• Title/Summary/Keyword: Tunnel Junction

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Rapid Theraml Annealing Effect on the Magnetic Tunnel Junction with MgO Tunnel Barrier (MgO 절연막을 갖는 자기 터널 접합구조에서의 급속 열처리 효과)

  • Min, Kiljoon;Lee, Kyungil;Kim, Taewan;Jang, Joonyeon
    • Journal of the Korean Magnetics Society
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    • v.25 no.2
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    • pp.47-51
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    • 2015

  • To achieve a high tunneling magneto resistance (TMR) of sputtered magnetic tunnel junctions (MTJs) with an MgO barrier, the annealing process is indispensable. The structural and compositional changes as consequences of the annealing greatly affect the spin-dependent transport properties of MTJs. Higher TMR could be obtained for MTJs annealed at higher annealing temperature. The diffusion of Ru, Mn and/or Ta in the MTJs may occur during annealing process, which is known to be detrimental to spin-dependent tunneling effect. The rapid thermal annealing (RTA) process was used for annealing the MTJs with synthetic antiferromagnets. To suppress the diffusion of Mn, Ru and/or Ta in the MTJs, the process time and temperature of RTA were minutely controlled.

  • https://doi.org/10.4283/JKMS.2015.25.2.047 인용 PDF KSCI

Etching of MTJ (Magnetic Tunnel Junction) in an ICP Etching System for STT-MRAM applications

  • Park, Jong-Yun;Gang, Se-Gu;Jeon, Min-Hwan;Yeom, Geun-Yeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.169-169
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    • 2011

  • STT-MRAM (수직자화 자기메모리)는 자화반전 현상을 원리로 구동하는 비휘발성 메모리로 기존의 메모리 장치에 비해 빠른 접근 속도와 높은 저장 밀도를 가지며 영구적인 기록이 가능하다. 이러한 장점들에 더해 적은 소모 전력을 지니므로 기존의 SRAM등의 한계를 극복할 대안으로 각광받고 있으며 차세대 메모리 군의 선두주자로 가장 적합한 후보중 하나이다. STT-MRAM의 건식 식각 방식에 있어 가장 큰 이슈는 소자 구동에 핵심적인 역할을 하는 MTJ(Magnetic Tunnel Junction)의 식각이다. MTJ는 free layer, tunnel barrier, pinned layer 3개의 층으로 구성되어 있으며 양 끝 layer에는 강자성체인 CoFeB가 사용되고 tunnel barrier에는 절연층인 MgO가 사용되고 있다. 이러한 물질들은 기존의 반도체 소자에서는 사용되지 않았던 물질들로 기존 공정에서 사용되던 Cl2 based plasma etching에서는 측벽에 비화발성 반응물과 잔류 Cl2에 의해 부식이 발생하는 문제점이 드러나고 있다. 이러한 문제점을 해결하기 위한 새로운 대안으로 CO/NH3/Ar나 CH4/Ar 같은 새로운 가스 조합을 사용하는 연구가 진행되고 있다. 이러한 연구에 의해 기존의 Cl2 plasma를 이용한 식각에서 나타나는 문제점은 해결이 되었으나 또 다른 문제점들이 보고되고 있다. 본 연구에서는 stack MRAM sample을 사용하여 기존의 사용되는 Cl2/Ar plasma와 대안 gas인 CO/NH3, CH4/Ar plasma에서의 식각을 진행하였으며 실험 조건(gas 비율 변화, Bias power 변화, 식각 시간)에 따른 식각 속도의 변화나 식각 후의 profile에 대하여 관찰하였다. 이에 따라 식각후에 어떠한 차이점이 있는 지를 알아보았으며 CO/NH3나 CH4/Ar plasma에서 식각시 나타나는 문제점에 대하여도 조명해 보았다.

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Effect of Ti Concentration on the Microstructure of Al and the Tunnel Magnetoresistance Behaviors of the Magnetic Tunnel Junction with a Ti-alloyed Al-oxide Barrier (Ti 첨가에 따른 Al 미세구조 변화 효과와 산화 TiAl 절연층을 갖는 자기터널접합의 자기저항 특성)

  • Song, Jin-Oh;Lee, Seong-Rae
    • Journal of the Korean Magnetics Society
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    • v.15 no.6
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    • pp.311-314
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    • 2005

  • We investigated the composition dependence of the tunneling magnetoresistance (TMR) behavior and the stability of the magnetic tunnel junctions (MTJs) with TiAlOx barrier and the microstructural evolution of TiAl alloy films. The TMR ratio increased up to $49\%$ at $5.33\;at\%$ Ti. In addition, a significant tunneling magnetoresistance (TMR) value of $20\%$ was maintained after annealing at $450^{\circ}C$, and the breakdown voltage ($V_B$) of and 1.35 V were obtained in the MTJ with $5.33\;at\%$ Ti-alloyed AlOx barrier. These results were closely related to the enhanced quality of the barrier material microstructure in the pre-oxidation state. Ti alloying enhanced the barrier/electrode interface uniformity and reduced microstructural defects. These structural improvements enhanced not only the TMR effect but also the thermal and electrical stability of the MTJs.

  • https://doi.org/10.4283/JKMS.2005.15.6.311 인용 PDF KSCI

A study on the fire smoke diffusion delay strategy in a great depth underground double deck tunnel junction (대심도 복층터널 교차로 화재연기 확산지연 방안 연구)

  • Shin, Tae-Gyun;Moon, Jung-Joo;Yang, Yong-Won;Lee, Yun-Taek;Han, Jae-Hee
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.1
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    • pp.115-126
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    • 2019

  • Recently, in order to solve the traffic congestion in urban areas and to improve the peripheral environment, research on the design and construction technology development of great depth underground double-deck tunnel is under way by using the underground space in the urban area. The network type double-deck tunnel is in the form of an intersection with a small cross section and a steep slope as per construction at the base of a flatland, so that the fire smoke spreads rapidly in case of fire, which is expected to cause damage of human life. Therefore, this study is analyzed the delay effect of fire smoke diffusion according to the installation and non - installation of delay system for fire smoke diffusion at the intersection. Fire fumes were delayed up to 270 seconds when the delay system for fire smoke diffusion was installed at the intersection and it is analyzed that the greater the operating area of the delay system for fire smoke diffusion, the more preventable the damage of human life of the intersection.

  • https://doi.org/10.9711/KTAJ.2019.21.1.115 인용 PDF KSCI HTML