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Magnetic tunnel junction device

外国特許コード F110005387
整理番号 K02012US3
掲載日 2011年9月5日
出願国 アメリカ合衆国
出願番号 92364310
公報番号 20110031570
公報番号 8319263
出願日 平成22年9月30日(2010.9.30)
公報発行日 平成23年2月10日(2011.2.10)
公報発行日 平成24年11月27日(2012.11.27)
国際出願番号 JP2005004720
国際公開番号 WO2005088745
国際出願日 平成17年3月10日(2005.3.10)
国際公開日 平成17年9月22日(2005.9.22)
優先権データ
  • 特願2004-071186 (2004.3.12) JP
  • 特願2004-313350 (2004.10.28) JP
  • 2005US-10591947 (2005.3.10) US
  • 2005WO-JP04720 (2005.3.10) WO
発明の名称 (英語) Magnetic tunnel junction device
発明の概要(英語) (US8319263)
The output voltage of an MRAM is increased by means of an Fe(001)/MgO(001)/Fe(001) MTJ device, which is formed by microfabrication of a sample prepared by the following steps.
A single-crystalline MgO (001) substrate 11 is prepared.
An epitaxial Fe(001) lower electrode (a first electrode) 17 with the thickness of 50 nm is grown on a MgO(001) seed layer 15 at room temperature, followed by annealing under ultrahigh vacuum (2×10-8 Pa) and at 350° C.
A MgO(001) barrier layer 21 with the thickness of 2 nm is epitaxially formed on the Fe(001) lower electrode (the first electrode) at room temperature, using a MgO electron-beam evaporation.
A Fe(001) upper electrode (a second electrode) with the thickness of 10 nm is then formed on the MgO(001) barrier layer 21 at room temperature.
This is successively followed by the deposition of a Co layer 21 with the thickness of 10 nm on the Fe(001) upper electrode (the second electrode) 23.
The Co layer 21 is provided so as to increase the coercive force of the upper electrode 23 in order to realize an antiparallel magnetization alignment.
特許請求の範囲(英語) [claim1]
1. A magnetoresistive device having a tunnel barrier junction structure, the magnetoresistive device comprising: a first ferromagnetic material layer of BCC structure;
a second ferromagnetic material layer of a BCC structure; and
a tunnel barrier layer located between the first and second ferromagnetic material layers, and
wherein the tunnel barrier layer comprises:
a single-crystalline magnesium oxide layer in which (001) crystal plane is preferentially oriented or a poly-crystalline magnesium oxide layer in which (001) crystal plane is preferentially oriented, and
wherein the tunnel barrier layer has a tunnel barrier height omega in a range of 0.2 to 0.5 eV.
[claim2]
2. The magnetoresistive device according to claim 1, wherein at least one of the first and second ferromagnetic material layers comprises CoFeB alloy.
[claim3]
3. The magnetoresistive device according to claim 1, wherein said tunnel barrier height psi is obtained by fitting J-V characteristics of the tunnel barrier junction structure to an equation (1)
J=[(2mpsi )1/2/DELTA s](e/h)2 * exp[-(4 pi DELTA s/h) * (2mpsi )1/2] * V (1)
where J is a tunnel current density flowing through the tunnel barrier layer, V is an applied bias voltage that is 100 mV or smaller, m is a mass of the free electron, e is the elementary electric charge, h is the Planck's constant, DELTA s is an effective thickness of the tunnel barrier layer that is approximately equivalent to (TMgO-0.5 nm), and tMgO is an actual thickness of the tunnel barrier layer determined using a cross-sectional transmission electron microscope image.
[claim4]
4. The magnetoresistive device according to claim 3, wherein at least one of the first and second ferromagnetic material layers comprises CoFeB alloy.
  • 発明者/出願人(英語)
  • YUASA SHINJI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
  • NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
国際特許分類(IPC)
参考情報 (研究プロジェクト等) PRESTO Nanostructure and Material Property AREA
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