JPH0574643A - Manufacture of soft magnetic thin film - Google Patents

Abstract

(57) [Summary] [Object] To obtain a magnetic thin film having a saturation magnetic flux density of 20 kG or more and excellent soft magnetic properties. [Structure] When a Fe—Co based alloy thin film containing Co ≦ 70 at% is formed on a substrate by a sputtering method, the sputtering gas pressure P [Pa] is 0. 09 + x / 400 ≤ P ≤ 0.70 ...
The relationship of (1) is satisfied. Further preferably, the sputtering gas is Ar, and the sputtering gas pressure P “Pa” is
The relationship of the formula (1) with respect to the Co content x [at%] and the following formula 0.07 + x / 200 ≤ P ≤ 0.20 + x / 2
The relationship of 00 is satisfied at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an Fe--Co alloy soft magnetic thin film having a high saturation magnetic flux density and good soft magnetism.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic equipment, the thinning of magnetic devices has been pursued, and there has been a demand for a thin film magnetic material which simultaneously satisfies a high saturation magnetic flux density and excellent soft magnetic characteristics. As a soft magnetic material having a high saturation magnetic flux density, Fe-C having a composition near Fe-35 wt% Co
It is known that the o-based alloy exhibits the highest saturation magnetic flux density among known metal-based magnetic materials. However, it has been difficult to obtain satisfactory properties in terms of soft magnetism in this alloy-based thin film material. For example, H.264. R. Ph
ilipp and J. J. Tiemann: J. A
ppl. Phys. 43 (1972) 3542, the magnetization of the thin film of Fe-50 wt% Co shows a high value of 22 kG, but its coercive force is about 20 Oe, which is worse than that of the bulk material. on the other hand,
Although softening of the Fe-Co alloy thin film has been attempted by adding various elements, for example, M. Hayaka et
al. : IEEE Trans. Magn. , MAG
As described in -23 (1987) 3092, there is a problem that the saturation magnetic flux density is significantly reduced as compared with the Fe-Co binary system.

[0003]

In view of the above problems, the present invention provides a thin film soft magnetic material of Fe--Co system which has excellent soft magnetic characteristics while ensuring a high saturation magnetic flux density of 20 kG or more. The purpose is to propose a manufacturing method.

[0004]

For the above purpose, Fe
As a result of investigating the magnetic characteristics by preparing various —Co alloy thin films, in the method of preparing the Fe—Co alloy by the sputtering method, the sputtering gas pressure was set to Fe—Co.
It was found that the soft magnetic characteristics can be improved without reducing the saturation magnetic flux density by adjusting according to the composition ratio of.

That is, according to the present invention, in the method of forming the Fe—Co alloy thin film containing Co ≦ 70 at% on the substrate by the sputtering method, the sputtering gas pressure P [Pa] is the Co content x [at]. %] With respect to 0.09 + x / 400 ≤ P ≤ 0.70 (1), and in this method, the sputtering gas is Ar. , The sputtering gas pressure P [Pa] is
It is characterized in that the relation of the above formula (1) and the relation of the formula (2) 0.07 + x / 200 ≦ P ≦ 0.20 + x / 200 (2) are simultaneously satisfied with respect to the Co content x [at%]. It is a method of manufacturing a soft magnetic thin film.

[0006]

[Function] The reason why the composition of the alloy material is limited will be described below. Hereinafter, at% is simply expressed as%. Fe to C
When o is added, the saturation magnetic flux density Bs increases, and takes a maximum value of about 24.5 kG in the composition around 35% Co as described above, and when the Co content is further increased, the value decreases, but 70% Bs exceeding Fe when:
Indicates. However, when it exceeds 70%, Bs falls below the value of Fe and the purpose of high saturation magnetic flux density cannot be achieved. Therefore, the Co content is set to 70% or less.

Further, the Fe-Co alloy thin film has the effects of increasing the electrical resistivity, improving the high frequency characteristics, and improving the corrosion resistance. Al, Si, Ti, V, Cr, M
One or more of n, Nb, Mo, Ta and W may be contained. However, when the total content of these elements exceeds 5%, the saturation magnetic flux density is remarkably lowered, so that the total content of these elements is preferably 5% or less. In addition, up to 15% of the total of Fe and Co is Ni.
In the case of substituting with, the corrosion resistance can be imparted without significantly lowering the saturation magnetic flux density.
Can be included.

The thin film manufacturing method according to the present invention includes:
Film forming methods such as direct current or high frequency sputtering are suitable. The sputtering gas may be Ar, Xe, another inert gas, or a mixed gas thereof. As described above, by adjusting the sputtering gas pressure according to the Co content, it is possible to improve the soft magnetic properties of the Fe—Co thin film such as a decrease in coercive force and an increase in magnetic permeability.

[0009]

[Examples] Examples will be described below. [Example 1] Fe-C having various composition ratios shown in Table 1
A film was formed on a glass substrate by a direct current sputtering method using an o-based alloy target and Ar as a sputtering gas. The Ar pressure was changed in the range of 0.12 to 1.0 Pa. The film thickness was about 2000Å in the central part of the substrate. About 6 mm in diameter from the center of the substrate of the thin film sample
The test piece of No. 1 was cut out and the DC magnetic characteristics were measured using a vibrating sample magnetometer. Table 1 shows the coercive force and the saturation magnetic flux density obtained from this measurement. From this measurement result, it is clear that the coercive force becomes good when the sputtering gas pressure is within the range of the above-mentioned formula (1).

[0010]

[Table 1]

[Embodiment 2] No. 1 of the first embodiment. A Fe-Co alloy target having a composition of 1 to 4 was used to form a film on a glass substrate by a DC sputtering method. The sputtering gas is Ar, and the Ar pressure is 0.10 to 1.
The range was 0 Pa. The film thickness is about 2000 at the center of the substrate.
Å A test piece having a diameter of about 6 mm was cut out from the center of the substrate of the prepared thin film sample, heat-treated at 300 ° C. for 1 hr in vacuum, and the DC magnetic characteristics of the test piece were measured using a vibrating sample magnetometer. The value of the coercive force obtained by this measurement is shown in FIG. From this measurement result, it is apparent that the coercive force becomes extremely good when the sputtering gas pressure is within the range of the above-mentioned formula (2).

[0012]

As described above, since the magnetic thin film of the present invention has a high saturation magnetic flux density and excellent magnetic properties at the same time, it can be used to downsize a magnetic device for electronic equipment,
Higher performance can be achieved and industrial profit is great.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between Co content, Ar pressure and coercive force.

Claims (2)

[Claims] 1. Fe-Co containing Co ≦ 70 at%.
When a system alloy thin film is formed on a substrate by a sputtering method, the sputtering gas pressure P [Pa] is 0.09 + x / 400 ≤ P ≤ 0.70 with respect to the Co content x [at%] (1) The method of manufacturing a soft magnetic thin film, characterized in that 2. The manufacturing method according to claim 1, wherein the sputtering gas is Ar, and the sputtering gas pressure P “Pa” is as follows with respect to the Co content x [at%] and the relationship of the equation (1). A method of manufacturing a soft magnetic thin film, which simultaneously satisfies the relationship of formula 0.07 + x / 200 ≦ P ≦ 0.20 + x / 200.