JPH02123705A - Heat resistant iron based magnetic film and magnetic head using same - Google Patents

Abstract

PURPOSE:To improve the heat resistance of a magnetic film having a highly saturated magnetic flux density by adding a specified amount of one kind of an element which is selected out of the specified elements in groups IVa, Va and VIa and a specified amount of one kind of an element elected out of B, C and N into a ferromagnetic film whose main component is iron. CONSTITUTION:The following elements are added into a ferromagnetic films whose main component is Fe: 0.1-10atomic% of at least one kind of an element selected among elements of groups IVa, Va and VIa, Ti, Zr, Hf, V, Nb, Ta, Mo and W; and 0.1-1atomic% of at least one kind of an element selected among B, C and N. The heat resistance of an iron based magnetic film wherein Ti, Zr, Hf, V, Nb, Ta, Mo and W, which are elements of groups IVa, Va and VIa, are added is improved without decreasing relative permeability. When the adequate amount of B, C or N is added in the iron based magnetic film, the diameter of the crystal grain in the iron based film is miniaturized, and the relative permeability is increased with the increase in the concentration of the added material. Thus, the magnetic film characterized by a highly saturated magnetic flux density and high heat resistance can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic pole material for a magnetic head used in a magnetic disk drive, a VTR, etc., and in particular has high saturation magnetic flux density, high magnetic permeability, heat resistance, and high corrosion resistance. The present invention relates to a ferromagnetic film and a magnetic head using the same.

[Conventional technology]

In recent years, magnetic recording technology has made remarkable progress, and household VTRs are becoming smaller and lighter, and recording densities are being increased for future digital VTRs. Furthermore, in the field of magnetic disk drives, the recording density is being increased in order to increase the capacity. Such high density requires a magnetic head with a magnetic pole made of a magnetic film with a high saturation magnetic flux density that can sufficiently record signals on a high coercivity recording medium.

In addition to having a high saturation magnetic flux density, the magnetic film constituting the magnetic pole of a magnetic head is required to have a high magnetic permeability in order to improve recording and reproducing efficiency. Also.

It is required to have heat resistance that can withstand the heating process in the process of forming a magnetic head and maintain high magnetic permeability.

Magnetic elements with high saturation magnetic flux density include Fe, a transition metal element,
There are Co, Ni, etc. Since these elements alone have low magnetic permeability, they cannot be used as materials for magnetic heads. Therefore, in the past, efforts have been made to improve the magnetic permeability by adding other elements to Fe, which has a high saturation magnetic flux density, and creating multiple layers. For example, JP-A-62
In No. 281106, Zr, C, etc. were added to Fe to improve the relative magnetic permeability.

[Problem to be solved by the invention]

Although the above-mentioned conventional technology was excellent in terms of improving relative magnetic permeability, it did not take into account the high-temperature process that goes through when forming a magnetic head. In particular, when forming metal-in-gap magnetic heads that require glass bonding, there is a high-temperature process of 500 to 700°C, so high heat resistance does not cause deterioration of relative magnetic permeability even at this high temperature. The development of a magnetic film was required.

Therefore, an object of the present invention is to improve the heat resistance of a magnetic film containing Fe as a main component and having a high saturation magnetic flux density. Another purpose is to improve corrosion resistance.

[Means for Solving Problem 111] In order to achieve the above object, the present invention includes a ferromagnetic film containing Fe as a main component and Ti of IVa, Va, and VIa elements.

B contains at least one element selected from Zr, Hf, V, Nb, Ta, Mo, and W in an amount of 0.1 to 10 at% B.

0.11a of at least one element selected from C and N
t% was added. In addition, in order to achieve the other object mentioned above, Rh or Ru is further added to the above magnetic film.
．． It is added in an amount of 1 to 5 at%.

In order to improve the magnetic permeability of the magnetic film of the present invention, and particularly to prevent deterioration of the magnetic permeability when processed into a magnetic pole shape, it is desirable to stack the magnetic films with a nonmagnetic insulating layer interposed therebetween. Also, to further improve magnetic permeability, use a metal film different from the magnetic film! ! It is also effective to do tM.

[Effect]

The present inventors have been conducting research on a magnetic film whose main component is Fe, which has a high saturation magnetic flux density. Among these, rVa, V
a, Group VIa elements Ti, Zr, and Hf.

It has been revealed that an iron-based magnetic film to which V, Nb, Ta, Mo, and W are added has improved heat resistance without decreasing relative magnetic permeability. I'/ a + V a r VI The reason why the addition of group a elements improves the heat resistance of iron-based magnetic films is not clear, but the inventors believe that these elements have relatively high melting points. Based on this fact, we believe that this is the result of suppressing recrystallization of the crystal grains constituting the iron-based magnetic film at high temperatures and maintaining fine crystals up to high temperatures. The Fs-based magnetic film has a magnetocrystalline anisotropy constant of approximately 50 KJ/r.
Since the value of n' is about two orders of magnitude larger than that of permalloy alloy, when the crystal grains are enlarged by recrystallization, the relative magnetic permeability deteriorates due to the influence of magnetocrystalline anisotropy.

In fact, when the shape of the crystal grains constituting the magnetic film was observed using an electron microscope, it became clear that recrystallization of the crystal grains occurred in the film with degraded relative magnetic permeability.

On the other hand, when B, C, and N are added to the above-mentioned iron-based magnetic film,
It has become clear that the crystal grain size of iron-based magnetic films becomes finer. At this time, the relative magnetic permeability of the iron-based magnetic film showed a tendency to increase as the concentration of B, C, and N added increased. However, B
, C, and H have the effect of increasing the compressive stress in the magnetic film. It is known that films with large compressive stress easily recrystallize when heated, and in fact, in films containing large amounts of B, C, and N, crystal grains expand when the temperature exceeds 300°C, resulting in It was confirmed that a decrease in magnetic permeability occurred. Therefore, B.

It has become clear that the addition of C and N increases the relative magnetic permeability, but deteriorates the heat resistance.

Furthermore, as a result of adding Rh and Ru to the above-mentioned iron-based magnetic film, the results of corrosion resistance evaluation by salt spray test and high-temperature and high-humidity test can be improved without changing the relative magnetic permeability and heat resistance of the iron-based magnetic film. was confirmed.

The added amount of P/a, Va, Via group elements that improve heat resistance exhibits the effect of improving heat resistance at 0.1 at% or more, and as the amount added increases, the heat resistance tends to improve. However, Since the added magnetic flux density of the iron-based magnetic film decreases as the amount of these non-magnetic elements increases, rVa, Va is required to obtain a high-performance magnetic head.

The amount of VIa element added is preferably 10 at% or less. Therefore, Ti, Zr, Hf, V, Nb, Ta.

The amount of addition of at least one element selected from Mo and W is preferably 0.1 to 10 at%.

The amount of B, C, and N added has a very large effect on the improvement of relative magnetic permeability, and addition of 0.1 at % or more is effective. However, since the solid solubility limit of these elements in Fe is extremely small, addition of 1 at % or more causes an increase in compressive stress and deteriorates heat resistance. Therefore, the amount of at least one element selected from B, C, and N is preferably 0.1 to 1 at%.

The amount of Rh and Ru added is 0.1 at% or more, which is effective in improving corrosion resistance. Although Rh and Ru are non-magnetic elements, when they are dissolved in Fe, exchange interactions with Fs occur, and the decrease in the saturation magnetic flux density of the iron-based magnetic film is not large. However, as a result of corrosion resistance experiments, IVa It has become clear that particularly excellent corrosion resistance is exhibited when the addition amount is approximately the same as that of Group VIa elements. Therefore, the amount of Rh and Ru added is preferably 0.1 to 10 at%.

When the magnetic pole of a magnetic head is formed using the above-mentioned iron-based magnetic film, a circulating magnetic domain is generated in the magnetic pole part, and the relative magnetic permeability of the magnetic pole part tends to decrease. Due to the current loss, the magnetic permeability in the high frequency region decreases. Therefore, in order to create a magnetic head with high recording and reproducing efficiency, it is preferable to insert a non-magnetic insulating layer into the iron-based magnetic film to control the magnetic domain structure and prevent eddy current loss. The non-magnetic layer is 100-10
It is already known that eddy current loss can be prevented by inserting 100 to 1000 insulating layers, but in the present invention, by inserting a non-magnetic and insulating intermediate layer, , is characterized by solving both magnetic domain structure control and eddy current loss prevention with one type of intermediate layer.

Thereby, film formation can be simplified.

On the other hand, the relative magnetic permeability of the above-mentioned iron-based magnetic film is at a frequency of 5 M
Hz is 5oO to 1500, but this magnetic film has a second intermediate layer that is different from the first intermediate layer and also different from the magnetic film.
By inserting a metal intermediate layer, the relative permeability can be increased to 150
It can be improved from 0 to 3000. At this time, the insertion of the metal intermediate layer has the effect of refining the crystal grain size of the iron-based magnetic film, and it is sufficient to insert the metal intermediate layer into the iron-based magnetic film at a period of 500 to 2000. Film thickness is 10-100
The person is appropriate. If this intermediate layer is made of a nonmagnetic metal or a metal with a low saturation magnetic flux density, the saturation magnetic flux density of the iron-based magnetic film will decrease as a whole, so it is desirable that the thickness of this intermediate layer be thin.

【Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

(Example 1) A magnetic recording bag [Fa-Ta-R as a magnetic film for a magnetic pole constituting a magnetic head of (a magnetic disk device, a VTR, etc.)
Using a u-C based material, using BN as the first non-magnetic insulating intermediate layer, and using an N1-Fa gold alloy as the second metal intermediate layer,
An iron-based magnetic film was formed. The iron-based magnetic film was formed by the ion beam sputtering method. The ion beam sputtering device used in this example was a dual ion beam device, with two ion guns, one of which sputtered the target and sputtered particles. Deposit on the substrate. In addition, one of the ion guns can directly irradiate the substrate with ions.1 Normally, low acceleration energy (5
The film structure of the deposited film can be controlled by applying ions of 00 V or less to the substrate. In addition, since there is no plasma in the film forming chamber of the ion beam sputtering device, a target exchange mechanism (for example, a mechanism for exchanging multiple targets by rotating them) can be installed, making it easy to form laminated films. be able to. The ion beam sputtering conditions preferred for forming an iron-based magnetic film having high saturation magnetic flux density, high magnetic permeability, high heat resistance, and high corrosion resistance were as follows. First ion gun acceleration voltage 1000
~1400V 2nd ion gun acceleration voltage 200~40
0VAr pressure 2~3 x 10-”
Fe-Ta-Ru-C targets, BN targets, and Ni-20vt%Fe targets mixed in various compositions were alternately sputtered under conditions of a substrate surface temperature of 50 to 100'C and a substrate rotation speed of 20 to 60 RPM or higher. An iron-based magnetic film was formed. At this time, an iron-based magnetic film with a thickness of 0.5 to 2 μm is formed on the ZrOx substrate for the magnetic head pole of the magnetic disk device, and the V
For the magnetic pole of a metal-in-gap magnetic head for TR, an iron-based magnetic film with a thickness of 2 to 5 μm was formed on a ferrite single crystal substrate. The compositions of the various magnetic films obtained as a result were analyzed by plasma emission spectroscopy (solution method) and EPMA (electron probe microanalysis). In addition, the saturation magnetic flux density of these magnetic films can be measured using a vibrating sample magnetometer,
Relative magnetic permeability was measured using a vector impedance meter. Heat resistance was determined by heat-treating the magnetic film by varying the heat treatment temperature and measuring the change in relative magnetic permeability. At this time, the temperature at which the relative magnetic permeability starts to decrease was defined as the heat-resistant temperature. Further, the corrosion resistance of the magnetic film was evaluated by maintaining the temperature at 30° C. while spraying a 1% NaC11 aqueous solution, and determining the number of days the magnetic film was held at the time when the saturation magnetic flux density of the magnetic film decreased to 90% of that at the start of the test.

FIG. 1 shows the structure of the produced iron-based magnetic film.

Thickness of the BN layer of the nonmagnetic insulating layer and Ni-20 of the metal layer
The optimum thickness of the wt%Fa layer varies depending on the total thickness of the iron-based magnetic film, but it is 100 to 1000 and 10 to 100, respectively.
The number was set at 100 people. Note that the magnetic head pole for a magnetic disk device is made of SiO2 on the iron-based magnetic film shown in FIG.
Alternatively, after providing a gap layer made of AQzO++, an iron-based magnetic film similar to that shown in FIG. 1 was formed thereon.

Also, the metal-in-gap head magnetic pole for VTR is the first
A pair of SiO2 cap layers formed on iron-based magnetic films shown in the figure were fixed with the SiO2 facing each other.

It was made by filling the void with glass.

FIG. 2 shows how the saturation magnetic flux density and allowable temperature limit of the iron-based magnetic film having the structure shown in FIG. 1 change depending on T a of 4 degrees in the magnetic film. As can be seen from the figure, the heat resistance temperature increased as the Ta concentration increased, reaching approximately 700° C. at 20 at%. However, the saturation magnetic flux density decreased with Ta concentration, and decreased to about 1.6 T at 20 at%. From this result, the Ta concentration at which the heat resistance temperature is 500℃ or higher and the saturation magnetic flux density is 1.7T or higher is 0.1 to 10at.
%, and within this concentration range it is possible to manufacture a magnetic head with excellent recording and reproducing characteristics.

Note that the above consideration is based on F e -T a -Ru -C@
The Ru concentration was fixed at about 1 at% and the C concentration at about 0.5 at%. The addition of Ru was particularly effective in improving the corrosion resistance of iron-based magnetic films. Ta concentration is 2at
%, the C concentration was fixed at 0.5 at% and the effect of Ru concentration on corrosion resistance was investigated. The results are shown in Figure 3.
The figure shows changes in the saturation magnetic flux density of iron-based magnetic films. The corrosion resistance of iron-based magnetic films improves as Ru11 degrees increases, and
．． It has been revealed that addition of 1 at % or more can withstand a salt spray test of 10 days or more. However, as in the case of adding Ta, as the Ru concentration increases, the saturation magnetic flux density of the iron-based magnetic film decreases, so the amount of Ru added is preferably 10 at % or less. Note that although Ru is a nonmagnetic material, it had less effect in reducing the saturation magnetic flux density than Ta. Furthermore, the effect of adding Ru on the corrosion resistance of the iron-based magnetic film was remarkable in the presence of Ta. Even when Ru was added to an iron-based magnetic film to which Ta was not added, the salt spray test results were not favorable. therefore,
It was confirmed that improvement in corrosion resistance occurs when Ta and Ru coexist. Similar results were obtained for other IVa, Va.

Even when Via group elements are added, [1] and IV
It is clear that the coexistence of a, Va, and Vla elements with Rh and Ru leads to improved corrosion resistance.

The Ta concentration of the Fe-Ta-Ru-C magnetic film is 1
At% and Ru concentration were fixed at 1 at%, C'a degree was varied, and the influence on the relative magnetic permeability and heat resistance temperature of the iron-based magnetic film was investigated. FIG. 4 shows the influence of C concentration on the relative magnetic permeability and heat resistance temperature of the iron-based magnetic film.

As is clear from FIG. 4, as the C concentration increases, the relative magnetic permeability of the iron-based magnetic film tends to increase, but the heat resistance temperature decreases. When the obtained iron-based magnetic film was observed by X-ray diffraction, it was inferred that an increase in the C concentration made the crystal grain size of the iron-based magnetic film finer, and as a result, the relative magnetic permeability increased. It has also been revealed that an increase in C concentration simultaneously increases compressive stress in the film.

It was also confirmed that an increase in compressive stress promotes recrystallization of the crystal grains constituting the magnetic film, leading to a decrease in the heat resistance temperature. As a result, the C concentration in the iron-based magnetic film showed a relative permeability of 1500 or more, and a heat resistance temperature of 500°C or more.
．． It has become clear that 1 to fat% is desirable.

The above-mentioned relative magnetic permeability is a value obtained by measuring the relative magnetic permeability of an iron-based magnetic film formed over a wide area on a substrate.

Furthermore, this iron-based magnetic film was made into a width of 1 by ion milling.
After processing into stripes of 0 μm, relative magnetic permeability was measured. As a result, no significant difference was observed between the relative magnetic permeability of the iron-based magnetic film of this example before and after processing into stripes. On the other hand, a magnetic film was formed by removing the BN nonmagnetic insulating layer from the iron-based magnetic film of this example (see Figure 1), and the relative magnetic permeability before and after processing into stripes was measured. Before, the relative magnetic permeability was almost the same as when a BN non-magnetic insulating layer was present, but after processing into stripes with a width of 10 μm, the relative magnetic permeability decreased to 30 to 60% of the value before processing. Ta. This result is presumed to be based on the fact that the magnetic domain structure and eddy current of the iron-based magnetic film were controlled by the insertion of the non-magnetic insulating layer, and the insertion of the non-magnetic insulating layer is important for maintaining relative magnetic permeability. This is what is shown.

(Example 2) In Example 1, the F a -Ta -Ru -C magnetic layer, the BN nonmagnetic insulating layer, and the Ni-20vt%Ni metal layer were changed to the materials shown in FIG. 5 to form an iron-based magnetic film. The saturation magnetic flux density, relative magnetic permeability, heat resistance temperature, and corrosion resistance days were measured. The results are summarized in FIG. The composition of the magnetic layer is such that the concentration of IVa, Va, and Via group elements is 2 at%, and R
h, the Ru concentration was 1 at%, and the C concentration was 0.5 at%.

As shown in FIG. 5, Ti is added to Fa.

An element selected from Zn, Hf, V, Nb, Ta, Mo, W, an element selected from Rh, Ru, B, N.

An iron-based magnetic film in which a magnetic layer doped with an element selected from C is laminated via a non-magnetic insulating intermediate layer and a metal intermediate layer has a saturation magnetic flux density of 1.8 T or more, a relative magnetic permeability of 1500 or more, and a heat-resistant temperature of 5.
It was confirmed that it exhibits excellent properties, with corrosion resistance of 10 days or more at temperatures above 00°C.

Using the above-mentioned iron-based magnetic film as a magnetic head magnetic pole for a magnetic disk and a metal-in-gap head magnetic pole for a VTR,
As a result of evaluating the recording and reproducing characteristics, the conventional magnetic recording density was 8.
12 above 0KBPI (kilobits per inch)
It was possible to obtain a recording density of 0 KBPI or more.

Although the above examples showed the results of film formation by ion beam sputtering method, the present inventors
A similar study was conducted using the sputtering method, and it was confirmed that substantially similar results could be obtained by raising the substrate temperature to around 150'C. Therefore, the present invention is not limited by the film formation method.

〔Effect of the invention〕

As explained above, the iron-based magnetic film according to the present invention has high saturation magnetic flux density (1.8 T or more), high relative permeability (1500 or more), high heat resistance (500'C or more), and high corrosion resistance (salt spray test 10 It has excellent properties of more than one day). therefore,
When this magnetic film is used as a magnetic head pole for a magnetic recording device, a magnetic recording device with high recording and reproducing characteristics and high reliability can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the cross-sectional structure of an iron-based magnetic film using an example of the present invention, FIG. 2 is a graph showing the influence of Ta concentration on the saturation magnetic flux density and heat resistance temperature of the iron-based magnetic film, and FIG. Figure 3 is a graph showing the influence of Ru concentration on the saturation magnetic flux density and corrosion resistance of iron-based magnetic films. Figure 4 is a graph showing the influence of aS degree on the relative magnetic permeability and heat resistance temperature of iron-based magnetic films. The figure is a table showing the magnetic flux density, relative magnetic permeability, heat resistance temperature, and corrosion resistance days of the iron-based magnetic film of the present invention. 1... Substrate, 2-F a -T a -Ru -C
Magnetic layer, 3... BN nonmagnetic insulating layer, 4... Fa-2
0 wt% Ni metal layer. 1st mouth Fe -20wtE Ni gold 44 2nd Ta branch (oi%) 1st branch ((22%

Claims (5)

[Claims] 1. 0.1 to 10 at% of at least one element selected from the IVa, Va, and VIa elements Ti, Zr, Hf, V, Nb, Ta, Mo, and W to the ferromagnetic film mainly composed of iron, and B.
, C, N at least one element selected from 0.1~
A heat-resistant iron-based magnetic film characterized by adding 1 at%. 2. The ferromagnetic film mainly composed of iron is Rh or Ru.
The heat-resistant iron-based magnetic film according to claim 1, characterized in that it contains 0.1 to 10 at% of. 3. A heat-resistant iron-based magnetic film, characterized in that the heat-resistant iron-based magnetic film according to claim 1 or 2 is laminated with a first intermediate layer made of a non-magnetic insulating layer interposed therebetween. 4. The heat-resistant iron-based magnetic film according to any one of claims 1, 2, and 3 may be used as a second gold layer film.
A heat-resistant iron-based magnetic film characterized in that it is laminated with an intermediate layer of. 5. A magnetic head characterized in that the heat-resistant iron-based magnetic film according to any one of claims 1 to 4 is used as a magnetic pole material of the magnetic recording head.