JPH09134818A - Soft magnetic thin film, magnetic head and magnetic recording device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition allowing compatibility of low inner stress and high-corrosion resistance while maintaining good soft magnetization of a soft-magnetic thin film mainly composed of Fe. SOLUTION: This magnetic film can be expressed by a composition of Fe-X-Y, where X consists of two kinds of elements C and N and satisfies a requirement: C/N=0.5-1.5, Y consists of one kind of elements to be selected from among Cr, Al, Hf, Ta, Nb and Zr, X, Y each have a the concentration of not less than 5at% and not exceeding 25at% besides being in the range of X/Y=0.5 to 1.0 and the rest is Fe. Thereby, a magnetic film, a magnetic head and a magnetic recording device having high performance and high reliability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic thin film, a magnetic head and a magnetic recording device using the same, and more particularly to a microcrystalline precipitation type soft magnetic thin film having good magnetic characteristics and corrosion resistance, and a soft magnetic thin film thereof. The present invention relates to a magnetic head and a magnetic recording device using a magnetic thin film and having high performance and high reliability.

[0002]

2. Description of the Related Art With the progress of advanced information society in recent years, there is an increasing need for a compact and high-density information storage device. Among them, magnetic recording devices have been rapidly researched for high-density recording.

In order to realize high density recording in a magnetic recording apparatus, a magnetic information recording medium having a high coercive force so that recorded fine magnetic domains are stably present, and the magnetic information recording medium having the high coercive force are sufficiently magnetized. Therefore, a high performance magnetic head capable of recording a signal is required. Further, for such a magnetic head, a soft magnetic magnetic material having a high saturation magnetic flux density capable of generating a strong magnetic field is required. Fe-C-based and Fe-N-based soft magnetic materials having a high saturation magnetic flux density that are currently proposed are known.

Since the magnetic material is mainly Fe, it reacts with oxygen and water in the atmosphere to form hydroxides and oxides, which may cause fluctuations in magnetic characteristics, particularly coercive force and saturation magnetic flux density. Occurs. Therefore, the performance of the magnetic head using the magnetic material may deteriorate with time. Therefore,
For example, Japanese Patent Laid-Open No. 3-20444 proposes to add an element that improves corrosion resistance to a magnetic material.

[0005]

In the above-mentioned known examples, addition of an element that improves corrosion resistance may lead to a decrease in saturation magnetic flux density and an increase in magnetostriction constant, so that both good magnetic properties and good corrosion resistance can be obtained. However, there was a problem that could not be secured. That is, if the magnetic characteristics are prioritized, sufficient corrosion resistance cannot be ensured, and the reliability of the magnetic head may decrease. Conversely, if priority is given to corrosion resistance, magnetic characteristics,
In particular, the saturation magnetic flux density and coercive force deteriorate, and the original Fe-C
In some cases, the performance (for example, high saturation magnetic flux density) of the Ni-based or Fe-N-based material cannot be obtained, and the performance of the magnetic head is degraded. Therefore, a first object of the present invention is to provide a soft magnetic thin film that can secure both good magnetic characteristics and good corrosion resistance. Further, the second aspect of the present invention
It is an object of the present invention to provide a magnetic head and a magnetic recording device having high performance and high reliability.

[0006]

The inventors of the present invention have proposed that F
The present invention has been completed as a result of earnest research on a composition capable of ensuring both good magnetic properties and good corrosion resistance in an alloy thin film mainly composed of e. That is, in a first aspect, the present invention is an alloy thin film represented by a structure of Fe-XY, wherein X is composed of two kinds of elements C and N, and a ratio of carbon to nitrogen: C / N. = 0.5 to 1.5, Y is composed of one element selected from Cr, Al, Hf, Ta, Nb, and Zr, and the concentration of X is 5 at% or more and 25 at.
% Or less, the concentration of Y is 5 at% or more and 25 at% or less, X / Y = 0.5 to 1.0, and the balance is Fe. I will provide a. When C / N <0.5, the internal stress was increased, and when a magnetic head was manufactured, there was a problem that peeling from the substrate or cracking occurred. On the other hand, in the case of 1.5 <C / N, the crystal grain size S of Fe was coarsened and the corrosion resistance was deteriorated. Therefore, it has been found that the range of 0.5 ≦ C / N ≦ 1.5 is a composition that balances the internal stress and the corrosion resistance. If the X and Y concentrations are lower than 5 at% or higher than 25 at%, the soft magnetic properties required for the magnetic head (μ ≧ 1000,
Hc ≦ 1Oe) cannot be obtained. Therefore, the X and Y concentrations must be in the range of 5 at% or more and 25 at% or less. If X / Y <0.5 or 1.0 <X / Y, internal stress increases or corrosion resistance deteriorates. Therefore, X / Y =
The range of 0.5 to 1.0 is a composition that balances internal stress and corrosion resistance. Note that it is preferable to perform heat treatment after film formation in order to exhibit soft magnetic characteristics.

According to a second aspect of the present invention, in the soft magnetic thin film having the above structure, Y is Cr, Hf, Ta, Nb, Zr.
A soft magnetic thin film comprising one element selected from the above and two elements of Al. It has been found that good magnetic properties and good corrosion resistance can be ensured even when one element selected from Cr, Hf, Ta, Nb, and Zr and two elements of Al are used as Y. It was This is Cr, Hf, Ta, N
b and Zr form nitrides and carbides and precipitate around the Fe crystal phase to suppress the growth of Fe crystal particles. Al also forms a solid solution in the Fe phase and exhibits corrosion resistance. It is presumed that there is an effect of improving the crystallinity and suppressing the growth of Fe crystal particles.

According to a third aspect, the present invention provides a soft magnetic thin film having the above-mentioned structure, wherein the crystal grain size of Fe is 7 nm or less. When the crystal grain size of Fe is larger than 7 nm, the coercive force becomes too large. Therefore, from the viewpoint of soft magnetic characteristics, the crystal grain size of Fe is preferably 7 nm or less.

According to a fourth aspect, the present invention provides a soft magnetic thin film having the above-mentioned structure, wherein the (110) plane of Fe is preferentially oriented. For example, when the (200) plane of Fe is preferentially oriented, the coercive force becomes too large. Therefore, from the viewpoint of soft magnetic properties, it is preferable that the (110) plane of Fe is preferentially oriented.

According to a fifth aspect of the present invention, in the soft magnetic thin film having the above structure, the coercive force is 1 Oe or less, and
There is provided a soft magnetic thin film having a magnetic permeability of 1000 or more and an internal stress of the film of 1 × 10 ⁸ N / m or less in a compression or tensile direction. From the viewpoint of a magnetic material for a magnetic head, it is preferable that the coercive force is 1 Oe or less, the magnetic permeability is 1000 or more, and the internal stress of the film is 1 × 10 8 N / m or less in the compressive or tensile direction. .

According to a sixth aspect, the present invention provides a soft magnetic thin film having the above-mentioned structure, wherein the crystal structure thereof is polycrystalline. If it is made of a single crystal, the coercive force becomes too large. Therefore, it is preferably polycrystalline.

In a seventh aspect, the present invention provides a soft magnetic thin film having a saturation magnetic flux density of 1.5 T or more in the soft magnetic thin film having the above structure. When the saturation magnetic flux density is 1.5 T or more, a strong magnetic field can be generated when the magnetic head is created, and high density recording becomes possible.

According to an eighth aspect, the present invention provides a magnetic head using the soft magnetic thin film having the above structure. When a magnetic head is produced by using the above-mentioned soft magnetic thin film for the core or a part of the core, good magnetic characteristics and good corrosion resistance can be obtained. Therefore, the magnetic head has high performance and high reliability.

According to a ninth aspect, the present invention provides a magnetic head having the above-mentioned structure, wherein the magnetic head is a metal-in-gap type. The soft magnetic thin film described above is suitable for use in the structure of a metal-in-gap type magnetic head. Therefore,
Most preferably, it is a metal-in-gap type magnetic head.

According to a tenth aspect, the present invention comprises a magnetic head having the above-mentioned structure and a magnetic information recording medium which moves relative to the magnetic head and records information by a magnetic property. A magnetic recording device is provided. Since a strong magnetic field can be generated by using the above magnetic head, information can be recorded by sufficiently magnetizing the magnetic information recording medium having a high coercive force. Therefore, the magnetic recording device is capable of high density recording.

In an eleventh aspect, the present invention provides the magnetic recording device having the above-mentioned configuration, wherein the information is image information or /
And a magnetic recording device characterized by being audio information. Since the image information and / or the audio information has a large amount of information, it is most preferable to record it in the magnetic recording apparatus of the present invention capable of high density recording.

In a twelfth aspect, the present invention provides the magnetic recording device having the above-mentioned structure, wherein the magnetic information recording medium is a magnetic tape or a magnetic disk. When the magnetic information recording medium is a magnetic tape, it is suitable as a VTR device, for example. When the magnetic information recording medium is a magnetic disk, it is suitable as an information recording device for a computer, for example.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited by this.

-Example 1 of soft magnetic thin film A soft magnetic thin film was formed on a single crystal manganese zinc ferrite substrate by a sputtering method. The sputtering target composition was used an alloy target is _{(Fe 78 Ta 12 C 10)} 90 Al 10. Ar / N ₂ mixed gas (mixing ratio: 92/8) was used as the discharge gas. The sputtering conditions are as follows: discharge gas pressure is 6 mTorr, input RF power density is 40
It is 0 W / 150 mmφ. After obtaining a thin film with a thickness of 5 μm,
Heat treatment was performed at 590 ° C. for 30 minutes to obtain a soft magnetic thin film.

The composition of this soft magnetic thin film is (Fe ₇₆ Ta ₁₂
C ₆ N ₆₎ was ₉₅ Al _5. This composition is a magnetic main element (Fe ₇₆ Ta ₁₀ C ₇ N ₇ ) diluted with Al.
Therefore, C / N = 1, Y is Ta, Al, and X concentration is 1
The concentration of 2 at% and Y was 12 at%, and X / Y = 1.0. The magnetic characteristics are as follows: saturation magnetic flux density is 1.55 T, coercive force is 0.15 Oe, and relative permeability is 4000 (5 MH).
z), the magnetostriction constant is 9 × 10 ⁻⁷ , and the specific resistance is 9 × 10 ⁻⁷ Ω.
m. Moreover, the internal stress is 5 × 10 ^{7 in the} compression direction.
It was less than N / m and was almost stress-free (Fig. 1
Ρ1). When the crystal structure was examined by an X-ray diffraction method, it was found that for Fe, the (110) plane (2Θ = 44.5 °)
Was preferentially oriented, and no other plane was observed. Further, the crystal grain size was determined to be 6 nm from the half width of the diffraction peak (see S1 in FIG. 2). In addition, a very broad peak due to TaC or TaN was observed near 2Θ = 35 °. When the crystal grain size was observed by a transmission electron microscope, the crystal grain size of the (110) plane of Fe was 9 nm at the largest.
And the smallest one was 5 nm. The crystal grain size of TaC or TaN was 1 nm to 2 nm.
Next, in order to examine the corrosion resistance, it was immersed in a 0.5 N NaCl aqueous solution for 500 hours, but no deterioration of the saturation magnetization Ms was observed (see A1 in FIG. 3).

-Example 2 of soft magnetic thin film The internal stress ρ, the crystal grain size S of Fe, and the corrosion resistance when C / N was changed other than C / N = 1 were examined.
The corrosion resistance is 50% in a 0.5N NaCl aqueous solution.
Initial saturation magnetization M of saturation magnetization Ms (500h) after soaking for 0 hours
The deterioration rate (%) with respect to s (0) was evaluated. The results are shown in FIGS. As can be seen from FIG. 1, C / N <0.
In No. 5, the internal stress becomes larger than 1 × 10 ⁸ , and when a magnetic head is manufactured, problems such as separation from the substrate occur. On the other hand, as can be seen from FIG. 2, when C / N> 1.5, the crystal grain size S of Fe becomes larger than 9 nm, which causes a problem of deterioration of soft magnetism. Further, as can be seen from FIG. 3, when C / N> 1.5, the corrosion resistance Ms (500
This causes a problem that h) / Ms (0) rapidly deteriorates. From the above results, good magnetic properties and good corrosion resistance were obtained,
Further, it can be seen that the composition range in which the internal stress and the corrosion resistance are balanced is 0.5 ≦ C / N ≦ 1.5.

In the soft magnetic thin film of (Fe ₇₆ Ta ₁₂ C ₆ N ₆ ) ₉₅ Al ₅ , the crystal grain size of Fe is 15 nm.
The larger the coercive force, the more rapidly it increased. But,
When immersed in a 0.5 N NaCl aqueous solution for 200 hours, the saturation magnetization decreased to 85% of the initial value. That is, when the crystal grain size was large, the coercive force increased, but the corrosion resistance deteriorated. When the Fe orientation was the (200) plane, the coercive force increased to 4 Oe and the soft magnetism deteriorated.

-Example of Magnetic Head- Using the above soft magnetic thin film, a metal-in-gap type magnetic head 10 as shown in FIG. 4 was produced as follows. First, a soft magnetic thin film 1 having a composition of (Fe ₇₆ Ta ₁₂ C ₆ N ₆ ) ₉₅ Al ₅ was formed on a single crystal ferrite substrate 2.
Next, as the gap portion 3, Si is formed on the soft magnetic thin film 1.
O ₂ is formed to a film thickness of 200 nm, and Cr is added to the thickness of 10
It was formed to a film thickness of nm. 600 ° C in a nitrogen stream
Then, the head substrate having the same shape was glass-bonded with the low melting point glass 4. The heat treatment temperature is controlled by the temperature in the glass bonding process, and is not limited to 600 ° C. Also,
A bonding layer may be provided between the ferrite substrate 2 and the soft magnetic thin film 1 to improve the adhesiveness between them. In the magnetic head 10 manufactured as described above, peeling did not occur.

-Example of VTR device-Using the magnetic head 10 described above, a VTR as shown in FIG.
The device 100 was produced. The video signal input to the VTR device 100 is transmitted to the magnetic head 10 as a recording signal via the pre-emphasis 101, the FM modulator 102, the recording equalizer 103, the recording amplifier 104 and the switch 105. The magnetic head 10 records a signal on the relatively moving magnetic tape T based on the recording signal. The signal recorded on the magnetic tape T is read by the magnetic head 10 to be a reproduction signal. The reproduced signal includes a switch 105, a reproduction preamplifier 106, a reproduction equalizer 107, a limiter 108, and an FM demodulator 10.
9, low-pass filter 110 and time base collector 1
The video signal is returned via 11 and is output. Here, the relative moving speed is 36 m / s and the data transfer rate is 4
The track width is 6.1 Mbps and the track width is 40 μm.

When high-definition digital information is recorded by the above VTR device 100, the S / N is 40d.
B or more was obtained. Further, the magnetic head 10 was removed and 0.
The sample was dipped in a 5N NaCl aqueous solution for 500 hours and then set again in the VRT device 100 to measure the recording / reproducing characteristics. As a result, no difference was observed in the recording / reproducing characteristics from before the immersion. Also, remove the magnetic head 10,
Fix it on the Peltier element and keep it at 10 ℃,
The sample was left to stand for 2000 hours or more in a high-temperature and high-humidity environment of ℃ and relative humidity of 95%. However, no occurrence of corrosion was observed. Also, when the recording / reproducing characteristics were measured by setting again in the VRT device 100, no deterioration of the recording / reproducing signal was observed.

In addition to the VTR device, the magnetic head 10 may be used in a magnetic tape device using a helical scan.

-Example of Magnetic Disk Device- Using the magnetic head 10 using the above soft magnetic thin film, FIG.
A magnetic disk device 200 as shown in FIG. The digital signal input to the magnetic disk device 200 is transmitted to the magnetic head 10 as a recording signal via the modulation circuit 201, the write amplifier 202 and the head selection circuit 203. The magnetic head 10 records a signal on the rotating magnetic disk D based on the recording signal. The signal recorded on the magnetic disk D is read by the magnetic head 10 to be a reproduction signal. The reproduction signal is the head selection circuit 203 and the read amplifier 20.
4, returned to the digital signal via the identification circuit 205 and the demodulation circuit 206 and output. Even with the above magnetic disk device 200, high performance and high reliability could be obtained.

-Other Examples- In the above examples, the Fe-Ta-CN-Al based soft magnetic thin film was described, but Fe-Hf-C in which Ta is replaced with Hf is used.
The same effect was obtained with the -N-Al system. That is, (F
When a soft magnetic thin film of e ₇₈ Hf ₁₂ C ₅ N ₅ ) ₉₅ Al ₅ was formed, Bs = 1.65T, μ = 4500 (1 MHz),
Hc = 0.15 Oe and magnetostriction λs = 2 × 10 ⁻⁶ .
The internal stress was close to stress-free. As for the corrosion resistance, the saturation magnetization was not deteriorated even when immersed in a 0.5 N NaCl aqueous solution for 500 hours or more. Also, Hf
The same effect was obtained by using Cr, Nb, or Zr instead of. In addition, Fe-Ta-CN system, Fe-Hf-C-
N system, Fe-Cr-C-N system, Fe-Al-C-N system,
The same effect was obtained with Fe—Nb—C—N based and Fe—Zr—C—N based soft magnetic thin films.

-Comparative Example-The Fe-Hf-N-Al system which does not contain C has good corrosion resistance, but has a large internal stress of 4 x 10 ⁸ N / m, which is not preferable. Further, in the Fe-Hf-C-Al system containing no N, although the internal stress is close to stress-free, the corrosion resistance cannot be ensured (saturation magnetic flux density is about 70 when immersed in 0.5N NaCl aqueous solution for 200 hours). %), Which is not preferable.

[0030]

According to the soft magnetic thin film of the present invention, it is possible to achieve both low internal stress and high corrosion resistance while maintaining good soft magnetism. Further, according to the magnetic head and the magnetic recording apparatus of the present invention, high performance (capable of high density recording) and high reliability (long life) can be obtained.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram of internal stress and C / N ratio of a soft magnetic thin film.

FIG. 2 is a characteristic diagram of Fe crystal grain size and C / N ratio of a soft magnetic thin film.

FIG. 3 is a characteristic diagram of corrosion resistance and C / N ratio of a soft magnetic thin film.

FIG. 4 is a structural diagram of an embodiment of a magnetic head of the present invention.

FIG. 5 is a block diagram of a VTR device according to the present invention.

FIG. 6 is a block diagram of a magnetic disk device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Soft magnetic thin film 2 ... Ferrite substrate 3 ... Gap part 4 ... Low melting point glass 10 ... Magnetic head 100 ... VTR device 200 ... Magnetic disk device

Claims (12)

[Claims] 1. An alloy thin film represented by a structure of Fe—X—Y, wherein X is composed of two kinds of elements, C and N,
Carbon-to-nitrogen ratio: C / N = 0.5 to 1.5, Y is one element selected from Cr, Al, Hf, Ta, Nb, and Zr, and the concentration of X is Is 5 at% or more and 25 at% or less, and the Y concentration is 5 at% or more, 25
A soft magnetic thin film, characterized in that it is at% or less, X / Y = 0.5 to 1.0, and the balance is Fe. 2. The soft magnetic thin film according to claim 1, wherein
A soft magnetic thin film, wherein Y is composed of one element selected from Cr, Hf, Ta, Nb, and Zr and two elements of Al. 3. The soft magnetic thin film according to claim 1 or 2, wherein the crystal grain size of Fe is 7 nm or less. 4. The soft magnetic thin film according to any one of claims 1 to 3, wherein the (110) plane of Fe is preferentially oriented. 5. The soft magnetic thin film according to claim 1, which has a coercive force of 1 Oe or less, a magnetic permeability of 1000 or more, and an internal stress of the film in a compressive or tensile direction. The soft magnetic thin film is characterized in that it is 1 × 10 ⁸ N / m or less. 6. The soft magnetic thin film according to claim 1, wherein the soft magnetic thin film has a crystalline structure of polycrystal. 7. The soft magnetic thin film according to claim 1, wherein the saturation magnetic flux density is 1.5 T or more. 8. A magnetic head using the soft magnetic thin film according to claim 1. Description: 9. The magnetic head according to claim 8, wherein
A magnetic head, wherein the magnetic head is a metal-in-gap type. 10. A magnetic head according to claim 8 or 9, and a magnetic information recording medium which moves relative to the magnetic head and records information by a magnetic property. Magnetic recording device. 11. The magnetic recording device according to claim 10, wherein the information is image information and / or audio information. 12. The magnetic recording device according to claim 10 or 11, wherein the magnetic information recording medium is a magnetic tape or a magnetic disk.