JP2004047583A - Magnetoresistance effect element, and magnetic head, magnetic memory, and magnetic recording equipment using the magnetoresistance effect element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetoresistance effect element (MR element) with a high output superior in heat resistance corresponding to a high temperature heat treatment process, a heat cycle or the like in the MR element including a structure laminating a pair of magnetic layers via a non-magnetic layer, and to provide a magnetic head, a magnetic memory (MRAM) superior in heat resistance and magnetic recording equipment. <P>SOLUTION: The MR element includes a magnetic stable layer 4 changing a magnetic reverse magnetic field of the magnetic layer 3 and has superior heat resistance by controlling the average particle diameter of the crystal grain of a material constituting the magnetic stable layer 4 and the distance between the magnetic stable layer 4 and the non-magnetic layer 1. In addition, the magnetic head and MRAM superior in heat resistance and magnetic recording equipment are obtained by using the MR element. <P>COPYRIGHT: (C)2004,JPO

Description

【０１１９】
表１に示すように、Ｎｉ−Ｆｅ−Ｃｒ層の膜厚Ｘ_１が大きくなるにつれて、Ｎｉ−Ｆｅ−Ｃｒ層に隣接する磁化安定層の平均粒径Ｄが増加し、熱処理後のＭＲ比が向上することがわかる。このとき、平均粒径Ｄの全範囲がＤ≧２×Ｈの関係を満たして、ＭＲ比の向上が得られていることがわかる。
【０１２０】
表１に示した平均粒径Ｄおよび熱処理後のＭＲ比について、Ｎｉ−Ｆｅ−Ｃｒ層の膜厚Ｘ_１を横軸に用いて表したグラフを図２７に示す。図２７において、平均粒径Ｄの値を示す棒線は、得られた平均粒径Ｄの値の範囲を反映したものである（以降の図２８および図２９においても同様である）。
【０１２１】
図２７によれば、粒径制御層を設けることにより、熱処理後の素子のＭＲ比を向上できる（粒径制御層を有さない従来例では、熱処理後のＭＲ比＝０％）が、なかでも、膜厚Ｘ_１が４ｎｍ以上（即ち、平均粒径Ｄが１０ｎｍ以上）において特にＭＲ比が向上していることがわかる。
【０１２２】
続けて、サンプルａ２について、磁化安定層と非磁性層との距離Ｈを変化させたサンプルを６種類準備し（Ｈ＝Ｈ_１＝２、３、４、５、６および８ｎｍ）、それぞれ磁化安定層の平均粒径Ｄと、素子のＭＲ特性として熱処理（４００℃）後のＭＲ比とを測定した。その測定結果を表２に示す。なお、サンプルａ１と同様、ｎ＝１５で測定を行い、ＭＲ比は、ｎ＝１５で得られたすべての値の平均値で示し、平均粒径Ｄは、ｎ＝１回の測定での粒界間距離の平均値をまず求め、ｎ＝１５のそれぞれで得られた上記平均値の範囲で示す。
【０１２３】
【表２】

【０１２４】
粒径制御層（Ｎｉ−Ｆｅ−Ｃｒ（４））を設けることで、平均粒径Ｄはすべて１０ｎｍ以上となり、従来例に比べて大きくＭＲ比が向上した。さらに、距離Ｈが増加することで得られるＭＲ比がより向上し、距離Ｈが５ｎｍ以上では約４０％のＭＲ比を得ることができた。平均粒径Ｄおよび距離Ｈを制御することで、より耐熱性に優れたＭＲ素子が得られることがわかる。なお、表２に示した平均粒径Ｄおよび熱処理後のＭＲ比について、距離Ｈを横軸に用いて表したグラフを図２８に示す。
【０１２５】
次に、サンプルａ３について、磁化安定層と非磁性層との距離Ｈを変化させたサンプルを６種類準備し（Ｈ＝Ｈ_２＝２、３、４、５、８および１０ｎｍ）、それぞれ磁化安定層の平均粒径Ｄと、素子のＭＲ特性として熱処理（４００℃）後のＭＲ比とを測定した。その測定結果を表３に示す。なお、サンプルａ１と同様、ｎ＝１５で測定を行い、ＭＲ比は、ｎ＝１５で得られたすべての値の平均値で示し、平均粒径Ｄは、ｎ＝１回の測定での粒界間距離の平均値をまず求め、ｎ＝１５のそれぞれで得られた上記平均値の範囲で示す。
【０１２６】
【表３】

【０１２７】
表３に示すように、素子の膜構成に粒径制御層を含まないため、磁化安定層の平均粒径Ｄの値は０．５〜２．５ｎｍと小さく、従来例と同様であった。しかし、距離Ｈが４ｎｍ以上（即ち、距離Ｈが、Ｈ≧１．４×Ｄの関係を満たす）において、熱処理後のＭＲ比を向上させることができた。なお、表３に示した平均粒径Ｄおよび熱処理後のＭＲ比について、距離Ｈを横軸に用いて表したグラフを図２９に示す。
【０１２８】
ここで、４００℃の熱処理後における平均粒径Ｄが、１ｎｍ≦Ｄ＜１０ｎｍの結果となったサンプルを含む、サンプルａ１とサンプルａ３における各サンプル（それぞれ６種類づつの計１２サンプル）について、１．４×Ｄ／Ｈを横軸に、２×Ｈ／Ｄを縦軸にプロットしたグラフを図３０に示す。図３０のグラフにおいて、各サンプルのプロットに分布がみられるのは、各サンプルの測定で得られた平均粒径Ｄの値に分布があることに対応している。なお、グラフの凡例における「ａ１」および「ａ３」は、それぞれ、「サンプルａ１」および「サンプルａ３」を、「Ｘ１」は、サンプルａ１における「Ｎｉ−Ｆｅ−Ｃｒ層の膜厚Ｘ_１」を、「Ｈ」は、サンプルａ３における「磁化安定層と非磁性層との距離Ｈ」を意味している。
【０１２９】
図３０と、表１および表３との結果を比較すると、１．４×Ｄ／Ｈ≦１または２×Ｈ／Ｄ≦１の関係を満たす場合（即ち、Ｈ≧１．４×ＤまたはＤ≧２×Ｈの関係を満たす場合）にＭＲ素子の耐熱性が向上していることがわかる。このとき、各サンプルのプロットの分布すべてが（即ち、得られた平均粒径Ｄの範囲すべてが）、上記の関係を満たすことが好ましいといえる。
【０１３０】
上記の表１〜表３に示したように、磁化安定層の平均粒径Ｄが１０ｎｍ以上の場合、あるいは、平均粒径Ｄと距離Ｈとが、Ｄ≧２×ＨまたはＨ≧１．４×Ｄの関係を満たす場合に、耐熱性に優れたＭＲ素子を得ることができる。なかでも、平均粒径Ｄが１０ｎｍ以上の場合、ＭＲ特性が特に向上したＭＲ素子を得ることができる。
【０１３１】
このように、高温の熱処理前後におけるＭＲ特性の変化は、反強磁性層などの磁化安定層の結晶粒サイズや、磁化安定層と非磁性層との距離に依存している可能性がある。本実施例では、磁化安定層である反強磁性層の結晶粒サイズがより大きいほど、あるいは、反強磁性層と、ＭＲ特性に大きく寄与していると考えられる非磁性層との距離がより離れているほど、高温時におけるＭＲ特性劣化が抑制される傾向が示された。上記のような構成の素子とすることで、反強磁性層中の拡散元素種であるＭｎの非磁性層への拡散が抑制されていることが考えられる。
【０１３２】
また、本実施例の各サンプルにおけるＰｔ−Ｍｎ層について、ＩＣＰおよびＥＰＭＡ（電子線マイクロアナリシス）を用いて、その組成偏在を評価した。従来例であるサンプルａ０のＰｔ−Ｍｎ層では、結晶粒界周辺部を中心に、Ｍｎ含有量が６０ａｔ％以上の領域が偏在しているのが確認されたが、上記組成偏在領域は、Ｐｔ−Ｍｎ層のおよそ２５ｖｏｌ％を占めていることがわかった。
【０１３３】
このような組成偏在は、スパッタ法による膜作製時に組成ずれが起き、そのずれが結晶粒界周辺に偏析することによって発生する可能性がある。特にＰｔ−Ｍｎ層の薄膜作製条件が不適切である場合、上記組成ずれが顕著に現われ、Ｐｔ−Ｍｎ層の組成が磁化安定層としての最適組成からずれるに伴って、Ｍｎの偏在がより強くなり、熱処理後のＭＲ特性が劣化する傾向にある。明確ではないが、このような組成偏在が、従来例であるサンプルａ０における高温の熱処理に伴うＭＲ特性劣化の原因である可能性がある。
【０１３４】
一方、サンプルａ１やサンプルａ２においても、結晶粒界周辺部を中心に、Ｍｎ含有量が６０ａｔ％以上の領域が偏在しているのが確認されたが、その領域は、Ｐｔ−Ｍｎ層のおよそ２５ｖｏｌ％以下であった。粒径制御層の存在によってＰｔ−Ｍｎ層の結晶粒径が大きくなったことで、Ｐｔ−Ｍｎ層に存在する粒界自体が少なくなっていることに起因している可能性がある。
【０１３５】
以上の結果から、磁化安定層が式Ｍｎ−Ｚ（ただし、Ｚは、Ｐｔ、Ｐｄ、Ｆｅ、Ｉｒ、Ｎｉ、Ｃｏ、Ｒｈ、Ｏ、Ｃ、Ｆ、ＮおよびＢから選ばれる少なくとも１種の元素）で示される組成を有する合金からなる反強磁性層である場合（本実施例において、ＺはＰｔ）、Ｍｎ含有率が６０ａｔ％以上である組成偏在領域が、磁化安定層全体の２５ｖｏｌ％以下であることが好ましいといえる。このような条件では、高温の熱処理におけるＭＲ特性劣化がより抑制され、熱処理後により高いＭＲ比を確保することができる。また、この条件は、粒径制御層を配置することによって実現可能である。
【０１３６】
なお、本実施例では、粒径制御層としてＮｉ−Ｆｅ−Ｃｒ層を用いたが、その他、Ｐｔ、Ｔａ、Ｎｂ、Ｈｆ、Ｚｒ、Ｃｒ、Ｎｉ−Ｆｅなどを用いても同様の結果を得ることができた。また、粒径制御層としてＰｔを用いる場合、１００〜４００℃程度の加熱条件下でＰｔ層を作製すると、Ｐｔ層の結晶性が向上し、磁化安定層の平均粒径をより大きくすることが可能であった。
【０１３７】
（実施例２）
［サンプルｂ０（従来例）］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｐｔ−Ｍｎ（２５）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）［サンプルｂ１］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｐｔ−Ｍｎ（２５）／Ｃｏ−Ｆｅ（Ｈ_３）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（Ｈ_３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｂ２］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／ＮｉＦｅＣｒ（４）／Ｐｔ−Ｍｎ（２５）／Ｃｏ−Ｆｅ（Ｈ_４）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（Ｈ_４）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｂ３］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／ＮｉＦｅＣｒ（４）／Ｐｔ−Ｍｎ（２５）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（１）／Ｎｉ−Ｆｅ（３）／Ｒｕ（０．７）／Ｎｉ−Ｆｅ（２）／Ｔａ（２０）
【０１３８】
基板上のＴａ（３）／Ｃｕ（５０）／Ｔａ（３）は下部電極であり、Ｐｔ−Ｍｎ（２５）は反強磁性層からなる磁化安定層である。このＰｔ−Ｍｎ層に隣接するＮｉＦｅＣｒ（４）は粒径制御層である。また、基板から最も遠いＴａ（２０）は保護層（上部電極の一部を兼ねている）である。Ｈ_３およびＨ_４は、Ｃｏ−Ｆｅ層について膜厚の異なるサンプルを数通り準備したことを示しており、Ｈ_３、Ｈ_４ともに、２、３、４および５ｎｍの４通りを準備した。なお、Ｐｔ−Ｍｎ層、Ｎｉ−Ｆｅ−Ｃｒ層、Ｃｏ−Ｆｅ層およびＮｉ−Ｆｅ層の組成は、それぞれＰｔ_４９Ｍｎ_５１、Ｎｉ_６０Ｆｅ_１５Ｃｒ_２５、Ｃｏ_５０Ｆｅ_５０およびＮｉ_８０Ｆｅ_２０であった。
【０１３９】
各サンプルとも実施例１と同様に成膜、上部電極の形成を行った後、２８０℃、５ｋＯｅ（４．０×１０^５Ａ／ｍ）の磁場中で５時間熱処理し、Ｐｔ−Ｍｎ層に磁界異方性を付与した。なお、サンプルの素子サイズは、いずれも１．５μｍ×３μｍとした。
【０１４０】
上記のようにして準備した各サンプルに対し、磁化安定層の平均粒径Ｄを測定した後、熱処理を加えた場合のＭＲ特性の変化（ＭＲ特性の熱処理温度依存性）を調べた。まず、無磁界、水素雰囲気下において各サンプルを熱処理温度（４００℃）にまで加熱し、３０分保持した後に、室温まで冷却し、ＭＲ特性としてＭＲ比を求めた。
【０１４１】
従来例であるサンプルｂ０の熱処理前のＭＲ比は約４０％であったが、熱処理によってＭＲ特性が大きく劣化し、熱処理後のＭＲ比は０％となった。サンプルｂ０について、同じ膜構成のサンプルを１５個準備して同様の測定を行ったが、すべて同じ結果となった。なお、サンプルｂ０における磁化安定層の平均粒径Ｄの範囲は、０．５〜２．５ｎｍであった。
【０１４２】
次に、積層フェリ固定層を導入することで、磁化安定層である反強磁性層と非磁性層との距離Ｈを大きくしたサンプルｂ１の測定結果を表４に示す。なお、他のサンプルと同様に、測定はｎ＝１５で行い、ＭＲ比は、ｎ＝１５で得られたすべての値の平均値で示し、平均粒径Ｄは、ｎ＝１回の測定での粒界間距離の平均値をまず求め、ｎ＝１５のそれぞれで得られた上記平均値の範囲で示す。
【０１４３】
【表４】

【０１４４】
表４に示すように、サンプルｂ１では４００℃の熱処理後もＭＲ比が０％となることはなく、従来例に比べて素子の耐熱性が向上していることがわかる。また、距離Ｈが大きくなるに伴い、より大きなＭＲ比を得ることができた。
【０１４５】
次に、サンプルｂ１にさらに粒径制御層を配置した膜構成のサンプルｂ２の測定結果を表５に示す。なお、他のサンプルと同様に、測定はｎ＝１５で行い、ＭＲ比は、ｎ＝１５で得られたすべての値の平均値で示し、平均粒径Ｄは、ｎ＝１回の測定での粒界間距離の平均値をまず求め、ｎ＝１５のそれぞれで得られた上記平均値の範囲で示す。
【０１４６】
【表５】

【０１４７】
粒径制御層を有するサンプルｂ２では、サンプルｂ１に比べて、さらに耐熱性に優れる高出力のＭＲ素子となった。粒径制御層を設けることにより、磁化安定層の平均粒径Ｄが１０ｎｍ以上となった効果が大きいと考えられる。
【０１４８】
また、サンプルｂ１とｂ２について、ＭＲ比を求めるための磁気抵抗測定におけるマイナー曲線を比較したところ、図３１に示す結果となった。図３１（ａ）がサンプルｂ２のマイナー曲線、図３１（ｂ）がサンプルｂ１のマイナー曲線である。
【０１４９】
図３１（ｂ）に示すように、サンプルｂ１では、熱処理後のＭＲ比が向上し、ＭＲ素子としての使用には問題がないものの、スピンバルブ特性が乱れる結果となった。それに対し、サンプルｂ２では、ＭＲ比がより向上しただけではなく、スピンバルブ特性に全く乱れが生じなかった。粒径制御層を設けることにより、磁化安定層の平均粒径Ｄが１０ｎｍ以上となった効果による可能性が考えられる。
【０１５０】
次に、サンプルｂ２にさらに積層フェリ自由層を導入したサンプルｂ３では、４００℃の熱処理後もサンプルｂ２とほぼ同様のＭＲ比を得ることができ、スピンバルブ特性にも全く乱れが生じなかった。また、積層フェリ自由層を設けることで、自由磁性層の磁化反転磁界の低下も同時に実現することができた。
【０１５１】
本実施例においても実施例１と同様に、磁化安定層である反強磁性層の結晶粒サイズがより大きいほど、あるいは、反強磁性層と、ＭＲ特性に大きく寄与すると考えられる非磁性層との距離がより離れているほど、高温時におけるＭＲ特性劣化が抑制される傾向が示された。上記のような構成の素子とすることで、反強磁性層中の拡散元素種であるＭｎの非磁性層への拡散が抑制されていることが考えられる。
【０１５２】
（実施例３）
本実施例では、さらに拡散制御層が設けられた例について示す。
【０１５３】
［サンプルｃ０−Ａ（比較例）］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｉｒ−Ｍｎ（２５）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｃ０−Ｂ（比較例）］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｎｉ−Ｆｅ（３）／Ｃｏ−Ｆｅ（２）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ｉｒ−Ｍｎ（２０）／Ｔａ（２０）
［サンプルｃ１］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｉｒ−Ｍｎ（２５）／Ｍ−Ｘ（２）／Ｃｏ−Ｆｅ（１）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｃ２］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｎｉ−Ｆｅ（３）／Ｃｏ−Ｆｅ（２）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（１）／Ｍ−Ｘ（２）／Ｉｒ−Ｍｎ（２０）／Ｔａ（２０）
［サンプルｃ３］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／ＮｉＦｅＣｒ（４）／Ｉｒ−Ｍｎ（２５）／Ｍ−Ｘ（２）／Ｃｏ−Ｆｅ（１）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｃ４］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／ＮｉＦｅＣｒ（４）／Ｉｒ−Ｍｎ（２５）／Ｍ−Ｘ（２）／Ｃｏ−Ｆｅ（２）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（４）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｃ５］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｍ−Ｘ（２）／Ｉｒ−Ｍｎ（２５）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｃ６］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｍ−Ｘ（２）／Ｉｒ−Ｍｎ（２５）／Ｍ−Ｘ（２）／Ｃｏ−Ｆｅ（１）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
【０１５４】
基板上のＴａ（３）／Ｃｕ（５０）／Ｔａ（３）は下部電極であり、Ｉｒ−Ｍｎ（２５）およびＩｒ−Ｍｎ（２０）は反強磁性層からなる磁化安定層である。このＩｒ−Ｍｎ層に隣接するＮｉＦｅＣｒ（４）は粒径制御層である。また、基板から最も遠いＴａ（２０）は保護層（上部電極の一部を兼ねている）である。なお、Ｉｒ−Ｍｎ層、Ｎｉ−Ｆｅ−Ｃｒ層、Ｃｏ−Ｆｅ層およびＮｉ−Ｆｅ層の組成は、それぞれＩｒ_２０Ｍｎ_８０、Ｎｉ_６０Ｆｅ_１５Ｃｒ_２５、Ｃｏ_５０Ｆｅ_５０およびＮｉ_８０Ｆｅ_２０であった。
【０１５５】
また、各サンプルのＭ−Ｘ層は、強磁性材料Ｍ−Ｘからなる拡散制御層である。
【０１５６】
各サンプルとも実施例１と同様に成膜、上部電極の形成を行った後、２８０℃、５ｋＯｅ（４．０×１０^５Ａ／ｍ）の磁場中で５時間熱処理し、Ｉｒ−Ｍｎ層に磁界異方性を付与した。なお、サンプルの素子サイズは、いずれも１．５μｍ×３μｍとした。
【０１５７】
上記のようにして準備した各サンプルに対し、磁化安定層の平均粒径Ｄを求めた後、熱処理を加えた場合のＭＲ特性の変化（ＭＲ特性の熱処理温度依存性）を調べた。まず、無磁界、水素雰囲気下において各サンプルを熱処理温度（４００℃）にまで加熱し、３０分保持した後に、室温まで冷却し、ＭＲ特性としてＭＲ比を求めた。
【０１５８】
サンプルｃ０Ａ、ｃ０Ｂ、ｃ１〜ｃ４における測定結果を表６に示す。なお、実施例１および２と同様に、測定はｎ＝１５で行い、ＭＲ比はその平均値、平均粒径Ｄは得られた値の範囲で示す。
【０１５９】
【表６】

【０１６０】
比較例であるサンプルｃ０Ａは、磁化安定層としてＩｒ−Ｍｎ層が用いられていることを除けば、実施例２におけるサンプルｂ１と同様の膜構成を有するサンプルである。サンプルｃ０Ａは、熱処理前には３５％のＭＲ比を示していたが、熱処理後に得られたＭＲ比は４％であった。また、同じく比較例であるサンプルｃ０Ｂは、磁化安定層であるＩｒ−Ｍｎ層を、素子の上部（非磁性層を挟んで基板と反対側）に配置した素子であり、熱処理前には３０％のＭＲ比を示していたが、熱処理後に得られたＭＲ比は２％であった。磁化安定層の平均粒径Ｄは、サンプルｃ０Ａ、サンプルｃ０Ｂともに０．５〜２．５ｎｍであった。しかし両サンプルとも、磁化安定層と非磁性層との距離Ｈを、Ｈ≧１．４×Ｄの関係を満たす値としたため、サンプルａ０やサンプルｂ０のような従来例とは異なり、４００℃での熱処理後においてもＭＲ出力を得ることができた。ただし、サンプルｃ０Ａ、ｃ０Ｂともに、スピンバルブ特性は乱れる結果となった。
【０１６１】
サンプルｃ１は、サンプルｃ０Ａに、強磁性材料Ｍ−Ｘからなる拡散制御層を導入した膜構成のサンプルである。
【０１６２】
強磁性材料Ｍ−Ｘとして、例えば、Ｆｅ−Ｐｔ（Ｐｔの組成が５〜１０ａｔ％）を用いた場合、４００℃における熱処理後のＭＲ比は３５％を越え、比較例であるサンプルｃ０Ａよりもさらに耐熱性の向上した素子となった。しかし、図３２に示すように、ＭＲ素子として使用するには問題ないものの、スピンバルブ特性は乱れてしまった。図３２（ａ）が熱処理前のマイナー曲線、図３２（ｂ）が熱処理後のマイナー曲線である。
【０１６３】
サンプルｃ２は、サンプルｃ０Ｂに、強磁性材料Ｍ−Ｘからなる拡散制御層を導入した膜構成のサンプルである。同じく強磁性材料Ｍ−Ｘとして、例えば、Ｆｅ−Ｐｔ（Ｐｔの組成が５〜１０ａｔ％）を用いた場合、４００℃における熱処理後のＭＲ比は２７％と比較例（サンプルｃ０Ｂ）に対して大幅に向上する結果となった。ただし、サンプルｃ２においても、サンプルｃ１と同様に、スピンバルブ特性が乱れる結果となった。
【０１６４】
サンプルｃ１にさらに粒径制御層を付加したサンプルｃ３（強磁性材料Ｍ−Ｘはサンプルｃ１と同じ）では、平均粒径Ｄが１０ｎｍ以上になるとともに、４００℃における熱処理後のＭＲ比がサンプルｃ１に比べてさらに上昇し、より耐熱性に優れたＭＲ素子を得ることができた。また、スピンバルブ特性も乱れることなく維持することができた。
【０１６５】
サンプルｃ３の距離Ｈをさらに大きくしたサンプルであるサンプルｃ４（強磁性材料Ｍ−Ｘはサンプルｃ３と同じ）では、さらにＭＲ比の向上が認められた。
【０１６６】
また、サンプルｃ５（強磁性材料Ｍ−Ｘはサンプルｃ１〜ｃ４と同じ）のように、磁化安定層であるＩｒ−Ｍｎ層と基板との間に、強磁性材料Ｍ−Ｘからなる拡散制御層を配置したサンプルにおいても、４００℃の熱処理後に１０％以上のＭＲ比を得ることができ、サンプルａ０やサンプルｂ０などの従来例に比べて耐熱性に優れたＭＲ素子とすることができた。サンプルｃ６（強磁性材料Ｍ−Ｘはサンプルｃ１〜ｃ５と同じ）のように、磁化安定層の両面に強磁性材料Ｍ−Ｘからなる拡散制御層を配置したサンプルにおいても、４００℃の熱処理後に３５％以上のＭＲ比を示し、耐熱性に優れたＭＲ素子とすることができた。
【０１６７】
上記の結果から、磁化安定層の平均粒径Ｄと距離Ｈとを制御し、拡散制御層および／または粒径制御層をさらに配置することによって、より耐熱性に優れたＭＲ素子が得られることがわかる。
【０１６８】
なお、本実施例では、強磁性材料Ｍ−ＸとしてＦｅ−Ｐｔ（Ｐｔの組成が５〜１０ａｔ％）を用いた例を示したが、その他、Ｍとして、Ｆｅ、ＣｏおよびＮｉから選ばれる少なくとも１種の磁性元素を、Ｘとして、Ｃｕ、Ｒｕ、Ｒｈ、Ｐｄ、Ａｇ、Ｏｓ、Ｉｒ、Ｐｔ、Ａｕ、Ａｌ、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｈｆ、Ｔａ、Ｗ、Ｒｅ、Ｇａ、Ｇｅ、ランタノイド、Ｓｉ、Ｂ、Ｃ、Ｎ、Ｏ、ＰおよびＳから選ばれる少なくとも１種の非磁性元素を用いた場合においても耐熱性に優れたＭＲ素子を得ることができた。
【０１６９】
サンプルｃ０３において、強磁性材料Ｍ−Ｘの組成を変化させ、他のサンプルと同じ４００℃の熱処理後に得られたＭＲ比を表７〜表１１に示す。
【０１７０】
【表７】

【０１７１】
【表８】

【０１７２】
【表９】

【０１７３】
【表１０】

【０１７４】
【表１１】

【０１７５】
表７〜表１１に示すように、上記した強磁性材料Ｍ−Ｘからなる拡散制御層を配置することで、より耐熱性に優れたＭＲ素子が得られることがわかる。
【０１７６】
（実施例４）
［サンプルｄ０（従来例）］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｐｔ−Ｍｎ（２０）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．８）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（１．０）／Ｎｉ−Ｆｅ（３）／Ａｌ−Ｏ（１．０）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．８）／Ｃｏ−Ｆｅ（３）／Ｐｔ−Ｍｎ（２０）／Ｔａ（１５）
［サンプルｄ１］
熱酸化膜付Ｓｉ基板／Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／ＮｉＦｅＣｒ（５）／Ｐｔ−Ｍｎ（２０）／Ｆｅ−Ｐｔ（２）／Ｃｏ−Ｆｅ（１）／Ｒｕ（０．８）／Ｃｏ−Ｆｅ（１）／Ｆｅ−Ｐｔ（２）／Ａｌ−Ｏ（１．０）／Ｎｉ−Ｆｅ（３）／Ａｌ−Ｏ（１．０）／Ｆｅ−Ｐｔ（２）／Ｃｏ−Ｆｅ（１）／Ｒｕ（０．８）／Ｃｏ−Ｆｅ（１）／Ｆｅ−Ｐｔ（２）／Ｐｔ−Ｍｎ（１５）／Ｔａ（１５）
【０１７７】
基板上のＴａ（３）／Ｃｕ（５０）／Ｔａ（３）は下部電極であり、Ｐｔ−Ｍｎ（２０）およびＰｔ−Ｍｎ（１５）は反強磁性層からなる磁化安定層である。このＰｔ−Ｍｎ層に隣接するＮｉＦｅＣｒ（５）は粒径制御層である。また、基板から最も遠いＴａ（１５）は保護層（上部電極の一部を兼ねている）であり、Ｆｅ−Ｐｔ層は強磁性材料Ｍ−Ｘからなる拡散制御層である。なお、Ｐｔ−Ｍｎ層、Ｎｉ−Ｆｅ−Ｃｒ層、Ｃｏ−Ｆｅ層、Ｎｉ−Ｆｅ層およびＦｅ−Ｐｔ層の組成は、それぞれＰｔ_４９Ｍｎ_５１、Ｎｉ_６０Ｆｅ_１５Ｃｒ_２５、Ｃｏ_５０Ｆｅ_５０、Ｎｉ_８０Ｆｅ_２０、Ｆｅ_０．８５Ｐｔ_０．１５であった。
【０１７８】
各サンプルとも実施例１と同様に成膜、上部電極の形成を行った後、２８０℃、５ｋＯｅ（４．０×１０^５Ａ／ｍ）の磁場中で５時間熱処理し、Ｐｔ−Ｍｎ層に磁界異方性を付与した。なお、サンプルの素子サイズは、いずれも０．５μｍ×１μｍとした。
【０１７９】
上記のようにして準備した各サンプルに対し、磁化安定層の平均粒径Ｄを求めた後、熱処理を加えた場合のＭＲ特性の変化（ＭＲ特性の熱処理温度依存性）を調べた。まず、無磁界、水素雰囲気下において各サンプルを熱処理温度（４００℃）にまで加熱し、３０分保持した後に、室温まで冷却し、ＭＲ特性としてＭＲ比を求めた。
【０１８０】
従来例であるサンプルｄ０は、熱処理前にＭＲ比約３５％以上を示していたが、熱処理によって大きくＭＲ特性が劣化し、得られるＭＲ比が０％となった。同じ膜構成のサンプルを１５個準備して同様の測定を行ったが、すべて同じ結果となった。なお、サンプルｄ０における磁化安定層の平均粒径Ｄは、０．５〜２．５ｎｍであった。
【０１８１】
サンプルｄ１は、従来例であるサンプルｄ０に拡散制御層および粒径制御層を付加した一例であるが、熱処理後に得られたＭＲ比は５０％を越える結果となり、従来例と比較して大幅に耐熱性の向上が認められた。磁化安定層の平均粒径Ｄは、１０ｎｍ〜２５ｎｍであり、スピンバルブ特性も乱れることなく維持可能であった。
【０１８２】
次に、熱処理前後におけるサンプルｄ０およびサンプルｄ１のバイアス電圧依存性を求めた。一般にＭＲ素子において、バイアス電圧の印加に伴い素子のＭＲ比は低下する。バイアス電圧を印加しない（厳密には、バイアス電圧が０に近い）状態での素子のＭＲ比を基準として、ＭＲ比が半分になったときのバイアス電圧Ｖ_ｈを、熱処理前と熱処理後、それぞれについて求めた。
測定結果を表１２に示す。
【０１８３】
（表１２）
――――――――――――――――――――――――――――
サンプルＮｏ．　　　　　　熱処理前Ｖ_ｈ（ｍＶ）　　　熱処理後Ｖ_ｈ（ｍＶ）
――――――――――――――――――――――――――――
サンプルｄ０　　　　　　９５０　　　　　　　　　　　　　　　　６９０
サンプルｄ１　　　　　　１５００　　　　　　　　　　　　　　　１６４０
――――――――――――――――――――――――――――
【０１８４】
表１２に示すように、従来例であるサンプルｄ０では、熱処理によりＶ_ｈが低下している。一方、サンプルｄ１では、熱処理後もＶ_ｈは低下せず、むしろ増加する結果となった。この結果からも、サンプルｄ１が従来例に比べより耐熱性に優れた素子であることがわかる。
【０１８５】
（実施例５）
［サンプルｅ０（従来例）］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／Ｐｔ−Ｍｎ（２５）／Ｃｏ−Ｆｅ（３）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
［サンプルｅ１］
熱酸化膜付Ｓｉ基板／
Ｔａ（３）／Ｃｕ（５０）／Ｔａ（３）／ＮｉＦｅＣｒ（４）／Ｐｔ−Ｍｎ（２５）／Ｃｏ−Ｆｅ−Ｂ（１）／Ｃｏ−Ｆｅ（２）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３）／Ａｌ−Ｏ（０．７）／Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３）／Ｔａ（２０）
【０１８６】
基板上のＴａ（３）／Ｃｕ（５０）／Ｔａ（３）は下部電極であり、Ｐｔ−Ｍｎ（２５）は反強磁性層からなる磁化安定層である。このＰｔ−Ｍｎ層に隣接するＮｉＦｅＣｒ（４）は粒径制御層である。また、基板から最も遠いＴａ（２０）は保護層（上部電極の一部を兼ねている）である。なお、Ｐｔ−Ｍｎ層、Ｎｉ−Ｆｅ−Ｃｒ層、Ｃｏ−Ｆｅ層およびＮｉ−Ｆｅ層の組成は、それぞれＰｔ_４９Ｍｎ_５１、Ｎｉ_６０Ｆｅ_１５Ｃｒ_２５、Ｃｏ_５０Ｆｅ_５０、Ｎｉ_８０Ｆｅ_２０であった。
【０１８７】
各サンプルとも実施例１と同様に成膜、上部電極の形成を行った後、２８０℃、５ｋＯｅ（４．０×１０^５Ａ／ｍ）の磁場中で５時間熱処理し、Ｐｔ−Ｍｎ層に磁界異方性を付与した。なお、サンプルの素子サイズは、いずれも０．５μｍ×１μｍとした。
【０１８８】
サンプルｅ１におけるＰｔ−Ｍｎ（２５）に接するＣｏ−Ｆｅ−Ｂ（１）は、微結晶体あるいはアモルファス体を多く含む磁性層の一例である。
【０１８９】
上記のようにして準備した各サンプルに対し、磁化安定層の平均粒径Ｄを測定した後、熱処理を加えた場合のＭＲ特性の変化（ＭＲ特性の熱処理温度依存性）を調べた。まず、無磁界、水素雰囲気下において各サンプルを熱処理温度（４００℃）にまで加熱し、３０分保持した後に、室温まで冷却し、ＭＲ特性としてＭＲ比を求めた。
【０１９０】
従来例であるサンプルｅ０において、熱処理前のＭＲ比は４５％以上であったが、４００℃の熱処理によって素子のＭＲ特性は大きく劣化し、熱処理後に得られるＭＲ比は０％であった。サンプルｅ０について、同じ膜構成のサンプルを１５個準備して同様の測定を行ったが、すべて同じ結果となった。なお、サンプルｄ０の磁化安定層の平均粒径Ｄは、０．５〜２．５ｎｍであった。
【０１９１】
それに対して、サンプルｅ１では、熱処理によって素子のＭＲ特性が大きく劣化することはなく、４００℃の熱処理を経た後も２０％以上のＭＲ比を得ることができた。
【０１９２】
サンプルｅ１のように、磁化安定層と非磁性層との間に、Ｃｏ−Ｆｅ−Ｂ層のように、微結晶あるいはアモルファスを主構造とする層を少なくとも１層配置することで、磁化安定層に含まれる拡散元素種の拡散防止に効果があると考えられる。このことは、拡散元素がある程度、各層の粒界周辺を拡散経路としてしていることを示唆しており、微結晶あるいはアモルファスを主構造とする層によって拡散経路が分断された効果が出ているのではないかと推察される。なお、ここで主構造とは、層の約５０ｖｏｌ％以上を占める構造のことであり、微結晶とは、少なくとも１μｍ径以下の結晶が、一方向に配向せずに、分散した状態のことを意味している。
【０１９３】
なお、本実施例ではＣｏ−Ｆｅ−Ｂ層を用いた例を示したが、その他、Ｃｏ−Ｆｅ−Ｂと同様に、微結晶あるいはアモルファスとして安定であるＮｉ−Ｆｅ−Ｂを用いても同様な結果が得られた。
【０１９４】
（実施例６）
実施例１で作製したサンプルａ０と、実施例３で作製したサンプルｃ３とを用い、図１７に示すようなシールドを備えた磁気ヘッドを作製し、その特性を評価した。ただし、本実施例では、サンプルｃ３の磁化安定層である反強磁性層Ｉｒ−Ｍｎ（２５）の代わりにＰｔ−Ｍｎ（２５）（組成はＰｔ_４９Ｍｎ_５１）を用い、Ｍ−Ｘ層としてＦｅ−Ｐｔ層（組成はＦｅ_８５Ｐｔ_１５）を用いた。
【０１９５】
磁気ヘッドの基板としてＡｌ_２Ｏ_３−ＴｉＣ基板を用い、上部記録コア、上部シールドおよび下部シールドとして組成がＮｉ_８０Ｆｅ_２０であるＮｉ−Ｆｅ合金を用いた。また、ＭＲ素子を狭持する電極として、Ａｕの積層膜を用い、絶縁膜にはＡｌ_２Ｏ_３を用いた。
【０１９６】
また、ＭＲ素子には、自由磁性層にあたる磁性層（Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３））の磁化容易方向が検知すべき信号磁界方向と垂直になるように、固定磁性層にあたる磁性層（Ｐｔ−Ｍｎ（２５）／Ｆｅ−Ｐｔ（２）／Ｃｏ−Ｆｅ（１）／Ｒｕ（０．７）／Ｃｏ−Ｆｅ（３））の磁化方向が検知すべき信号磁界方向と平行になるように異方性を付与した。この異方性の付与は、ＭＲ素子を実施例１と同様に作製後、まず、３００℃、５ｋＯｅ（４．０×１０^５Ａ／ｍ）の磁界中熱処理を行うことで固定磁性層の磁化方向を規定した後、２００℃、１０ｋＯｅ（８．０×１０^５Ａ／ｍ）の磁界中熱処理を行い、自由磁性層の磁化容易方向を規定することで行った。
【０１９７】
なお、再生部のＭＲ素子のトラック幅は０．１μｍ、ＭＲ高さも０．１μｍとした。
【０１９８】
上記のように作製した磁気ヘッドに対し熱処理（４００℃、真空中、３０分）を加えて特性評価を行った。センス電流として１Ａの直流電流を流し、５０Ｏｅ（４．０×１０^３Ａ／ｍ）の交流信号磁界を印加してヘッドの出力を評価したところ、ＭＲ素子として従来例であるサンプルａ０を用いた磁気ヘッドでは出力が得られなかったのに対し、サンプルｃ３を用いた磁気ヘッドでは、１５ｍＶ／μｍ以上の出力を得ることができた。
【０１９９】
また、ＭＲ素子としてサンプルｃ３を含む上記磁気ヘッドを用いて図１９に示すような磁気記録装置（ＨＤＤ）を作製したところ、１００Ｇｂｉｔ／ｉｎ^２以上の面記録密度を達成できた。さらに作製した磁気記録装置に対し、外部温度１５０℃、対応内部温度４００℃の環境試験（試験時間３０分）を行ったところ、上記の出力を維持しており、耐熱性に優れた磁気記録装置を得ることができた。
【０２００】
（実施例７）
実施例３で作製したサンプルｃ３を用い、図１８に示すようなヨークを備えた磁気ヘッドを作製し、その特性を評価した。ただし、本実施例では、サンプルｃ３の磁化安定層である反強磁性層Ｉｒ−Ｍｎ（２５）の代わりにＰｔ−Ｍｎ（２５）（組成はＰｔ_４９Ｍｎ_５１）を用い、Ｍ−Ｘ層としてＦｅ−Ｐｔ層（組成はＦｅ_８５Ｐｔ_１５）を用いた。
【０２０１】
ヨークには、組成がＮｉ_８０Ｆｅ_２０であるＮｉ−Ｆｅメッキ合金を用いた。本磁気ヘッドでは、ヨークであるＮｉ−Ｆｅ面をＣＭＰ研磨した後に、ＭＲ素子を形成し、最後にＡｕからなる電極膜を積層して作製した。再生ヘッド部のＭＲ素子の素子サイズは０．３μｍ×０．３μｍとした。
【０２０２】
ＭＲ素子には、実施例６と同様に、自由磁性層にあたる磁性層の磁化容易方向が検知すべき信号磁界方向と垂直になるように、固定磁性層にあたる磁性層の磁化方向が検知すべき信号磁界方向と平行になるように異方性を付与した。
【０２０３】
上記のように作製したヘッドに対し熱処理（４００℃、真空中、３０分）を加えて特性評価を行った。センス電流として１Ａの直流電流を流し、５０Ｏｅ（４．０×１０^３Ａ／ｍ）の交流信号磁界を印加してヘッドの出力を評価したところ、１０ｍＶ／μｍ以上の出力を得ることができた。
【０２０４】
（実施例８）
実施例３で作製したＭＲ素子（従来例ｃ０Ａおよび実施例ｃ３）を用いて、図２０に示すようなＭＲＡＭを作製した。ただし、サンプルｃ３のＭ−Ｘ層としてＦｅ−Ｐｔ層（組成はＦｅ_８５Ｐｔ_１５）を用いた。
【０２０５】
ＭＲＡＭの作製は以下のように行った。まず、３００ｎｍの熱酸化膜を有するＳｉ基板上に、Ｃｕからなるワード線を形成し、その表面にＡｌ_２Ｏ_３絶縁膜を成膜して形成した後、Ｃｕからなる下部電極を形成した。ここでいったんＣＭＰにより下部電極表面の平滑化を行った後、サンプルｃ０Ａおよびサンプルｃ３に示す膜構成のＭＲ素子を積層させた。
【０２０６】
次に、反強磁性層であるＩｒ−Ｍｎ層と固定磁性層とが交換結合磁界を生じるように、２８０℃、５ｋＯｅ（４．０×１０^５Ａ／ｍ）の磁界中熱処理を５時間行った。その後、実施例１と同様に、メサ型加工などを行って、ＭＲ素子を形成した。最後に、上部電極としてビット線を形成し、図２４に示すようなスイッチ素子を持たない単一磁気メモリを作製した。
【０２０７】
作製した磁気メモリに対し、ワード線とビット線に電流を流して磁界を発生させ、ＭＲ素子の自由磁性層（本実施例における、Ｃｏ−Ｆｅ（２）／Ｎｉ−Ｆｅ（３））の磁化方向を反転させて情報「０」を記録した。また、次に、ワード線とビット線に対して先程とは逆方向の電流を流して磁界を発生させ、自由磁性層を磁化反転させて情報「１」を記録した。その後、それぞれの状態のＭＲ素子に対してバイアス電圧を印加することでセンス電流を流し、情報「０」と情報「１」の状態における素子電圧の差を測定したところ、実施例、従来例ともに、同程度の出力差が得られた。よって、実施例、従来例ともに、自由磁性層を情報記録層とした磁気メモリとなっていることがわかった。
【０２０８】
次に、上記のＭＲ素子をＣＭＯＳ基板上に配置し、図２０に示すような集積磁気メモリを作製した。素子配列は、１６×１６素子のメモリを１ブロックとして、合計８ブロックとした。ＭＲ素子の配置は、次のように行った。まずＣＭＯＳ基板上に、スイッチ素子としてＦＥＴをマトリックス状に配置し、ＣＭＰで表面を平坦化した後、上記実施例ｃ３と従来例ｃ０ＡのＭＲ素子を、ＦＥＴに対応してマトリックス状に配置した。それぞれの素子サイズは０．２μｍ×０．３μｍとした。各ブロック中１素子は、配線抵抗や素子最低抵抗、ＦＥＴ抵抗などをキャンセルするためのダミー素子とした。なお、ワード線、ビット線などは全てＣｕを用いた。磁気メモリ形成後、水素シンター処理を４００℃にて行った。
【０２０９】
このように作製した磁気メモリに対し、ワード線とビット線の合成磁界により、各ブロックそれぞれ８素子の自由磁性層の磁化反転を同時に行い、信号を記録させた。次に、ＦＥＴのゲートを、それぞれのブロックに付き１素子づつＯＮし、素子にセンス電流を流した。このとき、各ブロック内でのビット線、素子およびＦＥＴに発生する電圧とダミー電圧とをコンパレータにより比較して、それぞれの素子の出力を読みとった。
【０２１０】
結果、実施例ｃ３のＭＲ素子を用いたＭＲＡＭでは、単一磁気メモリの場合と同様に良好な素子出力が得られたが、従来例ｃ０ＡのＭＲ素子を用いたＭＲＡＭでは、全く素子出力が得られなかった。このことから、従来例ｃ０ＡのＭＲ素子は、４００℃の熱処理に耐えられないのに対し、実施例ｃ３のＭＲ素子は、４００℃の熱処理に対しても十分な耐熱性を持っていることがわかる。
【０２１１】
【発明の効果】
以上説明したように、本発明によれば、磁化安定層の平均粒径と、磁化安定層と非磁性層との距離とを制御することにより、耐熱性に優れた高出力のＭＲ素子とすることができる。また、本発明のＭＲ素子を用いることで、耐熱性に優れた磁気ヘッドおよび磁気メモリ素子、ならびに磁気記録装置を得ることができる。
【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の例を示す断面図である。
【図２】本発明における磁気抵抗効果素子の例を示す断面図である。
【図３】本発明における磁気抵抗効果素子の例を示す断面図である。
【図４】本発明における磁気抵抗効果素子の例を示す断面図である。
【図５】本発明の磁気抵抗効果素子における結晶粒の状態の例を説明するための断面図である。
【図６】本発明における磁気抵抗効果素子の例を示す断面図である。
【図７】本発明における磁気抵抗効果素子の例を示す断面図である。
【図８】本発明における磁気抵抗効果素子の例を示す断面図である。
【図９】本発明における磁気抵抗効果素子の例を示す断面図である。
【図１０】本発明における磁気抵抗効果素子の例を示す断面図である。
【図１１】本発明における磁気抵抗効果素子の例を示す断面図である。
【図１２】本発明における磁気抵抗効果素子の例を示す断面図である。
【図１３】本発明における磁気抵抗効果素子の例を示す断面図である。
【図１４】本発明における磁気抵抗効果素子の例を示す断面図である。
【図１５】本発明における磁気抵抗効果素子の例を示す断面図である。
【図１６】電極をさらに配置した本発明における磁気抵抗効果素子の例を示す断面図である。
【図１７】本発明における磁気ヘッドの例を示す模式図である。
【図１８】本発明における磁気ヘッドの例を示す模式図である。
【図１９】本発明における磁気記録装置の例を示す模式図である。
【図２０】本発明における磁気メモリの例を示す模式図である。
【図２１】本発明における磁気メモリの例を示す模式図である。
【図２２】本発明における磁気メモリの動作の基本例を示す模式図である。
【図２３】本発明における磁気メモリの動作の基本例を示す模式図である。
【図２４】本発明における磁気メモリの動作の基本例を示す模式図である。
【図２５】実施例により測定した、熱処理温度とＭＲ比との関係を示す図である。
【図２６】実施例により測定した、磁化安定層表面の結晶粒の大きさを示す図である。
【図２７】実施例により測定した、粒径制御層の膜厚Ｘ_１と、ＭＲ比および平均粒径Ｄとの関係を示す図である。
【図２８】実施例により測定した、距離Ｈと、ＭＲ比および平均粒径Ｄとの関係を示す図である。
【図２９】実施例により測定した、距離Ｈと、ＭＲ比および平均粒径Ｄとの関係を示す図である。
【図３０】実施例により測定した、距離Ｈと平均粒径Ｄとの関係を示す図である。
【図３１】実施例により測定した、熱処理前後におけるＭＲ素子のマイナー曲線を示す図である。
【図３２】実施例により測定した、熱処理前後におけるＭＲ素子のマイナー曲線を示す図である。
【符号の説明】
１、１１、１２、１３　非磁性層
２、３、３１、３２　磁性層
４　磁化安定層
５　自由磁性層
６、６１、６２　固定磁性層
７　粒径制御層
８　拡散制御層
９　基板
４１　軟磁性層
４２　高保磁力磁性層
４３　反強磁性層
１０１　結晶粒
１０２　粒界
３０１　非磁性膜
３０２、３０３　磁性膜
３１０　積層フェリ層
５０１　層間絶縁膜
５０２　上部電極
５０３　下部電極
５０４　基板
５０５、５２０、５３１、６０１、６０１ａ、７０１　ＭＲ素子
５１１　ヘッド部
５１２　書き込みヘッド部
５１３　再生ヘッド部
５１４　コイル
５１５　上部記録コア
５１６　上部シールド
５１７　記録ギャップ
５２１　再生ギャップ
５２２　下部シールド
５２３　電極部
５３２　ヨーク
５４１　磁気ヘッド
５４２　駆動部
５４３　磁気記録媒体
５４４　信号処理部
５４５　磁気記録装置
６０２、７０３　ビット線
６０３　ワード線
６０４　結合線
７０５　スイッチ素子
７０６　非線形素子[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetoresistive element (hereinafter, referred to as “MR element”), and a magnetic device, a magnetic head, a magnetic memory, and a magnetic recording apparatus using the same. The MR element of the present invention is suitable for applications such as high-density magnetic recording / reproducing heads used for media such as magnetic disks, magneto-optical disks, and magnetic tapes, magnetic sensors used in automobiles, and magnetic random access memories. ing.
[0002]
[Prior art]
In recent years, development for applying a magnetoresistance effect (MR effect) based on a conduction phenomenon dependent on electron spin to a magnetic head, a magnetic memory (Magnetic Random Access Access Memory (MRAM)), and the like has been actively performed. The MR effect is a phenomenon in a multilayer film including a [magnetic layer / non-magnetic layer / magnetic layer] structure in which a resistance value differs depending on a relative angle of a magnetization direction between adjacent magnetic layers via the non-magnetic layer. . Generally, when the magnetization directions are parallel, the resistance value is the smallest, and when the magnetization directions are antiparallel, the resistance value is the largest. An element utilizing such an MR effect is called an MR element. Among the MR elements, those using a conductive material such as Cu as the nonmagnetic layer are called GMR elements. The GMR element includes a device that allows a current to flow in parallel to the film surface (CIP-GMR: Current In Plane-GMR) and a device that allows a current to flow perpendicular to the film surface (CPP-GMR: Current Perpendicular to to Plane-GMR). is there. In addition, Al is added to the non-magnetic layer.₂O₃An MR element using an insulating material such as this is called a TMR element. In the TMR element, a higher magnetoresistance ratio (MR ratio) can be obtained as the spin polarization of the magnetic layer sandwiching the nonmagnetic layer is higher. Materials having a large spin polarizability include magnetic metals such as Fe, magnetic metal alloys such as Co—Fe alloys and Ni—Fe alloys, and half-metallic ferromagnetic materials expected to have a spin polarizability of 100%. (Journal of the Japan Society of Applied Magnetics, Vol. 20, {No. 5} (1996), 896, Japan Society of Applied Magnetics, 112th Study Group, p11-17, etc.). At present, this TMR element is expected as an MR element exhibiting a large MR ratio.
[0003]
In order to use an MR element such as a GMR element or a TMR element as a device that operates with a small magnetic field, an MR element called a spin valve type has been proposed. In the spin-valve MR element, the magnetization direction of one magnetic layer (pinned magnetic layer) sandwiching the nonmagnetic layer is fixed by the exchange coupling magnetic field from the antiferromagnetic layer containing the antiferromagnetic material. On the other hand, since the magnetization direction of the other magnetic layer (free magnetic layer) can move freely with respect to an external magnetic field, the relative angle of the magnetization direction between the fixed magnetic layer and the free magnetic layer can be easily set. Can be changed. Such a spin-valve MR element has already been applied to a magnetic head in a GMR element. Along with the GMR element, a spin-valve MR element using a TMR element is also used in next-generation magnetic heads and high-density MRAMs. It is expected to be applied.
[0004]
[Problems to be solved by the invention]
However, in a conventional MR element using a magnetic metal such as Fe, Ni, or Co, or a magnetic metal alloy thereof for a magnetic layer, a high temperature (for example, 400 ° C. or higher) required when a device is formed into an MRAM or the like. (Y. Ando et. Al., Jpn. J. Appl. Phys., 39 (2000) 5832., S. Cardoso). et al., {J.} Appl. @ Phys., {89} (2001) @ 6650. It is considered that the deterioration of the MR characteristics is one of the causes of mutual diffusion of elements in the multilayer film constituting the element. In the future, as the density of magnetic heads and MRAMs increases, and the hybridization of the device process and the semiconductor process advances, a high-output MR element having better heat resistance is required. However, there has not been reported any MR element having excellent heat resistance that can maintain the characteristics even after the heat treatment at 400 ° C. or higher.
[0005]
Therefore, an object of the present invention is to provide a high-output MR element having better heat resistance than a conventional element. It is another object of the present invention to provide a magnetic head, a magnetic memory, and a magnetic recording device having excellent heat resistance.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the MR element of the present invention has a multilayer structure including a structure in which a pair of magnetic layers are stacked via a nonmagnetic layer formed on a substrate. A magnetoresistive element having a resistance value that varies depending on a relative angle of direction, further comprising a magnetization stable layer that changes a magnetization reversal magnetic field of the magnetic layer, wherein the magnetization stable layer satisfies a relationship represented by the following equation. And
[0007]
1 nm ≦ D <10 nm
And
D ≧ 2 × H or H ≧ 1.4 × D
Here, D is the average grain size of the crystal grains of the material constituting the magnetization stable layer, and H is the distance between the magnetization stable layer and the nonmagnetic layer.
[0008]
Further, in the MR element of the present invention, a multilayer structure including a structure in which a pair of magnetic layers is stacked via a non-magnetic layer is formed on a substrate, and the resistance is determined by the relative angle of the magnetization direction of both magnetic layers. A magnetoresistive element having a different value may further include a magnetization stable layer for changing a magnetization reversal magnetic field of the magnetic layer, and the magnetization stable layer may satisfy a relationship represented by the following equation.
[0009]
D ≧ 10 nm
Here, D is the average grain size of crystal grains of the material constituting the magnetization stable layer (hereinafter, referred to as the average grain size of the magnetization stable layer).
[0010]
As described above, by controlling the average grain size of the magnetization stable layer and / or the distance between the magnetization stable layer and the nonmagnetic layer, the diffusion of the elements contained in the magnetization stable layer is suppressed, and the heat stability is improved. The obtained MR element can be obtained.
[0011]
The MR element preferably further includes a grain size control layer for changing the grain size of crystal grains of the material contained in the magnetization stable layer. The grain size control layer changes the grain size, orientation, and the like of crystal grains of the material contained in the magnetization stable layer, and can suppress the diffusion of elements contained in the magnetization stable layer. In that case, it is preferable that the grain size control layer is disposed between the magnetization stable layer and the substrate. Further, it is preferable that the grain size control layer is arranged so as to be in contact with the magnetization stable layer.
[0012]
The MR element preferably further includes a diffusion control layer. The diffusion control layer can suppress the diffusion of the element contained in the magnetization stable layer. At this time, the diffusion control layer may be arranged between the magnetization stable layer and the substrate, or may be arranged between the magnetization stable layer and the nonmagnetic layer. Further, it is preferable that the diffusion control layer is disposed so as to be in contact with the magnetization stable layer.
[0013]
A magnetic head according to another aspect of the invention includes the MR element described above and a shield that restricts introduction of a magnetic field other than a magnetic field to be detected by the MR element into the element. Further, the magnetic head of the present invention may have a structure including the MR element and a yoke for introducing a magnetic field to be detected into the MR element. A magnetic recording device according to the present invention includes the above-described magnetic head.
[0014]
With the above structure, a magnetic head and a magnetic recording device having excellent heat resistance can be obtained.
[0015]
A magnetic memory according to the present invention includes the above-described MR element, an information recording conductor line for recording information on the MR element, and an information reading conductor line for reading the information. And
[0016]
With the above structure, a magnetic memory having excellent heat resistance can be obtained.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
First, an MR element according to the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a sectional view showing an example of an MR element according to the present invention. In the example shown in FIG. 1, the magnetization stable layer 4, the magnetic layer 3, the nonmagnetic layer 1, and the magnetic layer 2 are sequentially stacked from the substrate 9 side. In this element, by arranging the magnetization stabilizing layer 4 between the substrate 9 and the magnetic layer 3, the magnetization reversal magnetic field of the magnetic layer 3 can be increased or decreased relatively to the magnetic layer 2. Can be. Therefore, the parallel and antiparallel of the magnetization directions of both magnetic layers become clear, and an MR element with stable output can be obtained.
[0019]
In the example shown in FIG. 1, the magnetization stable layer 4 is disposed between the substrate 9 and the magnetic layer 3, but the magnetization stable layer can be disposed on the magnetic layer 2. In this case, the magnetization reversal magnetic field of the magnetic layer 2 can be changed relative to the magnetic layer 3.
[0020]
FIG. 2 shows an example in which a soft magnetic layer is used as the magnetization stable layer in the MR element shown in FIG. In the example shown in FIG. 2, the soft magnetic layer 41 is laminated between the substrate 9 and the magnetic layer 3, and the magnetization rotation of the magnetic layer 3 is relatively easier than that of the magnetic layer 2. Therefore, an MR element in which the magnetic layer 3 and the soft magnetic layer 41 are the free magnetic layer 5 and the magnetic layer 2 is the fixed magnetic layer 6 can be obtained.
[0021]
The material used for the soft magnetic layer is not particularly limited as long as the material has excellent soft magnetic characteristics._pCo_qFe_rCan be used. p, q, and r are adjusted according to required characteristics in the range of 0 ≦ p ≦ 1, 0 ≦ q ≦ 1, 0 ≦ r ≦ 1, and p + q + r = 1.
[0022]
Above all, as metal A, the range represented by 0.6 ≦ p ≦ 0.9, 0 ≦ q ≦ 0.4, 0 ≦ r ≦ 0.3, or 0 ≦ p ≦ 0.4, 0.2 Those in the ranges represented by ≦ q ≦ 0.95 and 0 ≦ r ≦ 0.5 are preferable.
[0023]
FIG. 3 shows an example in which a high coercive force magnetic layer is used as the magnetization stable layer in the MR element shown in FIG. By arranging the high coercive force magnetic layer 42 between the magnetic layer 3 and the substrate 9, the magnetic layer 3 has a larger coercive force than the magnetic layer 2 and the magnetization rotation is relatively unlikely to occur. Therefore, in the example shown in FIG. 3, the MR element is such that the magnetic layer 2 is the free magnetic layer 5, and the magnetic layer 3 and the high coercive force magnetic layer 42 are the fixed magnetic layer 6.
[0024]
As a material used for the high coercive force magnetic layer, the coercive force is 100 Oe (8 × 10³A / m) or more materials, for example, Co-Pt, Co-Cr-Pt, Co-Ta-Pt, Co-Sm, and Fe-Tb are preferable.
[0025]
FIG. 4 shows an example in which an antiferromagnetic layer is used as the magnetization stable layer in the MR element shown in FIG. As shown in FIG. 4, when the antiferromagnetic layer 43 is stacked between the magnetic layer 3 and the substrate 9, an exchange bias magnetic field acts between the antiferromagnetic layer 43 and the magnetic layer 3 so that the magnetic layer 3 Since the magnetization direction of the magnetic layer 3 exhibits magnetic anisotropy, the switching field of the magnetic layer 3 can be increased. Therefore, a spin-valve MR element in which the magnetic layer 3 and the magnetization stable layer 43 are the fixed magnetic layer 6 and the magnetic layer 2 is the free magnetic layer 5 can be obtained.
[0026]
When an antiferromagnetic layer is used as the magnetization stabilizing layer, the leakage magnetic field generated from the end of the magnetic body can be reduced, and an MR element having a smaller shift magnetic field in the magnetic field-magnetization characteristics can be obtained.
[0027]
As a material for the antiferromagnetic layer, an antiferromagnetic material containing Mn (Mn-based antiferromagnetic alloy) is preferable because it has excellent thermal stability of magnetic properties. Above all, a composition represented by the formula Mn-Z (where Z is at least one element selected from Pt, Pd, Fe, Ir, Ni, Co, Rh, O, C, F, N and B) Is preferred.
[0028]
In the MR element including the above-described magnetization stable layer, elements included in the magnetization stable layer may be diffused at the time of heat treatment at a high temperature or the like, and may deteriorate the MR characteristics of the element. Among them, some elements, such as Mn, Ru, and Cu, which are often used in the element, are liable to interdiffusion, and are likely to further deteriorate the characteristics of the element. Further, when the diffusion of the above-mentioned element reaches the inside of the non-magnetic layer, it is considered that the MR characteristics of the element are particularly deteriorated.
[0029]
Each layer of the MR element as shown in FIGS. 1 to 4 is actually composed of a plurality of crystal grains 101 as shown in FIGS. It is considered that the above-described diffusion of the elements is performed not only between the interfaces of the respective layers but also along the grain boundaries 102 of the crystal grains 101. In general, it can be said that diffusion of elements along grain boundaries of crystal grains is more likely to occur than diffusion of elements between interfaces of each layer.
[0030]
Therefore, in the present invention, in order to reduce the MR characteristics of the element due to the diffusion of elements contained in each layer constituting the MR element at a high temperature, the average grain size of the magnetization stable layer The distance between the layers was controlled.
[0031]
It is preferable that the following relationship is established between the average grain size D of the magnetization stable layer 4 and the distance H between the nonmagnetic layer 1 and the magnetization stable layer 4 shown in FIGS. 5A and 5B. Note that the average grain size D of the magnetization stable layer in the present invention is not strictly the size itself of the crystal grain 101 in the direction parallel to each layer constituting the element as schematically shown in FIG. The measurement method will be described later in Examples.
[0032]
-The average particle diameter D is 10 nm or more.
Or
An average particle diameter D is 1 nm or more and less than 10 nm,
D and H are
H = 1.4 × D or D ≧ 2 × H
Meets.
[0033]
The above relationship means that the average grain size of the magnetization stable layer is large or that the distance between the magnetization stable layer and the nonmagnetic layer is preferably larger than a specific distance determined by the average grain size. I have. When such conditions are satisfied, it is possible to obtain an MR element with little deterioration in MR characteristics even during heat treatment at a high temperature and excellent in heat resistance.
[0034]
In addition, when an element area (here, “element area” means an area when the element is viewed from the thickness direction of each layer) is W, a relation satisfying W ≦ 25 × D is particularly satisfied. preferable. When this condition is satisfied, an MR element having more excellent heat resistance can be obtained.
[0035]
As shown in FIG. 5A, the grain boundaries 102 of crystal grains are likely to be formed continuously over a plurality of layers. However, as shown in FIG. When a film having a continuous and independent structure is formed, diffusion of elements along the grain boundaries 102 is suppressed, so that an MR element having more excellent heat resistance can be obtained.
[0036]
Further, as shown in FIG. 6, it is preferable to further arrange a grain size control layer 7 between the magnetization stable layer 4 and the substrate 9 of the MR element shown in FIG. By further disposing the grain size control layer 7, the average grain size of the crystal grains of the magnetization stable layer 4 and the orientation of the crystal structure can be controlled, and a stable MR element having more excellent heat resistance can be obtained. it can.
[0037]
As a material used for the particle size control layer 7, an alloy material containing at least one element selected from Ta, Nb, Hf, Zr and Cr, or an alloy such as Ni-Fe and Ni-Fe-Cr is preferable. In particular, when Ni—Fe—Cr is used, it is possible to control not only the magnetization stable layer 4 but also the crystal orientation of the magnetic layer 3 and, in some cases, the nonmagnetic layer 1, and is excellent in heat resistance and high output. An MR element can be obtained.
[0038]
In the case where the Mn-based antiferromagnetic alloy is included as the magnetization stable layer, it is particularly preferable to arrange the grain size control layer so as to be in contact with the magnetization stable layer.
[0039]
Further, as shown in FIG. 7, it is preferable to further add a diffusion control layer 8 between the magnetization stable layer 4 and the substrate 9 of the MR element shown in FIG. By further adding the diffusion control layer 8, the diffusion of the element contained in the magnetization stable layer 4 into the magnetic layer 3 and the non-magnetic layer 1 can be suppressed.
[0040]
As a material used for the diffusion control layer 8, a material containing a ferromagnetic material having a composition represented by the formula MX (hereinafter, referred to as a ferromagnetic material MX) is preferable. Here, M is at least one kind of magnetic element selected from Fe, Co and Ni, and X is a group IVa to VII.
a group, VIII group, Ib group, lanthanoid, Al, Si, Sc, Y, Zn, Ga, Ge, B, C, N
, O, P and S are at least one non-magnetic element. Among them, the nonmagnetic element X is composed of Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, Al, Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Hf, Ta. , W, Re, Ga, Ge, lanthanoid, Si, B, C, N, O, P and S.
[0041]
When a material containing the ferromagnetic material MX is used as the diffusion control layer, not only the effect of suppressing the diffusion of the element but also the role as a normal magnetic layer can be taken, so that better MR characteristics can be obtained. Can be obtained.
[0042]
As shown in FIG. 8, a diffusion control layer 8 can be arranged between the nonmagnetic layer 1 and the magnetization stable layer 4 of the MR element shown in FIG. 4, the diffusion control layer 8 is disposed between the magnetic layer 3 and the non-magnetic layer 1). In this case, not only can the diffusion of the elements contained in the magnetization stable layer 4 be suppressed, but also the distance between the magnetization stable layer 4 and the nonmagnetic layer 1 can be increased.
[0043]
Further, as shown in FIG. 9, the diffusion control layer 8 is added to both the region between the magnetization stable layer 4 and the substrate 9 and between the magnetization stable layer 4 and the magnetic layer 3 of the MR element shown in FIG. Can also. In the case where a Mn-based antiferromagnetic alloy is included as the magnetization stabilizing layer, it is more preferable to arrange the diffusion control layer 8 in this manner.
[0044]
Further, as shown in FIG. 10, the MR element may include the diffusion control layer 8 and the grain size control layer 7 at the same time. Diffusion of the elements contained in the magnetization stable layer 4 can be further suppressed as compared with the case where only one of the diffusion control layer and the grain size control layer is included, and an MR element having more excellent heat resistance can be obtained. .
[0045]
The composition of the ferromagnetic material MX is expressed by the formula_100-aX_aIn this case, a is preferably a numerical value satisfying 0.05 ≦ a ≦ 60. Note that all numerical values used for indicating compositions in this specification are based on atomic% (at%).
[0046]
Preferred nonmagnetic elements X include the following X¹, X²And X³If the MR element is used in an appropriate range set according to the type, an MR element having more excellent MR characteristics can be obtained.
[0047]
X¹Is at least one element selected from Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt and Au;²Is at least one element selected from Al, Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Hf, Ta, W, Re, Ga, Ge and a lanthanoid;³Is at least one element selected from Si, B, C, N, O, P and S.
[0048]
X¹Is a platinum group element (Ru, Rh, Pd, Os, Ir, Pt) having more shell electrons (d electrons) than Fe, and Cu, Ag, and Au having 10 d electrons. In particular, the platinum group element has a property of exhibiting remarkable magnetism when added to the magnetic element M, and can increase the spin polarizability of the ferromagnetic material MX as compared with the case where another element is used. Therefore, an MR element having good MR characteristics can be obtained, and a solid solution can be easily formed with a diffusion element such as Mn, so that deterioration of the MR characteristics can be suppressed.
[0049]
X²Is a part of the transition metal element in which the number of shell electrons is less than Fe. Even when these elements are added to the magnetic element M, the spin polarizability of the ferromagnetic material MX can be increased. Although the same effect is expected when Cd and Hg are used, the description is omitted in this specification from the viewpoint of environmental problems.
[0050]
X³Is a nonmetallic element, and when these elements are added to the magnetic element M, the ferromagnetic material MX can be microcrystallized or made amorphous. In this case, since the structure of the crystal grain boundary of the diffusion control layer changes, the thermal diffusion of the elements contained in the magnetization stable layer can be suppressed.
[0051]
The composition of the ferromagnetic material MX is X¹, X²And X³Using the formula M_100-a(X¹ _bX² _cX³ _d)_aCan also be indicated by In this case, it is preferable that a, b, c and d are numerical values satisfying 0.05 ≦ a ≦ 60, 0 ≦ b ≦ 60, 0 ≦ c ≦ 30, 0 ≦ d ≦ 20, and a = b + c + d.
[0052]
As the magnetic element M, the formula Fe_1-stCo_sNi_tIt is preferable to use an element represented by Therefore, the ferromagnetic material MX has the formula (Fe_1-stCo_sNi_t)_100-a(X¹ _bX² _cX³ _d)_aCan also be shown. s and t are adjusted in the range of 0 ≦ s ≦ 1, 0 ≦ t ≦ 1, and s + t ≦ 1.
[0053]
When the magnetic element M is a ternary system (0 <s <1, 0 <t <1, s + t <1), s and t are preferably 0 <s <1, 0 <t ≦ 0.9, respectively. . Further, 0 <s <1 and 0 <t ≦ 0.65 are more preferable.
[0054]
When the magnetic element M is a binary system of Fe and Ni (s = 0, 0 <t <1), t is preferably 0 <t ≦ 0.95. When the magnetic element M is a binary system of Fe and Co (t = 0, 0 <s <1), s is preferably in the range of 0 <s ≦ 0.95.
[0055]
In order to obtain more excellent MR characteristics irrespective of the magnetic element M, X is preferably at least one element selected from V, Cr, Mn, Ru, Rh, Pd, Re, Os, Ir and Pt. . Further, at least two kinds of elements selected from the above element group can be used.
[0056]
When X is composed of one element, X is preferably one element selected from Pt, Pd, Pd, Rh and Ir. At this time, a is preferably in the range of 0.05 or more and 50 or less.
[0057]
When Pt is used as X, M is represented by the formula Fe_1-tNi_tWhen M has the composition represented by the formula, t is within the range of 0 <t ≦ 0.9 and M is represented by the formula Fe_1-sCo_sWhen the composition has the composition represented by the formula, s may be limited within the range of 0 <s ≦ 0.9. Further, the magnetic element M may be a one-component system composed of Fe.
[0058]
When X is composed of two elements, a combination of Pt and Re, Pt and Pd, or a combination of Rh and Ir is preferable.
[0059]
X is the formula Pt_bRe_cIn the case of having the composition represented by the following formula, a, b and c are preferably numerical values satisfying the following formula.
[0060]
0 <b <50, 0 <c ≦ 20, a = b + c, 0.05 ≦ a ≦ 50
X is the formula Pt_b1Pd_b2Or the formula Rh_b1Ir_b2When having a composition represented by the following, a, b₁And b₂Is preferably a numerical value satisfying the following expression.
[0061]
0 <b₁<50, 0 <b₂<50, a = b₁+ B₂, 0.05 ≦ a ≦ 50
The ferromagnetic material MX may have a composition gradient in the thickness direction of the diffusion control layer. The details of the composition gradient are not particularly limited. The ratio between the magnetic element M and the nonmagnetic element X may monotonously decrease or increase in the thickness direction, or may change periodically.
[0062]
When the ferromagnetic material MX has a crystal structure different from the crystal structure that the magnetic element M preferentially takes at normal temperature and normal pressure, the spin polarizability of the ferromagnetic material MX increases and good MR characteristics are obtained. May be obtained. Note that it is preferable that at least one selected from fcc, fct, bcc, bct, hcp, and hct is included as a different crystal structure.
[0063]
Fe easily forms a bcc structure, but by adding an element (for example, Pt, Pd, Rh, Ir, Cu, Au, or Ag) that easily forms an fcc structure, an Fe-Pt material containing Fe having an fcc structure is obtained. be able to. Further, by adding an element (for example, Cr, Nb, Mo, Ta, W, Eu, etc.) that easily takes a bcc structure to a Ni—Fe alloy having a fcc structure, a Ni—Fe—Cr material containing a bcc structure is obtained. Can be obtained. Alternatively, a Co-Pd material containing the fcc structure can be obtained by adding Pd having the fcc structure to Co, which easily takes the hcp structure.
[0064]
The ferromagnetic material MX may be a mixed crystal having two or more crystal structures, for example, a mixed crystal having at least two crystal structures selected from fcc, fct, bcc, bct, hcp and hct. Is also good. Further, the ferromagnetic material MX may have a structure of a phase boundary region between fcc and bcc, or fcc and hcp, for example.
[0065]
Although it is not clear why the spin polarizability increases due to the change in the crystal structure, invar alloys (for example, Fe-Pt, Fe-Pd, Fe-Co-Cr, Fe-Ni-Cr, Fe-Ni-Mn, Fe -Ni-V, Fe-Pt-Ir, Fe-Pt-Re, Fe-Pt-Ni, Fe-Ni-Cu, etc., which are included in the ferromagnetic material MX in the present invention). As described above, the relationship between the magnetic spin and the electronic structure and the crystal structure may influence.
[0066]
In the magnetization stable layer containing a Mn-based antiferromagnetic alloy, a crystal having a relatively high Mn content (crystal A) and a crystal having a relatively low Mn content may be obtained depending on a manufacturing method or a heat treatment process after lamination. A mixed crystal with (B crystal) may occur. When the mixed crystal occurs, the A crystal tends to be formed easily around the grain boundary portion.
[0067]
At this time, when the Mn content of the crystal A is 60 at% or more in atomic percentage, the volume ratio of the crystal A is preferably 25 vol% or less of the magnetization stable layer. It is possible to obtain an MR element with less deterioration in MR characteristics even at the time of high-temperature heat treatment and more excellent heat resistance.
[0068]
In the MR element of the present invention, the non-magnetic layer may be a non-magnetic layer made of a conductive material or a non-magnetic layer made of an insulating material. , TMR).
[0069]
When a conductive material is used for the nonmagnetic layer, it is preferable to use at least one element selected from Cu, Au, Ag, Ru, and Cr. At this time, a single film of the above element or an alloy film may be used. By using the non-magnetic layer as described above, an MR element that can realize a relatively low junction resistance can be obtained.
[0070]
When an insulating material is used as the non-magnetic layer (the non-magnetic layer is a tunnel insulating layer), the material is not particularly limited as long as it is an insulator or a semiconductor, but may be Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, La, Ce, Zn, B, Al, Ga, Si, lanthanoids, IIa to VIa groups and
And at least one element selected from the group consisting of Fb, O, C, N and B
It is preferable to use a compound with at least one element selected from In particular, Al oxides, nitrides, or oxynitrides are preferable because they have excellent insulating properties, can be formed into a thin film, and have excellent reproducibility.
[0071]
Further, in the MR element of the present invention, as shown in FIG. 11, the magnetic layer 3 of the MR element shown in FIG. 1 may have a structure in which magnetic films 302 and 303 are laminated on both surfaces of a non-magnetic film 301. Good. In the above laminated structure, by setting the thickness of the non-magnetic film 301 to an appropriate value (for example, 0.2 to 1.2 nm when Ru is used as the non-magnetic film), the magnetic film 302 and the magnetic film 303 can be formed. , An antiferromagnetic exchange coupling can be generated.
[0072]
In order to generate antiferromagnetic exchange coupling between the magnetic film 302 and the magnetic film 303, the material of the nonmagnetic film 301 is selected from Cr, Cu, Ag, Au, Ru, Ir, Re, and Os. It is preferable to include at least one element. Alternatively, a single film or a stacked film including an alloy or an oxide containing the above element can be used. At this time, the thickness of the nonmagnetic film 301 is preferably 0.2 to 1.2 nm.
[0073]
Thus, a multilayer film structure in which a pair of magnetic films are stacked via a non-magnetic film and antiferromagnetic exchange coupling occurs between the magnetic films is referred to as a stacked ferrimagnetic structure (stacked ferrilayer). By using the MR element including the laminated ferri-layer, the demagnetizing field of the free magnetic layer can be kept small and the magnetic field response can be improved even when the element size is miniaturized.
[0074]
Further, by adjusting the thickness of the nonmagnetic film 301, magnetostatic coupling can be generated between the magnetic film 302 and the magnetic film 303. In order to generate magnetostatic coupling between the magnetic film 302 and the magnetic film 303, the material of the non-magnetic film 301 is not particularly limited as long as it is a non-magnetic material, but its thickness needs to be 2 nm or more. is there.
[0075]
Regardless of whether the laminated structure of the non-magnetic film 301 and the magnetic films 302 and 303 is a laminated ferri structure (a laminated ferri layer) or a magnetostatic coupling structure (a magnetostatic coupling layer), the magnetic films 302 and 303 When a hard magnetic material having a large saturation magnetization such as Co—Fe is used, the magnetization reversal magnetic field of the magnetic layer 3 can be made relatively larger than that of the magnetic layer 2, and the magnetic layer 3 and the magnetization stable layer 4 are fixed. An MR element in which the magnetic layer and the magnetic layer 2 are free magnetic layers can be obtained. In addition, when the above-mentioned laminated structure is a laminated ferri structure, it is generally called “a laminated ferri pinned layer”.
[0076]
On the other hand, regardless of whether the laminated structure of the nonmagnetic film 301 and the magnetic films 302 and 303 has a laminated ferrimagnetic structure or a magnetostatic coupling structure, the magnetic films 302 and 303 have a saturation magnetization of Ni—Fe or the like. When a soft magnetic material having a small magnetic field is used, the magnetization reversal magnetic field of the magnetic layer 3 can be made relatively smaller than that of the magnetic layer 2, and the magnetic layer 3 and the magnetization stable layer 4 are free magnetic layers, and the magnetic layer 2 is a fixed magnetic layer. It can be a layered MR element. When the laminated structure is a laminated ferri structure, it is generally called a “laminated ferri free layer”.
[0077]
In the example shown in FIG. 11, only the magnetic layer 3 has a laminated structure of the nonmagnetic film 301 and the magnetic films 302 and 303. However, even if the magnetic layer 2 has the above laminated structure. I do not care. For example, if the magnetic layer 2 includes a laminated ferrimagnetic free layer, a free magnetic layer having more excellent soft magnetic properties can be obtained. Further, if necessary, the magnetic layer 3 (and the magnetic layer 2) may include a magnetic film other than the above-mentioned laminated structure.
[0078]
In addition, as shown in FIG. 12, when the antiferromagnetic layer 43 is used as the magnetization stabilizing layer of the MR element shown in FIG. 11, it is possible to make the MR element have a higher bias magnetic field. In the example shown in FIG. 12, the laminated ferrilayer 310 and the antiferromagnetic layer 43 are a fixed magnetic layer, and the magnetic layer 2 is a free magnetic layer. In the example shown in FIG. 12, the antiferromagnetic layer 43 and the laminated ferrilayer 310 are in contact with each other, but another layer such as a magnetic film may be further arranged between them, if necessary. Further, the laminated ferrilayer 310 may be the above-described magnetostatic coupling layer.
[0079]
Further, as shown in FIG. 13, the MR element according to the present invention has a dual spin structure in which fixed magnetic layers 61 and 62 are arranged on both sides of a magnetic layer 2 which is a free magnetic layer 5 with nonmagnetic layers 11 and 12 interposed therebetween. An element having a valve structure may be used. In the example shown in FIG. 13, the fixed magnetic layer 61 includes the magnetic layer 31 and the antiferromagnetic layer 431, and the fixed magnetic layer 62 includes the magnetic layer 32 and the antiferromagnetic layer 432. Here, by including antiferromagnetic layers 431 and 432, the magnetization directions of fixed magnetic layers 61 and 62 are fixed. As shown in FIG. 14, fixed magnetic layers 61 and 62 may further include laminated ferrimagnetic layers 311 and 312.
[0080]
By having such a dual spin valve structure, for example, in a GMR element in which the nonmagnetic layers 11 and 12 are made of a conductive material, the number of magnetic layer / nonmagnetic layer interfaces where electrons are magnetically scattered increases. A larger MR ratio can be obtained. In a TMR element in which the nonmagnetic layers 11 and 12 are made of an insulating material, the MR ratio does not change much, but has two barriers, so that the bias voltage dependency can be improved. Further, the laminated ferrimagnetic layers 311 and 312 may be the magnetostatic coupling layers described above.
[0081]
In the examples shown in FIGS. 13 and 14, the free magnetic layer 5 can also include a laminated ferrilayer (a laminated ferrifree layer). In this case, the soft magnetic characteristics of the free magnetic layer 5 can be improved.
[0082]
Further, in the MR element according to the present invention, a nonmagnetic layer 13 may be further laminated on the free magnetic layer 5 as shown in FIG. The example shown in FIG. 15 is an element in which a nonmagnetic layer 13 is further added on the magnetic layer 2 which is the free magnetic layer 5 of the MR element shown in FIG.
[0083]
By laminating the non-magnetic layer 13, for example, in the CIP-GMR element, the non-magnetic layer 13 becomes a reflection layer of electrons, and the MR characteristics can be improved. In the CPP-GMR element and the TMR element, electrons flowing in the element can be obtained. Contains higher energy than the Fermi level, so that the output of the device can be increased and the bias voltage dependency can be improved.
[0084]
Next, a method for manufacturing an MR element according to the present invention will be described.
[0085]
For forming each thin film constituting the MR element, pulse laser deposition (PLD), ion beam deposition (IBD), cluster ion beam, RF, DC, ECR, helicon, inductively coupled plasma (ICP), facing target Such as sputtering, MBE, and ion plating. In addition to the PVD method, a CVD method, a plating method, a sol-gel method, or the like can be used.
[0086]
An example in which the ferromagnetic material MX of the present invention is manufactured using the sputtering method will be described. Various procedures are conceivable. For example, a pellet made of X is placed on an alloy target made of M to form a film by sputtering, or a target made of M and a target made of X are formed by sputtering at the same time. You may. Alternatively, a target made of M and a target made of X are alternately stacked in advance, and a sputter film is formed, or a part of X is introduced into the apparatus in a gas state, and then reactive sputtering is performed. Can also be formed into a film.
[0087]
When a tunnel insulating layer is formed as a non-magnetic layer, for example, a thin film precursor of Al is formed and an atmosphere containing any of F, O, C, N, and B as molecules, ions, radicals, or the like, The above-mentioned thin film precursor may be reacted with any of F, O, C, N and B while controlling the temperature and time. The thin film precursor is almost completely fluorinated, oxidized, carbonized, nitrided or borated to obtain a tunnel insulating layer. Further, as a thin film precursor, a nonstoichiometric compound containing any of F, O, C, N and B at a stoichiometric ratio or less is prepared, and any of F, O, C, N and B is converted into a molecule, an ion The reaction may be performed while controlling the temperature and the time in an atmosphere containing as radicals. The same applies to the case where an element other than Al is used.
[0088]
For example, using a sputtering method,₂O₃When producing a tunnel insulating layer made of Al or AlO_x(X ≦ 1.5) is replaced by Ar or Ar + O₂A film is formed in an atmosphere,₂Or O₂Oxidation in an inert gas may be repeated. Note that plasma or radicals may be produced by using ordinary means such as ECR discharge, glow discharge, RF discharge, helicon, and inductively coupled plasma (ICP).
[0089]
Hereinafter, a device using an MR element according to the present invention will be described.
[0090]
In order to fabricate a magnetic device including an MR element that allows a current to flow in the direction perpendicular to the film surface, physical methods such as ion milling, RIE, and FIB, which are generally used in semiconductor processes and GMR head fabrication processes, are used. Alternatively, fine processing may be performed by a combination of a photolithography technique using a chemical etching method, a stepper for forming a fine pattern, an EB method, or the like.
[0091]
FIG. 16 shows an example of an MR element manufactured by such a method. In the element shown in FIG. 16, a lower electrode 503, an MR element 505, and an upper electrode 502 are sequentially stacked on a substrate 504, and an interlayer insulating film 501 is arranged between electrodes around the MR element 505. The interlayer insulating film 501 has a function of preventing an electrical short circuit between the upper electrode 502 and the lower electrode 503. In this element, a current is applied to an MR element 505 sandwiched between an upper electrode 502 and a lower electrode 503 to read a voltage. With such an element configuration, an output can be read by flowing a current in a direction perpendicular to the film surface of the MR element 505. Note that CMP, cluster ion beam etching, or the like can be used to planarize the surface of an electrode or the like.
[0092]
As a material of the electrodes 502 and 503, a low-resistance material (resistivity of 100 μΩcm or less) such as Pt, Au, Cu, Ru, Al, and TiN may be used. As the interlayer insulating film 501, Al₂O₃, SiO₂For example, a material having an excellent insulating property such as an insulating material may be used.
[0093]
FIG. 17 shows an example of a magnetic head using an MR element according to the present invention. FIG. 17 is a sectional view showing a shield type magnetic head provided with a shield for restricting introduction of a magnetic field other than the magnetic field to be detected by the MR element into the MR element.
[0094]
In the example shown in FIG. 17, the head unit 511 includes a write head unit 512 for recording and a reproduction head unit 513 for reproduction. When recording information, the magnetic flux generated by the current flowing through the coil 514 leaks from the recording gap 517, which is a gap between the upper recording core 515 and the upper shield 516, so that recording is performed on the magnetic recording medium. Is In reproducing information, a magnetic flux corresponding to the information recorded on the magnetic recording medium acts on the MR element 520 through a reproduction gap 521 which is a gap between the upper shield 516 and the lower shield 522, and the resistance of the MR element 520 is reduced. This is done by changing the value. At this time, magnetic fields other than the magnetic field to be detected by the MR element are limited by the shields 516 and 522, so that a highly sensitive magnetic head can be obtained. Further, by providing the MR element of the present invention, a high-output magnetic head having excellent heat resistance can be obtained. In addition, as a material of the upper shield 516 and the lower shield 522, a soft magnetic material such as Ni-Fe, Fe-Al-Si, or a Co-Nb-Zr alloy can be used.
[0095]
Further, above and below the MR element 520, electrode portions 523 for reading a change in the resistance value of the MR element 520 are arranged. The electrode portion 523 may be connected to the shields 516 and 522 so that the shield also serves as the electrode portion. With this structure, the reproducing head can have a narrower gap.
[0096]
FIG. 18 shows another example of the magnetic head using the MR element according to the present invention. In the example shown in FIG. 18, a yoke 532 for guiding a signal magnetic field to be detected to the MR element 531 is provided. The yoke 532 is generally made of a soft magnetic material. The signal magnetic field from the recording medium is guided to the MR element 531 by the yoke 532, and the yoke 532 also serves as a shield for preventing an external magnetic field from affecting the MR element 531. Play. Note that the yoke 532 may be a part of the magnetic layer of the MR element 531 (part of the free magnetic layer in the case of a spin-valve MR element). In such a yoke type magnetic head, by using the MR element of the present invention, a high-output magnetic head having excellent heat resistance can be obtained.
[0097]
In general, such a yoke type magnetic head is inferior in sensitivity to a shield type magnetic head as shown in FIG. 17, but it is not necessary to arrange an MR element in a shield gap. Is advantageous. In addition, since the MR element 531 is not configured to be exposed to the recording medium, the head is less damaged or worn, and is excellent in reliability.
[0098]
Using the magnetic head according to the present invention, a magnetic recording device such as an HDD can be configured. FIG. 19 shows an example of the magnetic recording apparatus according to the present invention. The magnetic recording device 545 illustrated in FIG. 19 includes a magnetic head 541, a driving unit 542, a magnetic recording medium 543 for recording information, and a signal processing unit 544. By using the magnetic head of the present invention as the magnetic head 541, A stable magnetic recording device having durability against heat can be obtained.
[0099]
Next, FIG. 20 shows an example of an MRAM using the MR element of the present invention as a memory element. The MR elements 601 are arranged in a matrix at the intersections of bit (sense) lines 602 and word lines 603 made of Cu, Al, or the like. The bit line corresponds to a conductor line for information reproduction, and the word line corresponds to a conductor line for information recording. A signal is recorded in the MR element 601 by a composite magnetic field generated when a signal current flows through these lines. The signal is recorded in the element (the MR element 601a in FIG. 13) arranged at the position where the lines in the “on” state intersect (two current matching method).
[0100]
In addition, crosstalk may occur when the switching speed of the signal current flowing through each conductor line is increased to increase the speed of the MRAM or the interval between the conductor lines is decreased to increase the density. . In this case, as shown in FIG. 21, a grounded connection line 604 may be provided between the conductor lines.
[0101]
The operation of the MRAM will be further described with reference to FIGS. These figures show basic examples of a write operation and a read operation. The MR element 701 is the MR element according to the present invention. In the MRAM shown in FIG. 22, a switch element 705 such as an FET is arranged for each element in order to individually read the magnetization state of the MR element 701. This MRAM is suitable for fabrication on a CMOS substrate. In the MRAM shown in FIG. 23, a nonlinear element 706 is arranged for each element. As the nonlinear element 706, a varistor, a tunnel element, the above-described three-terminal element, or the like may be used. A rectifying element can be used instead of the nonlinear element. This MRAM can be manufactured on an inexpensive glass substrate by using a diode film forming process. In the MRAM shown in FIG. 24, the MR element 701 is directly arranged at the intersection of the word line 704 and the bit line 703 without using the switch element or the non-linear element shown in FIGS. In this MRAM, since current flows through a plurality of elements at the time of reading, it is preferable to limit the number of elements to 10000 or less from the reading accuracy.
[0102]
In the examples shown in FIGS. 22 to 24, the bit line 703 is also used as a sense line for reading a resistance change by flowing a current through the element. However, a sense line and a bit line may be separately arranged in order to prevent a malfunction or device destruction due to a bit current. In this case, it is preferable that the bit lines be arranged in parallel with the sense lines while maintaining electrical insulation from the elements. From the viewpoint of power consumption at the time of writing, it is preferable that the distance between the word line and the bit line and the MR element is 500 nm or less.
[0103]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.
[0104]
Using a multi-element magnetron sputtering method, an MR element having the film configuration described in each example was fabricated on a Si substrate with a thermal oxide film (3 inches φ), and the MR characteristics were examined.
[0105]
(Example 1)
[Sample a0 (conventional example)]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Pt-Mn (25) / Co-Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3 ) / Ta (20) [sample a1]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / NiFeCr (X₁) / Pt-Mn (25) / Co-Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample a2]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / NiFeCr (4) / Pt-Mn (25) / Co-Fe (H₁) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample a3]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Pt-Mn (25) / Co-Fe (H₂) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[0106]
Here, the numerical values in parentheses indicate the film thickness. The unit is nm, and hereinafter, the film thickness is similarly indicated. However, the value of the film thickness of the Al-O layer indicates the designed film thickness value (total value) of Al before the oxidation treatment. The Al—O layer was formed by repeatedly oxidizing Al in an oxygen-containing atmosphere after forming an Al film having a thickness of 0.3 to 0.7 nm (the same applies to the following examples unless otherwise specified). X₁, H₁And H₂Indicates that several samples having different film thicknesses for the Ni—Fe—Cr layer and the Co—Fe layer were prepared, and specific numerical values thereof will be described later.
[0107]
Ta (3) / Cu (50) / Ta (3) on the substrate is a lower electrode, and Pt-Mn (25) is a magnetization stable layer composed of an antiferromagnetic layer. NiFeCr (4) adjacent to the Pt-Mn layer is a grain size control layer. Ta (20) farthest from the substrate is a protective layer (also serving as a part of the upper electrode). The compositions of the Pt—Mn layer, the Ni—Fe—Cr layer, the Co—Fe layer, and the Ni—Fe layer are respectively Pt—Mn.₄₉Mn₅₁, Ni₆₀Fe_FifteenCr₂₅, Co₅₀Fe₅₀And Ni₈₀Fe₂₀Met.
[0108]
After film formation of each sample, the substrate was finely processed into a mesa shape as shown in FIG.₂O₃After insulating the surroundings, a through-hole was opened in the upper part, and an upper electrode of Cu (50) / Ta (3) was formed thereon to produce an MR element. The fabricated MR element was subjected to 280 ° C., 5 kOe (4.0 × 10⁵(A / m) in a vacuum magnetic field for 5 hours to impart magnetic anisotropy to the Pt-Mn layer. The element size of each sample was 1.5 μm × 3 μm.
[0109]
For each of the samples prepared as described above, the change in the MR characteristics when the heat treatment was applied (the dependence of the MR characteristics on the heat treatment temperature) was examined. First, each sample was heated to a predetermined heat treatment temperature in a magnetic field-free and hydrogen atmosphere, kept for 30 minutes, cooled to room temperature, and the MR ratio was determined as MR characteristics. For some samples, the MR ratio before the heat treatment was also measured.
[0110]
Samples a0 and a1 were heat-treated at each temperature shown in the graph of FIG. 25, and samples a2 and a3 were heat-treated at 400 ° C.
[0111]
The MR ratio is up to 5 kOe (4.0 × 10⁵(A / m) while measuring the magnetic resistance using a DC four-terminal method while applying a magnetic field. The specific MR ratio is calculated by calculating the maximum resistance value obtained by measuring the magnetoresistance of the element as R_max, And the minimum resistance value is R_minThe following equation (1) was used (the same applies to the following examples).
[0112]
MR ratio = ｛(R_max-R_min) / R_min｝ × 100 (%) (1)
[0113]
The average grain size D of the crystal grains of the Pt—Mn layer, which is the magnetization stable layer of each sample, was measured before the heat treatment. Here, the average particle diameter D is obtained by observing an area of about 10 nm × about 10 nm to about 500 nm × about 500 nm of the magnetization stable layer with a cross-sectional transmission electron microscope, and calculating the average of the grain boundary distance obtained from the obtained microscope image. Value. In addition, an area of about 1 μm × about 1 μm of the magnetization stable layer was subjected to planar observation using an STM (scanning tunnel microscope) and an AFM (atomic force microscope) to confirm the validity of the obtained average particle diameter D. (The same applies to the following examples).
[0114]
The element size W (1.5 μm × 3 μm in this embodiment) is a size confirmed by observation with a scanning electron microscope (SEM). This is calculated from the film rate (the same applies to the following examples).
[0115]
First, a conventional sample a0 and a sample a1 (X₁= 4) is shown in FIG. 25 at each heat treatment temperature. As shown in FIG. 25, it can be seen that the sample a1 has an improved MR ratio at the same heat treatment temperature as compared to the sample a0. Sample a1 is an example in which a particle size control layer is provided, and shows that it is more effective in improving heat resistance than the conventional example. Note that, for each of the samples a0 and a1, 15 samples each having the same film configuration were prepared and the same measurement was performed, but all the results were the same.
[0116]
When the average particle diameter D of the magnetization stable layers (Pt-Mn (25)) of both samples was measured, the average particle diameter D of the sample a0 was about 0.5 to 2.5 nm, whereas the average particle diameter D of the sample a1 was about 0.5 to 2.5 nm. Mean particle size D was greatly increased to about 10 to 25 nm. FIG. 26 shows an AFM image of the surface of the magnetization stable layer in each sample. It can be seen that, in the sample a1 shown in FIG. 26B, the crystal grains of the magnetization stable layer grow in comparison with the sample a0 shown in FIG. Considering the results of the dependence of the MR ratio on the heat treatment temperature in both samples, in sample a1, the provision of the grain size control layer increases the grain size of the Pt—Mn layer, which is the magnetization stable layer, and reduces the heat resistance of the device. May have improved significantly.
[0117]
Next, for sample a1, the film thickness X of the Ni—Fe—Cr layer,₁6 kinds of samples were prepared by changing (X₁= 1, 2, 3, 4, 5, and 10 nm), and the average grain size D of the magnetization stable layer and the MR ratio after heat treatment (400 ° C.) were measured as MR characteristics of the device. The measurement results are shown in Table 1 together with the sample a0 as a comparative example. In samples a0 and a1, the distance H between the magnetization stable layer and the nonmagnetic layer is 3 nm. In addition, each of the six types of samples was measured with a sample number n = 15 having the same configuration. The MR ratio is represented by the average value of all the values obtained at n = 15. The average particle diameter D is obtained by first calculating the average value of the intergranular distance in n = 1 measurement. Are shown in the range of the average value obtained in the above.
[0118]
[Table 1]

[0119]
As shown in Table 1, the film thickness X of the Ni—Fe—Cr layer₁It can be seen that the average grain size D of the magnetization stable layer adjacent to the Ni—Fe—Cr layer increases as the value increases, and the MR ratio after the heat treatment improves. At this time, it can be seen that the entire range of the average particle diameter D satisfies the relationship of D ≧ 2 × H, and the improvement of the MR ratio is obtained.
[0120]
Regarding the average particle diameter D and the MR ratio after heat treatment shown in Table 1, the film thickness X of the Ni—Fe—Cr layer₁FIG. 27 shows a graph in which is used as the horizontal axis. In FIG. 27, the bar indicating the value of the average particle diameter D reflects the range of the obtained average particle diameter D (the same applies to FIGS. 28 and 29 hereinafter).
[0121]
According to FIG. 27, by providing the grain size control layer, the MR ratio of the device after the heat treatment can be improved (in the conventional example without the grain size control layer, the MR ratio after the heat treatment = 0%). But the film thickness X₁It can be seen that especially when the average particle diameter D is 10 nm or more, the MR ratio is particularly improved.
[0122]
Subsequently, as sample a2, six types of samples in which the distance H between the magnetization stable layer and the nonmagnetic layer was changed were prepared (H = H₁= 2, 3, 4, 5, 6, and 8 nm), and the average grain size D of the magnetization stable layer and the MR ratio after heat treatment (400 ° C.) were measured as MR characteristics of the device. Table 2 shows the measurement results. As in the case of the sample a1, the measurement was performed at n = 15, the MR ratio was represented by the average value of all the values obtained at n = 15, and the average particle size D was the particle size at n = 1 measurement. The average value of the inter-field distance is first determined, and is shown in the range of the average value obtained for each of n = 15.
[0123]
[Table 2]

[0124]
By providing the grain size control layer (Ni-Fe-Cr (4)), the average grain size D was all 10 nm or more, and the MR ratio was greatly improved as compared with the conventional example. Further, the MR ratio obtained by increasing the distance H was further improved. When the distance H was 5 nm or more, an MR ratio of about 40% could be obtained. It can be seen that by controlling the average particle diameter D and the distance H, an MR element having more excellent heat resistance can be obtained. FIG. 28 is a graph showing the average particle diameter D and the MR ratio after the heat treatment shown in Table 2 using the distance H on the horizontal axis.
[0125]
Next, as the sample a3, six types of samples in which the distance H between the magnetization stable layer and the nonmagnetic layer was changed were prepared (H = H₂= 2, 3, 4, 5, 8, and 10 nm), and the average grain size D of the magnetization stable layer and the MR ratio after heat treatment (400 ° C.) were measured as the MR characteristics of the device. Table 3 shows the measurement results. As in the case of the sample a1, the measurement was performed at n = 15, the MR ratio was represented by the average value of all the values obtained at n = 15, and the average particle size D was the particle size at n = 1 measurement. The average value of the inter-field distance is first determined, and is shown in the range of the average value obtained for each of n = 15.
[0126]
[Table 3]

[0127]
As shown in Table 3, since the film configuration of the device did not include the grain size control layer, the value of the average grain size D of the magnetization stable layer was as small as 0.5 to 2.5 nm, which was similar to the conventional example. However, when the distance H was 4 nm or more (that is, the distance H satisfied the relationship of H ≧ 1.4 × D), the MR ratio after the heat treatment could be improved. FIG. 29 is a graph showing the average particle diameter D and the MR ratio after the heat treatment shown in Table 3 using the distance H on the horizontal axis.
[0128]
Here, for each of the samples a1 and a3 (including a total of twelve samples of six types) including the sample having an average particle diameter D after the heat treatment at 400 ° C. of 1 nm ≦ D <10 nm, 1 FIG. 30 is a graph in which 0.4 × D / H is plotted on the horizontal axis and 2 × H / D is plotted on the vertical axis. In the graph of FIG. 30, the distribution in the plot of each sample corresponds to the distribution in the value of the average particle diameter D obtained by the measurement of each sample. In the legend of the graph, “a1” and “a3” represent “sample a1” and “sample a3”, respectively, and “X1” represents the film thickness X of the Ni—Fe—Cr layer in sample a1.₁"H" means "distance H between the magnetization stable layer and the nonmagnetic layer" in sample a3.
[0129]
Comparing FIG. 30 with the results of Tables 1 and 3, when the relationship of 1.4 × D / H ≦ 1 or 2 × H / D ≦ 1 is satisfied (that is, H ≧ 1.4 × D or D ≧ 2 × H), the heat resistance of the MR element is improved. At this time, it can be said that it is preferable that all the distributions of the plots of the respective samples (that is, the entire range of the obtained average particle diameter D) satisfy the above relationship.
[0130]
As shown in Tables 1 to 3, when the average particle diameter D of the magnetization stable layer is 10 nm or more, or when the average particle diameter D and the distance H are D ≧ 2 × H or H ≧ 1.4. When the relationship of × D is satisfied, an MR element having excellent heat resistance can be obtained. In particular, when the average particle diameter D is 10 nm or more, an MR element with particularly improved MR characteristics can be obtained.
[0131]
Thus, the change in the MR characteristics before and after the high-temperature heat treatment may depend on the crystal grain size of the magnetization stable layer such as the antiferromagnetic layer and the distance between the magnetization stable layer and the nonmagnetic layer. In this embodiment, as the crystal grain size of the antiferromagnetic layer, which is the magnetization stable layer, is larger, or the distance between the antiferromagnetic layer and the nonmagnetic layer, which is considered to greatly contribute to the MR characteristics, is larger. It was shown that the further the distance, the more the deterioration of MR characteristics at high temperature was suppressed. It is conceivable that the element having the above-described configuration suppresses diffusion of Mn, which is a diffusion element species in the antiferromagnetic layer, into the nonmagnetic layer.
[0132]
Further, the composition uneven distribution of the Pt—Mn layer in each sample of the present example was evaluated using ICP and EPMA (electron beam microanalysis). In the Pt-Mn layer of the sample a0 which is the conventional example, it was confirmed that a region having an Mn content of 60 at% or more was localized around the periphery of the crystal grain boundary. -It turned out that it occupies about 25 vol% of the Mn layer.
[0133]
Such a compositional uneven distribution may occur when a compositional deviation occurs during film formation by a sputtering method, and the deviation segregates around a crystal grain boundary. In particular, when the conditions for manufacturing the thin film of the Pt-Mn layer are inappropriate, the above compositional deviation is remarkable, and the Mt uneven distribution is stronger as the composition of the Pt-Mn layer deviates from the optimum composition as the magnetization stable layer. Thus, the MR characteristics after the heat treatment tend to deteriorate. Although it is not clear, such a compositional uneven distribution may be the cause of the deterioration of the MR characteristics due to the high-temperature heat treatment in the conventional sample a0.
[0134]
On the other hand, in the sample a1 and the sample a2, it was confirmed that the region having the Mn content of 60 at% or more was unevenly distributed around the periphery of the crystal grain boundary. It was 25 vol% or less. The existence of the grain size control layer may increase the crystal grain size of the Pt-Mn layer, which may be due to the fact that the grain boundaries present in the Pt-Mn layer are reduced.
[0135]
From the above results, the magnetization stable layer is represented by the formula Mn-Z (where Z is at least one element selected from Pt, Pd, Fe, Ir, Ni, Co, Rh, O, C, F, N and B) In the case of an antiferromagnetic layer made of an alloy having a composition represented by the following formula (Z is Pt in this embodiment), the composition unevenly distributed region having a Mn content of 60 at% or more is 25 vol% or less of the entire magnetization stable layer. Is preferable. Under such conditions, the deterioration of the MR characteristics in the high-temperature heat treatment is further suppressed, and a higher MR ratio can be secured after the heat treatment. This condition can be realized by disposing a particle size control layer.
[0136]
In this example, a Ni—Fe—Cr layer was used as the grain size control layer. However, similar results can be obtained by using Pt, Ta, Nb, Hf, Zr, Cr, Ni—Fe, or the like. I was able to. When Pt is used as the grain size control layer, if the Pt layer is formed under a heating condition of about 100 to 400 ° C., the crystallinity of the Pt layer is improved, and the average grain size of the magnetization stable layer can be further increased. It was possible.
[0137]
(Example 2)
[Sample b0 (conventional example)]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Pt-Mn (25) / Co-Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3 ) / Ta (20) [sample b1]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Pt-Mn (25) / Co-Fe (H₃) / Ru (0.7) / Co-Fe (H₃) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample b2]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / NiFeCr (4) / Pt-Mn (25) / Co-Fe (H₄) / Ru (0.7) / Co-Fe (H₄) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample b3]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / NiFeCr (4) / Pt-Mn (25) / Co-Fe (3) / Ru (0.7) / Co-Fe (3) / Al- O (0.7) / Co-Fe (1) / Ni-Fe (3) / Ru (0.7) / Ni-Fe (2) / Ta (20)
[0138]
Ta (3) / Cu (50) / Ta (3) on the substrate is a lower electrode, and Pt-Mn (25) is a magnetization stable layer composed of an antiferromagnetic layer. NiFeCr (4) adjacent to the Pt-Mn layer is a grain size control layer. Ta (20) farthest from the substrate is a protective layer (also serving as a part of the upper electrode). H₃And H₄Indicates that several samples having different thicknesses were prepared for the Co—Fe layer.₃, H₄In each case, 4, 3, 4, and 5 nm were prepared. The compositions of the Pt—Mn layer, the Ni—Fe—Cr layer, the Co—Fe layer, and the Ni—Fe layer are respectively Pt—Mn.₄₉Mn₅₁, Ni₆₀Fe_FifteenCr₂₅, Co₅₀Fe₅₀And Ni₈₀Fe₂₀Met.
[0139]
After forming a film and forming an upper electrode on each sample in the same manner as in Example 1, 280 ° C., 5 kOe (4.0 × 10 4⁵(A / m) for 5 hours to give the Pt-Mn layer magnetic field anisotropy. The device size of each sample was 1.5 μm × 3 μm.
[0140]
For each of the samples prepared as described above, the average grain size D of the magnetization stable layer was measured, and then the change in MR characteristics when heat treatment was applied (the dependence of the MR characteristics on the heat treatment temperature) was examined. First, each sample was heated to a heat treatment temperature (400 ° C.) in a magnetic field-free and hydrogen atmosphere, kept for 30 minutes, cooled to room temperature, and the MR ratio was determined as MR characteristics.
[0141]
The MR ratio of the sample b0, which is a conventional example, before the heat treatment was about 40%, but the MR characteristics were significantly deteriorated by the heat treatment, and the MR ratio after the heat treatment became 0%. For sample b0, fifteen samples having the same film configuration were prepared and the same measurement was performed, but all the results were the same. In addition, the range of the average particle diameter D of the magnetization stable layer in the sample b0 was 0.5 to 2.5 nm.
[0142]
Next, Table 4 shows the measurement results of the sample b1 in which the distance H between the antiferromagnetic layer, which is the magnetization stable layer, and the nonmagnetic layer was increased by introducing the laminated ferrimagnetic pinned layer. As in the other samples, the measurement was performed at n = 15, the MR ratio was represented by the average value of all the values obtained at n = 15, and the average particle diameter D was determined by n = 1 measurement. The average value of the intergranular distances is first determined, and is shown in the range of the average values obtained for each of n = 15.
[0143]
[Table 4]

[0144]
As shown in Table 4, the MR ratio of sample b1 did not become 0% even after the heat treatment at 400 ° C., indicating that the heat resistance of the element was improved as compared with the conventional example. Further, as the distance H increased, a larger MR ratio could be obtained.
[0145]
Next, Table 5 shows the measurement results of Sample b2 having a film configuration in which a particle size control layer was further disposed on Sample b1. As in the other samples, the measurement was performed at n = 15, the MR ratio was represented by the average value of all the values obtained at n = 15, and the average particle diameter D was determined by n = 1 measurement. The average value of the intergranular distances is first determined, and is shown in the range of the average values obtained for each of n = 15.
[0146]
[Table 5]

[0147]
The sample b2 having the particle size control layer was a high-output MR element having more excellent heat resistance than the sample b1. It is considered that the provision of the grain size control layer has a great effect that the average grain size D of the magnetization stable layer becomes 10 nm or more.
[0148]
In addition, when the minor curves in the magnetoresistance measurement for obtaining the MR ratio were compared for the samples b1 and b2, the results shown in FIG. 31 were obtained. FIG. 31A shows the minor curve of the sample b2, and FIG. 31B shows the minor curve of the sample b1.
[0149]
As shown in FIG. 31 (b), in sample b1, the MR ratio after the heat treatment was improved, and although there was no problem in use as an MR element, spin valve characteristics were disturbed. On the other hand, in the sample b2, not only the MR ratio was further improved, but also no disturbance occurred in the spin valve characteristics. It is conceivable that the provision of the grain size control layer may be due to the effect that the average grain size D of the magnetization stable layer is 10 nm or more.
[0150]
Next, in sample b3 in which a laminated ferrimagnetic free layer was further introduced into sample b2, an MR ratio almost the same as that of sample b2 was obtained even after the heat treatment at 400 ° C., and there was no disturbance in the spin valve characteristics. Further, by providing the laminated ferrimagnetic free layer, it was possible to simultaneously reduce the magnetization reversal magnetic field of the free magnetic layer.
[0151]
Also in this embodiment, as in the first embodiment, the larger the crystal grain size of the antiferromagnetic layer, which is the magnetization stable layer, or the more the antiferromagnetic layer and the nonmagnetic layer which are considered to greatly contribute to MR characteristics. It was shown that the longer the distance was, the more the deterioration of MR characteristics at high temperature was suppressed. It is conceivable that the element having the above-described configuration suppresses diffusion of Mn, which is a diffusion element species in the antiferromagnetic layer, into the nonmagnetic layer.
[0152]
(Example 3)
In this embodiment, an example in which a diffusion control layer is further provided will be described.
[0153]
[Sample c0-A (Comparative Example)]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Ir-Mn (25) / Co-Fe (3) / Ru (0.7) / Co-Fe (3) / Al-O (0.7 ) / Co—Fe (2) / Ni—Fe (3) / Ta (20)
[Sample c0-B (Comparative Example)]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Ni-Fe (3) / Co-Fe (2) / Al-O (0.7) / Co-Fe (3) / Ru (0.7 ) / Co—Fe (3) / Ir—Mn (20) / Ta (20)
[Sample c1]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Ir-Mn (25) / MX (2) / Co-Fe (1) / Ru (0.7) / Co-Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample c2]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Ni-Fe (3) / Co-Fe (2) / Al-O (0.7) / Co-Fe (3) / Ru (0.7 ) / Co—Fe (1) / MX (2) / Ir—Mn (20) / Ta (20)
[Sample c3]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / NiFeCr (4) / Ir-Mn (25) / MX (2) / Co-Fe (1) / Ru (0.7) / Co- Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample c4]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / NiFeCr (4) / Ir-Mn (25) / MX (2) / Co-Fe (2) / Ru (0.7) / Co- Fe (4) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample c5]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / MX (2) / Ir-Mn (25) / Co-Fe (3) / Ru (0.7) / Co-Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[Sample c6]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / MX (2) / Ir-Mn (25) / MX (2) / Co-Fe (1) / Ru (0.7) / Co-Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[0154]
Ta (3) / Cu (50) / Ta (3) on the substrate is a lower electrode, and Ir-Mn (25) and Ir-Mn (20) are magnetization stable layers composed of an antiferromagnetic layer. NiFeCr (4) adjacent to the Ir-Mn layer is a grain size control layer. Ta (20) farthest from the substrate is a protective layer (also serving as a part of the upper electrode). The compositions of the Ir—Mn layer, the Ni—Fe—Cr layer, the Co—Fe layer, and the Ni—Fe layer are respectively Ir₂₀Mn₈₀, Ni₆₀Fe_FifteenCr₂₅, Co₅₀Fe₅₀And Ni₈₀Fe₂₀Met.
[0155]
The MX layer of each sample is a diffusion control layer made of a ferromagnetic material MX.
[0156]
After forming a film and forming an upper electrode on each sample in the same manner as in Example 1, 280 ° C., 5 kOe (4.0 × 10 4⁵(A / m) for 5 hours to impart magnetic field anisotropy to the Ir-Mn layer. The device size of each sample was 1.5 μm × 3 μm.
[0157]
For each of the samples prepared as described above, the average particle diameter D of the magnetization stable layer was determined, and then a change in the MR characteristics when the heat treatment was applied (the dependence of the MR characteristics on the heat treatment temperature) was examined. First, each sample was heated to a heat treatment temperature (400 ° C.) in a magnetic field-free and hydrogen atmosphere, kept for 30 minutes, then cooled to room temperature, and the MR ratio was determined as MR characteristics.
[0158]
Table 6 shows the measurement results of the samples c0A, c0B, and c1 to c4. As in Examples 1 and 2, the measurement was performed at n = 15, the MR ratio was shown in the average value, and the average particle size D was shown in the range of the obtained values.
[0159]
[Table 6]

[0160]
Sample c0A, which is a comparative example, is a sample having the same film configuration as sample b1 in Example 2 except that an Ir—Mn layer is used as the magnetization stable layer. Sample c0A had an MR ratio of 35% before the heat treatment, but the MR ratio obtained after the heat treatment was 4%. Sample c0B, which is also a comparative example, is an element in which an Ir—Mn layer, which is a magnetization stabilizing layer, is disposed above the element (on the side opposite to the substrate with the nonmagnetic layer interposed). The MR ratio obtained after the heat treatment was 2%. The average particle diameter D of the magnetization stable layer was 0.5 to 2.5 nm for both the samples c0A and c0B. However, in both samples, the distance H between the magnetization stable layer and the non-magnetic layer was set to a value satisfying the relationship of H ≧ 1.4 × D. Therefore, unlike the conventional examples such as the sample a0 and the sample b0, at 400 ° C. The MR output could be obtained even after the heat treatment. However, the spin valve characteristics of both samples c0A and c0B were disturbed.
[0161]
Sample c1 is a sample having a film configuration in which a diffusion control layer made of a ferromagnetic material MX is introduced into sample c0A.
[0162]
For example, when Fe—Pt (Pt composition is 5 to 10 at%) is used as the ferromagnetic material MX, the MR ratio after heat treatment at 400 ° C. exceeds 35%, which is higher than that of sample c0A as a comparative example. The element further improved in heat resistance. However, as shown in FIG. 32, although there is no problem in use as an MR element, the spin valve characteristics are disturbed. FIG. 32A shows the minor curve before the heat treatment, and FIG. 32B shows the minor curve after the heat treatment.
[0163]
Sample c2 is a sample having a film configuration in which a diffusion control layer made of a ferromagnetic material MX is introduced into sample c0B. Similarly, when Fe—Pt (Pt composition is 5 to 10 at%) is used as the ferromagnetic material MX, the MR ratio after heat treatment at 400 ° C. is 27%, which is lower than that of the comparative example (sample c0B). The result was a significant improvement. However, also in sample c2, as in sample c1, the result was that the spin valve characteristics were disturbed.
[0164]
In sample c3 (ferromagnetic material MX is the same as sample c1) in which a particle size control layer is further added to sample c1, the average particle size D is 10 nm or more, and the MR ratio after heat treatment at 400 ° C. is the same as sample c1. As a result, it was possible to obtain an MR element having a higher heat resistance and more excellent heat resistance. Also, the spin valve characteristics could be maintained without being disturbed.
[0165]
In the sample c4 (the ferromagnetic material MX is the same as the sample c3) in which the distance H of the sample c3 is further increased, the MR ratio is further improved.
[0166]
Further, as in a sample c5 (the ferromagnetic material MX is the same as the samples c1 to c4), a diffusion control layer made of a ferromagnetic material MX is provided between the substrate and the Ir-Mn layer which is a magnetization stable layer. In the sample in which is disposed, an MR ratio of 10% or more can be obtained after the heat treatment at 400 ° C., and an MR element having more excellent heat resistance than the conventional examples such as the sample a0 and the sample b0 can be obtained. Like the sample c6 (the ferromagnetic material MX is the same as the samples c1 to c5), the sample in which the diffusion control layer made of the ferromagnetic material MX is disposed on both surfaces of the magnetization stabilizing layer also after the heat treatment at 400 ° C. The MR element exhibited an MR ratio of 35% or more and was excellent in heat resistance.
[0167]
From the above results, an MR element having more excellent heat resistance can be obtained by controlling the average grain size D and the distance H of the magnetization stable layer and further arranging the diffusion control layer and / or the grain size control layer. I understand.
[0168]
In the present embodiment, an example in which Fe-Pt (the composition of Pt is 5 to 10 at%) is used as the ferromagnetic material MX has been described. However, at least M is at least one selected from Fe, Co, and Ni. When one kind of magnetic element is X, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, Al, Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Hf, Even when at least one non-magnetic element selected from Ta, W, Re, Ga, Ge, lanthanoid, Si, B, C, N, O, P and S is used, an MR element having excellent heat resistance is obtained. I was able to.
[0169]
Table 7 to Table 11 show the MR ratios of the sample c03 obtained by changing the composition of the ferromagnetic material MX and performing the same heat treatment at 400 ° C. as the other samples.
[0170]
[Table 7]

[0171]
[Table 8]

[0172]
[Table 9]

[0173]
[Table 10]

[0174]
[Table 11]

[0175]
As shown in Tables 7 to 11, it can be seen that by arranging the diffusion control layer made of the ferromagnetic material MX described above, an MR element having more excellent heat resistance can be obtained.
[0176]
(Example 4)
[Sample d0 (conventional example)]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Pt-Mn (20) / Co-Fe (3) / Ru (0.8) / Co-Fe (3) / Al-O (1.0 ) / Ni-Fe (3) / Al-O (1.0) / Co-Fe (3) / Ru (0.8) / Co-Fe (3) / Pt-Mn (20) / Ta (15)
[Sample d1]
Si substrate with thermal oxide film / Ta (3) / Cu (50) / Ta (3) / NiFeCr (5) / Pt-Mn (20) / Fe-Pt (2) / Co-Fe (1) / Ru ( 0.8) / Co-Fe (1) / Fe-Pt (2) / Al-O (1.0) / Ni-Fe (3) / Al-O (1.0) / Fe-Pt (2) /Co-Fe(1)/Ru(0.8)/Co-Fe(1)/Fe-Pt(2)/Pt-Mn(15)/Ta(15)
[0177]
Ta (3) / Cu (50) / Ta (3) on the substrate is a lower electrode, and Pt-Mn (20) and Pt-Mn (15) are magnetization stable layers composed of an antiferromagnetic layer. NiFeCr (5) adjacent to the Pt-Mn layer is a grain size control layer. Ta (15) farthest from the substrate is a protective layer (also serving as part of the upper electrode), and the Fe-Pt layer is a diffusion control layer made of a ferromagnetic material MX. The compositions of the Pt—Mn layer, Ni—Fe—Cr layer, Co—Fe layer, Ni—Fe layer, and Fe—Pt layer are each Pt—Mn.₄₉Mn₅₁, Ni₆₀Fe_FifteenCr₂₅, Co₅₀Fe₅₀, Ni₈₀Fe₂₀, Fe_0.85Pt_0.15Met.
[0178]
After forming a film and forming an upper electrode on each sample in the same manner as in Example 1, 280 ° C., 5 kOe (4.0 × 10 4⁵(A / m) for 5 hours to give the Pt-Mn layer magnetic field anisotropy. The device size of each sample was 0.5 μm × 1 μm.
[0179]
For each of the samples prepared as described above, the average particle diameter D of the magnetization stable layer was determined, and then a change in the MR characteristics when the heat treatment was applied (the dependence of the MR characteristics on the heat treatment temperature) was examined. First, each sample was heated to a heat treatment temperature (400 ° C.) in a magnetic field-free and hydrogen atmosphere, kept for 30 minutes, then cooled to room temperature, and the MR ratio was determined as MR characteristics.
[0180]
Sample d0, which is a conventional example, showed an MR ratio of about 35% or more before the heat treatment, but the heat treatment significantly deteriorated the MR characteristics, and the obtained MR ratio became 0%. The same measurement was performed by preparing 15 samples having the same film configuration, but all the results were the same. Note that the average particle size D of the magnetization stable layer in the sample d0 was 0.5 to 2.5 nm.
[0181]
Sample d1 is an example in which a diffusion control layer and a grain size control layer are added to sample d0, which is a conventional example, but the MR ratio obtained after heat treatment exceeds 50%, which is significantly larger than the conventional example. An improvement in heat resistance was observed. The average particle size D of the magnetization stable layer was 10 nm to 25 nm, and the spin valve characteristics could be maintained without being disturbed.
[0182]
Next, the bias voltage dependence of the samples d0 and d1 before and after the heat treatment was determined. Generally, in an MR element, the MR ratio of the element decreases with the application of a bias voltage. The bias voltage V when the MR ratio is halved with reference to the MR ratio of the element in a state where no bias voltage is applied (strictly speaking, the bias voltage is close to 0)_hBefore and after the heat treatment.
Table 12 shows the measurement results.
[0183]
(Table 12)
――――――――――――――――――――――――――――
Sample No. ＶBefore heat treatment V_h(MV) V after heat treatment_h(MV)
――――――――――――――――――――――――――――
Sample d0 950 690
Sample d1 1500 1640
――――――――――――――――――――――――――――
[0184]
As shown in Table 12, in sample d0, which is a conventional example, V_hIs declining. On the other hand, in sample d1, V_hDid not decrease, but rather increased. From this result, it can be seen that the sample d1 is a device having more excellent heat resistance than the conventional example.
[0185]
(Example 5)
[Sample e0 (conventional example)]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / Pt-Mn (25) / Co-Fe (3) / Ru (0.7) / Co-Fe (3) / Al-O (0.7 ) / Co—Fe (2) / Ni—Fe (3) / Ta (20)
[Sample e1]
Si substrate with thermal oxide film /
Ta (3) / Cu (50) / Ta (3) / NiFeCr (4) / Pt-Mn (25) / Co-Fe-B (1) / Co-Fe (2) / Ru (0.7) / Co-Fe (3) / Al-O (0.7) / Co-Fe (2) / Ni-Fe (3) / Ta (20)
[0186]
Ta (3) / Cu (50) / Ta (3) on the substrate is a lower electrode, and Pt-Mn (25) is a magnetization stable layer composed of an antiferromagnetic layer. NiFeCr (4) adjacent to the Pt-Mn layer is a grain size control layer. Ta (20) farthest from the substrate is a protective layer (also serving as a part of the upper electrode). The compositions of the Pt—Mn layer, the Ni—Fe—Cr layer, the Co—Fe layer, and the Ni—Fe layer are respectively Pt—Mn.₄₉Mn₅₁, Ni₆₀Fe_FifteenCr₂₅, Co₅₀Fe₅₀, Ni₈₀Fe₂₀Met.
[0187]
After forming a film and forming an upper electrode on each sample in the same manner as in Example 1, 280 ° C., 5 kOe (4.0 × 10 4⁵(A / m) for 5 hours to give the Pt-Mn layer magnetic field anisotropy. The device size of each sample was 0.5 μm × 1 μm.
[0188]
Co-Fe-B (1) in contact with Pt-Mn (25) in sample e1 is an example of a magnetic layer containing a large amount of microcrystalline or amorphous material.
[0189]
For each of the samples prepared as described above, the average grain size D of the magnetization stable layer was measured, and then the change in MR characteristics when heat treatment was applied (the dependence of the MR characteristics on the heat treatment temperature) was examined. First, each sample was heated to a heat treatment temperature (400 ° C.) in a magnetic field-free and hydrogen atmosphere, kept for 30 minutes, then cooled to room temperature, and the MR ratio was determined as MR characteristics.
[0190]
In sample e0, which is a conventional example, the MR ratio before the heat treatment was 45% or more, but the heat treatment at 400 ° C. greatly deteriorated the MR characteristics of the element, and the MR ratio obtained after the heat treatment was 0%. For sample e0, fifteen samples having the same film configuration were prepared and the same measurement was performed, but all the results were the same. The average particle size D of the magnetization stable layer of the sample d0 was 0.5 to 2.5 nm.
[0191]
On the other hand, in sample e1, the MR characteristics of the element were not significantly degraded by the heat treatment, and an MR ratio of 20% or more could be obtained even after the heat treatment at 400 ° C.
[0192]
As in the sample e1, at least one layer having a main structure of microcrystal or amorphous, such as a Co—Fe—B layer, is disposed between the magnetization stable layer and the nonmagnetic layer, so that the magnetization stable layer is formed. Is considered to be effective in preventing the diffusion of the diffusion element species contained in. This suggests that the diffusion element has a diffusion path around the grain boundary of each layer to some extent, and there is an effect that the diffusion path is separated by the layer having a main structure of microcrystal or amorphous. It is presumed that it is. Here, the main structure means a structure occupying about 50 vol% or more of the layer, and the microcrystal means a state in which crystals having a diameter of at least 1 μm or less are dispersed without being oriented in one direction. Means.
[0193]
In this embodiment, an example using a Co—Fe—B layer is shown. However, similarly to the case of Co—Fe—B, Ni—Fe—B that is stable as microcrystal or amorphous is used. Results were obtained.
[0194]
(Example 6)
Using the sample a0 manufactured in Example 1 and the sample c3 manufactured in Example 3, a magnetic head having a shield as shown in FIG. 17 was manufactured, and its characteristics were evaluated. However, in this embodiment, Pt—Mn (25) (composition: Pt—Mn) is used instead of the antiferromagnetic layer Ir—Mn (25), which is the magnetization stable layer of sample c3.₄₉Mn₅₁) And an Fe—Pt layer (composition Fe₈₅Pt_Fifteen) Was used.
[0195]
Al as substrate for magnetic head₂O₃Using a TiC substrate, the composition is Ni as the upper recording core, upper shield and lower shield.₈₀Fe₂₀Was used. Further, a laminated film of Au is used as an electrode for holding the MR element, and an Al film is used as an insulating film.₂O₃Was used.
[0196]
In the MR element, the magnetic layer (Co—Fe (2) / Ni—Fe (3)) corresponding to the free magnetic layer corresponds to the fixed magnetic layer such that the direction of easy magnetization is perpendicular to the signal magnetic field direction to be detected. The magnetization direction of the magnetic layer (Pt-Mn (25) / Fe-Pt (2) / Co-Fe (1) / Ru (0.7) / Co-Fe (3)) is parallel to the signal magnetic field direction to be detected. Anisotropy was given so that This anisotropy is imparted by first preparing an MR element at 300 ° C., 5 kOe (4.0 × 10⁵A / m) in a magnetic field to define the magnetization direction of the pinned magnetic layer, and then at 200 ° C., 10 kOe (8.0 × 10⁵(A / m) in a magnetic field to define the direction of easy magnetization of the free magnetic layer.
[0197]
The track width of the MR element in the reproducing section was 0.1 μm, and the MR height was 0.1 μm.
[0198]
Heat treatment (400 ° C., in vacuum, 30 minutes) was applied to the magnetic head manufactured as described above to evaluate characteristics. A DC current of 1 A is passed as a sense current, and 50 Oe (4.0 × 10³When the output of the head was evaluated by applying an AC signal magnetic field of (A / m), no output was obtained with the magnetic head using the conventional sample a0 as the MR element, whereas the sample c3 was used. With the magnetic head, an output of 15 mV / μm or more could be obtained.
[0199]
When a magnetic recording apparatus (HDD) as shown in FIG. 19 was manufactured using the above-described magnetic head including the sample c3 as the MR element, 100 Gbit / in²The above areal recording density was achieved. Further, when an environmental test (test time: 30 minutes) was performed on the manufactured magnetic recording device at an external temperature of 150 ° C. and a corresponding internal temperature of 400 ° C., the above output was maintained, and the magnetic recording device was excellent in heat resistance. Could be obtained.
[0200]
(Example 7)
Using the sample c3 manufactured in Example 3, a magnetic head having a yoke as shown in FIG. 18 was manufactured, and its characteristics were evaluated. However, in this embodiment, Pt—Mn (25) (composition: Pt—Mn) is used instead of the antiferromagnetic layer Ir—Mn (25), which is the magnetization stable layer of sample c3.₄₉Mn₅₁) And an Fe—Pt layer (composition Fe₈₅Pt_Fifteen) Was used.
[0201]
The yoke has a composition of Ni₈₀Fe₂₀Was used. The magnetic head was manufactured by polishing the Ni—Fe surface serving as the yoke by CMP, forming an MR element, and finally stacking an electrode film made of Au. The element size of the MR element in the reproducing head was 0.3 μm × 0.3 μm.
[0202]
As in the sixth embodiment, the MR element has a signal whose magnetization direction of the magnetic layer corresponding to the fixed magnetic layer is to be detected such that the easy magnetization direction of the magnetic layer corresponding to the free magnetic layer is perpendicular to the signal magnetic field direction to be detected. Anisotropy was provided so as to be parallel to the direction of the magnetic field.
[0203]
A heat treatment (400 ° C., in vacuum, 30 minutes) was applied to the head manufactured as described above to evaluate the characteristics. A DC current of 1 A is passed as a sense current, and 50 Oe (4.0 × 10³When the output of the head was evaluated by applying an AC signal magnetic field of (A / m), an output of 10 mV / μm or more could be obtained.
[0204]
(Example 8)
An MRAM as shown in FIG. 20 was manufactured by using the MR elements manufactured in Example 3 (conventional example c0A and example c3). However, an Fe—Pt layer (composition Fe₈₅Pt_Fifteen) Was used.
[0205]
The fabrication of the MRAM was performed as follows. First, a word line made of Cu is formed on a Si substrate having a 300 nm thermal oxide film, and an Al₂O₃After forming the insulating film, a lower electrode made of Cu was formed. Here, after the lower electrode surface was once smoothed by CMP, the MR elements having the film configurations shown in Sample c0A and Sample c3 were stacked.
[0206]
Next, at 280 ° C., 5 kOe (4.0 × 10 4) so that an exchange coupling magnetic field is generated between the Ir—Mn layer as the antiferromagnetic layer and the fixed magnetic layer.⁵(A / m) in a magnetic field for 5 hours. Thereafter, as in the first embodiment, a mesa-type processing or the like was performed to form an MR element. Finally, a bit line was formed as an upper electrode, and a single magnetic memory having no switch element as shown in FIG. 24 was manufactured.
[0207]
With respect to the manufactured magnetic memory, a current is applied to the word line and the bit line to generate a magnetic field, and the magnetization of the free magnetic layer (Co—Fe (2) / Ni—Fe (3) in the present embodiment) of the MR element. The information "0" was recorded by reversing the direction. Next, a current was applied to the word line and the bit line in a direction opposite to the previous direction to generate a magnetic field, and the magnetization of the free magnetic layer was inverted to record information “1”. After that, a sense current was applied by applying a bias voltage to the MR element in each state, and the difference between the element voltages in the state of information "0" and the state of information "1" was measured. And the same level of output difference was obtained. Therefore, it was found that both the embodiment and the conventional example were magnetic memories in which the free magnetic layer was an information recording layer.
[0208]
Next, the above-mentioned MR element was arranged on a CMOS substrate to produce an integrated magnetic memory as shown in FIG. The element arrangement was a total of eight blocks, with a memory of 16 × 16 elements as one block. The arrangement of the MR elements was performed as follows. First, FETs as switching elements were arranged in a matrix on a CMOS substrate, and the surfaces were flattened by CMP. Then, the MR elements of Example c3 and the conventional example c0A were arranged in a matrix corresponding to the FETs. Each element size was 0.2 μm × 0.3 μm. One element in each block was a dummy element for canceling wiring resistance, element minimum resistance, FET resistance, and the like. Note that Cu was used for all the word lines, bit lines, and the like. After forming the magnetic memory, hydrogen sintering was performed at 400 ° C.
[0209]
With respect to the magnetic memory thus manufactured, the magnetization reversal of the free magnetic layer of each of the eight elements in each block was simultaneously performed by the combined magnetic field of the word lines and the bit lines, and signals were recorded. Next, the gate of the FET was turned on one element at a time in each block, and a sense current was passed through the element. At this time, the voltage generated in the bit line, element and FET in each block was compared with the dummy voltage by a comparator, and the output of each element was read.
[0210]
As a result, in the MRAM using the MR element of Example c3, good element output was obtained as in the case of the single magnetic memory. However, in the MRAM using the MR element of the conventional example c0A, no element output was obtained. I couldn't. Therefore, the MR element of the conventional example c0A cannot withstand the heat treatment at 400 ° C., whereas the MR element of the example c3 has sufficient heat resistance even at the heat treatment of 400 ° C. Understand.
[0211]
【The invention's effect】
As described above, according to the present invention, by controlling the average grain size of the magnetization stable layer and the distance between the magnetization stable layer and the nonmagnetic layer, a high-output MR element having excellent heat resistance can be obtained. be able to. Further, by using the MR element of the present invention, it is possible to obtain a magnetic head, a magnetic memory element, and a magnetic recording device having excellent heat resistance.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a magnetoresistive element according to the present invention.
FIG. 2 is a sectional view showing an example of a magnetoresistance effect element according to the present invention.
FIG. 3 is a cross-sectional view illustrating an example of a magnetoresistive element according to the present invention.
FIG. 4 is a cross-sectional view illustrating an example of a magnetoresistance effect element according to the present invention.
FIG. 5 is a cross-sectional view for explaining an example of a state of crystal grains in the magnetoresistance effect element of the present invention.
FIG. 6 is a cross-sectional view illustrating an example of a magnetoresistance effect element according to the present invention.
FIG. 7 is a cross-sectional view showing an example of a magnetoresistance effect element according to the present invention.
FIG. 8 is a cross-sectional view showing an example of a magnetoresistance effect element according to the present invention.
FIG. 9 is a cross-sectional view illustrating an example of a magnetoresistance effect element according to the present invention.
FIG. 10 is a cross-sectional view illustrating an example of a magnetoresistance effect element according to the present invention.
FIG. 11 is a cross-sectional view illustrating an example of a magnetoresistive element according to the present invention.
FIG. 12 is a cross-sectional view illustrating an example of a magnetoresistive element according to the present invention.
FIG. 13 is a cross-sectional view illustrating an example of a magnetoresistance effect element according to the present invention.
FIG. 14 is a cross-sectional view illustrating an example of a magnetoresistance effect element according to the present invention.
FIG. 15 is a cross-sectional view illustrating an example of a magnetoresistive element according to the present invention.
FIG. 16 is a cross-sectional view illustrating an example of a magnetoresistive element according to the present invention in which electrodes are further arranged.
FIG. 17 is a schematic view showing an example of a magnetic head according to the present invention.
FIG. 18 is a schematic view showing an example of a magnetic head according to the present invention.
FIG. 19 is a schematic view showing an example of a magnetic recording device according to the present invention.
FIG. 20 is a schematic view showing an example of a magnetic memory according to the present invention.
FIG. 21 is a schematic view showing an example of a magnetic memory according to the present invention.
FIG. 22 is a schematic diagram showing a basic example of the operation of the magnetic memory according to the present invention.
FIG. 23 is a schematic view showing a basic example of the operation of the magnetic memory according to the present invention.
FIG. 24 is a schematic view showing a basic example of the operation of the magnetic memory according to the present invention.
FIG. 25 is a diagram illustrating a relationship between a heat treatment temperature and an MR ratio, measured according to an example.
FIG. 26 is a diagram showing the size of crystal grains on the surface of the magnetization stable layer measured according to the example.
FIG. 27 shows a film thickness X of a particle size control layer measured according to an example.₁FIG. 3 is a diagram showing a relationship between the MR ratio and the average particle diameter D.
FIG. 28 is a diagram illustrating a relationship between a distance H, an MR ratio, and an average particle diameter D, measured according to an example.
FIG. 29 is a diagram illustrating a relationship between a distance H, an MR ratio, and an average particle diameter D, measured according to an example.
FIG. 30 is a diagram illustrating a relationship between a distance H and an average particle diameter D measured according to an example.
FIG. 31 is a diagram showing minor curves of an MR element before and after heat treatment, measured according to an example.
FIG. 32 is a diagram showing minor curves of an MR element before and after heat treatment, measured according to an example.
[Explanation of symbols]
1,11,12,13 Non-magnetic layer
2, 3, 31, 32 magnetic layer
4 Magnetic stable layer
5 Free magnetic layer
6, 61, 62 ° fixed magnetic layer
7 Particle size control layer
8 Diffusion control layer
9mm board
41 ° soft magnetic layer
42 ° high coercivity magnetic layer
43 antiferromagnetic layer
101 crystal grain
102 grain boundary
301 non-magnetic film
302, 303 magnetic film
310 laminated ferrilayer
501 interlayer insulation film
502 upper electrode
503 lower electrode
504 substrate
505, 520, 531, 601, 601a, 701 MR element
511 head
512 writing head
513 playback head
514 coil
515 upper recording core
516mm upper shield
517 recording gap
521 playback gap
522 lower shield
523 electrode
532mm yoke
541 magnetic head
542 drive unit
543 magnetic recording medium
544 signal processing unit
545 ° magnetic recording device
602, 703 bit line
603 @ word line
604 connecting line
705 ° switch element
706 nonlinear element

Claims (25)

A magnetoresistive element in which a multilayer structure including a structure in which a pair of magnetic layers is stacked via a nonmagnetic layer is formed on a substrate, and the resistance of the magnetic layers differs depending on the relative angle of the magnetization direction of the two magnetic layers. hand,
A magnetoresistive element, further comprising a magnetization stable layer for changing a magnetization reversal magnetic field of the magnetic layer, wherein the magnetization stable layer satisfies a relationship represented by the following equation.
1 nm ≦ D <10 nm
And
D ≧ 2 × H or H ≧ 1.4 × D
Here, D is the average grain size of the crystal grains of the material constituting the magnetization stable layer, and H is the distance between the magnetization stable layer and the nonmagnetic layer. A magnetoresistive element in which a multilayer structure including a structure in which a pair of magnetic layers is stacked via a nonmagnetic layer is formed on a substrate, and the resistance of the magnetic layers differs depending on the relative angle of the magnetization direction of the two magnetic layers. hand,
A magnetoresistive element, further comprising a magnetization stable layer for changing a magnetization reversal magnetic field of the magnetic layer, wherein the magnetization stable layer satisfies a relationship represented by the following equation.
D ≧ 10 nm
Here, D is the average grain size of the crystal grains of the material constituting the magnetization stable layer. The magnetoresistive element according to claim 1, wherein the magnetization stable layer includes a high coercivity magnetic material. 3. The magnetoresistive element according to claim 1, wherein the magnetization stable layer includes an antiferromagnetic material. The magnetoresistance effect element according to claim 4, wherein the antiferromagnetic material contains a Mn alloy. The magnetoresistive element according to claim 5, wherein the Mn alloy has a composition represented by the formula Mn-Z.
Here, Z is at least one element selected from Pt, Pd, Fe, Ir, Ni, Co, Rh, O, C, F, N and B. The Mn alloy is composed of a crystal having a relatively high Mn content (crystal A) and a crystal having a relatively low Mn content (crystal B), and the Mn content of the crystal A is 60 at% or more, and 7. The magnetoresistive element according to claim 6, wherein the volume ratio of the crystal A is 25 vol% or less of the magnetization stable layer. 3. The magnetoresistive element according to claim 1, wherein the magnetic layer has a structure in which a pair of magnetic films are stacked via a nonmagnetic film. 9. The magnetoresistive element according to claim 8, wherein the nonmagnetic film is made of at least one element selected from Cr, Cu, Ag, Au, Ru, Ir, Re and Os. 3. The magnetoresistive element according to claim 1, wherein the nonmagnetic layer is made of a conductive material. The magnetoresistive element according to claim 10, wherein the conductive material contains at least one element selected from Cu, Au, Ag, Ru, and Cr. 3. The magnetoresistive element according to claim 1, wherein the nonmagnetic layer is made of an insulating material. 13. The magnetoresistive element according to claim 12, wherein the insulating material includes an oxide, nitride or oxynitride of Al. 3. The magnetoresistive element according to claim 1, further comprising a grain size control layer that changes a grain size of a crystal grain of a material contained in the magnetization stable layer. The magnetoresistive element according to claim 14, wherein the grain size control layer is disposed between the magnetization stable layer and the substrate. 15. The magnetoresistive element according to claim 14, wherein the grain size control layer is disposed so as to be in contact with the magnetization stable layer. 3. The magnetoresistive element according to claim 1, further comprising a diffusion control layer for suppressing diffusion of an element contained in the magnetization stable layer. 18. The magnetoresistive element according to claim 17, wherein the diffusion control layer is disposed between the magnetization stable layer and the substrate. The magnetoresistance effect element according to claim 17, wherein the diffusion control layer is disposed between the magnetization stable layer and the nonmagnetic layer. 18. The magnetoresistive element according to claim 17, wherein the diffusion control layer is arranged so as to be in contact with the magnetization stable layer. The magnetoresistive element according to claim 17, wherein the diffusion control layer includes a ferromagnetic material having a composition represented by the formula MX.
Here, M is at least one element selected from Fe, Co and Ni, and X is IVa to VIIa, VIII, Ib, lanthanoid, Al, Si, Sc, Y, Zn, Ga, At least one non-magnetic element selected from Ge, B, C, N, O, P and S. 22. A magnetoresistive element according to claim 1, further comprising a shield for restricting introduction of a magnetic field other than a magnetic field to be detected by the magnetoresistive element into the element. Magnetic head. A magnetic head comprising: the magnetoresistive element according to claim 1; and a yoke for introducing a magnetic field to be detected into the magnetoresistive element. The magnetoresistive element according to any one of claims 1 to 21, an information recording conductor line for recording information on the magnetoresistive element, and an information reading conductor line for reading the information. A magnetic memory comprising: A magnetic recording device comprising the magnetic head according to claim 22.

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