JP4338060B2

JP4338060B2 - Manufacturing method of magnetic sensor

Info

Publication number: JP4338060B2
Application number: JP14844199A
Authority: JP
Inventors: 智幸林; 保敏鈴木; 勝定行; 廣文中野
Original assignee: FDK Corp
Current assignee: FDK Corp
Priority date: 1999-05-27
Filing date: 1999-05-27
Publication date: 2009-09-30
Anticipated expiration: 2019-05-27
Also published as: JP2000338211A

Description

【０００１】
【発明の属する技術分野】
本発明は、４個のスピンバルブ型磁気抵抗素子を単一基板上で菱形の頂点に位置するように配列形成し、それらを導電体層でループ状に接続した構造の磁気センサの製造方法に関するものである。この磁気センサは、例えば地磁気の検出や微小位置決めセンサなどに有用である。
【０００２】
【従来の技術】
微小な磁界を検知する超高感度磁気センサとして、ＮｉＦｅ，ＣｏＦｅ膜の異方性磁気抵抗効果（ＡＭＲ）を利用するものがある。この種の磁気センサは、フォトリソグラフィー技術によって基板上に多数個形成するように、蒸着法あるいはスパッタ法などにより作製される。これらの磁性膜は、温度変化に敏感であるため、ブリッジを組んで差動出力をとるように構成する。
【０００３】
軟磁性膜の異方性の制御方法としては、素子パターンの形状異方性を利用する方法と、永久磁石による磁界やコイルへの通電による磁界を印加しながら成膜して誘導磁気異方性を付与する方法がある。異方性磁気抵抗効果（ＡＭＲ）を利用する磁気抵抗素子においては、膜の磁化方向と電流の流れる向きとの相対角度で抵抗が変化するため、零磁界から正負の磁界に対して抵抗は対称に変化する。磁界センサとしては、ブリッジ回路で差動出力を得るように結線するため、磁気抵抗素子にバイアス磁界を加え、磁界に対する応答を線形にしている。
【０００４】
異方性磁気抵抗効果（ＡＭＲ）は、抵抗変化率（＝（抵抗変化量／抵抗値）×１００％）が２〜３％と低く、そこで、より高感度化の要求に対応するためＧＭＲ（巨大磁気抵抗効果）を利用したスピンバルブ型ＧＭＲ素子やスピントンネル現象を利用したスピンバルブ型トンネルＭＲ素子を用いる磁気センサが提案されている。
【０００５】
スピンバルブ型ＧＭＲ素子は、外部磁界に対し磁化の向きを自由に変えるフリー磁性層と、非磁性金属層と、外部磁界に対し応答し難いピン止め磁性層を積層した構造を有しており、２つの磁性層の磁化の向きの相対角度に依存して電気抵抗が変化する現象を利用している。このようなスピンバルブ型ＧＭＲ素子は、磁界に対する線形性が優れ、且つ抵抗変化率が５〜１０％と高い特性をもつ。
【０００６】
スピンバルブ型トンネルＭＲ素子は、外部磁界に対し磁化の向きを自由に変えるフリー磁性層と、絶縁層と、外部磁界に対し応答し難いピン止め磁性層を積層した構造を有しており、２つの磁性層間に電圧を印加し、電子をトンネリングさせたときの２つの磁性層の磁化の向きの相対角度により、電子のトンネル確率が変化する現象を利用している。外部磁界に対する抵抗変化率の変化を大きくするため、強磁性層に隣接して反強磁性層（ＦｅＭｎ，ＮｉＭｎ）を積層する構成が提案されている（特開平９−１０６５１４号公報参照）。また、ＮｉＦｅ／Ｃｏ／絶縁層（Ａｌ−Ａｌ₂Ｏ₃）／Ｃｏ／ＮｉＦｅ／ＦｅＭｎの積層構造において抵抗変化率が１０％以上得られることが報告されている（「磁化固定層をもつ強磁性トンネル接合の磁気抵抗効果」佐藤重雄、小林和雄、日本応用磁気学会誌 21,489-492(1997)参照）。
【０００７】
これらのスピンバルブ型磁気抵抗素子においては、ピン止め磁性層の磁化方向で磁界に対する線形動作方向を変化させることができる。このピン止め磁性層は反強磁性材料（ＦｅＭｎ，ＮｉＭｎ，ＩｒＭｎ，ＰｄＰｔＭｎ等）を隣接して積層することで磁化方向を固定する。
【０００８】
【発明が解決しようとする課題】
４個のスピンバルブ型磁気抵抗素子でブリッジを組み、磁界に対して差動出力を得るには、磁界に対して応答しにくいピン止め磁性層の磁化の向きを隣り合う素子同士で１８０度変えなければならない。ピン止め磁性層の磁化方向は、その上に成膜する反強磁性膜で決定される。その磁化方向は、成膜中の基板表面上に印加する磁界の向きによって規定されるし、反強磁性膜のネール温度付近からの磁界中熱処理における磁界方向によって規定される。
【０００９】
成膜時や熱処理中の磁界は永久磁石や電磁石によって与えられ、基板上には一方向の均一磁界が印加される。そのためピン止め磁性層の磁化の向きを１８０度変えたスピンバルブ型磁気抵抗素子を同一基板上に混在させることができない。そこで、ブリッジを組んだ磁気センサは、通常、個々のスピンバルブ型磁気抵抗素子を基板から取り出しリード線などで配線することで組み立てることになる。そうすると、配線などの工程が増え、小型化の妨げになるし、パッケージングの面でも難しくなる。
【００１０】
このような問題を解決する技術として、同一基板上でブリッジを組んだ磁気センサ上に、絶縁体層を介して導電体層を形成し、この導電体層に通電して磁界を発生させることによりピン止め磁性層の磁化の向きを１８０度変える方法が提案されている（特開平８−２２６９６０号公報参照）。しかし、この方法は、構成が複雑になる問題がある。
【００１１】
本発明の目的は、４個のスピンバルブ型磁気抵抗素子を同一基板上に配列形成してブリッジを組んだ磁気センサの製造方法を提供することである。
【００１２】
【課題を解決するための手段】
本発明は、４個のスピンバルブ型磁気抵抗素子が単一基板上で菱形の頂点位置に配列形成されると共に、前記基板上でそれら各磁気抵抗素子間をループ状に接続する導電体層が形成されており、前記各磁気抵抗素子の磁界に応答し難いピン止め磁性層の磁化方向が、対角の位置関係にある磁気抵抗素子同士では平行、隣接する位置関係にある磁気抵抗素子同士では反平行となっている磁気センサである。４個のスピンバルブ型磁気抵抗素子を、単一基板上で菱形の頂点位置に配列形成することにより、ピン止め磁性層の磁化方向を制御すると共に、基板上でそれら各磁気抵抗素子間を導電体層で接続することが可能となる。
【００１３】
ここでスピンバルブ型磁気抵抗素子は、外部磁界に対し磁化の向きを自由に変えるフリー磁性層と、非磁性金属層と、外部磁界に対し応答し難いピン止め磁性層と、該ピン止め磁性層をピン止めする反強磁性層を積層した構造のスピンバルブ型ＧＭＲ素子、あるいは外部磁界に対し磁化の向きを自由に変えるフリー磁性層と、絶縁層と、外部磁界に対し応答し難いピン止め磁性層と、該ピン止め磁性層をピン止めする反強磁性層を積層した構造のスピンバルブ型トンネルＭＲ素子である。
【００１４】
このような磁気センサは、ピン止め磁性層の上に成膜する反強磁性層がＩｒＭｎやＦｅＭｎのような不規則格子の場合には、ストライプ状に多極着磁した永久磁石板の上に基板を載せ、対角の位置関係にある一対の磁気抵抗素子が同一のストライプ状領域の上に位置し、残りの２個の磁気抵抗素子が前記一対の磁気抵抗素子の両側の逆向きに着磁されたストライプ状領域の上にそれぞれ位置するようにし、その上で磁気抵抗素子の成膜を行うことで製造する。
【００１５】
あるいは、ピン止め磁性層の上に成膜する反強磁性層がＮｉＭｎやＰｄＰｔＭｎ等の規則格子の場合には、ストライプ状に多極着磁した永久磁石板の上に基板を載せ、対角の位置関係にある一対の磁気抵抗素子が同一のストライプ状領域の上に位置し、残りの２個の磁気抵抗素子が前記一対の磁気抵抗素子の両側の逆向きに着磁されたストライプ状領域の上にそれぞれ位置するようにし、その上で磁気抵抗素子の熱処理を行うことにより製造する。
【００１６】
【発明の実施の形態】
スピンバルブ型磁気抵抗素子のピン止め磁性層、反強磁性層の成膜の際、あるいは熱処理の際、各磁気抵抗素子の形状に対応してストライプ状に微小着磁した永久磁石板を用いる。図１に示すように、永久磁石板１０は、着磁方向が１８０度異なり同幅の細長いＡ領域とＢ領域（ここではＡ領域の真上には図面右向きの磁界Ｈが、Ｂ領域の真上には図面左向きの磁界Ｈが発生している）が交互に形成されたものである。本発明で用いる永久磁石板は、１枚の永久磁石平板を上記のように着磁したものでもよいし、幅方向に着磁した細長い永久磁石を多数配列した構成でもよい。図２に示すように、４個の磁気抵抗素子１２（素子▲１▼〜▲４▼）でブリッジを組むとき、前記の永久磁石板１０上に基板を載せ、図３に示すように、例えば素子▲１▼と素子▲４▼がＡ領域の真上に、素子▲２▼と素子▲３▼がそれに隣接するＢ領域の真上に位置するように、即ち各素子が菱形の頂点位置にくるように、基板にパターニングし成膜するか、あるいはそのような状態で熱処理を行う。
【００１７】
すると、素子▲１▼と▲４▼は図４の破線（ａ）で示すような抵抗変化を呈し、素子▲２▼と▲３▼は図４の実線（ｂ）で示すような抵抗変化を呈することになる。そこで、これら各素子間をループ状に導電体膜で結線する。これにより、同一基板上に４個のスピンバルブ型磁気抵抗素子を配列形成し且つ導電体膜でブリッジ結線することが可能となる。図５はスピンバルブ型ＧＭＲ素子を用いた配置例、図６はスピンバルブ型トンネルＭＲ素子を用いた配置例である。なお符号１３は、導電体膜を示している。
【００１８】
スピンバルブ型ＧＭＲ素子の基本膜構成の例を図７に示す。これは、基板２０上に、下地層２２（Ｔａ，Ｚｒ膜）、フリー磁性層２４（ＮｉＦｅ膜又はＣｏＦｅ，Ｃｏ，ＣｏＦｅＢ膜）、非磁性金属層２６（Ｃｕ膜）、固定層２８（ＣｏＦｅ，Ｃｏ，ＣｏＦｅＢ膜又はＮｉＦｅ膜からなるピン止め磁性層３０、及びＦｅＭｎ，ＩｒＭｎ，ＰｔＭｎ膜の反強磁性層３２）、保護層３４（Ｔａ膜）をその順序で積層した構成である。これらの層は全てほぼ同じ矩形形状であり、同じ向きに積層されている。
【００１９】
また、スピンバルブ型トンネルＭＲ素子の基本膜構成の例を図８に示す。これは、基板４０上に、下地層４２（Ｔａ，Ｚｒ膜）、フリー磁性層４４（ＮｉＦｅ膜又はＣｏＦｅ，Ｃｏ，ＣｏＦｅＢ膜）、絶縁層４６（Ａｌ₂Ｏ₃膜）、固定層４８（ＣｏＦｅ，Ｃｏ，ＣｏＦｅＢ膜又はＮｉＦｅ膜からなるピン止め磁性層５０、及びＦｅＭｎ，ＩｒＭｎ，ＰｔＭｎ膜の反強磁性層５２）、保護層５４（Ｔａ膜）を積層した構成である。例えば、横向き細長状で中央が窄まったフリー磁性層４４、円形の絶縁層４６、縦向き細長状で中央が窄まった固定層４８が積層されている。
【００２０】
【実施例】
（実施例１−１）
Ｓｉ基板上に絶縁層ＳｉＯ₂を２０００Å形成する。次に、各素子を菱形配置するためメタルマスクを取り付け、真空チャンバ内にセットする。そして、各素子の長手方向に同一方向に均一磁界が加わるように永久磁石板を配置する。その状態で、下地層（Ｔａ膜）／フリー磁性層（ＮｉＦｅ膜）／非磁性金属層（Ｃｕ膜）を順次成膜する。各膜の厚さは、下地層Ｔａ：５０Å、フリー磁性層ＮｉＦｅ：１２０Å、非磁性金属層Ｃｕ：３０Åである。
【００２１】
次に基板をストライプ着磁した永久磁石上に配置して、真空チャンバ内にセットする。ここでは、予めストライプ着磁した永久磁石板を真空チャンバ内に設置しておき、その上に基板を載せる方法で行った。この状態でピン止め磁性層（ＮｉＦｅ膜）／反強磁性層（ＦｅＭｎ膜）／保護層（Ｔａ膜）を順次成膜する。各膜の厚さは、ピン止め磁性層ＮｉＦｅ：３０Å、反強磁性層ＦｅＭｎ：９０Å、保護層Ｔａ：５０Åである。そして、これらの素子間を接続するようにメタルマスクを施し、導電体層（Ａｇ膜）を形成する。
【００２２】
この試料の電圧印加端子（図１の端子１及び２）に電圧Ｖ（１００ｍＶ）を印加して、出力電圧端子（図１の端子３及び４）間で磁界に対するブリッジ出力電圧を測定した。その結果、図９に示すように、印加磁界に対して出力電圧が変化し、磁界センサとして機能していることが確認できた。
【００２３】
（実施例１−２）
Ｓｉ基板上に絶縁層ＳｉＯ₂を２０００Å形成する。次に、各素子を菱形配置するためメタルマスクを取り付け、真空チャンバ内にセットする。そして、各素子の長手方向に均一磁界が加わるように永久磁石板を配置する。その状態で、下地層（Ｔａ膜）／フリー磁性層（ＮｉＦｅ膜）／非磁性金属層（Ｃｕ膜）を順次成膜する。各膜の厚さは、下地層Ｔａ：５０Å、フリー磁性層ＮｉＦｅ：１２０Å、非磁性金属層Ｃｕ：３０Åである。
【００２４】
次に、基板への磁界が９０度異なるように向きを変えて真空チャンバ内にセットする。ここでは、予め９０度回転させた永久磁石板を真空チャンバ内に設置しておき、その上に基板を載せる方法で行った。この状態でピン止め磁性層（ＮｉＦｅ膜）／反強磁性層（ＦｅＭｎ膜）／保護層（Ｔａ膜）を順次成膜する。各膜の厚さは、ピン止め磁性層ＮｉＦｅ：３０Å、反強磁性層ＦｅＭｎ：９０Å、保護層Ｔａ：５０Åである。そして、これらの素子間を接続するようにメタルマスクを施し、導電体層（Ａｇ膜）を形成する。
【００２５】
反強磁性層でピン止め磁性層を固定している場合は、反強磁性層のネール温度付近の温度から磁場中冷却を施すことにより、磁界方向にピン止め磁性層を固定できる。そこで、上記のように作製した試料を、真空中２００℃で約１時間熱処理し徐冷する。磁界は、ストライプ状に着磁した永久磁石上に基板を配置することで印加する。永久磁石としては、２００℃においても磁界を発生できる２−１７系ＳｍＣｏ磁石を用いた。
【００２６】
この試料の電圧印加端子に電圧Ｖ（１００ｍＶ）を印加し、出力電圧端子間で磁界に対するブリッジ出力電圧を測定した。その結果、図９に示すのと同様、印加磁界に対して出力電圧が変化し、磁界センサとして機能していることが確認できた。
【００２７】
（実施例２−１）
Ｓｉ基板上に絶縁層ＳｉＯ₂を２０００Å形成する。次に各素子を菱形配置するためメタルマスクを取り付け、真空チャンバ内にセットする。そして、各素子の長手方向に垂直に均一磁界が加わるように永久磁石板を配置する。その状態で下地層（Ｔａ膜）／フリー磁性層（ＮｉＦｅ膜＋ＣｏＦｅ膜）を順次成膜する。各膜の厚さは、下地層Ｔａ：５０Å、フリー磁性層ＮｉＦｅ：１２０Å、ＣｏＦｅ：３０Åである。次に絶縁層を成膜する。基板を一旦大気中に取り出し、絶縁層用のマスクに切り替え、真空チャンバ内にセットする。このとき磁界印加用の永久磁石は無くてもよい。ここでＡｌ金属膜を１３Å成膜する。そして大気中に取り出し、室温、大気中で２４０時間保持し、Ａｌ膜を酸化させてＡｌ₂Ｏ₃膜にする。プラズマ酸化や高温酸化してもよい。
【００２８】
その後、基板をストライプ着磁した永久磁石上に配置して、真空チャンバ内にセットする。ここでは、予めストライプ着磁した永久磁石板を真空チャンバ内に設置しておき、その上に基板を載せる方法で行った。この状態でピン止め磁性層（ＣｏＦｅ膜＋ＮｉＦｅ膜）／反強磁性層（ＦｅＭｎ膜）／保護層（Ｔａ膜）を順次成膜する。各膜の厚さは、ピン止め磁性層ＣｏＦｅ：３０Å、ＮｉＦｅ：３０Å、反強磁性層ＦｅＭｎ：９０Å、保護層Ｔａ：５０Åである。そして、これらの素子間を接続するようにメタルマスクを施し、導電体層（Ａｇ膜）を形成する。
【００２９】
この試料の電圧印加端子に電圧Ｖ（１００ｍＶ）を印加し、磁界に対してブリッジ出力電圧を測定した。その結果、図１０に示すように、印加磁界に対して出力電圧が変化し、磁界センサとして機能していることが確認できた。
【００３０】
（実施例２−２）
Ｓｉ基板上に絶縁層ＳｉＯ₂を２０００Å形成する。次に各素子を菱形配置するためメタルマスクを取り付け、真空チャンバ内にセットする。そして、各素子の長手方向に垂直に均一磁界が加わるように永久磁石板を配置する。その状態で下地層（Ｔａ膜）／フリー磁性層（ＮｉＦｅ膜＋ＣｏＦｅ膜）を順次成膜する。各膜の厚さは、下地層Ｔａ：５０Å、フリー磁性層ＮｉＦｅ：１２０Å、ＣｏＦｅ：３０Åである。次に絶縁層を成膜する。基板を一旦大気中に取り出し、絶縁層用のマスクに切り替え、真空チャンバ内にセットする。このとき磁界印加用の永久磁石は無くてもよい。ここでＡｌ金属膜を１３Å成膜する。そして大気中に取り出し、室温、大気中で２４０時間保持し、Ａｌ膜を酸化させてＡｌ₂Ｏ₃膜にする。
【００３１】
その後、基板への磁界が９０度異なるように向きを変えて真空チャンバ内にセットする。ここでは、予め９０度回転させた永久磁石板を真空チャンバ内に設置しておき、その上に基板を載せる方法で行った。この状態でピン止め磁性層（ＣｏＦｅ膜＋ＮｉＦｅ膜）／反強磁性層（ＦｅＭｎ膜）／保護層（Ｔａ膜）を順次成膜する。各膜の厚さは、ピン止め磁性層ＣｏＦｅ：３０Å、ＮｉＦｅ：３０Å、反強磁性層ＦｅＭｎ：９０Å、保護層Ｔａ：５０Åである。そして、これらの素子間を接続するようにメタルマスクを施し、導電体層（Ａｇ膜）を形成する。
【００３２】
反強磁性層でピン止め磁性層を固定している場合は、反強磁性層のネール温度付近の温度から磁場中冷却を施すことにより、磁界方向にピン止め磁性層を固定できる。そこで、上記のように作製した試料を、真空中２００℃で約１時間熱処理し徐冷する。磁界は、ストライプ状に着磁した永久磁石上に基板を配置することで印加する。永久磁石としては、２００℃においても磁界を発生できる２−１７系ＳｍＣｏ磁石を用いた。
【００３３】
この試料の電圧印加端子に電圧Ｖ（１００ｍＶ）を印加し、磁界に対してブリッジ出力電圧を測定した。その結果、図１０に示すのと同様、印加磁界に対して出力電圧が変化し、磁界センサとして機能していることが確認できた。
【００３４】
上記の各実施例においては、素子形成にメタルマスクを用いているが、フォトリソグラフィー技術により作製しても何ら問題はない。実際には、同一基板上に多数の磁気センサを一括して形成し、個々に切り出して製品とする。
【００３５】
【発明の効果】
本発明は上記のように構成した磁気センサであるから、構造が複雑化することなく同一基板上に４個のスピンバルブ型磁気抵抗素子を一括して配列形成してブリッジを組むことができ、小型化に適し、磁界応答性を高くできる。
【００３６】
また本発明によれば、同一基板上に４個のスピンバルブ型磁気抵抗素子を配列形成してブリッジを組んだ小型の磁気センサを、効率よく安価に製造することが可能となる。
【図面の簡単な説明】
【図１】本発明で用いるストライプ状に着磁した永久磁石板の説明図。
【図２】磁気センサにおけるブリッジ構成の説明図。
【図３】本発明におけるストライプ状に着磁した永久磁石板と各スピンバルブ型磁気抵抗素子の位置関係を示す説明図。
【図４】各スピンバルブ型磁気抵抗素子の外部磁界−抵抗値の特性説明図。
【図５】本発明に係るスピンバルブ型ＧＭＲ素子を用いた磁気センサの一例を示す配置接続説明図。
【図６】本発明に係るスピンバルブ型トンネルＭＲ素子を用いた磁気センサの一例を示す配置接続説明図。
【図７】スピンバルブ型ＧＭＲ素子の積層構造の一例を示す説明図。
【図８】スピンバルブ型トンネルＭＲ素子の積層構造の一例を示す説明図。
【図９】本発明に係るスピンバルブ型ＧＭＲ素子を用いた磁気センサの出力特性の一例を示す説明図。
【図１０】本発明に係るスピンバルブ型トンネルＭＲ素子を用いた磁気センサの出力特性の一例を示す説明図。
【符号の説明】
１０永久磁石板
１２スピンバルブ型磁気抵抗素子
１４導電体層[0001]
BACKGROUND OF THE INVENTION
The present invention is, four spin valve-type magneto-resistive element is arranged and formed so as to be located at the apex of the rhombus on a single substrate, a manufacturing method of a magnetic sensor thereof is connected to the looped conductor layer structure It is about. This magnetic sensor is useful, for example, for detection of geomagnetism and a minute positioning sensor.
[0002]
[Prior art]
As an ultra-sensitive magnetic sensor that detects a minute magnetic field, there is a sensor that utilizes the anisotropic magnetoresistive effect (AMR) of a NiFe or CoFe film. This type of magnetic sensor is manufactured by vapor deposition or sputtering so that a large number of magnetic sensors are formed on a substrate by photolithography. Since these magnetic films are sensitive to changes in temperature, a bridge is constructed so as to obtain a differential output.
[0003]
As a method for controlling the anisotropy of the soft magnetic film, there are a method using the shape anisotropy of the element pattern, and an induced magnetic anisotropy by forming a film while applying a magnetic field by a permanent magnet or a magnetic field by energizing a coil. There is a method to give. In a magnetoresistive element using the anisotropic magnetoresistive effect (AMR), the resistance varies with the relative angle between the magnetization direction of the film and the direction of current flow, so that the resistance is symmetric from zero magnetic field to positive and negative magnetic fields. To change. As the magnetic field sensor, a bias magnetic field is applied to the magnetoresistive element so that a differential output is obtained by a bridge circuit, and the response to the magnetic field is made linear.
[0004]
The anisotropic magnetoresistive effect (AMR) has a low resistance change rate (= (resistance change amount / resistance value) × 100%) of 2 to 3%. Therefore, in order to meet the demand for higher sensitivity, GMR ( Magnetic sensors using a spin-valve GMR element utilizing a giant magnetoresistance effect and a spin-valve tunnel MR element utilizing a spin tunnel phenomenon have been proposed.
[0005]
The spin valve type GMR element has a structure in which a free magnetic layer that freely changes the direction of magnetization with respect to an external magnetic field, a nonmagnetic metal layer, and a pinned magnetic layer that is difficult to respond to an external magnetic field are stacked. A phenomenon is used in which the electrical resistance changes depending on the relative angle of the magnetization directions of the two magnetic layers. Such a spin valve type GMR element has excellent linearity with respect to a magnetic field and a high resistance change rate of 5 to 10%.
[0006]
The spin valve tunnel MR element has a structure in which a free magnetic layer that freely changes the direction of magnetization with respect to an external magnetic field, an insulating layer, and a pinned magnetic layer that is difficult to respond to the external magnetic field are laminated. A phenomenon is used in which the tunnel probability of electrons changes depending on the relative angle of the magnetization directions of the two magnetic layers when a voltage is applied between two magnetic layers to tunnel electrons. In order to increase the change in resistance change rate with respect to an external magnetic field, a configuration in which an antiferromagnetic layer (FeMn, NiMn) is laminated adjacent to a ferromagnetic layer has been proposed (see Japanese Patent Laid-Open No. 9-106514). Further, it has been reported that a rate of change of resistance of 10% or more can be obtained in a laminated structure of NiFe / Co / insulating layer (Al—Al ₂ O ₃ ) / Co / NiFe / FeMn (“ferromagnetism having a magnetization fixed layer”). Magnetoresistance effect in tunnel junctions "(see Shigeo Sato, Kazuo Kobayashi, Journal of Applied Magnetics Society of Japan 21,489-492 (1997)).
[0007]
In these spin-valve magnetoresistive elements, the linear operation direction with respect to the magnetic field can be changed by the magnetization direction of the pinned magnetic layer. This pinned magnetic layer fixes the magnetization direction by laminating antiferromagnetic materials (FeMn, NiMn, IrMn, PdPtMn, etc.) adjacent to each other.
[0008]
[Problems to be solved by the invention]
To form a bridge with four spin-valve magnetoresistive elements and obtain a differential output with respect to the magnetic field, the magnetization direction of the pinned magnetic layer that is difficult to respond to the magnetic field is changed by 180 degrees between adjacent elements. There must be. The magnetization direction of the pinned magnetic layer is determined by an antiferromagnetic film formed thereon. The magnetization direction is defined by the direction of the magnetic field applied on the substrate surface during film formation, and is defined by the magnetic field direction in the heat treatment in the magnetic field from near the Neel temperature of the antiferromagnetic film.
[0009]
A magnetic field during film formation or heat treatment is given by a permanent magnet or an electromagnet, and a uniform magnetic field in one direction is applied on the substrate. Therefore, spin valve magnetoresistive elements in which the magnetization direction of the pinned magnetic layer is changed by 180 degrees cannot be mixed on the same substrate. Therefore, a magnetic sensor in which a bridge is assembled is usually assembled by taking individual spin-valve magnetoresistive elements from the substrate and wiring them with lead wires or the like. If it does so, processes, such as wiring, will increase, it will prevent miniaturization and it will become difficult also in terms of packaging.
[0010]
As a technique for solving such a problem, a conductor layer is formed on a magnetic sensor having a bridge formed on the same substrate through an insulator layer, and a magnetic field is generated by energizing the conductor layer. A method for changing the magnetization direction of the pinned magnetic layer by 180 degrees has been proposed (see Japanese Patent Application Laid-Open No. 8-226960). However, this method has a problem that the configuration is complicated.
[0011]
An object of the present invention is to provide four manufacturing method of the magnetic sensor of the spin valve-type magneto-resistive element partnered bridge by arranging formed on the same substrate.
[0012]
[Means for Solving the Problems]
In the present invention, four spin-valve magnetoresistive elements are arrayed and formed at rhombus apex positions on a single substrate, and a conductor layer that connects the magnetoresistive elements in a loop shape on the substrate is provided. The magnetization directions of the pinned magnetic layers that are formed and are difficult to respond to the magnetic field of each of the magnetoresistive elements are parallel to each other in the magnetoresistive elements in a diagonal position relationship, and between the magnetoresistive elements in the adjacent positional relationship. The magnetic sensor is antiparallel. By arranging four spin-valve magnetoresistive elements at the top of the rhombus on a single substrate, the magnetization direction of the pinned magnetic layer is controlled and the magnetoresistive elements are electrically connected on the substrate. It becomes possible to connect in the body layer.
[0013]
Here, the spin valve magnetoresistive element includes a free magnetic layer that freely changes the magnetization direction with respect to an external magnetic field, a nonmagnetic metal layer, a pinned magnetic layer that is difficult to respond to an external magnetic field, and the pinned magnetic layer Valve-type GMR element with a laminated antiferromagnetic layer to pin, or a free magnetic layer that freely changes the direction of magnetization with respect to an external magnetic field, an insulating layer, and pinning magnetism that is difficult to respond to an external magnetic field This is a spin valve tunnel MR element having a structure in which a layer and an antiferromagnetic layer for pinning the pinned magnetic layer are stacked.
[0014]
In such a magnetic sensor, when the antiferromagnetic layer formed on the pinned magnetic layer is an irregular lattice such as IrMn or FeMn, the magnetic sensor is formed on a striped multi-pole magnetized permanent magnet plate. A pair of magnetoresistive elements in a diagonal position are placed on the same stripe region, and the remaining two magnetoresistive elements are attached in opposite directions on both sides of the pair of magnetoresistive elements. The magnetoresistive element is formed on each of the magnetized stripe regions, and the magnetoresistive element is formed thereon.
[0015]
Alternatively, when the antiferromagnetic layer formed on the pinned magnetic layer is a regular lattice such as NiMn or PdPtMn, a substrate is placed on a permanent magnet plate magnetized in a striped manner so as to form a diagonal pattern. A pair of magnetoresistive elements in a positional relationship are positioned on the same stripe region, and the remaining two magnetoresistive elements are magnetized in opposite directions on both sides of the pair of magnetoresistive elements. The magnetoresistive element is manufactured by performing heat treatment on the magnetoresistive element.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
When the pinned magnetic layer and the antiferromagnetic layer of the spin valve magnetoresistive element are formed, or when heat treatment is performed, a permanent magnet plate that is minutely magnetized in a stripe shape corresponding to the shape of each magnetoresistive element is used. As shown in FIG. 1, the permanent magnet plate 10 has an elongated A region and B region that are 180 degrees different in magnetization direction and have the same width (here, a magnetic field H facing right in the drawing is directly above the A region, On the upper side, a magnetic field H directed to the left of the figure is generated). The permanent magnet plate used in the present invention may be a single permanent magnet flat plate magnetized as described above, or may have a configuration in which a number of elongated permanent magnets magnetized in the width direction are arranged. As shown in FIG. 2, when a bridge is formed by four magnetoresistive elements 12 (elements (1) to (4)), a substrate is placed on the permanent magnet plate 10, and as shown in FIG. The elements (1) and (4) are positioned directly above the A area, and the elements (2) and (3) are positioned immediately above the B area adjacent to the elements, that is, each element is positioned at the apex of the rhombus. Then, patterning is performed on the substrate to form a film, or heat treatment is performed in such a state.
[0017]
Then, the elements {circle around (1)} and {circle around (4)} exhibit resistance changes as indicated by broken lines (a) in FIG. 4, and the elements {circle around (2)} and {circle around (3)} exhibit resistance changes as indicated by solid lines (b) in FIG. Will be presented. Therefore, these elements are connected by a conductor film in a loop shape. As a result, four spin-valve magnetoresistive elements can be arrayed on the same substrate and bridged with the conductor film. FIG. 5 shows an arrangement example using a spin valve type GMR element, and FIG. 6 shows an arrangement example using a spin valve type tunnel MR element. Reference numeral 13 denotes a conductor film.
[0018]
An example of the basic film configuration of the spin valve GMR element is shown in FIG. This is because a base layer 22 (Ta, Zr film), a free magnetic layer 24 (NiFe film or CoFe, Co, CoFeB film), a nonmagnetic metal layer 26 (Cu film), a fixed layer 28 (CoFe, The pinned magnetic layer 30 made of Co, CoFeB film or NiFe film, the antiferromagnetic layer 32 of FeMn, IrMn, PtMn film) and the protective layer 34 (Ta film) are laminated in that order. All of these layers have substantially the same rectangular shape and are stacked in the same direction.
[0019]
FIG. 8 shows an example of the basic film configuration of the spin valve type tunnel MR element. This is because an underlayer 42 (Ta, Zr film), a free magnetic layer 44 (NiFe film or CoFe, Co, CoFeB film), an insulating layer 46 (Al ₂ O ₃ film), and a fixed layer 48 (CoFe) are formed on the substrate 40. , Co, CoFeB film or NiFe film, pinned magnetic layer 50, FeMn, IrMn, PtMn film antiferromagnetic layer 52) and protective layer 54 (Ta film). For example, a free magnetic layer 44 having a horizontally elongated shape and a narrowed center, a circular insulating layer 46, and a vertically elongated shape and a fixed layer 48 having a narrowed center are stacked.
[0020]
【Example】
(Example 1-1)
An insulating layer of SiO ₂ is formed on the Si substrate. Next, in order to arrange each element in a diamond shape, a metal mask is attached and set in a vacuum chamber. And a permanent magnet board is arrange | positioned so that a uniform magnetic field may be added to the longitudinal direction of each element in the same direction. In this state, a base layer (Ta film) / free magnetic layer (NiFe film) / nonmagnetic metal layer (Cu film) are sequentially formed. The thickness of each film is the base layer Ta: 50 ：, the free magnetic layer NiFe: 120Å, and the nonmagnetic metal layer Cu: 30Å.
[0021]
Next, the substrate is placed on a permanent magnet with stripes and set in a vacuum chamber. Here, a permanent magnet plate preliminarily stripe-magnetized was placed in a vacuum chamber, and a substrate was placed thereon. In this state, a pinned magnetic layer (NiFe film) / antiferromagnetic layer (FeMn film) / protective layer (Ta film) are sequentially formed. The thickness of each film is a pinned magnetic layer NiFe: 30 mm, an antiferromagnetic layer FeMn: 90 mm, and a protective layer Ta: 50 mm. Then, a metal mask is applied so as to connect these elements, and a conductor layer (Ag film) is formed.
[0022]
The voltage V (100 mV) was applied to the voltage application terminals (terminals 1 and 2 in FIG. 1) of this sample, and the bridge output voltage against the magnetic field was measured between the output voltage terminals (terminals 3 and 4 in FIG. 1). As a result, as shown in FIG. 9, it was confirmed that the output voltage changed with respect to the applied magnetic field and functioned as a magnetic field sensor.
[0023]
(Example 1-2)
An insulating layer of SiO ₂ is formed on the Si substrate. Next, in order to arrange each element in a diamond shape, a metal mask is attached and set in a vacuum chamber. And a permanent magnet board is arrange | positioned so that a uniform magnetic field may be added to the longitudinal direction of each element. In this state, a base layer (Ta film) / free magnetic layer (NiFe film) / nonmagnetic metal layer (Cu film) are sequentially formed. The thickness of each film is the base layer Ta: 50 ：, the free magnetic layer NiFe: 120Å, and the nonmagnetic metal layer Cu: 30Å.
[0024]
Next, the orientation is changed so that the magnetic field to the substrate differs by 90 degrees, and the substrate is set in the vacuum chamber. Here, a permanent magnet plate rotated in advance by 90 degrees was placed in a vacuum chamber, and a substrate was placed thereon. In this state, a pinned magnetic layer (NiFe film) / antiferromagnetic layer (FeMn film) / protective layer (Ta film) are sequentially formed. The thickness of each film is a pinned magnetic layer NiFe: 30 mm, an antiferromagnetic layer FeMn: 90 mm, and a protective layer Ta: 50 mm. Then, a metal mask is applied so as to connect these elements, and a conductor layer (Ag film) is formed.
[0025]
When the pinned magnetic layer is pinned with an antiferromagnetic layer, the pinned magnetic layer can be pinned in the magnetic field direction by cooling in a magnetic field from a temperature near the Neel temperature of the antiferromagnetic layer. Therefore, the sample prepared as described above is heat-treated in a vacuum at 200 ° C. for about 1 hour and gradually cooled. The magnetic field is applied by arranging the substrate on a permanent magnet magnetized in a stripe shape. As the permanent magnet, a 2-17 SmCo magnet capable of generating a magnetic field even at 200 ° C. was used.
[0026]
The voltage V (100 mV) was applied to the voltage application terminal of this sample, and the bridge output voltage with respect to the magnetic field was measured between the output voltage terminals. As a result, as shown in FIG. 9, it was confirmed that the output voltage changed with respect to the applied magnetic field and functioned as a magnetic field sensor.
[0027]
(Example 2-1)
An insulating layer of SiO ₂ is formed on the Si substrate. Next, in order to arrange each element in a diamond shape, a metal mask is attached and set in a vacuum chamber. And a permanent magnet plate is arrange | positioned so that a uniform magnetic field may be applied perpendicularly to the longitudinal direction of each element. In this state, a base layer (Ta film) / free magnetic layer (NiFe film + CoFe film) are sequentially formed. The thickness of each film is the under layer Ta: 50Ｔａ, the free magnetic layer NiFe: 120Å, and CoFe: 30Å. Next, an insulating layer is formed. The substrate is once taken out into the atmosphere, switched to a mask for an insulating layer, and set in a vacuum chamber. At this time, there may be no permanent magnet for applying a magnetic field. Here, 13 Al metal films are formed. And taken out into the atmosphere, at room temperature, and held for 240 hours in the atmosphere, which was oxidized Al film to the Al ₂ O ₃ film. Plasma oxidation or high temperature oxidation may be performed.
[0028]
After that, the substrate is placed on a permanent magnet magnetized in stripes and set in a vacuum chamber. Here, a permanent magnet plate preliminarily stripe-magnetized was placed in a vacuum chamber, and a substrate was placed thereon. In this state, a pinned magnetic layer (CoFe film + NiFe film) / antiferromagnetic layer (FeMn film) / protective layer (Ta film) is sequentially formed. The thickness of each film is the pinned magnetic layer CoFe: 30 Å, NiFe: 30 Å, the antiferromagnetic layer FeMn: 90 Å, and the protective layer Ta: 50 Å. Then, a metal mask is applied so as to connect these elements, and a conductor layer (Ag film) is formed.
[0029]
A voltage V (100 mV) was applied to the voltage application terminal of this sample, and the bridge output voltage was measured against the magnetic field. As a result, as shown in FIG. 10, it was confirmed that the output voltage changed with respect to the applied magnetic field and functioned as a magnetic field sensor.
[0030]
(Example 2-2)
An insulating layer of SiO ₂ is formed on the Si substrate. Next, in order to arrange each element in a diamond shape, a metal mask is attached and set in a vacuum chamber. And a permanent magnet plate is arrange | positioned so that a uniform magnetic field may be applied perpendicularly to the longitudinal direction of each element. In this state, a base layer (Ta film) / free magnetic layer (NiFe film + CoFe film) are sequentially formed. The thickness of each film is the under layer Ta: 50Ｔａ, the free magnetic layer NiFe: 120Å, and CoFe: 30Å. Next, an insulating layer is formed. The substrate is once taken out into the atmosphere, switched to a mask for an insulating layer, and set in a vacuum chamber. At this time, there may be no permanent magnet for applying a magnetic field. Here, 13 Al metal films are formed. And taken out into the atmosphere, at room temperature, and held for 240 hours in the atmosphere, which was oxidized Al film to the Al ₂ O ₃ film.
[0031]
Thereafter, the direction is changed so that the magnetic field to the substrate is different by 90 degrees, and the substrate is set in the vacuum chamber. Here, a permanent magnet plate rotated in advance by 90 degrees was placed in a vacuum chamber, and a substrate was placed thereon. In this state, a pinned magnetic layer (CoFe film + NiFe film) / antiferromagnetic layer (FeMn film) / protective layer (Ta film) is sequentially formed. The thickness of each film is the pinned magnetic layer CoFe: 30 Å, NiFe: 30 Å, the antiferromagnetic layer FeMn: 90 Å, and the protective layer Ta: 50 Å. Then, a metal mask is applied so as to connect these elements, and a conductor layer (Ag film) is formed.
[0032]
When the pinned magnetic layer is pinned with an antiferromagnetic layer, the pinned magnetic layer can be pinned in the magnetic field direction by cooling in a magnetic field from a temperature near the Neel temperature of the antiferromagnetic layer. Therefore, the sample prepared as described above is heat-treated in a vacuum at 200 ° C. for about 1 hour and gradually cooled. The magnetic field is applied by arranging the substrate on a permanent magnet magnetized in a stripe shape. As the permanent magnet, a 2-17 SmCo magnet capable of generating a magnetic field even at 200 ° C. was used.
[0033]
A voltage V (100 mV) was applied to the voltage application terminal of this sample, and the bridge output voltage was measured against the magnetic field. As a result, as shown in FIG. 10, it was confirmed that the output voltage changed with respect to the applied magnetic field and functioned as a magnetic field sensor.
[0034]
In each of the above embodiments, a metal mask is used for element formation, but there is no problem even if it is produced by photolithography. In practice, a large number of magnetic sensors are collectively formed on the same substrate and cut into individual products.
[0035]
【The invention's effect】
Since the present invention is a magnetic sensor configured as described above, it is possible to form a bridge by collectively arranging four spin valve magnetoresistive elements on the same substrate without complicating the structure, Suitable for miniaturization and high magnetic field response.
[0036]
Further, according to the present invention, it is possible to efficiently and inexpensively manufacture a small magnetic sensor in which four spin-valve magnetoresistive elements are arrayed on the same substrate to form a bridge.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a permanent magnet plate magnetized in a stripe shape used in the present invention.
FIG. 2 is an explanatory diagram of a bridge configuration in a magnetic sensor.
FIG. 3 is an explanatory diagram showing a positional relationship between a permanent magnet plate magnetized in a stripe shape and each spin-valve magnetoresistive element in the present invention.
FIG. 4 is a characteristic explanatory diagram of external magnetic field-resistance value of each spin-valve magnetoresistive element.
FIG. 5 is an explanatory diagram of arrangement connection showing an example of a magnetic sensor using a spin valve type GMR element according to the present invention.
FIG. 6 is an explanatory diagram of arrangement connection showing an example of a magnetic sensor using a spin valve type tunnel MR element according to the present invention.
FIG. 7 is an explanatory diagram showing an example of a laminated structure of spin valve GMR elements.
FIG. 8 is an explanatory diagram showing an example of a laminated structure of a spin valve type tunnel MR element.
FIG. 9 is an explanatory diagram showing an example of output characteristics of a magnetic sensor using a spin valve type GMR element according to the present invention.
FIG. 10 is an explanatory diagram showing an example of output characteristics of a magnetic sensor using a spin valve type tunnel MR element according to the present invention.
[Explanation of symbols]
10 Permanent Magnet Plate 12 Spin Valve Magnetoresistive Element 14 Conductor Layer

Claims

With four spin-valve type magnetoresistive element is arranged and formed on the apex position of the diamond-shaped on a single substrate, the conductor layer for connecting them each magnetoresistive element in a loop on said substrate is formed The magnetization direction of the pinned magnetic layer that is difficult to respond to the magnetic field of each of the magnetoresistive elements is parallel between the magnetoresistive elements in the diagonal positional relationship, and antiparallel between the magnetoresistive elements in the adjacent positional relationship. A magnetic sensor is manufactured by placing a substrate on a multi-pole magnetized permanent magnet plate in a stripe shape, and a pair of magnetoresistive elements in a diagonal position relationship in the same stripe region. The remaining two magnetoresistive elements are arranged at the apexes of the rhombus so that the remaining two magnetoresistive elements are respectively positioned on the stripe-shaped regions magnetized in opposite directions on both sides of the pair of magnetoresistive elements. To form magnetoresistive element Manufacturing method of a magnetic sensor, characterized in that.

With four spin-valve type magnetoresistive element is arranged and formed on the apex position of the diamond-shaped on a single substrate, the conductor layer for connecting them each magnetoresistive element in a loop on said substrate is formed The magnetization direction of the pinned magnetic layer that is difficult to respond to the magnetic field of each of the magnetoresistive elements is parallel between the magnetoresistive elements in the diagonal positional relationship, and antiparallel between the magnetoresistive elements in the adjacent positional relationship. A magnetic sensor is manufactured by placing a substrate on a multi-pole magnetized permanent magnet plate in a stripe shape, and a pair of magnetoresistive elements in a diagonal position relationship in the same stripe region. The remaining two magnetoresistive elements are arranged at the apexes of the rhombus so that the remaining two magnetoresistive elements are respectively positioned on the stripe-shaped regions magnetized in opposite directions on both sides of the pair of magnetoresistive elements. Heat treatment of the magnetoresistive element Method of producing a magnetic sensor characterized by Ukoto.

A spin valve magnetoresistive element includes a free magnetic layer that freely changes the direction of magnetization with respect to an external magnetic field, a nonmagnetic metal layer, a pinned magnetic layer that is difficult to respond to an external magnetic field, and a pinned magnetic layer 3. The method of manufacturing a magnetic sensor according to claim 1, wherein the spin valve type GMR element has a structure in which an antiferromagnetic layer to be stopped is laminated.

A spin-valve magnetoresistive element pins a free magnetic layer that freely changes the direction of magnetization with respect to an external magnetic field, an insulating layer, a pinned magnetic layer that is difficult to respond to an external magnetic field, and the pinned magnetic layer 3. The method of manufacturing a magnetic sensor according to claim 1, wherein the magnetic field sensor is a spin valve tunnel MR element having a structure in which an antiferromagnetic layer is laminated.