JPH09283333A - Soft-magnetic thin film and magnetic head made from soft-magnetic thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a soft-magnetic thin film improved in its soft-magnetic characteristics, heat stability, and corrosion resistance. SOLUTION: This soft-magnetic thin film is mainly made from Fe and contains Ta and/or Hf, and C and/or N, and the plane (110) of Fe is a prioritizes orientation and the size d1 of Fe crystal particle is less than 15nm, and the particle size d2 of Ta-C, Ta-N, Hf-C, or Hf-N is less than 3nm. The size of a crystal particle is controlled by precipitating Fe crystal particle first in the beginning of thin film forming and Ta-C, Ta-N, Hf-C, and Hf-N cystal particle thereafter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcrystalline precipitation type Fe-based soft magnetic thin film having a high saturation magnetic flux density, and particularly to a soft magnetic thin film having high performance and high reliability, and a soft magnetic thin film thereof. The present invention relates to a magnetic head and a magnetic recording device manufactured using a magnetic film.

[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, in magnetic recording devices, researches on high-density recording and downsizing are being rapidly advanced. In order to realize high-density recording, a medium having a high coercive force so that recorded magnetic domains are stably present and a high-performance magnetic head capable of recording on this medium are required. In order to record a signal by sufficiently magnetizing a high coercivity medium, a magnetic head material having a high saturation magnetic flux density capable of generating a strong magnetic field is required.

At present, as a material having a high saturation magnetic flux density which has been proposed, there are Fe-C type and Fe-N type materials. In order to develop soft magnetic properties, these materials are
Heat treatment is performed at a constant temperature. This heat treatment temperature is
It is determined by the crystallization temperature and depends on the material system used and its composition. In addition to this, when a magnetic head is manufactured using this material, particularly when the head is a metal-in-gap (MIG) type head,
Since the head manufacturing process includes a glass bonding process, annealing at a certain temperature or higher is required. The bonding temperature in that case is determined by the melting temperature of the fused glass used, and generally, the bonding temperature is usually higher than the crystallization temperature. This is because when the bonding temperature is high, the strength of the glass is excellent, and when the temperature is low, the glass does not have sufficient strength. For this reason, in the case of a commonly used glass, the temperature is often higher than the temperature at which the soft magnetic characteristics are exhibited. As a result, the magnetic film must have sufficient thermal stability to withstand at least the melting temperature of the glass. In particular, since the soft magnetic characteristics depend on the size of the precipitated fine crystal particles, it is necessary to control the crystal particle size in order to obtain a magnetic film having good soft magnetic characteristics.

Further, since these materials are mainly composed of Fe, they react with oxygen and water in the atmosphere to form hydroxides and oxides, and their magnetic properties, especially coercive force and saturation magnetic flux density Due to the fluctuation, the performance of the magnetic head may be deteriorated. Therefore, when putting a magnetic head using this material into practical use, it is possible to suppress fluctuations in magnetic characteristics due to corrosion when the magnetic film is left in the operating environment, and to prevent fluctuations in magnetic characteristics even after the glass bonding process. The challenge was to prevent it from happening.

In order to solve these problems, it has been proposed to add an element for improving corrosion resistance in addition to the magnetic element, but it has been difficult to achieve both soft magnetic characteristics and corrosion resistance. Japanese Patent Application Laid-Open No. 3-20444 discloses an examination of these points.

[0006]

The above publication discloses a method effective for improving any one of soft magnetic characteristics, thermal stability, and corrosion resistance. However, there is not enough disclosure about how to improve these properties simultaneously. In particular, there is no disclosure of a method for simultaneously improving the above characteristics for a soft magnetic film having a saturation magnetic flux density of 1.5 T or more.

The present invention has been made in view of the above problems of the prior art, and has a soft magnetic thin film having good soft magnetic characteristics, high thermal stability and high reliability. The purpose is to provide.

[0008]

A soft magnetic thin film according to the present invention which can achieve the above object is a soft magnetic thin film mainly composed of Fe, wherein at least one element selected from Ta or Hf and C or Fe crystal grain size d containing at least one element selected from N
₁ and Ta-C, Ta-N, Hf-C, or the ratio d ₁ / d ₂ of the size d ₂ of the Hf-N particles is equal to or more than 5.

A soft magnetic thin film according to the present invention which can achieve the above object is a soft magnetic thin film mainly composed of Fe,
Fe crystal particles containing at least one element selected from Ta or Hf and at least one element selected from C or N, in which the (110) plane of Fe is preferentially oriented. Size d ₁ and Ta-C, Ta-
Ratio d of N, Hf-C, or Hf-N particle size d _2
1 / d ₂ is 5 or less.

The soft magnetic thin film according to the present invention which can achieve the above object is a soft magnetic thin film mainly composed of Fe,
Fe crystal particles containing at least one element selected from Ta or Hf and at least one element selected from C or N, in which the (110) plane of Fe is preferentially oriented. size d ₁ of is at 15nm or less, Ta-C, Ta-N , Hf-C, or the size d ₂ of the Hf-N particles is equal to or is 3nm or less.

The soft magnetic thin film according to the present invention that can achieve the above object is a soft magnetic thin film mainly composed of Fe,
Fe crystal particles containing at least one element selected from Ta or Hf and at least one element selected from C or N, in which the (110) plane of Fe is preferentially oriented. Has a size d ₁ of 15 nm or less, a Ta-C, Ta-N, Hf-C, or Hf-N particle size d ₂ of 3 nm or less, and a ratio d ₁ / d ₂ of 5 or less. Characterize.

To control the crystal grain size of the soft magnetic thin film according to the present invention, Fe crystal grains are deposited at the initial stage of film formation, and then Ta--C, Ta--N, Hf--C, and Hf--N crystal grains are deposited. It can be realized by controlling the growth of crystal grains by precipitation. As described above, in order to secure the magnetic characteristics, heat resistance, and reliability of the magnetic film, the size of the Fe crystal particles and the sizes of the Ta-C, Ta-N, Hf-C, and Hf-N crystal particles are required. It is necessary to keep the ratio of (3) below a certain value and to keep the size of each crystal grain below a certain value. Here, the dimension of the long side of the crystal grain is defined as the size of the crystal grain.

In the present invention, the saturation magnetic flux density of the magnetic film is 1.5.
It is particularly suitable for a magnetic film of T or more. The structure of the magnetic film is Ta-C, Ta-N, H at the crystal grain boundaries of the Fe crystal phase.
Most preferably, it has a structure in which f-C or Hf-N crystal particles are dispersed. Further, it is more preferable that a part of at least one element selected from C or N be solid-solved in the Fe crystal phase. This makes Fe
Since the crystal grains can be made finer and the growth of the crystal grains can be suppressed, the soft magnetic characteristics can be improved, and at the same time, the corrosion resistance and the heat resistance can be improved. In this case, F
The increase in the lattice spacing of e indicates that a part of at least one element selected from C and N is dissolved in the Fe crystal phase.

Further, in the above soft magnetic thin film, Ta
Alternatively, the stoichiometric ratio of at least one element selected from Hf and at least one element selected from N or C is [Hf] (or [Ta]) /
Most preferably, [N] (or [C]) is between 0.50 and 1.5. This is an essential composition range from the viewpoint of magnetic properties and corrosion resistance. In soft magnetic thin film, T
It is possible to control the valence of ions by controlling the stoichiometric ratio of at least one element selected from a or Hf and at least one element selected from N or C. it can.

A metal-in-gap type magnetic head is most suitable as the magnetic head using the soft magnetic thin film. A magnetic recording device using this magnetic head can record and reproduce image information and audio information on a tape-shaped or disk-shaped moving magnetic recording medium.

[0016]

Embodiments of the present invention will be described below. Here, the present invention will be described in detail with reference to the case where a Fe ₇₉ Hf ₁₂ N ₉ alloy film is used as a magnetic film. The magnetic film was produced by the sputtering method. Fe ₈₇ Hf ₁₃ alloy was used as the target, and Ar / was used as the discharge gas.
A mixed gas of N ₂ (volume ratio 92/8) was used. The input RF power density is 400 W / 150 mm ² φ, and the discharge gas pressure is 6 mTorr. However, these conditions are not absolute and depend on the manufacturing apparatus and manufacturing method. The thickness of the formed magnetic film was 5 μm.

The structure of the magnetic film was X-ray amorphous immediately after preparation. This magnetic film was annealed at 600 ° C. for 30 minutes. Annealing was performed in vacuum or in an inert gas such as Ar or N ₂ , and a magnetic field of 10 kOe was externally applied during the heat treatment. When the magnetic characteristics of this film were examined, the saturation magnetic flux density: Bs was 1.6 T and the magnetic permeability: μ was 5000 (5 MH).
z), coercive force: Hc is 0.1 Oe, magnetostriction constant: λs is 2
× 10 ⁻⁷ , and the specific resistance ρ was 95 × 10 ⁻⁸ Ω · m, which was good. Particularly, since the specific resistance is large, the eddy current loss is small, which is suitable for recording and reproducing in a high frequency region. In the structure of this magnetic film, the (110) plane of Fe was the main peak, and the crystal grain size of Fe determined by the Scherrer's formula was 8 nm. In addition to this, an X-ray diffraction peak due to Hf-N was observed. Since the peak is very broad, more accurate measurement than that of Fe is not possible, but the crystal grain size is calculated from this peak to be about 2n.
m. When the size ratio of the above Fe to the crystal particles was obtained, the Fe / Hf-N ratio was 8/2 = 4.

When this film was immersed in 0.5N NaClaq for 1000 hours, no rust was observed,
Moreover, no deterioration of magnetic properties was observed. Further, even if this magnetic film was heat-treated at 700 ° C., no deterioration in magnetic properties or corrosion resistance was observed. Next, various magnetic films having different Fe crystal particle sizes and Hf-N crystal particle sizes are produced by controlling various crystal particle sizes of Fe and TaC by variously selecting sputtering conditions and heat treatment conditions. The relationship between the Fe crystal grain size, the Hf-N crystal grain size, and the corrosion resistance was investigated. The result is shown in FIG. In the figure, white circles (◯) are films in which no rust was found even after immersion in 0.5N NaClaq for 1000 hours, and black circles () are films in which corrosion occurred. The presence or absence of rust was visually determined.

From FIG. 1, the crystal grain size of Fe is 15n.
It can be seen that the corrosion resistance sharply deteriorates when m exceeds m or the Hf-N particle size exceeds 3 nm. On the other hand, when the crystal grain size of Fe is 3 nm or less, on the contrary, the soft magnetic characteristics, especially the coercive force becomes 1 Oe or more, and therefore it cannot be used as a soft magnetic film. Further, a film having an Hf-N crystal grain size of about 1 nm and an Fe crystal grain size of more than 3 nm could not be produced due to the process. The Hf-N crystal grain size has a practical lower limit of about 2 nm. However, a film having a Fe particle size of 2 nm and a Hf-N particle size of 1 nm as observed on a transmission electron microscope level has good corrosion resistance, but has a large coercive force and is unsuitable as a magnetic head material. .

Further, the stoichiometric ratio of Hf and N is not 1: 1, but from the result of lattice image observation using a transmission electron microscope,
Estimating the lattice spacing is Hf ₄ N ₃ . Here, Hf / N = 1.3, but desired magnetic characteristics and corrosion resistance can be obtained within the range of 0.5 to 1.5 even if the stoichiometric ratio is changed. This condition can be realized by changing the nitrogen concentration in the discharge gas during film formation.

The magnetic film in which Hf-N is dispersed in the Fe phase is usually amorphous immediately after the film formation and has a temperature of 500 ° C.
Heat treatment at ~ 600 ° C to separate Fe phase and Hf-N phase,
Precipitate. Then, the Fe / Hf-N crystal grain size ratio is controlled to be 5 or less. In order to further improve the control accuracy, the workability decreases, but if Fe crystal particles are pre-deposited immediately after film formation and the Hf-N phase is deposited by heat treatment at 500 ° C. to 600 ° C., the Fe It is possible to suppress the growth of the crystal particles and at the same time suppress the growth of the Hf-N particles. As a result, the maximum Fe phase is 15n
m, and the Hf-N phase can be suppressed to a maximum of 3 nm, and its accuracy is strong against any of composition fluctuation, sputtering condition fluctuation, and heat treatment condition fluctuation. The added nitrogen forms an interstitial solid solution in the Fe phase in addition to forming a compound with Hf. This can also improve the corrosion resistance of the magnetic film.

The effects described above are not peculiar to Hf-N particles, and in addition to these particles, Hf-C and Ta-
Similar effects can be obtained by dispersing either C or Ta-N. When carbon is used, carbon is present in the Fe phase in the form of an intermetallic compound in addition to the carbide. The difference depending on the material of the compound is that when the electrochemical dissolution potential is measured from the viewpoint of corrosion resistance, it is the highest when Hf-N particles are dispersed, and 0.75 V (Ag / AgCl electrode standard, p
H = 8.3), which has the highest corrosion resistance. Then, Hf-C follows (0.7 V), and Ta-C and Ta-N are low (0.6 V), but both films have sufficient corrosion resistance in practical use.

Using the above magnetic film, MIG (metal
An in-gap type head was produced. FIG. 2 is a schematic view of the manufactured MIG type head. The soft magnetic thin film 1 was formed on a single crystal ferrite substrate 2. The composition of the magnetic film used here is Fe ₈₀ Hf ₈ N ₁₂ . Gap part 3
Was formed by forming SiO ₂ to a film thickness of 200 nm and then forming Cr to a film thickness of 10 nm on the soft magnetic thin film 1 formed on the ferrite substrate 2. This was heat-treated in a nitrogen stream at 600 ° C. for 30 minutes, and head substrates of the same shape were bonded with the low melting point glass 4.

A bonding layer may be provided between the substrate and the magnetic film to improve the adhesiveness between them. This bonding layer is, for example,
_{SiO 2, Si 3 N 4,} Cr 2 O 3, Cr, can be a Fe-Cr or the like. If the underlayer has magnetism, the performance of the magnetic head can be further improved. No film peeling or the like occurred in the magnetic head thus manufactured.

By incorporating this magnetic head in a VTR device,
The tape was run and the image information was recorded. Figure 3 shows the VTR
It is a functional block diagram of an apparatus. The magnetic head 20 shown in FIG. 3 is the MIG type magnetic head of FIG. The magnetic head 20 is displaced by a magnetic head operating mechanism (not shown) at the time of recording / reproducing and brought into contact with the magnetic tape T running at a predetermined speed. The magnetic tape T is driven by a magnetic tape drive system (not shown).

At the time of recording, the input video signal is first sent to the pre-emphasis 31, and then the FM modulator 32,
It is sent to the rotary transformer 35 via the recording equalizer 33 and the recording amplifier 34. Further, it is transmitted from the rotary transformer 35 to the magnetic head 20 and recorded by the magnetic head 20 on the magnetic tape T running in contact with it. During reproduction, the video signal recorded on the magnetic tape T is first read by the magnetic head 20 and then transmitted to the rotary transformer 35. Further, from the rotary transformer 35, a reproduction preamplifier 36, a reproduction equalizer 37, a limiter 38, an FM.
The output video signal is output through the demodulator 39, the low pass filter 40 and the time base collector 41.

When high-definition digital information was recorded by this VTR device, an S / N of 40 dB or more was obtained. Here, the relative speed between the magnetic head 20 and the magnetic tape T is 36 m / s, and the data transfer rate is 46.1 Mb.
The ps and the track width were 40 μm. Next, the corrosion resistance of this magnetic head was evaluated by a dip test method in a 0.5N sodium chloride aqueous solution and a dew condensation test method in a high temperature and high humidity environment (60 ° C., relative humidity: 95%). First,
The MIG type head chip was immersed in a 0.5N sodium chloride aqueous solution for 500 hours. Thereafter, the head was set in the apparatus again, and the recording / reproducing characteristics were measured. As a result, no difference was observed in the recording / reproducing characteristics from before the immersion. Also, high temperature and high humidity environment (60 ℃, relative humidity 95%)
In the evaluation by the dew condensation test method, the MIG head was fixed on the Peltier device and kept at 10 ° C.
It was left in an environment with a relative humidity of 95%. As a result, dew condensation occurred on the entire head. When left in this environment for more than 2000 hours in this state, no corrosion was observed and no deterioration in recording characteristics or reproduction signal was observed.

Although a magnetic head for a VTR has been described here as an example, the magnetic head using the soft magnetic film of the present invention can be applied to a magnetic disk or a magnetic tape device using a helical scan. In addition, here, the Fe-Hf system has been described as an example. However, the effect described here is
-Hf system is not peculiar to La, C in addition to Hf
Similar effects can be obtained by adding elements such as e, Cu, Au, Pb, Ag, and Tl. However, the most effective from all viewpoints of magnetic properties, thermal stability and corrosion resistance,
This is the case when Hf is added. Moreover, since this element does not form a solid solution with Fe in the phase diagram, its effect is greatest. This is followed by La and Ce, followed by Cu, Au, Pb, A
g and Tl are next.

[0029]

According to the present invention, a soft magnetic film having a high saturation magnetic flux density of Bs ≧ 1.5 T or more, good soft magnetic characteristics, high thermal stability and high corrosion resistance is obtained. Obtainable. As a result, a magnetic head having high performance and high reliability and a magnetic recording device using the same can be obtained. In particular, in various magnetic recording devices such as VTR devices, magnetic tape devices, magnetic disk devices, etc., a magnetic recording medium having a high coercive force can be sufficiently magnetized, so that high density recording becomes possible.

[Brief description of drawings]

FIG. 1 Fe crystal grain size and Hf of Fe-based soft magnetic film
The figure which shows the relationship between N crystal grain size and corrosion resistance.

FIG. 2 is a diagram showing a structure of a magnetic head.

FIG. 3 is a functional block diagram of a VTR device.

[Explanation of symbols]

1 ... Soft magnetic thin film, 2 ... Ferrite substrate, 3 ... Gap part, 4 ... Low melting point glass

Claims (16)

[Claims] 1. A soft magnetic thin film containing Fe as a main component,
Fe or Fe containing at least one element selected from Ta or Hf and at least one element selected from C or N, and having Fe crystal grain size d ₁ and Ta−
A soft magnetic thin film characterized in that the ratio d ₁ / d ₂ of the size d ₂ of C, Ta-N, Hf-C or Hf-N particles is 5 or less. 2. In a soft magnetic thin film mainly composed of Fe,
Fe crystal particles containing at least one element selected from Ta or Hf and at least one element selected from C or N, in which the (110) plane of Fe is preferentially oriented. Size d ₁ and Ta-C, Ta-
Ratio d of N, Hf-C, or Hf-N particle size d _2
1 / d ₂ is 5 or less, a soft magnetic thin film. 3. In a soft magnetic thin film mainly composed of Fe,
Fe crystal particles containing at least one element selected from Ta or Hf and at least one element selected from C or N, in which the (110) plane of Fe is preferentially oriented. size d ₁ is at 15nm or less, Ta-C, Ta-N , Hf-C, or soft magnetic thin film characterized in that the size d ₂ of the Hf-N particles is 3nm following. 4. In a soft magnetic thin film mainly composed of Fe,
Fe crystal particles containing at least one element selected from Ta or Hf and at least one element selected from C or N, in which the (110) plane of Fe is preferentially oriented. Has a size d ₁ of 15 nm or less, a Ta-C, Ta-N, Hf-C, or Hf-N particle size d ₂ of 3 nm or less, and a ratio d ₁ / d ₂ of 5 or less. Characteristic soft magnetic thin film. 5. The soft magnetic thin film according to claim 1, wherein a saturation magnetic flux density of the magnetic film is 1.5 T or more. 6. The soft magnetic thin film according to any one of claims 1 to 5, wherein Ta-is present at a crystal grain boundary of a Fe crystal phase.
A soft magnetic thin film in which at least one kind of crystal particles selected from C, Ta-N, Hf-C, and Hf-N is dispersed. 7. The soft magnetic thin film according to claim 1, wherein a part of at least one element selected from C and N is solid-solved in the Fe crystal phase. A soft magnetic thin film characterized in that 8. The soft magnetic thin film according to claim 7,
A soft magnetic thin film characterized in that the lattice spacing of Fe is increased by solid-dissolving at least one kind of element selected from C or N in a crystal phase of Fe. 9. The soft magnetic thin film according to claim 7 or 8, wherein a part of at least one element selected from C and N is dissolved in the Fe crystal phase to form a solid solution of Fe. A soft magnetic thin film having a crystal grain size controlled to 15 nm or less. 10. The soft magnetic thin film according to claim 1, wherein at least one element selected from Ta or Hf and at least one element selected from N or C. Stoichiometric ratio with the element of [Hf]
(Or [Ta]) / [N] (or [C]) = 0.5
A soft magnetic thin film having a thickness of 0 to 1.5. 11. The soft magnetic thin film according to claim 1, wherein at least one element selected from Ta or Hf and at least one element selected from N or C. A soft magnetic thin film characterized in that the valence of ions is controlled by controlling the stoichiometric ratio with the element. 12. A metal-in-made using the soft magnetic thin film according to any one of claims 1 to 11.
Gap type magnetic head. 13. A magnetic recording apparatus comprising the magnetic head according to claim 12 for recording and reproducing information on a moving magnetic recording medium. 14. The magnetic recording device according to claim 13, wherein image information and / or audio information is recorded. 15. The magnetic recording device according to claim 13, wherein the magnetic recording medium has a tape shape or a disk shape. 16. Fe as a main component, at least one element selected from Ta or Hf, and C or N.
Containing at least one element selected from among
In the method for manufacturing a soft magnetic thin film in which the (110) plane of e is preferentially oriented, Fe crystal grains are deposited at the initial stage of film formation, and then Ta-
By precipitating crystal grains of C, Ta-N, Hf-C, and Hf-N, the growth of the crystal grains is controlled, and the size d ₁ of the Fe crystal grains is set to 15 nm or less.
A method for producing a soft magnetic thin film, wherein the size d ₂ of a-N, Hf-C, or Hf-N particles is 3 nm or less.