB27 CB30 FA02 FA03 FA04 FA06 FA15 FA18 FA19 5G323 BA02 BB05 HA03
Claims (4)
することにより、透明導電膜と接触する酸性溶液におけ
る透明導電膜のエッチングレートを紫外線の照射強度に
よって選択的に制御し、透明導電膜表面に凹凸を形成す
ることを特徴とする凹凸形状を有する透明導電膜の製造
方法。1. A method for selectively irradiating a surface of a transparent conductive film with ultraviolet light, whereby an etching rate of the transparent conductive film in an acidic solution in contact with the transparent conductive film is selectively controlled by an irradiation intensity of the ultraviolet light. A method for manufacturing a transparent conductive film having an uneven shape, characterized by forming unevenness on a surface.
回折格子に紫外線レーザを照射して光干渉させることに
より行うものであることを特徴とする請求項１に記載の
凹凸形状を有する透明導電膜の製造方法。2. The means for selectively irradiating ultraviolet rays,
The method for producing a transparent conductive film having an uneven shape according to claim 1, wherein the method is performed by irradiating the diffraction grating with an ultraviolet laser to cause light interference.
エッチング溶液として、濃度が０．０２％以下の塩酸を
用いることを特徴とする請求項１または２に記載の凹凸
形状を有する透明導電膜の製造方法。3. A method using zinc oxide as the transparent conductive film,
3. The method according to claim 1, wherein hydrochloric acid having a concentration of 0.02% or less is used as the etching solution.
エッチング溶液として、濃度が０．１％以下の酢酸を用
いることを特徴とする請求項１または２に記載の凹凸形
状を有する透明導電膜の製造方法。4. A method using zinc oxide as the transparent conductive film,
3. The method according to claim 1, wherein acetic acid having a concentration of 0.1% or less is used as the etching solution.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010251704A (en) * | 2009-04-17 | 2010-11-04 | Lg Display Co Ltd | Method of manufacturing solar cell |
| KR20110064282A (en) * | 2009-12-07 | 2011-06-15 | 엘지디스플레이 주식회사 | Thin film solar cell and method for fabricaitng the same |
| JP2015222815A (en) * | 2009-05-14 | 2015-12-10 | ユニヴェルシテ ドゥ テクノロジー ドゥ トロワイＵｎｉｖｅｒｓｉｔｅ Ｄｅ Ｔｅｃｈｎｏｌｏｇｉｅ Ｄｅ Ｔｒｏｙｅｓ | Method of making film or wafer composed of material of metal oxide type or semiconductor type to have nanostructure |
| JP2019009402A (en) * | 2017-06-28 | 2019-01-17 | 国立研究開発法人物質・材料研究機構 | Solar cell and manufacturing method of the same |
-
2001
- 2001-03-13 JP JP2001070104A patent/JP4183394B2/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010251704A (en) * | 2009-04-17 | 2010-11-04 | Lg Display Co Ltd | Method of manufacturing solar cell |
| JP2015222815A (en) * | 2009-05-14 | 2015-12-10 | ユニヴェルシテ ドゥ テクノロジー ドゥ トロワイＵｎｉｖｅｒｓｉｔｅ Ｄｅ Ｔｅｃｈｎｏｌｏｇｉｅ Ｄｅ Ｔｒｏｙｅｓ | Method of making film or wafer composed of material of metal oxide type or semiconductor type to have nanostructure |
| KR20110064282A (en) * | 2009-12-07 | 2011-06-15 | 엘지디스플레이 주식회사 | Thin film solar cell and method for fabricaitng the same |
| KR101640815B1 (en) * | 2009-12-07 | 2016-07-19 | 엘지디스플레이 주식회사 | Thin film solar cell and method for fabricaitng the same |
| JP2019009402A (en) * | 2017-06-28 | 2019-01-17 | 国立研究開発法人物質・材料研究機構 | Solar cell and manufacturing method of the same |
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| Publication number | Publication date |
|---|---|
| JP4183394B2 (en) | 2008-11-19 |
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