JPH0547555A - Amorphous soft magnetic thin film and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing an amorphous soft magnetic multilayered thin film very excellent in high frequency characteristics of permeability or inductance and bias-resistant magnetic characteristics. CONSTITUTION:Amorphous magnetic layers and insulating layers are alternately laminated to form a multilayered film, where the magnetic layers are made to shift from each other by a certain angle in an easy magnetization direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous soft magnetic multilayer thin film used for magnetic core materials such as inductors and transformers used in a high frequency band, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for inductors and transformers for use in a high frequency band from the viewpoint of miniaturization and high performance of electronic devices, and accordingly, a material having excellent soft magnetic characteristics in a high frequency region as a magnetic core material. Is desired. Ferrite, amorphous alloys, etc. have been used as such soft magnetic materials for magnetic cores.

[0003]

When used in a high frequency band, it is inevitable to make the material thinner. Ferrite has a very high specific resistance ρ but a low saturation magnetic flux density Bs, and the thin film does not have a spinel structure necessary for soft magnetism. On the other hand, although the amorphous alloy has a specific resistance ρ that is inferior to that of ferrite, it is an order of magnitude larger than that of a crystalline alloy, and the saturation magnetic flux density Bs is considerably larger than that of ferrite, so that it is suitable for thinning.

When a magnetic core thin film for use in a high frequency band is formed using this amorphous alloy, the film is usually formed in a uniaxial magnetic field, and a nonmagnetic insulating layer such as ceramics is alternately laminated with a magnetic layer. A multilayer film having uniaxial magnetic anisotropy is used. It is a general method to apply a magnetic field to such a multilayer film in the direction of the hard axis to apply a high frequency band. This usually maintains the characteristics up to the resonance frequency, but is not always satisfactory.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an amorphous soft magnetic multilayer thin film excellent in high frequency characteristics of magnetic permeability or inductance and excellent resistance to bias magnetic field and a method for manufacturing the same. And

[0006]

In order to solve the above-mentioned problems, the present invention provides a method of controlling the easy magnetization direction of each magnetic layer when producing a multilayer film in which amorphous magnetic layers and insulating layers are alternately laminated. It is characterized in that the magnetic layer is applied with a different angle every time the magnetic layer is formed.

[0007]

By the above means, the present invention is an amorphous soft magnetic multilayer thin film which is excellent as a magnetic core for use in a high frequency band having a very high natural resonance frequency, for example, exceeding 100 MHz.

That is, according to the present invention, when a multilayer film in which an amorphous magnetic layer and an insulating layer are alternately laminated is manufactured, the easy magnetization direction of each magnetic layer is set to an angle within the film plane for each film formation of the magnetic layer. By offsetting and applying the film, it is possible to obtain an amorphous soft magnetic multilayer thin film having extremely excellent high frequency characteristics of magnetic permeability μ or inductance L and excellent bias magnetic field resistance characteristics.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The multilayer thin film of the present invention is produced by alternately laminating an amorphous alloy magnetic layer and an insulating layer such as an oxide or a nitride by a sputtering method or the like, but the composition of the amorphous alloy is not limited. In particular, a material having excellent soft magnetic characteristics in a high frequency region, high saturation magnetic flux density, magnetostriction close to zero, and high electric resistivity is suitable. The thickness of the insulating layer is not particularly limited as long as it is within the range usually used. Since the magnetic layer imparts uniaxial magnetic anisotropy during its film formation, it is always formed in a uniaxial magnetic field. The feature of the present invention lies in the lamination conditions of this magnetic layer. That is, it is an essential condition that the easy magnetization direction of each magnetic layer deviates from the magnetic layer immediately above or below the insulating layer by an arbitrary angle in the film plane. The multilayer thin-film magnetic core obtained by the method of the present invention as described above is extremely excellent in the identity of the magnetic permeability μ or the inductance L even in the region close to GHz. Specific examples of the present invention will be shown below. Specific Example-1 A multilayer thin film was formed under the following conditions using a high frequency sputtering device. Target: Magnetic material: Co ₈₆ Nb ₉ Zr ₅ (atomic%) Insulator: SiO ₂ Sputtering condition: Atmosphere gas: Ar Substrate magnetic field: 80 Oe Film thickness: CoNbZr: 0.25 μm / layer SiO ₂ : 0.17 μm / layer Stacking period : 4 (4 layers each) Lamination condition: The easy magnetization direction of the first magnetic layer is 0 °. Easy magnetization direction of the second magnetic layer: + 45 ° to the first layer Easy magnetization direction of the third magnetic layer: + 90 ° to the first layer Easy magnetization direction of the fourth magnetic layer: −45 ° to the first layer The easy magnetization direction was given by appropriately shifting the magnetic field direction on the substrate surface each time the magnetic layer was formed.

For comparison, a uniaxial magnetic anisotropic multilayer film was manufactured under exactly the same conditions as the present invention except for the stacking conditions. Magnetic permeability μ and inductance L are measured by width 10 mm × length 10 m
The measurement was performed on a sample of m size. The exciting magnetic field was applied perpendicular to the easy magnetization direction of the comparative sample. The result is shown in FIG.

That is, the comparative sample has a magnetic permeability μ in the low frequency region,
The inductance L shows a high value, but its frequency stability is obviously inferior to that of the sample of the present invention, and is about 20 MHz.
As described above, the separation started from the linearity and the sharp decrease occurred.
On the other hand, the sample of the present invention has a magnetic permeability μ of about 2000.
The homogeneity is maintained up to 500 to 600 MHz, which indicates that the sample has extremely high frequency stability. Specific Example-2

Regarding the thin film of the sample of the present invention and the uniaxially anisotropic sample thin film of the comparative sample, which were produced under the same conditions as in the specific example-1, a thin film to be measured S as shown in FIG. ), A DC magnetic field (Hdc) was applied up to 10 Oe in the direction perpendicular to the above, and the effect on the bias magnetic field was observed.

The results are shown in FIG. 2A shows the case of the comparative sample, where A1 is the easy axis (Easy axi).
When a magnetic field is applied in the s) direction, A2 is the hard axis (Ha
When a magnetic field is applied in the rdaxis direction, A3 is a blank case. FIG. 2B shows the case of the sample of the present invention, where B1 is the easy magnetization direction (Easy direc).
when a magnetic field is applied to the hard magnetic direction (Hard direction), and when a magnetic field is applied to the hard direction (B2), B3 is a blank case. That is, as shown in FIG. 2, it is apparent that the sample of the present invention is stable against an external magnetic field (bias magnetic field Hdc) of several Oe.

[0015]

As described above, according to the present invention, when a multilayer film in which an amorphous magnetic layer and an insulating layer are alternately laminated is prepared, the easy magnetization direction of each magnetic layer is set to the magnetic layer formation. It was found that an amorphous soft magnetic multi-layered thin film with extremely excellent high-frequency characteristics of magnetic permeability or inductance and anti-bias magnetic field characteristics can be obtained by shifting the angle within the film plane for each film. The effect on the industrial world is great.

[Brief description of drawings]

FIG. 1 is an amorphous soft magnetic multilayer thin film according to a sample of the present invention,
FIG. 3 is a characteristic diagram showing an example of frequency dependence of magnetic permeability and inductance of a normal uniaxial magnetic anisotropic amorphous multilayer magnetic thin film as a comparative sample.

FIG. 2 is a characteristic diagram showing an example of a bias magnetic field characteristic of a normal uniaxial magnetic anisotropic amorphous multilayer magnetic thin film as compared with the amorphous soft magnetic multilayer thin film related to the sample of the present invention.

FIG. 3 is an explanatory diagram showing an example of the relationship between the thin film to be measured and the magnetic field according to the present invention.

[Explanation of symbols]

 S ... Thin film to be measured.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location H01F 17/04 K 7129-5E 27/24 41/02 B 8019-5E 41/18 7371-5E ( 72) Inventor Fumio Matsumoto 1 112 112 Gongen Moriyama, Aoba-ku, Aoba-ku, Sendai-shi, Miyagi Amorphous Electronic Devices Laboratory Co., Ltd. 72) Inventor Ken Masumoto 3-8-22 Uesugi, Aoba-ku, Sendai City, Miyagi Prefecture

Claims (2)

[Claims] 1. In an amorphous soft magnetic multilayer thin film in which an amorphous magnetic layer and an insulating layer are alternately laminated, the easy magnetization direction of each magnetic layer is deviated by an arbitrary angle in the film plane every time the magnetic layer is formed. An amorphous soft magnetic multi-layered thin film. 2. A method of manufacturing an amorphous soft magnetic multilayer thin film, which comprises manufacturing a multilayer film in which an amorphous magnetic layer and an insulating layer are alternately laminated, wherein an easy magnetization direction of each magnetic layer is set every time the magnetic layer is formed. A method for producing an amorphous soft magnetic multilayer thin film, characterized in that the film is applied with a different angle in the film plane.