JPH02312006A - Thin-film magnetic head - Google Patents

Abstract

PURPOSE:To obtain the head having a large head performance index by setting the direction of the axis of easy magnetization of upper and lower magnetic cores as the normal direction of a gap surface in a gap part and in parallel with the contact surface in a back contact part. CONSTITUTION:The direction of the axis of easy magnetization of the upper magnetic core 1 and the lower magnetic core 1 ' is aligned to the normal direc tion of the surface of the gap 2 in a gap forming part. This direction is so set as to be approximately parallel with the back contact surface in the back contact part. The flow direction of the magnetic fluxes from a medium intersects orthogonally with the direction of the axis of easy magnetization and the large reproduced output is obtd. The flow of the magnetic fluxes in the magnetic gap forming part is in the direction of the axis of easy magnetiza tion at the time of inductance measurement. The magnetic permeability is then lowered and the inductance L is diminished. The large reproduced output S is obtd. in this way and the head having the large performance index S/L<1/2> is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head suitable for use in video tape recorders and the like.

[Prior art] Conventionally, thin-film magnetic heads have been developed using materials from the Applied Magnetics Research Group (
March 11, 1985) Document number: MSJ39-5
It is reported in the paper entitled "Thin Film Magnetic Head for Hard Disk Devices" by Shinji Narishige et al., pp. 41-49, but in these conventional thin film magnetic heads, uniaxial anisotropy is imparted to the magnetic core. The axis of easy magnetization is set parallel to the surface of the magnetic core and parallel to the sliding surface of the medium. Such a thin film magnetic head.

This will be explained below with reference to FIG. 6(a). However, in the figure, 1 is the upper magnetic core and 1' is the lower magnetic core.

2 is a magnetic gap, and 3 is a thin film coil.

A lower magnetic core 1' is provided on a substrate (not shown).

Furthermore, an upper magnetic core 1 is provided thereon with a nonmagnetic insulating layer interposed therebetween. At the left ends of the lower magnetic core 1' and the upper magnetic core 1 in the drawing, these magnetic cores face each other closely with an extremely thin non-magnetic insulating layer interposed therebetween, forming a magnetic gap 2. The end surfaces of the lower magnetic core 1' and the upper magnetic core 1, where the magnetic gap 2 is formed, form a medium sliding surface.

Although not shown, on the side opposite to the medium sliding surface (on the right side of the drawing), a back contact part is formed where the upper magnetic core 1 and the lower magnetic core 1' are connected.
The upper magnetic core 1 and the lower magnetic core 1' constitute a loop-shaped magnetic path. The thin film coil 3 is wound around this back contact portion, and a portion thereof passes between the upper magnetic core 1 and the lower magnetic core 1'.

In the thin film magnetic head having such a configuration, the upper magnetic core 1
and the lower magnetic core 1', the axis of easy magnetization is set in the direction shown by ■, which is parallel to the surface of these magnetic cores and parallel to the sliding surface of the medium, and the direction of the easy magnetization axis is set in the direction shown by ■, which is parallel to the surface of these magnetic cores and parallel to the sliding surface of the medium. The magnetic flux flowing into the magnetic core flows as indicated by the dashed arrow. Therefore, the direction of propagation of magnetic flux and the direction of the axis of easy magnetization are perpendicular to each other at any location in the magnetic core. Generally, the magnetic permeability of a magnetic material having -axis anisotropy is maximum in the direction perpendicular to the axis of easy magnetization. Therefore, in this thin-film magnetic head, the magnetic permeability of the magnetic core during reproduction is at its maximum, and as a result, the magnetic resistance is sufficiently reduced and a large reproduction output can be obtained.

[Problem to be solved by the invention] As described above, a conventional thin film magnetic head with uniaxial anisotropy so that the magnetic flux flows orthogonally to the axis of easy magnetization can obtain a large reproduction output. However, on the other hand, because of the -axis anisotropy, the inductance of the head also increases, and if the playback output is S and the inductance of the head is L, the performance of the head is expressed as F, /l. There was a problem that the index became small. This will be explained below using FIG. 6(b).

In the same figure (b), the flow of magnetic flux during inductance measurement is in the direction shown by the broken line arrow. In this inductance measurement as well, the direction of propagation of magnetic flux is perpendicular to the axis of easy magnetization, and the magnetic permeability is maximized. Since the inductance of the head is proportional to the magnetic permeability, this thin film magnetic head also has a large inductance.

As mentioned above, in the conventional thin film magnetic head, the reproduction output S
Since the inductance L and the inductance L both become large, the performance index of the head S/v'T: is small.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a thin film magnetic head with a large reproduction output and a high head performance index.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a uniaxial anisotropy in which the axis of easy magnetization of the magnetic gap forming portions of the upper and lower magnetic cores is the normal direction of the surface of the magnetic gap. Give direction.

[Function] During playback, as described above, the upper and lower parts of the magnetic gap forming part
Even if the direction of the easy axis of magnetization of the lower magnetic core is set, the flow direction of the magnetic flux from the medium is perpendicular to the direction of the easy axis of magnetization, and the easy axis of magnetization does not reduce the reproduction output.

Therefore, a large playback output can be obtained.

Further, when measuring inductance, the flow of magnetic flux in the magnetic gear forming portion is in the direction of the axis of easy magnetization, resulting in a decrease in magnetic permeability and a decrease in inductance.

As a result of the above, a large reproduction output can be obtained, and the head performance index is also increased.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a thin film magnetic head according to the present invention, in which 1 is an upper magnetic core, 1' is a lower magnetic core, 2 is a magnetic gap, 3 is a thin film coil, and 4 is a nonmagnetic substrate. , 5 is a medium sliding surface, 6 is a back contact portion, and 7 is a nonmagnetic insulating layer.

In the figure, a lower magnetic core 1' is embedded in a groove provided in a non-magnetic substrate 4, and only a portion where a magnetic gap 2 is formed protrudes from the surface of the non-magnetic substrate 4. The upper magnetic core 1 faces the lower magnetic core 1' to a predetermined depth from the medium sliding surface 5 on the lower magnetic core 1' through a very thin non-magnetic material (not shown), and this part constitutes the magnetic gap 2. A non-magnetic insulating layer (not shown) is provided between the upper magnetic core 1 and the lower magnetic core 1' in the deeper part than the magnetic gap 2, and furthermore, in the deeper part, the upper magnetic core 1 and the lower magnetic core 1' A back contact portion 6 is formed by coupling with the lower magnetic core 1'. An upper magnetic core 1.A thin film coil 3 is wound around this back contact portion 6, and a portion of the thin film coil 3 is isolated by a nonmagnetic insulating layer. It passes between the lower magnetic cores 1'.

The magnetic cores 1 and 1' are made of CoNbZ except for the magnetic gap forming part and the back contact part 6 of the upper magnetic core 1.
It is composed of a laminated body of an r film and a nonmagnetic insulating layer 7, and the magnetic gap forming portion of the upper magnetic core 1 and the back contact portion 6 are composed only of a CoNbZr film. This is because magnetic flux flows in the thickness direction of the magnetic core in the magnetic gap forming part and the back contact part 6, so if these two parts are made into a laminated structure, the magnetic flux crosses the nonmagnetic insulating layer and the magnetic resistance of the core increases. This is to prevent it from increasing. Further, the lower magnetic core 1' is formed in a groove with an inclined side wall on the non-magnetic substrate 4 using a thin film forming method. As a result, even if the lower magnetic core 1' has the above-described laminated structure, all of its magnetic layers are exposed at the joint surface with the upper magnetic core 1, and even in the magnetic gap forming part and the back contact part 6.
Magnetic flux does not cross the nonmagnetic insulating layer 7.

In the magnetic gap forming portions of the upper magnetic core 1 and the lower magnetic core 1', the direction of the easy axis of magnetization coincides with the normal direction (perpendicular direction) to the surface of the magnetic gap 2.

In other parts, the direction of the axis of easy magnetization is parallel to the track width direction.

FIG. 2 shows the direction of the axis of easy magnetization and the flow of magnetic flux in the magnetic gap forming part and its vicinity in this embodiment,
FIG. 5(a) shows the time of reproduction, and FIG. 1(b) shows the time of inductance measurement.

In FIG. 2(a), as mentioned above, in the magnetic gap forming part, the axis of easy magnetization in the upper magnetic core 1 and the lower magnetic core 1' is in the plane of the magnetic gap 2, as shown by the mark in ). In other parts, it is parallel to the track width direction, as shown by the mark θ.

During reproduction, the propagation direction of the magnetic flux is perpendicular to the direction of the axis of easy magnetization in both the upper magnetic core 1 and the lower magnetic core 1', as shown by the broken line arrow. Therefore, the magnetic resistance during reproduction is as small as that of a conventional thin-film magnetic head.
Large playback output can be obtained. When measuring inductance, the propagation direction of magnetic flux coincides with the direction of the axis of easy magnetization only in the magnetic gap forming part, and is perpendicular to the direction of easy magnetization in other parts, as shown by the broken line arrow in Figure 2 (b). . in general,
The magnetic permeability in the easy-magnetization axis direction is based on domain wall movement, and for this reason, as the signal frequency increases, the domain wall movement cannot sufficiently follow changes in the magnetic field, and the anomalous eddy current effect increases. Magnetic permeability decreases. Therefore, in this embodiment, the inductance is smaller than that of a conventional thin film magnetic head.

As described above, by making the axis of easy magnetization in the magnetic gap forming part of the magnetic core coincide with the normal direction of the surface of the magnetic gap 2, and by making the axis of easy magnetization in other parts coincide with the track width direction. , the inductance can be reduced without impairing the reproduction output. Therefore, S/
V7″L, that is, the performance index of the head increases.

Next, a method for realizing the above-mentioned magnetic anisotropy in this embodiment will be explained.

In this embodiment, different methods are used for the upper magnetic core 1 and the lower magnetic core 1', as shown below.

As an example, assume that the width of the upper magnetic core 1 in the track width direction is 40 μm at the magnetic gap forming portion and 200 μm around the back tact portion 6.

Further, the thickness of the film is a single layer of 20 μm in the magnetic gap forming portion and the back contact portion 6, and a double layer of 10 μm in other portions (the back contact portion 6 is formed in the lower magnetic core 1').
Therefore, the demagnetizing field coefficient in the film thickness direction of each part of the upper magnetic core 1 is the demagnetizing field coefficient of the magnetic gap forming part <the demagnetizing field coefficient of the back contact part 6, etc. This is the demagnetizing field coefficient of the part.

When magnetic materials having different demagnetizing field coefficients are subjected to heat treatment in a magnetic field under the same conditions, the obtained magnetic anisotropy is different. In this embodiment, the above magnetic anisotropy is imparted to the upper magnetic core 1 by utilizing such properties of the magnetic material.

That is, uniaxial anisotropy with a large anisotropy constant with the track width direction as the axis of easy magnetization is imparted to the entire upper magnetic core 1 in advance, and then the demagnetizing field is larger than the demagnetizing field of the magnetic gap forming part and the back contact is applied. The magnetic field heat treatment is performed by applying an external magnetic field smaller than the demagnetizing field of the magnetic gap 2 in the normal direction of the surface of the magnetic gap 2. As a result, in the magnetic gap forming part, the magnetic gap is Uniaxial anisotropy is imparted with the normal direction of the two surfaces as the axis of easy magnetization. In other parts, the initial magnetic anisotropy, which is uniaxial anisotropy with the track width direction as the axis of easy magnetization, is maintained as it is. However, the above demagnetizing field is a demagnetizing field at the heat treatment temperature. In this way, by forming a part of the upper magnetic core 1 into multiple layers, it is possible to impart different magnetic anisotropy to one part.

The entire lower magnetic core 1', including the magnetic gap forming part, is multilayered, and the lower magnetic core 1', which has a large demagnetizing field in the direction normal to the surface of the magnetic gap 2, is provided on a non-magnetic substrate 4. It is embedded in the groove. The cross-sectional shape of the magnetic gap forming portion of this groove is approximately V-shaped, and the slope angle φ of the V-shaped groove with respect to the surface of the non-magnetic substrate 4 is 30” or more, preferably 45° to 80°. 273 or more of the cross-sectional area of the lower magnetic core 1' at the magnetic gap forming portion is set to be the cross-sectional area of the portion directly above this slope.

When a CoNbZr film is formed in this groove, a columnar structure extending approximately perpendicular to the surface of the magnetic gap 2 is generated due to the oblique incidence angle effect on the sloped portion, and by applying heat treatment to this columnar structure, perpendicular magnetic anisotropy can be obtained. It will be done.

Regarding the peripheral portion of the back contact portion 6 of the lower magnetic core 1', since the core width is wide and the bottom surface is formed in a groove with a flat surface, no perpendicular magnetic anisotropy occurs as in the magnetic gap forming portion. Therefore, an axis of easy magnetization can be provided in the track width direction in the same manner as in the upper magnetic core 1.

FIG. 3 is a side view showing an example of the magnetic domain structure in this embodiment. As shown in the figure, in the magnetic gap forming part there is a linear domain wall 9 in the film thickness direction, and in other parts there are zigzag domain walls 9' in the film thickness direction. It was measured. These are all magnetic domain structures of -axis anisotropic films, and are respectively in the film thickness direction and
This is the magnetic domain structure observed when the axis of easy magnetization is in the track width direction.

Next, a method for manufacturing the thin film magnetic head shown in FIG. 1 will be described with reference to FIG. 4, specifically showing an example of materials, film thicknesses, etc. of each part.゛First, on the non-magnetic substrate 4, by photolithographic method and ion etching method, a groove in which the magnetic gap forming part has a V-shape as shown in FIG. , a CoNbZr film and a film 7 of Sin, which is an insulating material between the eyebrows, are formed by sputtering alternately,
By polishing, the parts of the film that are attached to areas other than the grooves are removed.
Then, the magnetic gap forming part and the back contact part 6
A convex portion is formed in a portion corresponding to the convex portion, and a SiO□ film 8, which is a layer of the coil 19, is formed by sputtering so as to fill the concave portion between these convex portions, and the surface is flattened by polishing to form the lower magnetic core 1'. is formed. At this time, the thickness of the CoNbZr film of the lower magnetic core 1' is 10 μm in the first layer, 20 μm in the convex portion of the second layer, and 10 μm in other portions.
The thickness of the film was 0.1 μm (Fig. 4(a)).

Next, a Cu film with a thickness of 3 μm is formed on the coil insulating layer 8 using the magnetron sputtering method, and a thin film coil 3 is formed using the photolithographic method (FIG. 4(b)).
).

Then, a Sin film is formed on the coil insulating layer 8 so that the thin film coil 3 is buried therein, and the surface thereof is flattened by polishing. i Remove the O2 film to form the coil insulating part 8, and further reduce the film thickness to 0 to form the magnetic gap 2.
．． A 3 .mu.m thick Si.sub.2 film 2 is formed by sputtering (FIG. 4(e)).

Next, Sin at a position corresponding to the back contact part 6,
After removing the film to form a through hole, a CoNbZr film with a thickness of 10 μm is formed as the first layer magnetic film of the upper magnetic core 1.
A film is formed thereon, and an interlayer insulating layer 7 with a film thickness of 0.1/
A SiO□ film of Am is sequentially formed (FIG. 4(d)), and after removing the interlayer insulating layer 7 directly above the magnetic gap forming part and the back contact part 6 (FIG. 4(8)), the upper CoNb with a thickness of 10 μm as the second layer of the magnetic core 1
After forming a Zr film, CoNbZ was formed by ion milling.
The upper magnetic core 1 is obtained by processing the r film into a desired shape (FIG. 4(f)).

The wafer process is completed with the above steps. All thin film processing during wafer processing uses photolithographic methods and ion milling methods.

Further, the CoNbZr film is formed using a DC facing sputtering method, and the direction of the plasma convergence magnetic field during film formation is made to coincide with the track width direction. Furthermore, magnetron sputtering is used to create the 5in2 film.

After the wafer process is completed, heat treatment is performed in a magnetic field for 30 minutes at a temperature of 460°C, a magnetic field application direction normal to the surface of the magnetic gap 2, and a magnetic field strength of 1.8 x 10'^/@. Note that this heat treatment temperature of 460°C is the same as the Curie temperature of 420°C on the medium sliding surface side (front part) of the lower magnetic core 1' formed in the groove of the non-magnetic substrate 4, and the Curie temperature of 420°C on the rear part. The temperature was set between 480°C.

After the above-described heat treatment in a magnetic field, a thin film magnetic head is completed through chip processing and head assembly steps.

FIG. 5 shows the head reproduction output per inductance of the thin film magnetic head according to the above embodiment and the conventional thin film magnetic head. As is clear from the figure, the thin film magnetic head according to the above example showed an improvement of 3 to 4 dB compared to the conventional thin film magnetic head.

[Effects of the Invention] As described above, according to the present invention, it is possible to reduce the inductance while increasing the reproduction output to the same level as the conventional technology, and the figure of merit is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the thin film magnetic head according to the present invention, FIG. 2 is an explanatory diagram showing the axis of easy magnetization and the flow of magnetic flux near the magnetic gap of the thin film magnetic head shown in FIG. 3 is a side sectional view showing a specific example of the magnetic domain structure of the thin film magnetic head shown in FIG. 1; FIG. 4 is a process flow chart showing a specific example of the manufacturing process of the thin film magnetic head shown in FIG. 1; Fig. 5 is a graph showing the reproduction output-frequency characteristics of the thin film magnetic head shown in Fig. 1 and the conventional thin film magnetic head, and Fig. 6 shows the axis of easy magnetization and magnetic flux near the magnetic gap of the conventional thin film magnetic head. It is an explanatory diagram showing a flow. 1... Upper magnetic core, 1'... Lower magnetic core, 2... Magnetic gap, 3...
Thin film coil, 4...Nonmagnetic substrate, 5...
・Medium sliding surface, 6... Back contact part, 7
......Interlayer insulation layer, 8......Coil absolute first
Figure' \5 Figure 2 Figure 3 Figure 4 Figure 5 Frequency (MHz)

Claims (1)

[Claims] First, first, and second magnetic cores are close to each other in the vicinity of the medium sliding surface to form a magnetic gap, and are coupled to each other at the back with respect to the medium sliding surface side. forming a contact part,
The first and second magnetic cores are isolated between the magnetic gap and the back contact portion, and a portion of the first and second magnetic cores is separated from the back contact portion.
In a thin film magnetic head in which a thin film coil is wound around the back contact portion so as to pass between the magnetic cores, an axis of easy magnetization is formed in at least the portion forming the magnetic gap of the first and second magnetic cores. A thin film magnetic head characterized in that the direction of the magnetic gap corresponds to the normal direction of the plane of the magnetic gap. 2. In claim 1, the direction of the axis of easy magnetization in the portion between the magnetic gap forming portion and the back contact portion in the first and second magnetic cores is parallel to the track width direction. Features a thin film magnetic head. 3. In claim 1 or 2, a portion of the first and second magnetic cores between the magnetic gap forming portion and the back contact portion has a laminated structure of a magnetic film and a nonmagnetic insulation film. A thin film magnetic head featuring: 4. The thin film magnetic head according to claim 1, 2 or 3, wherein the magnetic gap forming portions of the first and second magnetic cores are made of a Co-based alloy layer. 5. The thin film magnetic head according to claim 1, wherein the magnetic gap is formed by providing a nonmagnetic insulating film between the first and second magnetic cores. 6. In claim 1, 2, 3, 4 or 5, the first
, a thin film magnetic head characterized in that one of the second magnetic cores is embedded in a substrate.