JPH07153033A - Thin film magnetoresistive head - Google Patents

Abstract

(57) [Abstract] [Purpose] A thin-film magnetoresistive head that improves wiggle characteristics and baseline noise, obtains a stable reproduction signal, has high performance, high reliability, low cost, and excellent mass productivity. The purpose is to provide. [Structure] A substrate 1, an insulating film 2 laminated on the substrate 1, and a lower shield layer 3 laminated on the insulating film 2.
A reproducing gap portion 7 having an MR element portion 5 laminated on the lower shield layer 3, an upper shield layer 8 laminated on the reproducing gap portion 7, and recording on the upper shield layer 8. A thin-film MR head having an upper core 10 laminated with a gap portion 9 formed thereon, a protective insulating film 11 laminated on the upper core 10, and the like, wherein a back core portion 14 of the upper core 10 and the back core portion 14 are formed. Upper shield layer 8
And a non-magnetic film 17 between the two.

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 in a magnetic memory device such as a computer.

[0002]

2. Description of the Related Art In recent years, hard disk drives, which are magnetic storage devices, are required to be smaller and have larger capacities year by year, track widths are becoming narrower, and recording density tends to be higher. Under such circumstances, a thin film MR head equipped with a magnetoresistive effect element (hereinafter abbreviated as MR element) has been developed in order to achieve ultra high density. There are two types of thin-film MR heads: a separate type in which the recording core part and the shield part of the reproducing part are separated separately, and a merge type in which the lower core of the recording core part also serves as the upper shield of the reproducing part. The merge type thin film MR head 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 inline type hard disk drive device. Further, since the number of steps is small in the manufacturing process of the thin film MR head, a merge type thin film MR head (hereinafter, simply referred to as a thin film MR head) is used recently.

A conventional thin film MR head will be described below. FIG. 8 is a plan view of relevant parts of a conventional thin film MR head, and FIG. 9 is a sectional view of relevant parts of the conventional thin film MR head.
Reference numeral 1 is a substrate that serves as 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 laminated on the lower shield layer 3, and 5 is FeNi laminated on the MR lower gap insulating film 4 for detecting magnetism. M consisting of sputtered film
R element portion, 6 is an MR upper gap insulating film made of an alumina film laminated on the MR element portion 5, 7 is an MR lower gap insulating film 4, MR element portion 5, MR upper gap insulating film 6
A reproducing gap portion consisting of 8; an upper shield layer 8 which is a FeNi plating film laminated on the reproducing gap portion 7 and also serves as a lower core; 9 a recording gap portion consisting of an alumina layer;
10 is an upper core for recording made of a FeNi plated film, 1
Reference numeral 1 is a protective insulating film made of an alumina film laminated on the upper core 10. In FIG. 9, 12 is a recording coil of a Cu-plated film laminated between the upper shield layer 8 and the upper core 10, 13 is an insulating resist film, and 14 is an upper core 10 in direct contact with the upper shield layer 8. It is the back core part.

Here, the back core portion 14 of the upper core 10
Is in direct contact with the upper shield layer 8 and forms a recording core portion during recording to facilitate the passage of magnetic flux. Further, since the lower shield layer 3 and the upper shield layer 8 are located substantially parallel to each other, and this space serves as a read gap during reproduction, the dimensional accuracy of this space is an important factor in determining the performance of the thin film MR head. Is.

The operation of the conventional thin film MR head constructed as described above will be described below. FIG. 10 is a diagram showing changes in magnetic flux during reproduction of a conventional thin film MR head. Reference numeral 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 portion and a reproducing portion as shown in FIG. 10, but the upper shield layer 8 of the reproducing portion plays a role of a lower core of the recording portion at the time of recording, thereby achieving an ultra high density. Various magnetic recording and reproduction are possible.
When recording information on the magnetic disk medium 15, an electric current is passed through the recording coil 12 so that the upper core 10 and the upper shield layer 8 form a recording core portion, and the magnetic flux 16 causes a magnetic surface of the magnetic disk medium 15. Information is recorded by magnetizing. On the other hand, when reproducing the information recorded on the magnetic disk medium 15, a sense current is supplied to the MR element portion 5 to generate a magnetic flux 16 of the information recorded on the magnetic disk medium 15.
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
It is a figure showing a reproduced signal of the R head. In FIG. 11, Bpp is called baseline noise, and the percentage of how much Bpp is generated from the positive peak value to the negative peak value Vpp of the reproduction output signal is displayed as a percentage, and the baseline noise Bpp is small. It goes without saying that it is more reliable and has no read errors. Further, in the in-line type hard disk drive device, the thin film MR head is tilted about ± 10 ° with respect to the disk rotation direction, but the distance between the recording part and the reproducing part is small, so that the signal width recorded in the recording part is small. On the other hand, the gap in the playback section does not overflow.

[0006]

However, in the above conventional structure, the wiggle characteristic when the thin film MR head has an inclination of 0 ° with respect to the magnetic disk rotation direction, that is, the thin film MR head is erased / recorded at the same track position. When the reproduction is repeated tens of times (for example, 30 times), there is a problem that the wiggle value in which the variation amount δ of the reproduction output signal width value with respect to the average value is displayed as a percentage is worse than that of the separate type thin film MR head. Had. Also, in the case of a merge type thin film MR head, the baseline noise 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.

The present invention solves the above-mentioned problems of the prior art by improving wiggle characteristics and baseline noise, obtaining a stable reproduction signal, high performance and high reliability, low cost and excellent mass productivity. Another object of the present invention is 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 has a substrate, an insulating film laminated on the substrate, and an insulating film on the insulating film. A reproducing lower gap layer having a laminated lower shield layer, an MR element portion laminated on the lower shield layer, an upper shield layer laminated on the reproducing gap portion, and recording on the upper shield layer. What is claimed is: 1. A thin-film MR head comprising: an upper core laminated with a gap portion formed thereon; and a protective insulating film laminated on the upper core, the thin-film MR head being provided between a back core portion of the upper core and the upper shield layer. The thin-film MR head according to claim 2 is characterized in that the material of the non-magnetic film is alumina, Cu, or an insulating resist.
The thin-film MR head according to claim 3 has the structure according to claim 1 or 2, wherein the thickness of the non-magnetic film is 0.1 μm to 5.0 μm, preferably 2.0 μm.
It has a structure in the range of m to 5.0 μm.

Here, if the thickness of the non-magnetic 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 it is necessary to increase the recording current, and the MR element portion is damaged. It is not preferable because there is a risk of Therefore, the wiggle value can be reduced to 1% or less 2.0 μm
The optimum value is ˜5.0 μm. The non-magnetic film material may be an insulating resist other than Cu and alumina. In particular, in the case of alumina, Cu, or an insulating resist, there is no need to change the conventional manufacturing process, so that it can be manufactured 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. It is possible to prevent the influence of the change in magnetic flux and obtain a stable reproduction signal.

[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 relevant parts of a thin film MR head according to a first embodiment of the present invention, and FIG. 2 is a sectional view of relevant parts of a 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 part, and 6 is an MR
Upper gap insulating film, 7 a reproducing gap portion, 8 an upper shield layer, 9 a recording gap portion, 10 an upper core, 1
Reference numeral 1 is a protective insulating film, 12 is a recording coil, 13 is an insulating resist film, and 14 is 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 will be omitted. 17
Is the back core portion 14 of the upper core 10 and the upper shield layer 8
It is a non-magnetic film made of an alumina film having a thickness of 0.6 μm formed between and.

The operation of the thin film MR head having the above structure will be described below. FIG. 3 shows the first of the present invention.
FIG. 6 is a diagram showing changes in magnetic flux during reproduction of the thin film MR head in the example of FIG. When information is recorded on the magnetic disk medium 15, the 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.
It is recorded on the magnetic disk medium 15 via the. 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, but since the non-magnetic film 17 is an alumina film having a thickness of 0.6 μm, it is suitable for recording. It is not necessary to pass a particularly large current through the coil 12, and it is possible to record information on the magnetic disk medium 15 by passing the magnetic flux 16 required for recording even with a normal recording current. The information recorded on the magnetic disk medium 15 is read by the MR element portion 5 in the read gap formed by the lower shield layer 3 and the upper shield layer 8 as the change of the magnetic flux 16. At this time, due to the non-magnetic film 17 formed between the back core portion 14 of the upper core 10 and the upper shield layer 8,
The back core portion 14 of the upper core 10 and the upper shield layer 8 are magnetically insulated. Therefore, during reproduction, the change in the magnetic flux 16 from the magnetic disk medium 15 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. Like

Performance comparison tests were carried out on the thin film MR head of the embodiment of the present invention which operates as described above and the conventional thin film MR head. The results will be described below.

(Experimental Example 1) Using the thin film MR head in one embodiment of the present invention, erasing, recording and reproducing were repeated 30 times at the same track position on the magnetic disk medium, and the amplitude value of the reproduction output signal was measured. The wiggle value was calculated. The result is shown in FIG. FIG. 4A is a diagram showing a wiggle characteristic of the thin film MR head in the first experimental example, and FIG. 4B is a diagram showing a wiggle characteristic of a general separate type thin film MR head. FIG. 3C is a diagram showing the wiggle characteristics of a conventional merge type thin film MR head.

As is apparent from FIGS. 4 (a) to 4 (c), the wiggle characteristics of the thin film MR head in this embodiment are remarkably improved as compared with the conventional merge type thin film MR head, and are generally separated. It was found that the thin film MR head of the type has the same wiggle characteristics. Also, when the baseline noise was measured, it was found that it was improved to about 2 to 4%.

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

(Second Embodiment) A second embodiment of the present invention will be described below 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 Example 1 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 Cu film having a film thickness of 3.0 μm.

The operation of the thin film MR head having the above structure will be described below. When information is recorded on the magnetic disk medium as in the first embodiment, a current is passed through 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 disk. This is done by magnetizing the magnetic surface of the medium. At this time, a non-magnetic film 17a made 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 film thickness is 3.0 μm. The magnetic flux for recording is not affected and is normally recorded on the magnetic disk medium. Further, the information recorded on the magnetic disk medium is read by sensing the change of the magnetic flux in the MR element portion 5, but at this time, the magnetic flux passing from the back core portion 14 of the upper core 10 to 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 conducted 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 / reproducing is repeated 30 times at the same track position, the amplitude value of the reproducing output signal is measured, and the wiggle value is measured. I asked. The result is shown in FIG. 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, it was found that the wiggle value was significantly improved to 1% or less. When the baseline noise is measured, it is 0
It was found to have been improved to about 2%.

As described above, according to this 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 to form the back core portion 14 and the upper shield layer 8. Due to the magnetic separation, the MR element portion 5 causes the magnetic flux 1 from the back core portion 14 of the upper core 10 during reproduction.
6 can be prevented and the wiggle characteristics and the baseline noise can be remarkably improved. Also,
Since the Cu film that is the non-magnetic film 17a can be formed at the same time when the recording coil 12 that is the same Cu film is formed, it is not necessary 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. Then, a thin-film MR head was prototyped with the film thickness of the non-magnetic film made of an insulating resist as a parameter, and it was investigated how the wiggle value at each film thickness changes. The result is shown in FIG. 7. FIG. 7 is a diagram showing the relationship among the film thickness, the wiggle value, and the recording current of the thin film MR head in the third experimental example. As is clear from FIG. 7, the thickness of the nonmagnetic film is 0.1 μm.
It was found that the wiggle value gradually decreased when m or more, and the wiggle value decreased to approximately 1% or less when it became about 2 μm or more. However, if the film thickness is increased to 5 μm or more, the magnetic resistance increases, so that it is necessary to increase the recording current supplied to the recording coil 12 during recording. However, if the recording current is increased too much, the MR element portion 5 will be heated by Joule heat.
Since there is a risk that the temperature in the vicinity of will become high and the MR element part 5 will be damaged, it is not preferable to make it 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. 5 μm, which allows the wiggle value to be 1% or less.
It was found that 0 μm was optimal.

[0023]

As described above, according to the present invention, a nonmagnetic 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 MR element part can suppress the influence of the change of the magnetic flux from the back core part, can significantly improve the wiggle value and the baseline noise, and can obtain a stable reproduction signal. High performance, high reliability, and low cost. Thus, it is possible to realize the provision of a thin film MR head excellent in mass productivity.

[Brief description of drawings]

FIG. 1 is a plan view of an essential 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 a thin film MR head according to a 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.

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

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 wiggle characteristics of a thin film MR head in a second experimental example.

FIG. 7 is a diagram showing the relationship between the film thickness of the thin film MR head and the wiggle value and the recording current in the 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 is a diagram showing a reproduction signal of a general thin film MR head.

[Explanation 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 reproducing gap part 8 upper shield layer 9 recording gap part 10 upper core 11 protective insulating film 12 recording coil 13 insulating resist film 14 back core part 15 magnetic disk medium 16 magnetic flux 17, 17a non-magnetic film

Claims (3)

[Claims] 1. A reproducing device having a substrate, an insulating film laminated on the substrate, a lower shield layer laminated on the insulating film, and a magnetoresistive effect element portion laminated on the lower shield layer. A gap part, an upper shield layer laminated on the reproducing gap part, an upper core laminated with a recording gap part formed on the upper shield layer, and a protective insulation laminated on the upper core. A thin-film magnetoresistive head having a film or the like, comprising a nonmagnetic film between a back core portion of the upper core and the upper shield layer. 2. The thin-film magnetoresistive head according to claim 1, wherein the material of the non-magnetic film is one of alumina, Cu, and an insulating resist. 3. The film thickness of the non-magnetic film is 0.1 μm to 5.0.
3. The thin-film magnetoresistive head according to claim 1, wherein the thin-film magnetoresistive effect head is .mu.m.