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Development of double tunneling junctions and their application to MRAM

Research Project

Project/Area Number 13355026
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section展開研究
Research Field Structural/Functional materials
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

INOMATA Koichiro  Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (90323071)

Co-Investigator(Kenkyū-buntansha) SAITO Yoshiaki  Research and Developed Center, Toshiba Corporation, Senior Researcher, 研究開発センター・記憶材料デバイスラボ, 主任研究員(研究職)
TEZUKA Nobuki  Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (40323076)
Project Period (FY) 2001 – 2002
Project Status Completed (Fiscal Year 2002)
Budget Amount *help
¥51,740,000 (Direct Cost: ¥39,800,000、Indirect Cost: ¥11,940,000)
Fiscal Year 2002: ¥11,570,000 (Direct Cost: ¥8,900,000、Indirect Cost: ¥2,670,000)
Fiscal Year 2001: ¥40,170,000 (Direct Cost: ¥30,900,000、Indirect Cost: ¥9,270,000)
KeywordsMRAM / spin switching / synthetic antiferromagnetic coupled film / MFM / tunnel magnetoresistance / annealing / MRAM / スピントンネル接合 / 微細加工 / 磁気抵抗効果
Research Abstract

Magnetic random access memory (MRAM) using TMR memory cells possesses the attractive properties of non-volatility, radiation hardness, nondestructive readout, low voltage, high access time, unlimited read and write endurance and high density. The TMR, however, significantly decreases with increasing bias voltage, which leads to reduction of the signal voltage for the actual MRAM. A ferromagnetic double tunneling junction (DTJ) was proposed for the high density MRAM application. It was demonstrated that a large signal voltage over 100 mV can be obtained using DTJ because of the smaller degradation of the TMR for the bias voltage, which is significantly higher than 30 mV of the conventional single junctions.
The arrays of the synthetic antiferromagnetic (SyAF) patterned bits consisting of Co_<90>Fe_<10>(t_1 nm)/Ru(d nm)/Co_<90>Fe_<10>(t_2 nm) were successfully fabricated with micron to submicron sizes and different aspect ratios. Magnetization switching field H_<sw> and magnetic domain st … More ructure were investigated using magneto-optical Kerr effect (MOKE) and magnetic force microscopy (MFM), respectively. It was demonstrated that the strongly AF-coupled SyAF with aspect ratio k = 1 creates size-independent H_<sw> down to submicron sizes fabricated, which is understood by zero demagnetization field for k = 1 and single domain structure observed by MFM. The size-independent switching field demonstrates the predominance of the SyAF for ultra high bit density MRAMs, requiring a low switching field and stabilized single domain. The size-independent spin switching field was also observed in magnetic tunnel junctions (MTJs) using a SyAF free layer consisting of Co_<90>Fe_<10> (t_1) / Ru (0.5 nm) / Co_<90>Fe_<10>(t_2) , which was deposited on a thermal oxidized Si substrate using an ultrahigh vacuum sputtering system, and patterned using an electron beam lithography and Ar ion milling into micron to submicron sizes. A SyAF free layer can keep high remanence even for the aspect ratio of 1, and exhibits the size-independent spin switching field in all element widths from 16 to 0.25 μm investigated. Additionally, the MTJs using a SyAF free layer consisting of Co_<90>Fe_<10> (3 nm) /Ru (0.5 nm) / Co_<90>Fe_<10> (1.5 nm) show a TMR ratio 40% after annealing at 250℃. These results demonstrate that a SyAF free layer is an available structure for spin-electronics nano-devices including MRAMs. Less

Report

(3 results)
  • 2002 Annual Research Report   Final Research Report Summary
  • 2001 Annual Research Report
  • Research Products

    (26 results)

All Other

All Publications (26 results)

  • [Publications] 小池 伸幸: "反平行結合膜の微細加工素子における磁化状態"日本応用磁気学会誌. 27巻. 316-319 (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] N.Tezuka: "Magnetization reversal and domain structure of antiferromagnetically coupled submicron elements"J.Appl.Phys.. 93(in print). (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] N.Tezuka: "Single domain observation for synthetic antiferromagnetically coupled bits with low aspect ratios"Appl.Phys.Lett.. 82. 606-608 (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K.Inomata: "Magnetic switching field and giant magnetoresistance effect of multilayers with synthetic antiferromagnetic free layers"Appl.Phys.Lett.. 81. 310-312 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] 野崎 隆行: "反平行結合フリー層を用いたGMRスピンバルブ膜の磁化反転特性"日本金属学会誌. 66巻. 1078-1082 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] N.Tezuka: "Switching fields behavior in antiparallely coupled submicrometer scale magnetic elements"J.Magn.Magn.Matter.. 240. 294-296 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K.Inomata: "MRAM技術"Sipec. 206 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] N. Koike et al.: "Magnetization state and spin-switching field in antiferromagnetically coupled submicron elements"J. Mag. Soc. Japan. 27. 316-319 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] N. Tezuka et al.: "Magnetization reversal and domain structure of antiferromagnetically coupled submicron elements"J. Appl. Phys.. 93(in print). (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] N. Tezuka et al.: "Single domain observation for synthetic antiferromagnetically coupled bits with low aspect ratios"Appl. Phys. Lett.. 82. 606-608 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K. Inomata et al.: "Magnetic Switching field and giant magnetoresistance effect of multilayers with synthetic antiferromagnetic free layers"Appl. Phys. Lett.. 81. 310-312 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] T. Nozaki et al.: "Magnetic switching properties of GMR spin-valves using SyAF Free layers"J. Japan Inst. Metals. 66. 1078-1082 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] N. Tezuka et al.: "Switching fields behavior in antiparallely coupled sub-micron scale magnetic elements"J. Magn. Magn. Matter.. 240. 294-296 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K. Inomata et al.: "MRAM Technology"sipec.

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] 小池 伸幸: "反平行結合膜の微細加工素子における磁化状態"日本応用磁気学会誌. 27巻・4号. 316-319 (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] N.Tezuka: "Magnetization reversal and domain structure of antiferromagnetically coupled submicron elements"J. Appl. Phys.. 93・10(印刷中). (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] N.Tezuka: "Single domain observation for synthetic antiferromagnetically coupled bits with low aspect ratios"Appl. Phys. Lett.. 82・4. 606-606 (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] K.Inomata: "Magnetic switching field and giant magnetoresistance effect of multilayers with synthetic antiferromagnetic free layers"Appl. Phys. Lett.. 81・2. 310-312 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] 野崎 隆行: "反平行結合フリー層を用いたGMRスピンバルブ膜の磁化反転特性"日本金属学会誌. 66巻・11号. 1078-1082 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] N.Tezuka: "Switching fields behavior in antiparallely coupled sub-micrometer scale magnetic elements"J. Magn. Magn. Matter. 240. 294-296 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] K.Inomata: "MRAM技術"Sipec. 206 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] N.Tezuka: "Switching field behavior in an Antiparallely coupled sub-micrometer scale magnetic element"Journal of magnetism and magnetic materials. (印刷中). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] K.Inomata: "Magnetic switching of antiferromagnetically coupled deep submicron devices"Journal of Applied Physics. (印刷中). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] 北川 英二: "サブミクロン反平行結合膜のスピン反転挙動"日本応用磁気学会誌. (印刷中). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] E.Kitagawa: "Magnetization reversal of synthetic antiferromagnetically coupled deep submicron elements"Proceeding of ICMFS. (印刷中). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] 猪俣 浩一郎: "スピントンネル2重接合のTMR"電気学会マグネティックス研究会資料. MAG01-13 9. 17-21 (2001)

    • Related Report
      2001 Annual Research Report

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Published: 2001-04-01   Modified: 2016-04-21  

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