JP3280057B2 - 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 a thin-film magnetic head in which a reproducing head comprising a magnetoresistive element and, for example, an inductive recording head are integrated.

2. Description of the Related Art In a magnetic disk drive, the diameter of a magnetic disk as a recording medium has been reduced. Accordingly, a thin film magnetic head incorporating a magnetoresistive element capable of obtaining a large reproduction output even when the relative moving speed with respect to the magnetic disk is low has been attracting attention.

[0003]

2. Description of the Related Art A magnetoresistive element can be used only for reading (reproducing) information from a magnetic recording medium. Therefore, for writing (recording) information, it is necessary to use other electromagnetic conversion means.

[0004] Conventionally, a reproducing head portion comprising a magnetoresistive effect element and a pair of magnetic shield layers (soft magnetic layers) sandwiching the magnetoresistive effect element, and a coil and a pair of magnetic poles (soft magnetic layer constituting a magnetic core). 2. Description of the Related Art A thin-film magnetic head in which an inductive recording head is integrated is known.

In general, this type of composite type thin-film magnetic head has the above-described heads arranged as close as possible to facilitate head position control for recording and reproduction.
In order to have a simple head structure that is advantageous in terms of manufacturing cost,
One magnetic shield layer is configured to also serve as a magnetic pole. That is, one magnetic layer is provided as a component common to both the read head unit and the write head unit.

FIG. 4 is a sectional view showing the structure of a conventional thin film magnetic head 1j. FIG. 1 shows a cross-sectional structure as viewed from the recording medium side. The thin-film magnetic head 1j includes a read head R
This is a composite type head having an H and a recording head section WH, and is composed of a support 11 and the following sections sequentially laminated thereon.

First, a lower magnetic shield layer 12 having a predetermined shape is provided on a support 11, and a nonmagnetic layer 1 is formed thereon.
3, a magnetoresistive element layer (hereinafter, referred to as “MR layer”) 14 and an electrode layer 15 are provided. MR layer 14
Is provided with an upper magnetic shield layer and a dual-purpose magnetic layer 17j serving as a lower magnetic pole via a non-magnetic layer 16,
Further, an upper magnetic pole 20 is provided thereover via a gap layer 19. Then, a protective film 23 is provided as an uppermost layer.

[0008] Magnetic shield layer 12 and dual-purpose magnetic layer 17j
Shields an external magnetic field from the MR layer 14. The dual-purpose magnetic layer 17j and the upper magnetic pole 20 are magnetically coupled at a portion (not shown) to form a magnetic core MC for guiding a magnetic flux generated by a coil (not shown) to the recording medium. The magnetic shield layer 12 and the dual-purpose magnetic layer 17
j and the magnetic pole 20 are each formed of a soft magnetic layer having a uniform magnetic property.

[0009]

In the conventional thin-film magnetic head 1j, in the MR layer 14, the dual-purpose magnetic layer 1 associated with recording is used.
There is a problem that the influence of the magnetization of 7j appears relatively remarkably. That is, a so-called popcorn is included in the reproduction signal of the MR layer 14 due to the wiggle phenomenon in which the domain wall moves irregularly and discontinuously in the combined magnetic layer 17j, and particularly, the phenomenon in which the domain wall moves irregularly immediately after recording. There is a problem that noise such as noise is easily superimposed.

In order to solve such a problem, it is conceivable to arrange the reproducing head portion RH and the recording head portion WH magnetically separated via a non-magnetic layer. You will lose the advantages of simplification.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to improve magnetic head performance by suppressing magnetic interference between a recording unit and a reproducing unit.

[0012]

According to a first aspect of the present invention, there is provided a head for solving the above-mentioned problems, as shown in FIG. 1, a magnetoresistive effect element and a pair of magnetic shield layers sandwiching the element. 17. A thin-film magnetic head 1 having a read head RH comprising a magnetic head 17 and a write head WH having the one magnetic shield layer 17 as a part of a magnetic core MC, wherein the magnetic shield layer 17 has a thickness of Central part 17 of direction
2 comprises a soft magnetic layer in which the magnetic properties of the upper part 173 and the lower part 171 are deteriorated.

According to a second aspect of the present invention, there is provided a head including a magnetoresistive element and a pair of magnetic shield layers sandwiching the element.
A thin-film magnetic head 1B having a read head RH composed of a magnetic head MC and a read head RH composed of the magnetic shield layer 17B. The magnetic characteristics of the central portion 172 in the thickness direction are deteriorated with respect to the magnetic characteristics of the upper portion 173B and the lower portion 171 and the planar shape of the upper portion 173B is made to correspond to the planar shape of the magnetic pole 20 constituting the magnetic core MC. It consists of a magnetic layer.

In the head according to the third aspect of the present invention, the magnetic permeability of the central portion 172 is smaller than that of the upper portion 173, 173B and the lower portion 171.

[0015]

The magnetic shield layers 17 and 17B are soft magnetic layers which are used for both reproduction and recording as a whole. Due to deterioration (for example, low magnetic permeability), the magnetization during recording mainly occurs locally in the upper portion 173. Therefore, in the magnetoresistive element 14,
The effect of the domain wall motion accompanying the magnetization of the magnetic shield layers 17 and 17B hardly appears.

The upper portion 173 of the magnetic shield layer 17B
By associating the planar shape of B with the magnetic pole 20 used only for recording, that is, by making the planar shape of the upper portion 173B and the magnetic pole 20 substantially the same at least in the vicinity of the recording medium facing portion, the magnetic flux falls within the range of the recording width. It is possible to concentrate, and it is possible to suppress the bleeding of the recording due to the spread of the magnetic flux.

[0017]

1 and 2 show the structure of a thin-film magnetic head 1 according to the present invention. FIG. 1 shows a cross-sectional structure as viewed from the recording medium side, and corresponds to a cross-section taken along line II of FIG. 2B. FIG. 2A shows a cross-sectional structure viewed from the right side of FIG.
FIG. 2B corresponds to a cross section taken along the line AA in FIG. FIG. 2B shows a planar shape and an arrangement relationship of main components. In these figures, components having the same functions as those in FIG. 4 are denoted by the same reference numerals, and components corresponding to FIG. 4 are denoted by reference numerals without the suffix “j”. .

First, referring to FIG.
Is a composite type head having a reproducing head RH due to a magnetoresistance effect and a recording head WH due to electromagnetic induction, and is made of a soft magnetic material (a high magnetic permeability material) such as a non-magnetic support 11 and permalloy. Lower magnetic shield layer 1
2. The MR layer 14 sandwiched between the non-magnetic layers 13 and 16, the upper magnetic shield layer (hereinafter, also referred to as a "combined magnetic layer") 17 made of one kind of magnetic material also used as the lower magnetic pole, and silicon dioxide. It comprises a gap layer 19, a spiral coil 22, an interlayer insulator 21 such as a thermosetting resin covering the coil 22, an upper magnetic pole 20, a protective film 23, and the like.

The dual-purpose magnetic layer 17 and the upper magnetic pole 20 are integrated at a contact portion 30 so as to form a magnetic core MC. The inner end and the outer end of the coil 22 are respectively connected to external connection terminals (not shown). In FIG. 2, the illustration of the electrode layer 15 (see FIG. 1) that overlaps the MR layer 14 is omitted.

As shown in FIG. 2B, the planar shape of the upper magnetic pole 20 is such that the width of the gap (left end in the figure) defining the track width w is narrower than the other. . On the other hand, when configuring the magnetic core MC, the magnetic poles 20
The planar shape of the dual-purpose magnetic layer 17 that is paired with the track width w
Since it is necessary to completely cover the longer dimension MR layer 14, the width of the gap portion is set to the same shape as the other portions.
That is, the dual-purpose magnetic layer 17 has a region E17b that does not face the magnetic pole 20 as shown by hatching in the figure, and the width of the dual-purpose magnetic layer 17 on the surface facing the recording medium is larger than the width of the magnetic pole 20.

As shown in FIG. 1, the dual-purpose magnetic layer 17 of the thin-film magnetic head 1 has a magnetic property of the central portion 172 in the thickness direction over the entire area in the plane direction.
And a soft magnetic layer (total film thickness of about 2 to 4 μm) deteriorated with respect to the magnetic properties of the lower portion 171. That is, in the dual-purpose magnetic layer 17, the magnetic permeability of the central portion 172 is
3 and the lower part 171.

For this reason, in the dual-purpose magnetic layer 17, the entirety including the central portion 172 has a function of shielding the external magnetic field from the MR layer 14.
Since the magnetic core 73 and the lower part 171 are magnetically separated (but not completely separated), the role of the magnetic core MC is that of the upper part 173 facing the magnetic pole 20 and magnetically coupled.
Will be mainly responsible. The lower part 171 and the central part 17
2 and the upper portion 173 have substantially the same thickness.

Such a dual-purpose magnetic layer 17 can be easily formed by using a thin film technique. For example, the material of the dual-purpose magnetic layer 17 is a nickel-iron (Ni-Fe) magnetic alloy, and the lower portion 171, the central portion 172,
And the upper portion 173 can be continuously formed. However, at this time, the applied current density of the plating condition is changed between the time of forming the lower portion 171 and the upper portion 173 and the time of forming the central portion 172. As a result, there is a difference in the composition relating to the magnetic permeability between the central portion 172 and the other portions. Therefore, if the set value of the applied current density in each stage is appropriately selected, the permeability of the central portion 172 in the thickness direction can be improved. The dual-purpose magnetic layer 17 having a lower magnetic susceptibility than other portions can be obtained.

When a sputtering method is used as a film forming technique, sputtering conditions such as a degree of vacuum (gas pressure) or a bias voltage are changed during continuous film formation to partially lower the crystallinity of the film. Thus, the desired dual-purpose magnetic layer 17
Can be obtained.

The thin-film magnetic head 1 configured as described above
Thus, in the MR layer 14, the effect of domain wall motion accompanying the magnetization of the dual-purpose magnetic layer 17 due to electromagnetic induction hardly appears, and a good reproduced waveform can be obtained.

FIG. 3 is a sectional view showing the structure of a thin-film magnetic head 1B according to another embodiment of the present invention. In the figure, components having the same functions as those in FIGS. 1, 2, and 4 are denoted by the same reference numerals regardless of the difference in shape, and description thereof is omitted.

The thin-film magnetic head 1B also has a read head RH.
And a combined magnetic layer 17B which is a common component of the recording head unit WH. The dual-purpose magnetic layer 17B
Like the dual-purpose magnetic layer 17 of the thin-film magnetic head 1 described above, the thin-film magnetic head 1 is formed of a soft magnetic layer in which the magnetic characteristics of the central portion 172 in the thickness direction are deteriorated with respect to those of the upper portion 173B and the lower portion 171.

In the thin-film magnetic head 1B, the dual-purpose magnetic layer 17
B, the planar shape of the upper portion 173B, that is, the planar shape of the portion substantially functioning as the magnetic core MC is the magnetic pole 2
0 is associated with the plane shape. That is, the upper 17
The planar shape of 3 </ b> B is almost the same as the shape of the magnetic pole 20.

As a result, during recording, the magnetic flux concentrates within the range of the track width w, so that the recording bleeding caused by the spread of the magnetic flux to the region E17b described with reference to FIG. 2B can be suppressed. At the time of reproduction, shielding is performed mainly in the same range as the magnetic shield layer 12 by the lower portion 171, thereby preventing superposition of noise caused by an external magnetic field.

In manufacturing the thin-film magnetic head 1B, M
After covering the R layer 14 and the electrode layer 15 with the non-magnetic layer 16, the dual-purpose magnetic layer 17B is formed as follows. First,
A soft magnetic layer having a three-layer structure is formed on the non-magnetic layer 16 in terms of magnetic characteristics by changing the film forming conditions during the film forming process as described above using an electrolytic plating method or a sputtering method. Is patterned into the same shape as the magnetic shield layer 12.

Next, a silicon dioxide film serving as a gap layer 19 is provided by a sputtering method so as to cover the entire surface of the soft magnetic layer after patterning including the surface of the nonmagnetic layer 16, and after the coil 22 and the like are provided. A magnetic layer to be the upper magnetic pole 20 is provided on the silicon dioxide film.

Subsequently, a resist layer having a shape corresponding to the magnetic pole 20 is provided, and this resist layer is used as an etching mask to form a magnetic layer serving as the magnetic pole 20, a silicon dioxide film serving as the gap layer 19, and a dual-purpose magnetic layer 17B. The resulting soft magnetic layer is collectively etched (patterned) by ion milling.

The etching is terminated when a portion of the soft magnetic layer having deteriorated magnetic properties (a portion corresponding to the central portion 172) is exposed. Thereby, the dual-purpose magnetic layer 17B having the above-described structure is obtained. After that, the protective layer 23 is provided by removing the resist layer, and the thin-film magnetic head 1B
To complete.

According to the above-described embodiment, by reducing the magnetic permeability, the central portion 17 of the dual-purpose magnetic layers 17, 17b can be formed.
Since the magnetic characteristics of No. 2 are deteriorated, the dual-purpose magnetic layers 17 and 17b having a three-layer structure can be provided by one film forming method and a continuous film forming process only by changing the film forming conditions. The productivity of the thin film magnetic heads 1 and 1B can be improved.

In the above embodiment, the dual-purpose magnetic layer 17,
As a method for deteriorating the magnetic characteristics of the central portion 172 of the 17b, metal ions such as chromium (Cr), niobium (Nb), and zirconium (Zr) are introduced as impurities using, for example, an ion implantation method, and the saturation magnetic flux is locally localized. The density may be reduced.

[0036]

According to the present invention, magnetic interference between the recording unit and the reproducing unit can be suppressed, and the head performance can be improved.

According to the second aspect of the present invention, it is possible to prevent recording bleeding. According to the third aspect of the present invention, the formation of the magnetic layer can be facilitated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a thin-film magnetic head according to the present invention.

FIG. 2 is a diagram showing a structure of a thin-film magnetic head according to the present invention.

FIG. 3 is a sectional view showing a structure of a thin-film magnetic head according to another embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of a conventional thin film magnetic head.

[Explanation of symbols]

 Reference Signs List 1 thin-film magnetic head 14 MR layer (magnetoresistive element) 12 magnetic shield layer 17 dual-purpose magnetic layer (magnetic shield layer) 173 upper part 172 central part 171 lower RH reproducing head part WH recording head part MC magnetic core 1B thin-film magnetic head 17B Magnetic layer (magnetic shield layer) 173B Upper 20 Upper magnetic pole (magnetic pole)

Claims (3)

(57) [Claims] 1. A read head (RH) comprising a magnetoresistive element (14) and a pair of magnetic shield layers (12) and (17) sandwiching the element, and the one magnetic shield layer (17).
Head part (WH) that makes a part of magnetic core (MC)
Wherein the magnetic shield layer (17) is provided at a central portion (1) in a thickness direction.
The magnetic properties of 72) are changed to the upper part (173) and the lower part (171).
A thin film magnetic head comprising a soft magnetic layer degraded with respect to the magnetic characteristics of the above. 2. A read head (RH) comprising a magnetoresistive element (14) and a pair of magnetic shield layers (12) (17B) sandwiching the element, and the one magnetic shield layer (17).
B) as a part of a magnetic core (MC), a recording head (W)
H), wherein the magnetic shield layer (17B) changes the magnetic properties of the central part (172) in the thickness direction with the upper part (173B) and the lower part (1B).
71) It is characterized by comprising a soft magnetic layer which degrades the magnetic characteristics of (71) and in which the planar shape of the upper portion (173B) corresponds to the planar shape of the magnetic pole (20) constituting the magnetic core (MC). Thin film magnetic head. 3. The thin-film magnetic head (1, 1B) according to claim 1, wherein the magnetic permeability of the central portion (172) is set to the upper portion (173, 1B).
73B) and a thin film magnetic head which is smaller than the lower part (171).