JP2004206998A - Cell and cell plate for solid oxide fuel cell, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cell and a cell plate for a fuel cell capable of increasing an area ratio of an aperture where to stack layers of a battery element to a substrate and enhancing power generation output by increasing an effective power generating area without impairing the strength of the substrate in a solid oxide fuel cell in which the substrate supports the cell element composed of a solid oxide electrolyte and electrodes sandwiching the same. <P>SOLUTION: The aperture 5 is formed in the silicon substrate 1 to have an aperture angle α of 90° or more formed between the surface of the substrate and a wall face of the aperture 5 as taken in the cross section of the aperture 5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３１】
また、上記犠牲層の形成に際して、例えば酸化珪素や窒化ケイ素層を成膜あるいはイオン打ち込みによってヒドラジンなどの異方性エッチング液に可溶な犠牲層とすることが望ましく、これによって、基材の下面側の異方性エッチング、当該犠牲層の等方性エッチング、及び基材上面側の異方性エッチングを１種類の異方性エッチング液によって連続的に行うことができるようになり、製造工程の簡略化が達成できることになる。
【００３２】
さらに、本発明の製造方法においては、エッチングに際して、その時点で基板上に成膜されている電池要素を、例えばＰＳＧ（りんケイ酸ガラス）等によってマスキングすることが望ましく、これによって各電池要素の積層界面がエッチング液に曝されることがなくなり、電極層の反応抵抗を軽減して出力の向上を図ることができる。
【００３３】
本発明の上記固体酸化物形燃料電池用セル、あるいは固体酸化物形燃料電池用セル板を用いて燃料電池スタックを構成することができ、これによって発電有効面積及びセル数が大きなものとなり、スタックとしての発電出力が増大することになる。
また、本発明の上記固体酸化物形燃料電池用セル、あるいは固体酸化物形燃料電池用セル板は、燃料電池システムに適用することができ、例えば燃料ガス及び酸化剤ガス（空気）の供給量などを制御する制御部と、ガス供給部と共に組み込み、これらガス供給量を最適な状態に制御するよになすことによって、システム全体の発電効率をさらに向上させることが可能になる。
【００３４】
【実施例】
以下、本発明を実施例に基づいて具体的に説明する。なお、本発明は、これらの実施例のみに限定されることはない。
【００３５】
（実施例１）
基板１として、（１００）面を表面とする板厚０．５ｍｍの単結晶シリコン基板を使用し、まず図２（ａ）に示すように、上記シリコン基板１の表面（図中上面）に、レジスト１１を塗布した。次いで、フォトリソグラフィによってパターニングし、図２（ｂ）に示すように、一辺２ｍｍの正方形である犠牲層形成用のイオン注入口１１ａを形成した。
【００３６】
次に、図２（ｃ）に示すように、上記注入口１１ａから高濃度のＡｒイオンを加速電圧７５ｋｅＶ、注入量１×１０^１５／ｃｍ^２で注入することによって、当該部分を非結晶化して、基板１の表面に犠牲層１２を形成したのち、図２（ｄ）に示すように、有機溶媒あるいは適当なエッチング液を用いて、レジスト１１を除去した。
さらに、図２（ｅ）に示すように、シリコン基板１の上下面に、ＣＶＤ法によってＳｉ_３Ｎ_４層から成る絶縁層６を成膜した。なお、当該Ｓｉ_３Ｎ_４層は、開口部形成時のエッチングに際して、マスク層としても機能するものであって、基板１の下面側Ｓｉ_３Ｎ_４層６については、一辺３ｍｍである正方形の開口部形成用のエッチング口１３を形成している。なお、犠牲層１２の形成については、Ｓｉ_３Ｎ_４層６を形成してからマスクし、イオン注入することもでき、この場合にはＳｉ単結晶基板に対し引張り応力の大きいＳｉ_３Ｎ_４層の結合がイオン注入により切れて、引張り応力が減少することから、開口部に成膜する電解質層の強度が向上する効果をも期待することができる。
【００３７】
そして、基板１の上面側に成膜されたＳｉ_３Ｎ_４層６の上に、図２（ｆ）に示すように、空気極としてのＬＳＣ（Ｌａ_０．８Ｓｒ_０．２ＣｏＯ_３）を１０ＰａのＡｒ中における出力２００ＷのＲＦスパッタ法によって０．５μｍの厚さに成膜して下部電極層４とすると共に、この空気極４の上に、８ＹＳＺ（８ｍｏｌ％Ｙ_２Ｏ_３添加ＺｒＯ_２）から成る固体電解質を１ＰａのＡｒ中における出力２００ＷのＲＦスパッタ法によって２μｍの厚さに成膜して、図２（ｇ）に示すように電解質層２とした。
さらに、この電解質層２の上に、ＮｉＯと８ＹＳＺの原料粉を１：１に混合して焼成したターゲットを用いたＲＦスパッタ法（２００Ｗ、１Ｐａ（Ａｒ））によって、図２（ｈ）に示すように、燃料極としてのＮｉＯ−８ＹＳＺサーメットを０．５μｍの厚さに成膜して、上部電極層３とした。
【００３８】
そして次に、図３（ｉ）に示すように、基板１の上面側Ｓｉ_３Ｎ_４層６の上に、ＰＳＧ（りんケイ酸ガラス）から成るマスク材１４をＣＶＤ成膜し、Ｓｉ_３Ｎ_４層６の上に成膜された電池要素２，３，４を覆うようにマスキングを施したのち、図３（ｊ）に示すように、基板１の裏面（下面）側から、ヒドラジン系エッチング液を用いて、先に形成した犠牲層１２に到達するまでシリコン基板１の下面側を異方性エッチングし、続いて、図３（ｋ）に示すように犠牲層１２を上記エッチング液による等方性エッチングによって除去した。さらに、続いてシリコン基板１の上面側を同じエッチング液によって異方性エッチングした。これによって、シリコン材の（１１１）面でエッチングが停止し、図３（ｌ）に示すように、開口角αが鈍角である開口部５が形成される。
【００３９】
次いで、図３（ｍ）に示すように、基板１の下面側からＣＦ_４を用いたプラズマエッチングを行い、空気極４の下面に接しているＳｉ_３Ｎ_４層部分と、基板１の下面の開口部５の周囲に付着しているＳｉ_３Ｎ_４層を除去したのち、最後にＨＦ‐ＨＮＯ_３エッチング液によりマスク材１４を除去することにより、固体酸化物形燃料電池用セルが得られる。
【００４０】
当該実施例に係わる製造方法によれば、電池要素４，２，３を連続的に形成することができると共に、鈍角の開口角αを有する開口部５のエッチングを同一の異方性エッチング液によって連続的に行うことができ工程の簡略化が可能である。さらに、開口部５のエッチングに先立って成膜された電池要素にマスキングを施すようにしているので、電池要素の積層界面がエッチング液に侵されることがなく、電極層の反応抵抗が減少して発電出力を向上させることができる。
【００４１】
（実施例２）
次に、本発明の第２の実施例として、基板１の上下両面側から電池要素を成膜する方法について説明する。
先ず、（１００）面を表面とする板厚０．５ｍｍの単結晶シリコン基板を使用し、図４（ａ）〜（ｅ）に示すように、上記実施例１と同様の手順によって、犠牲層１２及び絶縁層６を形成した。
【００４２】
次に、図４（ｆ）に示すように、基板１の上面側に成膜された絶縁層６であるＳｉ_３Ｎ_４層の上に、上記実施例１と同様に、８ＹＳＺから成る固体電解質を同様のＲＦスパッタ法によって成膜して電解質層２とした。
【００４３】
そして、図４（ｇ）に示すように、基板１の裏面（下面）側から、ヒドラジン系エッチング液を用いて、シリコン基板１の下面側を異方性エッチングし、続いて、図４（ｈ）に示すように犠牲層１２を上記エッチング液による等方性エッチングによって除去し、さらにシリコン基板１の上面側を同じエッチング液によって異方性エッチングし、図５（ｉ）に示すように、上記実施例１と同様の開口部５を形成した。
【００４４】
次いで、図５（ｊ）に示すように、基板１の下面側からＣＦ_４を用いたプラズマエッチングにより、電解質層２の下面のＳｉ_３Ｎ_４層部分と、基板１の下面の開口部５の周囲に付着しているＳｉ_３Ｎ_４層を除去したのち、図５（ｋ）に示すように、電解質層２の上に空気極としてのＬＳＣを同様のＲＦスパッタ法（２００Ｗ、１０Ｐａ（Ａｒ））によって成膜して上部電極層３とした。
そして、最後に基板１の下面側から、ＲＦスパッタ法による自公転斜めスパッタリングによって燃料極としてのＮｉＯ−８ＹＳＺサーメットを電解質層２の下面上に成膜して下部電極層４とし、図５（ｍ）に示すように、固体酸化物形燃料電池用セルを完成させた。
【００４５】
当該実施例に係わる製造方法によれば、上記実施例と同様に、鈍角の開口角αを有する開口部５のエッチングを同一の異方性エッチング液によって連続的に行うことができると共に、空気極及び燃料極の集電を基板１の表面側と裏面側とに分けることができ、集電のパターニングが簡単なものなり、セルの有効面積がさらに増加し、出力を一層向上させることができる。
【００４６】
（実施例３）
本発明の第３の実施例においても、上記実施例２と同様に、基板１の上下両面側から電池要素を成膜する方法について説明する。
同様に、（１００）面を表面とする板厚０．５ｍｍの単結晶シリコン基板を使用し、図６（ａ）〜（ｆ）に示すように、上記実施例２と同じ手順により、犠牲層１２及び絶縁層６を形成し、絶縁層の上に８ＹＳＺから成る固体電解質を同様のＲＦスパッタ法によって成膜して電解質層２とした。
【００４７】
次に、図６（ｇ）に示すように、電解質層２の上に、空気極としてのＬＳＣを同様のＲＦスパッタ法によって成膜して上部電極層３としたのち、図６（ｈ）に示すように、基板１の上面側に成膜されたＳｉ_３Ｎ_４層６の上に、ＰＳＧから成るマスク材１４をＣＶＤ成膜し、Ｓｉ_３Ｎ_４層６の上に成膜された電解質層２及び空気極３を覆うようにマスキングを施した。
【００４８】
ＰＳＧによるマスキングを電池要素に施した後、図７（ｉ）〜（ｋ）に示すように、上記実施例と同様のエッチングによって開口部５を形成し、図７（ｌ）に示すように、電解質層２の裏面側及び基板１の下面側のＳｉ_３Ｎ_４層６を同様に除去したのち、図７（ｍ）のように、ＨＮＯ_３を主成分とするエッチング液によってマスク材１４を除去した。
そして、基板１の下面側から、ＲＦスパッタ法による自公転斜めスパッタリングによって燃料極としてのＮｉＯ−８ＹＳＺサーメットを電解質層２の下面上に成膜して下部電極層４とし、図７（ｎ）に示すように、固体酸化物形燃料電池用セルを完成させた。
【００４９】
当該実施例に係わる製造方法によれば、上記実施例と同様に、鈍角の開口角αを有する開口部５のエッチングを同一の異方性エッチング液によって連続的に行うことができると共に、集電を基板１の表面側と裏面側とに分けることによって集電のパターニングが簡単なものとすることができ、セルの有効面積の増加によって、出力をさらに向上させることができ、さらに、エッチングに際して電池要素にマスキングを施すようにしているので、空気極の積層界面がエッチング液に曝されることがなく、反応抵抗が減少して発電出力を向上させることができる。
【００５０】
（実施例４）
本発明の第４の実施例として、基板１の犠牲層６を成膜する場合について説明する。
まず、基板１として、（１００）面を表面とする板厚０．５ｍｍの単結晶シリコン基板を使用し、図８（ａ）に示すように、上記シリコン基板１の表面に、レジスト１１を塗布し、フォトリソグラフィによってパターニングすることによってし、図８（ｂ）に示すように、犠牲層成膜用の開口１１ｂを形成した。
【００５１】
次に、図８（ｃ）に示すように、上記レジスト１１の開口１１ｂの内側と、その周囲に、１ＰａのＡｒ中における出力３００ＷのＤＣスパッタ法によってＡｌ層を０．５μｍの厚さに成膜して犠牲層１２を形成したのち、図８（ｄ）に示すように、有機溶媒あるいはエッチング液を用いてレジスト１１を除去し、犠牲層１２のみを基板１の上に残した。なお、このとき、シリコン基板１の表面を削って窪みを設けた状態でＡｌ成膜を行った後、表面を研磨することによって犠牲層１２のレベルを基板１と同じにすることができ、次工程において絶縁層６を平坦に形成することができる。
【００５２】
次いで、図８（ｅ）に示すように、シリコン基板１の上下面に、ＣＶＤ法によってＳｉ_３Ｎ_４層から成る絶縁層６を成膜すると共に、基板１の下面側については、開口部形成用のエッチング口１３を形成した。次いで、図８（ｆ）に示すように、基板１の上面側に成膜されたＳｉ_３Ｎ_４層６の上に、上記実施例２，３と同様に、８ＹＳＺから成る固体電解質をＲＦスパッタ法によって同様に成膜して電解質層２とした。
【００５３】
そして、図８（ｇ）に示すように、基板１の下面側から、ヒドラジン系エッチング液を用いて、シリコン基板１の下面側を異方性エッチングすることにより、犠牲層１２に達する穴を形成した後、塩酸を用いて犠牲層１２の等方性エッチングを行い、図８（ｈ）に示すように犠牲層１２を除去した。さらにシリコン基板１の上面側をヒドラジン系エッチング液によって異方性エッチングし、図９（ｉ）に示すように、実施例２，３と同様の開口部５を形成した。
【００５４】
次いで、図９（ｊ）に示すように、基板１の下面側からＣＦ４を用いたプラズマエッチングにより、電解質層２の裏面部分と、基板１の下面に付着しているＳｉ_３Ｎ_４層６を除去したのち、図９（ｋ）に示すように、電解質層２の上に空気極としてのＬＳＣを同様のＲＦスパッタ法（２００Ｗ、１０Ｐａ（Ａｒ））によって成膜して上部電極層３とした。
そして、最後に基板１の下面側から、ＲＦスパッタ法による自公転斜めスパッタリングによって燃料極としてのＮｉＯ−８ＹＳＺサーメットを電解質層２の下面上に成膜して下部電極層４とし、図９（ｌ）に示すような固体酸化物形燃料電池用セルを得た。
【００５５】
（実施例５）
上記実施例２に示した構造のセルを複数個配列したセル板を作製すると共に、当該セル板を重ねて燃料電池スタックを組立て、鋭角の開口角αを有する従来タイプのセル板からなる燃料電池との性能比較を行った。
【００５６】
すなわち、（１００）面を表面とする１００ｍｍ×１００ｍｍ×０．５ｍｍの単結晶シリコン基板１を使用し、この基板１に、図１０に示すように、実施例２と同じ構造を有し、セルサイズ、すなわち電池要素の有効積層サイズが２ｍｍ四方の単セルを２次元的に配列した。当該セル板の端縁部からそれぞれ５ｍｍをシールしろとし、基板１の裏面側におけるセル間距離を最低０．５ｍｍとすると、開口部５の開口角αが鈍角である実施例２のセル構造を採用することにより、基板１の表面側におけるセル間距離を１ｍｍとすることができ、基板１の１辺に沿って３０個、合計９００個の単セルを配設することができた。
【００５７】
このようなセル板１００枚を用い、図１１に示すように、間に板厚０．５ｍｍ、溝深さがそれぞれ０．２ｍｍのセパレータを挟んで積層することにより、燃料電池スタックを作製すると、高さが１００．５ｍｍとなった。
このような燃料電池セルにおいては、出力密度が０．２Ｗ／ｃｍ^２であることが判っているので、上記セル板１枚当たり７．２Ｗ（０．２×０．２×９００×０．２）、スタック全体では７２０Ｗの出力が得られることになる。
【００５８】
これに対し、犠牲層を形成することなく、Ｓｉ_３Ｎ_４から成る絶縁層を形成し、８ＹＳＺから成る電解質層を成膜したのち、異方性エッチングにより開口部を形成し、次いで、ＬＳＣからなる空気極およびＮｉＯ−８ＹＳＺサーメットからなる燃料極を順次成膜して製造した従来のセル構造においては、開口部の開口角αが鋭角となることから、シールしろを５ｍｍとすると、図１３に示すように、基板裏面側のセル間距離を０．５ｍｍとしても、基板表面側におけるセル間距離が３．２１ｍｍとなってしまい、単セルを１７列しか配列することができず（合計２８９個）、したがってセル板１枚当たりの出力が２．３１Ｗ（０．２×０．２×２８９×０．２）、スタック全体でも２３１Ｗの出力が得られるに過ぎないことになる。
【００５９】
（実施例６）
図１２は、本発明の固体酸化物形燃料電池システムの構成例を示すブロック図であって、当該燃料電池システムは、本発明の上記燃料電池セル又はセル板を用いて成る燃料電池スタックと、燃料電池スタックに水素や炭化水素などの燃料ガスを供給する燃料供給部と、燃料電池スタックに空気を供給する空気供給部と、これら燃料電池スタック、燃料供給部、空気供給部に各種センサを介して接続された制御装置から主に構成されている。
【００６０】
上記システムにおいては、制御装置がそれぞれのセンサによって検出された燃料電池スタックの温度や、供給ガス成分、排出ガス成分、電池出力などに応じて、温度や燃料供給量、空気供給量を最も効率良く発電が行われるように制御するようになっているので、上記燃料電池スタックの単位体積あたりの発電出力の向上と併せて、システム全体の発電効率をさらに向上させることができる。
【００６１】
【発明の効果】
以上説明したように、本発明によれば、（１００）面を表面とする単結晶シリコン基板に形成された開口部を塞ぐように電池要素が積層された構造の個体酸化物形燃料電池用セル又はセル板において、基板表面と開口部の壁面とのなす開口角αを９０°以上としたことから、開口角αが鋭角であった従来の燃料電池用セル及びセル板と比較して、基板の強度を低下させることなく電池要素の有効発電面積を広くすることができ、単位体積あたりの発電出力を大幅に向上させることができる向上、燃料電池の小型化への対応が可能なものとなる。
また、本発明の製造方法によれば、シリコン基板の電池要素の積層面側に犠牲層を形成した上で、反積層面側から基板を異方性エッチングし、上記犠牲層を等方性エッチングして除去したのち、基板の積層面側を異方性エッチングすることにより、開口角αが９０°以上の開口部を形成することができる。
【図面の簡単な説明】
【図１】本発明の固体酸化物形燃料電池用セルにおける開口部の断面形状例を示す断面図である。
【図２】本発明の第１の実施例による固体酸化物形燃料電池用セルの製造手順の前半を示す工程図である。
【図３】本発明の第１の実施例による固体酸化物形燃料電池用セルの製造手順の後半を示す工程図である。
【図４】本発明の第２の実施例による固体酸化物形燃料電池用セルの製造手順の前半を示す工程図である。
【図５】本発明の第２の実施例による固体酸化物形燃料電池用セルの製造手順の後半を示す工程図である。
【図６】本発明の第３の実施例による固体酸化物形燃料電池用セルの製造手順の前半を示す工程図である。
【図７】本発明の第３の実施例による固体酸化物形燃料電池用セルの製造手順の後半を示す工程図である。
【図８】本発明の第４の実施例による固体酸化物形燃料電池用セルの製造手順の前半を示す工程図である。
【図９】本発明の第４の実施例による固体酸化物形燃料電池用セルの製造手順の後半を示す工程図である。
【図１０】本発明の固体酸化物形燃料電池セル板の形状を示す斜視図及び断面図である。
【図１１】（ａ） 本発明の固体酸化物形燃料電池スタックの形状を示す断面図である。
（ｂ） 図１１（ａ）に示したセパレータの形状を示す斜視図である。
（ｃ） 図１１（ａ）に示したスタックの斜視図である。
【図１２】本発明の固体酸化物形燃料電池システムの構成例を示すブロック図である。
【図１３】従来の固体酸化物形燃料電池セル板の形状を示す斜視図及び断面図である。
【符号の説明】
１ シリコン基板
２ 電解質層
３ 上部電極層
４ 下部電極層
５ 開口部
６ 絶縁層
１２ 犠牲層
１４ マスキング[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a solid oxide fuel cell (SOFC) comprising a battery element comprising a solid oxide electrolyte and both electrodes (air electrode and fuel electrode) sandwiching the electrolyte, and a substrate supporting the same. In particular, it is possible to increase the opening area of the opening of the supporting substrate on which the battery element is formed, in other words, it is possible to increase a power generation effective area by reducing a useless space between the openings, thereby improving the power generation output. The present invention relates to a cell and a cell plate for a solid oxide fuel cell, and a method for producing the fuel cell and the cell plate.
[0002]
[Prior art]
A fuel cell is a device that converts chemical energy into electric energy by an electrochemical reaction.In the case of a solid oxide fuel cell, each layer of a fuel electrode, a solid electrolyte, and an air electrode is arranged, laminated and stacked. By constructing three layers and using this as the power generation section of the fuel cell, a fuel gas such as hydrogen or hydrocarbon is supplied from the outside to the fuel electrode side, and an oxidizing gas such as air is supplied to the air electrode, Generally, this type of battery operates at about 1000 ° C.
[0003]
In general, a solid oxide of a solid oxide fuel cell is required to have a gas-impermeable property as well as an ion-permeable property and an ion-permeable property. ₂ O ₃ ), Neodymium oxide (Nd ₂ O ₃ ), Samarium oxide (Sm ₂ O ₃ ), Gadolinium oxide (Gd ₂ O ₃ ), Scandium oxide (Sc ₂ O ₃ ) And ceria (CeO) ₂ ) -Based solid solution, bismuth oxide and lanthanum gallate (LaGaO) ₃ ) Is used.
[0004]
It is known that the conductivity of such a solid electrolyte is about one digit lower than the conductivity of the electrolyte in a phosphoric acid fuel cell (PAFC) or a molten carbonate fuel cell (MCFC). . In general, since the electrical resistance of the electrolyte part is a power generation loss, it is important to reduce the membrane resistance as much as possible by thinning the solid electrolyte in order to improve the power generation output density. Since a certain amount of area is required to secure the function of the solid electrolyte fuel cell, a cell structure in which an electrolyte membrane is formed on a support having mechanical strength is adopted. I have.
[0005]
For example, in Patent Document 1, a substrate having an opening penetrating from the upper surface to the lower surface is used, and an upper electrode layer is laminated on all or a part of the upper surface of the substrate so as to close the opening, and a solid is formed. A cell structure in which an electrolyte layer is coated on the lower surface of the upper electrode layer from the whole or a part of the lower surface of the substrate via the opening, and the lower electrode layer is further laminated on the whole or a part of the lower surface of the solid electrolyte layer. Has been described.
[0006]
[Patent Document 1]
JP 2002-170578 A
[0007]
[Problems to be solved by the invention]
In Patent Document 1, in order to form an opening in a substrate, a method of anisotropically etching a silicon substrate (see FIGS. 5 to 7) and a method of machining (see FIGS. 9 to 12) are employed. .
However, in the method of forming an opening in a substrate in advance by machining, it is not only complicated to form a large number of openings, or the machining itself is difficult depending on the type of the substrate, and the opening is not limited. In order to stack the battery elements so as to straddle the battery element, it is necessary to form a temporary substrate or a temporary substrate layer prior to the formation of the battery element and to remove it after the film formation, which makes the process complicated. This is a cost increase factor.
[0008]
On the other hand, a method in which a single-crystal silicon substrate is used as a substrate, and after the formation of the battery element, the opening is formed by etching the substrate from the back side of the film-forming surface with an etchant to form many openings at once. Although it is advantageous in that it can be formed uniformly, in the case of isotropic etching, since the corrosion easily propagates in the direction of the substrate surface inside the mask layer, the substantial dimensions between the adjacent openings are obtained. And the mechanical strength of the substrate may be reduced.
[0009]
On the other hand, when anisotropic etching using a solution containing potassium hydroxide or hydrazine as a main component as an etchant is performed from the back surface side of the film formation surface, the substrate is set so that the (111) surface with the slowest etching rate remains. Dissolves, the opening angle α (see FIG. 1A) of the opening becomes an acute angle, that is, an opening that expands toward the back side of the film-forming surface of the battery element, so that the opening area with respect to the substrate is increased. In other words, there is a problem in that the power generation effective area of the battery is reduced, the power generation output is reduced, the output per unit volume is limited, and the miniaturization of the fuel cell is limited.
[0010]
The present invention has been made in view of the above-mentioned problems in a conventional solid oxide fuel cell, and has a solid oxide type in which a cell element including a solid oxide electrolyte and both electrodes sandwiching the solid oxide electrolyte is supported by a substrate. In a solid fuel cell, a cell for a solid oxide fuel cell that can increase the ratio of the opening area of the opening in the support substrate and can increase the power generation effective area to improve the power generation output. It is an object of the present invention to provide a cell plate for a solid oxide fuel cell in which various fuel cell cells are two-dimensionally arranged, and a method for producing the fuel cell and the cell plate.
[0011]
[Means for Solving the Problems]
The solid oxide fuel cell for use in the present invention has a structure in which a battery element in which an electrolyte layer made of a solid oxide is sandwiched between upper and lower electrode layers is laminated on a substrate and supported, and the substrate is A single crystal silicon substrate having a (100) plane as a surface, wherein a battery element is stacked so as to cover an opening formed in the substrate, and an opening angle of the substrate opening is 90 ° or more; The solid oxide fuel cell plate according to the present invention is characterized in that the solid oxide fuel cell cells are two-dimensionally connected and integrated in a direction substantially perpendicular to the stacking direction. It is characterized by having a configuration that
[0012]
Further, the method for producing a cell or cell plate for a solid oxide fuel cell of the present invention can be suitably applied to the production of the fuel cell or the cell plate, and is soluble in an etching solution on the upper surface of a silicon substrate. After forming the sacrificial layer, the lower surface side of the silicon substrate is removed by anisotropic etching, the sacrificial layer is removed by isotropic etching, and the upper surface side of the silicon substrate is further removed by anisotropic etching. In a preferred embodiment of the manufacturing method, after forming a sacrificial layer soluble in an anisotropic etchant as the sacrificial layer, from the lower surface side of the silicon substrate By performing the etching, the anisotropic etching of the lower surface of the substrate, the isotropic etching of the sacrificial layer, and the anisotropic etching of the upper surface of the substrate are continuously performed using one type of anisotropic etching solution. It is also possible.
[0013]
Further, a solid oxide fuel cell stack and a solid oxide fuel cell system of the present invention are characterized in that the solid oxide fuel cell stack or the solid oxide fuel cell cell plate according to the present invention is used. Features.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the cell and cell plate for a solid oxide fuel cell of the present invention will be described in detail together with the method for producing the same.
In addition, in this specification, "%" means a mass percentage unless otherwise specified. For convenience of description, one surface of each layer such as a substrate and an electrolyte layer is referred to as an “upper surface (or front surface)”, and the other surface is referred to as a “lower surface (or rear surface)”. ), But described as "lower electrode layer", but these are merely indicative of the relative positional relationship, the upper electrode layer is not necessarily located above the lower electrode layer in use, In some cases, the “top surface” may be used in a vertical state or an inclined state. Therefore, it goes without saying that a configuration in which these are mutually replaced is also included in the scope of the present invention.
[0014]
FIGS. 1A to 1F show examples of the cross-sectional shape of a solid oxide fuel cell according to the present invention. The solid oxide fuel cell according to the present invention has a structure of (100) An opening formed in the substrate 1 by a battery element in which an electrolyte layer 2 made of a solid oxide is sandwiched between upper and lower electrode layers 3 and 4 (fuel electrode and air electrode) in a single crystal silicon substrate 1 having a surface as a surface. 5, the opening angle α formed by the upper surface of the substrate 1 on which the battery elements 2, 3, and 4 are stacked and the wall surface of the opening 5 is 90 ° or an obtuse angle exceeding 90 °. Therefore, the cell plate for a solid oxide fuel cell of the present invention is obtained by arranging a large number of such cells two-dimensionally in the surface direction of the substrate 1 and connecting and integrating them. Therefore, as compared with the conventional fuel cell and cell plate in which the opening angle α is acute, Effective power generation area of the battery element without reducing the first intensity becomes wider, the power output per unit volume increase, corresponding to the miniaturization of the fuel cell becomes possible.
[0015]
In the solid oxide fuel cell and cell plate of the present invention, as described above, neodymium oxide (Nd ₂ O ₃ ), Samarium oxide (Sm ₂ O ₃ ), Yttria (Y ₂ O ₃ ), Gadolinium oxide (Gd ₂ O ₃ ), Scandium oxide (Sc ₂ O ₃ ) And ceria (CeO) ₂ ) -Based solid solution, bismuth oxide (BiO ₂ ) And lanthanum gallate (LaGaO) ₃ ) Can be used, but the material is not limited thereto.
[0016]
In addition, the air electrode, which is one of the upper and lower electrode layers, is required to be resistant to oxidation, permeate oxidizing gas, have high electric conductivity, and have excellent catalytic action for converting oxygen molecules into oxygen ions. Generally, for example, a metal-based material such as silver (Ag) or platinum (Pt), or an oxide material having a perovskite structure represented by LaSrMnO or LaSrCoO can be used.
[0017]
The fuel electrode, which is the other of the upper and lower electrode layers, is required to be strong in a reducing atmosphere, permeate a fuel gas, have high electric conductivity, and have an excellent catalytic action of converting hydrogen molecules into protons. For example, nickel (Ni) or a cermet of nickel and a solid electrolyte can be generally used.
[0018]
The solid oxide fuel cell and cell plate of the present invention are obtained by forming a sacrificial layer soluble in an etchant on the upper surface of a silicon substrate and then removing the lower surface of the silicon substrate by anisotropic etching. The sacrifice layer can be obtained by removing the sacrifice layer by isotropic etching and removing the upper surface side of the silicon substrate by anisotropic etching to form an opening.
[0019]
That is, a mixed solution of hydrofluoric acid and phosphoric acid (HF-H ₃ PO ₄ ) Or a mixed solution of hydrofluoric nitric acid or hydrofluoric nitric acid with water or acetic acid (aq-HF-HNO ₃ , HF-HNO ₃ -CH ₃ COOH) and an isotropic etchant whose etching rate is constant irrespective of the plane orientation of the silicon substrate, and hydrazine hydrate (aq-H ₂ NNH ₂ ), Potassium hydroxide (KOH), TMAH (methylammonium hydroxide), EDP (ethylenediamine-pyrocatechol) and the like, and anisotropic etchants whose etching rate largely depends on the plane orientation of silicon. When anisotropic etching is performed from the (100) plane, the etching stops at the (111) plane where the etching rate is the slowest. Therefore, when anisotropic etching is performed from the back surface side on which the battery elements are stacked, an opening having a cross-sectional shape that expands toward the back surface side is formed. After reaching the sacrificial layer formed on the (side), the sacrificial layer is removed by isotropic etching, and further anisotropic etching is performed, whereby the front surface side of the substrate is etched and eventually etched on the (111) plane. Stops, the aperture angle α becomes 90 ° or more as shown in FIG.
[0020]
At this time, depending on the thickness of the silicon substrate 1, the size of the sacrificial layer formed on the upper surface side (front surface side), the opening width of the back side mask layer, and the like, the cross-sectional shape of the opening 5 is shown in FIGS. V-type pattern as in b), X-type as in (c) and (d), and U-type pattern with opening angle α of 90 ° as in (e) and (f) by increasing the thickness of the sacrificial layer. It becomes.
In FIG. 1, reference numeral 6 denotes an insulating layer that also functions as a stress relieving layer, for example, silicon oxide (SiO 2). ₂ ), Silicon nitride (Si ₃ N ₄ ), PSG (phosphosilicate glass), PBSG (phosphoborosilicate glass), alumina (Al ₂ O ₃ ), Titania (TiO ₂ ), Zirconia (ZrO) ₂ ), Magnesia (MgO) or the like can be used. Although FIG. 1 shows the case where the battery element is formed on the upper surface side of the substrate 1, one or two of the battery elements may be formed on the back surface (lower surface) side.
[0021]
The solid oxide fuel cell and cell plate of the present invention, specifically, for example,
[1]: forming a sacrificial layer on a predetermined portion of the upper surface of the silicon substrate,
[2]: forming an insulating layer on the upper surface of the substrate and forming a mask layer for forming an opening on the lower surface;
[3]: forming a lower electrode layer in contact with the insulating layer,
[4]: forming an electrolyte layer in contact with the lower electrode layer,
[5]: forming an upper electrode layer in contact with the electrolyte layer,
[6]: a step of anisotropically etching the lower surface side of the substrate,
[7]: a step of isotropically etching the sacrificial layer formed on the substrate,
[8]: a step of anisotropically etching the upper surface side of the substrate,
[9]: removing the insulating layer formed on the lower surface of the lower electrode layer,
[10]: removing a mask layer formed on the lower surface of the substrate,
Can be manufactured by a manufacturing process including:
According to this step, the lower electrode 4, the electrolyte 2, and the upper electrode 3 can be continuously formed on one side of the base material 1, and the positive and negative electrodes are collected from one side.
[0022]
In the above steps, either of the steps [1] and [2] may be performed first, and the step [6] is performed after the steps [1] and [2], that is, the sacrificial layer, the insulating layer, and the mask layer. After the formation of the lower electrode 4, it may be basically performed at any time. However, in consideration of the strength of the insulating layer, it is preferable to perform at least after the formation of the lower electrode 4. Steps [7] to [9] may be performed in this order after step [6], and steps [4] and [5] may be inserted between them. After forming the elements continuously (steps [3] to [5]), it is rational and advantageous for the steps to continuously perform the etching in steps [6] to [8]. . Either of the steps [9] and [10] may be performed first.
[0023]
Note that, in each of the above film forming steps, generally, a sputtering method, an electron beam evaporation method, a plasma spray method, an ion plating method, a frame spray method, a plasma jet torch method, an EVD method, a CVD method, or the like can be applied. it can.
[0024]
In addition, the following manufacturing process, namely,
[1]: forming a sacrificial layer on a predetermined portion of the upper surface of the silicon substrate,
[2]: forming an insulating layer on the upper surface of the substrate and forming a mask layer for forming an opening on the lower surface;
[3]: a step of anisotropically etching the lower surface side of the substrate,
[4]: a step of isotropically etching the sacrificial layer formed on the substrate,
[5]: a step of anisotropically etching the upper surface side of the substrate,
[6]: forming an electrolyte layer in contact with the insulating layer,
[7]: a step of removing the insulating layer formed on the lower surface of the electrolyte layer,
[8]: forming an upper electrode layer in contact with the electrolyte layer,
[9]: forming a lower electrode layer in contact with the electrolyte layer from the lower surface side of the substrate,
[10]: removing a mask layer formed on the lower surface of the substrate,
By forming the upper electrode layer 3 and the electrolyte layer 2 on the upper surface side of the substrate 1 and the lower electrode layer 4 on the lower surface side, the current collection of the air electrode and the fuel electrode is performed on the surface of the substrate 1. It can be divided into a side and a back side, and the patterning of current collection is simplified, so that the effective area of the cell can be further increased and the output can be further improved.
[0025]
In the above steps, the step [1] and the step [2], that is, the formation of the sacrificial layer and the insulating layer may be performed first, and the step [6] is performed after the formation of the sacrificial layer, the insulating layer and the mask layer. Then, the etching may be basically performed after the opening is etched. However, in consideration of the strength of the insulating layer, it is preferable that the etching be performed before the opening is formed by etching. The step [8] may be performed any time after the formation of the electrolyte layer, and the step [9] may be performed before or after the formation of the upper electrode layer as long as the insulating layer in contact with the electrolyte layer is removed. Step [10] may be performed any time after the end of the etching (step [5]).
[0026]
In addition, the following manufacturing process, namely,
[1]: forming a sacrificial layer on a predetermined portion of the upper surface of the silicon substrate,
[2]: forming an insulating layer on the upper surface of the substrate and forming a mask layer for forming an opening on the lower surface;
[3]: a step of anisotropically etching the lower surface side of the substrate,
[4]: a step of isotropically etching the sacrificial layer formed on the substrate,
[5]: a step of anisotropically etching the upper surface side of the substrate,
[6]: forming an upper electrode layer in contact with the insulating layer,
[7]: removing an insulating layer formed on the lower surface of the upper electrode layer,
[8]: forming an electrolyte layer in contact with the upper electrode layer from the lower surface side of the substrate,
[9]: forming a lower electrode layer in contact with the electrolyte layer,
[10]: removing a mask layer formed on the lower surface of the substrate,
By forming the upper electrode layer 3 on the upper surface side of the substrate 1 and the electrolyte layer 2 and the lower electrode layer 4 on the lower surface side by adopting the manufacturing process including The current collection of the fuel electrode can be divided into the front surface side and the back surface side of the substrate 1, and the current collection can be easily patterned. And, by simplification of the patterning, the effective area of the cell is further increased, and the output can be further improved.
[0027]
In the above step, either the step [1] or the step [2], that is, the formation of the sacrificial layer and the insulating layer may be performed first, and in the step [6], the sacrificial layer, the insulating layer and the mask layer are similarly formed. After the formation of the opening, it may be basically before or after the etching of the opening. Steps [7] to [9] are performed in this order after forming the upper electrode layer and after removing the insulating layer in contact with the upper electrode layer. The step [10] may be performed any time after the end of the etching (step [5]).
[0028]
In each of the above-described manufacturing methods, the insulating layer formed in step [2] may be the same as the mask layer, that is, an insulating layer that can withstand an etchant and also functions as a mask layer. Thereby, these film formation and removal can be performed simultaneously or continuously, and the process can be simplified.
[0029]
In each of the above-described manufacturing methods, as the sacrificial layer, a metal or oxide is formed on a silicon substrate, ⁺ , Ge ⁺ , Ne ⁺ , H ⁺ , B ⁺ , O ⁺ Such ions can be formed by injecting ions of a high concentration into a silicon substrate to alter the quality. Table 1 shows examples of metals and oxides that can be formed as the sacrificial layer together with their etching solutions. In Table 1, phosphoric acid (H ₃ PO ₄ ) Or the etching solution containing hydrofluoric acid (HF) is Si ₃ N ₄ And the etching solution of hydrofluoric acid (HF) alone is Si ₃ N ₄ And SiO ₂ Therefore, when using these etchants, it is necessary to consider the material of the mask layer.
[0030]
[Table 1]

[0031]
In forming the sacrificial layer, it is preferable to form a silicon oxide or silicon nitride layer into a sacrificial layer that is soluble in an anisotropic etching solution such as hydrazine by film formation or ion implantation. Side anisotropic etching, the isotropic etching of the sacrificial layer, and the anisotropic etching of the upper surface of the base material can be continuously performed by using one type of anisotropic etching solution. Simplification can be achieved.
[0032]
Further, in the manufacturing method of the present invention, at the time of etching, it is preferable that the battery elements formed on the substrate at that time are masked by, for example, PSG (phosphosilicate glass) or the like. The lamination interface is not exposed to the etching solution, and the reaction resistance of the electrode layer is reduced, so that the output can be improved.
[0033]
A fuel cell stack can be formed using the solid oxide fuel cell or the solid oxide fuel cell plate of the present invention, thereby increasing the effective power generation area and the number of cells. As a result, the power generation output will increase.
Further, the above-described cell for a solid oxide fuel cell or the cell plate for a solid oxide fuel cell according to the present invention can be applied to a fuel cell system. For example, the supply amounts of fuel gas and oxidant gas (air) The power generation efficiency of the entire system can be further improved by incorporating the control section and the gas supply section together with the control section for controlling the gas supply amount to an optimum state.
[0034]
【Example】
Hereinafter, the present invention will be specifically described based on examples. Note that the present invention is not limited to only these examples.
[0035]
(Example 1)
As the substrate 1, a single-crystal silicon substrate having a (100) plane as a surface and a thickness of 0.5 mm is used. First, as shown in FIG. A resist 11 was applied. Then, patterning was performed by photolithography to form a square ion implantation port 11a for forming a sacrifice layer having a side of 2 mm as shown in FIG. 2B.
[0036]
Next, as shown in FIG. 2C, a high concentration of Ar ions is injected from the injection port 11a with an acceleration voltage of 75 keV and an injection amount of 1 × 10 3. ^Fifteen / Cm ² Then, the portion is made non-crystalline to form a sacrificial layer 12 on the surface of the substrate 1, and then, as shown in FIG. 2D, an organic solvent or an appropriate etching solution is used to form a resist 11. Was removed.
Further, as shown in FIG. 2E, Si is formed on the upper and lower surfaces of the silicon substrate 1 by CVD. ₃ N ₄ An insulating layer 6 composed of a layer was formed. Note that the Si ₃ N ₄ The layer also functions as a mask layer during etching when forming the opening, and is formed on the lower surface side of the substrate 1. ₃ N ₄ With respect to the layer 6, an etching opening 13 for forming a square opening having a side of 3 mm is formed. The sacrifice layer 12 was formed using Si ₃ N ₄ After the layer 6 is formed, masking and ion implantation can also be performed. In this case, Si having a large tensile stress is applied to the Si single crystal substrate. ₃ N ₄ Since the bond between the layers is broken by ion implantation and the tensile stress is reduced, an effect of improving the strength of the electrolyte layer formed in the opening can also be expected.
[0037]
Then, the Si film formed on the upper surface side of the substrate 1 ₃ N ₄ On the layer 6, as shown in FIG. 2 (f), the LSC (La _0.8 Sr _0.2 CoO ₃ ) Was formed to a thickness of 0.5 μm by RF sputtering at 200 W in 10 Pa of Ar to form a lower electrode layer 4, and 8YSZ (8 mol% Y) was formed on the air electrode 4. ₂ O ₃ ZrO added ₂ 2) was formed to a thickness of 2 μm by RF sputtering at 200 W in 1 Pa of Ar to form an electrolyte layer 2 as shown in FIG.
Further, FIG. 2 (h) shows an RF sputtering method (200 W, 1 Pa (Ar)) using a target obtained by mixing NiO and 8YSZ raw material powder at a ratio of 1: 1 and firing on the electrolyte layer 2. As described above, the NiO-8YSZ cermet as the fuel electrode was formed to a thickness of 0.5 μm to form the upper electrode layer 3.
[0038]
Next, as shown in FIG. ₃ N ₄ A mask material 14 made of PSG (phosphosilicate glass) is formed on the layer 6 by CVD, ₃ N ₄ After masking so as to cover the battery elements 2, 3 and 4 formed on the layer 6, as shown in FIG. 3 (j), a hydrazine-based etching solution is applied from the back (lower) side of the substrate 1. Is used to anisotropically etch the lower surface of the silicon substrate 1 until it reaches the previously formed sacrificial layer 12, and then, as shown in FIG. Removed by reactive etching. Then, the upper surface side of the silicon substrate 1 was anisotropically etched with the same etching solution. As a result, the etching stops at the (111) plane of the silicon material, and an opening 5 having an obtuse opening angle α is formed as shown in FIG.
[0039]
Next, as shown in FIG. ₄ Plasma etching is performed using Si and the lower surface of the air electrode 4 is in contact with Si. ₃ N ₄ Si adhered to the layer portion and the periphery of the opening 5 on the lower surface of the substrate 1 ₃ N ₄ After removing the layer, finally HF-HNO ₃ By removing the mask material 14 with an etchant, a solid oxide fuel cell can be obtained.
[0040]
According to the manufacturing method according to this embodiment, the battery elements 4, 2, and 3 can be formed continuously, and the opening 5 having an obtuse opening angle α is etched by the same anisotropic etching solution. It can be performed continuously, and the process can be simplified. Further, since the battery element formed prior to the etching of the opening 5 is masked, the laminated interface of the battery element is not affected by the etching solution, and the reaction resistance of the electrode layer is reduced. The power generation output can be improved.
[0041]
(Example 2)
Next, as a second embodiment of the present invention, a method for forming a battery element from both upper and lower surfaces of the substrate 1 will be described.
First, as shown in FIGS. 4A to 4E, a sacrifice layer is formed by using a single-crystal silicon substrate having a thickness of 0.5 mm and having a (100) plane as a surface, as shown in FIGS. 12 and the insulating layer 6 were formed.
[0042]
Next, as shown in FIG. 4F, the insulating layer 6 formed on the upper surface side of the substrate 1 ₃ N ₄ A solid electrolyte made of 8YSZ was formed on the layer by the same RF sputtering method as in Example 1 to form an electrolyte layer 2.
[0043]
Then, as shown in FIG. 4 (g), the lower surface side of the silicon substrate 1 is anisotropically etched from the back surface (lower surface) side of the substrate 1 using a hydrazine-based etchant. 5), the sacrificial layer 12 is removed by isotropic etching with the above-mentioned etching solution, and the upper surface side of the silicon substrate 1 is further anisotropically etched with the same etching solution, as shown in FIG. An opening 5 similar to that of Example 1 was formed.
[0044]
Next, as shown in FIG. ₄ By plasma etching using Si, Si on the lower surface of the electrolyte layer 2 ₃ N ₄ Si adhered to the layer portion and the periphery of the opening 5 on the lower surface of the substrate 1 ₃ N ₄ After removing the layer, as shown in FIG. 5 (k), an LSC as an air electrode is formed on the electrolyte layer 2 by a similar RF sputtering method (200 W, 10 Pa (Ar)) to form an upper electrode layer 3. And
Finally, from the lower surface side of the substrate 1, NiO-8YSZ cermet as a fuel electrode is formed on the lower surface of the electrolyte layer 2 by the revolving oblique sputtering by the RF sputtering method to form a lower electrode layer 4, and FIG. ), A cell for a solid oxide fuel cell was completed.
[0045]
According to the manufacturing method according to this embodiment, similarly to the above-described embodiment, the etching of the opening 5 having the obtuse opening angle α can be continuously performed using the same anisotropic etching solution, and the air electrode In addition, the current collection of the fuel electrode can be divided into the front surface side and the back surface side of the substrate 1, so that the patterning of the current collection is simplified, the effective area of the cell is further increased, and the output can be further improved.
[0046]
(Example 3)
Also in the third embodiment of the present invention, a method of forming a battery element from both the upper and lower surfaces of the substrate 1 will be described as in the second embodiment.
Similarly, as shown in FIGS. 6A to 6F, a single crystal silicon substrate having a thickness of 0.5 mm and having the (100) plane as the surface is used, and the sacrificial layer is formed in the same procedure as in the second embodiment. 12 and the insulating layer 6 were formed, and a solid electrolyte made of 8YSZ was formed on the insulating layer by a similar RF sputtering method to form an electrolyte layer 2.
[0047]
Next, as shown in FIG. 6G, an LSC as an air electrode is formed on the electrolyte layer 2 by a similar RF sputtering method to form an upper electrode layer 3, and then, as shown in FIG. As shown, the Si film formed on the upper surface side of the substrate 1 ₃ N ₄ A mask material 14 made of PSG is formed on the layer 6 by CVD, ₃ N ₄ Masking was performed so as to cover the electrolyte layer 2 and the air electrode 3 formed on the layer 6.
[0048]
After masking the battery element with PSG, as shown in FIGS. 7 (i) to 7 (k), an opening 5 is formed by the same etching as in the above embodiment, and as shown in FIG. Si on the back side of the electrolyte layer 2 and the bottom side of the substrate 1 ₃ N ₄ After removing the layer 6 in the same manner, as shown in FIG. ₃ The mask material 14 was removed with an etching solution containing as a main component.
Then, from the lower surface side of the substrate 1, NiO-8YSZ cermet as a fuel electrode is formed on the lower surface of the electrolyte layer 2 by the revolving oblique sputtering by the RF sputtering method to form a lower electrode layer 4, and FIG. As shown, a solid oxide fuel cell was completed.
[0049]
According to the manufacturing method according to this embodiment, similarly to the above-described embodiment, the etching of the openings 5 having the obtuse opening angle α can be continuously performed with the same anisotropic etching solution, and the current collection can be performed. Is divided into the front side and the back side of the substrate 1 so that the patterning of current collection can be simplified, the output can be further improved by increasing the effective area of the cell, Since the element is masked, the lamination interface of the air electrode is not exposed to the etchant, the reaction resistance is reduced, and the power generation output can be improved.
[0050]
(Example 4)
As a fourth embodiment of the present invention, a case where the sacrificial layer 6 of the substrate 1 is formed will be described.
First, a single crystal silicon substrate having a thickness of 0.5 mm and having a (100) plane as a surface is used as the substrate 1, and a resist 11 is applied to the surface of the silicon substrate 1 as shown in FIG. Then, by performing patterning by photolithography, as shown in FIG. 8B, an opening 11b for forming a sacrificial layer was formed.
[0051]
Next, as shown in FIG. 8 (c), an Al layer is formed to a thickness of 0.5 μm inside and around the opening 11b of the resist 11 by DC sputtering with an output of 300 W in Ar of 1 Pa. After the film was formed to form the sacrificial layer 12, the resist 11 was removed using an organic solvent or an etchant, leaving only the sacrificial layer 12 on the substrate 1, as shown in FIG. At this time, the level of the sacrificial layer 12 can be made the same as that of the substrate 1 by polishing the surface after forming the Al film in a state where the surface of the silicon substrate 1 is shaved to form the depressions. In the process, the insulating layer 6 can be formed flat.
[0052]
Next, as shown in FIG. 8E, Si is formed on the upper and lower surfaces of the silicon substrate 1 by CVD. ₃ N ₄ The insulating layer 6 composed of a layer was formed, and an etching port 13 for forming an opening was formed on the lower surface side of the substrate 1. Next, as shown in FIG. 8F, the Si film formed on the upper surface side of the substrate 1 is formed. ₃ N ₄ A solid electrolyte made of 8YSZ was similarly formed on the layer 6 by RF sputtering in the same manner as in Examples 2 and 3 to form an electrolyte layer 2.
[0053]
Then, as shown in FIG. 8G, a hole reaching the sacrificial layer 12 is formed by anisotropically etching the lower surface side of the silicon substrate 1 from the lower surface side of the substrate 1 using a hydrazine-based etchant. After that, isotropic etching of the sacrificial layer 12 was performed using hydrochloric acid, and the sacrificial layer 12 was removed as shown in FIG. Further, the upper surface side of the silicon substrate 1 was anisotropically etched with a hydrazine-based etchant to form openings 5 similar to those in Examples 2 and 3, as shown in FIG.
[0054]
Next, as shown in FIG. 9J, the lower surface of the substrate 1 is subjected to plasma etching using CF 4 by plasma etching, and the Si adhered to the lower surface of the electrolyte layer 2 and the lower surface of the substrate 1. ₃ N ₄ After removing the layer 6, as shown in FIG. 9 (k), an LSC as an air electrode is formed on the electrolyte layer 2 by a similar RF sputtering method (200 W, 10 Pa (Ar)) to form an upper electrode layer. It was set to 3.
Finally, from the lower surface side of the substrate 1, NiO-8YSZ cermet as a fuel electrode is formed on the lower surface of the electrolyte layer 2 by revolving oblique sputtering by RF sputtering to form a lower electrode layer 4, and FIG. The cell for a solid oxide fuel cell as shown in (1) was obtained.
[0055]
(Example 5)
A fuel cell comprising a conventional type of cell plate having an acute opening angle α is fabricated by manufacturing a cell plate in which a plurality of cells having the structure shown in Example 2 are arranged, stacking the cell plates, and assembling the fuel cell stack. And performance comparison.
[0056]
That is, a single-crystal silicon substrate 1 of 100 mm × 100 mm × 0.5 mm having a (100) plane as a surface is used, and this substrate 1 has the same structure as that of Example 2 as shown in FIG. Single cells having a size, that is, an effective stacking size of the battery element of 2 mm square were two-dimensionally arranged. Assuming that a sealing margin is 5 mm from each edge of the cell plate and the distance between cells on the back surface side of the substrate 1 is at least 0.5 mm, the cell structure of Example 2 in which the opening angle α of the opening 5 is obtuse is By adopting this, the inter-cell distance on the front surface side of the substrate 1 can be made 1 mm, and a total of 900 single cells can be arranged along one side of the substrate 1.
[0057]
As shown in FIG. 11, a fuel cell stack is manufactured by stacking 100 such cell plates with a separator having a plate thickness of 0.5 mm and a groove depth of 0.2 mm each interposed therebetween as shown in FIG. The height became 100.5 mm.
In such a fuel cell, the power density is 0.2 W / cm. ² Therefore, an output of 7.2 W (0.2 × 0.2 × 900 × 0.2) per cell plate and 720 W is obtained for the entire stack.
[0058]
On the other hand, without forming a sacrificial layer, ₃ N ₄ After forming an insulating layer made of YSZ and forming an electrolyte layer made of 8YSZ, an opening is formed by anisotropic etching, and then an air electrode made of LSC and a fuel electrode made of NiO-8YSZ cermet are sequentially formed. In the conventional cell structure manufactured as described above, since the opening angle α of the opening is an acute angle, if the sealing margin is 5 mm, as shown in FIG. Also, the distance between cells on the substrate surface side was 3.21 mm, and only 17 rows of single cells could be arranged (total of 289 cells). Therefore, the output per cell plate was 2.31 W (0%). .2 × 0.2 × 289 × 0.2), and only 231 W of output can be obtained with the entire stack.
[0059]
(Example 6)
FIG. 12 is a block diagram illustrating a configuration example of a solid oxide fuel cell system according to the present invention. The fuel cell system includes a fuel cell stack using the fuel cell or the cell plate according to the present invention; A fuel supply unit for supplying fuel gas such as hydrogen or hydrocarbon to the fuel cell stack, an air supply unit for supplying air to the fuel cell stack, and various sensors connected to the fuel cell stack, the fuel supply unit, and the air supply unit. It is mainly composed of a control device connected to the controller.
[0060]
In the above-described system, the control device most efficiently adjusts the temperature, the fuel supply amount, and the air supply amount according to the temperature of the fuel cell stack detected by each sensor, the supply gas component, the exhaust gas component, the battery output, and the like. Since the power generation is controlled to be performed, the power generation efficiency of the entire system can be further improved together with the improvement of the power generation output per unit volume of the fuel cell stack.
[0061]
【The invention's effect】
As described above, according to the present invention, a cell for a solid oxide fuel cell having a structure in which battery elements are stacked so as to close an opening formed in a single crystal silicon substrate having a (100) plane as a surface. Or, in the cell plate, since the opening angle α between the substrate surface and the wall surface of the opening is 90 ° or more, the opening angle α is smaller than that of the conventional fuel cell and cell plate in which the opening angle α is acute. The effective power generation area of the battery element can be increased without reducing the strength of the fuel cell, the power generation output per unit volume can be greatly improved, and the fuel cell can be downsized. .
Further, according to the manufacturing method of the present invention, after forming a sacrificial layer on the stack side of the battery element of the silicon substrate, the substrate is anisotropically etched from the anti-stack side, and the sacrificial layer is isotropically etched. Then, by performing anisotropic etching on the laminated surface side of the substrate, an opening having an opening angle α of 90 ° or more can be formed.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a sectional shape of an opening in a cell for a solid oxide fuel cell of the present invention.
FIG. 2 is a process chart showing a first half of a manufacturing procedure of a cell for a solid oxide fuel cell according to a first embodiment of the present invention.
FIG. 3 is a process chart showing the latter half of the manufacturing procedure of the cell for a solid oxide fuel cell according to the first embodiment of the present invention.
FIG. 4 is a process chart showing a first half of a manufacturing procedure of a cell for a solid oxide fuel cell according to a second embodiment of the present invention.
FIG. 5 is a process chart showing the latter half of the procedure for manufacturing the solid oxide fuel cell according to the second embodiment of the present invention.
FIG. 6 is a process chart showing a first half of a manufacturing procedure of a cell for a solid oxide fuel cell according to a third embodiment of the present invention.
FIG. 7 is a process chart showing the latter half of the procedure for manufacturing the solid oxide fuel cell according to the third embodiment of the present invention.
FIG. 8 is a process chart showing a first half of a manufacturing procedure of a cell for a solid oxide fuel cell according to a fourth embodiment of the present invention.
FIG. 9 is a process chart showing the latter half of the procedure for manufacturing the solid oxide fuel cell according to the fourth embodiment of the present invention.
FIG. 10 is a perspective view and a sectional view showing the shape of the solid oxide fuel cell plate of the present invention.
FIG. 11 (a) is a cross-sectional view showing a shape of a solid oxide fuel cell stack of the present invention.
(B) It is a perspective view showing the shape of the separator shown in Drawing 11 (a).
FIG. 12C is a perspective view of the stack shown in FIG.
FIG. 12 is a block diagram showing a configuration example of a solid oxide fuel cell system of the present invention.
FIG. 13 is a perspective view and a sectional view showing the shape of a conventional solid oxide fuel cell plate.
[Explanation of symbols]
1 Silicon substrate
2 Electrolyte layer
3 Upper electrode layer
4 Lower electrode layer
5 opening
6 Insulation layer
12 Sacrificial layer
14 Masking

Claims (12)

In a solid oxide fuel cell, a battery element in which an electrolyte layer composed of a solid oxide is sandwiched between an upper electrode layer and a lower electrode layer is laminated on a substrate,
The substrate is a single crystal silicon substrate having a (100) plane as a surface, the battery element is stacked so as to cover an opening formed in the substrate, and the opening angle of the substrate opening is 90%. ° or more, a cell for a solid oxide fuel cell. A cell plate for a solid oxide fuel cell, wherein a plurality of the fuel cell cells according to claim 1 are two-dimensionally connected and integrated in a direction substantially orthogonal to the stacking direction. A method for producing the fuel cell according to claim 1 or the fuel cell plate according to claim 2,
After forming a sacrificial layer soluble in an etching solution on the upper surface of the silicon substrate, the lower surface side of the silicon substrate is removed by anisotropic etching, and then the sacrificial layer is removed by isotropic etching. A method for manufacturing a cell or cell plate for a solid oxide fuel cell, comprising a step of forming an opening by removing an upper surface side of a substrate by anisotropic etching. [1]: forming a sacrificial layer on a predetermined portion of the upper surface of the silicon substrate,
[2]: a step performed after or before the step [1], wherein an insulating layer is formed on the upper surface of the substrate and a mask layer for forming an opening is formed on the lower surface;
[3]: forming a lower electrode layer in contact with the insulating layer,
[4]: forming an electrolyte layer in contact with the lower electrode layer,
[5]: forming an upper electrode layer in contact with the electrolyte layer,
[6]: a step performed after the step [1] and the step [2], wherein the lower surface side of the substrate is anisotropically etched;
[7]: a step which is performed after the step [6] and isotropically etches the sacrificial layer formed on the substrate,
[8]: a step performed after the step [7], wherein the upper surface side of the substrate is anisotropically etched;
[9]: a step which is performed after the step [8] and removes the insulating layer formed on the lower surface of the lower electrode layer;
[10]: a step which is performed after the step [8] and removes the mask layer formed on the lower surface of the substrate.
The method for producing a cell or cell plate for a solid oxide fuel cell according to claim 3, comprising: [1]: forming a sacrificial layer on a predetermined portion of the upper surface of the silicon substrate,
[2]: a step performed after or before the step [1], wherein an insulating layer is formed on the upper surface of the substrate and a mask layer for forming an opening is formed on the lower surface;
[3]: a step of anisotropically etching the lower surface side of the substrate,
[4]: a step of isotropically etching the sacrificial layer formed on the substrate,
[5]: a step of anisotropically etching the upper surface side of the substrate,
[6]: a step performed after step [1] and step [2] to form an electrolyte layer in contact with the insulating layer,
[7]: a step which is performed after the steps [5] and [6] and removes the insulating layer formed on the lower surface of the electrolyte layer;
[8]: a step performed after step [6] to form an upper electrode layer in contact with the electrolyte layer;
[9]: a step which is performed after the step [7] and forms a lower electrode layer in contact with the electrolyte layer from the lower surface side of the substrate,
[10]: a step performed after step [5], wherein the mask layer formed on the lower surface of the substrate is removed;
The method for producing a cell or cell plate for a solid oxide fuel cell according to claim 3, comprising: [1]: forming a sacrificial layer on a predetermined portion of the upper surface of the silicon substrate,
[2]: a step performed after or before the step [1], wherein an insulating layer is formed on the upper surface of the substrate and a mask layer for forming an opening is formed on the lower surface;
[3]: a step of anisotropically etching the lower surface side of the substrate,
[4]: a step of isotropically etching the sacrificial layer formed on the substrate,
[5]: a step of anisotropically etching the upper surface side of the substrate,
[6]: a step performed after step [1] and step [2] to form an upper electrode layer in contact with the insulating layer;
[7]: a step which is performed after the steps [5] and [6] and removes the insulating layer formed on the lower surface of the upper electrode layer;
[8]: a step which is performed after the step [7] and forms an electrolyte layer in contact with the upper electrode layer from the lower surface side of the substrate,
[9]: a step performed after step [8] to form a lower electrode layer in contact with the electrolyte layer;
[10]: a step performed after step [5], wherein the mask layer formed on the lower surface of the substrate is removed;
The method for producing a cell or cell plate for a solid oxide fuel cell according to claim 3, comprising: 7. The production of a cell or cell plate for a solid oxide fuel cell according to claim 3, wherein the insulating layer formed in step [2] is the same as the mask layer. Method. After forming a sacrificial layer composed of an amorphous layer or a polycrystalline layer soluble in an anisotropic etching solution on the upper surface of a silicon substrate, etching from the lower surface side of the substrate using the same type of anisotropic etching solution The method for producing a cell or cell plate for a solid oxide fuel cell according to any one of claims 3 to 7, wherein: The method for manufacturing a cell or cell plate for a solid oxide fuel cell according to claim 8, wherein a sacrificial layer is formed by implanting foreign ions into the upper surface of the silicon substrate. The cell or cell for a solid oxide fuel cell according to any one of claims 3 to 9, wherein at the time of etching, the battery element formed by masking the upper surface side of the substrate is protected. Board manufacturing method. A solid oxide fuel cell stack comprising the fuel cell according to claim 1 or the fuel cell plate according to claim 2. A solid oxide fuel cell system comprising the fuel cell according to claim 1 or the fuel cell plate according to claim 2.

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