JPH1116120A - Thin-film magnetic head and magnetic recording and reproduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the recording magnetic field intensity at a high frequency from lowering without the execution of a heat treatment after plating by forming two-layered films laminated with a magnetic layer having a high saturation magnetic flux density and a magnetic layer having a low magnetostriction constant by changing current density from a plating bath having bivalent Ni and Fe metal ions. SOLUTION: The lower magnetic film 12 consisting of a 'Permalloy (R)' thin-film contg. nitrogen, a magnetic gap layer 13 consisting of Al2 O3 , an insulating film 14 consisting of a photoresist, a coil 15 consisting of Cu and an insulating film 16 are successively formed on a substrate 11. Next, the upper magnetic films 17 of the two-layered films consisting of the magnetic layer having the high saturation magnetic flux density and the magnetic layer having the low magnetostriction constant are formed by changing the current density by using a flame plating method on the insulating film 16. The protective film 18 consisting of the Al2 O3 is formed thereon. As a result, the magnetic domain structure may be optimized even without the execution of the heat treatment and the max. recording frequency may be made >=100 MHz.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head and a magnetic recording / reproducing apparatus compatible with a high magnetic recording density.

[0002]

2. Description of the Related Art With the increase in recording density of magnetic disk devices, a thin film magnetic head capable of recording on a medium having a high coercive force has been required. For that purpose, it is necessary to use a material having a high saturation magnetic flux density and excellent high-frequency characteristics as a core material of the magnetic head.

At present, the core of the magnetic head is manufactured by a frame plating method. As the magnetic core material produced by the plating method, permalloy (78 wt% Ni-Fe alloy) is known. However, this material has a saturation magnetic flux density of 1.
0T and low. In addition, as a core material produced by a plating method, for example, as shown in JP-A-62-256989 or JP-A-6-5423, Co-Ni-Fe
Alloys or Co-Fe alloys. These materials have a high saturation magnetic flux density of 1.5 T or more, but have a problem that the eddy current loss at high frequencies is large and the recording magnetic field strength is reduced because the electric resistivity is as low as 20 μΩcm.

As disclosed in Japanese Patent Application No. Hei 7-16666, there is a 40-60 wt% Ni-Fe alloy which has a high saturation magnetic flux density of 1.4 T or more and is produced by plating.
Since this material has a high electrical resistivity of about 40 μΩcm,
Eddy current loss is suppressed, and the recording magnetic field intensity does not decrease at high frequencies. However, when the core has a magnetostriction constant as high as +30/10 ⁷ or more, the magnetic domain structure is disturbed by stress, and heat treatment is required after the formation of the magnetic core.

Also, Electrochemistry, Vol. 62, No. 5, 45
"Preparation of Soft Magnetic FeP Films b" on page 3
y Means of Electrodeposition Method), the FeP film has a high saturation magnetic flux density of 1.4T,
In addition, since the electrical resistivity is as high as 160 μΩcm, eddy current loss at high frequencies is suppressed. However, the magnetostriction constant is very high at +10 to 20/10 ^6, and there is a problem in corrosion resistance.

Further, Journal of the Japan Society of Applied Magnetics, No. 20, 43
"Soft magnetic FeP / M (M
= Ni, CoP) / FeP As shown in the control of the magnetostriction of the laminated film, there is an example in which a multilayer film is formed from two plating baths.
However, in this case, an oxide layer may be formed at the interface, and care must be taken to stabilize the characteristics of the film.

[0007]

A magnetic disk drive having a high magnetic recording density has a high saturation magnetic flux density,
In addition, it is necessary to use a thin-film magnetic head using a material that does not reduce the recording magnetic field strength at high frequencies. The 40-60 wt% Ni-Fe alloy produced by plating is
It has a high saturation magnetic flux density of 1.4 T or more and a high electrical resistivity of about 40 μΩcm, and the recording magnetic field strength at high frequencies does not decrease. However, since the magnetostriction was positively large, it was necessary to have a heat treatment after plating.

An object of the present invention is to provide a thin-film head which solves the above-mentioned problems of the thin-film magnetic head. Another object of the present invention is to provide a magnetic recording / reproducing apparatus using the same.

[0009]

Means for Solving the Problems The present inventors have conducted a sincere study on a magnetic core material in a thin-film magnetic head, and as a result, have changed the current density from a plating bath containing divalent Ni and Fe metal ions. By stacking a magnetic layer having a high saturation magnetic flux density and a magnetic layer having a low magnetostriction constant,
A thin film magnetic head having a layer film formed thereon and using the same as a magnetic core has found that the recording magnetic field intensity does not decrease even at a high frequency of 100 MHz, and has completed the present invention.

That is, the divalent Ni and Fe metal ion concentration ranges are 5 to 20 g / l and 1.7 to 20 g, respectively.
/ L, and the metal ion concentration ratio between Ni and Fe is 1 to 1.
3, a Ni—Fe—S magnetic layer having a high saturation magnetic flux density and a Ni having a low magnetostriction constant are obtained by changing the current density from the plating bath to which thiourea is added as a stress relaxation agent. Forming a two-layer film of an Fe-S magnetic layer; The magnetic domain structure of the magnetic core using the plated two-layer film is optimized without heat treatment, and the thin film magnetic head using the two-layer film has a thickness of the magnetic layer having a high saturation magnetic flux density of 0.5. When formed to a thickness of at least μm, the recording magnetic field intensity does not decrease even at a high frequency of 100 MHz.

The divalent Ni and Fe metal ion concentration ranges are 5 to 20 g / l and 0.5 to 2.7 g / l, respectively.
And a plating bath composed of a solvent having a metal ion concentration ratio of Ni and Fe of 6 to 8 in a total amount of 0.7 g / l.
By changing the current density from a plating bath containing at least one of the following Cr, Mo, and W metal ions, a two-layer film of a magnetic layer having a high saturation magnetic flux density and a magnetic layer having a low magnetostriction constant is formed. The magnetic domain structure of the magnetic core using the plated two-layer film can be optimized without heat treatment.

Further, since the present invention is formed from the same plating bath, there is no possibility that an oxide film or the like is formed at the interface, and a good film can be easily produced.

Further, by using a magnetic head in which the above-mentioned thin film magnetic head and a multilayer magnetoresistive element are combined, a magnetic recording / reproducing apparatus having a high magnetic recording density can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.
This will be described more specifically with reference to the figures and tables.

[Example 1] A substrate was made of Ni-Fe (80n
Using a glass substrate sputtered with m) / Cr (30 nm), a film was formed from a plating bath shown in Table 1 in a DC magnetic field of 190 Oe.

[0016]

[Table 1]

Here, the bath temperature was 30 ° C., the pH was 3.0, and the current density was changed. FIG. 1 shows the composition change of the plating film when the current density is changed.

As shown in FIG. 1, as the current density increases, the Ni composition and the S composition decrease, and the Fe composition increases. 2 and 3 show the electrical resistivity ρ,
The relationship between the magnetostriction constant λs, the saturation magnetic flux density Bs, and the current density is shown.

As shown in the figure, the electrical resistivity is almost constant at 60 μΩcm regardless of the current density. The magnetostriction constant and the saturation magnetic flux density depend on the Ni—Fe composition, and increase as the current density increases. As a result, the current density was 23 m
When the current density is A / cm ² , the saturation magnetic flux density becomes high, and the magnetostriction becomes almost zero when the current density is around 7 mA / cm ² . As a result,
By changing the current density, a two-layer plating film in which a magnetic layer having a high saturation magnetic flux density and a magnetic layer having a low magnetostriction are laminated can be formed. Next, the current density was changed to keep the thickness of the magnetic layer constant at 3.0 μm, and the thickness ratio of the two-layer film was changed. FIG. 4 shows the relationship between the magnetostriction constant of the entire film and the thickness of the magnetic layer having a high saturation magnetic flux density. Thus, the magnetostriction constant is determined by the thickness ratio of the two-layer film. These film frame plating on the magnetic core shape was evaluated for magnetic domain structure, magnetostriction constant in Tasu20/10 ⁷ following areas, magnetization without heat treatment direction in the track width direction, it is optimized.

Next, a magnetic head using the two-layer film was manufactured. FIG. 5 shows a cross section of the thin-film magnetic head. Substrate 11
A ceramic substrate whose surface was sufficiently polished and cleaned was used. A 2.8 μm thick nitrogen-containing permalloy (78 wt% Ni) was formed on the substrate 11 as the lower magnetic film 12.
-Fe) A thin film was produced by a high frequency sputtering method. The magnetic characteristics of the Ni-Fe film containing nitrogen include a coercive force of 0.5 Oe, a saturation magnetic flux density of 1.0 T and a magnetostriction constant of -1.
It was 0/10 ⁷ .

After patterning the lower magnetic film 12 into a predetermined shape by ion milling, a magnetic gap film 13 made of Al ₂ O ₃ was sputtered and patterned by ion milling.

Next, an insulating film 14 made of a photoresist was patterned into a predetermined shape by coating, exposing, developing and heat-treating. On the insulating film 14, a coil 15 made of Cu
Was formed by plating, and an insulating film 16 was formed and patterned into a predetermined shape. An upper magnetic film 17 having a thickness of 3.0 μm was formed on the insulating film 16 by changing the current density using a frame plating method.

The upper magnetic film has a current density of 23 A
/ Cm ² to form a magnetic layer having a high saturation magnetic flux density,
The current density was set to 7 A / cm ² to form a two-layer film having a magnetic layer having a low magnetostriction constant. No heat treatment of the upper core was performed. Finally, a protective film 18 made of Al ₂ O ₃ was formed.

Using the above thin film magnetic head, 70 MHz
FIG. 6 shows the result of examining the relationship between the overwrite characteristics at the time and the thickness of the magnetic layer having a high saturation magnetic flux density.

Here, the head having a thickness of 2.0 μm is subjected to heat treatment because the magnetic domain structure has not been optimized.
The magnetic recording medium has a residual magnetic flux density of 2500 Oe, Co-
A material made of a Cr-Pt alloy was used. The track width of the magnetic head was 2.0 μm. As shown in the figure, the thickness of the magnetic layer having a high saturation magnetic flux density is substantially constant at 0.5 μm or more, and the thickness of the magnetic layer having a high saturation magnetic flux density is 0.5 μm.
5 μm is sufficient.

FIG. 7 shows the frequency dependence of the recording magnetic field strength of a magnetic head in which the thickness of the magnetic layer having a high saturation magnetic flux density is 0.5 μm. For comparison, the upper core is made of 46 watts having a saturation magnetic flux density of 1.6 T and an electric resistivity of 45 μΩcm.
A magnetic head that has been heat-treated using a t% Ni—Fe single layer film is shown.

As shown in the figure, the thin film magnetic head of the present invention
It has a high recording magnetic field even at a high frequency of 100 MHz without heat treatment. This is considered to be the effect of reducing the magnetostriction and the effect of increasing the electrical resistivity of the film to 60 μΩcm.

In this embodiment, the result in which only the upper magnetic film is a two-layer film has been described. However, a higher effect can be obtained by similarly forming the lower magnetic film as a two-layer film.

Example 2 A substrate was made of Ni--Fe (80 n
m) / Cr (30 nm) was sputtered from a plating bath shown in Table 2 in a DC magnetic field of 190 Oe to form a film.

[0030]

[Table 2]

Here, the bath temperature was 30 ° C., the pH was 3.0, and the current density was changed. FIG. 8 shows the relationship between the composition of the plating film and the current density. 9 and 10 show the relationship between magnetostriction λs, electrical resistivity ρ, saturation magnetic flux density Bs, and current density.

As shown in FIG. 8, the plating film composition changes by changing the current density. Accordingly, various characteristics of the film change as shown in FIGS. As a result, by changing the current density, a two-layer film in which a magnetic layer having a high saturation magnetic flux density and a magnetic layer having a low magnetostriction are laminated can be formed.
When the current density is 10 mA / cm ² and the saturation magnetic flux density is 1.6 T
And a magnetic layer with a high current density of 0.5 μm.
When a magnetic layer having a magnetostriction constant of almost zero and a magnetic layer of 2.5 μm was formed at 5 mA / cm ² , a two-layer film was formed by a frame plating method, and the magnetic domain structure was evaluated. Was done.

In this embodiment, Cr is used as the metal to be added to Ni--Fe, but the same effect can be obtained by using Mo and W. These two-layer films have low magnetostriction constants,
Even without heat treatment, the domain structure is optimized. Also,
The electric resistivity is 45-50 μΩcm and 46 wt% Ni-Fe
Since the thickness is equal to or higher than that of the single-layer film, it is possible to cope with a high recording frequency without heat treatment of the upper magnetic film.

[Embodiment 3] Using the thin-film magnetic head shown in Embodiment 1, a recording / reproducing separation type head was manufactured. The structure of the magnetic head is shown below. FIG. 11 is a perspective view when a part of the magnetic head is cut.

The magnetoresistive film 21 is formed of the shield layers 22 and 2
The portion sandwiched between 3 functions as a reproducing head. The shield layer 23 also functions as the lower magnetic pole of the recording head, and the portion of the shield layer 23 and the upper magnetic pole 25 sandwiching the coil 24 functions as a recording head. This recording head is the thin-film magnetic head described in the first embodiment. In addition, the electrode 27
A material having a multilayer structure of / Cu / Cr was used. Hereinafter, a method for manufacturing this head will be described.

A sintered body mainly composed of Al ₂ O ₃ .TiC was used as a substrate 26 for the slider. Permalloy containing nitrogen formed by a sputtering method was used for the shield layers 22 and 23. The thickness of each magnetic film was as follows. The upper and lower shield layers 22 and 23 were 2.0 μm, the upper pole 25 was 3.0 μm, and Al ₂ O ₃ formed by sputtering was used as a gap material between the layers. The thickness of the gap layer is
The thickness was 0.2 μm between the shield layer and the magnetoresistive element, and 0.4 μm between the recording magnetic poles.

As the magnetoresistive film 21, a spin valve film was used. Cu having a thickness of 1 μm was used for the coil 24. When recording and reproduction were performed with the magnetic head having the above-described structure, it was found that high-frequency recording and reproduction with a maximum recording frequency of 100 MHz or more was possible. This is probably because the magnetic head according to the present invention was used for the magnetic head.

In this embodiment, the upper shield layer 23 is formed by a sputtering method, but may be formed by a plating method. Further, by using a two-layer plating film, a higher effect can be obtained.

Further, in the present embodiment, the lower core of the recording head and the upper shield of the reproducing head are also used, but they can be formed separately.

Embodiment 4 A magnetic disk drive was manufactured using the magnetic head of the present invention described in Embodiment 3. FIG.
1 shows a schematic diagram of the structure of the magnetic disk drive.

For the recording layer of the magnetic recording medium 31, a material made of a Co-Cr-Pt alloy having a residual magnetic flux density of 2500 Oe was used. The track width of the recording head of the magnetic head 33 was 2.5 μm, and the track width of the reproducing head was 2 μm. The magnetic core material of the recording head in the magnetic head 33 is different from that of the conventional recording head using permalloy.
Since it has a high resistance, a high saturation magnetic flux density, and a good magnetic domain structure of the magnetic poles, it is possible to manufacture a magnetic disk device compatible with high frequencies. The magnetic head of the present invention is effective for a magnetic recording / reproducing apparatus having a maximum recording frequency of 100 MHz or more.

[0042]

As described above, the lower magnetic film and one end formed on the lower magnetic film are in contact with one end of the lower magnetic film.
The other end is opposed to the other end of the lower magnetic film via a magnetic gap, and intersects the magnetic core via an upper magnetic film forming a magnetic circuit and an electrically insulated film between the two magnetic films. A thin-film magnetic head comprising a coil having a predetermined number of turns, wherein a two-layer film of a high saturation magnetic flux density magnetic layer / a low magnetostrictive magnetic layer having a changed current density in a thin film magnetic head having an upper magnetic film formed by electroplating. The magnetic domain structure can be optimized without heat treatment, and a magnetic head having a maximum recording frequency of 100 MHz or more can be manufactured.

Further, by using the above-mentioned magnetic head, a high-performance magnetic recording / reproducing apparatus can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a Ni—Fe—S composition and a current density.

FIG. 2 is a graph showing the relationship between magnetostriction constant, electrical resistivity and current density.

FIG. 3 is a graph showing a relationship between a saturation magnetic flux density and a current density.

FIG. 4 is a graph showing the relationship between the magnetostriction constant and the thickness of a high saturation magnetic flux density magnetic layer in a plated two-layer film.

FIG. 5 is a sectional view of a thin-film magnetic head.

FIG. 6 is a graph showing the relationship between overwriting and the thickness of a high saturation magnetic flux density magnetic layer in a thin-film magnetic head using a two-layer plating film of the present invention.

FIG. 7 is a graph showing the relationship between overwrite and recording frequency in a thin-film magnetic head using a two-layer plating film of the present invention.

FIG. 8 is a graph showing the relationship between the composition of the Ni—Fe—Cr plating film and the current density.

FIG. 9 is a graph showing the relationship between magnetostriction constant, electric resistivity, and current density.

FIG. 10 is a graph showing a relationship between a saturation magnetic flux density and a current density.

FIG. 11 is a schematic diagram of a magnetic head using the thin-film magnetic head of the present invention.

FIG. 12 is a schematic diagram of a magnetic disk drive using the thin-film magnetic head of the present invention.

[Explanation of symbols]

11: substrate, 12: lower magnetic film, 13: magnetic gap film, 14, 16: insulating film, 15, 24: coil, 17,
25: Upper magnetic film, 18: Protective film, 21: Magnetoresistance effect film, 22, 23: Shield layer, 26: Base, 27: Electrode, 31: Magnetic recording medium, 32: Magnetic recording medium drive unit,
33: a magnetic head; 34: a magnetic head drive unit; 35: a recording / reproducing signal processing system.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor, Moriaki Fuyama 1-280, Higashi-Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Inside the Central Research Laboratory of the Works (72) Inventor Gen Oikawa 2880 Kozu, Odawara-shi, Kanagawa Storage Systems Division, Hitachi, Ltd.

Claims (9)

[Claims] A lower magnetic film formed on the lower magnetic film, one end of which is in contact with one end of the lower magnetic film, and the other end of which faces the other end of the lower magnetic film via a magnetic gap; In a thin-film magnetic head comprising a coil having a predetermined number of turns intersecting a magnetic core via an upper magnetic film to be formed and a film electrically insulated between the two magnetic films, at least the upper magnetic film or the lower magnetic film One is a thin-film magnetic head composed of two magnetic films mainly composed of an alloy of Ni and Fe formed by changing the current density from the same plating bath,
A thin film magnetic head characterized in that the magnetic layer facing the magnetic gap in the two magnetic films has a high saturation magnetic flux density. 2. The thin-film magnetic head according to claim 1, wherein the thickness of the magnetic layer near the magnetic gap of the two magnetic films is 0.5 μm or more. 3. A thin-film magnetic head using a two-layer magnetic film according to claim 1 or 2, wherein a magnetic layer far from the magnetic gap of the two-layer magnetic film has a negative magnetostriction constant or a magnetic gap having a negative value. A thin-film magnetic head characterized by having a magnetostriction constant lower than that of a magnetic layer facing the thin-film magnetic head. 4. The thin-film magnetic head according to claim 1, wherein said two-layer magnetic film is a composition modulation film of Ni—Fe—S. 5. The thin-film magnetic head according to claim 4, wherein the concentration ranges of the divalent Ni metal ion and the divalent Fe metal ion are 5 to 20 g / l and 1.7 to 20 g, respectively.
/ L, a plating bath containing a solvent in which the ion ratio of Ni to Fe is 1 to 3 and in which thiourea is added as a stress relaxing agent and further a surfactant is added. A thin-film magnetic head characterized in that two magnetic films formed by changing the density are formed on at least one of an upper magnetic film and a lower magnetic film. 6. The thin-film magnetic head according to claim 1, wherein said two-layer magnetic film comprises Ni--Fe
A thin-film magnetic head comprising a composition modulation film of an alloy containing at least one of r, Mo, and W. 7. The thin-film magnetic head according to claim 6, wherein the concentration ranges of the divalent Ni metal ion and the divalent Fe metal ion are 5 to 20 g / l and 0.5 to 2.7 g, respectively.
/ L, a stress relaxing agent, a surfactant, and a metal of Cr, Mo, W having a total amount of 0.7 g / l or less, comprising a solvent having an ion ratio of Ni to Fe of 6 to 8 as described above. A two-layer magnetic film formed by changing a current density by using a plating bath to which at least one of ions is added is formed on at least one of an upper magnetic film and a lower magnetic film. head. 8. A composite magnetic head comprising a combination of the thin-film magnetic head according to claim 1 and a multilayer magnetoresistive element. 9. A magnetic recording / reproducing apparatus equipped with the magnetic head according to claim 8.