JP2897485B2 - Soft magnetic thin film and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic thin film for a thin film magnetic head for high density recording and a method for manufacturing the same.

[0002]

2. Description of the Related Art Permalloy magnetic thin films formed by electroplating have been most commonly used as a soft magnetic layer of a thin film magnetic core of a high-density magnetic recording thin film magnetic head for an HDD. The coercive force (Hc) of magnetic recording media has increased due to the technical demands for density. According to the method of forming a thin-film magnetic core pattern by electroplating, a magnetic film can be formed in a desired shape directly from the underlying electrode layer through the window of the patterned photoresist layer. From this, the cross-sectional shape of the magnetic film pattern edge can maintain a vertically steep shape compared to the case where the magnetic film is formed on the entire substrate by the vapor deposition method and the magnetic core pattern is formed by etching, so that the magnetic core particularly There are process advantages such as control of pattern accuracy such as track width control, and keeping the thickness of the inclined portion of the magnetic core layer as flat.

Further, there is also a material advantage that soft magnetic characteristics such as initial magnetic permeability can be basically obtained without heat treatment for the magnetic film. However, the characteristics of the saturation magnetic flux density (Bs) of the permalloy alloy material and Bs = 0.1 T have become insufficient for the recording efficiency of the high coercive force medium as described above. In addition, in order to stably control the magnetic domain structure of the magnetic core pattern in order to stabilize the output and noise of the thin film head, the anisotropic magnetic field (Hk = 240 to 4
The size of (00 A / m) is not always appropriate.

[0004] Accordingly, high permalloy or higher can be produced by the electroplating method having the advantages as described above.
There has been a demand for a magnetic film having a practical initial magnetic permeability, which is a Bs, high Hk thin film and has zero saturation magnetostriction like permalloy, and a method of manufacturing the same by electroplating.

[0005]

As described above, only a permalloy alloy is known as a soft magnetic film having practical characteristics of zero saturation magnetostriction which can be formed by an electroplating method used as a magnetic core magnetic layer as described above. A new alloy soft magnetic thin film of zero magnetostriction with a high saturation magnetic flux density replacing permalloy for thin film heads for high density recording, which requires high recording capacity, narrow track width, and stable output for high coercivity media It has been desired to prepare a conventional thin-film head core film by an electroplating method having the above-described manufacturing method advantages.

[0006]

According to the present invention, there is provided an electroplating method comprising the steps of:
CoxFeyCrz is a ternary alloy thin film made of chromium.
When a soft magnetic thin film material of x ≧ 80, 19 ≧ y> 0, 9 ≧ Z> 0 is used as a soft magnetic thin film for a thin film head core, at least Fe2 +, Co2 +, Cr3 +
R (Co2 +) = [Co2 +] / [Fe2 +] + [Co2 +] + [Cr3 +] R (Fe2 +) = [Fe2 +] / [Fe2 +] + [Co2 +] + [Cr3 +] R (Cr3 +) = [Cr3 +] / [Fe2 +] + [Co2 +] + [Cr3 +]
Under the condition that 0.90 ≧ R (Co2 +) ≧ 0.55 0.15 ≧ R (Fe2 +) ≧ 0.055 0.35 ≧ R (Cr3 +) ≧ 0.08, the current density is 50 mA / c at the DC plating current.
or using m ² or more, or up to the plating current density pulse plating current to the cathode as 50 mA / cm ² or more CoFeCr3
A method for producing a soft magnetic thin film, which is to obtain an original alloy thin film, is a means for solving the above problems.

[0007]

As described above, a soft magnetic thin film material having high saturation magnetic flux density and zero magnetostriction is desired as a magnetic core pattern of a thin film magnetic head, but it has characteristics similar to those of conventional permalloy materials. Co-Fe alloy was one of the materials to have. The Co-Fe alloy has a face-centered cubic structure with a saturation magnetostriction of zero at around ₁₀ atomic% of Co ₉₀ Fe and a saturation magnetic flux density of 1.9.
It has a value nearly twice that of T and Permalloy, and an anisotropic magnetic field
(Hk) has also been known to have a value of about 800 A / m, but especially when thinned, near the Co90Fe10 composition is also near the boundary composition in the equilibrium state of the face-centered cubic structure and the body-centered cubic structure Therefore, a thin film having a composition near this composition is often formed as a composite of a face-centered and body-centered cubic structure, and a thin film having a high initial permeability having good soft magnetic properties based on a homogeneous structure is obtained. I couldn't get it before. According to the heat treatment, the whole can be stabilized to a face-centered cubic structure.
Since the heat treatment at about 00 ° C. is the upper limit, this was too low for the heat treatment temperature and the effect could not be expected. In the Co-Fe-Cr ternary alloy soft magnetic thin film prepared by the electrodeposition method of the present invention, Cr
Can be obtained as a homogeneous face-centered cubic single-phase structure, resulting in a heterogeneous film structure near the Co ₉₀ Fe ₁₀ composition.
It was considered that a high initial magnetic permeability higher than that of the Co-Fe binary system was obtained. Co-Fe2 even in a ternary system with the addition of several percent Cr
As with the original system, the fact that zero magnetostriction is realized is considered to be due to the fact that zero magnetostriction is a characteristic derived from the face-centered cubic structure.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples will be described below in detail.

FIG. 1 shows an electrodeposition film composition and electrodeposition obtained by changing the current density conditions using the electrodeposition baths and conditions shown in Table 1 as a first embodiment of the present invention. 9 shows a relationship with a current density condition. It can be seen that a Co—Fe—Cr ternary alloy film having a wide range of composition as shown in FIG. 1 can be obtained at a current density of at least 50 mA / cm ² using the same bath shown in Table 1. . Conversely, Cr at 50 mA / cm ² or less
Did not alloy at all.

[0010]

[Table 1]

As shown in Table 2, Co2 +, Fe2 +, Cr
R (Co2 +) = [Co2 +] / [Fe2 +] + [Co2 +] + [Cr3 +] R (Fe2 +) = [Fe2 +] / [Fe2 +] + [Co2 +] + [Cr3 +] R ( (Cr3 +) = [Cr3 +] / [Fe2 +] + [Co2 +] + [Cr3 +]
When 0.90 ≥ R (Co2 +) ≥ 0.55 0.15 ≥ R (Fe2 +) ≥ 0.055 0.35 ≥ R (Cr3 +) ≥ 0.088, the DC or pulsed electrodeposition current density is 10
The composition of the thin film obtained under a constant condition of 0 mA / cm ² is C
It was found that a ternary alloy thin film satisfying x ≧ 80, 19 ≧ y> 0, and 9 ≧ Z> 0 was obtained as represented by oxFeyCrz. (In the case of using a pulse current, a pulse current having a frequency of 10 Hz and a duty ratio of 1: 1 was used.)

[0012]

[Table 2]

At this time, the alloy electrodeposited film is given a uniaxial magnetic anisotropy by being formed in a static magnetic field, so that the coercive force (Hc) in the direction of the hard axis as shown in (Table 2). Is 3
Films having excellent soft magnetic properties including those having a thickness of not more than 00 A / m were obtained. Further, as shown in (Table 2), one having a saturation magnetostriction close to zero was obtained.

[0014]

As described above, the thin film magnetic head corresponding to the high coercive force medium can be manufactured with the same accuracy as the conventional one by the soft magnetic film and the method of manufacturing the same according to the present invention. The obtained effect is expected.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the film composition of an electrodeposited film and the electrodeposition current density used for electrodeposition when using the electrodeposition bath and electrodeposition conditions shown in Table 1.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01F 10/16 H01F 41/26

Claims (2)

(57) [Claims] 1. A thin film produced by an electroplating method, which is a ternary alloy composed of cobalt, iron and chromium, where x ≧ 80, 19 ≧ y> 0, 9 when represented by CoxFeyCrz in each atomic%. ≧
A soft magnetic thin film, wherein Z> 0. 2. A plating bath in which at least each metal ion of Fe2 +, Co2 +, and Cr3 + coexists, and the ratio of each ion concentration in the bath is R (Co2 +) = [Co2 +] / [Fe2 +] + [Co2 +] + [ Cr3 +] R (Fe2 +) = [Fe2 +] / [Fe2 +] + [Co2 +] + [Cr3 +] R (Cr3 +) = [Cr3 +] / [Fe2 +] + [Co2 +] + [Cr3 +]
When 0.90 ≧ R (Co2 +) ≧ 0.55 0.15 ≧ R (Fe2 +) ≧ 0.055 0.35 ≧ R (Cr3 +) ≧ 0.08, use a DC plating current with a current density of 50 mA / cm ² or more, or use a pulse plating current A method for producing a soft magnetic thin film, wherein a CoFeCr ternary alloy thin film is obtained on a cathode with a plating current density of 50 mA / cm ² or more.