JPH09326314A - Soft magnetic thin film, magnetic head and magnetic recording device using the same - Google Patents

Abstract

(57) [PROBLEMS] To provide a magnetic film having good soft magnetic properties and at the same time excellent thermal stability and corrosion resistance. SOLUTION: This is a soft magnetic thin film mainly composed of Fe, and contains at least one element selected from at least Nb, Zr, Ta, and Hf, and a nitrogen-containing Fe crystal phase and a nitride crystal phase. A magnetic film containing all or part of its nitrogen component is made of AlN. It may be a soft magnetic thin film containing Fe as a main component, and the thin film is composed of at least Fe and AlN microcrystals. In these soft magnetic thin films, it is preferable that nitrogen is present as an interstitial solid solution and / or a nitride of Fe in the Fe crystal phase present in the thin film.

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, a magnetic head manufactured using the magnetic film, and a magnetic recording device.

[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 coercive force medium, a magnetic head material having a high saturation magnetic flux density capable of generating a strong magnetic field is required. Currently proposed materials having a high saturation magnetic flux density are Fe-C and Fe.
-N system and the like are known. These materials are heat-treated at a certain temperature in order to develop soft magnetic characteristics. The heat treatment temperature is determined by a temperature (crystallization temperature) required to develop soft magnetic characteristics. This temperature depends on the material system used and its composition.

In addition to this, when manufacturing a magnetic head using this material, especially when the head is a metal-in-gap (MIG) type head, a glass bonding step is included in the head manufacturing step, so that a constant temperature is maintained. 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 fused glass.

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 that reason,
In the case of commonly used glass, the temperature is often higher than the temperature at which soft magnetic properties are exhibited. Therefore, the magnetic film must have sufficient thermal stability to withstand at least the melting temperature of 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, particularly 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 have been examined, there is JP-A-3-20444.

[0008]

In the above-mentioned publicly known examples, an effective method is disclosed for improving any one of the soft magnetic characteristics, the thermal stability and the corrosion resistance. . However, a method for simultaneously improving these characteristics 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. Therefore, it has been a problem that no material has been found that can simultaneously satisfy good soft magnetic properties, high thermal stability, and high corrosion resistance.

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

[0010]

The above problem is a soft magnetic thin film mainly composed of Fe, containing at least one element selected from Nb, Zr, Ta and Hf, and nitrogen, and at least a crystal of Fe. This can be solved by using a magnetic film composed of a phase and a crystalline phase of a nitride, and further, all or part of the nitrogen component thereof is composed of AlN. As another material system, a soft magnetic thin film mainly composed of Fe,
The thin film may be a thin film composed of at least Fe and AlN microcrystals. Here, in these soft magnetic thin films, it is preferable that nitrogen is present as an interstitial solid solution and / or a nitride of Fe in the Fe crystal phase present in the thin film. By the way, in making this soft magnetic thin film,
A part of the nitrogen source in the thin film containing N may be supplied by nitrogen gas or material gas. More specifically, in the production of the above-mentioned soft magnetic thin film, one kind of gas selected from ammonia and hydrazine may be contained in the carrier gas as a material gas to be used.

As a result, in the obtained soft magnetic thin film, the crystal grain size of Fe is 15 nm or less, and the crystal grain size of AlN is 5 nm or less, and more preferably,
It is necessary that the crystal grain size of Fe is 10 nm or less and the crystal grain size of AlN is 3 nm or less. By the way, in the production of this soft magnetic thin film, in order to control the crystal grain size of Fe, the Fe crystal phase contains nitrogen and / or AlN grains are dispersed in the thin film to obtain AlN crystal grains. Whether to control the concentration of nitrogen contained in the atmospheric gas during film formation to control the particle size, and /
Alternatively, a sputtering method may be used as a film forming method.

By the way, in the thin film thus produced, Fe is amorphous and / or fine particles immediately after film formation, and crystallized by performing a certain heat treatment, and AlN immediately after film formation. It is preferable that the crystal grain size is 5 nm or less, and that the grain size is constant even if heat treatment is performed. In order to control the crystal grain size of AlN, the nitrogen component concentration in the atmosphere gas at the time of film formation may be controlled. Alternatively, the nitrogen concentration in the film may be controlled. As a result, the obtained soft magnetic film has a saturation magnetic flux density of 1.
Most preferably, it is 5 T or more, the coercive force is 1.0 Oe or less, and the magnetic permeability measured at 1 MHz is 1000 or more.

The above-mentioned soft magnetic film is used as a soft magnetic film for a magnetic head, but a metal-in-gap type magnetic head is most preferable. Further, this magnetic head is most suitable for recording information on a moving information recording medium using magnetic properties. And it is most preferable that the information to be recorded is image information and / or audio information. It is most preferable to use a magnetic recording medium layer formed on a tape or a disk as a moving information recording medium.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described with reference to examples. The sputtering method was used for manufacturing the soft magnetic thin film. A high frequency of about 13.56 MHz or a microwave may be used for excitation. As a target for sputtering, pure Fe was used, and a composite target in which AlN chips were uniformly arranged was used. Al / N ₂ standard mixed gas (mixing ratio: 98/2) was used as the discharge gas. Here, in addition to N ₂ , ammonia or hydrazine may be used as a source source, and these source gases are
It is decomposed by plasma and becomes a nitrogen source. In particular, hydrazine is more effective because it decomposes to generate hydrogen in addition to nitrogen, and oxygen of impurities existing in the atmosphere can be removed. However, considering production, it is advantageous to use nitrogen in terms of ease of handling and price.

The manufacturing conditions are a pressure of 5 mTorr and an input RF.
The power density is 400 W / 150 mmφ. The film thickness is 2μ
m. The structure of the magnetic film thus produced was amorphous in the X-ray at the initial stage of film formation. The magnetic characteristics of this film were that the saturation magnetic flux density was Bs = 0.05T and the coercive force was Hc = 30Oe, which was not suitable for a soft magnetic film for a magnetic head. However, this film was heat treated in a non-oxidizing atmosphere. The temperature is 590 ° C. and the treatment time is 30 minutes. The magnetic characteristics of the film after the heat treatment show that the saturation magnetic flux density is Bs =
The magnetic permeability measured at 1.6 T, coercive force Hc = 0.1 Oe, and 1 MHz is 6500, which is suitable for a soft magnetic film for a magnetic head.

The magnetic film after the above heat treatment is treated with 0.5N NaC.
When the corrosion resistance is evaluated by immersing it in laq,
No corrosion was observed in this soft magnetic film even after immersion for 1000 hours or more, and no change in magnetic characteristics such as saturation magnetic flux density was observed.

When the structure of the magnetic film was analyzed by the X-ray diffraction method, the (110) plane of Fe was preferentially oriented.
The other peaks are very broad and are either fine particles or amorphous. Next, when the structure of this magnetic film was analyzed by a transmission electron microscope, Fe crystal phase and AlN
Phase, Fe having a size of 8 nm, Al
N was 2 nm.

The results of examining the relationship between the size of each crystal grain and the corrosion resistance are shown in FIG. Here, ◯ indicates that the saturation magnetic flux density did not decrease after dipping for 1000 hours or the decrease was 10% or less, and ● indicates that the saturation magnetic flux density decreased more than 10%.

From these results, it is found that the upper limit of the crystal grains is 10n when the Fe phase is 10 nm or less and no corrosion occurs.
In the range of m to 15 nm, the decrease of the saturation magnetic flux density is 10% or less, which is a limit at which practical problems do not occur. Also, Fe
If the crystal grain size of the phase is 2 nm or less, the soft magnetic characteristics and the saturation magnetic flux density are deteriorated, which causes a problem in practical use.

When the AlN particle size was 3 nm or less, the saturation magnetic flux density was not deteriorated and good corrosion resistance was exhibited. However, it is difficult to produce AlN particles of about 1 nm in terms of process. Further, in the range of 3 nm to 5 nm, the decrease of the saturation magnetic flux density is 10% or less, which causes no practical problem. When the thickness exceeds 5 nm, the saturation magnetic flux density deteriorates rapidly.

When a soft magnetic film composed of an Fe crystal phase and an AlN phase and having a size of Fe of 8 nm and AlN of 2 nm was examined by micro Auger spectroscopy and ESCA for the state of nitrogen, it was found that It consists of associative nitrogen. It was revealed from the result of surface analysis by micro-Auger spectroscopy that this binding nitrogen was present in the Fe crystal.

Here, in the film formation, if the Al / N ₂ standard mixed gas is not used, nitrogen does not exist in the Fe crystal, and the crystal grain size cannot be controlled. When the size was 8 nm when manufactured, it became 13 nm and the magnetic characteristics and corrosion resistance deteriorated.
Thus, the solid solution of nitrogen in the Fe crystal could improve the magnetic characteristics and the corrosion resistance.

Using this magnetic film, a MIG (metal in gap) type head was produced. A schematic diagram showing the structure is shown in FIG. To manufacture a magnetic 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 . The gap 3 is formed by forming SiO ₂ to a thickness of 200 nm on the soft magnetic thin film 1 formed on the ferrite substrate 2 and then forming C
r was formed to have a film thickness of 10 nm. 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.

Here, the heat treatment temperature is governed by the physical properties of the glass such as the glass fusing 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. The relative speed is 36 m / s, the data transfer rate is 46.1 Mbps, and the track width is 40 μm.

The corrosion resistance of this head was evaluated by an immersion 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.

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. So far VT
Although the magnetic head for R has been described as an example, the effect of the present invention can be applied to a magnetic disk device or a magnetic tape device using a helical scan, and does not depend on the device or the like.

In the above example, AlN is dispersed in the Fe crystal phase. In addition to this material system, Fe--Hf
An Fe—Hf—AlN system may be used with the alloy as a target. By using this system, nitrogen is solid-dissolved in the Fe crystal phase and AlN is dispersed at the same time, and since Hf is precipitated at the crystal grain boundaries, the particle size control accuracy is further improved, and at the same time, Since the Fe crystal particles become finer, the soft magnetic characteristics and the corrosion resistance can be improved at the same time. The distribution of Fe crystal grain size also becomes smaller,
It is about 6 nm ± 0.5 nm, which can be smaller than 8 nm ± 1 nm of the previous system. This effect is
It can be obtained by using an element such as b, Zr, or Ta, and a plurality of kinds of elements may be combined.

[0030]

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 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, 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 diagram of the relationship between the size of Fe particles and AlN particles and corrosion resistance.

FIG. 2 is an explanatory diagram 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 (14)

[Claims] 1. In a soft magnetic thin film mainly composed of Fe, N
At least one element selected from b, Zr, Ta, and Hf, nitrogen, a crystal phase of Fe, and a crystal phase of a nitride, and all or part of the nitrogen component is AlN. Is a soft magnetic thin film. 2. A soft magnetic thin film mainly composed of Fe, wherein the soft magnetic thin film is a thin film composed of fine crystals of Fe and AlN. 3. The soft magnetic thin film according to claim 1, wherein nitrogen is present as an interstitial solid solution and / or a nitride of Fe in the Fe crystal phase in the thin film. 4. The method for producing a soft magnetic thin film according to claim 1, wherein the source source contains AlN, and a part of the nitrogen source in the thin film is supplied by nitrogen gas or material gas. . 5. The method for manufacturing a soft magnetic thin film according to claim 4, wherein the carrier gas contains one kind of gas selected from ammonia and hydrazine as a material gas to be used. 6. The crystal grain size of Fe is 15 nm or less, the crystal grain size of AlN is 5 nm or less, and the crystal grain size of Fe is 10 nm or less. A soft magnetic thin film having a crystal grain size of 3 nm or less. 7. In order to control the crystal grain size of Fe according to claim 6, nitrogen is included in the Fe crystal phase and / or
Alternatively, the AlN particles are dispersed in a thin film, and the nitrogen concentration contained in the atmosphere gas at the time of film formation is controlled to control the crystal particle size of AlN, and / or the sputtering method is used as the film formation method. The method of manufacturing a soft magnetic thin film by the method. 8. The thin film immediately after film formation according to claim 1, 2, 3 or 6, wherein Fe is amorphous and / or fine particles, and is crystallized by performing a certain heat treatment.
AlN has a crystal grain size of 5 nm or less immediately after film formation,
A soft magnetic thin film whose particle size is constant even after heat treatment. 9. The soft magnetic film according to claim 1, 2, 3, 6 or 8 has a saturation magnetic flux density of 1.5 T or more, a coercive force of 1.0 Oe or less, and a measurement at 1 MHz. A soft magnetic thin film having a magnetic permeability of 1000 or more. 10. A magnetic head using the soft magnetic film according to claim 1, 2, 3, 6, 8 or 9 as a soft magnetic film for a magnetic head. 11. A magnetic head according to claim 10, which is a metal-in-gap type. 12. A magnetic recording apparatus using a magnetic head according to claim 11, as a means for recording information on a moving information recording medium by using magnetic properties. 13. The magnetic recording device according to claim 12, wherein the information to be recorded is image information and / or audio information. 14. A moving information recording medium having a magnetic recording medium layer formed on a tape or a disk is used.
The magnetic recording device according to 1.