JP4944315B2 - Magnetoresistive film, memory element including the same, and memory using the same - Google Patents

Magnetoresistive film, memory element including the same, and memory using the same Download PDF

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JP4944315B2
JP4944315B2 JP2001245423A JP2001245423A JP4944315B2 JP 4944315 B2 JP4944315 B2 JP 4944315B2 JP 2001245423 A JP2001245423 A JP 2001245423A JP 2001245423 A JP2001245423 A JP 2001245423A JP 4944315 B2 JP4944315 B2 JP 4944315B2
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film
magnetic
magnetization
magnetoresistive
magnetic film
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JP2003060261A (en
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貴司 池田
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Canon Inc
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Canon Inc
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Priority to TW091106511A priority patent/TW560095B/en
Priority to CN021198284A priority patent/CN1384503B/en
Priority to DE60223440T priority patent/DE60223440T2/en
Priority to KR10-2002-0017937A priority patent/KR100498998B1/en
Priority to US10/113,983 priority patent/US6829121B2/en
Priority to EP02007503A priority patent/EP1248264B1/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y25/00Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00Thin magnetic films, e.g. of one-domain structure
    • H01F10/32Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
    • H01F10/324Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Nanotechnology (AREA)
  • Power Engineering (AREA)
  • Hall/Mr Elements (AREA)
  • Mram Or Spin Memory Techniques (AREA)
  • Magnetic Heads (AREA)
  • Thin Magnetic Films (AREA)
  • Semiconductor Memories (AREA)

Description

【0001】
【発明の属する技術分野】
本発明は、垂直磁化膜の磁化反転磁界を低減させる方法を用いた磁気抵抗効果膜、それを備えたメモリ素子及びそれを用いたメモリに関する。
【0002】
【従来の技術】
近年、固体メモリである半導体メモリは情報機器に多く用いられ、DRAM、FeRAM、フラッシュEEPROM等その種類も様々である。これら半導体メモリの特性は一長一短であり、現在の情報機器において要求されるスペックのすべてを満たすメモリが存在しない。例えば、DRAMは記録密度が高く書き換え可能回数も多いが、揮発性であり電源を切ると情報は消えてしまう。また、フラッシュEEPROMは不揮発であるが消去の時間が長く、情報の高速処理には不向きである。
【0003】
上記のような半導体メモリの現状に対して、磁気抵抗効果を用いたメモリ(MRAM)は、記録時間、読み出し時間、記録密度、書き換え可能回数、消費電力等において多くの情報機器から求められるスペックをすべて満たすメモリとして有望である。特にスピン依存トンネル磁気抵抗(TMR)効果を利用したMRAMは、大きな読み出し信号が得られることから、高記録密度化あるいは高速読み出しに有利であり、近年の研究報告においてMRAMとしての実現性が実証されている。
【0004】
MRAMの素子として用いられる磁気抵抗効果膜の基本構成は、非磁性層を介して磁性層が隣接して形成されたサンドイッチ構造である。非磁性膜として良く用いられる材料としてCuやAl2O3が挙げられる。磁気抵抗効果膜において非磁性層にCu等のような導体を用いたものを巨大磁気抵抗効果膜(GMR膜)といい、Al2O3などの絶縁体を用いたものをスピン依存トンネル磁気抵抗効果膜(TMR膜)という。一般にTMR膜はGMR膜に比べて大きな磁気抵抗効果を示す。
【0005】
図13(a)に示すように二つの磁性層の磁化方向が平行であると磁気抵抗効果膜の電気抵抗は比較的小さく、図13(b)に示すように磁化方向が反平行であると電気抵抗は比較的大きくなる。したがって、一方の磁性層を記録層、他方を読み出し層とし、上記の性質を利用することで情報の読み出しが可能である。例えば非磁性層12の上部に位置する磁性層13を記録層、下部に位置する磁性層14を読み出し層とし、記録層の磁化方向が右向きの場合を『1』、左向きの場合を『0』とする。図14(a)に示すように両磁性層の磁化方向が右向きの場合、磁気抵抗効果膜の電気抵抗は比較的小さく、図14(b)に示すように読み出し層の磁化方向が右向きでかつ記録層の磁化方向が左向きであると電気抵抗は比較的大きい。また、図14(c)に示すように読み出し層の磁化方向が左向きでかつ記録層の磁化方向が右向きであると電気抵抗は比較的大きく、図14(d)に示すように両磁性層の磁化方向が左向きの場合電気抵抗は比較的小さい。つまり、読み出し層の磁化方向が右向きに固定されている場合に、電気抵抗が大きければ、記録層には『0』が記録されていることになり、電気抵抗が小さければ、『1』が記録されていることになる。あるいは、読み出し層の磁化方向が左向きに固定されている場合に、電気抵抗が大きければ、記録層には『1』が記録されていることになり、電気抵抗が小さければ、『0』が記録されていることになる。
【0006】
MRAMの記録密度を高くするために、素子サイズを小さくしていくと、面内磁化膜を使用したMRAMは反磁界あるいは端面の磁化のカーリングといった影響から、情報を保持できなくなるという問題が生じる。この問題を回避するためには、例えば磁性層の形状を長方形にすることが挙げられるが、この方法では素子サイズが小さくできないために記録密度の向上があまり期待されない。そこで、例えば特開平11-213650号公報で述べられているように垂直磁化膜を用いることにより上記問題を回避しようとする提案がなされている。この方法では素子サイズが小さくなっても反磁界は増加しないので、面内磁化膜を用いたMRAMよりも小さなサイズの磁気抵抗効果膜が実現可能である。
【0007】
垂直磁化膜を用いた磁気抵抗効果膜は、面内磁化膜を用いた磁気抵抗効果膜と同様に、二つの磁性層の磁化方向が平行であると磁気抵抗効果膜の電気抵抗は比較的小さく、磁化方向が反平行であると電気抵抗は比較的大きくなる。非磁性層22の上部に位置する磁性層23を記録層、下部に位置する磁性層21を読み出し層とし、記録層の磁化方向が上向きの場合を『1』、下向きの場合を『0』とする。図15(a)に示すように両磁性層の磁化方向が上向きの場合、磁気抵抗効果膜の電気抵抗は比較的小さく、図15(c)に示すように読み出し層の磁化方向が下向きでかつ記録層の磁化方向が上向きであると電気抵抗は比較的大きくなる。したがって、『1』が記録された状態で読み出し層の磁化方向が上向きとなるように磁界を印加した後、さらに読み出し層の磁化方向が下向きとなるように磁界を印加すると、磁気抵抗効果膜の電気抵抗は大きくなるように変化し、この変化から『1』を読み出すことが可能である。ただし、読み出しのときに印加する磁界は記録層の磁化方向が変化しないような大きさである。また、図15(b)に示すように読み出し層の磁化方向が上向きでかつ記録層の磁化方向が下向きであると電気抵抗は比較的大きくなり、図15(d)に示すように両磁性層の磁化方向が下向きの場合電気抵抗は比較的小さくなる。したがって、『0』が記録されているときには、読み出しの操作を行うと電気抵抗が小さくなるように変化するので『0』を読み出すことが可能である。
【0008】
【発明が解決しようとする課題】
垂直磁化膜としては、Gd、Dy、Tb等の希土類金属から選ばれる少なくとも1種類の元素とCo、Fe、Ni等の遷移金属から選ばれる少なくとも1種類の元素の合金膜や人工格子膜、Co/Pt等遷移金属と貴金属の人工格子膜、CoCr等の膜面垂直方向の結晶磁気異方性を有する合金膜が主として挙げられる。垂直磁化膜の磁化反転磁界は、一般に遷移金属による面内磁気異方性を有するそれよりも大きく、例えば面内磁化膜であるパーマロイの磁化反転磁界が数百A/m程度であるのに対し、垂直磁化膜であるCo/Pt人工格子膜では数十kA/m程度と著しく大きい。希土類金属と遷移金属の合金膜は、希土類金属の副格子磁化と遷移金属の副格子磁化が反平行に向くため、膜組成によって見かけ上の磁化の大きさが異なる。したがってその磁化反転磁界は組成により異なる。GdFe合金膜は、希土類金属と遷移金属の合金膜の中でも比較的磁化反転磁界は小さいが、磁化曲線の角型比が1から小さくなり始める臨界組成付近で通常数千A/m程度の磁化反転磁界を有する。
【0009】
垂直磁化膜を用いた磁気抵抗効果膜でセンサーやメモリ等を構成した場合、上記の理由から大きな磁界を印加しなければ動作しない。したがって、例えばセンサーにおいては浮遊磁界を磁気抵抗効果膜の磁性層に集中させる必要があり、メモリにおいては大きな磁界を発生させる工夫が必要になる。メモリに印加する磁界は一般的に導線に電流を流し発生させるが、特に携帯端末に用いるメモリの場合、電源容量の制約から大きな電流を流すことは好ましくない。このため、例えば磁気抵抗効果膜からなるメモリ素子の周りに磁界を発生させるための導線を巻きつけるなどの対応が必要になる。しかし、このような対応は磁気抵抗効果膜周辺の構造や電気回路を煩雑にしてしまうため作成が困難になり、歩留まりの低下やコストの著しい増加を招いてしまうという問題がある。
【0010】
本発明は、この点に鑑み、垂直磁化膜の磁化反転磁界を低減させ、作成が容易で歩留まりの低下やコストの著しい増加を招くことのない磁気抵抗効果膜を提供することさらには消費電力の少ないメモリを提供することを目的とする。
【0011】
【課題を解決するための手段】
本発明の磁気抵抗効果膜は、
非磁性膜が磁性膜に挟まれている構造を持った磁気抵抗効果膜において、磁性膜の少なくとも一方が垂直磁化膜であり、垂直磁化膜に接して,且つ非磁性膜には接しない位置に、磁化容易軸が膜面垂直方向から傾いている磁性膜を有する。
【0012】
また、磁性膜の少なくとも一方の磁化容易軸が膜面垂直方向から傾いていてもよい。
【0013】
また、磁性膜と磁化容易軸が膜面垂直方向から傾いている磁性膜とが交換結合していてもよい。
また、更に、垂直磁化膜と非磁性膜の間に垂直磁化膜よりもスピン分極率の大きな層が挿入されていてもよい。
【0014】
また、垂直磁化膜とスピン分極率の大きな層が交換結合していてもよい。
【0015】
また、磁化容易軸が膜面垂直方向から傾いている第一の磁性膜と、第二の磁性膜と、非磁性膜と、第三の磁性膜と、磁化容易軸が膜面垂直方向から傾いている第四の磁性膜とがこの順に形成され、少なくとも第二の磁性膜もしくは第三の磁性膜のどちらか一方が垂直磁化膜であり、第一の磁性膜と第二の磁性膜、および第三の磁性膜と第四の磁性膜がそれぞれ交換結合していてもよい。
【0016】
また、第二の磁性膜もしくは第三の磁性膜の少なくとも一方の磁化容易軸が膜面垂直方向から傾いていてもよい。
【0017】
また、第二の磁性膜と非磁性膜との間に第二の磁性膜よりもスピン分極率の大きな層が形成されていてもよい。
【0018】
また、更に、第三の磁性膜と非磁性膜との間に第三の磁性膜よりもスピン分極率の大きな層が形成されていてもよい。
【0019】
また、スピン分極率の大きな層と第二の磁性膜、及びスピン分極率の大きな層と第三の磁性膜が交換結合していてもよい。
【0020】
また、スピン分極率の大きな層が粒形状であってもよい。
【0021】
また、磁化容易軸が膜面垂直方向から傾いている磁性膜の磁化が、4kA/m以下の大きさの磁界によって、膜面垂直方向に向いてもよい。
【0022】
また、磁化容易軸が膜面垂直方向から傾いた方向に向いている磁性膜の磁化が、垂直磁化膜と交換結合している状態において、少なくとも部分的に膜面垂直方向に対して傾いていてもよい。
【0023】
また、垂直磁化膜がフェリ磁性体であってもよい。
【0024】
また、フェリ磁性体が希土類金属と遷移金属の合金であってもよい。
【0025】
また、希土類金属と遷移金属の合金が非晶質であってもよい。
【0026】
また、フェリ磁性体が希土類金属と遷移金属の人工格子膜であってもよい。
【0027】
また、希土類金属がGd、Tb、Dyから選ばれる1種類以上の元素であり、遷移金
属がFe、Co、Niから選ばれる1種類以上の元素であってもよい。
【0028】
また、非磁性膜が絶縁体であってもよい。
【0029】
本発明のメモリ素子は、
上述の磁気抵抗効果膜を備えたメモリ素子において、磁気抵抗効果膜の膜面垂直方向に磁界を印加する手段と、磁気抵抗効果膜の電気抵抗を検出する手段とを備えている。
【0030】
また、磁界を印加する手段が導線であってもよい。
【0031】
また、更に、磁気抵抗効果膜の膜面垂直方向から傾いた方向に磁界を印加する手段を備えていてもよい。
【0032】
本発明のメモリは、
上述の磁気抵抗効果膜をメモリ素子として用いたメモリにおいて、情報の記録時に、非磁性膜を挟んでいる磁性膜のうち、磁化容易軸が膜面垂直方向から傾いている磁性膜と接して設けられている磁性膜の磁化方向を変化させ、他方の磁性膜の磁化方向は変化させずに情報の記録再生を行なう。
【0033】
また、非磁性膜に接して形成されている磁性膜のうち、零磁場中で磁化が膜面垂直方向に向いている磁性膜を記録層とし、磁化が膜面垂直方向から傾いている磁性膜を読み出し層としてもよい。
【0034】
また、記録あるいは読み出し時に印加される磁界に対して、非磁性膜に隣接して形成されている磁性膜のうち、非磁性膜の一方の膜面に接して形成されている磁性膜の磁化は反転することなく、非磁性膜の他方の膜面に接して形成されている磁性膜の磁化は反転してもよい。
【0035】
また、磁気抵抗効果膜を複数配列し、所望の磁気抵抗効果膜に選択的に記録する手段と、所望の磁気抵抗効果膜に記録された情報を選択的に読み出す手段とを備えてもよい。
【0036】
従って、本発明の磁気抵抗効果膜は、比較的小さな磁界で磁化反転可能であり、特にこの磁気抵抗効果膜を用いたメモリは消費電力を少なくすることが可能である。
【0037】
【発明の実施の形態】
本発明の磁気抵抗効果膜の一例を図1に示す。無磁場中でかつ他の磁性体との交換力が働いていない状態で磁化が膜面垂直方向から傾いた方向に向いている磁性膜、すなわち磁化容易軸が膜面垂直方向から傾いている第一の磁性膜111、垂直磁化膜である第二の磁性膜112、非磁性膜113および垂直磁化膜である第三の磁性膜114が順次形成されている。第一の磁性膜111と第二の磁性膜112は交換結合している。第二の磁性膜112の磁化は、零磁場において少なくとも非磁性膜113との界面付近では膜面垂直方向に向いているか、あるいは膜面垂直方向に磁界を印加したときには容易に膜面垂直方向に向くようにしておく。MRAMにおいて、導線に流す電流密度の制限から、メモリ素子に印加可能な磁界の大きさは4kA/m以下にすることが好ましい。従って零磁場中で膜面垂直方向から傾いている磁化は4kA/m以下の大きさの磁界を印加することにより垂直方向に向くようにしておく。垂直磁化膜に無磁場中でかつ他の磁性体との交換力が働いていない状態で磁化が膜面垂直方向から傾いた方向に向いている磁性膜を交換結合させると、垂直磁化膜は、垂直磁気異方性が見かけ上減少する。したがって、膜面垂直方向での磁化反転磁界を小さくすることが可能である。
【0038】
垂直磁化膜と面内磁化膜の交換結合膜を用いた磁気抵抗効果膜が、特開2000-306374号公報において開示されている。本発明がこれに対して大きく異なる点は、磁化が膜面垂直方向から傾いた方向に向いている磁性膜を配する位置である。特開2000-306374号公報では、大きな磁気抵抗効果を得ることを目的とし、大きなスピン分極率を有する磁性膜を非磁性膜に接する様に形成することを手段としている。大きなスピン分極率を有する磁性膜に面内磁化膜が用いられているが、該磁性膜の磁化は膜面垂直方向に向いている必要があり、これは接して形成されている垂直磁化膜との交換結合力によって達成されている。
【0039】
これに対して本発明は、膜面垂直方向に印加する磁界に対する磁化反転磁界を減少させることを目的としており、無磁場中でかつ他の磁性体との交換力が働いていない状態で磁化が膜面垂直方向から傾いた方向に向いている磁性膜は非磁性膜とは接しておらず、該磁性膜の磁化は膜面垂直方向に向いている必要は無い。
【0040】
無磁場中でかつ他の磁性体との交換力が働いていない状態で磁化が膜面垂直方向から傾いた方向に向いている磁性膜を非磁性膜に接する様に形成しても接しないように形成しても、該磁性膜と垂直磁化膜の交換結合膜の磁化反転磁界は、垂直磁化膜単層の場合のそれよりも減少する。しかし、膜面垂直方向の磁化反転は、磁化が膜面垂直方向から傾いた方向に向いている磁性膜の膜厚に依存しており、磁性膜の膜厚は磁化反転磁界の大きさによって決められる。特開2000-306374号公報では、上記のように磁化を膜面垂直方向に向ける必要があるために面内磁化膜の膜厚を厚くすることができず、面内磁化膜の膜厚を2nm以下にする必要があるために、磁化反転磁界の減少量はあまり期待できない。これに対して本発明の磁気抵抗効果膜では、磁化が膜面垂直方向から傾いた方向に向いている磁性膜の磁化を膜面垂直方向に向ける必要がないので、該磁性膜の膜厚を比較的厚くすることが可能であり、そのために膜面垂直方向での磁化反転磁界を十分に小さくすることが容易である。
【0041】
上述したように図1に記載の膜構成が本発明の実施の形態の一例として挙げられる。第二の磁性膜112と交換結合している状態で、第一の磁性膜111の磁化は膜面垂直方向に向いていても、膜面垂直方向から傾いていても構わない。ただし、磁化が膜面垂直方向から傾いている磁気抵抗効果膜をメモリ素子として用いる場合、第三の磁性膜114の磁化と第二の磁性膜112の磁化はどちらも反転可能であることが必要であり、第三の磁性膜114を記録層、第二の磁性膜112を読み出し層とする。導線に電流を流し、この電流によって発生する磁界で記録を行う場合、一般に4 kA/mよりも大きな磁界を発生させることは難しく、したがって、第三の磁性膜114への記録は4 kA/m以下の磁界で行われることが好ましく、読み出しの際には、膜面垂直方向から傾いている第二の磁性膜112の磁化が、第三の磁性膜114の磁化の反転磁界よりも小さい磁界によって膜面垂直方向に向くことが好ましい。また、第二の磁性膜112の磁化は、第三の磁性膜114の磁化よりも小さな磁界によって反転する。
【0042】
垂直磁化膜としては、上述のようにGd、Dy、Tb等の希土類金属から選ばれる少なくとも1種類の元素とCo、Fe、Ni等の遷移金属から選ばれる少なくとも1種類の元素の合金膜や人工格子膜、Co/Pt等遷移金属と貴金属の人工格子膜、CoCr等の膜面垂直方向の結晶磁気異方性を有する合金膜が主として使用可能である。無磁場中でかつ他の磁性体との交換力が働いていない状態で磁化が膜面垂直方向から傾いた方向に向いている磁性膜としては、上記の垂直磁気異方性を有する磁性膜と同様の材料を用いて、Ku−2πMs2<0となるように成膜条件を調整することにより得られる。これによって磁化容易軸が膜面垂直方向から傾いた磁性膜を得ることができる。ここでKuは垂直磁気異方性エネルギー定数、Msは飽和磁化の大きさである。また、Co、Fe、Ni等の遷移金属から選ばれる1種類の元素からなる膜、あるいは2種類以上の元素からなる合金膜を用いて成る面内磁化膜も使用可能である。
【0043】
非磁性膜113としては、CuやCr等の導体あるいはAl2O3やNiO等の絶縁体が使用可能である。非磁性膜113に絶縁体を用いた場合、比較的大きな磁気抵抗変化が得られるので、メモリ素子として利用する場合には好ましい。
【0044】
図1に示す膜構成の磁気抵抗効果膜をメモリ素子として用いる場合、第二の磁性膜112の磁化は印加される磁界によって反転可能であり、第三の磁性膜114の磁化は反転可能であっても不可能であってもどちらでも良い。ただし、第三の磁性膜114の磁化が反転不可能である場合は、読み出しの際に、記録されている情報を破壊しないために、磁化方向を変化させることなく、素子の電圧を直接読み取ることが好ましい。第三の磁性膜114の磁化が反転可能である場合には、比較的磁化反転磁界の小さな、第一の磁性膜111と第二の磁性膜112の交換結合膜を読み出し層とし、比較的磁化反転磁界の大きな第三の磁性膜114を記録層とすることが可能であり、第二の磁性膜112の磁化方向を反転させることにより生じる素子の電圧変化を読み取ることによって、記録されている情報を非破壊で読み出すことが可能である。
【0045】
図2は本発明の実施の形態の一例である膜構成を模式的に示す断面図であり、第四の磁性膜115が形成されている点が図1に示す膜構成と異なる。第四の磁性膜115は、無磁場中でかつ他の磁性体との交換力が働いていない状態で磁化が膜面垂直方向から傾いた方向に向いている磁性膜であり、第三の磁性膜114と交換結合している。つまり、第一の磁性膜111と同様に垂直磁化膜の磁化反転磁界を小さくする働きをするものである。このような構成にすることによって、第二の磁性膜112および第三の磁性膜114のどちらも小さな印加磁界で磁化反転可能である。ただし、第二の磁性膜112の磁化反転磁界と第三の磁性膜114の磁化反転磁界の大きさは異なる。このような構成の磁気抵抗効果膜をメモリとして用いる場合、第一の磁性膜111と第二の磁性膜112の交換結合膜と第三の磁性膜114と第四の磁性膜115の交換結合膜のうち、磁化反転磁界の比較的小さな方を読み出し層、磁化反転磁界の比較的大きな方を記録層とする。磁化反転磁界の大きさは、各磁性膜の組成、膜厚あるいは成膜条件等によって調節することが可能である。
【0046】
さらに図3のように非磁性膜113と磁性膜の界面にスピン分極率の大きな材料からなる磁性膜116や117を形成し、磁気抵抗を大きくすることも可能である。図3においては両界面にそのような膜を形成しているが、どちらか一方のみ形成しても良い。界面に形成される磁性膜116や117は磁化が膜面垂直方向から傾いた方向に向いているものでも垂直磁化膜でもどちらでも構わないが、それぞれ第二の磁性膜112および第三の磁性膜114と交換結合した状態では、非磁性膜113との界面付近の磁化は膜面垂直に向いている必要がある。
【0047】
また、磁性膜116や磁性膜117は、粒形状であっても良い。
【0048】
上記の本発明の磁気抵抗効果膜において、非磁性膜はCu等の金属でも良いし、Al2O3等の誘電体であっても良いが、メモリとして用いる場合、非磁性膜を誘電体とした方が磁気抵抗変化が大きいので好ましい。
【0049】
上記のようないずれかの膜構成の磁気抵抗効果膜を複数個並べて配し、所望の一素子にのみ比較的大きな磁界を印加することにより、選択的に記録が可能なメモリセルとすることができる。
【0050】
【実施例】
(実施例−1)
図4は本発明の磁気抵抗効果膜を模式的に示した断面図である。基板001としてSiウエハーを用い、この表面を酸化処理し約1μmのSiO2膜002が形成されている。SiO2膜002上部に第一の磁性膜111として面内磁化膜である5nmの膜厚のFe膜、第二の磁性膜112として垂直磁化膜である30nmの膜厚のGd20Fe80膜、非磁性膜113として2nmの膜厚のAl2O3膜、第三の磁性膜114として垂直磁化膜である10nmのTb22Fe78膜、保護膜118として5nmのPt膜を順次形成した。ここで、Fe膜とGd20Fe80膜は交換結合しており、Pt膜は磁性膜の酸化等の腐食を防ぐための保護膜である。Gd20Fe80膜およびTb22Fe78膜はどちらも遷移金属副格子磁化優勢である。次に得られた多層膜の上部に1μm角のレジスト膜を形成し、ドライエッチングによってレジストに覆われていない部分のPt膜およびTb22Fe78膜を除去した。エッチング後15nmの膜厚のAl2O3膜を成膜し、さらにレジストおよびその上部のAl2O3膜を除去し、上部電極とFe膜およびGd20Fe80膜からなる下部電極との短絡を防ぐための絶縁膜121を形成した。その後、リフトオフ法によって上部電極122をAl膜により作成し、上部電極からずれた位置のAl2O3膜を除去して測定回路を接続するための電極パットとした。さらに得られた磁気抵抗効果膜は膜面垂直方向に2MA/mの磁界を印加し、Tb22Fe78膜の磁化を印加磁界方向に向け着磁を行った。ただし、1cm角のTb22Fe78膜の保磁力は1.6MA/mと大きな値を示し、得られた磁気抵抗効果膜の保磁力も同程度の大きな値を示すと予想される。
【0051】
磁気抵抗効果膜の上部電極と下部電極に定電流電源を接続してGd20Fe80膜とTb22Fe78膜の間のAl2O3膜を電子がトンネルするように一定電流を流す。磁気抵抗効果膜の膜面に垂直方向に磁界を印加し、その大きさと方向を変えることにより磁気抵抗効果膜の電圧の変化(磁気抵抗曲線)を測定した。その結果を図8に示す。この測定結果によると磁化反転は約3kA/mであった。
【0052】
(実施例−2)
図6は本発明の磁気抵抗効果膜を模式的に示した断面図である。基板001としてSiウエハーを用い、この表面を酸化処理し約1μmのSiO2膜002が形成されている。SiO2膜002上部に第一の磁性膜111として面内磁化膜である3nmの膜厚のFe膜、第二の磁性膜112として垂直磁化膜である50nmの膜厚のGd25Fe75膜、第二の磁性膜よりも大きなスピン分極率を示す第五の磁性膜116として面内磁化膜である1nmの膜厚のCo50Fe50膜、非磁性膜113として2nmの膜厚のAl2O3膜、さらに第三の磁性膜よりも大きなスピン分極率を示す第六の磁性膜117として面内磁化膜である1nmの膜厚のCo50Fe50膜、第三の磁性膜114として垂直磁化膜である30nmの膜厚のTb25Fe75膜、第四の磁性膜115として面内磁化膜である3nmの膜厚のFe膜、保護膜118として5nmのPt膜を順次形成した。ここで、Fe膜とGd25Fe75膜、Gd25Fe75膜とCo50Fe50膜はそれぞれ交換結合しており、さらにCo50Fe50膜とTb25Fe75膜、Tb25Fe75膜とFe膜はそれぞれ交換結合している。Gd25Fe75膜とTb25Fe75膜はどちらも希土類金属副格子磁化優勢である。2層のCo50Fe50膜はGd25Fe75膜やTb25Fe75膜よりもスピン分極率が大きく、その磁化の方向は交換結合力により膜面垂直方向に向いている。Pt膜は磁性膜の酸化等の腐食を防ぐための保護膜である。次に得られた多層膜の上部に1μm角のレジスト膜を形成し、ドライエッチングによってレジストに覆われていない部分のPt膜およびTb25Fe75膜を除去した。エッチング後39nmの膜厚のAl2O3膜を成膜し、さらにレジストおよびその上部のAl2O3膜を除去し、上部電極とFe膜およびGd25Fe75膜からなる下部電極との短絡を防ぐための絶縁膜121を形成した。その後、リフトオフ法によって上部電極122をAl膜により作成し、上部電極からずれた位置のAl2O3膜を除去して測定回路を接続するための電極パットとした。
【0053】
磁気抵抗効果膜の上部電極と下部電極に定電流電源を接続してGd25Fe75膜とTb25Fe75膜の間のAl2O3膜を電子がトンネルするように一定電流を流す。磁気抵抗効果膜の膜面に垂直方向に磁界を印加し、その大きさと方向を変えることにより磁気抵抗効果膜の電圧の変化を測定した。その結果を図7に示す。磁化反転は約2.5kA/mと3.8kA/mで生じている。
【0054】
(実施例−3)
実施例-2で用いた磁気抵抗効果膜101、102、103、104、105、106、107、108、109をメモリ素子として3行3列に配列した場合のメモリセルの電気回路図を図8および図9に示す。図8は磁気抵抗効果膜に印加する磁界を発生させるための回路であり、図9は磁気抵抗効果膜の抵抗変化を検出するための回路である。
【0055】
任意の素子の磁性膜の磁化を選択的に反転させる方法について説明する。例えば、磁気抵抗効果膜105の磁化を選択的に反転させる場合、トランジスタ212、217、225、220をONにし、その他のトランジスタはOFFにしておく。このようにすると電流は導線312、313、323、322を流れそれらの周りに磁界を発生させる。したがって磁気抵抗効果膜105にのみ4つの導線から同方向の磁界が印加され、これらの合成磁界が素子の磁性膜の磁化反転磁界よりも僅かに大きくなるように調整しておけば、選択的に磁気抵抗効果膜105の磁化のみ反転させることが可能である。また上下逆方向の磁界を磁気抵抗効果膜105に印加する場合はトランジスタ213、216、224、221をONにし、その他のトランジスタはOFFにしておく。このようにすると電流は導線312、313、323、322を先程とは逆の方向に流れ磁気抵抗効果膜105へは逆方向の磁界が印加される。
【0056】
次に読み出し時の動作を説明する。例えば、磁気抵抗効果膜105に記録された情報を読み出す場合、トランジスタ235およびトランジスタ241をONにする。すると電源412、固定抵抗100および磁気抵抗効果膜105が直列に接続された回路となる。したがって、電源電圧は固定抵抗100の抵抗値と磁気抵抗効果膜105の抵抗値の割合でそれぞれの抵抗に分圧される。電源電圧は固定されているので磁気抵抗効果膜の抵抗値が変化するとそれにしたがって、磁気抵抗効果膜にかかる電圧は異なる。この電圧値をセンスアンプ500で読み出す。ここで読み出し方法には主に二通り挙げられる。一方は、磁気抵抗効果膜にかかっている電圧値の大きさを検出しその大きさによって情報を識別する方法であり、これを絶対検出という。他方は磁気抵抗効果膜の読み出し層の磁化方向のみ変化させ、そのときに生じる電圧の変化の違いによって情報を識別する方法である。読み出し層の磁化を反転させたとき、電圧値が例えば下がりこれを『1』とするならば、逆に電圧値が上がった場合は『0』である。このような読み出し方法を相対検出という。
【0057】
図10に1つの素子の周辺部分を模式的に示す断面図を示す。p型Si基板011に2つのn型拡散領域119および120を形成し、その間に絶縁層123を介してワード線(ゲート電極)342を形成する。n型拡散領域013に接地線356を接続し、他方にコンタクトプラグ352、353、354、357とローカル配線358を介して磁気抵抗効果膜105を接続する。磁気抵抗効果膜はさらにビット線332に接続されている。磁気抵抗効果膜105の横には磁界を発生させるための導線322および導線323が配されている。
【0058】
(比較例)
図11は従来の磁気抵抗効果膜を模式的に示した断面図である。基板001としてSiウエハーを用い、この表面を酸化処理し約1μmのSiO2膜002が形成されている。SiO2膜002上部に比較的磁化反転磁界の小さな磁性膜21として垂直磁化膜である30nmの膜厚のGd20Fe80膜、非磁性膜22として2nmの膜厚のAl2O3膜、比較的保磁力の大きな磁性膜23として垂直磁化膜である10nmのTb22Fe78膜、保護膜118として5nmのPt膜を順次形成した。ここで、Pt膜は磁性膜の酸化等の腐食を防ぐための保護膜である。Gd20Fe80膜およびTb22Fe78膜はどちらも遷移金属副格子磁化優勢である。次に得られた多層膜の上部に1μm角のレジスト膜を形成し、ドライエッチングによってレジストに覆われていない部分のPt膜およびTb22Fe78膜を除去した。エッチング後15nmの膜厚のAl2O3膜を成膜し、さらにレジストおよびその上部のAl2O3膜を除去し、上部電極とGd20Fe80膜からなる下部電極との短絡を防ぐための絶縁膜121を形成した。その後、リフトオフ法によって上部電極122をAl膜により作成し、上部電極からずれた位置のAl2O3膜を除去して測定回路を接続するための電極パットとした。さらに得られた磁気抵抗効果膜は膜面垂直方向に2MA/mの磁界を印加し、Tb22Fe78膜の磁化を印加磁界方向に向け着磁を行った。ただし、1cm角のTb22Fe78膜の保磁力は1.6MA/mと大きな値を示し、得られた磁気抵抗効果膜の保磁力も同程度の大きな値を示すと予想される。
【0059】
磁気抵抗効果膜の上部電極と下部電極に定電流電源を接続してGd20Fe80膜とTb22Fe78膜の間のAl2O3膜を電子がトンネルするように一定電流を流す。磁気抵抗効果膜の膜面に垂直方向に磁界を印加し、その大きさと方向を変えることにより磁気抵抗効果膜の電圧の変化(磁気抵抗曲線)を測定した。その結果を図12に示す。この測定結果によると磁化反転磁界は約24kA/mであった。
【0060】
【発明の効果】
上記の様に、本発明の磁気抵抗効果膜は、比較的小さな磁界で磁化反転可能であり、特にこの磁気抵抗効果膜を用いたメモリは消費電力を少なくすることが可能であるという効果がある。
【図面の簡単な説明】
【図1】本発明の磁気磁気抵抗効果膜の一例を示す断面を模式的に示した図である。
【図2】本発明の磁気磁気抵抗効果膜の一例を示す断面を模式的に示した図。
【図3】本発明の磁気磁気抵抗効果膜の一例を示す断面を模式的に示した図である。
【図4】実施例−1で用いた磁気抵抗効果膜の断面を模式的に示した図である。
【図5】実施例−1で用いた磁気抵抗効果膜の磁気抵抗曲線を示した図である。
【図6】実施例−2で用いた磁気抵抗効果膜の断面を模式的に示した図である。
【図7】実施例−2で用いた磁気抵抗効果膜の磁気抵抗曲線を示した図である。
【図8】実施例−3のメモリに用いた磁気抵抗効果膜に磁界を印加するための電気回路の概略図である。
【図9】実施例−3のメモリに用いた読み出し回路の概略図である。
【図10】実施例−3のメモリの一部分の断面を示した模式図である。
【図11】比較例で用いた磁気抵抗効果膜の断面を示した模式図である。
【図12】比較例で用いた磁気抵抗効果膜の磁気抵抗曲線を示した図である。
【図13】(a)磁気抵抗効果膜の磁化が平行な状態を模式的に示す断面図である。
(b)磁抵抗効果膜の磁化が反平行な状態を模式的に示す断面図である。
【図14】面内磁化膜を用いた従来の磁気抵抗効果膜における記録再生原理を説明するための図である。
(a)記録情報「1」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
(b)記録情報「0」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
(c)記録情報「1」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
(d)記録情報「0」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
【図15】垂直磁化膜を用いた従来の磁気抵抗効果膜における記録再生原理を説明するための図である。
(a)記録情報「1」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
(b)記録情報「0」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
(c)記録情報「1」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
(d)記録情報「0」の読み出しを行う場合の磁化の状態を模式的に示す断面図である。
【符号の説明】
001 Si基板
002 SiO2
011 p型Si基板
12、22 非磁性層
13、14、21、23 磁性層
100 固定抵抗
101〜109 磁気抵抗効果膜
111 第一の磁性膜
112 第二の磁性膜
113 非磁性膜
114 第三の磁性膜
116、117 スピン分極率の大きな材料からなる磁性膜
118 保護膜
119、120 n型拡散領域
121、123 絶縁膜
122 上部電極
211〜226、231〜242 トランジスタ
311〜314、321〜324 導線(書き込み線)
331〜333 ビット線
341〜343 ワード線(ゲート電極)
351〜355、357 コンタクトプラグ
356 接地線
357 ローカル配線
411、412 電源
500 センスアンプ
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetoresistive effect film using a method for reducing a magnetization reversal magnetic field of a perpendicular magnetization film, a memory element including the same, and a memory using the same.
[0002]
[Prior art]
In recent years, semiconductor memories, which are solid-state memories, are widely used in information equipment, and there are various types such as DRAM, FeRAM, and flash EEPROM. These semiconductor memories have advantages and disadvantages, and there is no memory that satisfies all of the specifications required for current information equipment. For example, DRAM has a high recording density and a large number of rewritable times, but it is volatile and information is lost when the power is turned off. In addition, the flash EEPROM is non-volatile, but the erasure time is long and is not suitable for high-speed information processing.
[0003]
In contrast to the current state of the semiconductor memory as described above, the memory (MRAM) using the magnetoresistive effect has specifications required by many information devices in terms of recording time, reading time, recording density, number of rewritable times, power consumption, etc. It is promising as a memory that fills everything. In particular, MRAM using the spin-dependent tunneling magnetoresistance (TMR) effect is advantageous for high recording density or high-speed reading because a large read signal can be obtained, and recent research reports have demonstrated its feasibility as MRAM. ing.
[0004]
The basic configuration of a magnetoresistive film used as an MRAM element is a sandwich structure in which a magnetic layer is formed adjacent to a nonmagnetic layer. Cu and Al are commonly used as nonmagnetic films.2OThreeIs mentioned. A magnetoresistive film that uses a conductor such as Cu as the nonmagnetic layer is called a giant magnetoresistive film (GMR film).2OThreeThose using insulators such as are called spin-dependent tunnel magnetoresistive films (TMR films). In general, a TMR film shows a larger magnetoresistance effect than a GMR film.
[0005]
When the magnetization directions of the two magnetic layers are parallel as shown in FIG. 13 (a), the electric resistance of the magnetoresistive film is relatively small, and when the magnetization directions are antiparallel as shown in FIG. 13 (b). The electrical resistance is relatively large. Therefore, information can be read by using one of the magnetic layers as a recording layer and the other as a reading layer and utilizing the above properties. For example, the magnetic layer 13 located above the nonmagnetic layer 12 is a recording layer, the magnetic layer 14 located below is a readout layer, and the magnetization direction of the recording layer is rightward, `` 1 '', and the leftward direction is `` 0 '' And When the magnetization directions of both magnetic layers are rightward as shown in FIG. 14A, the electric resistance of the magnetoresistive film is relatively small, and as shown in FIG. 14B, the magnetization direction of the readout layer is rightward and When the magnetization direction of the recording layer is leftward, the electric resistance is relatively large. In addition, when the magnetization direction of the reading layer is leftward and the magnetization direction of the recording layer is rightward as shown in FIG. 14C, the electric resistance is relatively large, and as shown in FIG. When the magnetization direction is leftward, the electrical resistance is relatively small. That is, when the magnetization direction of the readout layer is fixed to the right, if the electrical resistance is large, “0” is recorded in the recording layer, and if the electrical resistance is small, “1” is recorded. Will be. Alternatively, when the magnetization direction of the readout layer is fixed to the left, if the electrical resistance is large, “1” is recorded in the recording layer, and if the electrical resistance is small, “0” is recorded. Will be.
[0006]
If the element size is reduced in order to increase the recording density of the MRAM, the MRAM using the in-plane magnetization film has a problem that information cannot be retained due to the effect of demagnetizing field or end surface magnetization curling. In order to avoid this problem, for example, the shape of the magnetic layer can be rectangular. However, since the element size cannot be reduced by this method, the recording density is not expected to be improved much. Therefore, for example, as described in Japanese Patent Laid-Open No. 11-213650, a proposal has been made to avoid the above problem by using a perpendicular magnetization film. In this method, the demagnetizing field does not increase even when the element size is reduced. Therefore, a magnetoresistive film having a size smaller than that of the MRAM using the in-plane magnetization film can be realized.
[0007]
A magnetoresistive film using a perpendicular magnetized film, like a magnetoresistive film using an in-plane magnetized film, has a relatively small electrical resistance if the magnetization directions of the two magnetic layers are parallel. If the magnetization direction is antiparallel, the electrical resistance becomes relatively large. The magnetic layer 23 located above the nonmagnetic layer 22 is the recording layer, and the magnetic layer 21 located below is the readout layer.When the magnetization direction of the recording layer is upward, it is `` 1 '', and when it is downward, it is `` 0 '' To do. When the magnetization directions of both magnetic layers are upward as shown in FIG. 15A, the electric resistance of the magnetoresistive film is relatively small, and the magnetization direction of the readout layer is downward as shown in FIG. When the magnetization direction of the recording layer is upward, the electric resistance is relatively large. Therefore, if a magnetic field is applied so that the magnetization direction of the readout layer is downward after a magnetic layer is applied so that the magnetization direction of the readout layer is upward with “1” recorded, the magnetoresistive film The electrical resistance changes so as to increase, and “1” can be read from this change. However, the magnetic field applied at the time of reading is such a magnitude that the magnetization direction of the recording layer does not change. Further, when the magnetization direction of the reading layer is upward and the magnetization direction of the recording layer is downward as shown in FIG. 15B, the electric resistance becomes relatively large, and both magnetic layers are shown as shown in FIG. 15D. When the magnetization direction is downward, the electrical resistance is relatively small. Therefore, when “0” is recorded, it is possible to read “0” because the electrical resistance changes so as to decrease when the reading operation is performed.
[0008]
[Problems to be solved by the invention]
As the perpendicular magnetization film, an alloy film or artificial lattice film of at least one element selected from rare earth metals such as Gd, Dy, Tb and at least one element selected from transition metals such as Co, Fe, Ni, Co Main examples include artificial lattice films of transition metals such as / Pt and noble metals, and alloy films having crystal magnetic anisotropy in the direction perpendicular to the film surface, such as CoCr. The magnetization reversal field of the perpendicular magnetization film is generally larger than that having in-plane magnetic anisotropy due to transition metals, for example, the magnetization reversal field of permalloy, which is an in-plane magnetization film, is about several hundred A / m. The Co / Pt artificial lattice film, which is a perpendicular magnetization film, is remarkably large at several tens of kA / m. In an alloy film of a rare earth metal and a transition metal, since the sublattice magnetization of the rare earth metal and the sublattice magnetization of the transition metal are antiparallel, the apparent magnetization differs depending on the film composition. Therefore, the magnetization reversal field varies depending on the composition. The GdFe alloy film has a relatively small magnetization reversal field among the rare earth metal and transition metal alloy films, but the magnetization reversal is usually about several thousand A / m near the critical composition where the squareness ratio of the magnetization curve starts to decrease from 1. Has a magnetic field.
[0009]
When a sensor, memory, or the like is configured with a magnetoresistive film using a perpendicular magnetization film, it does not operate unless a large magnetic field is applied for the above reason. Therefore, for example, in the sensor, the stray magnetic field needs to be concentrated on the magnetic layer of the magnetoresistive effect film, and in the memory, a device for generating a large magnetic field is required. The magnetic field applied to the memory is generally generated by passing a current through the conducting wire, but in the case of a memory used for a portable terminal in particular, it is not preferable to flow a large current because of power supply capacity limitations. For this reason, it is necessary to take measures such as winding a conductive wire for generating a magnetic field around a memory element made of a magnetoresistive film. However, such a countermeasure complicates the structure and electric circuit around the magnetoresistive film, making it difficult to produce, and causes a problem of a decrease in yield and a significant increase in cost.
[0010]
In view of this point, the present invention provides a magnetoresistive film that reduces the magnetization reversal field of the perpendicular magnetization film, is easy to produce, and does not cause a decrease in yield or a significant increase in cost. The purpose is to provide less memory.
[0011]
[Means for Solving the Problems]
The magnetoresistive film of the present invention is
In a magnetoresistive film having a structure in which a nonmagnetic film is sandwiched between magnetic films, at least one of the magnetic films is a perpendicular magnetization film, and is in a position in contact with the perpendicular magnetization film and not in contact with the nonmagnetic film. And a magnetic film having an easy axis of magnetization inclined from the direction perpendicular to the film surface.
[0012]
Further, at least one easy axis of magnetization of the magnetic film may be inclined from the direction perpendicular to the film surface.
[0013]
Moreover, the magnetic film and the magnetic film whose easy axis of magnetization is inclined from the direction perpendicular to the film surface may be exchange coupled.
Furthermore, a layer having a higher spin polarizability than that of the perpendicular magnetization film may be inserted between the perpendicular magnetization film and the nonmagnetic film.
[0014]
Further, the perpendicular magnetization film and the layer having a high spin polarizability may be exchange coupled.
[0015]
In addition, the first magnetic film, the second magnetic film, the nonmagnetic film, the third magnetic film, and the easy magnetization axis are inclined from the film surface perpendicular direction. A fourth magnetic film is formed in this order, and at least one of the second magnetic film and the third magnetic film is a perpendicular magnetization film, the first magnetic film and the second magnetic film, and The third magnetic film and the fourth magnetic film may be exchange coupled.
[0016]
In addition, the easy magnetization axis of at least one of the second magnetic film or the third magnetic film may be inclined from the direction perpendicular to the film surface.
[0017]
A layer having a higher spin polarizability than that of the second magnetic film may be formed between the second magnetic film and the nonmagnetic film.
[0018]
Furthermore, a layer having a higher spin polarizability than that of the third magnetic film may be formed between the third magnetic film and the nonmagnetic film.
[0019]
The layer having a high spin polarizability and the second magnetic film, and the layer having a high spin polarizability and the third magnetic film may be exchange-coupled.
[0020]
In addition, the layer having a high spin polarizability may have a grain shape.
[0021]
Further, the magnetization of the magnetic film in which the easy axis of magnetization is inclined from the direction perpendicular to the film surface may be directed in the direction perpendicular to the film surface by a magnetic field having a magnitude of 4 kA / m or less.
[0022]
In addition, the magnetization of the magnetic film whose easy axis is oriented in the direction tilted from the direction perpendicular to the film surface is at least partially inclined with respect to the direction perpendicular to the film surface in the state of exchange coupling with the perpendicular magnetization film. Also good.
[0023]
The perpendicular magnetization film may be a ferrimagnetic material.
[0024]
The ferrimagnetic material may be an alloy of a rare earth metal and a transition metal.
[0025]
The alloy of rare earth metal and transition metal may be amorphous.
[0026]
Further, the ferrimagnetic material may be an artificial lattice film of a rare earth metal and a transition metal.
[0027]
The rare earth metal is one or more elements selected from Gd, Tb, and Dy, and transition gold
The genus may be one or more elements selected from Fe, Co, and Ni.
[0028]
The nonmagnetic film may be an insulator.
[0029]
The memory element of the present invention is
The memory element including the magnetoresistive film described above includes means for applying a magnetic field in the direction perpendicular to the film surface of the magnetoresistive film and means for detecting the electrical resistance of the magnetoresistive film.
[0030]
Further, the means for applying the magnetic field may be a conducting wire.
[0031]
Furthermore, a means for applying a magnetic field in a direction inclined from the direction perpendicular to the film surface of the magnetoresistive film may be provided.
[0032]
The memory of the present invention
In a memory using the above-described magnetoresistive film as a memory element, it is provided in contact with a magnetic film whose easy axis is inclined from the direction perpendicular to the film surface among magnetic films sandwiching a non-magnetic film when recording information. Information is recorded and reproduced without changing the magnetization direction of the magnetic film, and changing the magnetization direction of the other magnetic film.
[0033]
Of the magnetic films formed in contact with the non-magnetic film, the magnetic film whose magnetization is oriented in the direction perpendicular to the film surface in a zero magnetic field is used as the recording layer, and the magnetic film whose magnetization is inclined from the direction perpendicular to the film surface May be used as a readout layer.
[0034]
In addition, among the magnetic films formed adjacent to the nonmagnetic film against the magnetic field applied during recording or reading, the magnetization of the magnetic film formed in contact with one film surface of the nonmagnetic film is The magnetization of the magnetic film formed in contact with the other film surface of the nonmagnetic film may be reversed without being reversed.
[0035]
Further, a plurality of magnetoresistive effect films may be arranged, a means for selectively recording on the desired magnetoresistive effect film, and a means for selectively reading information recorded on the desired magnetoresistive effect film.
[0036]
Therefore, the magnetoresistive film of the present invention can be reversed in magnetization with a relatively small magnetic field. In particular, a memory using this magnetoresistive film can reduce power consumption.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
An example of the magnetoresistive film of the present invention is shown in FIG. A magnetic film in which the magnetization is oriented in a direction inclined from the perpendicular direction of the film surface in the absence of a magnetic field and no exchange force with another magnetic substance, i.e., the magnetization easy axis is inclined from the perpendicular direction of the film surface. One magnetic film 111, a second magnetic film 112 that is a perpendicular magnetization film, a nonmagnetic film 113, and a third magnetic film 114 that is a perpendicular magnetization film are sequentially formed. The first magnetic film 111 and the second magnetic film 112 are exchange coupled. The magnetization of the second magnetic film 112 is oriented in the direction perpendicular to the film surface at least near the interface with the nonmagnetic film 113 in a zero magnetic field, or easily applied in the direction perpendicular to the film surface when a magnetic field is applied in the direction perpendicular to the film surface. Keep it facing. In the MRAM, it is preferable that the magnitude of the magnetic field that can be applied to the memory element is 4 kA / m or less because of the limitation of the current density that flows in the conducting wire. Therefore, the magnetization tilted from the vertical direction of the film surface in the zero magnetic field should be oriented in the vertical direction by applying a magnetic field of 4 kA / m or less. When a magnetic film whose magnetization is directed from the direction perpendicular to the film surface is exchange-coupled to the perpendicular magnetization film in the absence of a magnetic field and in the state where no exchange force with another magnetic material is working, the perpendicular magnetization film is Perpendicular magnetic anisotropy apparently decreases. Therefore, the magnetization reversal magnetic field in the direction perpendicular to the film surface can be reduced.
[0038]
A magnetoresistive film using an exchange coupling film of a perpendicular magnetization film and an in-plane magnetization film is disclosed in Japanese Patent Laid-Open No. 2000-306374. The main difference between the present invention and the present invention is the position where a magnetic film whose magnetization is oriented in a direction inclined from the direction perpendicular to the film surface is disposed. In Japanese Patent Laid-Open No. 2000-306374, the purpose is to obtain a large magnetoresistance effect, and a means is to form a magnetic film having a large spin polarizability so as to be in contact with the nonmagnetic film. An in-plane magnetization film is used for a magnetic film having a large spin polarizability, but the magnetization of the magnetic film must be oriented in the direction perpendicular to the film surface. Is achieved by the exchange coupling force.
[0039]
On the other hand, the present invention aims to reduce the magnetization reversal magnetic field with respect to the magnetic field applied in the direction perpendicular to the film surface. Magnetization is performed in the absence of a magnetic field and in the absence of exchange force with other magnetic materials. The magnetic film oriented in the direction inclined from the direction perpendicular to the film surface is not in contact with the nonmagnetic film, and the magnetization of the magnetic film need not be oriented in the direction perpendicular to the film surface.
[0040]
Even if a magnetic film with a magnetization oriented in a direction inclined from the direction perpendicular to the film surface in the absence of a magnetic field and no exchange force with another magnetic material is formed so as to contact the non-magnetic film, it will not contact However, the magnetization reversal field of the exchange coupling film between the magnetic film and the perpendicular magnetization film is smaller than that in the case of the perpendicular magnetization film single layer. However, the magnetization reversal in the direction perpendicular to the film surface depends on the thickness of the magnetic film whose magnetization is directed in the direction inclined from the direction perpendicular to the film surface, and the film thickness of the magnetic film is determined by the magnitude of the magnetization reversal magnetic field. It is done. In Japanese Patent Laid-Open No. 2000-306374, as described above, since the magnetization needs to be directed in the direction perpendicular to the film surface, the in-plane magnetization film cannot be increased in thickness, and the in-plane magnetization film has a thickness of 2 nm. Since it is necessary to make the following, the amount of decrease in the magnetization reversal magnetic field cannot be expected so much. On the other hand, in the magnetoresistive film of the present invention, it is not necessary to direct the magnetization of the magnetic film whose magnetization is inclined from the direction perpendicular to the film surface in the direction perpendicular to the film surface. It is possible to make it relatively thick, and for this reason, it is easy to sufficiently reduce the magnetization switching magnetic field in the direction perpendicular to the film surface.
[0041]
As described above, the film configuration shown in FIG. 1 can be cited as an example of the embodiment of the present invention. In the state of exchange coupling with the second magnetic film 112, the magnetization of the first magnetic film 111 may be oriented in the direction perpendicular to the film surface or may be inclined from the direction perpendicular to the film surface. However, when a magnetoresistive film whose magnetization is inclined from the direction perpendicular to the film surface is used as a memory element, it is necessary that both the magnetization of the third magnetic film 114 and the magnetization of the second magnetic film 112 can be reversed. The third magnetic film 114 is a recording layer, and the second magnetic film 112 is a reading layer. When a current is passed through a conducting wire and recording is performed with a magnetic field generated by this current, it is generally difficult to generate a magnetic field larger than 4 kA / m. Therefore, recording on the third magnetic film 114 is 4 kA / m. The following magnetic field is preferably used, and at the time of reading, the magnetization of the second magnetic film 112 inclined from the direction perpendicular to the film surface is caused by a magnetic field smaller than the reversal magnetic field of the third magnetic film 114. It is preferable to face in the direction perpendicular to the film surface. Further, the magnetization of the second magnetic film 112 is reversed by a magnetic field smaller than the magnetization of the third magnetic film 114.
[0042]
As the perpendicular magnetization film, as described above, an alloy film of at least one element selected from rare earth metals such as Gd, Dy, and Tb and at least one element selected from transition metals such as Co, Fe, and Ni, or an artificial film is used. Lattice films, artificial lattice films of transition metals and noble metals such as Co / Pt, and alloy films having crystal magnetic anisotropy in the direction perpendicular to the film surface, such as CoCr, can be mainly used. As a magnetic film in which the magnetization is directed in a direction tilted from the direction perpendicular to the film surface in a non-magnetic field and in a state in which no exchange force with other magnetic materials is acting, the magnetic film having the perpendicular magnetic anisotropy described above is used. Using similar materials, Ku-2πMs2It can be obtained by adjusting the film forming conditions so that <0. This makes it possible to obtain a magnetic film whose easy axis is inclined from the direction perpendicular to the film surface. Here, Ku is the perpendicular magnetic anisotropy energy constant, and Ms is the saturation magnetization. An in-plane magnetization film using a film made of one kind of element selected from transition metals such as Co, Fe, Ni, or an alloy film made of two or more kinds of elements can also be used.
[0043]
As the nonmagnetic film 113, a conductor such as Cu or Cr or Al2OThreeInsulators such as NiO can be used. When an insulator is used for the nonmagnetic film 113, a relatively large change in magnetoresistance can be obtained, which is preferable when used as a memory element.
[0044]
When the magnetoresistive film having the film configuration shown in FIG. 1 is used as a memory element, the magnetization of the second magnetic film 112 can be reversed by an applied magnetic field, and the magnetization of the third magnetic film 114 can be reversed. Either is possible or not. However, when the magnetization of the third magnetic film 114 cannot be reversed, the voltage of the element is directly read without changing the magnetization direction so as not to destroy the recorded information at the time of reading. Is preferred. When the magnetization of the third magnetic film 114 is reversible, the exchange coupling film of the first magnetic film 111 and the second magnetic film 112 having a relatively small magnetization reversal magnetic field is used as a readout layer, and the magnetization is relatively The third magnetic film 114 having a large reversal magnetic field can be used as the recording layer, and information recorded by reading the voltage change of the element caused by reversing the magnetization direction of the second magnetic film 112 is recorded. Can be read nondestructively.
[0045]
FIG. 2 is a cross-sectional view schematically showing a film configuration as an example of the embodiment of the present invention, which is different from the film configuration shown in FIG. 1 in that a fourth magnetic film 115 is formed. The fourth magnetic film 115 is a magnetic film in which the magnetization is directed in a direction inclined from the direction perpendicular to the film surface in a state where there is no magnetic field and no exchange force with another magnetic material is applied. Exchange coupled with membrane 114. That is, like the first magnetic film 111, it functions to reduce the magnetization reversal field of the perpendicular magnetization film. With such a configuration, both the second magnetic film 112 and the third magnetic film 114 can be reversed in magnetization with a small applied magnetic field. However, the magnitude of the magnetization reversal field of the second magnetic film 112 and the magnetization reversal field of the third magnetic film 114 are different. When the magnetoresistive film having such a configuration is used as a memory, the exchange coupling film of the first magnetic film 111 and the second magnetic film 112 and the exchange coupling film of the third magnetic film 114 and the fourth magnetic film 115 are used. Of these, the relatively small magnetization reversal field is the readout layer, and the relatively large magnetization reversal field is the recording layer. The magnitude of the magnetization reversal field can be adjusted by the composition, film thickness, film forming conditions, etc. of each magnetic film.
[0046]
Further, as shown in FIG. 3, it is possible to increase the magnetic resistance by forming magnetic films 116 and 117 made of a material having a high spin polarizability at the interface between the nonmagnetic film 113 and the magnetic film. In FIG. 3, such a film is formed on both interfaces, but only one of them may be formed. The magnetic films 116 and 117 formed at the interface may be either the one whose magnetization is oriented in the direction inclined from the film surface perpendicular direction or the perpendicular magnetization film, but the second magnetic film 112 and the third magnetic film, respectively. In the state of exchange coupling with 114, the magnetization in the vicinity of the interface with the nonmagnetic film 113 needs to be perpendicular to the film surface.
[0047]
Further, the magnetic film 116 and the magnetic film 117 may have a grain shape.
[0048]
In the above magnetoresistive film of the present invention, the nonmagnetic film may be a metal such as Cu or Al.2OThreeHowever, when using it as a memory, it is preferable to use a nonmagnetic film as a dielectric because the change in magnetoresistance is large.
[0049]
A plurality of magnetoresistive films having any of the above film structures are arranged side by side, and a relatively large magnetic field is applied to only one desired element, whereby a memory cell capable of selective recording can be obtained. it can.
[0050]
【Example】
(Example-1)
FIG. 4 is a cross-sectional view schematically showing a magnetoresistive film of the present invention. Using a Si wafer as the substrate 001, this surface was oxidized and about 1 μm SiO2A film 002 is formed. SiO2On the top of the film 002, the first magnetic film 111 is an in-plane magnetic film of 5 nm thick Fe film, and the second magnetic film 112 is a perpendicular magnetic film of 30 nm thick Gd.20Fe802nm thick Al film as non-magnetic film 1132OThree10nm Tb which is a perpendicular magnetized film as the third magnetic film 114twenty twoFe78A 5 nm Pt film was sequentially formed as a film and a protective film 118. Where Fe film and Gd20Fe80The film is exchange-coupled, and the Pt film is a protective film for preventing corrosion such as oxidation of the magnetic film. Gd20Fe80Membrane and Tbtwenty twoFe78Both films are transition metal sublattice magnetization dominant. Next, a 1 μm square resist film is formed on top of the obtained multilayer film, and the Pt film and Tb of the part not covered with the resist by dry etchingtwenty twoFe78The membrane was removed. 15nm thickness Al after etching2OThreeA film is formed, and the resist and Al2OThreeRemove the film, upper electrode and Fe film and Gd20Fe80An insulating film 121 for preventing a short circuit with the lower electrode made of the film was formed. After that, the upper electrode 122 is made of an Al film by a lift-off method, and the Al at a position shifted from the upper electrode is formed.2OThreeAn electrode pad for removing the film and connecting the measurement circuit was obtained. Further, the obtained magnetoresistive film applied a magnetic field of 2 MA / m in the direction perpendicular to the film surface, and Tbtwenty twoFe78Magnetization was performed with the magnetization of the film directed in the direction of the applied magnetic field. However, 1cm square Tbtwenty twoFe78The coercive force of the film is as large as 1.6 MA / m, and the coercive force of the obtained magnetoresistive film is expected to be as large as the same.
[0051]
Connect a constant current power supply to the upper and lower electrodes of the magnetoresistive effect film20Fe80Membrane and Tbtwenty twoFe78Al between membranes2OThreeA constant current is passed so that electrons tunnel through the film. A magnetic field was applied in the direction perpendicular to the film surface of the magnetoresistive effect film, and the change (magnetoresistive curve) of the voltage of the magnetoresistive effect film was measured by changing the magnitude and direction. The result is shown in FIG. According to this measurement result, the magnetization reversal was about 3 kA / m.
[0052]
(Example-2)
FIG. 6 is a cross-sectional view schematically showing the magnetoresistive film of the present invention. Using a Si wafer as the substrate 001, this surface was oxidized and about 1 μm SiO2A film 002 is formed. SiO2On the top of the film 002, the first magnetic film 111 is an in-plane magnetic film of 3 nm thick Fe film, and the second magnetic film 112 is a perpendicular magnetic film of 50 nm thick Gd.twenty fiveFe75As a fifth magnetic film 116 having a larger spin polarizability than the second magnetic film, a Co film having a thickness of 1 nm is an in-plane magnetization film.50Fe502nm thick Al film as non-magnetic film 1132OThreeAs a sixth magnetic film 117 exhibiting a larger spin polarizability than that of the third magnetic film, a Co film having a thickness of 1 nm is an in-plane magnetization film.50Fe50Tb with a thickness of 30 nm which is a perpendicular magnetization film as the third magnetic film 114twenty fiveFe75A 3 nm thick Fe film, which is an in-plane magnetized film, was formed as the fourth magnetic film 115, and a 5 nm Pt film was sequentially formed as the protective film 118. Where Fe film and Gdtwenty fiveFe75Membrane, Gdtwenty fiveFe75Membrane and Co50Fe50Each membrane is exchange-coupled and Co50Fe50Membrane and Tbtwenty fiveFe75Membrane, Tbtwenty fiveFe75The film and the Fe film are exchange coupled. Gdtwenty fiveFe75Membrane and Tbtwenty fiveFe75Both films are rare earth metal sublattice magnetization dominant. 2 layers of Co50Fe50The film is Gdtwenty fiveFe75Membrane or Tbtwenty fiveFe75The spin polarizability is larger than that of the film, and the direction of magnetization is oriented in the direction perpendicular to the film surface due to the exchange coupling force. The Pt film is a protective film for preventing corrosion such as oxidation of the magnetic film. Next, a 1 μm square resist film is formed on top of the obtained multilayer film, and the Pt film and Tb of the part not covered with the resist by dry etchingtwenty fiveFe75The membrane was removed. 39nm thickness Al after etching2OThreeA film is formed, and the resist and Al2OThreeRemove the film, upper electrode and Fe film and Gdtwenty fiveFe75An insulating film 121 for preventing a short circuit with the lower electrode made of the film was formed. After that, the upper electrode 122 is made of an Al film by a lift-off method, and the Al at a position shifted from the upper electrode is formed.2OThreeAn electrode pad for removing the film and connecting the measurement circuit was obtained.
[0053]
Connect a constant current power supply to the upper and lower electrodes of the magnetoresistive effect filmtwenty fiveFe75Membrane and Tbtwenty fiveFe75Al between membranes2OThreeA constant current is passed so that electrons tunnel through the film. A change in voltage of the magnetoresistive effect film was measured by applying a magnetic field in a direction perpendicular to the film surface of the magnetoresistive effect film and changing its magnitude and direction. The result is shown in FIG. Magnetization reversal occurs at about 2.5 kA / m and 3.8 kA / m.
[0054]
(Example-3)
FIG. 8 is an electric circuit diagram of a memory cell when the magnetoresistive films 101, 102, 103, 104, 105, 106, 107, 108, 109 used in Example-2 are arranged in 3 rows and 3 columns as memory elements. And shown in FIG. FIG. 8 is a circuit for generating a magnetic field applied to the magnetoresistive effect film, and FIG. 9 is a circuit for detecting a resistance change of the magnetoresistive effect film.
[0055]
A method for selectively reversing the magnetization of the magnetic film of an arbitrary element will be described. For example, when the magnetization of the magnetoresistive film 105 is selectively reversed, the transistors 212, 217, 225, and 220 are turned on, and the other transistors are turned off. In this way, current flows through the conductors 312, 313, 323, 322 and generates a magnetic field around them. Therefore, if the magnetic field in the same direction is applied only from the four conducting wires to the magnetoresistive effect film 105 and these combined magnetic fields are adjusted so as to be slightly larger than the magnetization reversal field of the magnetic film of the element, it is possible to selectively Only the magnetization of the magnetoresistive film 105 can be reversed. When applying a magnetic field in the reverse direction to the magnetoresistive film 105, the transistors 213, 216, 224, and 221 are turned on, and the other transistors are turned off. In this way, the current flows in the direction opposite to the previous direction through the conducting wires 312, 313, 323, and 322, and a reverse magnetic field is applied to the magnetoresistive film 105.
[0056]
Next, the operation during reading will be described. For example, when information recorded on the magnetoresistive film 105 is read, the transistor 235 and the transistor 241 are turned on. Then, a circuit in which the power supply 412, the fixed resistor 100, and the magnetoresistive film 105 are connected in series is obtained. Therefore, the power supply voltage is divided into the respective resistors at the ratio of the resistance value of the fixed resistor 100 and the resistance value of the magnetoresistive effect film 105. Since the power supply voltage is fixed, when the resistance value of the magnetoresistive effect film changes, the voltage applied to the magnetoresistive effect film changes accordingly. This voltage value is read by the sense amplifier 500. Here, there are mainly two reading methods. One is a method of detecting the magnitude of the voltage value applied to the magnetoresistive effect film and identifying information based on the magnitude, and this is called absolute detection. The other is a method in which only the magnetization direction of the readout layer of the magnetoresistive film is changed, and information is identified by the difference in voltage change that occurs at that time. When the magnetization of the readout layer is reversed, if the voltage value drops, for example, to “1”, the voltage value rises to “0”. Such a reading method is called relative detection.
[0057]
FIG. 10 is a cross-sectional view schematically showing a peripheral portion of one element. Two n-type diffusion regions 119 and 120 are formed on a p-type Si substrate 011, and a word line (gate electrode) 342 is formed therebetween via an insulating layer 123. A ground line 356 is connected to the n-type diffusion region 013, and the magnetoresistive effect film 105 is connected to the other via contact plugs 352, 353, 354, 357 and local wiring 358. The magnetoresistive film is further connected to the bit line 332. Next to the magnetoresistive effect film 105, a conducting wire 322 and a conducting wire 323 for generating a magnetic field are arranged.
[0058]
(Comparative example)
FIG. 11 is a cross-sectional view schematically showing a conventional magnetoresistive film. Using a Si wafer as the substrate 001, this surface was oxidized and about 1 μm SiO2A film 002 is formed. SiO2Gd with a thickness of 30 nm is a perpendicular magnetization film as a magnetic film 21 having a relatively small magnetization reversal magnetic field on the film 00220Fe802nm thick Al film as non-magnetic film 222OThree10 nm Tb which is a perpendicular magnetization film as a magnetic film 23 having a relatively large coercive forcetwenty twoFe78A 5 nm Pt film was sequentially formed as a film and a protective film 118. Here, the Pt film is a protective film for preventing corrosion such as oxidation of the magnetic film. Gd20Fe80Membrane and Tbtwenty twoFe78Both films are transition metal sublattice magnetization dominant. Next, a 1 μm square resist film is formed on top of the obtained multilayer film, and the Pt film and Tb of the part not covered with the resist by dry etchingtwenty twoFe78The membrane was removed. 15nm thickness Al after etching2OThreeA film is formed, and the resist and Al2OThreeRemove the membrane, top electrode and Gd20Fe80An insulating film 121 for preventing a short circuit with the lower electrode made of the film was formed. After that, the upper electrode 122 is made of an Al film by a lift-off method, and the Al at a position shifted from the upper electrode is formed.2OThreeAn electrode pad for removing the film and connecting the measurement circuit was obtained. Further, the obtained magnetoresistive film applied a magnetic field of 2 MA / m in the direction perpendicular to the film surface, and Tbtwenty twoFe78Magnetization was performed with the magnetization of the film directed in the direction of the applied magnetic field. However, 1cm square Tbtwenty twoFe78The coercive force of the film is as large as 1.6 MA / m, and the coercive force of the obtained magnetoresistive film is expected to be as large as the same.
[0059]
Connect a constant current power supply to the upper and lower electrodes of the magnetoresistive effect film20Fe80Membrane and Tbtwenty twoFe78Al between membranes2OThreeA constant current is passed so that electrons tunnel through the film. A magnetic field was applied in the direction perpendicular to the film surface of the magnetoresistive effect film, and the change (magnetoresistive curve) of the voltage of the magnetoresistive effect film was measured by changing the magnitude and direction. The result is shown in FIG. According to this measurement result, the magnetization reversal field was about 24 kA / m.
[0060]
【The invention's effect】
As described above, the magnetoresistive film of the present invention can be reversed in magnetization with a relatively small magnetic field, and in particular, a memory using this magnetoresistive film has an effect that power consumption can be reduced. .
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a cross section showing an example of a magneto-resistive film of the present invention.
FIG. 2 is a diagram schematically showing a cross section showing an example of a magneto-resistive film of the present invention.
FIG. 3 is a view schematically showing a cross section showing an example of a magneto-resistive film of the present invention.
FIG. 4 is a diagram schematically showing a cross section of a magnetoresistive film used in Example-1.
FIG. 5 is a diagram showing a magnetoresistance curve of a magnetoresistive film used in Example-1.
6 is a view schematically showing a cross section of a magnetoresistive film used in Example-2. FIG.
7 is a diagram showing a magnetoresistance curve of a magnetoresistive film used in Example-2. FIG.
8 is a schematic diagram of an electric circuit for applying a magnetic field to the magnetoresistive film used in the memory of Example-3. FIG.
FIG. 9 is a schematic diagram of a read circuit used in the memory of Example-3.
FIG. 10 is a schematic diagram showing a cross section of a part of the memory of Example-3;
FIG. 11 is a schematic diagram showing a cross section of a magnetoresistive film used in a comparative example.
FIG. 12 is a diagram showing a magnetoresistance curve of a magnetoresistive film used in a comparative example.
FIG. 13A is a cross-sectional view schematically showing a state in which the magnetization of the magnetoresistive effect film is parallel.
(B) It is sectional drawing which shows typically the state by which the magnetization of a magnetoresistive effect film is antiparallel.
FIG. 14 is a diagram for explaining the principle of recording / reproducing in a conventional magnetoresistive film using an in-plane magnetization film.
(A) It is sectional drawing which shows typically the state of the magnetization in the case of reading the recording information "1".
(B) It is sectional drawing which shows typically the state of the magnetization in the case of reading recording information "0".
(C) It is sectional drawing which shows typically the state of the magnetization in the case of reading recording information "1".
(D) It is sectional drawing which shows typically the state of the magnetization in the case of reading recording information "0".
FIG. 15 is a diagram for explaining the principle of recording / reproducing in a conventional magnetoresistive film using a perpendicular magnetization film.
(A) It is sectional drawing which shows typically the state of the magnetization in the case of reading the recording information "1".
(B) It is sectional drawing which shows typically the state of the magnetization in the case of reading recording information "0".
(C) It is sectional drawing which shows typically the state of the magnetization in the case of reading recording information "1".
(D) It is sectional drawing which shows typically the state of the magnetization in the case of reading recording information "0".
[Explanation of symbols]
001 Si substrate
002 SiO2film
011 p-type Si substrate
12, 22 Nonmagnetic layer
13, 14, 21, 23 Magnetic layer
100 fixed resistance
101-109 magnetoresistive film
111 First magnetic film
112 Second magnetic film
113 Non-magnetic film
114 Third magnetic film
116, 117 Magnetic film made of material with high spin polarizability
118 Protective film
119, 120 n-type diffusion region
121, 123 Insulating film
122 Upper electrode
211 to 226, 231 to 242 transistors
311 to 314, 321 to 324 Conductor (write line)
331 to 333 bit line
341 to 343 Word line (gate electrode)
351 to 355, 357 Contact plug
356 Ground wire
357 Local wiring
411, 412 power supply
500 sense amplifiers

Claims (17)

非磁性膜が第一及び第二の磁性膜に挟まれている構造を持った磁気抵抗効果膜において、
前記第一及び第二の磁性膜が垂直磁化膜であり、前記第一の磁性膜に接して,且つ前記非磁性膜には接しない位置に、磁化容易軸が膜面垂直方向から傾いている磁性膜が配され、前記第一の磁性膜と交換結合をしており、前記第一磁性膜の磁化反転磁界は前記第二の磁性膜の磁化反転磁界よりも小さいことを特徴とする磁気抵抗効果膜。
In a magnetoresistive film having a structure in which a nonmagnetic film is sandwiched between first and second magnetic films,
The first and second magnetic films are perpendicular magnetization films, and the easy axis of magnetization is tilted from the direction perpendicular to the film surface at a position in contact with the first magnetic film and not in contact with the nonmagnetic film. A magnetoresistive film characterized in that a magnetic film is disposed and exchange-coupled with the first magnetic film, and the magnetization reversal field of the first magnetic film is smaller than the magnetization reversal field of the second magnetic film Effect film.
非磁性膜が第一及び第二の磁性膜に挟まれている構造を持った磁気抵抗効果膜において、
前記第一及び第二の磁性膜が垂直磁化膜であり、前記第一の磁性膜に接して,且つ前記非磁性膜には接しない位置に、磁化容易軸が膜面垂直方向から傾いている磁性膜が配され、前記第一の磁性膜と交換結合をしており、前記磁化容易軸が膜面垂直方向から傾いている磁性膜と交換結合している前記第一磁性膜の磁化反転磁界は前記第1磁性膜が単層で設けられた時と比べて小さいことを特徴とする磁気抵抗効果膜。
In a magnetoresistive film having a structure in which a nonmagnetic film is sandwiched between first and second magnetic films,
The first and second magnetic films are perpendicular magnetization films, and the easy axis of magnetization is tilted from the direction perpendicular to the film surface at a position in contact with the first magnetic film and not in contact with the nonmagnetic film. A magnetic reversal field of the first magnetic film in which a magnetic film is arranged and exchange-coupled to the first magnetic film, and the easy magnetization axis is exchange-coupled to a magnetic film inclined from the direction perpendicular to the film surface Is smaller than when the first magnetic film is provided as a single layer.
更に、前記垂直磁化膜と前記非磁性膜の間に前記垂直磁化膜よりもスピン分極率の大きな層が挿入されており、前記垂直磁化膜と前記スピン分極率の大きな層が交換結合していることを特徴とする請求項1または2に記載の磁気抵抗効果膜。Furthermore, a layer having a higher spin polarizability than that of the perpendicular magnetization film is inserted between the perpendicular magnetization film and the nonmagnetic film, and the perpendicular magnetization film and the layer having a higher spin polarization rate are exchange coupled. The magnetoresistive film according to claim 1 or 2. 磁化容易軸が膜面垂直方向から傾いている第一の磁性膜と、第二の磁性膜と、非磁性膜と、第三の磁性膜と、磁化容易軸が膜面垂直方向から傾いている第四の磁性膜とがこの順に形成され、
前記第二の磁性膜及び第三の磁性膜が垂直磁化膜であり、
前記第一の磁性膜と前記第二の磁性膜、および前記第三の磁性膜と前記第四の磁性膜がそれぞれ交換結合しており、
前記第一の磁性膜と交換結合した第二の磁性膜の磁化反転磁界は、前記第四の磁性膜と交換結合した第三の磁性膜の磁化反転磁界よりも大きいことを特徴とする磁気抵抗効果膜。
The first magnetic film, the second magnetic film, the nonmagnetic film, the third magnetic film, and the easy magnetization axis are inclined from the film surface perpendicular direction. A fourth magnetic film is formed in this order,
The second magnetic film and the third magnetic film are perpendicular magnetization films;
The first magnetic film and the second magnetic film, and the third magnetic film and the fourth magnetic film are exchange-coupled, respectively.
The magnetic reversal field of the second magnetic film exchange-coupled to the first magnetic film is larger than the magnetization reversal field of the third magnetic film exchange-coupled to the fourth magnetic film. Effect film.
前記第二の磁性膜と前記非磁性膜との間に前記第二の磁性膜よりもスピン分極率大きく前記第二の磁性膜と交換結合している層が形成されていることを特徴とする請求項に記載の磁気抵抗効果膜。Characterized in that said second layer magnetic film spin polarization than are exchange-coupled to the magnitude rather the second magnetic film is formed between the second magnetic film and the nonmagnetic film The magnetoresistive film according to claim 4 . 更に、前記第三の磁性膜と前記非磁性膜との間に前記第三の磁性膜よりもスピン分極率大きく前記第三の磁化膜と交換結合している層が形成されていることを特徴とする請求項に記載の磁気抵抗効果膜。Moreover, said third layer spin polarization than that of the magnetic film is exchange-coupled to the magnitude rather the third magnetic film is formed between said third magnetic film and the nonmagnetic film The magnetoresistive film according to claim 5 . 前記スピン分極率の大きな層が粒形状であることを特徴とする請求項3、5、6のいずれか1項に記載の磁気抵抗効果膜。The magnetoresistive film according to claim 3 , wherein the layer having a high spin polarizability has a grain shape. 前記磁化容易軸が膜面垂直方向から傾いている磁性膜の磁化が、4kA/m以下の大きさの磁界によって、膜面垂直方向に向くことを特徴とする請求項1、2またはに記載の磁気抵抗効果膜。Magnetization of the magnetic film in which the easy axis of magnetization is inclined from the direction perpendicular to the film surface is, by a magnetic field of 4 kA / m or less in size, according to claim 1, 2 or 4, wherein the facing in a direction perpendicular to the film surface Magnetoresistive film. 前記磁化容易軸が膜面垂直方向から傾いた方向に向いている磁性膜の磁化が、前記垂直磁化膜と交換結合している状態において、少なくとも部分的に膜面垂直方向に対して傾いていることを特徴とする請求項1からのいずれか1項に記載の磁気抵抗効果膜。The magnetization of the magnetic film in which the easy axis is oriented in a direction inclined from the direction perpendicular to the film surface is at least partially inclined with respect to the direction perpendicular to the film surface in the state of exchange coupling with the perpendicular magnetization film. The magnetoresistive film according to any one of claims 1 to 8 , wherein 前記非磁性膜が絶縁体であることを特徴とする請求項1からのいずれか1項に記載の磁気抵抗効果膜。It said non-magnetic film is the magnetoresistive film of any one of claims 1 to 9, characterized in that an insulator. 請求項1から10のいずれか1項に記載の磁気抵抗効果膜を備えたメモリ素子において、
前記磁気抵抗効果膜の膜面垂直方向に磁界を印加する手段と、
前記磁気抵抗効果膜の電気抵抗を検出する手段とを備えたことを特徴とするメモリ素子。
A memory device comprising the magnetoresistive film according to any one of claims 1 to 10 ,
Means for applying a magnetic field in a direction perpendicular to the film surface of the magnetoresistive film;
And a memory element for detecting an electric resistance of the magnetoresistive film.
前記磁界を印加する手段が導線であることを特徴とする請求項11に記載のメモリ素子。The memory element according to claim 11 , wherein the means for applying the magnetic field is a conductive wire. 更に、前記磁気抵抗効果膜の膜面垂直方向から傾いた方向に磁界を印加する手段を備えたことを特徴とする請求項11に記載のメモリ素子。12. The memory element according to claim 11 , further comprising means for applying a magnetic field in a direction inclined from a direction perpendicular to the film surface of the magnetoresistive film. 請求項1または2に記載の磁気抵抗効果膜をメモリ素子として用いたメモリにおいて、
情報の記録時に、非磁性膜を挟んでいる磁性膜のうち、磁化容易軸が膜面垂直方向から傾いている磁性膜と接して設けられている磁性膜の磁化方向を変化させ、他方の磁性膜の磁化方向は変化させずに情報の記録再生を行なうことを特徴とするメモリ。
In a memory using the magnetoresistive film according to claim 1 as a memory element,
When recording information, among the magnetic films sandwiching the non-magnetic film, the magnetization direction of the magnetic film provided in contact with the magnetic film whose easy axis is inclined from the direction perpendicular to the film surface is changed, and the other magnetic A memory which records and reproduces information without changing the magnetization direction of the film.
請求項1または2に記載の磁気抵抗効果膜をメモリ素子として用いたメモリにおいて、
非磁性膜に接して形成されている磁性膜のうち、零磁場中で磁化が膜面垂直方向に向いている磁性膜を記録層とし、磁化が膜面垂直方向から傾いている磁性膜を、前記記録層に記録された情報を読み出すための読み出し層とすることを特徴とするメモリ。
In a memory using the magnetoresistive film according to claim 1 as a memory element,
Among the magnetic films formed in contact with the non-magnetic film, a magnetic film whose magnetization is oriented in the direction perpendicular to the film surface in a zero magnetic field is used as a recording layer, and a magnetic film whose magnetization is inclined from the direction perpendicular to the film surface, A memory comprising a reading layer for reading information recorded on the recording layer.
請求項1から10のいずれか1項に記載の磁気抵抗効果膜をメモリ素子として用いたメモリにおいて、
記録あるいは読み出し時に印加される磁界に対して、非磁性膜に隣接して形成されている磁性膜のうち、非磁性膜の一方の膜面に接して形成されている磁性膜の磁化は反転することなく、非磁性膜の他方の膜面に接して形成されている磁性膜の磁化は反転することを特徴とするメモリ。
A memory using the magnetoresistive film according to any one of claims 1 to 10 as a memory element,
Of the magnetic film formed adjacent to the nonmagnetic film, the magnetization of the magnetic film formed in contact with one surface of the nonmagnetic film is reversed with respect to the magnetic field applied during recording or reading. A memory characterized in that the magnetization of the magnetic film formed in contact with the other film surface of the nonmagnetic film is reversed.
請求項1から10のいずれか1項に記載の磁気抵抗効果膜をメモリ素子として用いたメモリにおいて、
前記磁気抵抗効果膜を複数配列し、所望の磁気抵抗効果膜に選択的に記録する手段と、
所望の磁気抵抗効果膜に記録された情報を選択的に読み出す手段とを備えたことを特徴とするメモリ。
A memory using the magnetoresistive film according to any one of claims 1 to 10 as a memory element,
Means for arranging a plurality of magnetoresistive films and selectively recording on a desired magnetoresistive film;
A memory comprising: means for selectively reading information recorded on a desired magnetoresistive film.
JP2001245423A 2001-04-02 2001-08-13 Magnetoresistive film, memory element including the same, and memory using the same Expired - Fee Related JP4944315B2 (en)

Priority Applications (7)

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JP2001245423A JP4944315B2 (en) 2001-08-13 2001-08-13 Magnetoresistive film, memory element including the same, and memory using the same
TW091106511A TW560095B (en) 2001-04-02 2002-04-01 Magnetoresistive element, memory element having the magnetoresistive element, and memory using the memory element
DE60223440T DE60223440T2 (en) 2001-04-02 2002-04-02 Magnetoresistive element, memory element with such magnetoresistive element, and memory using such a memory element
KR10-2002-0017937A KR100498998B1 (en) 2001-04-02 2002-04-02 Magnetoresistive element, memory element having the magnetoresistive element, and memory using the memory element
CN021198284A CN1384503B (en) 2001-04-02 2002-04-02 Magnetic resistance element, memory unit with the element and memory constituted by the memory units
US10/113,983 US6829121B2 (en) 2001-04-02 2002-04-02 Magnetoresistive element, memory element having the magnetoresistive element, and memory using the memory element
EP02007503A EP1248264B1 (en) 2001-04-02 2002-04-02 Magnetoresistive element, memory element having the magnetoresistive element, and memory using the memory element

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US6967863B2 (en) * 2004-02-25 2005-11-22 Grandis, Inc. Perpendicular magnetization magnetic element utilizing spin transfer
US6992359B2 (en) * 2004-02-26 2006-01-31 Grandis, Inc. Spin transfer magnetic element with free layers having high perpendicular anisotropy and in-plane equilibrium magnetization
JP4134080B2 (en) 2005-04-04 2008-08-13 Tdk株式会社 Magnetoresistive element and manufacturing method thereof, magnetoresistive device, thin film magnetic head, head gimbal assembly, head arm assembly, and magnetic disk device
US8194436B2 (en) * 2007-09-19 2012-06-05 Nec Corporation Magnetic random access memory, write method therefor, and magnetoresistance effect element
US9929211B2 (en) * 2008-09-24 2018-03-27 Qualcomm Incorporated Reducing spin pumping induced damping of a free layer of a memory device
US7936598B2 (en) * 2009-04-28 2011-05-03 Seagate Technology Magnetic stack having assist layer

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JPH08274386A (en) * 1995-03-31 1996-10-18 Mitsubishi Electric Corp Electromagnetic transducer element
JPH1187803A (en) * 1997-09-09 1999-03-30 Sanyo Electric Co Ltd Magnetic resistance effect element
JP3679593B2 (en) * 1998-01-28 2005-08-03 キヤノン株式会社 Magnetic thin film element, magnetic thin film memory element and recording / reproducing method thereof
JP3559722B2 (en) * 1999-04-16 2004-09-02 キヤノン株式会社 Magnetoresistive element, solid-state memory
FR2817998B1 (en) * 2000-12-07 2003-01-10 Commissariat Energie Atomique SPIN POLARIZATION MAGNETIC DEVICE WITH MAGNIFICATION ROTATION, MEMORY AND WRITING METHOD USING THE DEVICE

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