Magnetic tunnel junction device

• US 8,405,134 B2
• Filed: 02/20/2012
• Issued: 03/26/2013
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan), Japan Science And Technology Agency
• Inventors: Yuasa, Shinji
• Primary Examiner(s): Chambliss, Alonzo
• Application Number:
  US13/400,340
• Publication Number:
  US 20120161262A1
• Time in Patent Office: 400 Days
• Field of Search: None
• US Class Current: 257/295
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11C 11/15 using multiple magnetic layers G11C11/155 takes precedence
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H01F 10/132 containing cobalt
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01L 28/55 with a dielectric comprising a perovskite structure material
• CPC Class Codes: H10B 53/30 characterised by the memory core region
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details
• CPC Class Codes: H10N 50/85 Magnetic active materials
• CPC Class Codes: H10N 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one galvanomagnetic or Hall-effect element covered by groups H10N50/00 - H10N52/00 MRAM devices H10B61/00

Abstract

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 as follows: A single-crystalline MgO (001) substrate is prepared. An epitaxial Fe(001) lower electrode (a first electrode) is grown on a MgO(001) seed layer at room temperature, followed by annealing under ultrahigh vacuum. A MgO(001) barrier layer 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) is then formed on the MgO(001) barrier layer at room temperature. This is successively followed by the deposition of a Co layer on the Fe(001) upper electrode (the second electrode). The Co layer is provided so as to increase the coercive force of the upper electrode in order to realize an antiparallel magnetization alignment.

Claims

1. A magnetoresistive device having a tunnel barrier junction structure, the magnetoresistive device comprising:

a first ferromagnetic material layer deposited on a substrate;

a second ferromagnetic material layer; and

a tunnel barrier layer located between the first and second ferromagnetic material layers, and

wherein said tunnel barrier layer comprises a single-crystalline magnesium oxide in which (001) crystal plane is preferentially oriented or a poly-crystalline magnesium oxide in which (001) crystal plane is preferentially oriented, and

at least said first ferromagnetic material layer is crystallized and comprises CoFeB alloy.

2. The magnetoresistive device according to claim 1, wherein said second ferromagnetic material layer is also crystallized and comprises CoFeB alloy.

3. A magnetoresistive device having a tunnel barrier junction structure, the magnetoresistive device comprising:

a first ferromagnetic material layer deposited on a substrate;

a second ferromagnetic material layer; and

a tunnel barrier layer located between the first and second ferromagnetic material layers, and

wherein said tunnel barrier layer comprises a single-crystalline magnesium oxide in which (001) crystal plane is preferentially oriented or a poly-crystalline magnesium oxide in which (001) crystal plane is preferentially oriented, and

wherein at least said first ferromagnetic material layer is entirely crystallized and comprises CoFeB alloy.

4. The magnetoresistive device according to claim 3, wherein said second ferromagnetic material layer is also entirely crystallized and comprises CoFeB alloy.