JPH05308018A - Magnetically soft thin film - Google Patents

Abstract

PURPOSE:To obtain a magnetically soft thin film having an excellent high frequency characteristic because of its less permeability attenuation in a band of 100MHz or higher and suitable for an inductor or transformer material used in the band by limiting the ratio of the magnetic layer thickness to the non-magnetic layer thickness to a specified range. CONSTITUTION:A magnetic layer composed of Fe and nitrogen and a nitride non-magnetic layer are alternately deposited; the thickness of each magnetic layer is within the range from 5 angstrom to 50 angstrom inclusive, and the ratio of the magnetic layer thickness to the non-magnetic layer thickness is within the range of 1-5. This provides a magnetically soft thin film excellent in high frequency characteristic because of its less permeability attenuation in a band of 100MHz or higher, which makes it suitable for a material for inductors and transformers used in the band. As shown in the figure, even in case a non-magnetic metal nitride is used for the non-magnetic layer, there is a region where an excellent permeability is shown when its thickness is 50 angstroms or below; however, the permeability is rapidly degraded when the thickness of the Fe nitride. layer is 100 angstroms or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic thin film exhibiting soft magnetic characteristics, and more particularly to a soft magnetic thin film used as a material for inductors, transformers and the like used in a high frequency region of 100 MHz or higher.

[0002]

2. Description of the Related Art With the progress of weight reduction and high integration of electronic equipment parts, miniaturization of inductors and transformers is required.
Conventionally, ferrite chips have been used for such a trend. However, in ferrite, the saturation magnetic flux density of the material itself is low, so that a resonance phenomenon occurs in a high frequency region, and there is a problem that it cannot cope with higher frequencies for further miniaturization in the future. Therefore, an inductor and a transformer using an amorphous metal ultrafine wire having a higher saturation magnetic flux density have been proposed (JP-A-63-220521).

[0003]

On the other hand, in recent years FeC / F
A metal magnetic thin film having a high saturation magnetic flux density and excellent soft magnetic characteristics, which is obtained by stacking e of several e to several tens of angstroms, has also been proposed and is mainly used for magnetic recording. By the way, such a soft magnetic thin film abruptly attenuates the magnetic permeability at 50 MHz or more, and cannot be used for a magnetic device such as an inductor which operates in a high frequency region of 100 MHz or more.

By the way, recently, researches on crystalline Fe nitrides have become active. The Fe nitride thin film is formed by introducing nitrogen gas during film formation such as sputtering, and a low coercive force of 2 Oe has been reported with a high saturation magnetic flux density of 2.1 T or more (IEEE Trans.Magn.MAG-20. , 1451 (198
Four) ). A magnetic material in which the Fe nitride and a non-magnetic oxide such as SiO ₂ are alternately laminated to have a film thickness of 50 angstroms or more is also proposed (Proceedings of the 14th Applied Magnetics Society Academic Lectures 281 (1990)). ), The magnetic permeability is low at 400 to 600 at a frequency of 5 MHz and is not suitable for high frequency applications.

The present invention has been made in view of the above circumstances, and has a small attenuation of magnetic permeability in a band of 100 MHz or more and excellent high frequency characteristics, and is a soft magnetic material suitable as a material for inductors and transformers used in this region. The purpose is to provide a thin film.

[0006]

In order to solve the above-mentioned problems, the present invention has magnetic layers composed of Fe and nitrogen and nitride non-magnetic layers alternately laminated in sequence, the magnetic layers having a thickness of 50 angstroms or less. The ratio of the film thickness of the magnetic layer to the non-magnetic layer is in the range of 1 to 5.

[0007]

By configuring as described above, 100
It is suitable as a material for inductors and transformers used in this region because it has a small attenuation of magnetic permeability in the band of MHz or more and excellent high frequency characteristics.

[0008]

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

[0009] prior art Fe nitride is the SiO ₂ of the laminate rapidly magnetic properties especially permeability is deteriorated in film thickness of 100 angstroms or less. This is due to the fact that the nonmagnetic layer is an oxide, so that oxygen is diffused into the magnetic layer, or there is no similarity in crystal structure. Therefore, as a result of intensive studies conducted by the present inventors, even when the nonmagnetic layer is made of a nonmagnetic metal nitride as shown in FIG. 1, the magnetic permeability is certainly high when the Fe nitride layer has a film thickness of 100 angstrom. It was found that there is a region having excellent magnetic permeability at a film thickness of 50 angstroms or less, although it deteriorates rapidly.

A magnetic material obtained by alternately stacking a Fe nitride film and a non-magnetic metal nitride film with a film thickness of 50 angstroms or less is F
Although the saturation magnetic flux density of the e-nitride film itself is slightly lower than that in the case where the film thickness is 50 angstroms or more, 100M
Excellent characteristics with small attenuation of magnetic permeability can be obtained in a high frequency region of Hz or higher. For this purpose, the ratio of the film thickness of the magnetic layer made of the Fe nitride layer to the nonmagnetic layer made of the nonmagnetic metal nitride layer is in the range of 1 to 5. When the film thickness of the magnetic layer exceeds 50 angstroms, the saturation magnetic flux density Bs of the film as a whole is large, but as described above, the permeability is greatly attenuated, and when the film thickness is 5 angstroms or less, the saturation magnetic flux density Bs rapidly increases. descend. When the film thickness ratio is 1 or less, the coercive force increases due to the interaction of the magnetic layers, and the saturation magnetic flux density Bs of the laminated magnetic body decreases, which cannot be put to practical use. When it is 5 or more, the non-magnetic metal nitride layer is small and the resistivity is low, and the permeability is attenuated at high frequencies, which is not suitable for the purpose of the present invention. In the present invention, the Fe-based nitride film is b. c. c. It is based on the structure,
As a result of nitrogen being incorporated into the Fe lattice, the structure becomes distorted. Non-magnetic metal nitride film has an electric resistance of 10 ¹⁰ μΩcm
The above is desirable, and a semi-metal nitride film such as aluminum or silicon is preferable. The present invention will be described below with reference to specific examples. (Invention)

Planar type high frequency magnetron sputtering equipment
Input power 5W / cm² , Total pressure 3mTor
r, nitrogen partial pressure 3%, substrate temperature 30 ° C., glass base
An Fe film is formed on the plate by 5 to 50 angstrom. next
Input power 25W / cm² , Total pressure 3mTorr, nitrogen content
AlN film (non-magnetic) under the conditions of pressure 20% and substrate temperature 30 ° C.
The ratio of the magnetic film (FeN film) thickness to the AlN film thickness.
To be 1 to 5
The film thickness should be about 2 μm. The film composition at this time
The magnetic properties are shown in FIG. In addition, the 8-shaped coil is electromagnetic
Typical measured by the method of measuring the induced voltage
The high frequency characteristics of the magnetic permeability of this film are shown in FIG. (Comparative example)

The film thickness of the sputtered film in Fe nitrogen is 100 angstroms or more, and the magnetic film (FeN film) is made of AlN.
The magnetic thin film is formed under the same conditions as in the specific examples except that the ratio of the film thickness to the film is 1 or less and 5 or more. The film structure and magnetic characteristics at this time are shown in FIG. 3B and 3C show examples of frequency characteristics of magnetic permeability obtained by the same method as that of the concrete example.

[0013]

As described above, according to the present invention, 10
It is suitable for use as a material for inductors and transformers that will be used in this region in the future, because it has a small attenuation of magnetic permeability in the band of 0 MHz or more and is excellent in high frequency characteristics.

Although the FeN magnetic film is used in the above embodiment, it is of course possible to include a noble metal such as Pt or Ru to the extent that the magnetic characteristics are not significantly deteriorated in order to improve the corrosion resistance.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between a layer thickness of FeN and magnetic permeability measured at a frequency of 100 MHz under an applied magnetic field of 10 mOe.

FIG. 2 is an explanatory diagram showing an example of film configurations and magnetic characteristics of specific examples of the present invention and comparative examples.

3 is an example No. 3 in FIG. 5 and Comparative Example No. 1
It is a characteristic view which shows the frequency characteristic of magnetic permeability in the applied magnetic field of 10 mOe of the films of 5 and 16.

[Explanation of symbols]

A ... Frequency characteristics of magnetic permeability for specific examples of the present invention, B, C ... Frequency characteristics of magnetic permeability for comparative examples.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeo Fujii, Inventor, Shigeo Fujii, No. 1 112, Gongen Moriyama, Imozawa, Aoba-ku, Sendai-shi, Miyagi Amorphous Electronic Devices Laboratory Co., Ltd. (72) Fumio Matsumoto, Aoba, Sendai-shi, Miyagi 1 112, Moriyama, Gongen, Izawa, Ku-ku Amorphous Electronic Devices Research Institute Co., Ltd. (72) Inventor Kei'an Fujimori 2-20-3 Yoshinari Yoshinari, Aoba-ku, Sendai-shi, Miyagi (72) Inventor Ken Masumoto Aoba, Sendai-shi, Miyagi Prefecture 3-8-22 ward Uesugi

Claims (1)

[Claims] 1. A magnetic thin film comprising a magnetic layer made of Fe and nitrogen and a nitride non-magnetic layer which are sequentially laminated, wherein the magnetic layer has a film thickness of 5 angstroms or more and 50 angstroms or less. A soft magnetic thin film having a thickness ratio of 1 to 5 with respect to the magnetic layer.