JP3143340B2 - Thin film magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductive thin film magnetic head used for a floating magnetic head, for example, and more particularly to a thin film having excellent magnetic properties and in which the upper core layer is hardly peeled off. Related to a magnetic head.

[0002]

2. Description of the Related Art FIG. 3 is a perspective view showing a floating magnetic head H mounted on a hard disk drive as an example of using a thin film magnetic head. Slider 1 of this magnetic head H
(A) is the leading side facing the upstream side in the moving direction of the disk surface, and (b) is the trailing side. On the surface of the slider 1 facing the disk, rail-shaped ABS surfaces 1a, 1a, 1b and an air groove 1c are formed. A thin-film magnetic head 2 is provided on an end face 1d of the slider 1 on the trailing side.

FIG. 4 is an enlarged view of a cross section taken along line IV-IV of FIG. The thin-film magnetic head 2 is a composite magnetic head in which an MR head h1 utilizing a magnetoresistance effect and an inductive head h2 are stacked. The inductive head h2 has a lower core layer 10 and an upper core layer 11. The lower core layer 10 is also used as an upper shield layer of the MR head h1. Tip 11 of upper core layer 11
a and the lower core layer 10 are opposed to each other with a small gap therebetween, and a gap layer 14 made of an insulating material such as Al ₂ O ₃ (alumina) is interposed therebetween to form a magnetic gap G for magnetic recording. ing. On the gap layer 14, an insulating material layer 15 made of an insulating material such as a resist, and a coil layer 13 surrounded by the insulating material layer 15 are formed. The base end 11 b of the upper core layer 11 is magnetically connected to the lower core layer 10 via a contact hole formed in the insulating material layer 15. On the upper part of the upper core layer 11,
A protective layer 16 made of an insulating material such as AL ₂ O ₃ is formed.

FIG. 5 shows a lower core layer 10 and an upper core layer 11.
The shape of the coil layer 13 is shown in a perspective view. The coil layer 13 is formed of a conductive material such as copper (Cu), and is formed in a spiral pattern around the base end 11 b of the upper core layer 11. Although only two coil layers 13 are shown in FIG. 5 for convenience of illustration, in an actual magnetic head, the coil layer 13 is formed in multiple spirals. A recording current is applied to the coil layer 13, a magnetic field is applied to the core layer, and a magnetic field leaking from a magnetic gap G formed by the lower core layer 10 and the upper core layer 11 causes a magnetic field on a recording medium such as a hard disk. The signal is recorded. The lower core layer 10 and the upper core layer 11
Are both formed by plating with permalloy (Fe-Ni alloy).

[0005]

The thin-film magnetic head 2 of this type is obtained by laminating each material layer as described above. However, peeling of any one of the material layers greatly affects the yield of the magnetic head. . This film peeling is likely to occur from the portion exposed on the ABS 1b. In the conventional thin-film magnetic head 2 shown in FIGS. 4 and 5, the film is easily peeled particularly at the upper core layer 11. The reason is, conventionally,
In order to prevent the magnetic characteristics of the inductive head h2 from deteriorating, the lower core layer 10 and the upper core layer 11 are formed so as to have the same iron content as possible. However, in a permalloy thin film layer, the internal stress (internal residual stress) remaining during film formation increases as the iron content increases.

As a result, in the upper core layer 11 located on the surface layer side of the thin-film magnetic head 2, the film is easily peeled off due to the internal stress. That is, the upper core layer 11 on the surface layer has a thin layer such as the protective layer 16 on the surface and has a weak binding force. Therefore, when the internal stress is large, the upper core layer 11 and the gap layer 14 or the insulating material layer 15 are formed. The film is apt to peel off. Further, when the thickness of the upper core layer 11 is larger than the thickness of the lower core layer 10, the distortion to be caused by the internal stress of the upper core layer 11 becomes large, and the film is peeled off in the upper core layer 11. Are more likely to occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended to reduce the internal stress of the upper core layer so as to make it difficult for the upper core layer to peel off the film and to prevent the deterioration of the magnetic characteristics. It is an object of the present invention to provide a thin-film magnetic head according to the present invention.

[0008]

According to the present invention, there is provided a thin film magnetic device comprising a lower core layer and an upper core layer opposed to each other via a magnetic gap, and a coil layer for applying a magnetic field to the core layer.
In the head, the upper core layer and the lower core layer are both
-Formed of malloy (Fe-Ni alloy)
The iron content (% by weight) of the magnetic material in the lower core layer
Less than the iron content (% by weight) of the magnetic material of the
The iron content of the lower core layer is 17.2% by weight.
As described above, the iron content in the upper core layer is 13.9.
Not less than 16.6% by weight and more than 2% by weight, and both cores
The difference between the iron contents in the layers is 1.5% by weight or more.
The content is not more than 7% by weight . In the present invention, the content of iron contained in the lower core layer is:
It is preferably 18.7% by weight or less.

The present invention is more effective when the thickness of the upper core layer is larger than that of the lower core layer.

[0010]

[0011]

[0012]

[0013]

[0014]

According to the present invention, when the lower core layer and the upper core layer are formed of the same kind of magnetic material, for example, permalloy (Fe-Ni alloy), the amount of iron contained in the upper core layer is reduced to the lower core layer. The present invention has been made in view of the fact that even if the amount is smaller than the amount of iron contained within a certain range, deterioration of the electromagnetic conversion characteristic, that is, the overwrite characteristic as the inductive head (writing head) hardly occurs.
In a magnetic material containing iron, such as permalloy, as the amount of iron increases, the internal stress (internal residual stress) during film formation increases, and the film tends to peel off. Further, when the amount of iron contained is reduced, the internal stress is reduced. Thus, as a result of an experiment, it was confirmed that if the difference between the iron contents of the two cores was within a certain range, the magnetic characteristics (overwrite characteristics) of the head hardly deteriorated. Therefore, the amount of iron in the upper core layer which is located on the surface layer side of the thin film magnetic head and in which film peeling is likely to occur is made smaller than the amount of iron in the lower core layer so that film peeling of the upper core layer can be effectively prevented. I made it. Further, when the difference in the amount of iron is within a certain range, the electromagnetic conversion characteristics (overwrite characteristics) of the inductive head (write head) are lower than those of the head in which the lower core layer and the upper core layer have the same amount of iron. ) Are equivalent.

In the present invention, the problem of film peeling is solved by reducing the iron content of the upper core layer located on the surface layer side of the thin-film magnetic head. When the thickness is larger than the thickness of the core layer, more excellent effects are exhibited. In other words, the larger the film thickness, the greater the strain that is caused by internal stress during film formation, and the more easily the film is peeled off. It is possible to effectively prevent the upper core from being easily peeled.

[0016]

Embodiments of the present invention will be described below. As shown in FIG. 3, the thin-film magnetic head 2 of the present invention is provided, for example, on the trailing end face 1d of the slider 1 of the floating magnetic head H. The thin-film magnetic head 2 shown in the embodiment corresponds to FIG.
(Enlarged sectional view taken along the line IV-IV in FIG. 3), which is a composite magnetic head, in which an MR head (read head) h1 and an inductive head (write head) h2 are provided on a trailing side end surface 1d of the slider 1. They are stacked in order.

The MR head (read head) h1 detects a magnetic flux leaking from a recording medium such as a disk using the magnetoresistance effect and reads a magnetic signal. FIG.
As shown in FIG. 4 (enlarged view taken in the direction of arrow VI), the MR head (read head) h1 includes a sendust (Fe—Al—Si) formed on the trailing side end surface 1d of the slider 1.
Alumina (Al ₂ ) on the lower shield layer 21 of
A lower gap layer 22 made of a non-magnetic material such as O ₃ ) is provided. A magnetoresistive element (MR element) 23 is stacked on the lower gap layer 22. This MR element 23 has a three-layer structure, and a SAL film 23a
(Co-Zr-Mo alloy), SHUNT of non-magnetic material
The film 23b (for example, Ta (tantalum)) is an MR film 23c (Fe—Ni alloy) having a magnetoresistance effect. MR
On both sides of the element 23, a hard bias layer 24 (Co-Cr-Ta alloy) for applying a bias magnetic field to the MR film 23c.
And an electrode layer 25 (W) for applying a detection current to the MR film 23c.
(Tungsten) or Cu (copper)). Further, an upper gap layer 26 made of alumina or the like is formed thereon. In this embodiment, the upper shield layer is formed on the upper surface of the upper gap layer 26 of the MR head (read head) h1, and this upper shield layer is formed on the lower core layer of the inductive head (write head) h2. Also used as 10.

As described in the prior art, the inductive head (write head) h2 has a pattern in which a gap layer 14 is formed on the lower core layer 10 and is spirally planarly formed thereon. The formed coil layer 13 is formed. The coil layer 13 includes the insulating material layer 1
It is surrounded by five. The upper core layer 11 formed on the insulating material layer 15 has a front end 11a opposed to the lower core layer 10 at a small gap on the ABS 1b, and a base end 11b is magnetically opposed to the lower core layer 10. It is connected to the. A protective layer 16 made of alumina or the like is provided on the upper core layer 11. In the inductive head (write head) h2, a recording current is applied to the coil layer 13 and the coil layer 13
, A recording magnetic field is applied to the core layer. Then, a magnetic signal is recorded on a recording medium such as a hard disk by a leakage magnetic field from the lower core layer 10 at the portion of the magnetic gap G and the tip 11a of the upper core layer 11.

Here, the lower core layer 10 and the upper core layer 11
Are formed of the same kind of magnetic material, that is, a magnetic material containing the same metal atom. In the embodiment, both the lower core layer 10 and the upper core layer 11 are made of permalloy (Fe-N
(i-based alloy). However, the amount of iron contained in the upper core layer 11 located on the surface layer side of the thin-film magnetic head 2 is smaller than the amount of iron contained in the lower core layer 10 in a certain range. By reducing the amount of iron in the upper core layer 11, the internal stress (internal residual stress) remaining in the permalloy layer at the time of film formation by plating.
, Thereby making it difficult for the upper core layer 11 to peel off.

FIG. 2 shows the result of measuring the relationship between the iron content of the permalloy layer and the internal stress (internal residual stress). The sample used for this measurement was a permalloy film having a thickness of 3.0 μm formed on a glass substrate. However, a plurality of types in which the amount of iron in the film was changed by changing the plating conditions were prepared, and the internal stress was measured for each of the plurality of types of permalloy films. In FIG. 2, the abscissa indicates the amount of iron in the film in% by weight. The vertical axis indicates the stress (residual stress) in the film (× 10 ⁸ dyn).
/ Cm ² ). On the vertical axis, plus is the tensile stress and minus is the compressive stress. From FIG. 2, it can be seen that the permalloy film is in a state in which the larger the amount of iron, the greater the internal stress during film formation and the more easily the film is peeled off.

Next, Tables 1 and 2 and FIG. 1 show the case where the amount of iron contained in the upper core layer 11 is smaller than the amount of iron contained in the lower core layer 10 in the inductive type thin film magnetic head. 5 shows the results of measuring the electromagnetic conversion characteristics of the head. In this experiment, 16 kinds of samples indicated by A to P in Table 1 were used as examples. In each of the samples of the embodiment, a thin film magnetic head 2 which is a composite magnetic head is formed on a trailing end face 1d of a slider 1 having a shape shown in FIG. Is as shown in FIG.

The average value of the thickness of the lower core layer 10 formed by plating in each of the samples A to P was 2.8 μm, and the average value of the thickness of the upper core layer 11 was 3.2 μm. Each sample A
To the lower core layer 10 and the upper core layer 11 of each of the magnetic heads
Are formed by plating permalloy (Fe-Ni-based alloy). In each sample, the iron content in the permalloy layers of the upper core layer 11 and the lower core layer 10 was measured. The measuring method is EPMA (Electron Prog Micro Analyzer) analysis. Or X
Similar measurement is possible by MA (X-ray / micro analyzer) analysis. In each sample, the lower core layer 1
0 and the iron content of the upper core layer 11 were measured twice, and Table 1 shows the average value.

Table 1 shows the amount of iron contained in the upper core layer 11 and the amount of iron contained in the lower core layer 10 by weight%. In Table 1, the difference between the amount (% by weight) of iron contained in the lower core layer 10 and the amount (% by weight) of iron contained in the upper core layer 11 is indicated by% by weight. In each of the samples shown in Table 1, the amount of iron contained in the upper core layer 11 was 1.58% by weight to 3.6% more than the amount of iron contained in the lower core layer 10.
It is reduced in the range of 7% by weight. Samples A to
Magnetic signals were recorded on the hard disk using the P thin film magnetic heads 2. The overwrite characteristics at this time are as follows:
Each sample is shown in the rightmost column of Table 1. The overwrite characteristic indicates the reproduction level of the original residual magnetic signal when the magnetic signal is overwritten on the hard disk by a minus dB value.

Table 2 shows the same measured values as in Table 1 for Comparative Samples (1) and (2). This comparative sample relates to a magnetic head having the same structure as the samples A to P shown in Table 1, but in each of the comparative samples (1) and (2), the lower core layer 1
0 and the upper core layer 11 had almost the same amount of iron contained. As shown in Table 2, the difference in iron content between the two layers is 0.1% by weight or 0.05% by weight. Also in Comparative Examples (1) and (2), the overwrite characteristics are shown in the rightmost column of Table 2.

[0025]

[Table 1]

[0026]

[Table 2]

Further, in FIG. 1, samples A to
P, and comparative samples (1) and (2) shown in Table 2,
The amount of iron in the upper core layer 11 and the lower core layer 10 is shown in a graph. In FIG. 1, the symbol “○” indicates the amount (% by weight) of iron in the lower core layer 10, and the symbol “□” indicates the amount (% by weight) of iron in the upper core layer 11. is there. Table 1
In each of the samples A to P, the difference between the amount of iron contained in the lower core layer 10 and the amount of iron contained in the upper core layer 11 is 3.67% by weight at the maximum (3 digits at one decimal place). 0.78% by weight) and a minimum of 1.58% by weight (one digit to one decimal place).
5% by weight). On the other hand, in Table 2, each comparative sample (1)
In (2), the difference between the amount of iron contained in the lower core layer 10 and the amount of iron contained in the upper core layer 11 is 0.05% by weight or 0.1% by weight.

From Tables 1 and 2, it can be seen that the samples A to P in which the amount of iron differs between the lower core layer 10 and the upper core layer 11 within a certain range, and that Comparing the overwrite characteristics of the comparative samples (1) and (2) having almost the same amount, there is almost no difference in the overwrite characteristics between each of the samples A to P and the comparative samples (1) and (2). I understand. In a hard disk drive, the overwrite characteristic is almost -30.
If it is (dB) or less or -40 (dB) or less, there is no practical problem in reproducing digital signals. Therefore, it is understood that the samples A to P have almost no practical problems. Moreover, according to FIG. 2, it can be seen that when the amount of iron in the permalloy film decreases, the internal stress during film formation decreases, and film peeling is less likely to occur. In FIG. 2, the amount of iron is 1.
It is understood that when the content is reduced in the range of 5% by weight to 3.7% by weight, the internal stress is significantly reduced.

Therefore, by reducing the amount of iron in the upper core layer 11 located in a portion close to the surface layer of the thin-film magnetic head 2 within the above range, peeling of the upper core layer 11 is less likely to occur than in the conventional case. In the case where the thickness of the upper core layer 11 is larger than that of the lower core layer 10, film peeling has conventionally been easily caused. In this case, too, the film peeling can be prevented by reducing the amount of iron in the upper core layer 11. Less likely to occur. That is, in the thin film head in which the thickness of the upper core layer 11 is larger than that of the lower core layer 10, the upper core layer 11 having a larger thickness on the surface layer is more easily peeled off. By reducing the amount of iron, film peeling can be effectively prevented. From the above results, when the lower core layer 10 and the upper core layer 11 are formed of the same type of magnetic material containing iron, for example, permalloy, the upper core layer 11 with respect to the amount of iron contained in the lower core layer 10 The difference in the amount of iron contained is up to 3.67
% By weight (3.7% by weight) and a minimum of 1.58% by weight (about 1.5% by weight). By setting this range, the magnetic characteristics of the magnetic head hardly deteriorate.

Further, from the results shown in Tables 1 and 2 and FIG. 1, in the case where the upper core layer 11 and the lower core layer 10 are formed of permalloy, the amount of iron contained in the lower core layer 10 is reduced by 17%. 0.21% by weight (17.2% by weight) or more and 18.66% by weight (18.7% by weight) or less, and the amount of iron contained in the upper core layer 11 is 13.93% by weight.
(About 13.9% by weight) or more and 16.56% by weight (about 1%).
6.6% by weight) or less.
By setting the amount of iron contained in both layers 10 and 11 within this range, the electromagnetic conversion characteristics as an inductive head (write head) can be made almost equal to those of Comparative Examples (1) and (2), and the upper core The layer 11 is less likely to peel off.

In the embodiment shown in the drawings, a composite magnetic head in which an MR head (read head) h1 and an inductive head (write head) h2 are stacked is described. However, the present invention relates to an MR head (read head). )
h1 and without the lower core layer 10 and the upper core layer 1
The present invention is also applicable to a configuration in which only the inductive head formed by the coil 1 and the coil layer 13 is mounted on the slider 1 or the like.

[0032]

As described above, according to the present invention, in the inductive type thin film magnetic head, when the upper core layer and the lower core layer are formed of permalloy,
The iron content of the upper core layer located on the surface layer is
Iron content of each core layer
Range of the iron content of the two core layers
To prevent film peeling of the upper core layer
At the same time, it is possible to obtain magnetic properties equivalent to those of the related art .

Further, by making the difference between the amount of iron contained in the lower core layer and the amount of iron contained in the upper core layer within a certain range, the magnetic head in which the amounts of iron in both layers are substantially the same. And equivalent magnetic characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 shows samples A to A of a thin-film magnetic head according to an embodiment of the present invention.
P is a diagram showing the amounts of iron in the lower core layer and the upper core layer in Comparative Examples (1) and (2),

FIG. 2 is a diagram showing the relationship between the amount of iron in the permalloy film and internal stress,

FIG. 3 is a perspective view of a slider on which the thin-film magnetic head is mounted.

FIG. 4 shows the structure of the composite type thin-film magnetic head in FIG.
An enlarged sectional view of the line V-IV,

FIG. 5 is a half sectional perspective view showing the shapes of a lower core layer and an upper core layer in the composite thin film magnetic head;

FIG. 6 is an enlarged view of the MR head in FIG.

[Explanation of symbols]

 H Flying magnetic head 1 Slider 1a, 1b ABS surface 1d End surface on trailing side h1 MR head h2 Inductive head 10 Lower core layer 11 Upper core layer 13 Coil layer 14 Gap layer 15 Insulating material layer 16 Protective layer

Claims (3)

(57) [Claims] 1. A thin-film magnetic head comprising a lower core layer and an upper core layer opposed to each other via a magnetic gap, and a coil layer for applying a magnetic field to the core layer. Permalloy (Fe-
Ni-based alloy) and the magnetic material of the upper core layer
The iron content (% by weight) of the magnetic material of the lower core layer
Less than the iron content (% by weight), the lower core layer
Iron content is more than 17.2% by weight, upper core
The iron content in the layer is 13.9% by weight or more and 1% by weight.
Not more than 6.6% by weight and contained in both core layers
The difference in the content is 1.5% by weight or more and 3.7% by weight or less.
Thin-film magnetic head, characterized in that. 2. The iron content of the lower core layer
2. The thin-film magnetic layer according to claim 1, wherein is less than 18.7% by weight.
head. 3. The thin-film magnetic head according to claim 1, wherein the thickness of the upper core layer is larger than the thickness of the lower core layer.