JP3344039B2 - Thin film magnetoresistive 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 magnetoresistive head (hereinafter abbreviated as "thin film MR head") used for a magnetic storage device such as a computer.

[0002]

2. Description of the Related Art In recent years, a hard disk device as a magnetic storage device has been required to have a smaller size and a larger capacity year by year, and a track width has become narrower and a high recording density has been tended. Under such circumstances, a thin film MR head provided with a magnetoresistive effect element (hereinafter abbreviated as MR element) has been developed to achieve ultra-high density. The thin film MR head includes a separate type in which a recording core portion and a shield portion of a reproducing portion are separately separated, and a merge type type in which a lower core of the recording core portion also serves as an upper shield of the reproducing portion. The thin film MR head of the merge type has a smaller distance between the recording gap and the reproducing gap than the separate type thin film MR head, and is advantageous for an in-line type hard disk drive. In addition, since the number of steps in the manufacturing process of the thin film MR head is reduced, a merge type thin film MR head (hereinafter, simply referred to as a thin film MR head) has recently been used.

A conventional thin film MR head will be described below. FIG. 8 is a plan view of a main part of a conventional thin film MR head, and FIG. 9 is a sectional view of a main part of a conventional thin film MR head.
1 is a substrate to be a slider, 2 is an insulating film such as alumina laminated on the substrate 1, and 3 is FeN laminated on the insulating film 2.
A lower shield layer made of an i-plated film, 4 is an MR lower gap insulating film made of an alumina film stacked on the lower shield layer 3, and 5 is FeNi for detecting magnetism stacked on the MR lower gap insulating film 4. M consisting of sputtered film
The R element part 6 is an MR upper gap insulating film made of an alumina film laminated on the MR element part 5, the reference numeral 7 is the MR lower gap insulating film 4, the MR element part 5, and the MR upper gap insulating film 6.
8 is an upper shield layer which also serves as a lower core with a FeNi plating film laminated on the read gap 7; 9 is a recording gap made of an alumina layer;
Reference numeral 10 denotes an upper recording core made of a FeNi plating film,
Reference numeral 1 denotes a protective insulating film made of an alumina film laminated on the upper core 10. 9, reference numeral 12 denotes a recording coil of a Cu plating film laminated between the upper shield layer 8 and the upper core 10, reference numeral 13 denotes an insulating resist film, and reference numeral 14 denotes an upper core 10 in direct contact with the upper shield layer 8. This is the back core part.

Here, the back core portion 14 of the upper core 10
Are in direct contact with the upper shield layer 8 and form a recording core portion during recording to facilitate the passage of magnetic flux. Further, the lower shield layer 3 and the upper shield layer 8 are located at substantially parallel positions, and this interval becomes a read gap at the time of reproduction. Therefore, the dimensional accuracy of this interval is an important factor in determining the performance of the thin film MR head. It is.

The operation of the conventional thin film MR head configured as described above will be described below. FIG. 10 is a diagram showing a change in magnetic flux during reproduction of a conventional thin film MR head. 15 is a magnetic disk medium, and 16 is a magnetic flux. A conventional merge type thin film MR head is divided into a recording section and a reproducing section as shown in FIG. 10, but the upper shield layer 8 of the reproducing section plays the role of the lower core of the recording section at the time of recording, so that it has a very high density. Magnetic recording and reproduction are possible.
When information is recorded on the magnetic disk medium 15, an electric current flows through the recording coil 12, the upper core 10 and the upper shield layer 8 form a recording core portion, and the magnetic surface of the magnetic disk medium 15 is formed by the magnetic flux 16. Information is recorded by magnetizing. On the other hand, when reproducing information recorded on the magnetic disk medium 15, a sense current is supplied to the MR element unit 5 and a magnetic flux 16 of the information recorded on the magnetic disk medium 15 is supplied.
Is detected as a change in electric resistance by the reproduction sensing unit of the MR element unit 5, and this is reproduced and output as a change in voltage as shown in FIG. FIG. 11 shows a general thin film M
FIG. 3 is a diagram showing a reproduction signal of an R head. In FIG. 11, Bpp is called a baseline noise, and indicates, as a percentage, how much this Bpp is generated from a positive peak value to a negative peak value Vpp of the reproduced output signal, and the baseline noise Bpp is small. Needless to say, there is no reading error and the reliability is excellent. Also, in the in-line type hard disk drive, the thin film MR head is tilted by about ± 10 ° with respect to the disk rotation direction, but the distance between the recording unit and the reproducing unit is small, so that the signal width recorded in the recording unit is limited. On the other hand, the gap of the reproducing section does not protrude.

[0006]

However, in the above-mentioned conventional configuration, the wiggle characteristic when the thin film MR head has a tilt of 0 ° with respect to the rotation direction of the magnetic disk, that is, the thin film MR head is erased / recorded at the same track position. When the reproduction is repeated several tens of times (for example, 30 times), the problem that the wiggle value indicating the variation δ with respect to the average value of the reproduction output signal width value as a percentage is worse than that of the separate type thin film MR head. Had. Further, when the baseline noise is a merge type thin film MR head, it is 3 to
There is a problem that it is about 8%, which is larger than about 2 to 5% of a general separate type thin film MR head.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. The present invention improves the wiggle characteristic and the baseline noise, and provides a high-performance, high-reliability, low-cost, and excellent mass-productivity for obtaining a stable reproduction signal. It is an object of the present invention to provide a thin film MR head.

[0008]

In order to achieve this object, a thin film MR head according to a first aspect of the present invention comprises a substrate, an insulating film laminated on the substrate, and a thin film MR head formed on the substrate. A stacked lower shield layer, a read gap portion having a magnetoresistive element portion stacked on the lower shield layer, an upper shield layer stacked on the read gap portion, and A thin-film magnetoresistive head having an upper core formed by forming a recording gap portion and a protective insulating film stacked on the upper core, wherein the back core portion of the upper core and the upper Cu different from the recording gap between the shield layer and
It has a configuration in which a non-magnetic film made of, claim 2
In the thin film MR head described in the above, the thickness of the nonmagnetic film is
It has a configuration of 0.1 μm to 5.0 μm.

Here, if the thickness of the nonmagnetic film is less than 0.1 μm, the wiggle value is large, and if it exceeds 5.0 μm, the magnetic resistance becomes large, and the recording current needs to be increased. It is not preferable because there is a risk of doing so. Therefore, the wiggle value can be reduced to 1% or less.
5.0 μm is optimal. The non-magnetic film material may be an insulating resist other than Cu and alumina. In particular, in the case of alumina, Cu or insulating resist, it is not necessary to change the conventional manufacturing process, so that the manufacturing can be performed at low cost.

[0010]

With this structure, a non-magnetic film having a predetermined thickness is provided between the back core portion of the upper core and the upper shield layer, and the back core portion and the upper shield layer are magnetically separated from each other so that the back core portion can be reproduced during reproduction. The influence of the change in magnetic flux can be prevented, and a stable reproduction signal can be obtained.

[0011]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a principal part of a thin film MR head according to a first embodiment of the present invention, and FIG. 2 is a sectional view of a principal part of the thin film MR head according to the first embodiment of the present invention. 1 is a substrate, 2 is an insulating film, 3 is a lower shield layer, 4
Is an MR lower gap insulating film, 5 is an MR element portion, and 6 is an MR element.
Upper gap insulating film, 7 is a reproduction gap portion, 8 is an upper shield layer, 9 is a recording gap portion, 10 is an upper core, 1
Reference numeral 1 denotes a protective insulating film, 12 denotes a recording coil, 13 denotes an insulating resist film, and 14 denotes a back core portion, which are the same as those in the conventional example and are denoted by the same reference numerals and description thereof is omitted. 17
Is the back core portion 14 of the upper core 10 and the upper shield layer 8
Is a non-magnetic film made of an alumina film having a thickness of 0.6 μm and formed between them.

The operation of the thin-film MR head configured as described above will be described below. FIG. 3 shows the first embodiment of the present invention.
FIG. 10 is a diagram showing a change in magnetic flux at the time of reproduction of the thin film MR head in the example of FIG. When information is recorded on the magnetic disk medium 15, a recording core portion is formed by the upper core 10 and the upper shield layer 8 as in the conventional example, and the recording gap portion 9 is formed.
Is recorded on the magnetic disk medium 15 via the. At this time,
A non-magnetic film 17 is formed between the back core portion 14 of the upper core 10 and the upper shield layer 8. Since the non-magnetic film 17 is an alumina film having a thickness of 0.6 μm, It is not necessary to supply a particularly large current to the coil 12, and information can be recorded on the magnetic disk medium 15 by passing a magnetic flux 16 necessary for recording even with a normal recording current. The information recorded on the magnetic disk medium 15 is read by the MR element unit 5 in the read gap formed by the lower shield layer 3 and the upper shield layer 8 to change the magnetic flux 16. At this time, the non-magnetic film 17 formed between the back core portion 14 of the upper core 10 and the upper shield layer 8 causes
The back core portion 14 of the upper core 10 and the upper shield layer 8 are magnetically insulated. Therefore, a change in the magnetic flux 16 from the magnetic disk medium 15 at the time of reproduction is suppressed by the nonmagnetic film 17 when passing from the back core portion 14 of the upper core 10 to the upper shield layer 8, and functions as a shield of the MR element portion 5. Become like

A performance comparison test was performed on the thin film MR head according to one embodiment of the present invention, which operates as described above, and a conventional thin film MR head. Hereinafter, the results will be described.

(Experimental Example 1) Using the thin-film MR head according to one embodiment of the present invention, erasure, recording, and reproduction at the same track position of the magnetic disk medium were repeated 30 times, and the amplitude value of the reproduction output signal was measured. Wiggle values were determined. The result is shown in FIG. FIG. 4A is a diagram showing the wiggle characteristics of the thin film MR head in the first experimental example, and FIG. 4B is a diagram showing the wiggle characteristics of a general separate type thin film MR head. (C) is a diagram showing the wiggling characteristics of a conventional merge type thin film MR head.

As is apparent from FIGS. 4A to 4C, the wiggle characteristics of the thin film MR head according to the present embodiment are significantly improved as compared with the conventional merge type thin film MR head. It has been found that the thin film MR head has the same wiggle characteristics as a thin film MR head. Also, when the baseline noise was measured, it was found that it was improved to about 2 to 4%.

As described above, according to the present embodiment, an alumina film, which is a non-magnetic film, is formed between the back core portion 14 of the upper core 10 and the upper shield layer 8 so that the M level during reproduction can be improved.
The R element section 5 can be prevented from being affected by the magnetic flux 16 from the back core section 14 of the upper core 10, and the wiggle characteristic and the baseline noise can be significantly improved. Since the non-magnetic film can be formed simultaneously with the step of forming the recording gap 9, there is no need to change the manufacturing process.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a sectional view of a main part of a thin film MR head according to a second embodiment of the present invention. The difference from the first embodiment is that the nonmagnetic film 17a between the back core portion 14 of the upper core 10 and the upper shield layer 8 is formed of a 3.0 μm thick Cu film.

The operation of the thin film MR head configured as described above will be described below. When information is recorded on the magnetic disk medium in the same manner as in the first embodiment, a current is applied to the recording coil 12 to form a recording core portion with the upper core 10 and the upper shield layer 8 to generate a magnetic flux to generate a magnetic flux. This is performed by magnetizing the magnetic surface of the medium. At this time, a non-magnetic film 17a of a Cu film is formed between the back core portion 14 of the upper core 10 and the upper shield layer 8 forming the lower core, but the thickness is 3.0 μm. The magnetic flux for recording is normally recorded on the magnetic disk medium without being affected. The information recorded on the magnetic disk medium is read out by sensing a change in magnetic flux at the MR element section 5. At this time, the magnetic flux passing from the back core section 14 of the upper core 10 through the upper shield layer 8 is Cu It is suppressed by the film and functions as a shield for the MR element unit 5.

A performance test was performed on the thin-film MR head according to the second embodiment of the present invention which operates as described above.

(Experimental Example 2) Using the thin-film MR head according to the second embodiment of the present invention, erasing, recording, and reproducing at the same track position were repeated 30 times, the amplitude of the reproduced output signal was measured, and the wiggle value was measured. I asked. FIG. 6 shows the result. FIG. 6 is a diagram showing the wiggle characteristics of the thin-film MR head in the second experimental example. As is clear from FIG. 6, the wiggle value was remarkably improved to 1% or less. Also, when the baseline noise was measured,
It was found that it was improved to about 2%.

As described above, according to the present embodiment, a Cu film which is a non-magnetic film is formed between the back core portion 14 of the upper core 10 and the upper shield layer 8, and the back core portion 14 and the upper shield layer 8 are formed. Due to the magnetic separation, the MR element unit 5 causes the magnetic flux 1 from the back core unit 14 of the upper core 10 during reproduction.
6 can be prevented, and wiggle characteristics and baseline noise can be significantly improved. Also,
The Cu film as the non-magnetic film 17a can be formed at the same time when the recording coil 12 as the same Cu film is formed, so that there is no need to change the manufacturing process.

(Experimental Example 3) By forming the non-magnetic film 17 between the back core portion 14 of the upper core 10 and the upper shield layer 8 according to the first and second embodiments, the wiggle value and the baseline noise are reduced. It turned out to be. Therefore, a thin film MR head was prototyped using the thickness of the nonmagnetic film made of an insulating resist as a parameter, and how the wiggle value at each film thickness changed was examined. FIG. 7 shows the result. FIG. 7 is a diagram showing the relationship between the thickness of the thin film MR head, the wiggle value, and the recording current in the third experimental example. As is apparent from FIG. 7, the thickness of the nonmagnetic film is 0.1 μm.
It was found that the wiggle value gradually decreased at m or more, and decreased to about 1% or less at about 2 μm or more. However, when the film thickness is increased to 5 μm or more, the magnetic resistance increases, so that it is necessary to increase the recording current flowing through the recording coil 12 during recording. However, if the recording current is too large, Joule heat causes the MR element 5
Becomes too high, and there is a risk of damaging the MR element portion 5. Therefore, it is not preferable to make the portion too thick. Therefore,
The thickness of the non-magnetic film is in the range of 0.1 μm to 5.0 μm, preferably 2.0 μm to 5.0 μm which can reduce the wiggle value to 1% or less.
0 μm was found to be optimal.

[0023]

As described above, according to the present invention, a non-magnetic film having a predetermined thickness is formed between the back core portion of the upper core and the upper shield layer to magnetically separate the back core portion and the upper shield layer. As a result, the effect of the change in the magnetic flux from the back core portion of the MR element portion can be suppressed, the wiggle value and the baseline noise can be significantly improved, and a stable reproduced signal can be obtained. High performance, high reliability, and low cost Accordingly, it is possible to provide a thin film MR head which is excellent in mass productivity.

[Brief description of the drawings]

FIG. 1 is a plan view of a principal part of a thin film MR head according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the thin-film MR head according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a change in magnetic flux during reproduction of the thin-film MR head according to the first embodiment of the present invention.

4A is a diagram showing the wiggle characteristics of a thin film MR head in the first experimental example. FIG. 4B is a diagram showing the wiggle characteristics of a general separate type thin film MR head. FIG. 4C is a diagram showing a conventional merge type thin film MR head. Showing the wiggle characteristics of the thin film MR head of FIG.

FIG. 5 is a sectional view of a main part of a thin-film MR head according to a second embodiment of the present invention;

FIG. 6 is a diagram showing a wiggle characteristic of a thin-film MR head in a second experimental example.

FIG. 7 is a diagram showing a relationship between the thickness of a thin film MR head, a wiggle value, and a recording current in a third experimental example.

FIG. 8 is a plan view of a main part of a conventional thin film MR head.

FIG. 9 is a sectional view of a main part of a conventional thin film MR head.

FIG. 10 is a diagram showing a change in magnetic flux during reproduction of a conventional thin film MR head.

FIG. 11 shows a reproduction signal of a general thin film MR head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Insulating film 3 Lower shield layer 4 MR lower gap insulating film 5 MR element part 6 MR upper gap insulating film 7 Playback gap part 8 Upper shield layer 9 Recording gap part 10 Upper core 11 Protective insulating film 12 Recording coil DESCRIPTION OF SYMBOLS 13 Insulating resist film 14 Back core part 15 Magnetic disk medium 16 Magnetic flux 17, 17a Non-magnetic film

Claims (2)

(57) [Claims] 1. A reproducing apparatus comprising: a substrate; an insulating film laminated on the substrate; a lower shield layer laminated on the insulating film; and a magnetoresistive element portion laminated on the lower shield layer. A gap portion, an upper shield layer laminated on the reproducing gap portion, an upper core laminated by forming a recording gap portion on the upper shield layer, and a protective insulating layer laminated on the upper core. A thin film magnetoresistive head having a film or the like, wherein the recording gap is provided between a back core portion of the upper core and the upper shield layer.
A thin-film magnetoresistive head comprising a nonmagnetic film made of Cu different from the portion . 2. The method according to claim 1, wherein said nonmagnetic film has a thickness of 0.1 μm to 5.0.
2. The thin film magnetoresistive head according to claim 1 , wherein the thickness is μm.