JP3082347B2 - Magnetoresistive 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 magnetoresistive thin film magnetic head.

[0002]

2. Description of the Related Art As a reproducing magnetic head of various magnetic heads, for example, a magnetic recording / reproducing head of a hard disk drive, a magnetoresistive effect type magnetic head (hereinafter referred to as an MR type magnetic head) having excellent short wavelength sensitivity is used. is there.

[0003] In this MR type thin film magnetic head, adopting a shield type configuration is advantageous in improving resolution.

An MR type reproducing thin film magnetic head of this kind having a shield type configuration may be of a composite type thin film magnetic head configuration integrally formed with an induction type so-called inductive type magnetic head as a recording magnetic head.

For example, FIGS. 10, 11 and 12 each show a schematic plan view of this type of composite type MR thin film magnetic head, and FIG. 10 shows a plan view taken along line BB and line CC of FIG. As shown in the cross-sectional view, for example, in the case of forming a floating type magnetic head, a slider itself floating by an air flow according to the rotation of a magnetic recording medium such as a hard disk, or a substrate made of a substrate attached to the slider A lower thin-film magnetic core 3 and an upper thin-film magnetic core 4 are stacked on top of each other, and between the front ends of these thin-film magnetic cores 3 and 4, a surface facing or facing a magnetic recording medium, ie, a floating magnetic head. Are formed so as to form a magnetic gap g facing the ABS (air bearing surface) 2. A magnetoresistive film having a magnetoresistive effect thin film (hereinafter referred to as an MR thin film) between the lower thin film magnetic core 3 and the upper thin film magnetic core 4 within the magnetic gap g, that is, behind the magnetic gap g. An effect magnetic sensing part (hereinafter referred to as MR magnetic sensing part) 5 is arranged and formed. Reference numerals 15a and 15b denote electrodes formed on both ends of the MR magnetic sensing portion 5.

An insulating layer 6 is further provided on the MR sensing part 5.
A bias conductor 7 formed of a thin film conductive layer is formed across the MR magnetic sensing portion 5 through the via hole.

The upper thin-film magnetic core 4 is magnetically coupled at its rear end to the lower thin-film magnetic core 3 through, for example, a window formed in the insulating layer 6, and the lower and upper thin-film magnetic cores 3 and 4 provide a magnetic gap g. Is included in the magnetic path.

For example, at the same time when the bias conductor 7 is formed, the upper thin-film magnetic core 4 and the lower thin-film magnetic core 3 are mutually magnetically connected by a similar thin-film conductive layer, for example, on the lower thin-film magnetic core via the insulating layer 6. The head winding 8 is formed in a spiral pattern, for example, so as to surround a rear end portion connected to the head winding 8.

In such a thin-film magnetic head, a magnetic layer formed between the front ends of the lower and upper thin-film magnetic cores 3 and 4 facing the surface facing or facing the magnetic recording medium, for example, the ABS 2. The shield type MR magnetic head in which the MR magnetic sensing part 5 is arranged in the gap g and the magnetic cores 3 and 4 are configured as magnetic shields is configured.

That is, the signal magnetic field recorded on the magnetic recording medium through the magnetic gap g is applied to the MR magnetic sensing unit 5. On the other hand, both electrodes 15a and 1
With the sense current i _S is energized between 5b, the required current is energized to the bias conductor 7, which magnetic field generated by the given in MR magnetic sensing section 5 as required magnetization state in MR magnetic sensing section 5 Operate in a magnetoresistive characteristic region exhibiting high sensitivity and exhibiting linearity, and as described above, through the magnetic gap g, changes in the magnetoresistance due to the signal magnetic field given from the magnetic recording medium are applied to the electrodes 15a and 15a.
This is detected as a voltage change between b.

During recording on the magnetic recording medium, the current supply to the bias conductor 5 is cut off, and the supply of the sense current i _S to the MR sensing section 5 is cut off. A required current is applied in accordance with the recorded information, whereby the magnetic field generated in the closed magnetic path by the lower and upper thin-film magnetic cores 3 and 4 is taken out of the magnetic gap g and magnetic recording on the magnetic recording medium is performed. Done. That is,
A composite magnetic head of the MR reproducing magnetic head and the inductive recording magnetic head is constructed.

In constructing a composite magnetic head using an inductive recording magnetic head including such an MR thin-film magnetic head, FIGS. 13 to 15 are plan views showing one manufacturing process thereof, and FIGS. As shown in the sectional views on the line and the line CC, the base 1 is plated with a magnetic alloy such as FeNi under the application of a magnetic field by, for example, well-known frame plating, and then the frame made of photoresist or the like is removed. Then, the unnecessary portion of the magnetic alloy outside the frame is removed by etching to form the lower thin-film magnetic core 3.

The lower thin film 3 is generally formed sufficiently large compared to the track width W _T of the finally obtained magnetic gap g, that is, has a large area that finally includes the entire area of the pattern of the upper thin film magnetic core 4. . Then, the non-magnetic insulating layer 6 such as SiO ₂ or Al ₂ O ₃ is entirely covered with the non-magnetic insulating layer 6 such as SiO ₂ or Al ₂ O ₃ by covering the lower thin-film magnetic core 3 formed in a pattern having a required large area. Forming
The surface is flattened. Then, the above-mentioned MR magnetic sensing portion 5, electrodes 15a and 15b and the like are formed on the flat surface, and a bias conductor 7 is further formed thereon via an insulating layer 6.
And a head winding 8 and the like, and an upper thin-film magnetic core 4 is further formed on the upper thin-film magnetic core 4 via an insulating layer 6, for example, through a window formed in the insulating layer 6. It is formed so as to be magnetically coupled through a magnetic layer or a non-magnetic layer.

10 and FIG. 1 are polished from the front side to a position indicated by a chain line a in FIGS.
An ABS surface 2 indicated by reference numeral 2 is formed.

In this case, the upper thin-film magnetic core 4 is formed by
Similarly, a magnetic alloy such as FeNi is formed by, for example, plating the entire surface and etching it into a required pattern in a state in which an external magnetic field is applied in a predetermined direction. width has a width corresponding to the required track width W _T narrow constricted portion 4a is formed in the formed pattern, as shown in FIG. 13 in the formation of the gap g.

[0016] However, when the track width W _T and 10μm or less in such MR thin-film magnetic head obtained by the Barkhausen noise occurs a problem that becomes large.

Further, the MR type thin film magnetic head having such a configuration has a problem that its characteristics are apt to vary.

As a result of various experimental studies, the present inventors have found that when the lower thin-film magnetic core 3 is formed into a large-area magnetic core pattern as described above, the MR magnetic sensing part 5 and the upper layer It has been determined that the magnetic domain structure of the thin film magnetic core 4 is disturbed.

That is, in the MR magnetic sensing part 5 in the MR type thin film head having the above-described structure, it is necessary that the easy axis of magnetization is directed in the track width direction in order to improve the sensitivity.

In order to orient the easy axis of magnetization of the MR magnetic sensing portion 5a in the track width direction, an external magnetic field is applied to the MR magnetic sensing portion 5 in the track width direction at the time of deposition or deposition of an MR thin film. Is applied.

However, since the external magnetic field has a width of several inches in the base 1, the above-mentioned external magnetic field in the portion where the MR magnetic sensing portion 5 is formed is not so strong. If the lower thin-film magnetic core 3 having a wide width exists below the lower thin-film magnetic core 3, the magnetic core 3 is a relatively thick magnetic layer having a thickness of usually several μm. The magnetic field structure of the MR thin film causes
As shown in FIG. 16, an unstable and distorted shape inclined with respect to the track width direction is obtained.

Further, as described above, if the lower thin-film magnetic core 3 is wide, even when the upper thin-film magnetic core 4 is similarly formed thereon, the plating of the magnetic material is performed in a state where an external magnetic field is applied. In the same manner as described above, the magnetic domain structure is greatly affected by the lower thin-film magnetic core 3 as shown in FIG. 17, and the magnetic domains in the constricted portion 4a forming the magnetic gap g are particularly along the track width direction. Instead, it was found that the Barkhausen noise becomes large due to the predominant magnetization state in the gap depth direction.

Furthermore, also when to perform provision of the track width W _T by the upper layer of the thin-film magnetic core 4, this pattern it is necessary to perform on the basis of the formation position of the MR thin film 3 formed on the lower layer However, in practice, a bias conductor or a head winding is formed and substantially M
Setting the upper thin film magnetic core accurately with a predetermined positional relationship with the MR magnetic sensing part with the distance to the R thin film being large causes a decrease in accuracy, and this causes variations in characteristics. It was determined that it was an invitation.

[0024]

SUMMARY OF THE INVENTION The present invention relates to the aforementioned M
In the R-type thin-film magnetic head, even when the track width is reduced to, for example, 10 μm or less, Barkhausen noise can be sufficiently reduced, and an MR-type thin-film magnetic head having stable characteristics can be obtained. It is to be.

That is, the present invention provides an MR type thin film magnetic device capable of reducing the above-described Barkhausen noise, and further achieving uniform and stable characteristics based on the new findings based on the results of the above research and consideration. In addition, in the present invention, the reproducing head is an MR type head, and the upper and lower cores 3 and 4 at the time of the reproduction are transferred to the MR magnetic sensing unit 5 by a magnetic recording medium. It is an invention made by skillfully capturing the feature of having a function of shielding an unnecessary magnetic field other than the magnetic field to be read from the memory.

That is, for example, Japanese Patent Laid-Open No.
In this publication, a structure in which the width of a pair of magnetic poles forming a gap G is changed is disclosed, but in this case, reading from a magnetic recording medium, that is, reading from a magnetic recording medium, that is, reproducing is performed.
Since the head is of an inductive type rather than a magnetic head, that is, a pair of magnetic poles constituting the gap G picks up a signal magnetic field from the magnetic recording medium, a so-called magnetic field between the edges of both magnetic poles during reproduction is used. The fact that fringing is a problem and how to deal with it limits the difference in the width of the pair of magnetic poles.

The present invention has a completely different object and idea from the above, and has an MR type reproducing head structure which does not require consideration of this fringing. And noise can be reduced.

[0028]

FIG. 11 is a plan view of an MR type thin film magnetic head according to the present invention, and FIGS. 2 and 3 show the MR thin film magnetic head on the line BB and the line CC of FIG. 1, respectively. As shown in each cross-sectional view, a lower thin-film magnetic core 3 and an upper thin-film magnetic core 4 on a substrate 1 are in contact with or opposed to a magnetic recording medium (not shown) between front ends thereof, for example, a floating type magnetic core. The head is laminated so as to form a magnetic gap g on the ABS 2 of the slider as desired, and an MR magnetic sensing part 5 is arranged between the lower and upper thin-film magnetic cores 3 and 4 in the magnetic gap g.

The width of the front end to form a magnetic gap g of the lower thin film magnetic core 3 has a front end and a width defining a track width W _T of the magnetic gap g, to form a magnetic gap g of the upper thin film magnetic core 4 Is selected to be sufficiently larger than the width of the similar front end of the lower thin-film magnetic core 3.

[0030]

SUMMARY OF] According to the present invention the above-described configuration performs the prescribed track width by the underlying thin film magnetic core 3, namely arrangement was selected width of the magnetic gap forming portion in a narrow width corresponding to the track width W _T and In forming the lower thin-film magnetic core 3, further, in forming the MR magnetic sensing portion 5, that is, in forming the MR thin film, a predetermined external magnetic field is applied to perform plating, vapor deposition, sputtering, or the like.
Since there is no wide magnetic core in the lower layer, a good magnetic domain structure can be formed.

FIGS. 4 and 5 schematically show the MR magnetic sensing part 5 and the magnetic domain structure, according to which the narrow width of the narrow part 3C forming the magnetic gap g of the lower thin film magnetic core 3 is reduced. In other words, the magnetic domain can be formed well in the portion, that is, in the track width direction, and the magnetic domain can also be aligned in the track width direction in the MR sensing section 5 so that the easy axis of magnetization can be set to the track width. Barkhausen noise can be reduced, and sensitivity can be improved and stabilized.

In this case, since the configuration of the present invention is an MR type reproducing head, there is no possibility of fringing. Therefore, the width of the front end of the upper thin-film magnetic core 4 is set to be equal to the width of the front end of the lower thin-film magnetic core 3. It can be made sufficiently large without being restricted by the difference from the width of the end. Further, according to the present invention, an MR magnetic sensing part 5, that is, an MR type thin film is formed on the lower thin-film magnetic core 3. Since they are formed close to each other, the positional relationship between the two can be accurately set, whereby an MR type thin film magnetic head having excellent reproducibility without variation in characteristics can be constructed.

[0033]

1 to 3 and FIGS. 6 to 8, an embodiment in which the present invention is applied to a composite thin film magnetic head comprising an MR reproducing thin film magnetic head and a dielectric recording thin film magnetic head. Will be described in detail.

FIG. 6 is a schematic enlarged plan view showing one step of the manufacturing process of the device of the present invention, and FIGS.
FIG. 2 shows a cross-sectional view taken along a line B and a line CC. In this case, when applied to the base 1, for example, a flying magnetic head, a lower layer made of a magnetic material such as FeNi is provided in a required pattern on the base 1 made of the flying slider itself or a substrate attached thereto. The thin film magnetic core 3 is plated by a known so-called frame plating in a state where an external magnetic field is applied in a required track width direction, for example, and thereafter, a pattern such as a photoresist that forms the frame is removed, and further unnecessary portions around the frame are removed. The plating layer is removed by etching.

As shown in FIG. 6, the lower thin-film magnetic core 3 has a required track width W _T, for example, W _T ≦ 10 μm.
It is possible to form a pattern having a constricted portion 3C having W _T = 4 to 6 μm, a wide front portion 3A wider than the narrow portion 3C, and a wide rear portion 3B wider than the narrow portion 3C.

Then, an insulating layer 6 of SiO ₂ , Al ₂ O _3, or the like is applied over the entire surface of the lower thin-film magnetic core 3 thus formed by a sputter layer, and the surface thereof is planarized by flat polishing. Surface.

Then, N is placed on the flattened insulating layer 6.
An MR type magnetic sensing portion 5 made of an MR thin film of iFe, NiCo, NiFeCo or the like is formed to have a width of, for example, 3 to 5 μm smaller than the width of the front end of the lower thin film magnetic core 3 described above. This M
For example, as shown in a schematic sectional view of FIG. 9, the R-type magneto-sensitive portion 5 has a plurality of magneto-statically coupled portions with almost no exchange coupling via a non-insulating thin film 26 made of SiO ₂ or the like. For example, a laminated structure of two MR thin films 25A and 25B can be configured to reduce the Barkhausen noise by avoiding the generation of domain walls by magnetic coupling of the two MR thin films 25A and 25B.

Electrodes 15a and 15b are ohmicly connected to both ends of the MR magnetic sensing portion 5, respectively.
A and 25B are attached so as to be electrically coupled to both ends,
A predetermined sense current is caused to flow between the electrodes 15a and 15b so that a sense current i _s / 2 in the same direction is applied to both MR thin films 25A and 25B of the MR sensing part 5.

Further, the MR magnetic sensing part 5 is covered with SiO
An insulating layer 6 such as a _second layer is formed, and a sense current i _{S of the} MR sensing section 5 is formed.
And the head winding 8 having a required spiral pattern, for example, can be formed at the same time as forming the bias conductor 7 made of a thin film conductive layer in a direction intersecting the current flowing direction, for example, the track width direction. That is, a conductive layer of Cu or the like is formed by plating, sputtering, or the like, and this is formed into a required pattern by etching or the like by photolithography to form the bias conductor 7 and the head winding 8.

Then, a window is opened in the insulating layer 6 on the rear part of the lower thin-film magnetic core 3, and through this window, the upper thin-film magnetic core 4 is magnetically directly or non-magnetic with a required thickness. A desired pattern is formed so as to be magnetically coupled through the layer.

The upper thin-film magnetic core 4 is formed of FeN
A magnetic layer such as i is plated by frame plating or the like or entirely under the application of a required external magnetic field, and then formed into a required pattern by etching using photolithography. In this case, the width of the upper thin-film magnetic core 4 is selected to be a sufficiently large width of at least 2 μm or more even at the narrow front end of the lower thin-film magnetic core 3, the lower layer of the thin-film magnetic core 3 can be a magnetic gap g having a required track width W _T is restricted by the underlying anterior width of the thin-film magnetic core 3 therebetween can be reliably face the upper layer of the thin film magnetic core 4, Ensure stable magnetic properties.

Reference numerals 35a and 35b denote electrodes 15a and 15b, respectively.
b, terminal lead-out portions formed to extend from b, 37a and 37b
Is a terminal lead-out portion derived from both ends of the bias conductor 7;
Reference numerals a and 38b denote terminal lead-out portions extending from or connected to both ends of the head winding 8, respectively. These terminals are used in the same process of the electrodes 15a and 15b, the bias conductor 7, and the head winding 8, respectively. It may be formed by a conductive pattern that extends or is formed by another process.

Then, the base 1 including the lower and upper thin-film magnetic cores 3 and 4 configured as described above is moved from its front end to a position indicated by a chain line a in FIG. Polished to the position to reach ABS surface 2
Together form a 1 to the magnetic gap g having a required track width W _T facing to the ABS surface 2 is formed
A composite thin-film magnetic head shown in FIG. 3 is obtained.

In the above-described example, the present invention is applied to the case where a composite magnetic head of an MR type thin film magnetic head and an inductive type magnetic head is obtained. The present invention can be applied to an MR type thin film magnetic head or the like configured as described above.

[0045]

As described above, according to the present invention, the lower layer
The track width W is determined by the thin-film magnetic core 3. _TStipulate the narrow
MR feeling by having a pattern with a small front end
In forming the magnetic part 5 and the upper thin-film magnetic core 4,
There is no large area thin film magnetic core in the lower layer
Then, under the application of an external magnetic field, the MR sensing part 5 and the upper thin film
By forming the magnetic core 4, magnetic
It has a magnetically sensitive part provided with an easy axis and a good magnetic domain structure.
Thin-film magnetic core 4 can be formed,
Stability characteristics, reduction of Barkhausen noise
Can be measured.

As described above, in the configuration of the present invention, the MR
The upper thin-film magnetic core 4 has a front width of the upper thin-film magnetic core 4 which is not restricted by the difference between the width of the front end of the lower thin-film magnetic core 3 and the width of the front thin-film magnetic core 3. Can be large.

The MR thin film of the MR sensing section 5 aligns the lower thin film magnetic core 3 disposed close to the magnetic gap g defined by the lower thin film magnetic core 3. Therefore, the relationship between the two, that is, the positional relationship between the two can be set with high accuracy in the composite magnetic head of the MR type magnetic head and the induction type magnetic head.

Further, since the definition of the magnetic gap g is formed by the lower thin-film magnetic core 3 formed on the base 1 in a flat state, the pattern of the thin-film magnetic core 3 can be formed with high precision, so that the characteristics are uniform. Thus, it is possible to obtain a practically large benefit such as a stable MR type magnetic head.

[Brief description of the drawings]

FIG. 1 is a plan view of an example of an MR type magnetic head according to the present invention.

FIG. 2 is a sectional view taken along line BB of FIG.

FIG. 3 is a sectional view taken on line CC of FIG. 1;

FIG. 4 is a diagram showing a magnetic domain structure of an MR sensing part.

FIG. 5 is a diagram showing a magnetic domain structure of an upper thin-film magnetic core.

FIG. 6 is a schematic plan view of an example of an MR type thin film magnetic head according to the present invention in a manufacturing step.

FIG. 7 is a sectional view taken on line BB of FIG. 6;

FIG. 8 is a schematic sectional view taken on line CC of FIG. 6;

FIG. 9 is a schematic sectional view of an example of an MR magnetic sensing unit.

FIG. 10 is a schematic plan view of a conventional MR thin-film magnetic head.

FIG. 11 is a sectional view taken along line BB of FIG. 10;

FIG. 12 is a sectional view taken along line CC of FIG. 10;

FIG. 13 is a plan view showing one manufacturing step of a conventional MR thin-film magnetic head.

FIG. 14 is a sectional view taken on line BB of FIG. 13;

FIG. 15 is a cross-sectional view taken along line CC of FIG.

FIG. 16 is a diagram showing a magnetic domain structure of an MR magnetic sensing part of a conventional head.

FIG. 17 is a diagram showing a magnetic domain structure of a thin-film magnetic core of a conventional head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 ABS surface 3 Lower-layer thin-film magnetic core 4 Upper-layer thin-film magnetic core 5 MR magneto-sensitive part 6 Insulating layer g Magnetic gap

Continued on the front page (72) Inventor Kenichiro Tsunewaki 6-5-6 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Magne Products Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 5/39

Claims (1)

(57) [Claims] A lower thin-film magnetic core and an upper thin-film magnetic core are stacked on a substrate so as to form a magnetic gap between each front end facing or facing a magnetic recording medium. A magnetoresistive sensing part is arranged between the upper thin-film magnetic cores in the magnetic gap, and a width of a front end of the lower thin-film magnetic core that forms the magnetic gap is a width that defines a track width of the magnetic gap. The width of the front end of the upper thin-film magnetic core is selected to be larger than the width of the front end of the lower thin-film magnetic core.