JP2000208355A - Manufacture of soft magnetic alloy plated thin film and the film and thin-film magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a soft magnetic alloy plated thin film with high saturated magnetic flux density, superior soft magnetic characteristics, high specific resistance, and superior write and read characteristics. SOLUTION: Each dihydric ion of Co, Ni, and Fe is supplied to plating liquid by salt containing each dihydric ions of Co, Ni, and Fe, and at least one kind from among molybdic acid ion, tungstic acid ion, and vanadic acid ion, and chrome (III) ion is doped to the plating liquid. In this case, by having electric plating conducted in the plating liquid in which the ion concentration of the dopant ion is 1×10-5 mol/l or higher and 2×10-4 mol/l or lower so that a soft magnetic alloy plated thin film can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating thin film mainly used as a magnetic pole of a thin film magnetic head suitable for high-density magnetic recording, which has a high saturation magnetic flux density, a high specific resistance, and a low coercive force. The present invention relates to a soft magnetic alloy plating thin film having a low magnetostriction constant and a method of manufacturing the same, and a thin film magnetic head using such a soft magnetic alloy plating thin film as a magnetic pole layer of an inductive head.

[0002]

2. Description of the Related Art In recent years, plating thin films are widely used not only for decoration and anticorrosion but also for electronic parts and the like as functional thin films. For example, in a thin film magnetic head of a hard disk drive as an external storage device for a computer, a permalloy alloy thin film manufactured by a plating method is used as a magnetic material constituting a magnetic pole layer of an inductive head.

[0003] Permalloy is a typical soft magnetic alloy material used for a plating thin film, particularly Ni ₈₂ at% Fe ₁₈ at%.
Is characterized by having a zero or negative magnetostriction constant.

As hard disk drives are increasingly demanded for higher capacity and smaller size year by year, recording density is increasing, and a material having a high saturation magnetic flux density is required as a magnetic material of a head. ing.

However, if the Fe content is increased in order to obtain a higher saturation magnetic flux density in a permalloy film, the domain structure becomes unstable because the magnetostriction constant increases. Therefore, the permalloy film has a limitation in achieving a high saturation magnetic flux density when used in a pole layer of a thin-film magnetic head.

FIG. 1 is a diagram showing the distribution of saturation magnetic flux density in a Co—Ni—Fe ternary alloy. The region indicated by A in the drawing has a high saturation magnetic flux density and a small magnetostriction constant, and is therefore expected to be promising as a magnetic material for a thin-film magnetic head. U.S. Pat. No. 4,661,21
No. 6 also describes a Co—Ni—Fe ternary alloy plated thin film having a magnetostriction constant of 0 and a high saturation magnetic flux density.

However, the above-mentioned conventional Co-Ni-
Since the effective specific resistance is as low as about 10 μΩ · cm in the composition region of the Fe ternary alloy plating thin film, the writing characteristics in the high frequency region become unstable.

Attempts have been made to increase the specific resistance of the plated thin film for the purpose of improving the writing characteristics in the high frequency range. Proceedings of the Japan Society of Applied Magnetics Science Conference p2
07 (1998), the conventional material Ni ₈₀ Fe
Studies have been made on increasing the specific resistance by adding Mo to ₂₀ . According to the above literature, Mo is about 3 at%.
With the added Mo ₃ Ni ₈₀ Fe ₁₇ film, a soft magnetic plating thin film having zero magnetostriction and a high specific resistance of about 47 μΩcm can be obtained. However, there is a problem that the saturation magnetic flux density is as low as about 1.0T.

For the purpose of obtaining a high saturation magnetic flux density, a high specific resistance plating thin film using Ni ₄₅ Fe ₅₅ having a higher saturation magnetic flux density than Ni ₈₀ Fe ₂₀ has also been studied. Japanese Patent Application Laid-Open No. 9-63016 discloses that Ni ₄₅ Fe
By introducing an additive element of 1 to 3 at% to ₅₅ , the saturation magnetic flux density is 1.5 to 1.6 T and the specific resistance is 50 to 60 μΩcm.
Has been realized. However, there is a problem that these soft magnetic plating thin films have a large magnetostriction of about + 5 × 10 ⁻⁶ .

In view of the above, at present, a soft magnetic alloy thin film having high specific resistance, high saturation magnetic flux density, and O magnetostriction utilizing a plating method excellent in productivity and a method for producing the same have not yet been developed.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a magnetic alloy thin film manufactured by a plating method mainly used as a magnetic material of a thin film magnetic head suitable for high-density magnetic recording. It is an object of the present invention to provide a plating thin film which is affected by magnetic properties and has a high specific resistance and has excellent writing and reading performances, and a method for manufacturing the same.

[0012]

As described above, Co-N
The i-Fe ternary alloy plated thin film has a high saturation magnetic flux density but a low specific resistance. Therefore, the saturation magnetic flux density is high,
In order to obtain a plating thin film having high specific resistance and high specific resistance, the present inventor added Mo, C in the plating film by adding an additive to a plating bath at the time of Co—Ni—Fe ternary alloy plating.
The present invention was completed as a result of examining the inclusion of r, W, and V and conducting various experiments.

That is, according to the method for producing a soft magnetic alloy plating thin film of the present invention, Co, Ni and Fe divalent ions are supplied to the plating solution by a salt containing Co, Ni and Fe divalent ions. At the same time, at least one of molybdate ion, tungstate ion, vanadate ion and chromium (III) ion is added to the plating solution, and the ion concentration of the added ion is 1 × 10 ⁻⁵ mol.
A soft magnetic alloy plating thin film is formed by performing electroplating in a plating solution of not less than / l and not more than 2 × 10 ^-4 mol / l. By this manufacturing method, a soft magnetic alloy plating thin film containing Co, Ni, Fe as a main component and containing at least one of Mo, W, V, and Cr as an additive element in an amount of 1 at% to 5 at% is formed. Film.

High-frequency response is an indispensable characteristic of a magnetic material of a thin-film magnetic head capable of coping with high-density recording. As the frequency of the magnetization response of the thin-film magnetic head increases, that is, as the magnetization change per unit time of the thin-film magnetic head magnetic body increases, the eddy current flowing inside the magnetic body increases. The eddy current generates a magnetic flux that obstructs a change in magnetic flux according to Lenz's law. As a result, the magnetization change is suppressed as the signal becomes higher in frequency. Here, the eddy current flowing inside the magnetic body is inversely proportional to the specific resistance of the magnetic body. Therefore, high specific resistance is required to obtain good high-frequency characteristics.

Therefore, when the specific resistance of the magnetic material is increased by mixing impurities in the plating film, a decrease in magnetization change due to eddy current is suppressed, and high-frequency response is improved. In the present invention, the reason why Mo, Cr, W, and V are contained in the Co—Ni—Fe ternary alloy plating film is to utilize an increase in specific resistance.

Also, with the recent increase in recording density of hard disk drives, a magnetic medium using a magnetic material having a high coercive force has been used, so that the magnetic material constituting the pole layer of the thin-film magnetic head has a high saturation flux. It is required to have a density. Experiments conducted by the present inventors have revealed that, when the composition ratio of the above-mentioned additional elements is too large, the saturation magnetic flux density becomes small, and characteristics as a magnetic material of a magnetic head for a high-density hard disk cannot be obtained. In the present invention, the concentration of the added ions is limited to a certain range for this reason.

In a thin-film magnetic head having an inductive head for performing magnetic recording on a magnetic recording medium by generating a magnetic field between the tip portions of upper and lower magnetic pole layers stacked vertically via a recording gap layer, When one or both are formed by the above-described method for producing a soft magnetic alloy plating thin film, the pole layer has high specific resistance and thus has excellent high-frequency characteristics, and also has a high saturation magnetic flux density and low magnetostriction. It has good reproduction / recording characteristics and can withstand even higher speed / high density magnetic recording.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described. The plating solution used in the production method of the present invention can supply each divalent ion of Fe, Co and Ni by sulfate and / or hydrochloride. The plating solution contains one or more, preferably two or more of molybdate, tungstate, vanadate and chromium (III) ions. C in plating solution
The contents of o, Ni, and Fe are adjusted according to the plating conditions.

In order to obtain a film having a smaller magnetostriction constant,
The lower the composition ratio of Fe in the film, the better the concentration of Fe ions in the plating solution is. C in plating solution
Each ion concentration of o, Fe, Ni is 0.05 mol of Co ²⁺
/ 1 or more and 0.1 mol / l or less, Ni ²⁺ 0.2 mol /
l or more. 3 mol / l or less, Fe ²⁺ 0.01 mol /
It is desirable that the content be 1 to 0.3 mol / 1.

In order to obtain a higher specific resistance, it is desirable that the composition ratio (atomic%) of Mo, Cr, W and V in the plating film is higher. To obtain a higher saturation magnetic flux density, M
It is desirable that the composition ratio (atomic%) of o, Cr, W, and V be low. Due to such factors, Mo, Cr, W,
A desirable composition ratio of V is 1 to 5 atomic%.

The concentration of molybdate, tungstate, vanadate and chromium (III) ions in the plating solution is adjusted according to the plating conditions. It is desirable that the concentrations of acid ions, tungstate ions, vanadate ions, and chromium (III) ions be high. In order to obtain a higher saturation magnetic flux density, it is desirable that the concentrations of molybdate ion, tungstate ion, vanadate ion, and chromium (III) ion in the plating solution be low.
Therefore, in order to obtain a soft magnetic alloy plating thin film having high saturation magnetic flux density and high specific resistance, the total added ion concentration of molybdate ion, tungstate ion, vanadate ion and chromium (III) ion in the plating solution is 1 × 1O ^-5 m
The range is preferably from ol / l to 2 × 10 ⁻⁴ mol / l.

In order to obtain a plating film stably, a stress relieving agent, a surfactant and a pH buffer are usually added, and the concentration is appropriately adjusted. In order to stably obtain a smooth plating film, the pH of the plating solution is desirably 2 or more and 4 or less. If it exceeds 4, oxidation of Fe ²⁺ occurs. If it is less than 2, hydrogen is generated on the surface of the object to be plated, which makes it difficult to control the thickness of the plated film and results in a plated film having a rough surface.

In order to obtain a higher saturation magnetic flux density, it is desirable that the Co content in the magnetic material of the plating film is 50% or more and the Fe content is 5% or more. In order to obtain excellent soft magnetic properties, it is desirable that the Co content is 90% or less and the Fe content is 20% or less. In addition, the magnetostriction constant is set to 0
In order to obtain a near value, the Fe content in the film is desirably 10% or less.

In order to obtain excellent soft magnetic characteristics, it is desirable to apply a magnetic field during plating film formation, more preferably, to apply a magnetic field of 50 gauss or more. In order to obtain a smooth surface, the current density at the time of plating is 6.0 mA / cm.
^It is desirable to be ² or less.

[0025]

EXAMPLE A production test of a soft magnetic alloy plating thin film according to the present invention was conducted using a paddle stirring type plating bath having the shape shown in FIG. The plating bath is one in which a plating solution 5 is supplied into a plating tank 1 made of an acrylic resin.

In the plating layer 1, a cathode 2 on which a wafer to be plated is placed is disposed at a lower portion, and an anode 3 is disposed at an upper portion. The paddle 4 reciprocates in the plating tank 1. The magnetic field is applied in a direction perpendicular to the paddle motion, and its magnetic field strength is 500 Gauss. The temperature, pH and concentration of the plating solution 5 are controlled in the plating layer 1 and in the flow path thereof,
The solution supplied by the pump and overflowing is collected and returned to the plating tank again. The flow rate is adjusted by a flow control valve.

As the wafer, a glass substrate or a sintered body of alumina and titanium carbide is used, and a permalloy alloy film (thickness: 1000 mm) is used as a base film by a sputtering method when used.
Was formed.

The plating solution 5 contains 0.04 mol / l of cobalt sulfate heptahydrate and 0.04 mol / l of cobalt chloride hexahydrate.
mol / l, 0.115mol of nickel sulfate hexahydrate
/ L · nickel chloride hexahydrate 0.115 mol / l,
Contains 0.01 mol / l of iron sulfate heptahydrate. And p
10 mol / l boric acid as H buffer, 1.5 g / saccharin sodium to reduce stress of plating thin film
1. 0.1 g / l of sodium dodecyl sulfate was added as a surfactant for the plating film. Further, sodium molybdate, sodium tungstate, ammonium vanadate, and chromium (III) sulfate were added as additional elements. The pH of the plating solution was adjusted to 3.0 using hydrochloric acid. The temperature of the plating solution was set at 35 ± 0.1 ° C. using an electronic thermostat. The flow rate of the plating solution supplied to the plating tank was 4 liters per minute.

FIGS. 3 and 4 show the composition, specific resistance and saturation magnetic flux density of the plating film with respect to the concentration of molybdate ions in the plating solution. By adding hemolybdate ions to the plating solution, the Mo atomic% in the plating film was increased, and a remarkable effect on the increase in specific resistance was recognized.
The addition of hemolybdate ions in the plating solution monotonously reduced the saturation magnetic flux density. Similar effects of increasing the specific resistance were also observed when tungstate ions, vanadate ions, and chromium (III) ions were added.

In addition, Co ²⁺ , Fe ²⁺ , Ni
Table 1 shows the relationship between the film composition, the magnetostriction constant, and the saturation magnetic flux density in the plating films of various compositions obtained by changing the ²⁺ concentration. In the table, data showing characteristics unsuitable for use as a pole layer of a thin film magnetic head compatible with high recording density are underlined.

[0031]

[Table 1]

As is clear from Table 1, the magnetostriction constant increases as the Fe composition ratio in the film increases. In addition, F
e A soft magnetic plating thin film having a saturation magnetic flux density of 1.5 T or more and a low magnetostriction of 3 × 10 ⁻⁶ or less was obtained at a composition ratio of 5 at% or more and 10 at% or less.

[0033]

The plating thin film of the present invention has a high saturation magnetic flux density, is excellent in soft magnetic properties, has a high specific resistance, and is suitable as a magnetic material of a thin film magnetic head having excellent writing performance. This plated thin film can be manufactured by the manufacturing method of the present invention. As an additional effect, corrosion resistance is improved by mixing Mo, W, Cr, and V into the plating thin film. In addition, since this method performs plating under low current density conditions, it has excellent film thickness controllability and can control the magnetostriction constant by using the fact that the film composition changes by changing the current density. It is.

[Brief description of the drawings]

FIG. 1 is a diagram showing a distribution of a saturation magnetic flux density in a Co—Ni—Fe ternary alloy.

FIG. 2 is a paddle stirring type plating bath used in Examples.

FIG. 3 is a diagram showing a relationship between an additive element content and an additive ion concentration of a soft magnetic plating thin film manufactured according to an example of the present invention.

FIG. 4 is a graph showing the relationship between the content of additional elements, specific resistance, and saturation magnetic flux density of a soft magnetic plating thin film manufactured according to an example of the present invention.

[Explanation of symbols]

 1 Plating layer 2 Cathode 3 Anode 4 Paddle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tomohito Miyazaki 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka F-term within ReadWrite SMI Co., Ltd. 5D033 BA03 CA01 DA04 5D093 BD01 BD08 FA12 HA13 JA01 5E049 AA04 AA09 BA12 EB01 LC02 LC06

Claims (12)

[Claims] 1. A method for supplying divalent ions of Co, Ni and Fe to a plating solution by means of a salt containing divalent ions of Co, Ni and Fe, and adding molybdate ions and tungsten to the plating solution. At least one of acid ions, vanadate ions and chromium (III) ions is added, and the ion concentration of the added ions is 1 × 10 ⁻⁵ m
A method for producing a soft magnetic alloy plating thin film, wherein a soft magnetic alloy plating thin film is formed by performing electroplating in a plating solution of not less than 2 × 10 ⁻⁴ mol / l and not more than 2 × 10 ⁻⁴ mol / l. 2. The soft magnetic alloy according to claim 1, wherein the salt for supplying the divalent ions of Co, Ni, and Fe into the plating solution is a sulfate and / or a hydrochloride. Manufacturing method of plating thin film. 3. The method for producing a soft magnetic alloy plating thin film according to claim 1, wherein two or more kinds of additive ions are added. 4. The method according to claim 1, wherein the Co ion concentration in the plating solution is 0.05.
mol / 1 to 0.1mo1 / l, Ni ion concentration 0.2mo
More than 1/1 and less than 0.3mo1 / 1, Fe ion concentration is 0.01mo
4. The method for producing a soft magnetic alloy plating thin film according to claim 1, wherein the thickness is not less than 1/1 and not more than 0.3mo1 / 1. 5. The current density during electroplating is 6.0 mA / cm ^2.
The method for producing a soft magnetic alloy plating thin film according to claim 4, wherein: 6. The method for producing a soft magnetic alloy plating thin film according to claim 4, wherein the plating solution has a pH of 2 or more and 4 or less. 7. The method according to claim 4, wherein a magnetic field of 50 gauss or more is applied during electroplating. 8. A method for supplying each divalent ion of Co, Ni and Fe into a plating solution by a sulfate and / or a hydrochloride containing each divalent ion of Co, Ni and Fe;
At least two of molybdate ion, tungstate ion, vanadate ion and chromium (III) ion are added to the plating solution, and the ion concentration of the added ion is 1 × 10 ⁻⁵ mol / l or more and 2 × 10 ^-4 mol /
1 or less, Co ion concentration is 0.05 mol / 1 or more and 0.1 mol / l or less, Ni ion concentration is 0.2 mol / l or more and 0.3 mol / l or less, and Fe ion concentration is 0.01 mol / 1 or more and 0 mol / l or less. 3 mo1 / 1 or less, the pH of this plating solution is adjusted to 2 or more and 4 or less, and electroplating is performed while applying a magnetic field of a predetermined magnetic field strength in the plating solution to obtain a high saturation magnetic flux density and a high ratio. A method for producing a soft magnetic alloy plating thin film, comprising forming a soft magnetic alloy plating thin film having resistance. 9. A soft magnetic alloy plating thin film produced by the method for producing a soft magnetic alloy plating thin film according to claim 1, wherein Co, Ni, Fe is a main component and an additive element is provided. A soft magnetic alloy plating thin film containing at least one of Mo, W, V, and Cr in an amount of 1 atomic% to 5 atomic%. 10. The Co content in a plating film is 50 atomic%.
The soft magnetic alloy plating thin film according to claim 9, wherein the Fe content is not less than 90 atomic% and the Fe content is not less than 5 atomic% and not more than 10 atomic%. 11. A plating film having a specific resistance of 30 μΩ · cm or more, a saturation magnetic flux density of 1.5 T or more, and a magnetostriction constant of 3 × 10 ⁻⁶ or less. 2. The soft magnetic alloy plating thin film according to 1. 12. A thin-film magnetic head having an inductive head for performing magnetic recording on a magnetic recording medium by generating a magnetic field between the tip portions of upper and lower magnetic pole layers laminated one above another via a recording gap layer, A thin-film magnetic head, wherein one or both of the upper and lower magnetic pole layers is constituted by the soft magnetic alloy plated thin film according to claim 9, 10 or 11.