JPH04236405A - Soft magnetic thin film - Google Patents

Abstract

PURPOSE:To obtain superior corrosion resistance while soft magnetic characteristics and heat resistance are maintained, by adding Ni to an Fe-N based soft magnetic thin film in which specified elements are introduced. CONSTITUTION:The composition of the title thin film is expressed by (FeaMbNic)dNeOf where a, b, c, d, e and f show compositions by atomic %, and M shows at least one kind selected out of Si, Al, Ta, B, Mg, Ca, Sr, Ba, Cr, Mn, Zr, Nb, Ti, Mo, V, W, Hf, Ga, Ge, and rare earth elements, and the composition range is O.1$ b(5, 0.5<=c<=10, a+b+c<=100, 0.5<=e<=15, 0.1<=f<=13, and d=100-e-f. When Ni is introduced in an Fe-N based soft magnetic thin film in which specified addition elements are introduced, corrosion resistance can be improved while permeability, coercive force and saturation magnetization are maintained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fe--N soft magnetic thin film, and particularly to improving its corrosion resistance.

0002

BACKGROUND OF THE INVENTION In the field of magnetic recording, higher density recording and shorter wavelength recording are progressing, and along with this, magnetic recording media are required to have high coercive force and high residual magnetic flux density. On the other hand, magnetic head materials are required to have high saturation magnetic flux density, high magnetic permeability, and low coercive force in order to take advantage of the characteristics of the magnetic recording medium.

[0003] Fe-N based materials have been known as one of the soft magnetic materials that meet these demands, and are made into thin films using vapor phase plating techniques such as sputtering and used as core materials for magnetic heads. It is being considered to do so.

However, Fe--N based soft magnetic thin films have a drawback of poor thermal stability. In the manufacture of magnetic heads, a fusing process using glass with a high melting point is essential to ensure reliability, and this process requires high-temperature heat treatment, so the above drawbacks are a major problem. Become.

Under these circumstances, research on improving the thermal stability of Fe-N based soft magnetic thin films continues.
For example, in Japanese Patent Application No. 2-46322, the applicant of the present application has introduced Fe-
We reported that the thermal stability of N-based soft magnetic thin films was improved.

[0006]

[Problems to be Solved by the Invention] However, the Fe-N based soft magnetic thin film into which the above-mentioned additive elements have been introduced does not have sufficient corrosion resistance, and a magnetic head using such a soft magnetic thin film as a core material is When stored under high temperature and high humidity conditions,
Rust gradually occurs and magnetic properties such as coercive force and saturation magnetic flux density deteriorate. For this reason, it lacks practicality as a magnetic head, and is a major obstacle to commercialization.

[0007] The present invention was proposed in view of the above-mentioned conventional circumstances, and provides a material that has corrosion resistance, does not rust even when stored under high temperature and high humidity conditions, and has good softness. The purpose is to provide a soft magnetic thin film with magnetic properties and high saturation magnetic flux density.

[0008]

[Means for Solving the Problem] As a result of intensive research to achieve the above-mentioned object, the present inventors have come to the knowledge that adding Ni is effective in improving corrosion resistance. Ta. The present invention was completed based on such knowledge. That is, the present invention provides (Fea Mb N
ic )dNe Of (However, a, b, c, d, e
, f represents the composition as atomic %, M is Si, Al, Ta
, B, Mg, Ca, Sr, Ba, Cr, Mn, Zr, N
b, represents at least one of Ti, Mo, V, W, Hf, Ga, Ge, and a rare earth element. ), and its composition range is 0.1≦b≦5 0.5≦c≦10 a+b+c=100 0.5≦e≦15 0.1≦f≦13 d=100−e−f It is characterized by:

[0009] Each of the above-mentioned compositions is determined in consideration of magnetic properties such as soft magnetic properties and saturation magnetic flux density, heat resistance, and corrosion resistance. In particular, when Ni is introduced, the amount of Ni introduced depends on the amount of Ni in the metal components. The content should be 0.5 to 10 at%. If too little Ni is introduced, no improvement in corrosion resistance can be expected; on the other hand, if too much Ni is introduced,
The coercive force Hc comes to show a large value. At this time, if it is desired to ensure even higher magnetic permeability, the amount of Ni introduced is preferably 0.5 to 8 atomic % in the metal component. Further, the amount of oxygen introduced is 0.1 to 13 atomic %. If the amount of oxygen introduced is too small or too large, no improvement in thermal stability can be expected; for example, the coercive force H after annealing cannot be expected.
c comes to show a large value.

The above-mentioned soft magnetic thin film is produced by a thin film forming technique such as sputtering, but the method for introducing the additive element is to first prepare an alloy of the desired element and Fe, and then use this alloy as a target or evaporation source. One possible method is to use it as Alternatively, chips of each element may be placed on the Fe target and sputtered simultaneously.

[0011]Also, as a method for introducing nitrogen or oxygen, a method using a nitride or oxide as a target or vapor deposition source may be considered, but it is usually achieved by introducing nitrogen or oxygen into the atmosphere.

The soft magnetic thin film to which the present invention is applied may be a single layer film, or may be made of magnetic metal such as permalloy, Ag, Cu, etc.
It may also be a multi-layered film divided by non-magnetic metals such as Si--N, SiO2 or other ceramic materials.

The above-mentioned soft magnetic thin film is used as a magnetic core in a so-called metal-in-gap type magnetic head, etc. by forming a film on a ferrite, and by integrating these magnetic cores by glass fusing, the magnetic head is formed. It is generally configured. At this time, there is a possibility that the reaction between the soft magnetic thin film of the present invention and the glass or the soft magnetic thin film due to heating during glass fusing may cause a problem. Therefore, when applying the soft magnetic thin film of the present invention to a metal-in-gap type magnetic head, etc., silicon oxide or silicon nitride should be used between the glass and the soft magnetic thin film, or between the ferrite and the soft magnetic thin film. It is preferable to provide a very thin film as a reaction prevention film. In particular, the reaction prevention film between glass and soft magnetic thin film is silicon oxide film, silicon nitride film, and metal chromium film. It is effective to form a laminated film with a chromium compound film.

The silicon oxide film or silicon nitride film is also formed by a thin film forming technique such as sputtering, and the film thickness is 30 to 100 Å for a reaction prevention film between the ferrite and the soft magnetic thin film. It is preferable. If the thickness of the reaction prevention film is less than 30 Å, the reaction cannot be sufficiently suppressed, and if it exceeds 100 Å, it may act as a pseudo gap. For a reaction prevention film between glass and a soft magnetic thin film, the thickness is preferably 30 to 500 Å. If it is less than 30 Å, the reaction cannot be sufficiently suppressed. Although there is no need to specify an upper limit, it is desirable to set it to 500 Å or less from the viewpoint of productivity and the like. Metal chromium films and chromium compound films are provided for the purpose of ensuring bonding strength with glass, etc., and are also formed by thin film forming techniques such as sputtering, but the film thickness is different from that of the silicon oxide film or the chromium compound film. 30 Å to 500 Å for the same reason as in the case of silicon nitride film.
It is preferable that

[0015]

[Operation] When Ni is introduced into a Fe--N soft magnetic thin film into which predetermined additive elements have been introduced, corrosion resistance is improved while maintaining magnetic permeability, coercive force, and saturation magnetization. This is considered to be because Ni acts directly on Fe to suppress oxidation. Moreover, in the case of Ni, since it is difficult to form a nitride, even after sputtering is performed in a nitrogen atmosphere, most of Ni remains in the form of metal Ni and is alloyed with Fe. Therefore, it is presumed that it acts effectively on Fe and exhibits an excellent corrosion-resistant effect. Furthermore, the addition of Ni
Since Ni is a ferromagnetic element, the amount of saturation magnetization decreases little due to addition, which is advantageous in maintaining magnetic properties.

[0016]

EXAMPLES The present invention will be explained below based on specific experimental results.

Experimental Example 1 This experimental example is an example in which Ni, Cr, Cu, and Mo were introduced into a Fe-N soft magnetic thin film into which predetermined elements had been introduced, and the corrosion resistance and soft magnetic properties were investigated. .

First, an alloy target containing Fe as a main component was prepared, and RF sputtering was performed in an argon atmosphere containing nitrogen gas and oxygen gas to form a thin film having the composition shown in Table 1.

[0019] The conditions for sputtering are an output of 30
The temperature was 0 W, the gas pressure (total pressure) was 1.2 mTorr, and the thickness of the thin film was 3 μm. Further, the nitrogen content and oxygen content in the film were controlled by the amount of nitrogen gas and oxygen gas introduced into the atmosphere.

The corrosion resistance and coercive force of each of the thin films thus prepared were measured before and after the annealing treatment. The results are shown in Table 1. The annealing treatment was performed at a temperature of 550°C for 1 hour, and the corrosion resistance was determined by measuring the polarization resistance of the thin film in a 3% NaCl solution at a low current of 100 μA, and calculating the reciprocal of the measured resistance value. Evaluated by. In addition, for comparison, the corrosion resistance and magnetic properties of a blank sample in which no additive elements were introduced were also measured in the same manner.

[0020]

[Table 1]

Looking at Table 1, sample 1 containing Ni
are samples 2 to 5 in which elements other than Ni were introduced.
It can be seen that it has excellent corrosion resistance and maintains good soft magnetic properties. For example, in samples 2 and 3 in which Cr, which is generally thought to improve corrosion resistance, was introduced, no improvement in corrosion resistance was observed, and compared to the blank sample, the coercive force was larger and the soft magnetic properties deteriorated. are doing. On the other hand, in Sample 1, the corrosion resistance was significantly improved while maintaining a low coercive force. Therefore, from these results,
Addition of N to Fe-N magnetic material into which predetermined additive elements have been introduced
It has been shown that the introduction of i is effective in obtaining a thin film with excellent corrosion resistance and soft magnetic properties.

Experimental Example 2 In this experimental example, Ni was added at various concentrations to a Fe--N based soft magnetic thin film into which a predetermined element had been introduced, and the corrosion resistance and soft magnetic properties were investigated.

First, a thin film having the composition shown in Table 2 was prepared in the same manner as in Experimental Example 1. The produced thin film was then measured for corrosion resistance, magnetic permeability, and coercive force before and after the annealing treatment. The results are shown in Table 2.

Note that the conditions for annealing treatment and the method for evaluating corrosion resistance are the same as in Experimental Example 1. Also, for comparison, Ni
Corrosion resistance, magnetic permeability, and coercive force were similarly measured for a blank sample without the addition of .

[0025]

[Table 2]

Looking at Table 2, it can be seen that the corrosion resistance after annealing treatment improves as the amount of Ni added increases. However, when the amount added exceeds 12 at %, the coercive force shows a large value of 2.8, making it impossible to obtain good soft magnetic properties. Therefore, in order to obtain good corrosion resistance and soft magnetic properties, the amount of Ni added in the metal component must be 0.5 to 1.
It was found that it is preferable to set the content to 0 atomic %. Furthermore, it has been shown that in order to obtain even higher magnetic permeability, it is sufficient to add Ni in an amount of 0.5 to 8 atomic % to the metal component.

[0027]

[Effects of the Invention] As is clear from the above explanation, in the present invention, Ni is added to the Fe-N based soft magnetic thin film into which predetermined elements have been introduced, so that the soft magnetic properties and heat resistance are improved. It is possible to obtain excellent corrosion resistance while maintaining the same. Therefore, if such a soft magnetic thin film is used as the core material of a magnetic head, it is possible to obtain a highly practical magnetic head that is resistant to rust even when stored under high temperature and high humidity conditions.

Claims (1)

[Claims] [Claim 1] (Fea Mb Nic)d Ne
Of (however, a, b, c, d, e, f represent the composition as atomic %, M is Si, Al, Ta, B, Mg, C
a, Sr, Ba, Cr, Mn, Zr, Nb, Ti, Mo
, V, W, Hf, Ga, Ge, and a rare earth element. ), and its composition range is 0
．． A soft magnetic thin film characterized in that 1≦b≦5 0.5≦c≦10 a+b+c=100 0.5≦e≦15 0.1≦f≦13 d=100−e−f.