JPH02152208A - Soft magnetic alloy film - Google Patents

Abstract

PURPOSE:To enhance a soft magnetic characteristic by a method wherein a composition of Co-M-N (where M represents at least one kind or more out of Ti, Zr, Hf, Nb, Ta, Mo and W) is provided and its composition ratio is specified so that a magnetostriction of conventional Co-based nitride alloy films can be approached to zero. CONSTITUTION:This is soft magnetic alloy film which is expressed by a formula of CoaMbNc (where M represents at least one kind or more out or Ti, Zr, Hf, Nb, Ta, Mo and W, Co represents cobalt and (a), (b) and (c) represent atomic % individually) and which is composed of a composition where said (a), (b) and (c) are 50<=a<=75, 4<=b<=25, 20.1<=c<=35 and a+b+c=100. By a heat treatment, this M is bonded chemically to N contained in the film; a fine crystal of MN (a nitride of M) is provided. Thereby, Co as a mother phase displays a fine crystal structure composed mainly of a face-centered cubic system. Since the crystal becomes fine (a particle diameter of 0.05mum or lower), an influence by a crystal magnetic anisotropy is relaxed and a soft magnetic characteristic can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a soft magnetic film used in composite magnetic heads (MIG heads) and the like, and in particular has excellent thermal stability. Concerning materials with excellent soft magnetic properties.

[Prior Art] Conventionally, among the soft magnetic films used in the above-mentioned magnetic heads, etc., Go-M-N ( However, M
A soft magnetic film has been proposed having the following composition: represents at least one of Ti, Zr, HfNbMo to V. (JP-A-62-210607, JP-A-63-5
No. 7758, etc.) [Problems to be Solved by the Invention] However, conventional Co-M-N based soft magnetic films exhibit negative magnetostriction due to heat treatment, and have a comparatively low magnetostriction of -4 to -6 x 10-6. Due to the large magnetostriction, the soft magnetic properties tend to deteriorate due to the reverse magnetostrictive effect caused by strain during processing into a magnetic head.

In addition, when manufacturing a magnetic head using this Co-M-N-based soft magnetic film, it is necessary to bond a pair of magnetic core half-holes by glass bonding, so the magnetic core half-holes are usually attached during glass bonding. , which is heated to a high temperature of around 600°C. However, when the magnetic core is heated to such an I3i high temperature, the electrical resistance (specific resistance) of the soft magnetic film decreases to 80 to 100 μΩ・cm (approximately 70% of the conventional co-M amorphous film). becomes. When the electrical resistance decreases, eddy current loss at high frequencies increases and 1
, there was a disadvantage that the high-frequency magnetic permeability stopped increasing.

In addition, since this conventional Co-M thin film cannot obtain good soft magnetic properties with a single layer, it has a structure in which Go-M thin films and Co-M films are laminated alternately (the one after heat treatment is It is necessary to create a structure in which N diffuses between the layers and the N concentration is modulated in the direction of the film thickness, which has the disadvantage of complicating the manufacturing process of the soft magnetic film.

The present invention aims to improve the soft magnetic properties and high frequency permeability by bringing the magnetostriction of the conventional Co-based nitride alloy film close to zero and increasing the electrical resistance. The purpose of this study is to provide a soft magnetic alloy film exhibiting good soft magnetic properties (7).

[Means for Solving the Problems] In order to achieve the above object, the invention according to claim 1 has the following features: CoaMbNc (where M is i''i).

At least one of Zr, Hf, Jb, Ta, Mo, and W, Go is cobalt, N is nitrogen, and a,
b, c each represent atomic %), and the above a, b, c
The soft magnetic alloy film has the following composition: 50≦a≦75 4≦b≦25 20 1≦c≦35 a+b+c=100.

Further, the invention according to claim 2 is a soft magnetic alloy film that includes fine crystals of the nitride of M, and is entirely composed of fine crystals with a grain size of 005 μm or less.

The present invention will be explained in more detail below.

In the above-mentioned soft magnetic alloy film, Co (cobalt) is the main component and is an element responsible for magnetism. (denoted as %) is required. Further, in order to obtain soft magnetism, a≦75 at% must be satisfied.

-1-M (T i, Z r, Hr, N b,
Mo, W) are necessary to obtain soft magnetism, and in order to obtain soft magnetism, it is necessary to set b≧4aL%, and if too much is added, 11s will decrease, so b≦25at.
Must be expressed as %. This M chemically bonds with N contained in the film through heat treatment to produce fine crystals of MN (M nitride). Along with this, the parent phase of Co also exhibits a microcrystalline structure consisting mainly of face-centered cubic elements. Due to the uniform distribution of MN microcrystals in the film, c.

Co crystal grains remain fine even after heat treatment at 550°C. Because Co crystals have large magnetocrystalline anisotropy, soft magnetic properties cannot be obtained with normal-sized crystals, or as the crystals become finer, the effects of magnetocrystalline anisotropy are alleviated, resulting in soft magnetic properties. characteristics are obtained.

N (nitrogen) is necessary to generate MN through a chemical bond with M, thereby increasing heat resistance and increasing Bs. (In the amorphous state, Co and M interact,
While the magnetic moment of Co is considerably suppressed, when M precipitates as MN crystals, M no longer interacts with Co, and the magnetic moment per atom of C+) increases by 2, which increases Bs. . ) Furthermore, N is necessary to increase electrical resistance.

The X-ray diffraction peak of MN microcrystals is observed when C≧20. lat%, and as a result, the magnetostriction approaches zero, and even a single layer exhibits excellent soft magnetic properties. Furthermore, if too much N is added, Bs will decrease, so it is necessary to satisfy C≦35 at %.

The soft magnetic film according to the present invention is manufactured by forming a thin film on the surface of a substrate such as ferrite using a thin film manufacturing apparatus such as a sputtering method or a vacuum evaporation method. As the sputtering device, existing devices such as RF two-pole sputtering, magnetron sputtering, three-pole sputtering, ion beam sputtering, and facing target sputtering can be used. As a target,
In addition to Co-M alloy targets, M on Co target
A composite target with pellets arranged can be used.

Furthermore, in order to obtain a film with better soft magnetic properties, it is effective to apply a magnetic field parallel to the substrate during sputtering, or to apply a magnetic field during heat treatment.

[Example Co 114 T a +o by RP sputtering equipment
A film with a thickness of 5 to 6 μm was produced by sputtering with a mixed gas of Ar+Nt using an alloy target of H[e.

FIG. 1 shows the relationship between N in the sputtering gas, a degree, and the N concentration in the fabricated film.

Figure 2 also shows the relationship between N in the sputtering gas and a degree.
It shows the change in magnetostriction of the film. As is clear from FIG. 2, as the N and A degrees increase (30% by volume or more), the amount of change in magnetostriction due to heat treatment becomes smaller, and both the values after film formation and after heat treatment approach zero. In addition, heat treatment was performed at 550°C
The test was carried out in a rotating magnetic field for 20 minutes.

FIG. 3 shows the change in specific resistance of the film with respect to N in the sputtering gas and a degree. As is clear from FIG. 3, the specific resistance after heat treatment is small at 10 volume % N, but shows a tendency to gradually increase at higher N2 concentrations.

FIG. 4 shows the change in the saturation magnetization (Bs) of the film with respect to the N2 concentration in the sputtering gas. As is clear from Fig. 4, 30 volume% of Bs when 10 volume%N
At N7 or higher, there is a slight tendency to decrease, but even at 50 volume % N, it still has a high Bs of about 1100OG.

Next, a soft magnetic alloy film according to the present invention (hereinafter referred to as an example of the present invention) and a soft magnetic film with a conventional composition (hereinafter referred to as a conventional example) were respectively produced (the compositions of these films are shown in Table 1). .)
Heat treatment was performed in a rotating magnetic field at 550°C for 20 minutes, and soft magnetic properties such as permeability (μ) and coercive force (1-(c)) of these films were compared. The results are shown in Table 2. .

Table 1 * (200 nitrided layers/300 non-nitrided layers) was repeated 120 times for i-lamination.

Table 2 As shown in Table 2, in the examples of the present invention, the magnetostriction and resistivity remained good, μ was high, Ha was low, and good soft magnetic properties were obtained.

On the other hand, among the conventional examples, conventional example 1 containing 17.2 at% N
has good magnetostriction and specific resistance, but is poor because μ is low and T (c is large. Also, composition change, ffA) In conventional example 3, which is made of +i■ structure, μ and T-1c are good. Although the magnetostriction is large and the specific resistance is small in the case of "None", the example of the present invention satisfies all the characteristics even though it is a single layer film.

Incidentally, if the composition modulation film of Conventional Example 3 is made into a single layer nitride film (
(corresponding to Conventional Example 2), the soft magnetic properties are completely poor. From this, it can be seen that even if the example of the present invention is a single layer film, soft magnetic properties superior to those of the conventional soft magnetic film can be obtained.

FIG. 5 shows the results of examining the structure of the film of the present invention by X-ray diffraction. The film of the present invention exhibits one or two broad peaks after film formation (indicated by the symbol ■ in Figure 5), but these peaks can be removed by heat treatment at 550°C, as shown in ■ after the heat treatment. These peaks are relatively sharp for TaN and rccCo (face-centered cubic Co), and also very weakly for hcp-c.

The index is given as (hexagonal dense Co). Also, ■ is a diagram showing the results of X-ray diffraction of the film of Conventional Example 2, and although the film of Conventional Example 2 is amorphous, compared to this,
It can be seen that the film of Example 2 of the present invention is clearly crystalline. That is, the film of the example of the present invention shows that fine crystals of TaN and Co are precipitated. Also, from the half-width of each peak in (■), the diameter of the crystal grains contained in the film of the example of the present invention is 2.
It can be seen that it is extremely small, with 0 to 50 people. This shows that the film of the example of the present invention has excellent soft magnetic properties.

[Effects of the Invention] As explained above, the soft magnetic alloy film according to the present invention has high heat resistance that can sufficiently withstand the glass welding process at around 600°C in the manufacturing of magnetic heads, thereby improving the reliability of glass bonding. You can increase your sexuality. Furthermore, by having a high Bs, it is possible to provide a head that can sufficiently handle high Hc recording media.

Furthermore, in the present invention, magnetostriction can be reduced by increasing the N6 degree without impairing the above characteristics, thereby preventing deterioration of the soft magnetic properties due to stress and strain associated with processing the head. A head having reproducing characteristics can be provided. By increasing the Na content, the electrical resistance of the film increases, which prevents a decrease in high frequency permeability due to eddy current loss at high frequencies, thereby improving the high frequency characteristics of the head.

Furthermore, by increasing the Ng content, it is no longer necessary to have a complex structure such as a multilayer or compositionally modulated structure, and the manufacturing process can be simplified.

[Brief explanation of the drawing]

1 to 5 are diagrams for explaining the present invention in detail, and FIG. 1 is a graph showing the relationship between N concentration in the sputtering gas and N6 degree in the soft magnetic alloy film, and FIG. Figure 2 is a graph showing the change in magnetostriction of the film as a function of the N concentration in the sputtering gas, Figure 3 is a graph showing the change in specific resistance of the film as a function of Nta in the sputtering gas, and Figure 4 is a graph showing the change in the specific resistance of the film as a function of the Nta concentration in the sputtering gas.
FIG. 5 is a graph showing the change in the saturation magnetization of the film with respect to the N2 concentration in the gas, and FIG. 5 is a graph showing the results of X-ray diffraction of the film.

Claims (1)

[Claims] (1) Formula CoaMbNc (where M is Ti, Zr, Hr, Nb, Ta, Mo,
At least one of W, Co represents cobalt, N represents nitrogen, and a, b, and c each represent atomic %), and a, b, and c are 50≦a≦75 4≦b A soft magnetic alloy film having the following composition: ≦25 20.1≦c≦35 a+b+c=100. (2) The soft magnetic alloy film according to claim 1, which contains microcrystals of M nitride and is entirely composed of microcrystals with a grain size of 0.05 μm or less.