Magnetic tunnel element and its manufacturing method, thin-film magnetic head, magnetic memory and magnetic sensor

• US 20020114112A1
• Filed: 01/29/2002
• Published: 08/22/2002
• Est. Priority Date: 02/06/2001
• Status: Active Grant

• Current Assignee: Dexerials Corporation
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nakashio, Eiji, Sugawara, Junichi, Onoe, Seiji
• Granted Patent: US 6,760,201 B2
• Time in Patent Office: Days
• US Class Current: 360/324.2
• 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: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32
• CPC Class Codes: H10B 61/10 comprising components having two electrodes, e.g. diodes or MIM elements
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A magnetic tunnel element (1) including a plurality of ferromagnetic films (5, 9) laminated across an insulating film (11) formed of metal oxide films (6, 7, 8) and in which asymmetric tunnel barriers are formed along the direction in which the ferromagnetic films (5, 9) are laminated by this insulating film (11) (6, 7, 8). There are also constructed a thin-film magnetic head, a magnetic memory and a magnetic sensor, each of which includes the magnetic tunnel element (1). Since a magnetoresistive ratio can be suppressed from being lowered by decreasing a bias voltage dependency, there are provided a highly-reliable magnetic tunnel element which can obtain a high output when the magnetic tunnel element is applied to a thin-film magnetic head and the like and a method of manufacturing such a magnetic tunnel element. When a magnetic head, a magnetic memory and a magnetic sensor include this magnetic tunnel element, they become highly reliable and also become able to obtain a high output.

Claims

1. A magnetic tunnel element comprising:

a plurality of ferromagnetic layers; and

an insulating film formed of metal oxide films, wherein said plurality of ferromagnetic layers are laminated across said insulating film and asymmetric tunnel barriers are formed by said insulating film along the direction in which said plurality of ferromagnetic layers are laminated.

2. A magnetic tunnel element according to claim 1, wherein a bias voltage is applied to said magnetic tunnel element in such a manner that a potential increases on the higher barrier side of said asymmetric tunnel barriers.

3. A magnetic tunnel element according to claim 1, wherein said metal oxide films are formed of at least no less than one kind of metal oxide films selected from among an aluminum oxide film, a tantalum oxide film and a magnesium oxide film.

4. A method of manufacturing a magnetic tunnel element comprising a plurality of ferromagnetic films and an insulating film formed of metal oxide films wherein said plurality of ferromagnetic films are laminated across said insulating film, comprising at least the steps of:

depositing a metal film and forming a first metal oxide film by oxidizing said metal film; and

depositing a metal film on said first metal oxide film and forming a second metal oxide film by oxidizing said metal film under oxidation conditions different from those of said process for forming said first metal oxide film, thereby to form said insulating film.

5. A thin-film magnetic head comprising:

a magnetic tunnel element including a plurality of ferromagnetic films and an insulating film formed of metal oxide films wherein said plurality of ferromagnetic films are laminated across said insulating film and asymmetric tunnel barriers are formed along the direction in which said plurality of ferromagnetic layers are laminated by said insulating film; and

upper and lower magnetic shields laminated across said magnetic tunnel element.

6. A magnetic memory comprising:

a bit line;

a word line; and

a magnetic tunnel element including a plurality of ferromagnetic films and an insulating film formed of metal oxide films wherein said plurality of ferromagnetic films are laminated across said insulating film and asymmetric tunnel barriers are formed along the direction in which said plurality of ferromagnetic films are laminated by said insulating film, wherein a memory cell including said magnetic tunnel element is disposed corresponding to an intersection between said bit line and said word line.

7. A magnetic sensor comprising:

a magnetic tunnel element including a plurality of ferromagnetic films and an insulating film formed of metal oxide films wherein an asymmetric barrier is formed along the direction in which said plurality of ferromagnetic films are laminated by said insulating film; and

upper and lower magnetic shields laminated across said magnetic tunnel element.