JP2635674B2 - Magnetic thin film for thin film magnetic head and method of manufacturing the same - Google Patents

Description

The present invention relates to a structure of a magnetic thin film for a thin-film magnetic head used as a material for a magnetic pole of a thin-film magnetic head and a method of manufacturing the same.
In particular, it is intended for a thin film magnetic head corresponding to a high density recording medium.

[Conventional technology and its problems]

Conventionally, an 80 permalloy film made of 80% by weight of nickel and the balance of iron has been used as a magnetic thin film for a thin film magnetic head. This is described, for example, in Japanese Patent Application Laid-Open No. 60-10410.
No. 6,086,045. Since the 80 permalloy film has a high magnetic permeability in a high frequency region, a thin film magnetic head using this as a magnetic pole material has excellent read performance.

However, this 80 permalloy has a saturation magnetic flux density of about
Since it is as low as 10 kilogauss, the thin-film magnetic head using this as a magnetic pole material has poor writing performance. Higher coercivity of the medium is indispensable for high density recording in the future, and when a high coercivity high density medium such as a metal medium is used,
With a thin film magnetic head using 80 permalloy as the pole material, the write performance is insufficient. Therefore, a pole material having a higher saturation magnetic flux density is required.

At present, as materials having higher saturation magnetic flux density than 80 permalloy, sendust (Fe-Si-Al) and amorphous cobalt (Co-Nb-Zr, etc.) are being developed. Each of these sendust and amorphous cobalt formation methods employs a dry film formation method in plasma using a sputtering method.

Further, for example, JP-A-63-80509 discloses Co, F
It discloses a laminated film of a metal containing at least one of e and Ni as a main component, and also includes a Co-Fe-Ni ternary alloy. However, Japanese Patent Application Laid-Open No. 63-80509 does not disclose the above-mentioned Co-Fe-Ni ternary alloy, particularly the composition of permbar. Further, in the example of this publication, the ion beam sputtering method, that is, a dry film forming means is used, and the thickness of the intermediate layer is from 0.05 to
For forming a superlattice film as thin as 5 nm, ion beam sputtering seems to be suitable for low-speed film formation in order to improve the controllability of the film thickness.

As described above, means for forming a conventional magnetic film having high saturation magnetic flux density and soft magnetism and capable of high density recording is limited to only a material that can be formed by a dry film forming means.

However, this dry film forming means has problems such as plasma damage, a rise in substrate temperature during film formation, high cost, and low mass productivity. For this reason, it is very difficult to apply it to the manufacturing process of a thin film magnetic head,
Development of a material having high saturation magnetic flux density and soft magnetism by wet plating is required.

In recent years, in a magnetoresistive head, which has attracted attention as a thin film head compatible with a high recording density, a conventional thin film head, that is, an inductive head is used exclusively for writing. For this reason, in order to sufficiently write data on a medium having a high coercive force, there is a tendency that higher saturation magnetization, which is more important for writing performance, is more important than magnetic permeability, which is more important for reproduction efficiency.

[Object of the invention]

Therefore, an object of the present invention is to provide a soft magnetic property having a magnetic permeability (μ) of 1000 or more, a saturation magnetic flux density (Bs) of 14 kGauss or more, and a coercive force (Hc) of 0.5 Oe or less, which are desirable as a magnetic pole material of a thin film magnetic head for high density recording. An object of the present invention is to provide a magnetic film structure having the same and a manufacturing method thereof.

[Means for solving the problem]

In order to achieve the above object, a magnetic thin film for a thin film magnetic head according to the present invention and a method for manufacturing the same employ the following means.

(A) In the magnetic thin film for a thin film magnetic head of the present invention, a Perminbar type ternary alloy film composed of 32 to 54% by weight of nickel, 16 to 48% by weight of cobalt, and 10 to 34% by weight of iron; % And a total of five or more layers alternately laminated with an 80 permalloy film made of residual iron, and the film thickness of the Permimber type ternary alloy film is in the range of 2 to 5 times the 80 permalloy film.

(B) In the method for producing a magnetic thin film for a thin film magnetic head of the present invention, nickel
The Perminbar type ternary alloy film consisting of 16-48% by weight and 10-34% by weight of iron and the 80% Permalloy film consisting of 75-85% by weight of nickel and the balance of iron are alternately laminated to form a total of five or more layers. The method of manufacturing a magnetic thin film for a thin-film magnetic head in which the thickness of the mold ternary alloy film is in the range of 2 to 5 times the thickness of the 80 permalloy film is disclosed in US Pat.
The original alloy film and the 80 permalloy film are formed by a wet plating method.

[Action]

Improving the recording density of a magnetic head is always a technical issue. For both rigid disks and floppy disks, it is desired to improve the recording density. For this purpose, efforts are being made from both track density and linear recording density. The present invention relates to improvement in linear recording density.

The linear recording medium is determined by the recording medium and the head characteristics. According to “Theory of Magnetic Recording” (by Masaaki Nishikawa, Asakura Shoten), the following relationship exists between the characteristics of the recording medium and the magnetization reversal density D50. (Pages 159 and 163 of the aforementioned book) D50 ≒ 1.38 / W50 = 1.38 (Hc / Br) ^0.5 δ- ^(0.7 to ^0.8) where W50: Half width of isolated reproduction waveform Hc: Retention force of recording medium Br: Remanent magnetization of recording medium δ: thickness of recording medium.

That is, the magnetization reversal density (linear recording density) D50 is determined by the coercive force, the residual magnetization, and the thickness of the recording medium. Decreasing the remanent magnetization and thickness can increase the magnetization reversal density (linear recording density) D50, but these two parameters are naturally limited in terms of reproduction output.
Therefore, D50 is mainly determined by the recording medium holding force. That is, as the medium holding force Hc increases, the linear recording density increases.
D50 increases. By the way, when the medium holding force Hc is increased, it is necessary to increase the write magnetic field of the head accordingly, and the write magnetic field of the head is determined by the saturation magnetic flux density Bs of the head magnetic pole material.

The write magnetic field Hxmax is represented by Hxmax = (2Hg / π) tan ⁻¹ (g / 2y).

Here, Hg: magnetic field in the gap g: gap length y = {d (d + δ)} ^1/2 d: separation length between head and medium δ: medium thickness

The magnetic field Hg in the gap has the following relationship: Hg ≦ Bs where Bs: saturation magnetic flux density of the magnetic material. When other parameters are fixed, the write magnetic field Hxmax is determined by the saturation magnetic flux density Bs of the magnetic pole material.

Nakanishi et al.'S report (Tsukuken R & D Report No. 28, No. 10,
According to 1979, p. 149), the magnetic field required for erasing (overwriting) is three times the medium coercive force Hc.

Based on the above considerations, the relationship between the coercive force Hc of the magnetic recording medium currently used or that will be used in the future and the linear recording density D50, and the saturation magnetic flux density Bs of the writable magnetic pole material is described. It is shown in FIG.

According to the results shown in FIG. 3, the magnetic pole material 80 Permalloy conventionally used for the thin film magnetic head has Bs = 10 kilogauss (KG) and Co-γFe2O3 (Hc = 720 Oersted (O
e), up to D50 = 28KBPI)
Insufficient writing on metal coated media (Hc1500Oe, D50 = 46KBPI). Therefore, a pole material having a higher saturation magnetic flux density Bs is desired.

Perminbar having a structure mainly composed of 45% by weight of Ni, 30% by weight of Fe, and 25% by weight of Co has a high saturation magnetic flux density of about 14 to 18KG and has excellent writing characteristics. However, the permeability μ is about
As low as 400-600. According to CWSteel et al.
It is said that about 100 is a standard for suppressing the deterioration of the Hx distribution.

According to "Theory of Magnetic Recording" (by Nishikawa),
The reproducing head is required to have a core having a magnetic permeability one digit larger than that of the recording head. (Page 113) That is, when the magnetic permeability μ is 100 or less, the area is not readable and writable. When the magnetic permeability μ is 100 to 1000, the area is readable only.

FIG. 4 evaluates the performance of the 80 permalloy and perminbar compositions based on this consideration. 80 permalloy is μ = 2000
However, when Bs = 10KG, the writing performance on the metal-coated medium is insufficient. On the other hand, Bs = 15 ~
Although it is as high as 18KG, it is as low as μ = 400-600 and has poor reading performance.

The present invention relates to 80 permalloy and permbar type Co-Fe-Ni
Alternately stacking ternary films, Bs> 14KG, μ> 1000, Hc <0.5Oe
As shown in FIG. 2, there is provided a magnetic thin film for a thin film magnetic head having a performance satisfying both reading and writing with respect to a metal coated medium. Hereinafter, an embodiment will be described.

〔Example〕

(Example 1) A method of forming an 80 permalloy film using a wet plating method is as follows.
The plating solution was adjusted using a watt bath, which is often used in Ni plating, as a main component. NiSO4 as Ni component in plating bath
・ 7H2O, NiC12.6H2O, other than FeSO4.7H2O as Fe component
An appropriate amount of H3BO3 as a pH buffer, sodium saccharin as a brightener, and sodium lauryl sulfate as a surfactant were added. After filtration, the plating bath was adjusted with H2SO4 to a pH of 2.2.

In the plating of the permbar film, CoSO4.7H2O was added as a Co component to the plating bath described above.
The plating solution was set at a bath temperature of 40 ° C., the solution was circulated by a magnetic pump, and a filter was introduced into the circulation system. After passing through the filter, the plating solution was jetted between the cathode (substrate) and the anode (counter electrode) to supply the plating solution and agitate the bath. As a result, variations in the composition distribution and film thickness distribution of the plating film can be suppressed. The anode is usually Ni
Although a plate is used, a Ti-Pt net which does not affect the bath composition is used in this example. The power supply was controlled by galvanostat under constant current control. In order to enhance the adhesion of the plating film, so-called strike plating in which a plating current of about three times the current density during normal plating is applied for a very short period of time for about 5 seconds may be performed. Has almost no effect. The substrate was formed on a glass substrate for measurement of magnetic properties by sputtering as a plating base film with a thickness of 100 nm permalloy film.

(Example 2) 80 permalloy was NiSO4.7H2O (300 g / l), NiCl12.6H2
O (30g / l), FeSO4 ・ 7H2O (30g / l), others are H3BO3
(40 g / l), a saccharin sodium (1.5 g / l), and a plating solution containing sodium lauryl sulfate (0.25 g / l) were obtained by setting the plating current density to 7 mA / cm2.

In addition, for the film with the perminbar composition, CoSO4.7H2O
(10-200g / l), NiSO4.6H2O (200g / l), NiCl2.6H2O
(30g / l), FeSO4.7H2O (10-150g / l), other H3BO3
(40 g / l), a saccharin sodium (1.5 g / l), and a plating bath containing sodium lauryl sulfate (0.25 g / l). The composition of the deposited film was controlled by changing the ratio of the amounts of the Co, Fe, and Ni components in the bath and the plating current density.

(Example 3) 80 permalloy described in the first example and Bs = 17K
Lamination with a Co37Fe28Ni35 film of G, μ = 400 was performed. The film of this Perminbar composition is composed of CoSO4.7H2O (50 g / l), NiSO4
・ 6H2O (200g / l), NiCl2.6H2O (30g / l), FeSO4.7H2
O (120 g / l), a plating solution comprising H3BO3, sodium saccharin, and sodium lauryl sulfate were obtained by setting the plating current density to 7.2 mA / cm2.

Next, a laminated film of the Co37Fe28Ni35 film and the 80 permalloy film was prepared. The lamination can be obtained by alternately immersing in the two types of plating baths described above. However, since the composition of the respective plating solutions fluctuates, unnecessary plating solutions adhering to the jig are preferably cleaned with a pure water cleaning tank. It is preferable to provide a space between the two plating baths so as to sufficiently drop them.

In this way, the saturation magnetic flux with respect to the thickness of one layer of a total of five layers in which the Co37Fe28Ni35 film is alternately laminated as the first layer, the third layer, and the fifth layer, and the 80 permalloy film is the second layer and the fourth layer. density
FIG. 1 shows the relationship between Bs and the magnetic permeability μ (measured at 4 MHz). The thickness of one layer of 80 permalloy is 100 nm.

As is clear from FIG. 1, when the film thickness ratio of perminbar to 80 permalloy is in the range of 2 to 5, Bs> 14KG and μ> 10
00, which proves that a soft magnetic thin film having sufficient performance for reading and writing on the metal-coated medium can be obtained.

(Example 4) 80 permalloy described in the first example, Bs = 15.6KG,
Lamination with a Co31Fe21Ni48 film of μ = 600 was performed. The film of this Perminver composition is composed of CoSO4.7H2O (40 g / l), NiSO4.6
H2O (200g / l), NiCl2.6H2O (30g / l), FeSO4.7H2O
(140 g / l), and a plating solution comprising H3BO3, sodium saccharin, and sodium lauryl sulfate at a plating current density of 7.5 mA / cm2.

This Co31Fe21Ni48 film is formed into a first layer, a third layer, and a fifth layer,
Saturation magnetic flux density Bs and magnetic permeability μ relative to the thickness of one layer of a total of five layers of 80 permalloy alternately laminated as a second layer and a fourth layer
(4 MHz measurement) is shown in FIG. The thickness of one layer of 80 permalloy was 100 nm.

As is clear from FIG. 2, when the thickness ratio of perminbar to 80 permalloy is in the range of 2 to 5, Bs> 14KG, μ>
It was 1000, which proved that a soft magnetic thin film having sufficient performance for reading and writing a metal-coated medium was obtained.

(Example 5) A thin-film magnetic head for a floppy disk having both upper and lower magnetic pole thicknesses of 2.3 µm, a track width of 40 µm, a gap length of 0.3 µm, a gap depth of 2 µm, and a coil turn of 50 turns (double coil) was manufactured. Head A has Co37Fe28Ni35 film
The magnetic pole material was a laminated magnetic thin film consisting of four layers at 500 nm, three layers of 80 permalloy having a thickness of 100 nm, a total of seven layers, and a total thickness of 2.3 μm. The head B was made of an 80 permalloy single-layer film as a magnetic pole material. The head C was made of a Co37Fe28Ni35 single layer film as a magnetic pole material.

Table 1 below shows the read / write performance of the head A, the head B, and the head C on the metal coating medium (Hc = 1500 Oe), that is, the output voltage and the overwrite characteristics. The head B lacks overwriting, and the head C lacks output voltage. That is, with the Perminbar type alloy film according to the present invention,
Only the head A using a magnetic thin film obtained by alternately laminating 80 permalloy with magnetic pole material showed sufficient read / write performance.

[Effects of the Invention] As is clear from the above description, according to the present invention, a magnetic thin film for a thin film magnetic head having high coercive force and excellent read / write performance for a high-density magnetic recording medium is excellent in mass productivity and process matching. Can be obtained by a wet plating method.

[Brief description of the drawings]

1 and 2 are tables showing the relationship between the formation factor of the laminated magnetic thin film and the saturation magnetic flux density Bs and the magnetic permeability μ in the embodiment of the present invention, and FIG. 3 is a table showing the linear recording densities of various magnetic recording media. The saturation magnetic flux density Bs of the head magnetic pole material with write performance
FIG. 4 is a chart showing the relationship between the saturation magnetic flux density Bs of the head magnetic pole material, the magnetic permeability μ, and the read / write performance of the head.

Claims (2)

(57) [Claims] 1. The method of claim 1 wherein the nickel is 32 to 54 weight percent cobalt.
The Perminbar type ternary alloy film consisting of 16-48% by weight and 10-34% by weight of iron and the 80% Permalloy film consisting of 75-85% by weight of nickel and the balance of iron are alternately laminated to form a total of five or more layers. A magnetic thin film for a thin-film magnetic head, wherein the thickness of the mold ternary alloy film is in the range of 2 to 5 times the 80 permalloy film. 2. The method of claim 1 wherein the nickel is 32 to 54 weight percent cobalt.
The Perminbar type ternary alloy film consisting of 16-48% by weight and 10-34% by weight of iron and the 80% Permalloy film consisting of 75-85% by weight of nickel and the balance of iron are alternately laminated to form a total of five or more layers. The method of manufacturing a magnetic thin film for a thin-film magnetic head in which the thickness of the mold ternary alloy film is in the range of 2 to 5 times the thickness of the 80 permalloy film is disclosed in US Pat.
A method for producing a magnetic thin film for a thin film magnetic head, wherein the original alloy film and the 80 permalloy film are formed by a wet plating method.