JP2910409B2 - Magnetoresistance effect element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistance effect element using a giant magnetoresistance effect material.

[0002]

2. Description of the Related Art A magnetoelectric element utilizing the ferromagnetic magnetoresistance effect has good sensitivity to a small magnetic field strength, and is of a magnetic flux response type, so that highly accurate measurement can be performed even at a low-speed magnetic field change. It is advantageous in that it can be manufactured in a small size by using a magnetic field sensor, and is widely used for a magnetic field sensor, a magnetic head, and the like. Conventionally, such a magnetoresistive effect element has Ni
A ferromagnetic thin film of an Fe alloy or a NiCo alloy is used, and a so-called anisotropic magnetoresistance effect is used. In these magnetoresistive elements, the axis of easy magnetization of the ferromagnetic thin film is usually set in the direction perpendicular to the direction of the detection magnetic field.
The rate of change in magnetoresistance of a conventional magnetic thin film utilizing the anisotropic magnetoresistance effect is 2 to 5%, and a magnetic thin film having a larger rate of change in magnetoresistance has been demanded.

Recently, a magnetic multilayer film in which a NiFe thin film and a Co thin film are alternately stacked, and a non-magnetic thin film layer is interposed between the stacked magnetic thin films, can obtain a large magnetoresistance change rate of about 10% at room temperature. (Yamamoto et al., 14th
Annual Meeting of the Japan Society of Applied Magnetics).

[0004]

However, in such a magnetoresistive element using a so-called giant magnetoresistive material, a large output is required unless the easy axis of magnetization of the ferromagnetic thin film is set parallel to the direction of the detection magnetic field. There was a problem that it could not be obtained.

[0005]

The magnetoresistive element of the present invention comprises two types of ferromagnetic thin film layers having different coercive forces alternately stacked on a substrate, and a nonmagnetic thin film layer interposed between the stacked magnetic thin film layers. In a magnetoresistive effect element using a magnetic multilayer film having the above-mentioned structure, a groove is provided on the substrate in parallel with a direction of a detection magnetic field.

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 is a structural diagram showing an example of the magnetoresistance effect element of the present invention. A ferromagnetic film layer 2 and a ferromagnetic thin film layer 3 having a smaller coercive force than the ferromagnetic thin film layer 2 are alternately stacked on a substrate 1, and a non-magnetic thin film layer 4 is interposed between the stacked magnetic thin film layers. further,
Electrodes are attached to these multilayer films to form a magnetoresistive element.

In FIG. 1, the lamination starts from the magnetic layer 2 on the substrate 1 and ends at the magnetic layer 3, but the effect of the present invention does not depend on the lamination order of the magnetic layers 2 and 3. In order to improve the crystal structure and magnetic properties of the magnetic layer, a base layer made of a nonmagnetic material such as Au, Cu, Ag, or PtCr may be provided on the base.

The material of the substrate 1 according to the present invention is glass,
Si, Al ₂ O ₃ , TiC, SiC, Al ₂ O ₃ and Ti
A sintered body with C, ferrite, or the like can be used. Various ferromagnetic materials can be used for the material of the magnetic thin film layer 2, but Co, CoPt, CoCr, CoCrPt,
A hard magnetic material such as NiCo or an alloy containing these as a main component is suitable. Various ferromagnetic materials can be used for the magnetic thin film layer 3;
A Co-based amorphous alloy such as Fe, FeAlSi, iron nitride, and CoZr, or a material obtained by adding an additive thereto is particularly suitable. The thickness of these magnetic layers is 200 A (angstrom) or less, preferably 100 A or less.
If the thickness exceeds the above range, the effect of the present invention is not improved, and the productivity is reduced. Although there is no particular lower limit on the thickness of the magnetic thin film, if the thickness is 4 A or more, it is easy to keep the film thickness uniform, and the film quality becomes good.

Further, the non-magnetic metal thin film layer 4 according to the present invention
Is a conductive material that plays a role in weakening the magnetic interaction between the magnetic thin film layers 2 and 3, and specifically, Au, Cu, Ag, Pt, or a material to which an additive is added can be used. The above two types of ferromagnetic material and non-magnetic metal material
Evaporate with a vacuum evaporation apparatus having three evaporation sources or a sputtering apparatus having three targets, and alternately open and close the shutters of three evaporation sources, or alternately pass three substrates over the evaporation sources. This makes it possible to alternately laminate three types of materials on the substrate.

In the magnetoresistive element of the present invention, a groove parallel to the direction of the magnetic field detected by the MR element is provided on the surface of the substrate by mechanical polishing, chemical polishing, or fine processing using photolithography. A large change in magnetoresistance is obtained.

[0011]

The operation of the magnetoresistance effect element of the present invention will be described below. In a conventional magnetoresistive element using an anisotropic magnetoresistive material, the resistance becomes maximum when the magnetization of the ferromagnetic layer is parallel to the sense current direction, and the resistance is increased when the magnetization direction is rotated by 90 ° by the detection magnetic field. Will be minimal. That is, the maximum resistance change is obtained when the magnetization direction is rotated by 90 °. Therefore, the axis of easy magnetization of the ferromagnetic layer is normally set perpendicular to the direction of the detected magnetic field.

On the other hand, in a magnetoresistive element using a giant magnetoresistive material, the resistance becomes maximum when the magnetization directions of the two types of ferromagnetic layers are antiparallel.
The resistance becomes minimum when the magnetization directions of the ferromagnetic layers become parallel. That is, the maximum resistance change is obtained when the magnetization direction of the one having the soft magnetic property of the two types of ferromagnetic layers is rotated by 180 °. Therefore, in order to obtain the maximum resistance change as an element, the easy axis of magnetization of the ferromagnetic layer must be set in parallel with the direction of the detection magnetic field. In the magnetoresistive element of the present invention, the easy axis of magnetization of the ferromagnetic layer can be made parallel to the direction of the detection magnetic field by providing a groove parallel to the direction of the detection magnetic field on the substrate surface.

[0013]

Embodiments of the present invention will be described below. The substrate 1 was polished in a fixed direction using alumina abrasive grains and provided with a groove having a depth of about 100A. A Cr underlayer having a thickness of 50 A is formed on a substrate by an electron beam vacuum evaporation method, and a Co layer 2 having a thickness of 10 A and a Ni layer having a thickness of 10 A are formed thereon.
The Fe layers 3 were alternately and continuously laminated five times via the Cu layer 4 having a thickness of 40A. The substrate temperature was 200 ° C., the film formation rate was 0.1 nm / sec, and the film thickness of each layer was controlled by changing the opening and closing time of the shutter of each evaporation source. The degree of vacuum during evaporation is 5
It was ⁸ Torr ^- × 10. Further, in the same manner as in the example, a magnetic multilayer film was formed on a glass substrate on which no groove processing was performed, and the result was used as a comparative example.

In order to measure the magnetoresistance effect of these multilayer films, a Au film having a thickness of 0.2 μm is formed on the multilayer film by a vapor deposition method, and a fine wire having a width of 5 μm is formed using a photolithography technique and an ion etching technique. It was patterned. Next, only the 5 μm length of the detection portion was removed by chemical etching of the Au layer, and the remaining Au film was used as the electrode 5. At this time,
In the examples, processing was performed so that the groove direction on the substrate was parallel to the width direction of the fine line pattern. 10m to these samples
A constant current of A was applied, and the resistance-magnetic field characteristics were measured by the two-terminal method. Table 1 shows the results.

[0015]

[Table 1]

As is evident from the measurement results in Table 1, the magnetoresistance effect element of the present invention has a large resistance change compared to the case where no groove is provided on the substrate, and a large output is obtained when the magnetoresistance effect element is used. Can be

[0017]

As described above, the magnetoresistive element of the present invention has two kinds of ferromagnetic thin films having different coercive forces alternately stacked on a substrate, and a nonmagnetic thin film layer is interposed between the stacked magnetic thin films. In a magnetoresistive effect element using a magnetic multilayer film having a structure having a structure in which a groove parallel to a direction of a detection magnetic field is provided on the substrate, an extremely large magnetoresistance change is obtained, and a high-output magnetoresistance effect is obtained. It is suitable for an element.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing one example of a magnetoresistance effect element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Magnetic thin film layer 3 Magnetic thin film layer 4 Nonmagnetic thin film layer 5 Electrode

Claims (1)

(57) [Claims] 1. A two kinds of ferromagnetic thin layers having different coercive forces are stacked alternately on the substrate, a magnetic resistance of a magnetic multilayer film comprising a structure obtained by interposing a non-magnetic thin film layer to each laminated magnetic thin film layers In the effect element, a groove parallel to a detection magnetic field direction is provided on the substrate.