JPH04252006A - Corrosion-resistant magnetically soft film and magnetic head using the same - Google Patents

Abstract

PURPOSE:To enhance a magnetically soft characteristic and to prevent that a substrate or a filling glass is reacted when a magnetic head is manufactured by using a specific corrosion-resistant magnetically soft film as a core for the magnetic head at a magnetic recording apparatus. CONSTITUTION:Cr or Cr and Mo or W are made to exist in a ferromagnetic metal film which simultaneously contains elements selected from Ti, Zr, Hf, V, Nb, Ta, Mo and W and elements selected from B, C, N and O. The magnetic pole of a metal in-gap tape head is manufactured by using the ferromagnetic film. A magnetic core to which a ferromagnetic film 2 having a film thickness of 5mum has been applied is brought face to face with an Mn-Zn ferrite substrate 1; a gap 4 is formed. The length of the gap is at 0.2mum, and a coil 5 is wound on the magnetic core. A glass bonding temperature is set at 520 deg.C when a head is formed; a reaction layer is not formed when the interface between the magnetic film and a filling glass 3 is observed by using an optical microscope.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to magnetic disk devices, VT
The present invention relates to a magnetic head material used for R, etc., and particularly to a ferromagnetic metal film having high saturation magnetic flux density, high magnetic permeability, high heat resistance, high corrosion resistance, and high reaction resistance, and a magnetic head using the same.

0002

2. Description of the Related Art In recent years, magnetic recording technology has made remarkable progress, and recording density has been improved. In order to increase the recording density, it is necessary to use a recording medium with a high coercive force, and in order to magnetize a recording medium with a high coercive force, a magnetic pole material having a high saturation magnetic flux density is required. For this reason, Ni--Fe alloy (permalloy) and Co-based amorphous alloy thin films are used as magnetic pole materials instead of conventional ferrite. Furthermore, in addition to having a high saturation magnetic flux density, the magnetic pole material is required to have a high magnetic permeability in order to improve recording and reproducing efficiency. Heat resistance is also required because it is necessary to withstand the heating process of glass filling in the process of forming a magnetic head and maintain high magnetic permeability.

[0003] As such a magnetic pole material, Japanese Patent Application Laid-Open No. 1986-
As shown in No. 210607, Fe, Co, N
Nb, Zr, Ti, Ta,
Materials in which Hf, Cr, W, Mo and nitrogen are added simultaneously have been reported. The method for producing this material is to sputter a metal target having a predetermined composition using a mixed gas of argon and nitrogen as a sputtering gas. According to this report, by modulating the nitrogen concentration in the sputtering gas and alternately stacking nitrided and non-nitrided layers, a film with a saturation magnetic flux density of 1.5 T and a coercive force of 1 Oe or less can be obtained. . The coercive force of this film is 60
The temperature was kept as low as 0°C, and the heat resistance was 600°C.

[0004] Also, the Institute of Electronics, Information and Communication Engineers MR89-12 (
1989.7), by simultaneously adding Ti, Zr, Hf, and C to Fe, an Fe-based amorphous film was formed, and this was then heat-treated to create a microcrystalline soft magnetic material with high heat resistance. was shown to be obtained.

[0005]

[Problems to be Solved by the Invention] The present inventors have discovered that Fe-N
b, Fe-Ta, and Fe-Hf based materials were sputtered in a mixed gas of argon and nitrogen, and a supplementary experiment to the above-mentioned report was conducted. As a result, the coercive force was 40 as reported.
It was confirmed that even when heat was applied at 0 to 600°C, a low value of 1 Oe or less was exhibited. In addition, after sputtering Fe-Hf-C based material in argon gas,
It was also confirmed that a ferromagnetic film with a coercive force of 1 Oe or less could be obtained by heat treatment.

However, when the present inventors fabricated these conventional materials on an Mn-Zn ferrite single crystal substrate and subjected them to a heating process at 600°C for glass filling to fabricate a metal-in-gap type head, they found that Mn It was revealed that the -Zn ferrite single crystal substrate and the magnetic film reacted to form an oxide layer at the interface. At this time, as a result of examining the recording and reproducing characteristics of the magnetic head, as expected, a large pseudogap signal was observed due to the nonmagnetic layer at the interface between the crystal substrate and the magnetic film. If such a pseudo gap signal is observed, normal recording and reproduction cannot be performed. At this time, a reaction between the magnetic film and the filled glass was also observed, and it was found that the magnetic film had become thinner. That is,
Conventional magnetic films exhibit excellent soft magnetic properties as a single magnetic film, but when manufacturing magnetic heads that involve a glass bonding process, it has been confirmed that preventing reactions with the substrate or filled glass becomes a problem. .

On the other hand, when a sample formed on a glass substrate as a dummy sample was subjected to a salt spray test and a constant temperature and humidity test to evaluate its corrosion resistance, it was found that the previously used sendust film and Co-Nb-Zr film were In comparison, it corrodes extremely easily, and its use as a magnetic head was questioned.

Accordingly, an object of the present invention is to provide a new magnetic head material that overcomes the above-mentioned drawbacks of the prior art.

[0009]

[Means for Solving the Problems] The present inventors have continued intensive research in order to solve the above-mentioned problems.
Cr in a ferromagnetic metal film containing at least one element selected from Zr, Hf, V, Nb, Ta, Mo, and W and at least one element selected from B, C, N, and O. , or by having Mo or W present at the same time as Cr, it not only has excellent soft magnetic properties and maintains saturation magnetic flux density and soft magnetic properties up to high temperatures, but also has resistance to reactions with oxides such as ferrite and glass. We were able to develop a magnetic head material with high corrosion resistance and high corrosion resistance.

By using the corrosion-resistant soft magnetic film of the present invention in the core of a magnetic head of a magnetic recording device, a magnetic recording device with excellent recording and reproducing characteristics can be obtained. In particular, even greater effects can be obtained by applying the ferromagnetic film of the present invention to a head fabricated by a method including a glass bonding process, such as a metal-in-gap type head.

[0011]

[Operation] As mentioned above, Ti, Zr, Hf, V, Nb,
Cr or Cr in a ferromagnetic metal film containing at least one element selected from Ta, Mo, and W and at least one element selected from B, C, N, and O.
At the same time, by allowing Mo or W to exist, a soft magnetic material that maintains soft magnetic properties even at high temperatures and has high corrosion resistance has been obtained, but the mechanism thereof is not necessarily fully clarified. However, as a result of studies conducted by the present inventors, the crystal grains of the ferromagnetic film containing Cr, Mo, and W are finer than those of the ferromagnetic film that does not contain these, and the dispersion of magnetic anisotropy is reduced. It was confirmed that the soft magnetic properties were improved. It was also confirmed that these additives hardly changed the magnetostriction constant of the ferromagnetic film.
It has become clear that the magnetostriction constant of the above ferromagnetic film can be easily controlled.

The ferromagnetic film mixed with these additives has 60
Even when heated to 0°C, there was almost no coarsening of the crystal grain size, indicating that the additive suppresses the diffusion of the constituent elements of the ferromagnetic film and prevents the crystal grains from growing due to heating. confirmed. In ferromagnetic materials with large magnetocrystalline anisotropy constants such as Fe and Co, the soft magnetic properties are related to the size of the crystal grains that make up the ferromagnetic material, and the soft magnetic properties deteriorate as the crystal grains increase. It is known. Therefore, it is considered that in the ferromagnetic film of the present invention, the crystal grains were kept small even at high temperatures, so that the soft magnetic properties did not deteriorate. At this time, the Institute of Electronics, Information and Communication Engineers MR89-12 (1989
．． According to 7), elements such as Ti, Zr, and Hf have a strong affinity with C, so they easily form carbides of Ti, Zr, and Hf by heat treatment at 450°C or higher, and these carbides combine with Fe. It is presumed that Fe precipitates at the grain boundaries of the ferromagnetic film containing Fe as the main component and suppresses the growth of crystal grains containing Fe as the main component.

The present inventors also use Ti, Zr, Hf, V, Nb
, Ta, Mo, W, etc. and B, N, O by heat treatment at high temperature.
As in the case of Zr, Hf and C, in this case also Ti, Zr
, Hf, V, Nb, Ta, Mo, and W have a strong affinity with B, N, and O, and borides, nitrides, and oxides of these metals have been identified by XPS (X-ray photoelectron spectroscopy) analysis. was confirmed to be formed. Therefore, Ti, Zr, Hf, V, Nb, Ta, M
The reason why Fe and Co added with O, W, etc. and B, N, and O exhibit soft magnetic properties even at high temperatures is because borides, nitrides, and oxides precipitate at the grain boundaries, making Fe and Co the main components. This is thought to be due to the suppression of grain growth in the ferromagnetic film. However, when the same film was examined by X-ray diffraction, the peaks for borides, nitrides, and oxides were not very clear, indicating that these substances were either in trace amounts or were amorphous. . However, when the heat treatment temperature was 600° C. or higher, the X-ray diffraction peaks of these substances became clear, and the presence of borides, nitrides, and oxides was confirmed. These films also contain Cr, Mo,
The ferromagnetic film containing W had finer crystal grains than the ferromagnetic film not containing W, and it was confirmed that the soft magnetic properties were improved. As a result, a ferromagnetic film mainly composed of Fe and Co is coated with IVa, Va, and VIa group elements such as Ti and Zr.
, Hf, V, Nb, Ta, Mo, W at 0.5 to 15 at%, B, C
, N, and O.
A preferable soft magnetic material could be obtained by adding 5 to 15 at% and further adding 0.1 to 10 at% of Cr or the like.

In addition, the saturation magnetic flux density of the ferromagnetic film of the present invention showed a tendency to decrease as the amount of non-magnetic additive increases, but this is due to the effect of simple dilution of the magnetic material by the addition of non-magnetic material. It is assumed that this is due to the following.

[0015]

[Examples] Examples of the present invention will be given below, and will be explained in more detail with reference to figures and tables. [Example 1] A ferromagnetic film containing Fe and Co as main components was formed on a crystallized glass substrate using an RF sputtering device. The target of the sputtering apparatus used in this example is a composite target in which chips of additive elements are attached to a Fe, Co plate. Sputtering was performed under the following conditions.

Sputtering gas...Ar, Ar+N2, Ar+CH3,
Ar+O2 Gas pressure inside the device: 0.5 Pa High frequency power: 400 W Distance between target and substrate: 50 mm Substrate temperature: 100 to 200°C (water cooling) In this example, a crystal with a diameter of 10 mm was used as the substrate. Films of various compositions having a film thickness of 2 μm were formed as shown in Table 1 using a chemically modified glass substrate. The obtained magnetic film showed A in the range of 200°C to 700°C.
Heat treatment was performed in r gas for 1 hour, and each film was evaluated for soft magnetic properties, crystallographic evaluation by X-ray diffraction, compositional analysis by EPMA, and corrosion resistance evaluation by constant temperature and humidity test.

Table 1 shows some of the results, including coercive force and corrosion resistance days.

[0018]

[Table 1]

In the table, the composition of the ferromagnetic metal film is determined by the EPMA method. In addition, coercive force and corrosion resistance tests were conducted at 550℃.
This value was measured after heat treatment for 1 hour. Note that the coercive force was measured using a B-H curve tracer. The number of days of corrosion resistance was determined by a constant temperature and humidity test at 80° C. and 90% humidity, and was expressed as the number of days in which corrosion progressed by 5%. As a result, Ti, Zr, Hf, V, Nb, Ta, Mo, W,
A ferromagnetic film containing B, N, C, and O, as well as Cr, Mo, and W has a coercive force of 0.9 even after heat treatment at a high temperature of 550°C.
It was revealed that it has excellent soft magnetic properties of Oe or less. Furthermore, the results of the corrosion test at this time confirmed that all samples exhibited corrosion resistance for 50 days or more.

Similarly, Ti, Zr, Hf, V, Nb, Ta, and Mo are added to the ferromagnetic metal film containing Fe and Co as main components.
, W and B, C, N, O elements but without Cr were also considered, but the coercive force value increased by 5 to 20% and the corrosion resistance was 2/2 compared to the case with Cr addition. It was confirmed that it deteriorated in 3 days or less (Table 1 shows a comparative example in which only Ta and C were added). In addition, noble metal materials such as Rh, Ru, and Pt, which are conventionally known as elements that improve corrosion resistance,
The above-mentioned ferromagnetic film in which Cr was added instead of Cr was also prepared, and after being heat-treated in the same manner, its soft magnetic properties and corrosion resistance were examined. As a result, the corrosion resistance was improved in the same manner as when Cr was added, but the coercive force was increased compared to the above-mentioned ferromagnetic film without Cr addition, and the characteristics were deteriorated. When the magnetostriction constants of the obtained ferromagnetic films were measured, it was found that the ferromagnetic films without Cr addition and the ferromagnetic films with Cr addition had -5
It was confirmed that the magnetostriction constant exhibited a value between ×10 −7 and 5×10 −7 and exhibited a preferable magnetostriction constant.

On the other hand, the magnetostriction constant of the ferromagnetic film doped with Rh, Ru, and Pt instead of Cr is from 1×10 −6 to 9
It was confirmed that it showed a large value of x10-6. Therefore, the inventors of the present invention conjectured that by adding Rh, Ru, and Pt, the magnetostriction constant of the ferromagnetic film increases and the soft magnetic properties deteriorate.

[0022] The above results revealed that the addition of Cr improves the corrosion resistance without substantially changing the soft magnetic properties and magnetostriction constant.

As a result of XPS analysis of the ferromagnetic film immediately after film formation and the ferromagnetic film heat-treated at 550°C, it was found that Ti, Zr, Hf, V, Nb, Ta, Mo, and W were present in the film immediately after film formation.
was generally in a metallic state, and B, C, N, and O elements were also free. However, after heat treatment at 550°C, Ti, Zr, Hf, V, Nb, Ta, Mo, W and B,
Bonds of C, N, and O elements were observed, and it was confirmed that they had changed to borides, carbides, nitrides, and oxides with high melting points. From these results, it is predicted that the reason why the ferromagnetic metal film exhibits excellent soft magnetic properties even after heat treatment at high temperatures is that these high melting point materials exist around the ferromagnetic metal crystal grains and suppress the growth of the crystal grains. be done. In fact, as shown in Table 1, even after heat treatment at 550°C, the crystal grain size of the ferromagnetic film of the present invention was 15nm.
m or less, and it is thought that these microcrystals maintain soft magnetic properties up to high temperatures. It was also confirmed that the addition of Cr made the crystal grains finer.

As a result of examining the magnetic film of the present invention using an X-ray diffraction method, the crystal structure of the main components excluding borides, carbides, nitrides, and oxides was found to be Fe-based, up to the film heat-treated at 700°C. In this case, the structure was body-centered cubic, and in the case where Co was the main component, it was a hexagonal close-packed structure. Both are boride,
The main components other than carbides, nitrides, and oxides had no other structures and were single-phase.

[Example 2] A soft magnetic film was formed in the same manner as in Example 1 by changing the concentration of Cr added to the Fe80Ta9C11 ferromagnetic metal film, and
Its magnetic properties and corrosion resistance were evaluated. Measured at 550℃
The measurements were taken after heat treatment for 1 hour. Figure 1 shows the influence of Cr concentration on corrosion days and magnetostriction constant. Note that the number of days of corrosion resistance was determined by a constant temperature and humidity test at 80° C. and 90% humidity as in Example 1. As is clear from the figure, as the Cr concentration increases, the number of days of corrosion resistance increases, and it is clear that the addition of Cr is effective in improving corrosion resistance. On the other hand, the magnetostriction constant gradually increases from negative to positive values,
Adding a large amount of Cr makes it difficult to control the magnetostriction constant.

As a result, Cr-added Fe80Ta9
It was confirmed that the C11 film exhibits excellent soft magnetic properties with a coercive force of 0.9 Oe or less. At this time, the crystal grains are bcc
It was confirmed that the crystal had a structure and was kept in the form of microcrystals of 15 nm or less. Corrosion resistance is observed to improve when the Cr concentration is 0.1 at% or more, but the magnetostriction constant shows a value of 1×10 −6 or less when the Cr concentration is 10 at% or less. However, it has also been found that the magnetostriction constant of the ferromagnetic film changes depending on the heat treatment temperature, and that the preferable Cr concentration tends to increase as the heat treatment temperature of the ferromagnetic film increases. Therefore, a Cr concentration of 0.1 to 10 at% is generally a preferable value.

[Example 3] In Example 1, the element added to the ferromagnetic metal film Fe80Ta9C11 was changed from only Cr to simultaneous addition of Cr and Mo and simultaneous addition of Cr and W.
The same study as in Example 1 was conducted. Coercive force and corrosion resistance are 55
This value was measured after heat treatment at 0° C. for 1 hour. Note that the corrosion resistance was measured in the same manner as in Example 1. The coercive force of the obtained ferromagnetic metal film was almost the same as when only Cr was added, and showed a value of 0.9 Oe or less.

The amount of Cr added to the ferromagnetic metal film is 3at.
%, and the results of examining the magnetostriction constant and corrosion resistance of ferromagnetic films formed by varying the amounts of Mo and W added simultaneously are shown in FIG. As shown in the figure, the corrosion resistance is C
This was a further improvement compared to when only r was added. Approximately 0
．． Further improvement in corrosion resistance was observed by adding 1 at % or more of Mo or W. At this time, the magnetostriction constant of the ferromagnetic film increases with the addition of Mo or W, and if it is added in an amount of 10 at % or more, the magnetostriction constant becomes 1×10 −6 or more, which is not preferable. Accordingly, an increase in coercive force was also observed.

From the above results, it has become clear that the concentration of Mo or W to be added simultaneously with Cr is preferably 0.1 at% to 10 at%.

The saturation magnetic flux density of the obtained ferromagnetic metal film was 1.4 T to 2.0 T, and the value of the saturation magnetic flux density tended to decrease as the total amount of added elements increased.

[Example 4] Using the ferromagnetic films obtained in Examples 1 to 3, a magnetic pole for a metal-in-gap head was fabricated as shown in FIG. 3, and evaluated as a head for a high-density magnetic recording device. did. FIG. 3A shows an overall perspective view, and FIG. 3B shows an enlarged view of the vicinity of the gap. Mn-Zn ferrite substrate 1
Then, the magnetic cores to which the ferromagnetic film 2 with a thickness of 5 μm is attached are butted against each other to form a gap 4. Gap length is 0.
It is 2 μm. A coil 5 is provided in the magnetic core. Glass bonding temperature during head formation is 520℃
It is. The medium used had a coercive force of 1500 Oe. As a result, the recording characteristics of the head using the Fe-based ferromagnetic film of the present invention for the magnetic pole of the head were improved by 4.3 dB compared to the conventional Sendust head, and the reproduction output was approximately 3.5 dB higher. Furthermore, a recording density of 100 kBPI or more could be obtained. This is because the ferromagnetic film of the present invention has a higher saturation magnetic flux density than other materials.

Furthermore, as a result of measuring the pseudo signal output due to the pseudo gap effect of the head, it was found that Nb
, Zr, Ti, Ta, Hf, Cr, W, Mo, and nitrogen or carbon added at the same time for the magnetic pole of the head, a spurious signal output of 3 to 5 dB was detected, but the present invention When using this magnetic film, it was confirmed that the pseudo signal output was reduced to 2 dB or less. When the glass adhesive part of the obtained head was peeled off and depth analysis was performed using Auger electron spectroscopy from the magnetic film side toward the ferrite, it was found that in the conventional head, there was 50 to 180 Å of oxidation at the interface between the magnetic film and ferrite. The existence of a layer was confirmed. On the other hand, in the head of the present invention, the oxide layer at the interface between the magnetic film and the ferrite is at most 20 Å, and the magnetic film contains C.
It was revealed that the presence of r suppressed the interfacial reaction, making the oxide layer thinner and reducing the spurious signal output.

In addition, when a conventional magnetic film is used for the magnetic pole, a reaction occurs between the magnetic film and the filler glass during glass bonding, and a part of the magnetic film changes to a film with poor soft magnetic properties, causing the recording/reproduction of the head to become difficult. properties deteriorated. Furthermore, in severe cases, a film with high coercive force may be formed, which may erase signals previously recorded on the medium. However, in the present invention, no formation of a reaction layer was observed even when the interface between the magnetic film and the filled glass was observed using an optical microscope, and high recording and reproducing characteristics were exhibited.

In the above embodiments, the magnetic film was formed by RF sputtering, but the present inventors have also conducted similar studies using ion beam sputtering, and found that magnetic films with almost similar magnetic properties and heat resistance were formed using ion beam sputtering. It was confirmed that a film was formed. Therefore, the present invention is effective regardless of the film formation method.

[0035]

As described above in detail, the corrosion-resistant soft magnetic film according to the present invention has good soft magnetic properties up to a temperature of at least 600° C., and its saturation magnetic flux density is maintained high. In addition, this soft magnetic film not only has extremely excellent corrosion resistance, but also prevents the formation of reaction layers such as oxides at the interface between the magnetic film and ferrite. In particular, when used in a metal-in-gap magnetic head, glass bonding can now be performed at a high temperature of 500° C. or higher, and a glass layer with sufficient strength can be formed. Further, the pseudo signal output based on the pseudo gap was also a low value of 2 dB or less.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the influence of the Cr concentration in the film on the magnetostriction constant and corrosion resistance days of the ferromagnetic film of the present invention.

FIG. 2 is a graph showing the influence of Mo and W concentrations in the film on the magnetostriction constant and corrosion resistance days of the ferromagnetic film of the present invention.

FIG. 3(A) is a perspective view of the magnetic head of the present invention, (
B) is a plan view showing the vicinity of the gap portion of the magnetic head of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Substrate, 2...Ferromagnetic film, 3...Filled glass, 4...Gap, 5...Coil.

Claims (13)

[Claims] [Claim 1] Ti, Zr, Hf, V, Nb, Ta, Mo
, at least one element selected from W and B, C,
A corrosion-resistant soft magnetic film characterized in that Cr is present in a ferromagnetic metal film containing at least one element selected from N and O. 2. The corrosion-resistant soft magnetic film according to claim 1, wherein the ferromagnetic metal film is made of microcrystals containing Fe or Co as a main component. 3. The Ti, Zr, Hf, V, Nb, Ta,
2. The corrosion-resistant soft magnetic film according to claim 1, wherein the concentration of at least one element selected from Mo and W in the ferromagnetic metal film is from 0.5 to 15 at%. 4. Corrosion resistance according to claim 1, characterized in that the concentration of at least one element selected from B, C, N, and O in the ferromagnetic metal film is from 0.5 to 15 at%. Soft magnetic film. 5. The corrosion-resistant soft magnetic film according to claim 1, wherein the concentration of Cr in the ferromagnetic film is from 0.1 to 10 at%. [Claim 6] Ti, Zr, Hf, V, Nb, Ta, Mo
, at least one element selected from W, B, C,
A corrosion-resistant soft magnetic film characterized in that Mo or W is simultaneously present in a ferromagnetic metal film containing at least one element selected from N and O and Cr. 7. The corrosion-resistant soft magnetic film according to claim 6, wherein the ferromagnetic metal film is made of microcrystals containing Fe or Co as a main component. 8. The Ti, Zr, Hf, V, Nb, Ta,
3. The corrosion-resistant soft magnetic film according to claim 2, wherein the concentration of at least one element selected from Mo and W in the ferromagnetic metal film is from 0.5 to 15 at%. 9. Corrosion resistance according to claim 2, characterized in that the concentration of at least one element selected from B, C, N, and O in the ferromagnetic metal film is from 0.5 to 15 at%. Soft magnetic film. 10. The concentration of Cr in the ferromagnetic film is 0.1.
3. The corrosion-resistant soft magnetic film according to claim 2, wherein the corrosion-resistant soft magnetic film has a content of from 10 at% to 10 at%. 11. The corrosion-resistant soft magnetic film according to claim 2, wherein the concentration of Mo or W in the ferromagnetic film is from 0.1 to 10 at%. 12. A magnetic head comprising a magnetic circuit having the corrosion-resistant soft magnetic film according to claim 1 or 6, a coil magnetically coupled to the magnetic circuit, and a magnetic gap provided in a part of the magnetic circuit. . 13. The magnetic head according to claim 12, wherein the magnetic circuit is formed by bonding a pair of magnetic cores each having the magnetic film adhered to a substrate using glass.