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Magnetic tunnel junction device and memory device including the same

外国特許コード F110005388
整理番号 K02012WO
掲載日 2011年9月5日
出願国 アメリカ合衆国
出願番号 59194705
公報番号 20070195592
公報番号 7884403
出願日 平成17年3月10日(2005.3.10)
公報発行日 平成19年8月23日(2007.8.23)
公報発行日 平成23年2月8日(2011.2.8)
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
  • 2005WO-JP04720 (2005.3.10) WO
発明の名称 (英語) Magnetic tunnel junction device and memory device including the same
発明の概要(英語) (US7884403)
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 tunnel barrier layer;
a first ferromagnetic material layer of a BCC structure formed on a first side of said tunnel barrier layer; and
a second ferromagnetic material layer of the BCC structure formed on a second side of said tunnel barrier layer, wherein
said tunnel barrier layer is formed by a single-crystalline MgOx (001) (0<x<1) or a poly-crystalline MgOx (0<x<1) in which (001) crystal plane is preferentially oriented, and
wherein a tunnel barrier height between a bottom of a conduction band of said tunnel barrier layer and a Fermi energy of at least one of said first and second ferromagnetic layers is a discontinuous value in a range of 0.2 to 0.5 eV.
[claim2]
2. The magnetoresistive device according to claim 1, wherein said ferromagnetic material comprises a single-crystalline (001) of Fe or Fe-based alloy, or a poly-crystalline of Fe or Fe-based alloy in which (001) crystal plane is preferentially oriented.
[claim3]
3. The magnetoresistive device according to claim 1, wherein a magnetoresistance ratio of said magnetoresistive device is more than 70%.
[claim4]
4. The magnetoresistive device according to claim 1, wherein said first ferromagnetic material layer comprises CoFeB alloy.
[claim5]
5. A magnetoresistive device, comprising: a first ferromagnetic material layer of a BCC structure;
a second ferromagnetic material layer of the BCC structure; and
a magnesium oxide layer located between said first ferromagnetic material layer and said second ferromagnetic material layer, wherein
said magnesium oxide is a single-crystalline (001) or a poly-crystalline crystalline in which (001) crystal plane is preferentially oriented,
wherein said magnesium oxide has oxygen vacancy defects, and
wherein said magnesium oxide has a tunnel barrier height in a range of 0.2 to 0.5 eV.
[claim6]
6. A magnetoresistive device having a magnetic tunnel junction structure comprising: a tunnel barrier layer;
a first ferromagnetic material layer of a BCC structure formed on a first side of said tunnel barrier layer; and
a second ferromagnetic material layer of the BCC structure formed on a second side of said tunnel barrier layer, wherein
said tunnel barrier layer comprises a poly-crystalline MgO in which (001) crystal plane is preferentially oriented, said MgO having oxygen vacancy defects,
wherein said tunnel barrier layer has a tunnel barrier height of 0.2 to 0.5 eV, and
wherein a magnetoresistance ratio of said device is more than 70%.
[claim7]
7. A magnetoresistive device having a magnetic tunnel junction structure, the magnetoresistive device comprising: a tunnel barrier layer;
a first ferromagnetic material layer of a BCC structure formed on a first side of said tunnel barrier layer; and
a second ferromagnetic material layer of the BCC structure formed on a second side of said tunnel barrier layer, wherein
said tunnel barrier layer comprises a poly-crystalline magnesium oxide having oxygen vacancy defects in which (001) crystal plane is preferentially oriented,
said tunnel barrier layer has a tunnel barrier height of 0.2 to 0.5 eV, and
a magnetoresistance ratio of said device is more than 70%.
[claim8]
8. A memory device comprising: a transistor; and
a magnetoresistive device comprising a tunnel barrier layer;
a first ferromagnetic material layer of a BCC structure formed on a first side of said tunnel barrier layer; and
a second ferromagnetic material layer of the BCC structure formed on a second side of said tunnel barrier layer, wherein
said tunnel barrier layer is formed by a single-crystalline MgOx (001) (0<x<1) or a poly-crystalline MgOx (0<x<1) in which (001) crystal plane is preferentially oriented, wherein
a tunnel barrier height of said tunnel barrier layer is in a range of 0.2 to 0.5 eV and said magnetoresistive device is used as a load for said transistor.
  • 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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