JPH11328632A - Magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a record blurring at a recording head by making sizes of an upper and a lower parts of a shared magnetic layer agree with breadths necessary for a shield layer and a magnetic pole respectively. SOLUTION: When an upper and a lower parts of a shared magnetic layer have different specific magnetic permeabilities and saturation magnetic flux densities, with a recording magnetic pole being layered on a magnetoresistance effect type reproduction head, the reproduction head has a magnetoresistance effect element 4 of a thin film of Permalloy via an insulating layer between magnetic shield layers 2 and 6 serving also as magnetic poles. A lower magnetic pole 19 of a recording head is formed on the upper magnetic shield layer 6. At this time, the magnetic shield is formed of Permalloy of a film thickness of 0.7 μm and the magnetic pole 19 is formed of CoTaZr of a saturation magnetic flux density of 1.3T. Thereafter, a coil is formed via an insulating layer 8, onto which an upper magnetic pole 7 is formed. The lower magnetic shield layer 2, upper magnetic shield layer 6, lower magnetic pole 19 and upper magnetic pole 7 have sizes in a breadthwise direction of tracks of 100 μm, 90 μm, 8 μm and 6 μm respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to magnetic recording
The present invention relates to a recording / reproducing separation type composite head suitable for high density recording.

[0002]

2. Description of the Related Art In order to increase the density of magnetic recording, studies are being made on a recording / reproducing separation type magnetic head in which a recording head and a reproducing head are separated and each of them is optimized for higher performance. . As one of the heads, a structure in which an inductive type is used as a recording head and a magnetoresistive effect type is used as a reproducing head, and both are combined is known. In such a head, a structure is known in which one or both of the magnetic layers used as the magnetic shield layer also serve as the magnetic pole of the induction type head. An example of such a structure is disclosed in JP-B-59-3508.
There are a number of known examples, including No. 8.

[0003]

When the magnetic shield layer also functions as the magnetic pole of the recording head, its dimension in the track width direction becomes a problem. Generally, a magnetoresistive effect element needs to be longer than the track width in order to provide anisotropy in the track width direction. In this case, in order to suppress noise generated in a portion other than the track width, the magnetic shield layer needs to cover the entire magnetoresistive element. On the other hand, the dimensions of the recording magnetic pole need to match the track width. As described above, the conventional head cannot satisfy both of the dimensions of the magnetic layer in the track width direction. For this reason, in the case of the separation type head in which the recording head is stacked on the magnetoresistive effect element,
As a compromise, there is known a structure in which the upper magnetic pole is made equal to the track width and the lower magnetic pole is long enough to cover the entire magnetoresistive element. However, in this case, as the recording magnetic pole, the upper magnetic pole and the lower magnetic pole do not have the same track width, so that recording bleeding is likely to occur at the magnetic pole end, and it has been difficult to obtain good recording characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic layer serving both as a magnetic shield layer and a recording magnetic pole layer, and to provide a head structure capable of satisfying both characteristics.

[0005]

The problem is that the dimensions of the lower portion and the upper portion of the magnetic layer, which is also used as the magnetic layer, match the widths required for the shield layer and the magnetic pole, respectively. That is, the problem can be solved by providing a taper or a step in the cross section of the magnetic layer and changing the dimensions of the upper and lower portions of the magnetic layer.

With the above structure, the width of the magnetic layer of the key facing one recording magnetic pole can be made equal to the track width, so that the magnetic flux at the time of writing concentrates on the track width portion. For this reason, it is possible to reduce recording blur of the recording head. On the other hand, the width of the magnetic pole on the side facing the magnetoresistive element can be increased to sufficiently cover the element. Therefore, it is possible to reduce noise of the magnetoresistive effect element caused by the signal magnetic flux from the adjacent track.

[0007]

Embodiment 1 An embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 1 is a plan view of a magnetic head according to the present invention, and FIG. A lower magnetic shield layer 2 is laminated on a head base 1, and a magnetoresistive element 4 is laminated thereon with an insulating layer 3 interposed therebetween. Subsequently, the upper magnetic shield layer 6 is laminated via the insulating layer 5. At this time, the lower dimension is made equal to that of the lower magnetic shield layer 2, and the upper dimension is worked so as to be equal to the dimension of the upper magnetic pole 7.
Further, a conductor layer 9 serving as a coil is laminated thereon with an insulating layer 8 interposed therebetween, and the upper magnetic pole 7 is further laminated via an insulating layer 10. In the magnetic head having such a structure, the shield layers 2 and 6 and the pole layer 7 have permalloy (composition 82Ni-18F) formed by a sputtering method.
e), and the film thickness was 2.0 μm in each case. The dimension at the surface facing the medium is 100 for the lower shield layer 2.
μm, the lower part of the upper shield layer 6 also serving as the lower magnetic pole is 90 μm.
μm, the upper part is 10 μm, and the upper magnetic pole 7 is 8 μm. The step 16 in the lower magnetic pole 6 having two steps is 0.7.
μm. In addition, in order to provide a margin for alignment of the respective layers when laminating, the dimensions of the respective layers are made smaller as going upward. Alumina was used for all of the insulating layers 3, 5, 8, and 10. The thickness of each of the insulating layers 3, 5, 8, and 10 in the portion sandwiched between the magnetic poles is 0.3 μm and 0.4, respectively.
μm, 0.7 μm, and 0.7 μm. The planarization of these insulating layers was performed by using a commonly used etch back method. The conductor layer 9 was made of copper having a thickness of 2.0 μm to form a one-turn coil. A 40-nm-thick permalloy (composition 82) formed by vacuum evaporation
Ni-18Fe), the shape of which has a length in the track width direction of 50 μm and a height of 10 μm. Electrode layers 11 are provided at both ends of this element, and Ti (film thickness: 50
nm) / Au (150 nm). Also,
Here, a Barber pole method was used as a bias method for the magnetoresistive element. For this reason, the end of the electrode in the magnetic sensing part 12 was inclined by 45 ° with respect to the element. The electrode sense in the track width direction is 6 μm, and this sense corresponds to an effective track width. In the above embodiment, the insulating layer was planarized by using the etch-back method. However,
The step due to the magnetoresistance effect element is 0.3 μm or less,
The thickness is smaller than the thickness of the magnetic shield layer formed thereon of 2.0 μm. Also, the step (0.7 μm) on the magnetic pole is smaller than the thickness (2 μm) of the coil conductor. For this reason,
The planarization of the insulating layer is not always necessary.

Embodiment 2 FIG. 2 shows off-track overwrite characteristics of the head and crosstalk characteristics due to adjacent tracks. The parameter is the ratio between the step (d) of the lower magnetic pole and its thickness (t). Above the figure, schematic diagrams of the magnetic pole carrying of the recording head viewed from the medium facing surface at each ratio are shown. Since the side surface of the magnetic pole is tapered during processing, the cross section is trapezoidal. In the results shown in the figure, the off-track amount is set to 10% of the track width. When the step amount (d) increases, the off-track overwrite characteristics are improved. This is because the magnetic flux at the time of recording concentrates on the recording track width portion as the step increases, and the recording bleeding decreases. Further, the crosstalk characteristic of the adjacent track also depends on the amount of the step, and as the step increases, the S / N ratio decreases. This is because the shield effect is reduced since the thickness of the shield layer is reduced as d increases. In particular, when d / t is 1, that is, when the width of the magnetic shield layer coincides with the upper magnetic pole, the end of the magnetoresistive element is not shielded, so that the S / N is significantly deteriorated. Here, the S / N required for the operation of the magnetic head
If 26 dB is taken as the lower limit of, the result is as shown in the figure. Therefore, there is an optimum value for the step amount (d), and the step amount (d) is 2
In the case of a permalloy having a thickness of μm, it is about 0.6 μm to 1.4.
It can be seen that it is in the range of μm.

Note that this value depends on the angle of the tapered cross section. That is, as the side surface becomes steeper, the recording blur decreases, and the off-track overwrite characteristics are improved. Further, when the upper magnetic pole is formed by a plating method, the cross section has an inversely tapered shape. In this case, recording blur can be further reduced. Here, naturally, the above value depends on the magnetic properties (saturation magnetic flux density BS, magnetic permeability η) and the film thickness of the magnetic film used for the magnetic pole.

Embodiment 3 Another embodiment of the present invention will be described with reference to FIG. FIG. 1A is a plan view of a magnetic head, and FIG. 2B is a cross-sectional view as viewed from a surface facing the medium, showing a head having a structure in which a magnetoresistive element is sandwiched between upper and lower magnetic poles for recording. First, a lower magnetic pole 13 for a recording head, which also serves as a magnetic shield layer, is formed on the base 1. Next, the insulating layer 14 is formed, and the magnetoresistance effect element 4 is provided thereon. Subsequently, a conductor layer 9 serving as a coil of the recording head is provided. After laminating the insulating layer 15 thereon, a groove 17 corresponding to the recording track width is formed. Subsequently, magnetic films are laminated to form an upper magnetic pole / magnetic shield film 18. Here, as the magnetic film, a Co-based amorphous alloy having a saturation magnetic flux density of 1.3 T was used. The film thickness is 1.
5 μm. The size of the lower magnetic pole in the track width direction is 50
μm, the width of the upper magnetic pole is 45 μm, and the width of the groove is 6 μm. Alumina formed by a sputtering method was used for the insulating layers 14 and 15. Each film thickness is between the upper and lower magnetic poles.
4 μm and 0.4 μm. The magnetoresistance effect element 4 was formed of permalloy having a thickness of 40 nm. As the bias method, the Barber pole method was used as in the first embodiment. The shape of the element is 30 μm long and 12 μm high
It is. The electrode layer 11 of the magnetoresistive element has a thickness of 0.2.
A1 of μm was used. The distance between the electrodes in the track width direction, that is, the track width is 4 μm. In order to change the depth of the groove, the thickness of the insulating layer 15 needs to be changed in advance according to the depth.

Using this head, off-track overwrite characteristics and adjacent track crosstalk characteristics were evaluated in the same manner as in Example 2 using the groove depth as a parameter. As a result, when the depth of the groove is in the range of 0.5 μm to 1.0 μm, 26 d
It was found that an S / N of B or more was obtained. By providing a groove, that is, a step, in the magnetic shield layer, the off-track overwrite characteristics and the adjacent track crosstalk are improved. In this embodiment, no step is provided in the magnetic shield layer 13 also serving as the lower magnetic pole, but a step can be provided in this layer. Also in this case, the effect of the step appears, and the off-track overwrite characteristics and the adjacent track crosstalk are improved.

However, since the magnetoresistance effect element needs to be formed on a flat portion, it is necessary to flatten the insulating layer 14 by an etch-back method.

Embodiment 4 As another embodiment of the present invention, a magnetoresistance effect element using another bias method can be used. For example, a magneto-resistance effect element using a conventionally known mutual bias, current bias, or permanent magnet bias can be used. Further, as the shape of the element, not only the rectangular shape described in the present embodiment but also an element having a closed magnetic circuit structure having a small gap can be used.

In each of the embodiments described above, the magnetoresistive effect element having high reproducing efficiency is used as the reproducing head. However, a conventional inductive head may be used.

In this case, by increasing the track width of the recording head and narrowing the track width of the reproducing head,
The off-track overwrite characteristics and the crosstalk between tracks can be reduced. Therefore, by providing a step in the magnetic pole serving both for recording and reading, and by matching the upper and lower dimensions of the step with the respective track widths, the characteristics can be improved.

Embodiment 5 Next, an embodiment in which the relative magnetic permeability and the saturation magnetic flux density are different between the upper part and the lower part of the shared magnetic film will be described. FIG. 4 shows a recording magnetic pole laminated on a magnetoresistive read head. As in the case of the first embodiment, the reproducing head forms the magnetoresistive element 4 made of a thin-film permalloy between the shield layers 2 and 6 made of permalloy through an insulating layer. Next, the lower magnetic pole 19 of the recording head is formed on the upper magnetic shield layer 6. At this time, the magnetic shield is permalloy having a thickness of 0.7 μm. Magnetic pole 19
Used was CoTaZr having a saturation magnetic flux density of 1.3T. The film thickness was 0.8 μm. Thereafter, a coil is formed via the insulating layer 8, and the upper magnetic pole 7 is formed thereon. This magnetic pole is formed of CoTaZr having a thickness of 1.5 μm. Here, the dimensions of each magnetic layer in the track width direction are 100 μm for the lower shield layer 2, 90 μm for the upper shield layer 6, 8 μm for the lower magnetic pole 19, and 6 μm for the upper magnetic pole 7.

The thickness of the insulating layer and the structure of the magnetoresistive element are the same as in the first embodiment.

As described above, since the bleeding of the recording magnetic field can be suppressed by increasing the saturation magnetic flux density of the magnetic pole on the recording head side, the recording characteristics can be improved.

Embodiment 6 Next, an embodiment in which an inductive head is used as the recording / reproducing head will be described with reference to FIG. First,
The recording magnetic poles 19 and 7 are formed on the base 1.

The track width at this time is 10 μm each.
m, 8 μm. The film thickness is 3 μm in each case. The material is CoTaZr having a saturation magnetic flux density of 1.3T. Permalloy is stacked thereon as the magnetic poles 20 and 21 for the reproducing head. The thickness of each film is 1 μm. The dimension of the read head in the track width direction is 5
μm, and the upper magnetic pole 21 is 4 μm. At this time, the relative magnetic permeability was 1200 for CoTaZr and 20 for Permalloy.
00. The thicknesses of the insulating layers 3 and 5 serving as the gap layers are 1.5 μm and 0.2 μm, respectively. The number of turns of the recording and reproducing head coils is 8 turns and 24 turns, respectively.

As described above, by increasing the saturation magnetic flux density of the magnetic pole on the recording head side and increasing the magnetic permeability of the magnetic pole on the reproducing head side, bleeding of the recording magnetic field can be suppressed.
The recording characteristics can be improved. Further, since the magnetic flux at the time of reproduction is concentrated on the magnetic pole for reproduction, the reproduction can be performed efficiently.

[0022]

According to the present invention, the recording bleeding at the magnetic pole tip of the recording head is suppressed, and the off-track overwrite characteristics are improved. Further, since the magnetic shield layer can cover the end of the magnetoresistive element, crosstalk between tracks can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view of a magnetic head illustrating an embodiment of the present invention.

FIG. 2 is a graph showing off-track overwrite characteristics and adjacent track crosstalk characteristics in the magnetic head of the present invention.

FIG. 3 is a plan view and a cross-sectional view of a head showing another different embodiment.

FIG. 4 is a sectional view of a head showing another different embodiment.

FIG. 5 is a sectional view of a head showing another different embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Base | substrate, 2,6,13,18 ... Magnetic pole and magnetic shield layer, 3,5,8,10,14,15 ... Insulating layer, 4 ... Magnetoresistance effect element, 7 ... Upper pole, 9 ... Coil conductor, 11 ...
Electrode layer, 12: magnetic sensing part, 16: stepped part, 17: groove, 1
9, 20, 21 ... magnetic poles.

Continuing on the front page (72) Inventor Kazuo Shiiki 1-280 Higashi Koikebo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory

Claims (3)

[Claims] In a magnetic head in which a recording head and a reproducing head are separated and combined, a dimension in a track width direction of a magnetic layer sharing the recording head magnetic pole and a magnetic shield layer of the reproducing head is determined by a film thickness of the magnetic layer. A magnetic head characterized by being different in an upper part and a lower part in a direction. 2. The common magnetic layer has a step, and the upper and lower sides of the step have a dimension in a track width direction.
2. The magnetic head according to claim 1, wherein a track width of the magnetic head or a width of the magnetic shield layer is defined. 3. The magnetic head according to claim 5, wherein said reproducing element is a magnetoresistive element.