JPH0483313A - Soft magnetic thin film and magnetic head - Google Patents

Abstract

PURPOSE:To enable high-saturation flux density, low magnetic distortion, and thermal stability to be improved by allowing a title item to have a main constituent of Fe and to be formed by an iron-group signal-layer alloy with a composition which includes specific atom% of N and Nb. CONSTITUTION:When a soft magnetic thin film is formed by an iron-group signal-layer alloy with a composition which includes 5-16atom% of Fe and 7-14atom% of Nb having Fe as a main constituent, a crystal particle can be thinned in a signal-layer film state, thus achieving a soft magnetic property which is superb in a high saturation flux density and a thermal stability, especially a low magnetic distortion regardless of multilayering of nitride and nonnitride. Also, a soft magnetic alloy thin film in a system which includes 5-16atom% of N and 7-14atom% of Nb with Fe as a main constituent and which includes at least one type of element out of Ta, Ti, and Cr elements by 0.5-6atom% achieves further improved soft magnetic property thermal stability, wear-resistance, and corrosion resistance. Also, a magnetic head which uses this either soft magnetic thin film as a ceramic head core material is highly reliable and attains a high-density recording.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a soft magnetic thin film and a magnetic head used in magnetic heads and the like in magnetic recording and reproducing devices such as magnetic recording and reproducing devices (VTRs) and magnetic recording and reproducing devices. be.

2. Description of the Related Art In response to the recent demand for higher density recording in the field of magnetic recording, development of high-performance magnetic heads compatible with high coercive force media is progressing. The characteristics of a magnetic head are closely related to the material characteristics of the core material used in it, and in order to improve the performance of the magnetic head, we are developing materials with high saturation magnetic flux density, low magnetostriction, and excellent thermal stability. High performance soft magnetic thin films with soft magnetic properties (low coercive force, high magnetic permeability) are required.

``For these requirements, the saturation magnetic flux density of ferrite is approximately 0.5T, permalloy, sendust, and C.

Even with materials made in the northern part of the prefecture, it is as low as around 11, and these conventional materials have a limit to their saturation magnetic flux density.

Therefore, F e-3i/N i-F e, F e-C
/Ni-Fe, Fe/5tot, Fe-Al-N/S
1-N5F e-Nb/F e-Nb-N, etc., have a high saturation magnetic flux density in a multilayer film made by alternately laminating tens to hundreds of different types of magnetic films or ultra-thin non-magnetic films. There has been provided a material that is thermally stable and exhibits good soft magnetic properties. It is believed that the high saturation magnetic flux density and excellent soft magnetic properties of these multilayer films are due to the fine crystal grain structure mainly composed of Fe. In other words, by alternately stacking tens to hundreds of ultra-thin films of different types, the attempt was made to suppress grain growth in the thickness direction of the film and to achieve two-dimensional refinement of crystal grains. .

Problems to be Solved by the Invention However, when using a soft magnetic thin film made of these multilayer films as a magnetic head core material, tens to hundreds of ultra-thin films of different types are alternately laminated to make a total film thickness of several μm. ~several tens of μ
The film-forming process is complicated because it is necessary to form a film with a thickness of 1.5 m, and since each layer is a different type of ultra-thin film, it is difficult to control the film thickness, making it impossible to increase the film-forming speed, making it difficult to mass-produce. There is a problem. In addition, since the soft magnetic thin film is made by alternately laminating different types of ultra-thin films with different magnetic properties, the magnetic properties (saturation magnetic flux density, magnetostriction, coercive force, magnetic permeability) in the thickness direction of the film are non-uniform. The problem arises.

In particular, even if soft magnetic thin films made of these fine grain structures have large thin film magnetostriction, the apparent magnetocrystalline anisotropy decreases, so good soft magnetic properties can be obtained. This causes a problem in that the reproduction output of the magnetic groove is degraded due to the reverse magnetostrictive effect due to external pressure such as when forming a gap in the magnetic groove processing process.

The present invention has been made to solve the above-mentioned problems, and does not rely on multilayering of different types of ultra-thin films, which have problems in mass production and magnetic properties in the film thickness direction, as described above. A soft magnetic thin film made of an iron-based alloy that has three-dimensionally refined crystal grains in a single layer state, and has high saturation magnetic flux density, low magnetostriction, and soft magnetism with excellent thermal stability; The present invention aims to provide a magnetic head using a soft magnetic thin film as a magnetic head core material.

Means for Solving the Problems The present inventor aimed to refine the crystal grains in a single layer state of an Fe-based alloy thin film having a high saturation magnetic flux density, and to achieve high saturation magnetic flux density, low magnetostriction, and thermal stability. We conducted research aimed at developing alloy thin films with excellent soft magnetic properties. If the metal structure of the thin film immediately after deposition is in a crystalline state with grain growth, it is not possible to achieve a fine grain structure of Fe as the main component even if heat treatment is performed, and the state immediately after deposition is an amorphous state. It is necessary to precipitate fine crystal grains by heat treatment.

Generally, it is known that an amorphous alloy is easily formed by rapidly cooling an alloy having a eutectic composition from a temperature just above the eutectic point in an equilibrium phase diagram. Furthermore, it is known that by forming a thin film in Ar--N or a mixed gas, crystal grains tend to become finer.

Therefore, in order to realize a fine grain structure mainly composed of Fe, we focused on a Fe-Nb alloy with a composition near the eutectic point, which has a eutectic point on the high Fe concentration side on the equilibrium phase diagram. When we conducted research on forming thin films in a mixed gas, we found that Fe-N
Even without using a nitrided-non-nitrided multilayer film such as b/Fe-Nb-N, the crystal grains become finer in the single layer state, resulting in a soft film with high saturation magnetic flux density and excellent thermal stability. The inventor discovered the fact that it exhibits magnetic properties (low coercive force, high magnetic permeability), especially low magnetostriction, leading to the invention of claim (1).

In addition, the main component is Fe, contains N, Nb, and Ti.
It is said that a soft magnetic alloy thin film containing at least one of the following elements: , Ta, and Cr has superior thermal stability of soft magnetic properties, as well as superior wear resistance and corrosion resistance, especially in the composition range. We discovered the facts and came up with the invention of claim (2).

The magnetic head according to the invention of claim (3) has high reliability (
In order to achieve high-density recording, the soft magnetic thin film of the present invention, which has high saturation magnetic flux density, low magnetostriction, and excellent soft magnetic properties, as well as excellent corrosion resistance and wear resistance, is used as a magnetic head core material. be.

According to the structure of the invention of function claim (1), A--A
r-N, F of a specific composition range thinned in a mixed gas
Since it is a soft magnetic alloy thin film containing the elements e, Nb, and N, it has a fine grain structure mainly composed of Fe, and has excellent soft magnetic properties, thermal stability, high saturation magnetic flux density, and especially, It has low magnetostriction as well as excellent wear resistance and corrosion resistance. Further, according to the structure of the invention of claim (2), Fe is the main component, N and Nb are included, and Ti, T
Since it is a soft magnetic alloy thin film with a specific composition range of a system containing at least one element of the Cr element, it has excellent thermal stability of soft magnetic properties and also has excellent wear resistance and corrosion resistance. I can do it.

According to the structure of the invention of claim (3), the soft magnetic thin film has high saturation magnetic flux density, low magnetostriction, and soft magnetic properties with excellent thermal stability, and also has excellent wear resistance and corrosion resistance. Since the magnetic head is used as a head core material, high-density recording can be achieved with a highly reliable magnetic head.

Examples Example 1 Using a FeNb alloy target with a composition range of 83 to 95 at% Fe and 5 to 17 at% Nb, N2 gas was introduced into Ar gas, the total pressure was 12 mTorr, and the Nt partial pressure and total pressure ratio P Ht/ A soft magnetic thin film with a film thickness of 2 μm was formed on a water-cooled substrate by high frequency reactive sputtering at P yot-t ) 2.5% and input power of 400 W. The compositional analysis of the film was performed by Ragford backscattering spectroscopy (hereinafter referred to as
Film composition: Fe77 at%, Nb1O at%, N13 at%
etc. are shown as F e 77N b toN 13)
.

These soft magnetic thin films were heated at 500''C in a rotating magnetic field of 5000e in a vacuum below 5Xl0-'Torr.
Heat treatment was performed at a temperature of 1 hour. Coercive force Hc and effective magnetic permeability μ at IMHz of these soft magnetic thin films. , saturation magnetic flux density Bs, and saturation magnetostriction λS were measured.

The results are shown in Table 1. As shown in Table 1, the soft magnetic properties of the film exhibit good properties (low coercive force Fe1 high effective magnetic permeability μ) when the Nb content is in the range of 7 to 14 atomic % near the eutectic point composition. In particular, the best soft magnetic properties are exhibited when the Nb content is 10 at %. The saturation magnetostriction λS shows a low value of 1X10-' or less in the Nb content range of 7 to 14 atomic%, and shows a large λS value at a Nb content of 4 atomic%. The saturation magnetic flux density Bs shows a tendency to decrease as the Nb content increases, and shows a value as high as 1.5 T even when the Nb content is 14 at%.

Therefore, it was found that the Nb content in the film exhibiting excellent soft magnetic properties, low magnetostriction, and high saturation magnetic flux density was in the range of 7 to 14 at.%.

Table 1 Next, by the same reactive sputtering method, Fe of eutectic composition was
Using a toN b lz alloy target, a FeNbN alloy film with a thickness of 2 μm was formed at a N2 partial pressure to total pressure ratio in the range of 0 to 5%. These soft magnetic thin films were heated to 5×10-'Tor.
In a vacuum below r, in a rotating magnetic field of 5000e,
Heat treatment was performed at a temperature of 500° C. for 1 hour, and the coercive force Hc, saturation magnetic flux density Bs, and saturation magnetostriction λS of these soft magnetic thin films were measured. The relationship between the N2 partial pressure to total pressure ratio and the coercive force Hc is shown in FIG.

The coercive force Hc has a minimum value of 0.0 at a N2 partial pressure to total pressure ratio of 2.5%.
30e, and exhibits a low coercive force below loe in the range of 1.7% to 3.5%. N2 partial pressure to total pressure ratio and saturation magnetic flux density B
The relationship between s is shown in FIG. The saturation magnetic flux density Bs shows a maximum value of 1.7T at a N2 partial pressure to total pressure ratio of 2.5%, and shows a value as high as 1.3T even at 5%. Next, FIG. 3 shows the relationship between the N2 partial pressure to total pressure ratio and the saturation magnetostriction λS. The saturation magnetostriction λS is N2
I Xl0-' in the range of partial pressure to total pressure ratio 1.7 to 3.5%
It exhibits low magnetostriction of:

Therefore, it was found that the N2 partial pressure to total pressure ratio, which exhibits excellent soft magnetic properties, low magnetostriction, and high saturation magnetic flux density, is in the range of 1.7 to 3.5%.

Next, it can be seen that the relationship between the N2 partial pressure to total pressure ratio and the nitrogen content in the film is a linear relationship, as shown in FIG. Therefore, it was found that the N content in the film exhibiting excellent soft magnetic properties, low magnetostriction, and high saturation magnetic flux density was in the range of 5 to 16 at.%.

Figure 5 shows Fe after heat treatment, which showed the best magnetic properties.
The measurement results of X-ray diffraction (Cu- and alpha rays) of a 2.7NblON13 alloy film are shown. From the figure, it can be seen that the film structure is a fine crystal grain structure of α-Fe.

When calculating the grain size from the Debye-Scherrer equation, it is approximately 3
There were 0 fine crystal grains. For comparison, the X
The measurement results of line diffraction (Cu- and alpha rays) are shown in FIG. When calculating the crystal grain size from the Debye-Scherrer equation, it is approximately 10
It had gradually grown to 0 people.

In addition, FewzN b
+. Created a T a a N 13 alloy film to improve corrosion resistance,
When we investigated the heat treatment temperature dependence of wear resistance and soft magnetic properties, we found that FettNb+. It was found that it had even better wear resistance and thermal stability than the N1ff alloy film. In addition, in this example, Fe7:INb+eT
a 4 Although the NIs alloy film has been described, it is mainly composed of Fe other than those mentioned above, contains 5 to 16 at.% of Nb, and 7 to 14 at.% of Nb, and also contains one or more of Ta, Ti, and Cr elements. A soft magnetic thin film made of an iron-based single-layer alloy having a composition containing 0.5 to 6 atomic percent of ions has a similar effect. Furthermore, the sputtering method is not limited to the reactive sputtering method in which N2 gas is mixed into Ar gas, but also the sputtering method using nitride as a target, bipolar sputtering, triode sputtering, and magnetron sputtering using direct current or high frequency. Similar effects can be obtained in the method, bias sputtering method, and ion beam sputtering method. Furthermore, similar effects can be obtained in electron beam evaporation, cluster ion beam, and MBE methods other than the sputtering method.

Embodiment 2 As shown in FIG. 7, a magnetic head (MIG head) has a structure in which most of the magnetic path is made of ferrite, and a soft magnetic thin film 3 is provided only in the vicinity of the gear 2, which is likely to be magnetically saturated. The MIG head was fabricated using the soft magnetic thin film made of an iron-based single layer alloy with a saturation magnetic flux density of 166T prepared in Example 1 for the soft magnetic thin film 3 portion. The thickness (M in FIG. 7) of each soft magnetic thin film made of the iron-based single layer alloy was 5 μm, and the gap length was 0.15 μm.
The track width was 5 μm, the gap depth was 20 μm, and the number of turns of the coil was 22 turns. Also, for comparison, the saturation magnetic flux density is 1. A MIG head with the same structure as above was fabricated using the IT sendust film as the soft magnetic thin film 3 portion, and Co-
Cr single layer medium (thickness 0.2 μm, Hc (±) = 1300
The recording and reproducing characteristics at 0eSHk=5KOe) were investigated. This was done by self-recording and replay at a circumferential speed of 3m/see. As a result, a magnetic head using the soft magnetic thin film made of the iron-based single-layer alloy of the present invention as the magnetic head core material has an output increase of about 3 dB compared to a magnetic head using the Sendust film as the magnetic head core material. Ta.

Effects of the Invention According to the invention of claim (1), it has excellent thermally stable soft magnetic properties and high saturation magnetic flux density, especially low magnetostriction, and
A soft magnetic thin film having both excellent wear resistance and corrosion resistance can be provided, and a magnetic head using the soft magnetic thin film of the present invention can be used, for example, in a high-quality VTR that slides at a high relative speed with a magnetic recording medium. suitable.

According to the invention of claim (2), it has soft magnetic properties with even better thermal stability than the soft magnetic thin film according to the invention of claim (1), and also has even better wear resistance and corrosion resistance. It is possible to provide a soft magnetic thin film having both of the following.

According to the invention of claim (3), it has soft magnetic properties with high saturation magnetic flux density, low magnetostriction, and excellent thermal stability, and
Since the magnetic head uses a soft magnetic thin film having excellent wear resistance and corrosion resistance as the magnetic head core material, high-density recording can be achieved with a magnetic head with high reliability.

[Brief explanation of the drawing]

Figure 1 shows the N2 soft magnetic thin film produced in one embodiment of the present invention.
A diagram showing the relationship between partial pressure to total pressure ratio and coercive force Hc, Figure 2 is N
2 is a diagram showing the relationship between the partial pressure to total pressure ratio and the saturation magnetic flux density BS, Figure 3 is a diagram showing the relationship between the N2 partial pressure to total pressure ratio and saturation magnetostriction λS, and Figure 4 is the diagram showing the relationship between the Nz partial pressure to total pressure ratio and the saturation magnetic flux density BS. FIG. 5 and FIG. 6 are X-ray diffraction diagrams, and FIG. 7 is a schematic diagram of a magnetic head. 1... Ferrite, 2... Gap,
3...Soft magnetic thin film, 4...Glass. Agent's name: Patent attorney Shigetaka Awano One idiot's plan is for the people of Aobun. ) Figure 2 3! 9Tt-/ Total H ('/,) Fig. Nitrogen Min/Reference (χ→ Sec.

Claims (3)

[Claims] (1) Fe is the main component, N is 5 to 16 at%, and Nb is 7
A soft magnetic thin film made of an iron-based single layer alloy, characterized in that it has a composition containing ~14 at.%. (2) Fe is the main component, N is 5 to 16 atomic%, and Nb is 7
1. A soft magnetic thin film made of an iron-based single-layer alloy, characterized by having a composition containing ~14 at.% and 0.5-6 at.% of at least one of Ta, Ti, and Cr elements. (3) A magnetic head characterized in that the soft magnetic thin film according to any one of claims (1) and (2) is used as a magnetic head core material.