JP3964055B2 - Magnetoresistive element sensor, potentiometer and encoder using the same, and method for manufacturing magnetoresistive element sensor - Google Patents

Magnetoresistive element sensor, potentiometer and encoder using the same, and method for manufacturing magnetoresistive element sensor Download PDF

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JP3964055B2
JP3964055B2 JP21518398A JP21518398A JP3964055B2 JP 3964055 B2 JP3964055 B2 JP 3964055B2 JP 21518398 A JP21518398 A JP 21518398A JP 21518398 A JP21518398 A JP 21518398A JP 3964055 B2 JP3964055 B2 JP 3964055B2
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magnetoresistive
magnetic layer
elements
effect element
magnetoresistive effect
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義人 佐々木
隆史 畑内
彰宏 牧野
一郎 徳永
誠二 菊池
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Alps Alpine Co Ltd
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Alps Electric Co Ltd
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Description

【０００１】
【発明の属する技術分野】
本発明は、エンコーダやポテンショメータなどの位置センサあるいは速度センサ等に使用される磁気抵抗効果素子センサに係り、特に出力を増大でき、さらに容易に前記磁気抵抗効果素子センサを製造することが可能な磁気抵抗効果素子センサ及びその製造方法に関する。
【０００２】
【従来の技術】
磁気抵抗効果素子としては、異方性磁気抵抗効果現象を用いたＡＭＲ（Anisotropic Magnetoresistance）素子と、伝導電子のスピン依存散乱現象を用いたＧＭＲ（Giant Magnetoresistance：巨大磁気抵抗効果）素子とがあり、前記ＧＭＲ素子の中でも構造が比較的単純で、且つ抵抗変化率の高いものとしてスピンバルブ素子を挙げることができる。
前記スピンバルブ素子は、最も単純な構造で４層からなり、例えば下から反強磁性層、固定磁性層（ピン磁性層）、非磁性導電層、及びフリー磁性層で形成される。
【０００３】
前記固定磁性層及びフリー磁性層としては、Ｎｉ―Ｆｅ合金膜（パーマロイ）やＣｏが使用され、また非磁性導電層としては、Ｃｕ膜（銅）が一般的に使用されている。反強磁性層としては、従来からＦｅＭｎやＮｉＭｎ合金膜が使用され、前記反強磁性層と固定磁性層との界面での交換結合磁界によって、前記固定磁性層の磁化が一定方向に固定されるようになっている。
フリー磁性層の磁化は、外部磁界の影響を受けて自由に反転するようになっており、前記固定磁性層の磁化方向とフリー磁性層の磁化方向との変動によって抵抗値が変化し、電圧変化として出力する。
【０００４】
このように外部磁界の影響を受けて抵抗値が変化するスピンバルブ素子を、例えば角度センサのポテンショメータに使用し、その回路図を表したのが図１５である。
図１５に示す符号１及び２は、磁気抵抗効果素子（スピンバルブ素子）を示している。図１５に示すように２つの磁気抵抗効果素子１，２を直列に接続し、前記磁気抵抗効果素子１，２の中間に出力端子４を設ける。磁気抵抗効果素子１，２に示されている矢印５，６は各磁気抵抗効果素子１，２の固定磁性層の磁化方向を示しており、例えば図１５に示すように前記磁気抵抗効果素子１の固定磁性層の磁化５は、図示下方向に、磁気抵抗効果素子２の固定磁性層の磁化６は図示上向きに固定されている。
【０００５】
ポテンショメータの磁石のＮ極とＳ極が図１５に示す位置にあると、磁気抵抗効果素子１，２のフリー磁性層は、前記磁石から発生する磁界９の影響を受けて、前記フリー磁性層の磁化７，８は、磁石からの磁界の方向と同一方向に向く。
【０００６】
磁気抵抗効果素子１，２は、固定磁性層とフリー磁性層の磁化方向が、同じ向きに向けられているときに最も抵抗値は小さくなり、前記磁化方向が逆向き、すなわち１８０度に近づくにつれて抵抗値が大きくなる。図１５に示す場合では、磁気抵抗効果素子２の方が、磁気抵抗効果素子１よりも抵抗値が大きい状態になり、入力端子３の電位が例えば５Ｖであると、出力端子４からは２．５Ｖ以上の出力を得られる。
ポテンショメータの磁石を回転させると、各磁気抵抗効果素子１，２の抵抗値は変化するが、このときの磁気抵抗効果素子１，２の抵抗値の差により出力を得ることによって、角度センサとして機能する。
【０００７】
【発明が解決しようとする課題】
ところで前述したように、従来では磁気抵抗効果素子１，２の反強磁性層としてＦｅＭｎやＮｉＭｎ合金膜などが使用されていたが、この反強磁性材料は、磁場中アニール（熱処理）を施さないと、固定磁性層との界面で交換結合磁界が発生せず、従って前記磁気抵抗効果素子１，２を、基板上に成膜した後に、磁場中でアニール処理を施す必要性がある。
【０００８】
ところが、前記磁気抵抗効果素子１，２を、基板上に２個形成し、さらに前記磁気抵抗効果効果素子１，２を一直線上に接続した場合に、磁場中で熱処理を施すと、反強磁性層と固定磁性層との界面で発生する交換結合磁界は、前記磁気抵抗効果素子１，２共に同じ方向に発生し、従って、前記磁気抵抗効果素子１，２の固定磁性層は、共に同じ方向に磁化されてしまい、図１５の回路図のように、前記磁気抵抗効果素子１，２の固定磁性層の磁化５，６を互いに反平行（逆方向）に向けるのは、非常に困難となる。
【０００９】
前記固定磁性層の磁化方向５，６が、共に同じ向きに固定されてしまうと、ポテンショメータの磁石の回転によって変動するフリー磁性層の磁化方向７，８と、前記固定磁性層の磁化方向５，６との角度が、磁気抵抗効果素子１と２で常に同じになってしまい、出力端子４から得られる出力は一定値となり、角度センサとしての機能を果たすことができない。
【００１０】
このように従来では、熱処理を施すことによって、固定磁性層との界面で交換結合磁界を発生させることができるＮｉＭｎ合金などの反強磁性層を使用した場合には、基板上に複数の磁気抵抗効果素子を形成し、同時に前記磁気抵抗効果素子の固定磁性層を適正な（異なる）方向に磁化することはできない。
さらに、反強磁性層に、ＦｅＭｎやＮｉＭｎ合金などの導電性反強磁性層を使用すると、反強磁性層に検出電流が分流するシャント効果により、抵抗変化率はそれほど高くない。
【００１１】
本発明では上記従来の問題点を解決するためのものであり、反強磁性層の材質、及び磁気抵抗効果素子の形成位置等を適正化することにより、磁気抵抗効果素子センサに４個の磁気抵抗効果素子を形成してもなお製造工程を容易にすることができ、しかも出力を増大させることが可能な磁気抵抗効果素子センサと、これを使用するポテンショメータ並びにエンコーダ、及び磁気抵抗効果センサの製造方法を提供することを目的としている。
【００１２】
【課題を解決するための手段】
本発明における磁気抵抗効果素子センサは、基板上に、固定磁性層と、外部磁界の影響を受けて磁化方向が変動するフリー磁性層とを有する磁気抵抗効果素子が４個設けられ、この４個の磁気抵抗効果素子のうち２個の磁気抵抗効果素子は、その固定磁性層が同一方向に磁化されて、第１の磁気抵抗効果素子と第４の磁気抵抗効果素子とされ、また残りの２個の磁気抵抗効果素子は、その固定磁性層が、前記第１と第４の磁気抵抗効果素子の固定磁性層と逆向きに磁化されて、第２の磁気抵抗効果素子と第３の磁気抵抗効果素子とされており、前記第１の磁気抵抗効果素子と第２の磁気抵抗効果素子、及び第３の磁気抵抗効果素子と第４の磁気抵抗効果素子が、磁気抵抗効果素子間に、出力部を有して直列に接続された状態で、前記２つの直列回路が並列に接続されており、各直列回路の両端が入力部とされており、
前記第１の磁気抵抗効果素子と前記第４の磁気抵抗効果素子とが、固定磁性層の磁化方向を互いに平行に向けて、基板の一方の側に配置され、前記第２の磁気抵抗効果素子と前記第３の磁気抵抗効果素子とが、固定磁性層の磁化方向を互いに平行で、且つ、前記第１の磁気抵抗効果素子と前記第４の磁気抵抗効果素子の固定磁性層の磁化方向と逆方向に向けて、基板の他方の側に配置されていることを特徴とするものである。
【００１４】
また本発明は、前記磁気抵抗効果素子センサは、前記磁気抵抗効果素子センサと磁石とを平行に配置し、前記磁石を、前記磁気抵抗効果素子センサの基板に垂直な軸を中心として回転させることで、前記基板上の磁気抵抗効果素子間の抵抗変化の作動を計測するポテンショメータとして使用することができる。
【００１５】
さらに本発明における磁気抵抗効果素子センサは、基板上に、固定磁性層と、外部磁界の影響を受けて磁化方向が変動するフリー磁性層とを有する磁気抵抗効果素子が４個設けられ、４個の磁気抗効果素子は、その固定磁性層がすべて同一方向に磁化され、且つ、各固定磁性層の磁化方向に向けて、一列に配列されており、２個の磁気抵抗効果素子が、両素子間に出力部を有して直列に接続され、他の２個の磁気抵抗効果素子が、両素子間に出力部を有して直列に接続されており、前記２つの直列回路が並列に接続されて、直列回路の両端が入力部とされており、
前記一列に配置された４個の磁気抵抗効果素子のうち、片側から数えて、１番目と３番目に形成された磁気抵抗効果素子が、互いに直列に接続され、また２番目と４番目に形成された磁気抵抗効果素子が、互いに直列に接続されていることを特徴とするものである。
【００１７】
本発明は、前記磁気抵抗効果素子センサが、回転方向にＮ極とＳ極とが交互に形成された回転ドラムに対向して配置されており、前記回転ドラムを回転させることで、前記磁気抵抗効果素子センサに形成された磁気抵抗効果素子間の抵抗変化を計測するエンコーダとして使用することができる。
また本発明では、前記Ｎ極とＳ極との間隔は、磁気抵抗効果素子センサ上に一列に配置された各磁気抵抗効果素子の間隔の２倍に形成されていることが好ましい。
【００１８】
ところで本発明では、磁気抵抗効果素子の固定磁性層の保磁力は、フリー磁性層の保磁力に比べて大きくなっている必要性があり、例えば、前記固定磁性層に接する一方の層には、反強磁性層が形成され、前記反強磁性層は、α―Ｆｅ2Ｏ3で形成されていることが好ましい。あるいは、前記固定磁性層は、硬磁性材料で形成されていてもよい。
【００１９】
また本発明は、磁気抵抗効果素子センサの製造方法において、
固定磁性層と、外部磁界の影響を受けて磁化が変動するフリー磁性層とを有する磁気抵抗効果素子を４個基板上に形成し、このとき、基板の一方の側に第１の磁気抵抗効果素子と第２の磁気抵抗効果素子を並べて配置し、基板の他方の側に第３の磁気抵抗効果素子と第４の磁気抵抗効果素子を並べて配置する工程と、
前記第１の磁気抵抗効果素子と第２の磁気抵抗効果素子、及び第３の磁気抵抗効果素子と第４の磁気抵抗効果素子を、素子の中間に出力部を有するように直列に接続する工程と、
前記２つの直列回路を並列に接続すると共に、直列回路の両端に入力部を形成する工程と、
第１の磁気抵抗効果素子と第４の磁気抵抗効果素子の上、及び第２の磁気抵抗効果素子と第３の磁気抵抗効果素子の上にそれぞれ導線を配置し、２本の導線に流す電流の方向を逆向きとして、第１の磁気抵抗効果素子と第４の磁気抵抗効果素子の固定磁性層の磁化と、第２の磁気抵抗効果素子と第３の磁気抵抗効果素子の固定磁性層の磁化とを逆向きに固定する工程と、
を有することを特徴とするものである。
【００２０】
さらに本発明は、磁気抵抗効果素子センサの製造方法において、
固定磁性層と、外部磁界の影響を受けて磁化が変動するフリー磁性層とを有する磁気抵抗効果素子を、基板上に４個一列に形成する工程と、
片側から数えて、１番目と３番目の磁気抵抗効果素子を両素子間に出力部を形成して直列に接続する工程と、
２番目と４番目の磁気抵抗効果素子を両素子間に出力部を形成して直列に接続する工程と、
前記２つの直列回路を並列に接続し、直列回路の両端に入力部を形成する工程と、
前記４個の磁気抵抗効果素子に対して、その配列方向に向く磁場を与えて、全ての磁気抵抗効果素子の固定磁性層を同じ方向に磁化させることを特徴とするものである。
【００２１】
本発明では、前記４個の磁気抵抗効果素子のそれぞれの上に導線を配置し、前記導線に電流を流すことによって、前記４個の磁気抵抗効果素子の固定磁性層を同じ方向に磁化させることが好ましい。
【００２２】
さらに本発明では、前記磁気抵抗効果素子の固定磁性層に接する一方の層をα―Ｆｅ2Ｏ3で形成された反強磁性層で形成することが好ましく、あるいは、前記磁気抵抗効果素子の固定磁性層を、ＣｏＰｔ、ＣｏＰｔＣｒ合金等から成る硬磁性材料で形成してもよい。
【００２３】
磁気抵抗効果素子の反強磁性層として従来から使用されていたＦｅＭｎやＮｉＭｎ合金膜は成膜段階では、固定磁性層との界面で交換結合磁界が発生せず、成膜後磁場中アニール（熱処理）を施すことにより、前記固定磁性層との界面で交換結合磁界が発生し、固定磁性層の磁化がある一定方向に固定される。
【００２４】
反強磁性層がＮｉＭｎ合金膜で形成された場合のＲ―Ｈ曲線を示すのが図１４である。なお横軸は外部磁界を示しており、原点よりも左側では前記外部磁界は図示左方向に加わり、原点よりも右側では、前記外部磁界は図示右方向に加わるものとする。
【００２５】
まず図１４に示す段階Ａの部分では、抵抗値Ｒが、ほとんど０となっているが、これは、磁気抵抗効果素子の固定磁性層及びフリー磁性層の磁化が共に左方向に磁化されているからである。図示左方向の外部磁界が弱まり、前記外部磁界が図示右方向に加わり始める原点付近で、抵抗値Ｒが上がり出す段階Ｂとなる。段階Ｂでは、左方向に磁化されていたフリー磁性層の磁化が、外部磁界の影響を受けて、フリー磁性層の磁化方向が変動し、固定磁性層の磁化方向との間で角度差が生じることで、抵抗値Ｒが急激に上昇する。
【００２６】
段階Ｃになると、抵抗値Ｒが下がり始めるが、これは、図示左方向に固定されていた固定磁性層の磁化が、図示右方向に働く外部磁界の影響を受けて、徐々に図示右方向に変動し始め、段階Ｃの時点で、完全に図示右方向に磁化されているフリー磁性層との間で、磁化方向の角度差が徐々に小さくなり、抵抗値Ｒが低下し始める。
【００２７】
段階Ｄになると、図示右方向の外部磁界が弱まることにより、図示右方向に磁化されていた固定磁性層の磁化が、反強磁性層との交換結合磁界による磁化方向、すなわち図示左方向に傾き始め、さらに段階Ｂ、段階Ａをたどるヒステリシスループを描く。図１４に示すＥの幅が、固定磁性層の保磁力を表している。
一方、本発明では、磁気抵抗効果素子の反強磁性層として、α―Ｆｅ2Ｏ3（α―フェマタイト）が使用される。反強磁性層がα―Ｆｅ2Ｏ3膜で形成された場合のＲ―Ｈ曲線を示すのが図１３である。なお横軸は外部磁界を示しており、原点よりも左側では前記外部磁界は図示左方向に加わり、原点よりも右側では、前記外部磁界は図示右方向に加わるものとする。
【００２８】
まず図１３に示す段階Ｆでは、磁気抵抗効果素子層の固定磁性層及びフリー磁性層の磁化方向が共に図示左方向を向いており、抵抗値Ｒは非常に低い状態となっている。
図示左方向の外部磁界が弱まり始め、外部磁界が図示右方向に移行する原点付近で、フリー磁性層の磁化が、前記外部磁界の影響を受けて変動することにより、抵抗値Ｒが高くなり始め、段階Ｇになる。さらに図示右方向に外部磁界を強めると、図示左方向に磁化されていた固定磁性層の磁化が、前記外部磁界の影響を受けて徐々に、図示右方向に変動し、抵抗値Ｒが低下し始める段階Ｈとなる。
【００２９】
次に図示右方向の外部磁界を弱めていくと、フリー磁性層及び固定磁性層の磁化が図示右方向に磁化されて抵抗値Ｒが低い状態のまま段階Ｉをたどり、外部磁界が図示左方向に加わり始めると、図示右方向に磁化されていたフリー磁性層の磁化が変動し、抵抗値Ｒが再び上昇し段階Ｊとなる。
【００３０】
さらに外部磁界を図示左側に強めていくと、図示右方向に磁化されていた固定磁性層の磁化が、図示左方向に磁化されていくことにより、抵抗値Ｒが低下し、段階Ｋになり、このようにＦ―Ｇ―Ｈ―Ｉ―Ｊ―Ｋをたどるヒステリシスループが形成される。
【００３１】
ここで反強磁性層としてα―Ｆｅ2Ｏ3を用いた場合の固定磁性層の保磁力は、図１３に示すＬの幅であり、反強磁性層をＮｉＭｎ合金膜で形成した場合に比べて固定磁性層の保磁力を大きくできることがわかる。
【００３２】
本発明の好ましい例では、固定磁性層に大きな保磁力を持たせるために、反強磁性層にα―Ｆｅ2Ｏ3を使用し、あるいは前記固定磁性層を硬磁性材料で形成し、保磁力の小さいフリー磁性層との間で保磁力差をつけることによって、磁気抵抗効果素子センサ上に形成される複数個の磁気抵抗効果素子の固定磁性層を個別に異なる方向に磁化していくことが可能となるのである。
【００３３】
本発明では、基板上に４個の磁気抵抗効果素子が形成されており、回路図で示すと図１のような回路となっている。符号１４，１５，１６，１７は各磁気抵抗効果素子の固定磁性層の磁化方向を示している。図１に示すように、直列で接続されている磁気抵抗効果素子１０と１１の固定磁性層、及び磁気抵抗効果素子１２と１３の固定磁性層の磁化方向は、それぞれ反平行（逆向き）に磁化され、また入力端子２０を介して接続された磁気抵抗効果素子１０と１２の固定磁性層の磁化は反平行に磁化された状態となっている。
【００３４】
本発明では図１に示すように各磁気抵抗効果素子の固定磁性層の磁化を、それぞれ任意の方向に向ける場合であっても、本発明のように反強磁性層にα―Ｆｅ2Ｏ3を使用すれば、個々の固定磁性層の保磁力を大きくでき、例えばコイルや導線などを使用して、前記各磁気抵抗効果素子の固定磁性層を個別に磁化していくことにより、４個の前記固定磁性層の磁化方向を適正な方向に制御することが可能になる。
【００３５】
また反強磁性層にα―Ｆｅ2Ｏ3を使用した場合、絶縁体であるため、シャント効果がなく、抵抗変化率を大きくすることができる。さらに反強磁性層にα―Ｆｅ2Ｏ3を使用した場合は、ＮｉＭｎ合金膜の場合のようにアニール（熱処理）を必要としないために、製造工程の容易化を実現できる。
【００３６】
【発明の実施の形態】
図１は本発明における磁気抵抗効果素子センサの回路図、図２は、本発明における磁気抵抗効果素子の構造を示す断面図である。
本発明における磁気抵抗効果素子センサは、ポテンショメータやエンコーダなどの角度センサあるいは速度センサなどに使用できる。
【００３７】
図１に示す符号１０，１１，１２及び１３は磁気抵抗効果素子を示しており、磁気抵抗効果素子１０と１１、及び磁気抵抗効果素子１２と１３は直列に接続されている。なお以下では、符号１０の磁気抵抗効果素子を第１の磁気抵抗効果素子、符号１１の磁気抵抗効果素子を第２の磁気抵抗効果素子、符号１２の磁気抵抗効果素子を第３の磁気抵抗効果素子、符号１３の磁気抵抗効果素子を第４の磁気抵抗効果素子と記載する。
【００３８】
図１に示すように、直接に接続された第１と第２の磁気抵抗効果素子１０，１１、及び第３と第４の磁気抵抗効果素子１２，１３の中間点には、出力端子１８，１９が設けられている。さらに、図１に示すように第１と第３の磁気抵抗効果素子１０と１２が接続され、その中間点には、入力端子２０が設けられ、また第２と第４の磁気抵抗効果素子１１と１３が接続され、その中間点にはアース端子２１が設けられている。このようにして第１と第２の磁気抵抗効果素子１０と１１とで構成される直列回路と、第３と第４の磁気抵抗効果素子１２と１３とで構成されている直列回路とが並列に接続されている。このようにして各直列回路の素子間に出力部が、直列回路の両端に出力部が形成されたものとなっている。
【００３９】
図１に示す磁気抵抗効果素子１０，１１，１２，１３上に図示された矢印方向１４，１５，１６，１７は各固定磁性層の磁化方向を示しており、直列に接続された第１の磁気抵抗効果素子１０の固定磁性層の磁化１４と第２の磁気抵抗効果素子１１の固定磁性層の磁化１５は反平行に磁化され、第４の磁気抵抗効果素子１３の固定磁性層の磁化方向１７は、第１の磁気抵抗効果素子１０の固定磁性層の磁化方向１４と同一方向に磁化されている。また第３の磁気抵抗効果素子１２の固定磁性層の磁化方向１６は、第２の磁気抵抗効果素子１１の固定磁性層の磁化方向１５と同一方向に磁化されており、これにより、直列に接続された磁気抵抗効果素子１２と１３の固定磁性層の磁化方向１６と１７は反平行に磁化された状態となっている。
【００４０】
次に本発明における磁気抵抗効果素子の構造について図２を参照して以下に説明する。
符号２２は、例えばＳｉ（シリコン）上にＡｌ2Ｏ3（アルミナ）膜が形成された基板であり、この基板２２上に反強磁性層２３が形成されている。
本発明では前記反強磁性層２３が、α―Ｆｅ2Ｏ3で形成されていることが好ましい。また反強磁性層２３上には、ＮｉＦｅ合金膜、ＣｏＦｅ合金膜、ＣｏＦｅＮｉ合金、ＮｉＣｏ合金、あるいはＣｏ膜などにより固定磁性層２４が形成されている。さらに好ましくは、前記固定磁性層２４を２層構造とし、反強磁性層２３に接する側にＮｉＦｅ合金が形成され、後述する非磁性導電層２５に接する側に、Ｃｏ膜が形成され、その上にＮｉＦｅ合金が形成されると、抵抗変化率をより向上させることが可能になる。
【００４１】
図２に示すように、前記固定磁性層２４の上には、Ｃｕ膜などで形成された非磁性導電層２５が形成されており、さらに前記非磁性導電層２５の上には、ＮｉＦｅ合金膜、ＣｏＦｅ合金膜、ＣｏＦｅＮｉ合金、ＮｉＣｏ合金、あるいはＣｏ膜などによりフリー磁性層２６が形成されている。さらに好ましくは、前記フリー磁性層２６を２層構造とし、非磁性導電層２５に接する側に、Ｃｏ膜が形成されると、抵抗変化率をより向上させることが可能になる。なお前記フリー磁性層２６の上に形成されている層２７は、例えばＴａなどで形成された保護層２７である。
【００４２】
なお図２に示すスピンバルブ膜は、下からフリー磁性層、非磁性導電層、固定磁性層、及び反強磁性層の順で積層されていてもよく、あるいは、下から、反強磁性層、固定磁性層、非磁性導電層、フリー磁性層、非磁性導電層、固定磁性層、反強磁性層の順で積層された、いわゆるデュアル型のスピンバルブ膜であってもよい。デュアル型のスピンバルブ膜で形成することにより、より抵抗変化率を高めることが可能である。
図２に示すように、α―Ｆｅ2Ｏ3で形成された反強磁性層２３と固定磁性層２４とは接して形成されており、前記固定磁性層２４は，反強磁性層２３との交換結合によって、保磁力が増大し、例えば図示右方向に磁化が固定されている。
【００４３】
これに対し、フリー磁性層２６の保磁力は、固定磁性層２４の保磁力に比べて小さく、前記フリー磁性層２６の磁化は外部磁界によって容易に変動するようになっている。
例えば、フリー磁性層２６の磁化が、外部磁界の影響を受けて、図示右方向に向けられると、固定磁性層２４の磁化方向と同一方向を向くことになり、抵抗値は最も小さくなる。逆に、フリー磁性層２６の磁化が、図示左方向に向くと、前記フリー磁性層２６の磁化と、固定磁性層２４の磁化が反平行状態になり、最も抵抗値は大きくなる。
【００４４】
前述したように本発明では、反強磁性層２３にα―Ｆｅ2Ｏ3を使用しており、これによって前記反強磁性層２３に接する固定磁性層２４の保磁力を大きくすることが可能であるが、反強磁性層２３を用いなくても、前記固定磁性層２４を硬磁性材料（永久磁石）で形成することにより、前記固定磁性層２４の保磁力を大きくすることができる。
【００４５】
本発明では、固定磁性層２４とフリー磁性層２６との保磁力差を利用して、前記固定磁性層２４の磁化方向を任意の方向に固定し、図１に示すような本発明における磁気抵抗効果素子センサの回路を形成できるようになっている。
【００４６】
図１に示す回路図上において、各磁気抵抗効果素子１０，１１，１２，１３上に示されている矢印方向は、各素子の固定磁性層２４の固定磁化方向を表しており、例えば、各磁気抵抗効果素子１０，１１，１２，１３におけるフリー磁性層の磁化がすべて図示上方向を向いているとする。入力端子（電圧印加端子）２０の電位を５Ｖに設定すると、出力端子１８からの出力（電位）は最も低く、出力端子１９からの出力は最も高くなる。各磁気抵抗効果素子１０，１１，１２，１３におけるフリー磁性層の磁化がすべて図示右方向を向いているとすると、入力端子２０の電位が５Ｖのとき、出力端子１８と出力端子１９の出力は共に２．５Ｖである。このようにして各磁気抵抗効果素子１０，１１，１２，１３のフリー磁性層の磁化がすべて同じ方向に変動していくと、出力端子１８，１９からは位相のずれた出力波形を得ることができる。
【００４７】
次に本発明における磁気抵抗効果素子センサの具体的な構造について説明する。図３は本発明における第１実施形態の磁気抵抗効果素子センサの構造を示す平面図である。
図３に示すように、基板３０上には、４個の磁気抵抗効果素子３１，３２，３３，３４が形成されている。この４個の磁気抵抗効果素子のうち、どの磁気抵抗効果素子を、第１，第２，第３，第４の磁気抵抗効果素子として設定してもよいが、本発明では特に、磁気抵抗効果素子３１を第１の磁気抵抗効果素子、磁気抵抗効果素子３２を第２の磁気抵抗効果素子、磁気抵抗効果素子３３を第３の磁気抵抗効果素子、及び磁気抵抗効果素子３４を第４の磁気抵抗効果素子として設定することが好ましい。
【００４８】
図３に示すように、第１の磁気抵抗効果素子３１と第２の磁気抵抗効果素子３２は、出力端子３７を介して、導体部３５と３６によって直列に接続されている。また、第３の磁気抵抗効果素子３３と第４の磁気抵抗効果素子３４は、導体部４０によって直列に接続されており、前記導体部４０の一端（素子３３と３４の中間）には出力端子３８が形成されている。
【００４９】
さらに第１の磁気抵抗効果素子３１と第３の磁気抵抗効果素子３３は、導体部４１によって接続され、前記導体部４１の一端には、入力端子４２が形成されている。また、第２の磁気抵抗効果素子３２と第４の磁気抵抗効果素子３４は、導体部４３によって接続されており、前記導体部４３の一端には、アース端子４４が形成されている。
【００５０】
以上のように図１の回路図と同様に、第１の磁気抵抗効果素子３１と第２の磁気抵抗効果素子３２、及び第３の磁気抵抗効果素子３３と第４の磁気抵抗効果素子３４は、それぞれ直列に接続されており、また第１の磁気抵抗効果素子３１と第３の磁気抵抗効果素子３３、及び第２の磁気抵抗効果素子３２と第４の磁気抵抗効果素子３４が、それぞれ接続されていることにより、２つの直列回路が並列に接続された状態になっている。このようにして、直列に接続された素子間に出力端子が形成され、さらに各直列回路の両端が入力部（電圧印加部）となっている。
【００５１】
本発明では、図３に示すように直列に接続される第１の磁気抵抗効果素子３１と第２の磁気抵抗効果素子３２、及び第３の磁気抵抗効果素子３３と第４の磁気抵抗効果素子３４は、それぞれ対角線上に形成されている。すなわち、第１と第４の磁気抵抗効果素子３１と３４は、基板３０の右側に列を成して並び、第２と第３の磁気抵抗効果素子３２と３３は、基板３０の左側に列を成して並んでいる。
【００５２】
各磁気抵抗効果素子上に図示されている実線の矢印方向は、固定磁性層の磁化方向を示しており、第１の磁気抵抗効果素子３１と第２の磁気抵抗効果素子３２の固定磁性層、及び第３の磁気抵抗効果素子３３と第４の磁気抵抗効果素子３４の固定磁性層は、それぞれ逆方向（反平行）に磁化された状態となっている。さらに、隣り合う第１の固定磁性層３１と第４の固定磁性層３４の固定磁性層は、共に同じ方向に磁化されており、また第２の固定磁性層３２と第３の固定磁性層３３の固定磁性層は、共に同じ方向に磁化されている。なお図３では、各素子の固定磁性層の固定磁化方向を、図１と同じ符号１４，１５，１６，１７を付して示している。
【００５３】
図４は本発明における第２実施形態の磁気抵抗効果素子センサの構造を示す平面図である。
図４に示すように、基板５０上には、４個の磁気抵抗効果素子５１，５２，５３，５４が形成されており、この４個の磁気抵抗効果素子５１，５２，５３，５４のどれを、第１，第２，第３，第４の磁気抵抗効果素子として設定してもよいが、本発明では、例えば、最も右側に形成されている磁気抵抗効果素子５１を第１の磁気抵抗効果素子、右から数えて３番目に形成されている磁気抵抗効果素子５２を第２の磁気抵抗効果素子、右から数えて２番目に形成されている磁気抵抗効果素子を第３の磁気抵抗効果素子、４番目（最も左側）の磁気抵抗効果素子を第４の磁気抵抗効果素子として設定する。
【００５４】
図４に示すように、第１の磁気抵抗効果素子５１と第２の磁気抵抗効果素子５２は、導体部５５によって直列に接続され、また前記導体部５５には、出力端子５６が形成されている。さらに第３の磁気抵抗効果素子５３と第４の磁気抵抗効果素子５４は、導体部５７によって直列に接続され、また前記導体部５７には、出力端子５８が形成されている。
【００５５】
さらに図４に示すように、第１の磁気抵抗効果素子５１と第３の磁気抵抗効果素子５３は、導体部５９によって接続され、前記導体部５９には、入力端子（電圧印加端子）６０が形成されている。また、第２の磁気抵抗効果素子５２と第４の磁気抵抗効果素子５４が導体部６１によって接続され、前記導体部６１にはアース端子６２が形成されている。
【００５６】
以上のように第１の磁気抵抗効果素子５１と第２の磁気抵抗効果素子５２、及び第３の磁気抵抗効果素子５３と第４の磁気抵抗効果素子５４は、それぞれ直列に接続されており、また第１の磁気抵抗効果素子５１と第３の磁気抵抗効果素子５３、及び第２の磁気抵抗効果素子５２と第４の磁気抵抗効果素子５４が、それぞれ接続されていることにより、２つの直列回路が並列に接続された状態になっている。このように直列に接続された素子間に出力部が形成され、また２つの直列回路の両端が入力部（電圧印加部）となっている。
【００５７】
図４に示す磁気抵抗効果素子センサでは、４個の磁気抵抗効果素子が、一直線上に形成されており、さらに前記４個の磁気抵抗効果素子の固定磁性層は、すべて同一方向（図示右方向）に磁化された状態になっている。なお各磁気抵抗効果素子上に示されている矢印は、固定磁性層の固定磁化方向を表しており、図１と同じ符号１４，１５，１６，１７を付している。
【００５８】
図３に示す磁気抵抗効果素子センサは、例えばポテンショメータに、図４に示す磁気抵抗効果素子センサは、例えばエンコーダに使用される。まずポテンショメータについて図５を参照しながら説明する。
図５に示すポテンショメータは、ケース７０の上部に、前記ケース７０を上下貫通するシャフト７１が設けられ、このシャフト７１は回転自在に取付けられている。前記シャフト７１の下端には、円盤状の磁石７２が取付られており、前記磁石７２の下方のケース７０内部に取付基板７３が設けられ、前記取付基板７３の上に、図３に示す磁気抵抗効果素子センサ７４が取付けられている。
【００５９】
図３に示す符号７５は、図５に示す磁石７２から発せられる磁界の方向を表しており、この磁界は基板３０に垂直な軸を中心として、基板３０と平行に回転する。例えば図３に示すように、前記磁界７５が図示上方向に向くと、各磁気抵抗効果素子３１，３２，３３，３４のフリー磁性層の磁化の方向（各磁気抵抗効果素子上に点線で表されている）も、前記磁界７５と同一方向、すなわち図示上方向に磁化された状態になる。
【００６０】
前記磁石７２が、図３に示す磁気抵抗効果素子センサ上で回転すると、その各磁気抵抗効果素子のフリー磁性層の磁化が変動し、このフリー磁性層の変動磁化と固定磁性層の固定磁化との関係で抵抗値が変化する。
【００６１】
図６は、図３に示す出力端子３７，３８から得られる出力の変動を示している。横軸は磁石７２の回転角度を表しており、図６に示すように、例えば出力端子３７から得られる出力波形７６と、他方の出力端子３８から得られる出力波形７７は、位相が１８０度ずれて生じている。
【００６２】
ここで、例えば図５に示す磁気抵抗効果素子センサ７４の各出力端子３７からの出力と、出力端子３８からの出力の差を取る差動回路を設けることにより、あるいは、一方の出力端子から得られる出力の位相を１８０度進めまたは遅らせる位相回路を設け、進みまたは遅れた信号と他方の端子の出力を加算回路で加算することにより、２個の磁気抵抗効果素子から成る従来の磁気抵抗効果素子センサ（図１５参照）によって得られる出力に比べ、２倍の変化率を有する出力を得ることが可能となる。
【００６３】
次に、エンコーダについて図７，８を参照しながら説明する。図７に示す符号８０は回転ドラム状の磁石８０であり、この磁石８０の外側曲面に対向して図７に示す磁気抵抗効果素子センサ８１が、基板表面を磁石８０の外周面に向けて配置される。なお、磁気抵抗効果素子センサ８１は、磁石８０の内周側に配置されてもよい。また、前記磁石８０と磁気抵抗効果素子センサ８１の距離ｔ１は、外部磁界によって、磁気抵抗効果素子センサ８１のフリー磁性層の磁化の向きが変化すれば、いくらでもよい。例えば、前記距離ｔ１は、０．５ｍｍ程度である。図７に示すように、前記回転ドラム状の磁石８０の外側曲面は、一定の間隔をおいてＮ極部とＳ極部が交互に磁化されている。
【００６４】
図８では、磁気抵抗効果素子センサ８１に形成された各磁気抵抗効果素子の固定磁性層の固定磁化と、フリー磁性層の変動磁化との関係が、磁石８０の回転によってどのように変化しているかを、わかりやすく説明するために、磁石８０の着磁面と、前記磁気抵抗効果素子センサ８１とを平面図で展開して図示している。
【００６５】
図８に示すように磁気抵抗効果素子センサ８１上に形成されている各磁気抵抗効果素子５１，５２，５３，５４の間隔は、ｔ２で形成されており、一方、磁石８０の外側曲面では、Ｎ極部とＳ極部の間隔ｔ３は、前記各磁気抵抗効果素子の間隔ｔ２の２倍になっている。
【００６６】
今、図８に示す状態にある場合、磁石８０のＡ線（Ｓ極部）と対向する位置にある磁気抵抗効果素子は、第２の磁気抵抗効果素子５２であり、また磁石８０のＢ線と対向する位置にある磁気抵抗効果素子は、第３の磁気抵抗効果素子５３である。さらに、磁石８０のＣ線（Ｎ極部）と対向する位置にある磁気抵抗効果素子は、第１の磁気抵抗効果素子５１であり、また磁石８０のＥ線と対向する位置にある磁気抵抗効果素子は、第４の磁気抵抗効果素子である。
【００６７】
図８の時点では、Ａ線及びＣ線上と対向する第２の磁気抵抗効果素子５２及び第１の磁気抵抗効果素子５１には、図示右方向あるいは図示左方向の磁界の影響はない。
一方、Ｂ線上では、Ｃ線（Ｎ極部）側からＡ線（Ｓ極部）側に磁界が発生しており、このため前記Ｂ線上に対向する位置に形成された第３の磁気抵抗効果素子５３のフリー磁性層は、図示左方向（磁気抵抗効果素子上に点線で示されている）に向く。さらに、Ｅ線上では、Ａ線（Ｓ極部）方向に磁界が発生しており、このため前記Ｅ線上に対向する位置に形成された第４の磁気抵抗効果素子５４のフリー磁性層は、図示右方向（磁気抵抗効果素子上に点線で示されている）に磁化が向く。
【００６８】
第３の磁気抵抗効果素子５３の固定磁性層の固定磁化とフリー磁性層の変動磁化との関係は、１８０度になっており、高い抵抗値を示し、一方、第４の磁気抵抗効果素子５４の固定磁性層の固定磁化とフリー磁性層の変動磁化との関係は０度になっており、低い抵抗値を示す。
【００６９】
端子６０と端子６２の間に一定の電圧を与えて、図８に示す磁石８０を例えば図示右方向に回転させると、各磁気抵抗効果素子の抵抗値は変化し、出力端子５６（図８参照）からは、図９に示す矩形状の出力波形が得られる。また出力端子５８（図８参照）からは、図９に示す出力波形に対し位相がずれた図１０に示す矩形状の出力波形が得られる。図９と図１０では、Ｔ８の時点が図８の状態のときの出力である。
【００７０】
この両出力により、磁石８０の回転周速度及び回転数を検出することができる。また図９に対する図１０の波形の位相のずれ方向が右方向であるか、左方向であるかにより、磁石８０の回転方向を知ることができる。
【００７１】
次に本発明における磁気抵抗効果素子センサの製造方法について説明する。まず、図３に示す磁気抵抗効果素子センサの製造方法について図１１を参照しながら説明する。
図１１に示すように、治具８５上に基板３０を設置し、前記基板３０上に、図２に示す膜構成から成る磁気抵抗効果素子３１，３２，３３，３４をスパッタ法や蒸着法などにより成膜する。次に、前記磁気抵抗効果素子３１（第１の磁気抵抗効果素子）と３２（第２の磁気抵抗効果素子）を直列に接続し、同様に磁気抵抗効果素子３３（第３の磁気抵抗効果素子）と３４（第４の磁気抵抗効果素子）を直列に接続する。なおこのとき、直列に接続された磁気抵抗効果素子３１と３２の間に出力端子３７を設け、磁気抵抗効果素子３３と３４との間に、出力端子３８を設けておく。さらに、磁気抵抗効果素子３１と３３を、入力端子４２を介して接続し、また、磁気抵抗効果素子３２と３４をアース端子４４を介して接続する。
【００７２】
本発明においては、直列に接続された第１の磁気抵抗効果素子３１と第２の磁気抵抗効果素子３２の固定磁性層が互いに反平行に磁化され、しかも、第１の磁気抵抗効果素子３１の固定磁性層の磁化と、第４の磁気抵抗効果素子３４の固定磁性層の磁化とが同一方向に、及び第２の磁気抵抗効果素子３２の固定磁性層の磁化と第３の磁気抵抗効果素子の３３の固定磁性層の磁化とが同一方向に磁化されていなければならない。
【００７３】
上述した磁化制御を行うために本発明では、図１１に示すように、直流電源８７から導線８８を各磁気抵抗効果素子上に配置する。ここで第１の磁気抵抗効果素子３１と第４の磁気抵抗効果素子３４上には、同一方向から電流が流れるようにし、且つ、第２の磁気抵抗効果素子３２と第３の磁気抵抗効果素子３３上には、第１の磁気抵抗効果素子３１と第４の磁気抵抗効果素子３４上に流れる電流方向と逆方向から電流が流れるように、導線８８を配置する必要性がある。
【００７４】
前記導線８８に電流を流すと、右ネジの法則により磁界が発生する。本発明では、磁気抵抗効果素子の反強磁性層をα―Ｆｅ2Ｏ3で形成しており、前記反強磁性層と固定磁性層との間で発生する交換結合が、前記磁界方向に作用し、これによって前記固定磁性層の保磁力を増幅させて前記固定磁性層の磁化をある一定方向に固定することが可能である。
【００７５】
前述したように、第１の磁気抵抗効果素子３１及び第４の磁気抵抗効果素子３４上に配置された導線８８からは、同一方向から電流が流れるので、前記第１の磁気抵抗効果素子３１及び第４の磁気抵抗効果素子３４の固定磁性層の磁化は共に同一方向に磁化される。また、第２の磁気抵抗効果素子３２及び第３の磁気抵抗効果素子３３の固定磁性層の磁化は共に同じ方向に磁化され、且つ第１の磁気抵抗効果素子３１と第４の磁気抵抗効果素子３４の固定磁性層の磁化と反平行に磁化される。
【００７６】
次に図４に示す磁気抵抗効果素子センサの製造方法について図１２を参照しながら説明する。
まず図１１の場合と同様に、治具８５上に基板５０を設置し、前記基板５０上に、４個の磁気抵抗効果素子を、スパッタ法や蒸着法などによって一直線上に成膜する。図１２に示す一番右側に形成された磁気抵抗効果素子５１を第１の磁気抵抗効果素子と、右から３番目に形成された磁気抵抗効果素子５２を第２の磁気抵抗効果素子と設定し、前記磁気抵抗効果素子５１と５２を、出力端子５６を介して直列に接続する。
【００７７】
また、図１２に示す右から２番目に形成された磁気抵抗効果素子５３を第３の磁気抵抗効果素子と、右から４番目に形成された磁気抵抗効果素子５４を第４の磁気抵抗効果素子と設定し、前記磁気抵抗効果素子５３と５４を出力端子５８を介して直列に接続する。さらに図１２に示すように、第１の磁気抵抗効果素子５１と第３の磁気抵抗効果素子５３を入力端子６０を介して接続し、また第２の磁気抵抗効果素子５２と第４の磁気抵抗効果素子５４をアース端子６２を介して接続する。
【００７８】
図１２に示すように、磁気抵抗効果素子センサの両側に、ヘルムホルツコイル９０，９１を設置し、前記ヘルムホルツコイル９０，９１に電流を流して例えば図示右方向に磁界を発生させる。これにより、各磁気抵抗効果素子５１，５２，５３，５４の固定磁性層は、すべて図示右方向に磁化された状態になる。
あるいは、前記各磁気抵抗効果素子５１，５２，５３，５４上に、一直線上に導線を配置し、前記導線に電流を流すことによって、各磁気抵抗効果素子５１，５２，５３，５４の固定磁性層をすべて同じ方向に磁化してもよい。
【００７９】
【発明の効果】
以上詳述した本発明によれば、スピンバルブ膜で形成された磁気抵抗効果素子を用いたセンサに係わり、特に固定磁性層の保磁力を増大させ、前記固定磁性層とフリー磁性層の保磁力差を利用することにより、基板上に４個の磁気抵抗効果素子を成膜した場合であっても、各磁気抵抗効果素子の固定磁性層の磁化をそれぞれ任意の方向に制御することが容易にでき、出力の増大を図ることが可能である。
【００８０】
特に本発明では、前記固定磁性層の保磁力を増大させるために、反強磁性層にα―Ｆｅ2Ｏ3を使用しており、あるいは前記固定磁性層を硬磁性材料で形成している。また反強磁性層にα―Ｆｅ2Ｏ3を使用した場合にあっては、反強磁性層にＮｉＭｎ合金などの反強磁性材料を使用した場合のように熱処理を必要としないため、製造工程を容易化でき、さらに抵抗変化率を大きくすることが可能である。
【００８１】
特に製造方法では、４個の磁気抵抗効果素子を基板上に成膜した後、各磁気抵抗効果素子上に導線、あるいはコイルなどによって、各磁気抵抗効果素子の固定磁性層を任意の方向に容易に固定することができる。
【図面の簡単な説明】
【図１】本発明における磁気抵抗効果素子センサの回路図、
【図２】磁気抵抗効果素子センサに使用される磁気抵抗効果素子（スピンバルブ膜）の膜構造を示す断面図、
【図３】本発明における磁気抵抗効果素子センサの具体的な第１の実施形態の構造を示す平面図、
【図４】本発明における磁気抵抗効果素子センサの具体的な第２の実施形態の構造を示す平面図、
【図５】本発明における磁気抵抗効果素子センサを装備したポテンショメータの部分構成図
【図６】ポテンショメータに装備された磁気抵抗効果素子センサから出力される出力波形図、
【図７】本発明における磁気抵抗効果素子センサを装備したエンコーダの部分構成図、
【図８】エンコーダに装備された磁気抵抗効果素子センサの固定磁性層の磁化とフリー磁性層の磁化との関係を表す説明図、
【図９】エンコーダに装備された磁気抵抗効果素子センサの一方の出力端子から出力される出力波形図、
【図１０】エンコーダに装備された磁気抵抗効果素子センサの他方の出力端子から出力される出力波形図、
【図１１】図３に示す磁気抵抗効果素子センサの製造の一工程を示す平面図、
【図１２】図４に示す磁気抵抗効果素子センサの製造の一工程を示す平面図、
【図１３】磁気抵抗効果素子の反強磁性層としてα―Ｆｅ2Ｏ3を使用した場合における前記磁気抵抗効果素子のヒステリシスループ、
【図１４】磁気抵抗効果素子の反強磁性層としてＮｉＭｎ合金を使用した場合における前記磁気抵抗効果素子のヒステリシスループ、
【図１５】２個の磁気抵抗効果素子を使用した従来の磁気抵抗効果素子センサの回路図、
【符号の説明】
１０、３１、５１ 第１の磁気抵抗効果素子
１１、３２、５２ 第２の磁気抵抗効果素子
１２、３３、５３ 第３の磁気抵抗効果素子
１３、３４、５４ 第４の磁気抵抗効果素子
１８、１９、３７、３８、５６、５８ 出力端子
２０、４２、６０ 入力端子、
２３ 反強磁性層
２４ 固定磁性層
２５ 非磁性導電層
２６ フリー磁性層
７２、８０ 磁石
８７ 直流電源
８８ 導線
９０、９１ ヘルムホルツコイル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetoresistive element sensor used for a position sensor such as an encoder or a potentiometer, a speed sensor, or the like, and in particular, can increase the output, and more easily manufacture the magnetoresistive element sensor. The present invention relates to a resistance effect element sensor and a manufacturing method thereof.
[0002]
[Prior art]
As the magnetoresistive effect element, there are an AMR (Anisotropic Magnetoresistance) element using an anisotropic magnetoresistive effect phenomenon and a GMR (Giant Magnetoresistance) element using a spin-dependent scattering phenomenon of conduction electrons, Among the GMR elements, a spin valve element can be cited as one having a relatively simple structure and a high resistance change rate.
The spin valve element has the simplest structure and is composed of four layers. For example, the spin valve element is formed of an antiferromagnetic layer, a pinned magnetic layer (pinned magnetic layer), a nonmagnetic conductive layer, and a free magnetic layer from the bottom.
[0003]
A Ni—Fe alloy film (permalloy) or Co is used as the pinned magnetic layer and the free magnetic layer, and a Cu film (copper) is generally used as the nonmagnetic conductive layer. As an antiferromagnetic layer, an FeMn or NiMn alloy film is conventionally used, and the magnetization of the pinned magnetic layer is fixed in a certain direction by an exchange coupling magnetic field at the interface between the antiferromagnetic layer and the pinned magnetic layer. It is like that.
The magnetization of the free magnetic layer can be reversed freely under the influence of an external magnetic field, and the resistance value changes due to fluctuations in the magnetization direction of the pinned magnetic layer and the magnetization direction of the free magnetic layer, resulting in a voltage change. Output as.
[0004]
FIG. 15 shows a circuit diagram of such a spin valve element whose resistance value changes under the influence of an external magnetic field, for example, in a potentiometer of an angle sensor.
Reference numerals 1 and 2 shown in FIG. 15 indicate magnetoresistive elements (spin valve elements). As shown in FIG. 15, two magnetoresistive elements 1 and 2 are connected in series, and an output terminal 4 is provided between the magnetoresistive elements 1 and 2. Arrows 5 and 6 shown in the magnetoresistive effect elements 1 and 2 indicate the magnetization directions of the pinned magnetic layers of the magnetoresistive effect elements 1 and 2. For example, as shown in FIG. The magnetization 5 of the fixed magnetic layer is fixed downward in the figure, and the magnetization 6 of the fixed magnetic layer of the magnetoresistive effect element 2 is fixed upward in the figure.
[0005]
When the N pole and S pole of the magnet of the potentiometer are at the positions shown in FIG. 15, the free magnetic layer of the magnetoresistive effect elements 1 and 2 is affected by the magnetic field 9 generated from the magnet, and the free magnetic layer The magnetizations 7 and 8 are oriented in the same direction as the direction of the magnetic field from the magnet.
[0006]
The magnetoresistive effect elements 1 and 2 have the smallest resistance value when the magnetization directions of the pinned magnetic layer and the free magnetic layer are directed in the same direction, and the magnetization direction is opposite, that is, as it approaches 180 degrees. The resistance value increases. In the case shown in FIG. 15, the magnetoresistive effect element 2 has a larger resistance value than the magnetoresistive effect element 1, and if the potential of the input terminal 3 is 5 V, for example, 2. An output of 5V or more can be obtained.
When the potentiometer magnet is rotated, the resistance value of each of the magnetoresistive effect elements 1 and 2 changes, but it functions as an angle sensor by obtaining an output from the difference in resistance value of the magnetoresistive effect elements 1 and 2 at this time. To do.
[0007]
[Problems to be solved by the invention]
As described above, conventionally, FeMn or NiMn alloy film has been used as the antiferromagnetic layer of the magnetoresistive effect elements 1 and 2, but this antiferromagnetic material is not subjected to annealing (heat treatment) in a magnetic field. Thus, no exchange coupling magnetic field is generated at the interface with the pinned magnetic layer. Therefore, after the magnetoresistive elements 1 and 2 are formed on the substrate, it is necessary to perform an annealing treatment in the magnetic field.
[0008]
However, when two magnetoresistive effect elements 1 and 2 are formed on a substrate and the magnetoresistive effect elements 1 and 2 are connected in a straight line, if heat treatment is performed in a magnetic field, antiferromagnetism The exchange coupling magnetic field generated at the interface between the layer and the pinned magnetic layer is generated in the same direction in both the magnetoresistive effect elements 1 and 2, and therefore the pinned magnetic layers of the magnetoresistive effect elements 1 and 2 are both in the same direction. As shown in the circuit diagram of FIG. 15, it is very difficult to direct the magnetizations 5 and 6 of the pinned magnetic layers of the magnetoresistive effect elements 1 and 2 to be antiparallel (in opposite directions) to each other. .
[0009]
If the magnetization directions 5 and 6 of the pinned magnetic layer are both fixed in the same direction, the magnetization directions 7 and 8 of the free magnetic layer that change due to the rotation of the potentiometer magnet, and the magnetization directions 5 and 5 of the pinned magnetic layer The angle with 6 is always the same in the magnetoresistive effect elements 1 and 2, and the output obtained from the output terminal 4 becomes a constant value and cannot function as an angle sensor.
[0010]
Thus, conventionally, when an antiferromagnetic layer such as a NiMn alloy that can generate an exchange coupling magnetic field at the interface with the pinned magnetic layer by heat treatment is used, a plurality of magnetoresistances are formed on the substrate. An effect element cannot be formed, and at the same time, the pinned magnetic layer of the magnetoresistive effect element cannot be magnetized in an appropriate (different) direction.
Further, when a conductive antiferromagnetic layer such as FeMn or NiMn alloy is used for the antiferromagnetic layer, the rate of change in resistance is not so high due to the shunt effect in which the detection current is diverted to the antiferromagnetic layer.
[0011]
The present invention is for solving the above-mentioned conventional problems. By optimizing the material of the antiferromagnetic layer, the formation position of the magnetoresistive effect element, and the like, the magnetoresistive effect element sensor has four magnets. Manufacturing of magnetoresistive effect element sensor capable of facilitating the manufacturing process even when the resistive effect element is formed, and capable of increasing the output, potentiometer and encoder using the same, and magnetoresistive effect sensor It aims to provide a method.
[0012]
[Means for Solving the Problems]
  In the magnetoresistive element sensor according to the present invention, four magnetoresistive elements having a pinned magnetic layer and a free magnetic layer whose magnetization direction varies under the influence of an external magnetic field are provided on a substrate. Of the two magnetoresistive elements, the pinned magnetic layer is magnetized in the same direction to form a first magnetoresistive element and a fourth magnetoresistive element, and the remaining 2 Each of the magnetoresistive effect elements has its pinned magnetic layer magnetized in the opposite direction to the pinned magnetic layers of the first and fourth magnetoresistive effect elements, so that the second magnetoresistive element and the third magnetoresistive element are magnetized. The first magnetoresistive effect element and the second magnetoresistive effect element, and the third magnetoresistive effect element and the fourth magnetoresistive effect element are output between the magnetoresistive effect elements. In the state of being connected in series. Circuit are connected in parallel, both ends of the series circuits is an input unitAnd
The first magnetoresistive effect element and the fourth magnetoresistive effect element are arranged on one side of the substrate with the magnetization directions of the pinned magnetic layers parallel to each other, and the second magnetoresistive effect element And the third magnetoresistance effect element are parallel to each other in the magnetization direction of the pinned magnetic layer, and the magnetization direction of the pinned magnetic layer of the first magnetoresistance effect element and the fourth magnetoresistance effect element is Placed on the other side of the board in the opposite directionIt is characterized by being.
[0014]
According to the present invention, the magnetoresistive effect element sensor includes the magnetoresistive effect element sensor and a magnet arranged in parallel, and the magnet is rotated about an axis perpendicular to a substrate of the magnetoresistive effect element sensor. Thus, it can be used as a potentiometer for measuring the operation of resistance change between magnetoresistive elements on the substrate.
[0015]
  Furthermore, the magnetoresistive element sensor according to the present invention is provided with four magnetoresistive elements each having a fixed magnetic layer and a free magnetic layer whose magnetization direction varies under the influence of an external magnetic field. In the magnetoresistive effect element, all the pinned magnetic layers are magnetized in the same direction and arranged in a line toward the magnetization direction of each pinned magnetic layer. Connected in series with an output section in between, the other two magnetoresistive elements are connected in series with an output section between the two elements, and the two series circuits are connected in parallel And both ends of the series circuit are inputAnd
Of the four magnetoresistive elements arranged in a row, the first and third magnetoresistive elements counted from one side are connected in series to each other, and are formed second and fourth. Magnetoresistive effect elements connected to each other in seriesIt is characterized by this.
[0017]
In the present invention, the magnetoresistive element sensor is disposed to face a rotating drum in which N poles and S poles are alternately formed in a rotation direction, and the magnetoresistive element sensor is rotated by rotating the rotating drum. It can be used as an encoder for measuring a resistance change between magnetoresistive effect elements formed in the effect element sensor.
In the present invention, it is preferable that the interval between the N pole and the S pole is formed to be twice the interval between the magnetoresistive elements arranged in a line on the magnetoresistive element sensor.
[0018]
By the way, in the present invention, the coercive force of the pinned magnetic layer of the magnetoresistive effect element needs to be larger than the coercive force of the free magnetic layer. For example, in one layer in contact with the pinned magnetic layer, An antiferromagnetic layer is formed, and the antiferromagnetic layer includes α-Fe2OThreeIt is preferable that it is formed. Alternatively, the pinned magnetic layer may be formed of a hard magnetic material.
[0019]
The present invention also relates to a method of manufacturing a magnetoresistive element sensor,
Four magnetoresistive elements having a pinned magnetic layer and a free magnetic layer whose magnetization varies under the influence of an external magnetic field are formed on a substrate. At this time, the first magnetoresistive effect is formed on one side of the substrate. Arranging the element and the second magnetoresistive element side by side, and arranging the third magnetoresistive element and the fourth magnetoresistive element side by side on the other side of the substrate;
Connecting the first magnetoresistive element and the second magnetoresistive element, and the third magnetoresistive element and the fourth magnetoresistive element in series so as to have an output portion in the middle of the element When,
Connecting the two series circuits in parallel and forming an input at both ends of the series circuit;
Conductive wires are arranged on the first magnetoresistive element and the fourth magnetoresistive element, and on the second magnetoresistive element and the third magnetoresistive element, respectively, and currents flow through the two conductive lines. Are reversed, the magnetizations of the pinned magnetic layers of the first and fourth magnetoresistive elements, and the pinned magnetic layers of the second and third magnetoresistive elements. Fixing the magnetization in the opposite direction;
It is characterized by having.
[0020]
Furthermore, the present invention provides a method for manufacturing a magnetoresistive element sensor,
Forming a magnetoresistive effect element having a fixed magnetic layer and a free magnetic layer whose magnetization fluctuates under the influence of an external magnetic field in a row on a substrate;
A step of connecting the first and third magnetoresistive elements, counting from one side, in series by forming an output portion between the two elements;
Connecting the second and fourth magnetoresistive elements in series by forming an output portion between the two elements;
Connecting the two series circuits in parallel and forming input portions at both ends of the series circuit;
A magnetic field directed to the arrangement direction is applied to the four magnetoresistive elements, and the fixed magnetic layers of all the magnetoresistive elements are magnetized in the same direction.
[0021]
In the present invention, a lead wire is disposed on each of the four magnetoresistive effect elements, and a current is passed through the lead wires to magnetize the fixed magnetic layers of the four magnetoresistive effect elements in the same direction. Is preferred.
[0022]
Furthermore, in the present invention, one layer in contact with the fixed magnetic layer of the magnetoresistive element is formed by α-Fe.2OThreePreferably, the pinned magnetic layer of the magnetoresistive element may be formed of a hard magnetic material made of CoPt, CoPtCr alloy, or the like.
[0023]
The FeMn and NiMn alloy films conventionally used as the antiferromagnetic layer of the magnetoresistive effect element do not generate an exchange coupling magnetic field at the interface with the fixed magnetic layer in the film formation stage, and are annealed in the magnetic field after the film formation (heat treatment). ), An exchange coupling magnetic field is generated at the interface with the fixed magnetic layer, and the magnetization of the fixed magnetic layer is fixed in a certain direction.
[0024]
FIG. 14 shows an RH curve when the antiferromagnetic layer is formed of a NiMn alloy film. The horizontal axis indicates the external magnetic field, and the external magnetic field is applied in the left direction in the figure on the left side of the origin, and the external magnetic field is applied in the right direction in the figure on the right side of the origin.
[0025]
First, in the portion of stage A shown in FIG. 14, the resistance value R is almost 0. This is because both the magnetization of the fixed magnetic layer and the free magnetic layer of the magnetoresistive effect element are magnetized in the left direction. Because. The resistance value R begins to increase in the vicinity of the origin where the external magnetic field in the left direction in the figure weakens and the external magnetic field starts to be applied in the right direction in the figure. In stage B, the magnetization of the free magnetic layer that has been magnetized in the left direction is affected by the external magnetic field, and the magnetization direction of the free magnetic layer fluctuates, resulting in an angular difference from the magnetization direction of the pinned magnetic layer. As a result, the resistance value R increases rapidly.
[0026]
At stage C, the resistance value R starts to decrease. This is because the magnetization of the pinned magnetic layer fixed in the left direction in the figure is affected by the external magnetic field acting in the right direction in the figure and gradually increases in the right direction in the figure. At the point of stage C, the angle difference in the magnetization direction gradually decreases with the free magnetic layer that is completely magnetized in the right direction in the figure, and the resistance value R starts to decrease.
[0027]
At stage D, the external magnetic field in the right direction in the figure is weakened, so that the magnetization of the pinned magnetic layer magnetized in the right direction in the figure is tilted in the magnetization direction by the exchange coupling magnetic field with the antiferromagnetic layer, that is, in the left direction in the figure. First, draw a hysteresis loop that follows stage B and stage A. The width E shown in FIG. 14 represents the coercive force of the pinned magnetic layer.
On the other hand, in the present invention, α-Fe is used as the antiferromagnetic layer of the magnetoresistive element.2OThree(Α-fematite) is used. Antiferromagnetic layer is α-Fe2OThreeFIG. 13 shows an RH curve when formed with a film. The horizontal axis indicates the external magnetic field, and the external magnetic field is applied in the left direction in the figure on the left side of the origin, and the external magnetic field is applied in the right direction in the figure on the right side of the origin.
[0028]
First, in stage F shown in FIG. 13, the magnetization directions of the pinned magnetic layer and the free magnetic layer of the magnetoresistive effect element layer are both directed to the left in the figure, and the resistance value R is very low.
The external magnetic field in the left direction in the figure starts to weaken, and the resistance value R starts to increase as the magnetization of the free magnetic layer fluctuates under the influence of the external magnetic field near the origin where the external magnetic field moves in the right direction in the figure. , Stage G. When the external magnetic field is further strengthened in the right direction in the figure, the magnetization of the pinned magnetic layer magnetized in the left direction in the figure gradually changes in the right direction in the figure due to the influence of the external magnetic field, and the resistance value R decreases. It becomes stage H to start.
[0029]
Next, when the external magnetic field in the right direction in the figure is weakened, the magnetization of the free magnetic layer and the pinned magnetic layer is magnetized in the right direction in the figure and the resistance R is kept low, and the step I is followed. As a result, the magnetization of the free magnetic layer magnetized in the right direction in the figure fluctuates, and the resistance value R rises again to become stage J.
[0030]
When the external magnetic field is further strengthened on the left side in the figure, the magnetization of the pinned magnetic layer that has been magnetized in the right direction in the figure is magnetized in the left direction in the figure, so that the resistance value R decreases and the stage K is reached. Thus, a hysteresis loop that follows F-G-H-I-J-K is formed.
[0031]
Here, α-Fe is used as the antiferromagnetic layer.2OThreeThe coercive force of the pinned magnetic layer when using is the width of L shown in FIG. 13, and it can be seen that the coercive force of the pinned magnetic layer can be increased compared to the case where the antiferromagnetic layer is formed of a NiMn alloy film.
[0032]
In a preferred example of the present invention, α-Fe is added to the antiferromagnetic layer in order to give the pinned magnetic layer a large coercive force.2OThreeOr a plurality of magnets formed on the magnetoresistive element sensor by forming the pinned magnetic layer of a hard magnetic material and making a coercive force difference with a free magnetic layer having a small coercive force. This makes it possible to individually magnetize the pinned magnetic layer of the resistance effect element in different directions.
[0033]
In the present invention, four magnetoresistive elements are formed on a substrate, and a circuit diagram as shown in FIG. 1 is obtained. Reference numerals 14, 15, 16, and 17 indicate the magnetization directions of the pinned magnetic layers of the magnetoresistive elements. As shown in FIG. 1, the magnetization directions of the pinned magnetic layers of the magnetoresistive effect elements 10 and 11 and the pinned magnetic layers of the magnetoresistive effect elements 12 and 13 connected in series are antiparallel (reverse), respectively. The magnetizations of the pinned magnetic layers of the magnetoresistive effect elements 10 and 12 that are magnetized and connected via the input terminal 20 are magnetized antiparallel.
[0034]
In the present invention, as shown in FIG. 1, even if the magnetization of the pinned magnetic layer of each magnetoresistive element is directed in an arbitrary direction, α-Fe is applied to the antiferromagnetic layer as in the present invention.2OThreeCan be used to increase the coercive force of each pinned magnetic layer. For example, by using a coil or a conductive wire, the pinned magnetic layer of each magnetoresistive element is individually magnetized. It becomes possible to control the magnetization direction of the pinned magnetic layer to an appropriate direction.
[0035]
In addition, α-Fe is added to the antiferromagnetic layer.2OThreeWhen used, since it is an insulator, there is no shunt effect and the resistance change rate can be increased. Furthermore, α-Fe is added to the antiferromagnetic layer.2OThreeWhen Ni is used, annealing (heat treatment) is not required as in the case of the NiMn alloy film, so that the manufacturing process can be facilitated.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a circuit diagram of a magnetoresistive effect element sensor according to the present invention, and FIG. 2 is a cross-sectional view showing the structure of the magnetoresistive effect element according to the present invention.
The magnetoresistive element sensor in the present invention can be used for an angle sensor or a speed sensor such as a potentiometer or an encoder.
[0037]
Reference numerals 10, 11, 12 and 13 shown in FIG. 1 denote magnetoresistive elements, and the magnetoresistive elements 10 and 11 and the magnetoresistive elements 12 and 13 are connected in series. In the following description, the magnetoresistive effect element denoted by reference numeral 10 is the first magnetoresistive effect element, the magnetoresistive effect element denoted by reference numeral 11 is the second magnetoresistive effect element, and the magnetoresistive effect element denoted by reference numeral 12 is the third magnetoresistive effect element. The element, the magnetoresistive effect element of the code | symbol 13 is described as a 4th magnetoresistive effect element.
[0038]
As shown in FIG. 1, output terminals 18, 11 are directly connected to the intermediate points of the first and second magnetoresistive elements 10, 11 and the third and fourth magnetoresistive elements 12, 13. 19 is provided. Further, as shown in FIG. 1, the first and third magnetoresistive elements 10 and 12 are connected, an input terminal 20 is provided at an intermediate point thereof, and the second and fourth magnetoresistive elements 11 are provided. And 13 are connected, and a ground terminal 21 is provided at an intermediate point thereof. In this way, the series circuit composed of the first and second magnetoresistive elements 10 and 11 and the series circuit composed of the third and fourth magnetoresistive elements 12 and 13 are parallel. It is connected to the. In this way, output units are formed between the elements of each series circuit, and output units are formed at both ends of the series circuit.
[0039]
The arrow directions 14, 15, 16, and 17 illustrated on the magnetoresistive effect elements 10, 11, 12, and 13 shown in FIG. 1 indicate the magnetization directions of the respective fixed magnetic layers, and the first directions connected in series. The magnetization 14 of the pinned magnetic layer of the magnetoresistive effect element 10 and the magnetization 15 of the pinned magnetic layer of the second magnetoresistive effect element 11 are magnetized antiparallel, and the magnetization direction of the pinned magnetic layer of the fourth magnetoresistive effect element 13 17 is magnetized in the same direction as the magnetization direction 14 of the pinned magnetic layer of the first magnetoresistance effect element 10. Further, the magnetization direction 16 of the pinned magnetic layer of the third magnetoresistive effect element 12 is magnetized in the same direction as the magnetization direction 15 of the pinned magnetic layer of the second magnetoresistive effect element 11, thereby connecting in series. The magnetization directions 16 and 17 of the pinned magnetic layers of the magnetoresistive effect elements 12 and 13 are magnetized antiparallel.
[0040]
Next, the structure of the magnetoresistive effect element according to the present invention will be described below with reference to FIG.
Reference numeral 22 represents, for example, Al on Si (silicon).2OThreeA substrate on which an (alumina) film is formed, and an antiferromagnetic layer 23 is formed on the substrate 22.
In the present invention, the antiferromagnetic layer 23 is α-Fe.2OThreeIt is preferable that it is formed. On the antiferromagnetic layer 23, a pinned magnetic layer 24 is formed of a NiFe alloy film, a CoFe alloy film, a CoFeNi alloy, a NiCo alloy, a Co film, or the like. More preferably, the pinned magnetic layer 24 has a two-layer structure, a NiFe alloy is formed on the side in contact with the antiferromagnetic layer 23, and a Co film is formed on the side in contact with the nonmagnetic conductive layer 25 described later. If a NiFe alloy is formed on the surface, the resistance change rate can be further improved.
[0041]
As shown in FIG. 2, a nonmagnetic conductive layer 25 formed of a Cu film or the like is formed on the pinned magnetic layer 24, and a NiFe alloy film is further formed on the nonmagnetic conductive layer 25. The free magnetic layer 26 is formed of a CoFe alloy film, a CoFeNi alloy, a NiCo alloy, a Co film, or the like. More preferably, when the free magnetic layer 26 has a two-layer structure and a Co film is formed on the side in contact with the nonmagnetic conductive layer 25, the resistance change rate can be further improved. The layer 27 formed on the free magnetic layer 26 is a protective layer 27 formed of Ta or the like, for example.
[0042]
The spin valve film shown in FIG. 2 may be laminated in the order of a free magnetic layer, a nonmagnetic conductive layer, a pinned magnetic layer, and an antiferromagnetic layer from the bottom, or from the bottom, an antiferromagnetic layer, It may be a so-called dual type spin valve film in which a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer, a nonmagnetic conductive layer, a pinned magnetic layer, and an antiferromagnetic layer are laminated in this order. By forming the dual type spin valve film, it is possible to further increase the rate of resistance change.
As shown in FIG. 2, α-Fe2OThreeThe antiferromagnetic layer 23 and the pinned magnetic layer 24 are formed in contact with each other, and the pinned magnetic layer 24 has an increased coercive force due to exchange coupling with the antiferromagnetic layer 23. Magnetization is fixed in the direction.
[0043]
On the other hand, the coercive force of the free magnetic layer 26 is smaller than the coercive force of the pinned magnetic layer 24, and the magnetization of the free magnetic layer 26 is easily changed by an external magnetic field.
For example, when the magnetization of the free magnetic layer 26 is directed to the right in the figure under the influence of the external magnetic field, the magnetization direction is the same as the magnetization direction of the pinned magnetic layer 24, and the resistance value is minimized. On the other hand, when the magnetization of the free magnetic layer 26 is directed to the left in the figure, the magnetization of the free magnetic layer 26 and the magnetization of the pinned magnetic layer 24 are in an antiparallel state, and the resistance value is maximized.
[0044]
As described above, in the present invention, the antiferromagnetic layer 23 has α-Fe.2OThreeThus, the coercive force of the pinned magnetic layer 24 in contact with the antiferromagnetic layer 23 can be increased, but the pinned magnetic layer 24 can be formed without using the antiferromagnetic layer 23. By forming it with a hard magnetic material (permanent magnet), the coercive force of the pinned magnetic layer 24 can be increased.
[0045]
In the present invention, the magnetization direction of the pinned magnetic layer 24 is fixed in an arbitrary direction by utilizing the coercive force difference between the pinned magnetic layer 24 and the free magnetic layer 26, and the magnetoresistive in the present invention as shown in FIG. An effect element sensor circuit can be formed.
[0046]
In the circuit diagram shown in FIG. 1, the arrow direction shown on each magnetoresistive effect element 10, 11, 12, 13 represents the fixed magnetization direction of the fixed magnetic layer 24 of each element. It is assumed that the magnetizations of the free magnetic layers in the magnetoresistive elements 10, 11, 12, and 13 are all directed upward in the drawing. When the potential of the input terminal (voltage application terminal) 20 is set to 5 V, the output (potential) from the output terminal 18 is the lowest and the output from the output terminal 19 is the highest. Assuming that the magnetizations of the free magnetic layers in the magnetoresistive elements 10, 11, 12, and 13 all turn to the right in the figure, when the potential of the input terminal 20 is 5 V, the outputs of the output terminal 18 and the output terminal 19 are Both are 2.5V. In this way, when the magnetizations of the free magnetic layers of the magnetoresistive elements 10, 11, 12, and 13 all change in the same direction, an output waveform having a phase shift can be obtained from the output terminals 18 and 19. it can.
[0047]
Next, a specific structure of the magnetoresistive effect element sensor according to the present invention will be described. FIG. 3 is a plan view showing the structure of the magnetoresistive effect element sensor according to the first embodiment of the present invention.
As shown in FIG. 3, four magnetoresistive elements 31, 32, 33, and 34 are formed on the substrate 30. Of these four magnetoresistive elements, any one of the magnetoresistive elements may be set as the first, second, third and fourth magnetoresistive elements. The element 31 is a first magnetoresistive element, the magnetoresistive element 32 is a second magnetoresistive element, the magnetoresistive element 33 is a third magnetoresistive element, and the magnetoresistive element 34 is a fourth magnetic element. It is preferable to set as a resistance effect element.
[0048]
As shown in FIG. 3, the first magnetoresistive element 31 and the second magnetoresistive element 32 are connected in series by conductor portions 35 and 36 via an output terminal 37. The third magnetoresistive effect element 33 and the fourth magnetoresistive effect element 34 are connected in series by a conductor portion 40, and an output terminal is provided at one end of the conductor portion 40 (in the middle of the elements 33 and 34). 38 is formed.
[0049]
Further, the first magnetoresistive element 31 and the third magnetoresistive element 33 are connected by a conductor portion 41, and an input terminal 42 is formed at one end of the conductor portion 41. The second magnetoresistive effect element 32 and the fourth magnetoresistive effect element 34 are connected by a conductor portion 43, and a ground terminal 44 is formed at one end of the conductor portion 43.
[0050]
As described above, the first magnetoresistive effect element 31 and the second magnetoresistive effect element 32, and the third magnetoresistive effect element 33 and the fourth magnetoresistive effect element 34 are similar to the circuit diagram of FIG. The first magnetoresistive effect element 31 and the third magnetoresistive effect element 33, and the second magnetoresistive effect element 32 and the fourth magnetoresistive effect element 34 are respectively connected in series. As a result, two series circuits are connected in parallel. Thus, an output terminal is formed between the elements connected in series, and both ends of each series circuit are input parts (voltage application parts).
[0051]
In the present invention, as shown in FIG. 3, the first magnetoresistive effect element 31 and the second magnetoresistive effect element 32, and the third magnetoresistive effect element 33 and the fourth magnetoresistive effect element connected in series. Each 34 is formed on a diagonal line. That is, the first and fourth magnetoresistive elements 31 and 34 are arranged in a row on the right side of the substrate 30, and the second and third magnetoresistive elements 32 and 33 are arranged on the left side of the substrate 30. Are lined up.
[0052]
The solid arrow direction shown on each magnetoresistive effect element indicates the magnetization direction of the pinned magnetic layer. The pinned magnetic layers of the first magnetoresistive effect element 31 and the second magnetoresistive effect element 32, The fixed magnetic layers of the third magnetoresistive element 33 and the fourth magnetoresistive element 34 are magnetized in opposite directions (antiparallel). Further, the pinned magnetic layers of the adjacent first pinned magnetic layer 31 and the fourth pinned magnetic layer 34 are both magnetized in the same direction, and the second pinned magnetic layer 32 and the third pinned magnetic layer 33 are also magnetized. Both of the fixed magnetic layers are magnetized in the same direction. In FIG. 3, the fixed magnetization direction of the fixed magnetic layer of each element is indicated by the same reference numerals 14, 15, 16, and 17 as in FIG.
[0053]
FIG. 4 is a plan view showing the structure of the magnetoresistive effect element sensor according to the second embodiment of the present invention.
As shown in FIG. 4, four magnetoresistive elements 51, 52, 53, and 54 are formed on the substrate 50, and any of the four magnetoresistive elements 51, 52, 53, and 54 is formed. May be set as the first, second, third, and fourth magnetoresistive elements, but in the present invention, for example, the magnetoresistive element 51 formed on the rightmost side is the first magnetoresistive element. The magnetoresistive effect element 52 formed third from the right is the second magnetoresistive effect element, and the second magnetoresistive effect element counted from the right is the third magnetoresistive effect. The fourth (leftmost) magnetoresistive effect element is set as the fourth magnetoresistive effect element.
[0054]
As shown in FIG. 4, the first magnetoresistive effect element 51 and the second magnetoresistive effect element 52 are connected in series by a conductor portion 55, and an output terminal 56 is formed on the conductor portion 55. Yes. Further, the third magnetoresistive effect element 53 and the fourth magnetoresistive effect element 54 are connected in series by a conductor portion 57, and an output terminal 58 is formed on the conductor portion 57.
[0055]
Further, as shown in FIG. 4, the first magnetoresistive effect element 51 and the third magnetoresistive effect element 53 are connected by a conductor portion 59, and an input terminal (voltage application terminal) 60 is connected to the conductor portion 59. Is formed. The second magnetoresistive effect element 52 and the fourth magnetoresistive effect element 54 are connected by a conductor portion 61, and a ground terminal 62 is formed on the conductor portion 61.
[0056]
As described above, the first magnetoresistive effect element 51 and the second magnetoresistive effect element 52, and the third magnetoresistive effect element 53 and the fourth magnetoresistive effect element 54 are respectively connected in series. In addition, since the first magnetoresistive element 51 and the third magnetoresistive element 53, and the second and fourth magnetoresistive elements 52 and 54 are connected to each other, two series are connected. The circuit is connected in parallel. Thus, an output part is formed between the elements connected in series, and both ends of the two series circuits are input parts (voltage application parts).
[0057]
In the magnetoresistive effect element sensor shown in FIG. 4, four magnetoresistive effect elements are formed in a straight line, and the fixed magnetic layers of the four magnetoresistive effect elements are all in the same direction (the right direction in the figure). ) Is magnetized. In addition, the arrow shown on each magnetoresistive effect element represents the fixed magnetization direction of a fixed magnetic layer, and has attached | subjected the code | symbol 14, 15, 16, 17 same as FIG.
[0058]
The magnetoresistive effect element sensor shown in FIG. 3 is used for, for example, a potentiometer, and the magnetoresistive effect element sensor shown in FIG. 4 is used for, for example, an encoder. First, the potentiometer will be described with reference to FIG.
The potentiometer shown in FIG. 5 is provided with a shaft 71 vertically passing through the case 70 at the top of the case 70, and the shaft 71 is rotatably attached. A disc-shaped magnet 72 is attached to the lower end of the shaft 71, and a mounting board 73 is provided inside the case 70 below the magnet 72. The magnetoresistor shown in FIG. An effect element sensor 74 is attached.
[0059]
3 represents the direction of the magnetic field emitted from the magnet 72 shown in FIG. 5, and this magnetic field rotates in parallel with the substrate 30 about an axis perpendicular to the substrate 30. For example, as shown in FIG. 3, when the magnetic field 75 is directed upward in the figure, the magnetization direction of the free magnetic layer of each magnetoresistive effect element 31, 32, 33, 34 (represented by a dotted line on each magnetoresistive effect element). Is also magnetized in the same direction as the magnetic field 75, that is, in the upward direction in the figure.
[0060]
When the magnet 72 rotates on the magnetoresistive effect element sensor shown in FIG. 3, the magnetization of the free magnetic layer of each magnetoresistive effect element fluctuates, and the fluctuation magnetization of the free magnetic layer and the fixed magnetization of the fixed magnetic layer The resistance value changes due to
[0061]
FIG. 6 shows fluctuations in the output obtained from the output terminals 37 and 38 shown in FIG. The horizontal axis represents the rotation angle of the magnet 72. As shown in FIG. 6, for example, the output waveform 76 obtained from the output terminal 37 and the output waveform 77 obtained from the other output terminal 38 are out of phase by 180 degrees. Has occurred.
[0062]
Here, for example, by providing a differential circuit that takes a difference between the output from each output terminal 37 of the magnetoresistive effect element sensor 74 shown in FIG. 5 and the output from the output terminal 38, or obtained from one output terminal. A conventional magnetoresistive effect element comprising two magnetoresistive effect elements is provided by providing a phase circuit that advances or delays the phase of the output to be advanced by 180 degrees, and adding the advanced or delayed signal and the output of the other terminal by an adder circuit Compared to the output obtained by the sensor (see FIG. 15), it is possible to obtain an output having a twice rate of change.
[0063]
Next, the encoder will be described with reference to FIGS. Reference numeral 80 shown in FIG. 7 is a rotating drum-shaped magnet 80, and the magnetoresistive element sensor 81 shown in FIG. 7 is arranged so that the surface of the substrate faces the outer peripheral surface of the magnet 80. Is done. The magnetoresistive element sensor 81 may be arranged on the inner peripheral side of the magnet 80. Further, the distance t1 between the magnet 80 and the magnetoresistive element sensor 81 may be any as long as the magnetization direction of the free magnetic layer of the magnetoresistive element sensor 81 is changed by an external magnetic field. For example, the distance t1 is about 0.5 mm. As shown in FIG. 7, on the outer curved surface of the rotating drum-shaped magnet 80, the N pole portion and the S pole portion are alternately magnetized at a constant interval.
[0064]
In FIG. 8, how the relationship between the fixed magnetization of the fixed magnetic layer of each magnetoresistive effect element formed in the magnetoresistive effect element sensor 81 and the variable magnetization of the free magnetic layer is changed by the rotation of the magnet 80. In order to easily explain whether or not the magnetized surface of the magnet 80 and the magnetoresistive element sensor 81 are developed in a plan view.
[0065]
As shown in FIG. 8, the interval between the magnetoresistive elements 51, 52, 53, and 54 formed on the magnetoresistive element sensor 81 is formed at t2, while the outer curved surface of the magnet 80 is An interval t3 between the N pole portion and the S pole portion is twice the interval t2 between the magnetoresistive elements.
[0066]
In the state shown in FIG. 8, the magnetoresistive effect element at the position facing the A line (S pole portion) of the magnet 80 is the second magnetoresistive effect element 52, and the B line of the magnet 80. The third magnetoresistive element 53 is the magnetoresistive element at the position opposite to. Further, the magnetoresistive effect element located at the position facing the C line (N pole portion) of the magnet 80 is the first magnetoresistive effect element 51, and the magnetoresistive effect located at the position facing the E line of the magnet 80. The element is a fourth magnetoresistance effect element.
[0067]
At the time of FIG. 8, the second magnetoresistive effect element 52 and the first magnetoresistive effect element 51 facing the A line and the C line are not affected by the magnetic field in the right direction or the left direction.
On the other hand, on the B line, a magnetic field is generated from the C line (N pole part) side to the A line (S pole part) side. Therefore, the third magnetoresistive effect formed at a position facing the B line. The free magnetic layer of the element 53 faces in the left direction (shown by a dotted line on the magnetoresistive element). Further, on the E line, a magnetic field is generated in the direction of the A line (S pole portion). Therefore, the free magnetic layer of the fourth magnetoresistive effect element 54 formed at a position facing the E line is shown in the figure. Magnetization is directed to the right (indicated by a dotted line on the magnetoresistive element).
[0068]
The relationship between the fixed magnetization of the fixed magnetic layer of the third magnetoresistive effect element 53 and the variable magnetization of the free magnetic layer is 180 degrees, showing a high resistance value, while the fourth magnetoresistive effect element 54 is shown. The relationship between the fixed magnetization of the fixed magnetic layer and the variable magnetization of the free magnetic layer is 0 degree, indicating a low resistance value.
[0069]
When a constant voltage is applied between the terminal 60 and the terminal 62 and the magnet 80 shown in FIG. 8 is rotated to the right in the figure, for example, the resistance value of each magnetoresistive element changes, and the output terminal 56 (see FIG. 8). From FIG. 9, the rectangular output waveform shown in FIG. 9 is obtained. Further, from the output terminal 58 (see FIG. 8), a rectangular output waveform shown in FIG. 10 having a phase shifted from the output waveform shown in FIG. 9 is obtained. 9 and 10, the output at the time point T8 is the state shown in FIG.
[0070]
With these two outputs, the rotational peripheral speed and the rotational speed of the magnet 80 can be detected. Further, the rotation direction of the magnet 80 can be known by determining whether the phase shift direction of the waveform of FIG. 10 with respect to FIG. 9 is the right direction or the left direction.
[0071]
Next, the manufacturing method of the magnetoresistive effect element sensor in this invention is demonstrated. First, a method of manufacturing the magnetoresistive effect element sensor shown in FIG. 3 will be described with reference to FIG.
As shown in FIG. 11, a substrate 30 is placed on a jig 85, and on the substrate 30, magnetoresistive elements 31, 32, 33, and 34 having the film configuration shown in FIG. The film is formed by Next, the magnetoresistive effect element 31 (first magnetoresistive effect element) and 32 (second magnetoresistive effect element) are connected in series, and similarly, the magnetoresistive effect element 33 (third magnetoresistive effect element). ) And 34 (fourth magnetoresistance effect element) are connected in series. At this time, an output terminal 37 is provided between the magnetoresistive effect elements 31 and 32 connected in series, and an output terminal 38 is provided between the magnetoresistive effect elements 33 and 34. Further, the magnetoresistive effect elements 31 and 33 are connected via the input terminal 42, and the magnetoresistive effect elements 32 and 34 are connected via the ground terminal 44.
[0072]
In the present invention, the fixed magnetic layers of the first magnetoresistive effect element 31 and the second magnetoresistive effect element 32 connected in series are magnetized antiparallel to each other, and the first magnetoresistive effect element 31 has The magnetization of the pinned magnetic layer and the magnetization of the pinned magnetic layer of the fourth magnetoresistive effect element 34 are in the same direction, and the magnetization of the pinned magnetic layer of the second magnetoresistive effect element 32 and the third magnetoresistive effect element The magnetization of the 33 pinned magnetic layers must be magnetized in the same direction.
[0073]
In order to perform the above-described magnetization control, in the present invention, as shown in FIG. 11, a conducting wire 88 is arranged on each magnetoresistive element from a DC power supply 87. Here, a current flows from the same direction on the first magnetoresistive element 31 and the fourth magnetoresistive element 34, and the second magnetoresistive element 32 and the third magnetoresistive element It is necessary to arrange the conductor 88 on 33 so that the current flows in the direction opposite to the direction of the current flowing on the first magnetoresistive element 31 and the fourth magnetoresistive element 34.
[0074]
When a current is passed through the conductor 88, a magnetic field is generated according to the right-handed screw law. In the present invention, the antiferromagnetic layer of the magnetoresistive element is formed by α-Fe.2OThreeThe exchange coupling generated between the antiferromagnetic layer and the pinned magnetic layer acts in the magnetic field direction, thereby amplifying the coercive force of the pinned magnetic layer and It is possible to fix the magnetization in a certain direction.
[0075]
As described above, since the current flows from the same direction from the conductive wire 88 arranged on the first magnetoresistive element 31 and the fourth magnetoresistive element 34, the first magnetoresistive element 31 and Both the magnetizations of the pinned magnetic layers of the fourth magnetoresistive element 34 are magnetized in the same direction. The magnetizations of the pinned magnetic layers of the second magnetoresistive element 32 and the third magnetoresistive element 33 are both magnetized in the same direction, and the first magnetoresistive element 31 and the fourth magnetoresistive element It is magnetized antiparallel to the magnetization of the 34 pinned magnetic layer.
[0076]
Next, a method of manufacturing the magnetoresistive effect element sensor shown in FIG. 4 will be described with reference to FIG.
First, as in the case of FIG. 11, the substrate 50 is set on the jig 85, and four magnetoresistive elements are formed on the substrate 50 in a straight line by a sputtering method, a vapor deposition method, or the like. The magnetoresistive effect element 51 formed on the rightmost side shown in FIG. 12 is set as the first magnetoresistive effect element, and the magnetoresistive effect element 52 formed third from the right is set as the second magnetoresistive effect element. The magnetoresistance effect elements 51 and 52 are connected in series via an output terminal 56.
[0077]
Also, the magnetoresistive effect element 53 formed second from the right shown in FIG. 12 is the third magnetoresistive effect element, and the magnetoresistive effect element 54 formed fourth from the right is the fourth magnetoresistive effect element. The magnetoresistive effect elements 53 and 54 are connected in series via the output terminal 58. Further, as shown in FIG. 12, the first magnetoresistive effect element 51 and the third magnetoresistive effect element 53 are connected via the input terminal 60, and the second magnetoresistive effect element 52 and the fourth magnetoresistive effect element are connected. The effect element 54 is connected via the ground terminal 62.
[0078]
As shown in FIG. 12, Helmholtz coils 90 and 91 are installed on both sides of the magnetoresistive element sensor, and a current is passed through the Helmholtz coils 90 and 91 to generate a magnetic field in the right direction in the figure, for example. Thereby, all the pinned magnetic layers of the magnetoresistive effect elements 51, 52, 53, and 54 are magnetized in the right direction in the drawing.
Alternatively, a fixed wire of each of the magnetoresistive effect elements 51, 52, 53, and 54 is provided by arranging a conducting wire on a straight line on each of the magnetoresistive effect elements 51, 52, 53, and 54 and causing a current to flow through the conducting wire. All layers may be magnetized in the same direction.
[0079]
【The invention's effect】
According to the present invention described in detail above, the present invention relates to a sensor using a magnetoresistive effect element formed of a spin valve film, and particularly increases the coercive force of the pinned magnetic layer, and the coercive force of the pinned magnetic layer and the free magnetic layer. By utilizing the difference, it is easy to control the magnetization of the fixed magnetic layer of each magnetoresistive element in any direction even when four magnetoresistive elements are formed on the substrate. It is possible to increase the output.
[0080]
In particular, in the present invention, in order to increase the coercive force of the pinned magnetic layer, the antiferromagnetic layer has α-Fe.2OThreeOr the pinned magnetic layer is made of a hard magnetic material. In addition, α-Fe is added to the antiferromagnetic layer.2OThreeIs used, the heat treatment is not required as in the case of using an antiferromagnetic material such as a NiMn alloy for the antiferromagnetic layer, so that the manufacturing process can be simplified and the resistance change rate is increased. It is possible.
[0081]
In particular, in the manufacturing method, after four magnetoresistive effect elements are formed on a substrate, the fixed magnetic layer of each magnetoresistive effect element can be easily arranged in any direction by a conductor or a coil on each magnetoresistive effect element. Can be fixed to.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a magnetoresistive element sensor according to the present invention;
FIG. 2 is a cross-sectional view showing a film structure of a magnetoresistive effect element (spin valve film) used in a magnetoresistive effect element sensor;
FIG. 3 is a plan view showing the structure of a specific first embodiment of a magnetoresistive element sensor according to the present invention;
FIG. 4 is a plan view showing the structure of a specific second embodiment of a magnetoresistive effect element sensor according to the present invention;
FIG. 5 is a partial configuration diagram of a potentiometer equipped with a magnetoresistive effect element sensor according to the present invention.
FIG. 6 is an output waveform diagram output from a magnetoresistive element sensor mounted on a potentiometer;
FIG. 7 is a partial configuration diagram of an encoder equipped with a magnetoresistive element sensor according to the present invention;
FIG. 8 is an explanatory diagram showing the relationship between the magnetization of the pinned magnetic layer and the magnetization of the free magnetic layer of the magnetoresistive element sensor equipped in the encoder;
FIG. 9 is an output waveform diagram output from one output terminal of the magnetoresistive effect element sensor equipped in the encoder;
FIG. 10 is an output waveform diagram output from the other output terminal of the magnetoresistive element sensor equipped in the encoder;
11 is a plan view showing one process of manufacturing the magnetoresistive effect element sensor shown in FIG. 3;
12 is a plan view showing a process of manufacturing the magnetoresistive effect element sensor shown in FIG. 4;
FIG. 13 shows α-Fe as an antiferromagnetic layer of a magnetoresistive element.2OThreeHysteresis loop of the magnetoresistive effect element when using
FIG. 14 shows a hysteresis loop of the magnetoresistive element when an NiMn alloy is used as the antiferromagnetic layer of the magnetoresistive element;
FIG. 15 is a circuit diagram of a conventional magnetoresistive element sensor using two magnetoresistive elements;
[Explanation of symbols]
10, 31, 51 First magnetoresistive element
11, 32, 52 Second magnetoresistance effect element
12, 33, 53 Third magnetoresistance effect element
13, 34, 54 Fourth magnetoresistive element
18, 19, 37, 38, 56, 58 Output terminal
20, 42, 60 input terminals,
23 Antiferromagnetic layer
24 Fixed magnetic layer
25 Nonmagnetic conductive layer
26 Free magnetic layer
72, 80 magnets
87 DC power supply
88 conductor
90, 91 Helmholtz coils

Claims (13)

基板上に、固定磁性層と、外部磁界の影響を受けて磁化方向が変動するフリー磁性層とを有する磁気抵抗効果素子が４個設けられ、この４個の磁気抵抗効果素子のうち２個の磁気抵抗効果素子は、その固定磁性層が同一方向に磁化されて、第１の磁気抵抗効果素子と第４の磁気抵抗効果素子とされ、また残りの２個の磁気抵抗効果素子は、その固定磁性層が、前記第１と第４の磁気抵抗効果素子の固定磁性層と逆向きに磁化されて、第２の磁気抵抗効果素子と第３の磁気抵抗効果素子とされており、前記第１の磁気抵抗効果素子と第２の磁気抵抗効果素子、及び第３の磁気抵抗効果素子と第４の磁気抵抗効果素子が、磁気抵抗効果素子間に、出力部を有して直列に接続された状態で、前記２つの直列回路が並列に接続されており、各直列回路の両端が入力部とされており、
前記第１の磁気抵抗効果素子と前記第４の磁気抵抗効果素子とが、固定磁性層の磁化方向を互いに平行に向けて、基板の一方の側に配置され、前記第２の磁気抵抗効果素子と前記第３の磁気抵抗効果素子とが、固定磁性層の磁化方向を互いに平行で、且つ、前記第１の磁気抵抗効果素子と前記第４の磁気抵抗効果素子の固定磁性層の磁化方向と逆方向に向けて、基板の他方の側に配置されていることを特徴とする磁気抵抗効果素子センサ。Four magnetoresistive elements having a pinned magnetic layer and a free magnetic layer whose magnetization direction fluctuates under the influence of an external magnetic field are provided on a substrate, and two of the four magnetoresistive elements are provided. In the magnetoresistive effect element, the fixed magnetic layer is magnetized in the same direction to form a first magnetoresistive effect element and a fourth magnetoresistive effect element, and the remaining two magnetoresistive effect elements are fixed. The magnetic layer is magnetized in the opposite direction to the pinned magnetic layers of the first and fourth magnetoresistive elements to form a second magnetoresistive element and a third magnetoresistive element. The magnetoresistive effect element and the second magnetoresistive effect element, and the third magnetoresistive effect element and the fourth magnetoresistive effect element were connected in series with an output portion between the magnetoresistive effect elements. In the state, the two series circuits are connected in parallel, and each series circuit Both ends are an input unit,
The first magnetoresistive effect element and the fourth magnetoresistive effect element are arranged on one side of the substrate with the magnetization directions of the pinned magnetic layers parallel to each other, and the second magnetoresistive effect element And the third magnetoresistance effect element are parallel to each other in the magnetization direction of the pinned magnetic layer, and the magnetization direction of the pinned magnetic layer of the first magnetoresistance effect element and the fourth magnetoresistance effect element is A magnetoresistive element sensor, which is disposed on the other side of the substrate in the opposite direction . 請求項１記載の磁気抵抗効果素子センサと磁石とを平行に配置し、前記磁石を、前記磁気抵抗効果素子センサの基板に垂直な軸を中心として回転させることで、前記基板上の磁気抵抗効果素子間の抵抗変化の作動を計測することを特徴とするポテンショメータ。Claim 1 Symbol disposed parallel to the magnetoresistive effect element sensor and the magnet of the mounting, the magnet, by rotating about an axis perpendicular to the substrate of the magneto-resistive effect element sensor, a magnetoresistive on the substrate A potentiometer characterized by measuring a change in resistance between effect elements. 基板上に、固定磁性層と、外部磁界の影響を受けて磁化方向が変動するフリー磁性層とを有する磁気抵抗効果素子が４個設けられ、４個の磁気抗効果素子は、その固定磁性層がすべて同一方向に磁化され、且つ、各固定磁性層の磁化方向に向けて、一列に配列されており、２個の磁気抵抗効果素子が、両素子間に出力部を有して直列に接続され、他の２個の磁気抵抗効果素子が、両素子間に出力部を有して直列に接続されており、前記２つの直列回路が並列に接続されて、直列回路の両端が入力部とされており、
前記一列に配置された４個の磁気抵抗効果素子のうち、片側から数えて、１番目と３番目に形成された磁気抵抗効果素子が、互いに直列に接続され、また２番目と４番目に形成された磁気抵抗効果素子が、互いに直列に接続されていることを特徴とする磁気抵抗効果素子センサ。Four magnetoresistive elements having a pinned magnetic layer and a free magnetic layer whose magnetization direction varies under the influence of an external magnetic field are provided on the substrate, and the four magnetoresistive elements include the pinned magnetic layer. Are magnetized in the same direction and arranged in a line toward the magnetization direction of each pinned magnetic layer, and two magnetoresistive elements are connected in series with an output section between the two elements. The other two magnetoresistive elements are connected in series with an output section between the two elements, the two series circuits are connected in parallel, and both ends of the series circuit are connected to the input section. Has been
Of the four magnetoresistive elements arranged in a row, the first and third magnetoresistive elements counted from one side are connected in series to each other, and are formed second and fourth. A magnetoresistive effect element sensor, wherein the magnetoresistive effect elements are connected in series with each other . 請求項３記載の磁気抵抗効果素子センサが、回転方向にＮ極とＳ極とが交互に形成された回転ドラムに対向して配置されており、前記回転ドラムを回転させることで、前記磁気抵抗効果素子センサに形成された磁気抵抗効果素子間の抵抗変化を計測することを特徴とするエンコーダ。Magnetoresistive element sensor of claim 3 Symbol placement is, the N and S poles in the rotational direction are disposed to face the rotary drum formed alternately, by rotating the rotary drum, the magnetic An encoder that measures a resistance change between magnetoresistive elements formed in a resistive element sensor. 前記Ｎ極とＳ極との間隔は、磁気抵抗効果素子センサ上に一列に配置された各磁気抵抗効果素子の間隔の２倍に形成されている請求項４記載のエンコーダ。5. The encoder according to claim 4, wherein a distance between the N pole and the S pole is formed twice as long as a distance between the magnetoresistive elements arranged in a line on the magnetoresistive element sensor. 磁気抵抗効果素子の固定磁性層の保磁力は、フリー磁性層の保磁力に比べて大きくなっている請求項１または３に記載の磁気抵抗効果素子センサ。The magnetoresistive effect element sensor according to claim 1 or 3, wherein the coercive force of the pinned magnetic layer of the magnetoresistive effect element is larger than that of the free magnetic layer. 前記固定磁性層に接する一方の層には、反強磁性層が形成され、前記反強磁性層は、α―Ｆｅ２Ｏ３で形成されている請求項１、３、６のいずれかに記載の磁気抵抗効果素子センサ。Wherein the one layer in contact with the fixed magnetic layer, an antiferromagnetic layer is formed, the antiferromagnetic layer is claim 1 which is formed by the α-Fe 2 O 3, according to any one of 3, 6 Magnetoresistive element sensor. 前記固定磁性層は、硬磁性材料で形成されている請求項１、３、６のいずれかに記載の磁気抵抗効果素子センサ。The fixed magnetic layer, Section claims are formed of hard magnetic material 1, 3,6 magnetoresistive element sensor according to any of. 固定磁性層と、外部磁界の影響を受けて磁化が変動するフリー磁性層とを有する磁気抵抗効果素子を４個基板上に形成し、このとき、基板の一方の側に第１の磁気抵抗効果素子と第２の磁気抵抗効果素子を並べて配置し、基板の他方の側に第３の磁気抵抗効果素子と第４の磁気抵抗効果素子を並べて配置する工程と、
前記第１の磁気抵抗効果素子と第２の磁気抵抗効果素子、及び第３の磁気抵抗効果素子と第４の磁気抵抗効果素子を、素子の中間に出力部を有するように直列に接続する工程と、
前記２つの直列回路を並列に接続すると共に、直列回路の両端に入力部を形成する工程と、
第１の磁気抵抗効果素子と第４の磁気抵抗効果素子の上、及び第２の磁気抵抗効果素子と第３の磁気抵抗効果素子の上にそれぞれ導線を配置し、２本の導線に流す電流の方向を逆向きとして、第１の磁気抵抗効果素子と第４の磁気抵抗効果素子の固定磁性層の磁化と、第２の磁気抵抗効果素子と第３の磁気抵抗効果素子の固定磁性層の磁化とを逆向きに固定する工程と、
を有することを特徴とする磁気抵抗効果素子センサの製造方法。Four magnetoresistive elements having a pinned magnetic layer and a free magnetic layer whose magnetization varies under the influence of an external magnetic field are formed on a substrate. At this time, the first magnetoresistive effect is formed on one side of the substrate. Arranging the element and the second magnetoresistive element side by side, and arranging the third magnetoresistive element and the fourth magnetoresistive element side by side on the other side of the substrate;
Connecting the first magnetoresistive element and the second magnetoresistive element, and the third magnetoresistive element and the fourth magnetoresistive element in series so as to have an output portion in the middle of the element When,
Connecting the two series circuits in parallel and forming an input at both ends of the series circuit;
Conductive wires are arranged on the first magnetoresistive element and the fourth magnetoresistive element, and on the second magnetoresistive element and the third magnetoresistive element, respectively, and currents flow through the two conductive lines. Are reversed, the magnetizations of the pinned magnetic layers of the first and fourth magnetoresistive elements, and the pinned magnetic layers of the second and third magnetoresistive elements. Fixing the magnetization in the opposite direction;
A method for manufacturing a magnetoresistive element sensor, comprising: 固定磁性層と、外部磁界の影響を受けて磁化が変動するフリー磁性層とを有する磁気抵抗効果素子を、基板上に４個一列に形成する工程と、
片側から数えて、１番目と３番目の磁気抵抗効果素子を両素子間に出力部を形成して直列に接続する工程と、
２番目と４番目の磁気抵抗効果素子を両素子間に出力部を形成して直列に接続する工程と、
前記２つの直列回路を並列に接続し、直列回路の両端に入力部を形成する工程と、
前記４個の磁気抵抗効果素子に対して、その配列方向に向く磁場を与えて、全ての磁気抵抗効果素子の固定磁性層を同じ方向に磁化させることを特徴とする磁気抵抗効果素子センサの製造方法。Forming a magnetoresistive effect element having a fixed magnetic layer and a free magnetic layer whose magnetization fluctuates under the influence of an external magnetic field in a row on a substrate;
A step of connecting the first and third magnetoresistive elements, counting from one side, in series by forming an output portion between the two elements;
Connecting the second and fourth magnetoresistive elements in series by forming an output portion between the two elements;
Connecting the two series circuits in parallel and forming input portions at both ends of the series circuit;
Producing a magnetoresistive element sensor, wherein a magnetic field directed to the arrangement direction is applied to the four magnetoresistive elements to magnetize the fixed magnetic layers of all the magnetoresistive elements in the same direction. Method. 前記４個の磁気抵抗効果素子のそれぞれの上に導線を配置し、前記導線に電流を流すことによって、前記４個の磁気抵抗効果素子の固定磁性層を同じ方向に磁化させる請求項１０記載の磁気抵抗効果素子センサの製造方法。The conductor is disposed on top of each of the four magnetic resistance effect element, by supplying a current to the wire, according to claim 10, wherein magnetizing the fixed magnetic layer of the four magnetic resistance effect element in the same direction Manufacturing method of magnetoresistive element sensor. 前記磁気抵抗効果素子の固定磁性層に接する一方の層をα―Ｆｅ２Ｏ３で形成された反強磁性層で形成する請求項９ないし請求項１１のいずれかに記載の磁気抵抗効果素子センサの製造方法。Magnetoresistive element sensor according to any of claims 9 to 11 to form an antiferromagnetic layer one layer in contact with the fixed magnetic layer of the magnetoresistive effect element is formed by α-Fe 2 O 3 Manufacturing method. 前記磁気抵抗効果素子の固定磁性層を、硬磁性材料で形成する請求項９ないし請求項１１のいずれかに記載の磁気抵抗効果素子センサの製造方法。Method for manufacturing a magneto-resistance effect element sensor according to any of claims 9 to 11, the fixed magnetic layer of the magnetoresistive element is formed by a hard magnetic material.
JP21518398A 1998-07-30 1998-07-30 Magnetoresistive element sensor, potentiometer and encoder using the same, and method for manufacturing magnetoresistive element sensor Expired - Lifetime JP3964055B2 (en)

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