JPH09326313A - Soft magnetic thin film, and magnetic head and magnet recorder using soft magnetic thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure good soft magnetic characteristics, and high thermal stability, high resistance to corrosion, and high reliability, by forming a compound with an element of at least one kind selected among Hf, Nb, Zr, Ta, and Al other than Fe and an element of at least one kind selected among C and N. SOLUTION: An Fe-Hf-N magnetic film in which a compound is formed by selecting, for example Hf among Hf, Nb, Zr, Ta and Al and N among C and N other than Fe is manufactured using a reactive sputtering method and using Fe85 Hf15 sintered structure as a target, and further using NH3 as an N fraction and Ar/NH3 (mixing ratio: 92/8) as discharge gas. The manufactured magnetic film is thermally treated at 600 deg.C for 30 minutes. Use of NH3 as the N fraction improves soft magnetic characteristics and further improves resistance to corrosion of a magnetic film. Further, a metal-in gap type head in which the soft magnetic thin film 1 is formed on a single crystal ferrite substrate 2 can be manufactured.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a soft magnetic thin film, and
The present invention relates to a magnetic head and a magnetic recording device manufactured using the 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 of information, a medium having a high coercive force so that recorded fine magnetic domains can exist stably, 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, Fe-C type and Fe-N type materials are known as materials having a high saturation magnetic flux density proposed. 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 temperature (crystallization temperature) required to develop the soft magnetic properties. This temperature depends on the material system used and its composition.

In addition to the above, when a magnetic head using this material is manufactured, particularly when the head is a metal-in-gap (MIG) type head, a glass bonding step is included in the head manufacturing step, so that the temperature is kept constant. The above annealing is necessary. The bonding temperature in that case is determined by the material of the welding glass used. This temperature is determined by the melting temperature of the deposited glass, 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 conversely, at the low temperature, 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, in putting a magnetic head using this material into practical use, fluctuations in magnetic characteristics due to corrosion when the magnetic film is left in an environment of use are suppressed, and fluctuations in magnetic characteristics are suppressed even after a glass bonding process. The problem was to get rid of it.

In order to solve these problems, it has been proposed to add an element for improving corrosion resistance in addition to the magnetic element. In that case, it was difficult to achieve both soft magnetic properties and corrosion resistance. As a publicly known example in which these points are examined, there is JP-A-3-20444.

[0009]

In the above-mentioned known examples, a method effective for improving any one of the soft magnetic characteristics, the thermal stability and the corrosion resistance is disclosed. . However, a method for simultaneously improving these properties has not been sufficiently disclosed.
In particular, it can be said that there is no soft magnetic film having a saturation magnetic flux density of 1.5 T or more.

An object of the present invention is to provide a magnetic film having good soft magnetic properties, high thermal stability and further high reliability.

[0011]

In order to solve the above problems, a soft magnetic film containing Fe as a main component is used.
A compound containing at least one kind of element selected from Hf, Nb, Zr, Ta and Al and composed of at least one kind of element selected from C and N is used.
Further, it is particularly preferable that at least one element selected from Hf, Nb, Zr, Ta and Al and at least one element selected from C and N form a compound.

In the soft magnetic film containing Fe as a main component, at least one element selected from C and N is added to C in CO, CH ₄ , CO ₂ or metal carbonyl. At least one selected compound is decomposed into C component, and N component is NH ₃ , NO, NO ₂
It is particularly effective to solve the problem to decompose at least one compound selected from the above to obtain N content.

This is a soft magnetic film mainly composed of Fe, and C
For adding at least one element selected from the group consisting of N and N, as for C, at least one type of compound selected from CO, CH ₄ , CO ₂ or metal carbonyl is decomposed to form a C component, For minutes, NH ₃ , NO,
This is because by decomposing at least one compound selected from NO ₂ into N content, the compound can be uniformly dispersed in the thin film.

At the same time, in the soft magnetic film, it is preferable that a part of the C component or the N component is present in the Fe phase as an interstitial solid solution. By making a part of the C component or the N component exist in the Fe phase as an interstitial solid solution, the size of the Fe crystal phase is set to 15 nm or less, and selected from Hf, Nb, Zr, Ta and Al. This is because the size of the compound formed with at least one kind of element can be 3 nm or less.

Further, in the soft magnetic film, at least one element selected from C and N is added, and C is at least 1 selected from CO, CH ₄ , CO ₂ or metal carbonyl. One kind of compound is decomposed into C component, and about N part, at least one kind of compound selected from NH ₃ , NO and NO ₂ is decomposed into N part. As a result, the previous component (C component or N component) and H
The size of the compound particles formed with at least one element selected from f, Nb, Zr, Ta, and Al is 3n.
It can be controlled to be m or less. This effect is particularly effective when the saturation magnetic flux density of the soft magnetic film is 1.5 T or more.

By the way, it is most preferable to use the above-mentioned soft magnetic film as a soft magnetic film for a magnetic head. In particular, a metal-in-gap type magnetic head is most suitable as the magnetic head using the soft magnetic thin film.

Furthermore, this magnetic head is most suitable for recording information on a moving information recording medium by using magnetic properties. The information to be recorded is image information or /
And voice information is most preferable. It is most preferable to use a magnetic recording medium layer formed on a tape or a disk as a moving information recording medium.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1) In this example, Fe-Hf was used as the soft magnetic film.
Take up the N film. The magnetic film was manufactured by using the reactive sputtering method. Using a Fe ₈₅ Hf ₁₅ sintered body as a target, Ar / NH ₃ (mixing ratio: 92/8) was used as the discharge gas.

The sputtering conditions are as follows: discharge gas pressure: 5 mTo
rr, input RF power: 400 W, and the thickness of the formed film is 2 μm. This condition is a value determined by the apparatus used for film formation and is not absolute. Here, NH ₃ is used as the N component because the nitrogen component can be uniformly mixed in the magnetic film, and moreover, it reacts actively with respect to the metal.

The magnetic film produced in this manner was treated at 600 ° C.
Was heat-treated for 30 minutes. When the change in the film structure before and after this heat treatment was examined by an X-ray diffraction method, it was nonmagnetic immediately after the film formation and a very broad peak was observed around 2Θ = 44 °. Was found to be amorphous.

On the other hand, when this film is heat-treated, the magnetic characteristics are as follows: saturation magnetic flux density is 1.6 T and magnetic permeability is 4
500 (5 MHz), coercive force of 0.1 Oe, magnetostriction constant of 4 × 10 to ⁷ and specific resistance of 92.5 × 10 to ⁸ Ω · m,
It showed good soft magnetic properties. According to the X-ray diffraction method and the electron diffraction method, the crystal structure has a main peak at the (110) plane of Fe, and in addition to this, crystal grains that are considered to be Hf ₄ N ₃ , Hf ₃ N ₂ or Hf Was observed. The particle size at that time was 6 nm for Fe (110) and Hf-
Particles such as N were 2 nm.

For comparison, the magnetic properties of a magnetic film produced by using N ₂ gas as a nitrogen source were examined.
The saturation magnetic flux density is the same at 1.6T, but the coercive force is 0.3.
Oe was rather large, and the magnetostriction constant increased sharply to 1 × 10 to ⁶ .

As described above, when NH ₃ is used, the coercive force and the magnetostriction constant can be reduced and the soft magnetic characteristics can be improved. This is because the crystal grain size of the magnetic film is N ₂
When NH ₃ is used than when gas is used, Fe and Hf-
This is because the N particles can be made finer. That is, when NH ₃ is used, the Fe (110) plane is 6 nm and Hf-N is 2 nm, whereas when N ₂ gas is used, the Fe (110) plane is Was 8 nm, Hf-N was 4 nm, and both Fe particles and Hf-N particles were coarse.

When this magnetic film was immersed in 0.5N NaClaq, when NH ₃ was used, the saturation magnetic flux density did not deteriorate even after immersion for 2000 hours or more.
_{When 2} gases were used, the saturation magnetic flux density was reduced by about 7%. As described above, by using NH ₃ , not only the soft magnetic characteristics but also the corrosion resistance of the magnetic film can be improved. When the crystal particles were analyzed by a micro auger, it was found that nitrogen was in solid solution in Fe. This makes it possible to improve the corrosion resistance of the Fe crystal phase in addition to making the crystal grains finer.

Using this magnetic film, an MIG (metal in gap) type head was manufactured. The structure is shown in FIG.

The magnetic head was manufactured by forming the soft magnetic thin film 1 on a single crystal ferrite substrate 2. The composition of the magnetic film used here is Fe ₈₀ Hf ₈ N ₁₂ . The gap 3 is formed by the soft magnetic thin film 1 formed on the ferrite substrate 2.
After forming SiO ₂ to a film thickness of 200 nm on top, Cr
Was formed to a film thickness of 10 nm. 6 in a nitrogen stream
Heat treatment was carried out at 00 ° C. for 30 minutes, and head substrates having the same shape were bonded with the low melting point glass 4.

Here, the heat treatment temperature is governed by the physical properties of the glass such as the glass fusion temperature in this glass bonding step, and is not limited to this temperature. Further, a bonding layer may be provided between the substrate and the magnetic film for improving the adhesion between the two. If the underlayer has magnetism, the performance of the magnetic head can be further improved. In the magnetic head manufactured in this way,
No film peeling occurred.

Using this magnetic head, a VTR device was produced and a tape was run to record image information. High-definition digital information recorded, S / N is 40
dB or more was obtained. Here, the relative speed is 36 m / s,
Data transfer rate is 46.1Mbps, track width is 40μ
m.

The corrosion resistance of this head was tested by immersion in a 0.5N aqueous sodium chloride solution and in a high temperature and high humidity environment.
It was evaluated by the condensation test method in (60 ° C., relative humidity: 95%). First, the MIG type head chip was immersed in a 0.5N aqueous sodium chloride solution for 500 hours. afterwards,
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.

The evaluation by the dew condensation test method in a high temperature and high humidity environment (60 ° C., relative humidity: 95%) was conducted according to the above MI.
The G head was fixed on a Peltier device and kept at 10 ° C., and the whole was left in an environment of 60 ° C. and relative humidity: 95%. As a result, dew condensation occurred on the entire head. 200 in this state
After being left in this environment for 0 hours or more, no corrosion was observed and no deterioration in recording characteristics or reproduction signal was observed.

Up to now, the magnetic head for VTR has been described as an example, but the effect of the present invention can be applied to a magnetic disk device or a magnetic tape device using a helical scan.
It does not depend on the device. This effect, NH ₃
Other than that, the same effect can be obtained by using a discharge gas containing NO or NO ₂ . What is important is to evenly disperse the nitrogen in the film.

Example 2 In this example, an Fe-Ta-C film is taken as the soft magnetic film. To make a magnetic film,
The reactive sputtering method was used. The target was a Fe ₈₅ Ta ₁₅ sintered body, and the discharge gas was Ar / CH ₄ (mixing ratio: 9
0/10) were used respectively.

The conditions of sputtering are discharge gas pressure: 5 mTo
rr, input RF power: 400 W, and the thickness of the formed film is 2 μm. This condition is a value determined by the apparatus used for film formation and is not absolute. Here, CH ₄ is used as the C content because the carbon content can be uniformly mixed in the magnetic film, and moreover, it reacts actively with the metal.

The magnetic film produced in this manner was treated at 600 ° C.
Was heat-treated for 30 minutes. When the change in the film structure before and after this heat treatment was examined by an X-ray diffraction method, it was non-magnetic immediately after the film formation, and a very broad peak was observed near 2Θ = 44 °. It was found to be crystalline. On the other hand, when this film is heat-treated, the magnetic properties are as follows: saturation magnetic flux density is 1.6 T, magnetic permeability is 5000 (5 MHz), coercive force is 0.15 Oe, magnetostriction constant is 3 × 10 to ⁷ , resistance is ^{95.5 × 10 ~ 8 Ω · m} , exhibited good soft magnetic properties. The crystal structure is X
According to the line diffraction method and the electron beam diffraction method, Fe (110)
The plane is the main peak, and in addition to this, crystal grains considered to be TaC were observed. At that time, the particle size of Fe (110) was 6 nm, and the particle size of TaC and the like was 2 nm.

For comparison, as a carbon source (Fe ₇₉ Ta
_{When the} magnetic properties of the magnetic film produced by using the target of the composition ₉ C ₁₂ ) ₉₀ Al ₁₀ were examined, the saturation magnetic flux density was the same at 1.5 T, but the coercive force was a little larger than 0.3 Oe and the magnetostriction was large. constant is suddenly increased with 1 × 10 ~ ^6.

In particular, by using CH ₄ , the coercive force and the magnetostriction constant can be reduced and the soft magnetic characteristics can be improved. This is because when the crystal grain size of the magnetic film is CH ₄ , the Fe and TaC grains can be made finer than when the ternary alloy is used. That is, when CH ₄ is used, the Fe (110) plane is 6 nm and TaC is 3 nm, whereas when an alloy target is used, the Fe (110) plane is 8 nm, TaC was 5 nm, and both Fe particles and TaC particles were coarse.

When this magnetic film was immersed in 0.5N NaClaq, no deterioration was observed in the saturation magnetic flux density of the film using CH ₄ even after immersion for 2000 hours or more. On the other hand, in the film using the alloy target, the saturation magnetic flux density decreased by about 7% after being left in this solution for 2000 hours. Thus, by using CH ₄ , not only the soft magnetic characteristics but also the corrosion resistance of the magnetic film can be improved.

Such an effect can be obtained by using a gas such as CO or CO ₂ as a C source source instead of including carbon in the target. Further, even if the C component is added by the metal carbonyl, the same effect can be obtained.

[0039]

According to the present invention, a soft magnetic film having a high saturation magnetic flux density of Bs ≧ 1.5T or more, good soft magnetic properties, high thermal stability and high corrosion resistance can be 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, a magnetic recording medium having a high coercive force can be sufficiently magnetized in various magnetic recording devices such as a VTR device, a magnetic tape device, and a magnetic disk device, so that high density recording can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the structure of a prototype magnetic head.

[Explanation of symbols]

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

Claims (12)

[Claims] 1. In a soft magnetic film containing Fe as a main component, H
A compound containing at least one element selected from f, Nb, Zr, Ta and Al and consisting of at least one element selected from C and N, and
A soft magnetic thin film, characterized in that at least one element selected from Hf, Nb, Zr, Ta and Al and at least one element selected from C and N form a compound. 2. The method according to claim 1, wherein at least one element selected from the above C and N is added, and the C content is at least selected from CO, CH ₄ , CO ₂ and metal carbonyl. A soft magnetic thin film that decomposes one kind of compound and decomposes at least one kind of compound selected from NH ₃ , NO, and NO ₂ for N content. 3. The soft magnetic thin film according to claim 2, wherein the additive is uniformly dispersed in the thin film. 4. The soft magnetic thin film according to claim 1, wherein a part of the C component or the N component is present in the Fe phase as an interstitial solid solution. 5. The size of the Fe crystal phase according to claim 1, 2, 3 or 4, wherein a part of the C component or the N component is present in the Fe phase as an interstitial solid solution.
5 nm or less, Hf, Nb, Zr, Ta, Al
A soft magnetic thin film which forms a compound with at least one element selected from the above, and more advantageously, the size of the compound is 3 nm or less. 6. The method of claim 1, 2, 3, 4, or 5,
To add at least one kind of element selected from C and N, for C, at least one kind of compound selected from CO, CH ₄ , CO ₂ or metal carbonyl is decomposed to obtain a C component, About N minutes, NH ₃ , N
By decomposing at least one kind of compound selected from O and NO ₂ into N content, Hf, Nb, Z
A soft magnetic thin film in which the size of compound particles formed with at least one element selected from r, Ta, and Al is 3 nm or less. 7. A soft magnetic thin film, wherein the soft magnetic film according to claim 1, 2, 3, 4, 5 or 6 has a saturation magnetic flux density of 1.5 T or more. 8. A soft magnetic thin film using the soft magnetic film according to claim 1, 2, 3, 4, 5, 6 or 7 as a soft magnetic film for a magnetic head, and a magnetic head using the same. 9. A magnetic head in which the magnetic head using the soft magnetic thin film according to claim 1, 2, 3, 4, 5, 6, 7 or 8 is a metal-in-gap type magnetic head. 10. A magnetic recording apparatus using the magnetic head according to claim 9 to record information on a moving information recording medium by using magnetic properties. 11. A magnetic recording device according to claim 10, wherein the information to be recorded is image information and / or audio information. 12. A magnetic recording apparatus using the moving information recording medium according to claim 10, wherein a magnetic recording medium layer is formed on a tape or a disk.