JP2002134318A - Magnetic thin film, method of manufacturing the same, and magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an FeCo plating film which is high in saturation magnetic flux density and kept free from pits and crackings, without adding a nonmagnetic metal concerning the magnetic thin film, a method of manufacturing the same, and a magnetic head. SOLUTION: The compositional weight ratio of Fe, Co, and Ni, contained in an FeCo plating film, indicates that it is included in a square region possessed of four apexes, represented by Fe80Co20, Fe40Co60, Fe40Co40Ni20, and Fe70Co10Ni20, and furthermore the compositional ratio of Ni is set at 1 wt.% or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic thin film, a method for manufacturing a magnetic thin film, and a magnetic head. high saturation magnetic flux density B _s magnetic thin film characterized by the arrangement for obtaining a plating film, a method of manufacturing a magnetic thin film used in the magnetic device, and to a magnetic head.

[0002]

2. Description of the Related Art In recent years, a hard disk, which is an external storage device of a computer, has been improved in recording density at an annual rate, the element size of a magnetic head has been reduced, and the recording medium has been increased in coercive force. There is a demand for a magnetic material having a sufficient writing capability even for a recording medium having a high coercive force.

[0003] In order to have sufficient writing ability against high coercive force of the recording medium, the upper magnetic pole cores constituting the inductive thin film magnetic head, or the upper magnetic pole core and the lower magnetic pole layer, the saturation magnetic flux density B _s It is necessary to use a material having a high magnetic flux density, and with the demand for higher recording density in recent years, it is considered that B _s ≧ 2.0T is essential in a portion where magnetic flux is most concentrated in the future.

Further, such an inductive thin film magnetic head is
The magnetic pole material is 3-4μ so that sufficient magnetic flux is generated at the tip.
m, and has a step, so that vacuum deposition techniques such as sputtering, which are often used as other magnetic material deposition methods, have low deposition rate efficiency and are effective. No etching method has been established. Therefore, conventionally, a magnetic pole is formed by an electroplating method which has high deposition efficiency and is excellent in selective film formation by using a resist frame.

[0005] A NiFe alloy thin film, that is, a permalloy is generally used as a magnetic pole material for writing in a conventional inductive type thin film magnetic head, because Ni ₈₀ Fe ₂₀ , That is, the saturation magnetic flux density of 80NiFe is B _s = 1.0T, and Ni ₅₀ Fe ₅₀ , ie,
The saturation magnetic flux density of 50NiFe is B _s = 1.5T.

[0006] However, NiFe is insufficient for the above-mentioned demand for a high saturation magnetic flux density, and as a magnetic material meeting the demand for a high saturation magnetic flux density, the highest saturation magnetic flux density B _s in a magnetic alloy is given. Are attracting attention. For bulk Fe ₆₀ Co ₄₀ , 2.45T is obtained (if necessary, R.F.
M. Bozorth, IEEE Press, p. 8
0, 1993).

When a magnetic material having such a high Fe composition ratio is to be formed, the concentration of Fe ions in the plating bath is reduced by the conventional N
It is necessary to sufficiently increase it compared with iFe or the like, and the amount of conversion of divalent Fe ions to trivalent Fe ions increases with an increase in the Fe composition ratio.

[0008] As described above, when trivalent Fe ions are present in the plating bath, a black-gray plating film which is generally brittle and has a large stress tends to be formed, and problems such as formation of pits and cracks in the plating film arise. In addition, the amount of increase of trivalent Fe ions in the plating bath cannot be ignored.

Therefore, in order to solve such a problem,
Pd, C in a plating bath containing Fe ions and Co ions
Attempts have been made to add metal ions such as u, Pt, Au, Ag, Ir, Rh, and Ru (if necessary, see JP-A-5-29172).

[0010]

However, when metal ions such as Pd and Cu are added to the plating bath, since these metals are non-magnetic metals, the saturation magnetic flux density of the plating film obtained is low. There is a problem of lowering.

Accordingly, an object of the present invention is to provide a FeCo-based plating film having a high saturation magnetic flux density in which pits and cracks are suppressed without adding a nonmagnetic metal.

[0012]

Here, means for solving the problems in the present invention will be described with reference to FIG.
FIG. 1 is a triangular composition diagram showing the composition range of FeCoNi of the present invention. See FIG. 1 In order to achieve the above object, the present invention provides a magnetic thin film in which the weight composition ratio of Fe, Co, and Ni is Fe ₈₀ C
o ₂₀ , Fe ₄₀ Co ₆₀ , Fe ₄₀ Co ₄₀ Ni ₂₀ , Fe ₇₀ Co
₁₀ Included in a quadrilateral region with Ni ₂₀ as the vertex, and Ni
The composition ratio is 1% by weight or more.

[0013] Although Ni is small magnetic moment compared with Fe or Co, since a magnetic element unlike Pd and Cu, when added as a third element, it minimizes the reduction in the saturation magnetic flux density B _s Can be suppressed.

Further, as is clear from the fact that Ni is widely used as a plating material, it is hard, has excellent chemical resistance and gloss, and has a feature that good plating can be easily obtained. It is possible to prevent pits and cracks that are likely to occur with the pits and cracks.

Therefore, such a large Fe composition ratio
In the FeCo alloy, the Ni composition ratio is 1% by weight or more.
By doing so, the surface roughness R_aIs small,
If R _a<200 nm or less, high saturation magnetic flux density, for example
If B_s≧ 2.0T, more preferably B_s≧ 2.2T
A magnetic thin film can be formed with good reproducibility. What
Here, the surface roughness R in this case_aIs JIS B0601
The arithmetic average roughness specified in the -1994 provisions,
When the surface roughness curve is y = f (x), the reference length L
Integrate the absolute value of y = f (x) over the
Surface roughness R in the present specification._aOr
Roughness R_aAre all JIS standard B0601-1994
It means the arithmetic average roughness specified in the regulations.

In this case, as the plating base layer, an FeCoNi film of the same system as the plating film and having a higher saturation magnetic flux density than NiFe, for example, Fe ₂₆ Co ₆₃ N
It is desirable to use the i _11, whereby it is possible to increase the saturation magnetic flux density of the entire upper magnetic pole core or the lower magnetic pole layer.

Further, according to the present invention, in the method for producing a magnetic thin film, the Fe ion / (Fe ion + Co ion) in the plating bath containing Fe ion, Co ion and Ni ion is 0.3 ≦ Fe ion / It is characterized in that a plating bath with (Fe ion + Co ion) <1.0 is used.

As described above, in order to obtain a FeCo-based magnetic thin film having a high saturation magnetic flux density, the Fe composition ratio needs to be 0.4 or more.
(Fe ion + Co ion) is defined as 0.3 ≦ Fe ion /
(Fe ion + Co ion).

In this case, [= C-SO ₂
-] An organic unsaturated compound not containing a structure and having a carbon triple bond or a carbon double bond, for example, 2-propyn-1-ol [PPO, molecular formula: HC≡C—CH ₂ —O
H], which allows the formation of a plating film having _a small surface roughness Ra.

According to the present invention, there is provided a magnetic head having at least an inductive thin film magnetic head, wherein the magnetic thin film is used for at least a part of an upper magnetic pole and a lower magnetic pole of the inductive thin film magnetic head.

As described above, by using the above magnetic thin film, the performance and cost of the magnetic head can be improved, and the performance of the magnetic storage device can be improved. In this case, the entirety of the upper magnetic pole and the lower magnetic pole may be formed, or either one of the magnetic poles may be formed, or at least the tip magnetic pole at the tip of the upper magnetic pole and the lower magnetic pole. It may be used as a core.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a magnetic thin film according to an embodiment of the present invention will be described with reference to FIGS. The plating apparatus used in the embodiment of the present invention includes:
Using a paddle device that is generally used as a conventional technology, the paddle device is used to perform electrolytic plating while stirring a plating bath, and the shape of the paddle, the distance from the substrate on which the magnetic thin film is deposited, that is, the distance from the cathode. The distance, the rotation speed, and the like are arbitrarily set as necessary, and are not particularly limited.

[0023] The plating bath used in the embodiment of the present invention, ferrous (FeSO ₄ · 7H ₂ O) sulfate, nickel sulfate _{(NiSO 4 · 6H 2 O)} , and cobalt sulfate (CoSO ₄ · 7H ₂ O) was changed to a metal ion concentration ratio in the plating bath of Fe ²⁺ : Co ²⁺ = 30: 70-10.
0: 0 and Ni ²⁺ : (Fe ²⁺ + Co ²⁺ + Ni ²⁺ )
= 0.01: 100 to 80: 100, and by adding boric acid at 30 g / liter,
The pH is adjusted to 2.0 to 3.5, for example, 2.5, the conductivity is adjusted by ammonium chloride, and sodium dodecyl sulfate as a surfactant is added to 0.2.
g / liter is used. Also, ascorbic acid is added as an antioxidant.

Electroplating is performed using such a plating bath. A Si substrate having a SiO ₂ film formed on the surface is used as a substrate, and a thickness of, for example, 10 nm is used to improve adhesion. After forming a Ti film by a sputtering method, a 50-nm-thick FeCoNi film is formed as a plating base layer by a sputtering method. Note that the weight composition ratio of the FeCoNi film is Fe ₂₆ Co ₆₃ Ni ₁₁ .

Next, at a temperature between room temperature and 40 ° C., for example, 30 ° C., at a plurality of current densities between 5 and 20 mA / cm ² , a DC magnetic field of 400 [Oe] or more, for example, 400
Electroplating was performed in a DC magnetic field of [Oe] to form a FeCoNi magnetic thin film on the underlying FeCoNi film.

FIG. 2 is an explanatory diagram of the dependency of the deposition rate of the plating film on the Ni composition ratio. In this case, Fe ²⁺ : Co ²⁺ = 50: 5.
The film formation rate was examined by changing the Ni ²⁺ concentration while ^keeping the Fe ²⁺ / Co ²⁺ ratio in the plating bath constant at 0 and the Ni composition ratio in the figure. The weight ratio is shown.

As is apparent from the figure, it is understood that the film formation rate increases with an increase in the Ni composition ratio. When the plating bath does not contain Ni ions, film formation is substantially impossible. Was. This is because Ni itself has a catalytic action,
By containing Ni ions in the plating bath,
This is considered to be because Ni itself easily precipitates and accelerates the plating reaction. When the Ni composition ratio was 1.0% by weight with respect to the weight of the plating film, a deposition rate of 0.05 μm / min was obtained.

[0028] Figure 3 Referring to FIG. 3 is an explanatory diagram of the Ni composition ratio dependence of surface roughness R _a of the plating film in the same film forming conditions as in FIG. As is clear from the figure, it is understood that the surface roughness _Ra decreases as the Ni composition ratio increases.

This is considered to be a result of suppressing cracks due to pits, which are likely to occur with an increase in Fe, because Ni originally has excellent gloss and has a feature that a good plating film can be obtained. In this connection, Ni composition ratio in 1.0% by weight relative to the weight of the plating film, a R _a ≒ 200 nm, at 5% by weight or more, stable to about R _a ≒ 10 nm.

[0030] See Figure 4. Figure 4 is a Ni composition ratio dependency of illustration of the saturation flux density B _s of the plating film in the same film forming conditions as in FIG. As can be seen, the saturation magnetic flux density B _s is understood to be reduced with increasing Ni composition ratio. In addition,
The open circles in the figure are the literature values when Ni = 0% by weight (if necessary, the above-mentioned RM Bozorth, IEEE
Press, p. 80, 1993) and B _s
≒ 2.4T.

This is because Ni is a magnetic element,
Is because the magnetic moment is smaller as compared with Fe or Co, therefore, with the increase of the Ni composition ratio, when it decreases the saturation magnetic flux density B _s, the addition of nonmagnetic element such as Cu or Pd as in the prior art compared to it it is possible to suppress the reduction of the saturation magnetic flux density B _s. By the way, if Ni ≒ 20% by weight,
B _s ≒ 2.0T, and although there is a measurement error, the saturation magnetic flux density of B _s ≒ 2.2T can be maintained until the Ni composition ratio becomes 15% by weight.

Referring to FIG. 5, FIG.²⁺: Co²⁺= 50: 5
0 and Fe in plating bath ²⁺/ Co²⁺State with constant ratio
And Ni²⁺Concentration, i.e., NiSO_FourWhen the concentration is changed
Of the amount (% by weight) of Ni deposited in the plating film
And Ni²⁺The concentration is NiSO_Four/ (FeSO_Four+ C
oSO_Four+ NiSO_Four) In molar ratio.

As described above, when NiSO ₄ was not added to the plating bath, film formation was impossible, but as is apparent from the figure, NiSO ₄ / (FeSO ₄ + CoSO _4
4 + NiSO ₄ ) = 0.01 mol%
It is understood that when O ₄ is added, the amount of Ni deposited in the plating film is about 1.0% by weight.

FIG. 6 is a graph showing the relationship between the Fe / Co precipitation amount ratio of FeSO ₄ and CoSO.
FIG. ₄ is a graph showing the concentration ratio dependency of Ni in the plating bath;
With the SO ₄ concentration kept constant at 0.01 mol%, Fe
It is a result of examining the ratio of the amount of Fe and Co deposited in the plating film when the SO ₄ / CoSO ₄ ratio is changed. The concentration ratio in the plating bath is FeSO ₄ / (FeSO ₄ + C
oSO ₄ ) in mol%, and the precipitation amount ratio is Fe / (Fe
+ Co) in% by weight.

As is apparent from the figure, FeSO ₄ / (F
With the increase of eSO ₄ + CoSO ₄ ), Fe / (Fe
+ Co) is understood to increase almost linearly, and if the trend is extrapolated, the upper limit of the Fe composition ratio is 80%.

On the other hand, although the lower limit of the Fe composition ratio does not exist under the film forming conditions, the Fe composition ratio is increased in order to obtain a magnetic film having a high saturation magnetic flux density.
The composition ratio is desirably 40% or more, and particularly, 50% or more.
% Is desirable. By the way, when the Fe composition ratio is 40
%, If there is a measurement error, as shown in FIG. 6, FeSO ₄ / (FeSO ₄ + CoSO
It is understood that ₄ ) needs to be 30 mol% or more.

If the above are considered comprehensively, F
increasing the film formation rate by the addition of Ni to eCo based plating bath, and, it is possible to reduce the surface roughness R _a, as the Ni composition ratio in the plating film, 1.0% by weight or more, more Preferably, the content is 2.0% by weight or more. In order to obtain excellent characteristics with respect to all of the film formation rate, the surface roughness R _a , and the saturation magnetic flux density B _s ,
It is desirably 5.0% by weight or more.

On the other hand, as apparent from FIG. 4, in order to achieve a high saturation magnetic flux density, it is desirable that the Ni composition ratio is small, and an original high saturation magnetic flux density film of B _s ≧ 2.0T is obtained. if considering the purpose, Ni composition ratio is preferably set to 20% by weight or less, in order to B _s ≒ 2.2 T, it is desirable that the 15 wt% or less.

Further, as is apparent from FIG.
(Fe + Co) is also limited, and as described above, the composition ratio of Fe is desirably 40% by weight to 80% by weight.

Referring again to FIG. 1, FIG. 1 shows a preferable composition range summarizing the above, and the composition range is defined as Fe ₈₀ Co ₂₀ , Fe ₄₀ Co ₆₀ , and Fe ₄₀
It is understood that a region that is included in a quadrangular region having Co ₄₀ Ni ₂₀ and Fe ₇₀ Co ₁₀ Ni ₂₀ as vertices and has a Ni composition ratio of 1% by weight or more is preferable.

Therefore, by using a magnetic thin film satisfying the above conditions as at least a part of an inductive thin film magnetic head, recording on a high coercive force magnetic recording medium becomes possible. For example, in a U-shaped inductive thin-film magnetic head in which upper and lower magnetic pole layers are coupled at the center of a write coil, the inside becomes the magnetic thin film of the present invention.
It may be constituted by a layered structure, or in the case of a tip type magnetic pole provided with narrow protrusions vertically opposed to each other at the tip portions of the upper and lower magnetic pole layers to reduce the core width, that is, at the light pole. In this case, the protrusions may be formed of the magnetic thin film of the present invention, thereby enabling recording on a high coercive force magnetic medium and achieving an improvement in recording density.

Although the embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the embodiment, and various modifications are possible. For example, in the above embodiment, ammonium chloride is used as a reagent for increasing the conductivity of the plating bath. However, the reagent is not limited to ammonium chloride, and sodium chloride or ammonium sulfate may be added. Things.

[0043] Further, in the above embodiment, the organic additive such as saccharin sodium, i.e., although using a plating bath containing no primary brightener, in order to reduce the surface roughness R _a, of saccharin sodium Organic additives may be added.

The primary brightener in Ni plating is a material which does not exhibit gloss alone or gives a semi-gloss, but when used in combination with a secondary brightener which will be described later, excellent gloss is obtained. And the primary brightener has an effect of reducing the internal stress given by the secondary brightener. Generally, [C = C-S
O _2] and [C = C-C-SO _2] a sulfur compound having a double bond such as a number, for example, 1,3,6-naphthalene sodium trisulfonate corresponds.

[0045] Further, as another method of reducing surface roughness R _a, [= C-SO ₂ -] is an organic additive which does not have the structure of, and, of carbon triple bond or carbon double bond structure Or a secondary brightener may be added. By the addition of such an organic unsaturated compound, it is possible to reduce the surface roughness R _a, it can be obtained an excellent magnetic thin film in corrosion resistance.

As an organic additive, [= C—SO ₂
-] The secondary brightener containing no structure and containing a carbon triple bond [C≡C] includes 2-propyn-1-ol [P
PO, molecular formula: HC≡C—CH ₂ —OH] is preferred, but is not limited to 2-propyn-1-ol, and is the same as 2-propyn-1-ol [= C—SO
₂ -] structure free of, and a secondary brightener containing a carbon triple bond [C≡C], for example, using 2-butyn-1-ol or 2-butyne-1,4-diol Is also good.

Furthermore, a secondary brightener containing no [= C-SO _2- ] structure and containing a carbon double bond [C = C], such as sulfonbenzaldehyde or coumarin derivative, is used. Is also good.

In the above embodiment, ascorbic acid as an antioxidant is added to the plating bath. However, when it is added, the deposition rate of the plating film tends to decrease. Need not always be added.

In the above embodiment, the FeCoNi film, which is similar to the plating film, is used as the plating base layer in order to increase the saturation magnetic flux density.
The invention is not limited to the CoNi film, and a NiFe film may be used.

In the above description of the embodiment, it is assumed that the magnetic head is used for the upper magnetic pole layer or the lower magnetic pole layer of the induction type thin film magnetic head. However, the present invention is limited to such an application. Instead, it may be used as a magnetic shield layer above and below a read-only single MR head, and furthermore, above and below a composite thin film magnetic head in which an inductive thin film magnetic head and an MR head are stacked. May be used as the whole or a part of the magnetic shield layer and the upper and lower magnetic pole layers.

Further, the present invention is not limited to the magnetic material used for the magnetic head, but can be used, for example, as a magnetic shield material or a magnetic transformer in a magnetic measuring device or the like.

Here, the detailed features of the present invention will be described. (Supplementary Note 1) The weight composition ratio of Fe, Co, and Ni is Fe ₈₀
Co ₂₀ , Fe ₄₀ Co ₆₀ , Fe ₄₀ Co ₄₀ Ni ₂₀ , Fe ₇₀ C
o ₁₀ Ni ₂₀ contained in a quadrilateral region having a vertex and N
i. A magnetic thin film having a composition ratio of 1% by weight or more. (Supplementary Note 2) The saturation magnetic flux density of the magnetic thin film is 2.0 T
The magnetic thin film according to claim 1, characterized in that: (Supplementary Note 3) As the plating base layer of the magnetic thin film, F
Appendix 1 or 2 wherein an eCoNi film is used.
3. The magnetic thin film according to 1. (Supplementary Note 4) In the method of manufacturing a magnetic thin film according to Supplementary Note 1, Fe ions in a plating bath containing Fe ions, Co ions, and Ni ions / (Fe ions + Co ions).
Is 0.3 ≦ Fe ion / (Fe ion + Co ion)
A method for producing a magnetic thin film, comprising using a plating bath having a value of <1.0. (Supplementary note 5) The method for producing a magnetic thin film according to Supplementary note 4, wherein the Ni ion concentration in the plating bath is 0.01% or more based on the total metal ion concentration. During (Supplementary Note 6) The plating bath [= C-SO ₂ -] does not contain the structure, and, Appendix 4 or, characterized in that contains an organic unsaturated compound having a carbon triple bond or carbon double bond 6. The method for producing a magnetic thin film according to 5. (Supplementary note 7) The method for producing a magnetic thin film according to supplementary note 6, wherein the organic unsaturated compound having a carbon triple bond or a carbon double bond is 2-propyn-1-ol. (Supplementary Note 8) In the magnetic head including at least the inductive thin film magnetic head, the magnetic thin film according to any one of Supplementary notes 1 to 3 is used for at least a part of an upper magnetic pole and a lower magnetic pole of the inductive thin film magnetic head. A magnetic head, characterized in that: (Supplementary note 9) A magnetic storage device comprising the magnetic head according to supplementary note 8.

[0053]

According to the present invention, when a magnetic thin film having a large Fe composition ratio and a high saturation magnetic flux density is formed, the plating bath contains N
By adding i-ions, it is possible to obtain a good plating film without pits and cracks while minimizing the decrease in the saturation magnetic flux density, thereby increasing the frequency of the thin-film magnetic head and increasing the recording density. And ultimately,
This greatly contributes to the spread of magnetic storage devices and the like incorporating high-performance HDD devices and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a preferable composition range of a magnetic thin film according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the dependency of the deposition rate of a plating film on the Ni composition ratio in an embodiment of the present invention.

FIG. 3 is an explanatory diagram of Ni composition ratio dependence of surface roughness Ra of _a plating film in the embodiment of the present invention.

4 is a Ni composition ratio dependency of illustration of the saturation flux density B _s of the plating film in the embodiment of the present invention.

FIG. 5 shows the Ni deposition amount of Ni according to the embodiment of the present invention.
FIG. ₄ is an explanatory diagram of SO ₄ content dependency.

FIG. 6 is an explanatory diagram of the dependency of Fe and Co deposition amounts on the FeSO ₄ and CoSO ₄ concentration ratio in the embodiment of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 41/26 H01F 41/26 (72) Inventor Yuko Miyake 4-1-1 Kamedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture No.1 Fujitsu Limited F term (reference) 4K023 AB12 AB13 BA06 CB05 4K024 AA14 AB01 AB15 BA11 BB14 CA01 CA02 5D033 BA03 CA01 DA04 5E049 AA01 BA12 GC01 LC02

Claims (5)

[Claims] The weight composition ratio of Fe, Co, and Ni is Fe
₈₀ Co ₂₀ , Fe ₄₀ Co ₆₀ , Fe ₄₀ Co ₄₀ Ni ₂₀ , Fe ₇₀
Included in a quadrangular region having Co ₁₀ Ni ₂₀ as the apex, and
A magnetic thin film having a Ni composition ratio of 1% by weight or more. 2. The method for producing a magnetic thin film according to claim 1, wherein the ratio of Fe ion / (Fe ion + Co ion) in the plating bath containing Fe ion, Co ion, and Ni ion is 0.3 ≦ Fe ion. A method for producing a magnetic thin film, comprising using a plating bath in which / (Fe ion + Co ion) <1.0. 3. The method according to claim 3, wherein [= C-SO _2- ]
The method for producing a magnetic thin film according to claim 2, wherein an organic unsaturated compound having no structure and having a carbon triple bond or a carbon double bond is contained. 4. The method according to claim 3, wherein the organic unsaturated compound having a carbon triple bond or a carbon double bond is 2-propyn-1-ol. 5. A magnetic head having at least an inductive thin film magnetic head, wherein the magnetic thin film according to claim 1 is used for at least a part of an upper magnetic pole and a lower magnetic pole of the inductive thin film magnetic head. Magnetic head.