JP2728874B2 - Semiconductor device manufacturing method - Google Patents

Semiconductor device manufacturing method

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Publication number
JP2728874B2
JP2728874B2 JP62168204A JP16820487A JP2728874B2 JP 2728874 B2 JP2728874 B2 JP 2728874B2 JP 62168204 A JP62168204 A JP 62168204A JP 16820487 A JP16820487 A JP 16820487A JP 2728874 B2 JP2728874 B2 JP 2728874B2
Authority
JP
Japan
Prior art keywords
thin film
semiconductor thin
substrate
film
group iii
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP62168204A
Other languages
Japanese (ja)
Other versions
JPS6411322A (en
Inventor
孝司 五十嵐
信弘 福田
賢司 宮地
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsui Chemicals Inc
Original Assignee
Mitsui Chemicals Inc
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Filing date
Publication date
Application filed by Mitsui Chemicals Inc filed Critical Mitsui Chemicals Inc
Priority to JP62168204A priority Critical patent/JP2728874B2/en
Publication of JPS6411322A publication Critical patent/JPS6411322A/en
Application granted granted Critical
Publication of JP2728874B2 publication Critical patent/JP2728874B2/en
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Classifications

    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy

Description

【発明の詳細な説明】 [技術分野] 本発明は半導体装置の製法に関し、特に透明導電膜付
透光性基板と半導体薄膜間の界面特性向上に優れた半導
体薄膜の低温形成方法に関する。 [背景技術] 半導体装置には結晶質や非晶質の半導体薄膜が利用さ
れている。これらは、通常、基板上に形成されるが、こ
のような基板としては、洗浄および/またはエッチング
により表面を清浄にした透明導電膜付基板が、半導体装
置に必要な電極を備えた材料として用いられることが多
い。例えば、非晶質の太陽電池においては入射光側の電
極として透明導電膜が用いられる。 しかしながら、モノシランやジシラン等のシラン系ガ
ス(SimH2m+2(m=1〜3)を主体として用いる従来の
グロー放電による形成法では、該透明導電膜が、半導体
薄膜を形成する際のグロー放電により損傷を受け、透明
性が低下したり、電気抵抗が増加したりした。これは、
得られる半導体装置の電気的な性質に悪い影響を及ぼす
要因となることを意味する。例えば、非晶質太陽電池に
おいては、その光電変換特性が著しく低下するという大
きな問題点があった。 かかる問題点を解決するために、従来、基板と半導体
薄膜との界面において、透明導電膜表面の損傷を避けつ
つ、電気的な特性の優れた半導体薄膜を形成する技術が
強く要求されていた。 本発明者は、かかる観点に基づき、フルオロシランを
主体とする原料ガスの放電分解について検討を進めた結
果、主原料としてフルオロシランを用いて、アモルファ
スシリコンの初期膜を形成することにより、透明電導膜
の電気抵抗の低下や透明性の低下をなんらひきおこすこ
となく半導体装置を形成できること、および、該反応ガ
ス中にIII族化合物を共存させることにより、p型ドー
ピングが可能であることを見出した。本発明は、本発明
者らによってはじめて見出された、かかる新規かつ重要
な知見に基づきなされるに至ったものである。 [発明の開示] 本発明は、透光性基板上に透明導電膜と半導体薄膜を
積層して形成する半導体装置の製法において、該透明導
電膜と接する半導体薄膜の初期膜の部分が、少なくとも
フルオロシランおよびIII族化合物の放電分解により形
成されることを特徴とする半導体装置の製法、であり、
好ましくは、該III族化合物は三弗化硼素(BF3)または
ジボラン(B2H6)であり、また好ましくは該フルオロシ
ランがSiH4-nFn(n=1〜4)であらわされるフルオロ
モノシランまたはSi2F6なるフルオロジシランであり、
さらに好ましくは、かかるフルオロシランおよびIII族
化合物からなる混合ガスを放電により分解し、加熱され
た透明導電膜付透光性基板上に半導体薄膜を形成する半
導体装置の製法、を要旨とするものである。 本発明においては、透明導電膜と接する半導体薄膜の
初期膜の部分を形成するに際し、主原料として、フルオ
ロシランを使用することを最も特徴としているが、使用
するフルオロシランとしては該フルオロシランがSiH4-n
Fn(n=1〜4)であらわされるフルオロモノシランま
たはSi2F6なるフルオロジシランであり特に好ましくはS
iH2F2が有効に用いられる。 また、この際用いられるIII族の化合物としては、III
族の弗素化合物または水素化合物が好ましく、具体的な
示例としては三弗化硼素(BF3)またはジボラン(B
2H6)、アルシン(AsH3)などである。 なお、本発明において、半導体薄膜の形成条件で基板
温度は約200℃前後と低く出来るので、基板としては、
この温度条件に耐える多数の各種透明導電膜付透光性基
板が有効に用いられる。 本発明においては、フルオロシランとIII族化合物に
対して好ましい流量比の範囲はつぎの通りである。すな
わち、III族化合物/フルオロシランシラン=1x10-7
0.1で充分である。 フルオロシランおよびIII族化合物からなる混合ガス
の形成方法は臨界的な因子ではなく特に限定されるもの
ではない。例えば、該形成装置外で予め混合したガスを
導入することや、該形成装置内で、上記の希釈度合を満
足すべくIII族の化合物を混合することのいずれも有用
である。もちろん、III族の化合物を添加混合されたフ
ルオロシランを使用することはなんら支障がない。 本発明における放電分解は、高周波グロー放電、直流
グロー放電、マイクロ波放電などを有効に利用すること
ができる。 本発明において、放電分解に用いる電力を発生する電
源を臨界的な条件ではなく特に限定されるものではな
い。具体的示例としては、高周波電源、直流高圧電源、
マイクロ波電源などが有用である。 本発明において、放電分解時の混合ガス圧力や供給電
力については特に臨界的に限定される条件はない。これ
らの条件は該半導体薄膜の成長速度に影響を与えるもの
であり、成長速度に応じて基板温度を適宜変更すること
で透明導電膜と半導体薄膜との界面における電気的な特
性の優れた半導体薄膜を効果的に形成することができ
る。 〔作用〕 本発明においては、フルオロシランおよびIII族化合
物の混合ガスを放電により分解し、透明導電膜と接する
半導体薄膜の初期膜を形成することにより、反応系内に
存在する弗素系の分子またはイオン、ラジカルにより透
明導電膜の表面および/または内部を保護し、前述の透
明導電膜に対する損傷を極力少なくすることにより、加
熱された透明導電膜付透光性基板上に該主表面と半導体
薄膜との界面における電気的な特性の優れた半導体薄膜
を形成することが出来るのである。 [発明を実施するための好ましい形態] つぎに本発明の実施の態様について記す。放電手段、
基板導入手段、基板保持手段、基板加熱手段、ガス導入
手段、真空排気手段を少なくとも有する薄膜形成装置内
に洗浄およびまたはエッチングにより表面を清浄にした
透明導電膜付透光性基板を設置し真空排気下基板を100
〜400℃に加熱する。原料ガスはフルオロシランに対す
るIII族化合物の流量比を1X10-7〜0.1とし、該装置に供
給される。真空排気手段で該装置内の圧力を1Torr以下
として放電を開始する。放電開始と共に薄膜の形成が始
まるので成膜速度を考慮にいれて必要膜厚になる時間に
おいて放電を止める。また、膜厚モニターによって膜厚
を計測しつつ、成膜時間を決めることもできる。斯し
て、初期膜を形成した後は、常法により、通常の薄膜を
形成し、半導体装置とすればよい。すなわち、モノシラ
ン、ジシラン等のシラン系ガスおよび/または炭化水
素、III族化合物(B2H6)、V族化合物(PH3)を用い
て、p型半導体薄膜、i型半導体薄膜、n型半導体薄膜
の順で、通常の方法により積層すればよいのである。 〔発明の効果〕 本発明において得られる透明導電膜と半導体薄膜間の
界面の特性に優れた半導体薄膜は基板の温度が300℃以
下の低温、さらには200℃以下という極めて低い温度に
おいても形成されるものである。高集積化のために、半
導体薄膜や半導体装置の低温形成技術が熱望されている
半導体装置の製造分野に対して、本発明は極めて有用な
技術を提供するものである。 [実施例] 高周波電力導入手段および放電電極、基板導入取り出
し手段、基板保持手段、基板加熱手段、ガス導入手段、
真空排気手段、基板導入取り出し室を設備された薄膜形
成装置を用いて本発明を実施した。基板導入取り出し手
段を用いて膜付けのための基板であるところの洗浄済の
酸化スズ(SnO2)付きガラス基板を基板導入取り出し室
から基板導入取り出し手段を用いて導入し基板保持手段
に設置した。真空排気手段で真空排気しつつ基板加熱手
段により該基板を250℃に加熱した。ジフルオロシラン/
III族化合物を1/1X10-3の流量比で導入し、真空排気手
段に設備されている圧力調節機構で薄膜形成装置内の圧
力を0.3Torrに調節保持した。基板の温度および薄膜形
成装置内の圧力が一定となった時、高周波電力導入手段
により放電電極20Wの高周波電力を印加しグロー放電を
開始した。膜厚が約20〜50Aになった時に放電を一旦停
止する。以上のごとくして初期膜が形成された後は、ひ
きつづいて、さらに、シラン系ガス(モノシラン(Si
H4)またはジシラン(Si2H6)および/または炭化水
素、III族化合物(B2H6)、V族化合物(PH3)を用い
て、p型半導体薄膜、i型半導体薄膜、n型半導体薄膜
の順で、通常の方法により積層した。冷却後基板を取り
出して観察したところ、基板面は曇りの全くない鏡面で
あった。さらに、裏面電極として金属を蒸着して半導体
装置とした。 該半導体装置の光電変換特性を測定したところ、短絡
電流値の大幅な改善が認められた。すなわち、17mA/cm2
以上の電流が得られた。
Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a semiconductor thin film at a low temperature, which is excellent in improving interface characteristics between a transparent substrate with a transparent conductive film and a semiconductor thin film. [Background Art] A crystalline or amorphous semiconductor thin film is used in a semiconductor device. These are usually formed on a substrate. As such a substrate, a substrate with a transparent conductive film whose surface is cleaned by cleaning and / or etching is used as a material having electrodes required for a semiconductor device. Is often done. For example, in an amorphous solar cell, a transparent conductive film is used as an electrode on the incident light side. However, in a conventional glow discharge forming method mainly using a silane-based gas (Si m H 2m + 2 (m = 1 to 3)) such as monosilane or disilane, the transparent conductive film is not suitable for forming a semiconductor thin film. The glow discharge caused damage, reduced transparency and increased electrical resistance,
This means that it is a factor that adversely affects the electrical properties of the obtained semiconductor device. For example, an amorphous solar cell has a significant problem that its photoelectric conversion characteristics are significantly reduced. In order to solve such a problem, there has conventionally been a strong demand for a technique for forming a semiconductor thin film having excellent electrical characteristics while avoiding damage to the surface of the transparent conductive film at the interface between the substrate and the semiconductor thin film. The present inventor has studied the discharge decomposition of a raw material gas mainly composed of fluorosilane based on such a viewpoint. As a result, a transparent conductive film was formed by forming an initial film of amorphous silicon using fluorosilane as a main raw material. It has been found that a semiconductor device can be formed without causing a decrease in electric resistance and transparency of the film, and that a p-type doping is possible by coexisting a group III compound in the reaction gas. The present invention has been made based on such new and important findings first discovered by the present inventors. [Disclosure of the Invention] The present invention relates to a method for manufacturing a semiconductor device in which a transparent conductive film and a semiconductor thin film are formed on a light-transmitting substrate. A method for producing a semiconductor device, characterized by being formed by discharge decomposition of silane and a group III compound,
Preferably, the III compound is boron trifluoride (BF 3) or diborane (B 2 H 6), also represented by preferably the fluoro silane SiH 4-n F n (n = 1~4) A fluorodisilane which is fluoromonosilane or Si 2 F 6 ,
More preferably, a method of manufacturing a semiconductor device in which a mixed gas comprising such fluorosilane and a group III compound is decomposed by electric discharge and a semiconductor thin film is formed on a heated transparent conductive film-attached light-transmitting substrate. is there. In the present invention, when forming the initial film portion of the semiconductor thin film in contact with the transparent conductive film, the most characteristic feature is that fluorosilane is used as a main material, but the fluorosilane used is SiH 4-n
F n (n = 1~4) fluoro monosilane or Si 2 F 6 becomes fluoro disilane represented by particularly preferably S
iH 2 F 2 is used effectively. In addition, as the Group III compound used in this case, III
A group fluorine compound or hydrogen compound is preferable, and specific examples include boron trifluoride (BF 3 ) or diborane (B
2 H 6), arsine (AsH 3), and the like. In the present invention, the substrate temperature can be as low as about 200 ° C. under the conditions for forming the semiconductor thin film.
A large number of light-transmitting substrates with transparent conductive films that can withstand this temperature condition are effectively used. In the present invention, the preferred range of the flow ratio for the fluorosilane and the group III compound is as follows. That is, group III compound / fluorosilane silane = 1 × 10 −7
0.1 is sufficient. The method for forming the mixed gas comprising fluorosilane and the group III compound is not a critical factor and is not particularly limited. For example, it is useful to introduce a gas mixed in advance outside the forming apparatus or to mix a group III compound in the forming apparatus so as to satisfy the above-mentioned dilution degree. Of course, there is no problem in using a fluorosilane mixed with a Group III compound. In the discharge decomposition according to the present invention, high-frequency glow discharge, DC glow discharge, microwave discharge, and the like can be effectively used. In the present invention, the power source for generating the power used for the discharge decomposition is not a critical condition and is not particularly limited. Specific examples include a high-frequency power supply, a DC high-voltage power supply,
A microwave power supply or the like is useful. In the present invention, there is no particular critical condition for the pressure of the mixed gas and the supply power during the discharge decomposition. These conditions affect the growth rate of the semiconductor thin film, and by appropriately changing the substrate temperature according to the growth rate, the semiconductor thin film having excellent electrical characteristics at the interface between the transparent conductive film and the semiconductor thin film. Can be effectively formed. [Action] In the present invention, a mixed gas of fluorosilane and a group III compound is decomposed by electric discharge to form an initial film of a semiconductor thin film in contact with the transparent conductive film, thereby forming a fluorine-based molecule or a fluorine-based molecule existing in the reaction system. By protecting the surface and / or the inside of the transparent conductive film with ions and radicals and minimizing the damage to the transparent conductive film, the main surface and the semiconductor thin film are formed on the heated transparent conductive film-attached light-transmitting substrate. This makes it possible to form a semiconductor thin film having excellent electrical characteristics at the interface with the substrate. [Preferred Embodiments for Carrying Out the Invention] Next, embodiments of the present invention will be described. Discharging means,
A light-transmitting substrate with a transparent conductive film whose surface is cleaned by cleaning and / or etching is evacuated in a thin film forming apparatus having at least a substrate introduction means, a substrate holding means, a substrate heating means, a gas introduction means, and a vacuum evacuation means. Lower substrate 100
Heat to ~ 400 ° C. The raw material gas is supplied to the apparatus at a flow ratio of the group III compound to fluorosilane of 1 × 10 −7 to 0.1. The discharge is started by reducing the pressure in the apparatus to 1 Torr or less by a vacuum exhaust means. Since the formation of the thin film starts with the start of the discharge, the discharge is stopped at the time when the required film thickness is reached in consideration of the film forming speed. Further, the film formation time can be determined while measuring the film thickness by the film thickness monitor. After forming the initial film in this manner, a normal thin film may be formed by a conventional method to form a semiconductor device. That is, a p-type semiconductor thin film, an i-type semiconductor thin film, and an n-type semiconductor using a silane-based gas such as monosilane and disilane and / or a hydrocarbon, a group III compound (B 2 H 6 ), and a group V compound (PH 3 ). What is necessary is just to laminate | stack by a normal method in order of a thin film. [Effects of the Invention] A semiconductor thin film having excellent properties at the interface between the transparent conductive film and the semiconductor thin film obtained in the present invention is formed at a substrate temperature as low as 300 ° C or lower, and even at an extremely low temperature of 200 ° C or lower. Things. The present invention provides an extremely useful technique in the field of semiconductor device manufacturing in which a low-temperature formation technique of a semiconductor thin film and a semiconductor device is highly desired for high integration. [Example] High-frequency power introduction means and discharge electrode, substrate introduction / extraction means, substrate holding means, substrate heating means, gas introduction means,
The present invention was implemented using a thin film forming apparatus provided with a vacuum exhaust unit and a substrate introduction / extraction chamber. A cleaned glass substrate with tin oxide (SnO 2 ), which is a substrate for film formation using the substrate introduction / extraction means, was introduced from the substrate introduction / extraction chamber using the substrate introduction / extraction means, and was set on the substrate holding means. . The substrate was heated to 250 ° C. by the substrate heating means while evacuation was performed by the evacuation means. Difluorosilane /
A group III compound was introduced at a flow rate of 1/1 × 10 −3 , and the pressure in the thin film forming apparatus was adjusted to 0.3 Torr by a pressure adjusting mechanism provided in a vacuum evacuation means. When the temperature of the substrate and the pressure in the thin film forming apparatus became constant, high frequency power of the discharge electrode 20W was applied by the high frequency power introducing means to start glow discharge. When the film thickness reaches about 20 to 50 A, the discharge is temporarily stopped. After the initial film is formed as described above, the silane-based gas (monosilane (Si
H 4 ) or disilane (Si 2 H 6 ) and / or hydrocarbon, a group III compound (B 2 H 6 ), or a group V compound (PH 3 ) using a p-type semiconductor thin film, an i-type semiconductor thin film, and an n-type The semiconductor thin films were stacked in the usual order by an ordinary method. When the substrate was taken out after cooling and observed, the substrate surface was a mirror surface without any fogging. Further, a metal was deposited as a back electrode to obtain a semiconductor device. When the photoelectric conversion characteristics of the semiconductor device were measured, a significant improvement in the short-circuit current value was recognized. That is, 17 mA / cm 2
The above current was obtained.

Claims (1)

(57)【特許請求の範囲】 1.透光性基板上に透明導電膜と半導体薄膜を積層して
形成する半導体装置の製法において、該透明導電膜と接
する半導体薄膜の初期膜の部分を、少なくともフルオロ
シランおよびIII族化合物の放電分解により形成し、さ
らにシラン系ガスおよび/または炭化水素、III族化合
物、V族化合物を用いてp型半導体薄膜、i型半導体薄
膜およびn型半導体薄膜の順で積層することを特徴とす
る半導体装置の製法。 2.III族化合物が三弗化硼素(BF3)またはジボラン
(B2H6)である特許請求の範囲第1項記載製法。 3.フルオロシランがSiH4-nFn(n=1〜4)であらわ
されるフルオロモノシランまたはSi2F6なるフルオロジ
シランである特許請求の範囲第1項記載の製法。 4.フルオロシランおよびIII族化合物からなる混合ガ
スを放電により分解し、加熱された透明導電膜付透光性
基板上に半導体薄膜の初期膜を形成する特許請求の範囲
第1項記載の製法。
(57) [Claims] In a method for manufacturing a semiconductor device in which a transparent conductive film and a semiconductor thin film are stacked over a light-transmitting substrate, a part of the initial film of the semiconductor thin film that is in contact with the transparent conductive film is formed by at least discharge decomposition of fluorosilane and a group III compound. Forming a p-type semiconductor thin film, an i-type semiconductor thin film, and an n-type semiconductor thin film using a silane-based gas and / or a hydrocarbon, a group III compound, and a group V compound in this order. Manufacturing method. 2. 2. The method according to claim 1, wherein the Group III compound is boron trifluoride (BF 3 ) or diborane (B 2 H 6 ). 3. Preparation of fluorosilane SiH 4-n F n (n = 1~4) fluoro monosilane or Si 2 F 6 Scope first claim of claims is fluoro disilane represented. 4. 2. The method according to claim 1, wherein a mixed gas comprising fluorosilane and a group III compound is decomposed by electric discharge to form an initial semiconductor thin film on the heated translucent substrate with a transparent conductive film.
JP62168204A 1987-07-06 1987-07-06 Semiconductor device manufacturing method Expired - Fee Related JP2728874B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62168204A JP2728874B2 (en) 1987-07-06 1987-07-06 Semiconductor device manufacturing method

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JPS5727015A (en) * 1980-07-25 1982-02-13 Agency Of Ind Science & Technol Manufacture of silicon thin film
JPS58143589A (en) * 1982-02-19 1983-08-26 Kanegafuchi Chem Ind Co Ltd Silicon base semiconductor
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