JPH08147634A - Magnetoresistance head and magnetic disk apparatus - Google Patents

Abstract

PURPOSE: To obtain a magnetoresistance head which can perform high line density recording by a method wherein a shield layer in which a difference in worked difference is small and whose resistance is high can be manufactured. CONSTITUTION: A thin film, as a lower-part shield layer 111, in which 5mol% of zirconium oxide has been added to an Ni81 Fe15 thin film by a sputtering method is patterned to be a prescribed shape by an ion milling operation on a nonmagnetic substrate 10 on which an insulating layer such as alumina or the like has been formed to be a thin film and to which a precision polishing operation has been executed. A lower- part gap layer 121 is formed on it. An Ni-Fe-Nb-Co-based alloy as a soft magnetic thin film 13 which is used to apply a lateral-direction bias magnetic field, Ta as a nonmagnetic conductive thin film 14, Permalloy as a magnetoresistance-effect film and an FeMn thin film 16 which restrains the Barkhausen noise are formed and patterned. An electrode 17 is formed to be a prescribed shape, and an upper-part gap layer 122 is formed and patterned. Then, an upper-part shield layer 121 is formed and patterned, and a protective film 18 is formed. In order to magnetize the FeMn thin film 16, the thin film is heat-treated at 275 deg.C for 30 minutes while a DC magnetic field at 3kOe is being applied to a read-track-width-direction, and the substrate is then cut so as to be worked to be a slider.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head and a magnetic disk device used for reproducing information recorded on a magnetic medium.

[0002]

2. Description of the Related Art In order to cope with recent miniaturization and high recording density of magnetic disk devices, there has been proposed a recording / reproducing separated type head which has a recording function and a reproducing function separately and uses them with optimum characteristics. In general, the recording / reproducing separated type head uses an induction type thin film head as a recording head, and a magnetoresistive head capable of obtaining a large reproducing output even if the relative speed between the magnetic head and the magnetic recording medium is small. Used.

In order to realize high resolution in the magnetoresistive head, a pair of shield layers are arranged above and below the magnetoresistive film via a gap layer to remove magnetic fields other than the signal magnetic field to be reproduced. Be seen. As the material of this shield layer, a soft magnetic thin film is used as described in JP-A-2-116009.

[0004]

However, when polishing the air bearing surface (the surface facing the magnetic recording medium) of the thin film magnetic head, a shield is provided between the nonmagnetic substrate, the oxide film as the insulating layer, and the shield layer. Due to the high etching rate of the layer, FIG.
As described above, there is a problem that a step is formed between the lower end of the shield layer and the surface of the non-magnetic substrate. Such a step is called a processing step.

As a means for improving the sensitivity of the magnetoresistive head, the magnetoresistive film is thinned.

The giant magnetoresistive effect generated in a laminated film of thin films having a thickness of several nm is used.

In any case, it is necessary to exhibit good electromagnetic characteristics and thermal stability even when a thin film is formed. For that purpose, it is desirable that the underlying shield layer has small irregularities.

An object of the present invention is to use a shield layer having a small processing step and small unevenness on the film surface.
It is an object of the present invention to provide a magnetoresistive head having high sensitivity capable of coping with a narrow gap and a magnetic disk device capable of high recording density.

[0009]

At least one of a lower shield layer and an upper shield layer is made of Ni, Fe, Co.
One or more of zirconium oxide, aluminum oxide,
Consists of a compound-containing soft magnetic thin film containing one or more selected from hafnium oxide, titanium oxide, beryllium oxide, magnesium oxide, zirconium nitride, aluminum nitride, hafnium nitride, titanium nitride, beryllium nitride, magnesium nitride, and silicon nitride. To do. At this time,
The compound-containing soft magnetic thin film contains 2 to 18 m of the compound.
A thin film containing ol% is used.

Further, the shield layer may be composed not of a single layer film but of a multilayer film containing a compound-containing soft magnetic thin film. The multilayer film including a plurality of compound-containing soft magnetic thin films having different compositions can be used for both the upper and lower shield layers. A compound-containing soft magnetic thin film and a multilayer film including one or more soft magnetic thin films can be used for either shield layer, but there is a more desirable configuration depending on the combination of materials. For example, when a compound-containing soft magnetic thin film and a permalloy or nitrogen-added permalloy multilayer film are used for the lower shield layer, the uppermost layer of the lower shield layer is preferably the compound-containing soft magnetic thin film. When a multilayer film including a compound-containing soft magnetic thin film and an amorphous soft magnetic thin film is used for the lower shield layer, it is desirable that the uppermost layer of the lower shield layer be the amorphous soft magnetic thin film. When a multilayer film of a compound-containing soft magnetic thin film and an amorphous soft magnetic thin film is used for the upper shield layer, it is desirable that the lowermost layer of the upper shield layer be the compound-containing soft magnetic thin film.

By mounting this magnetoresistive head on a magnetic disk device, the linear recording density is 170 kBP.
I or more or the areal recording density can be set to 1.5 Gb / in ² or more.

[0012]

The steps of processing the shield layer can be reduced by using a material having good corrosion resistance for the shield layer. If one or more oxides or nitrides are mixed in a soft magnetic thin film containing one or more of magnetic metals Ni, Fe and Co so as to exist as a compound without being decomposed in the thin film, the magnetic properties are greatly impaired. In addition, a compound-containing soft magnetic thin film having high electric resistance and good corrosion resistance can be obtained. In such a thin film, the compound is mixed into the metal thin film, so that the crystal grains become small, so that the unevenness on the surface of the thin film can be made small. Oxides and nitrides that produce such effects are compounds having a strong bond, and oxides are zirconium oxide, aluminum oxide, hafnium oxide, titanium oxide, beryllium oxide, and magnesium oxide, and nitrides are zirconium nitride and aluminum nitride. , Hafnium nitride, titanium nitride, beryllium nitride, magnesium nitride, and silicon nitride. When the content of these compounds is small, the corrosion resistance is not improved, and when the content is too large, the magnetic permeability required for the shield layer cannot be obtained. Therefore, a thin film having a compound content of 2 to 18 mol% can be applied.

The shield layer is required to have a magnetic permeability of several hundreds or more. When the linear recording density increases and the thickness of the gap layer becomes thin, a gap layer having excellent insulation properties is produced. Since it becomes difficult to do so, it is necessary that the electric resistance of the surface of the shield layer in contact with the gap layer is large. In this case, in addition to the method of using a single layer film of a compound-containing soft magnetic thin film having high electric resistance and magnetic permeability, at least two layers of compound-containing soft magnetic thin films having different resistances are laminated, and the thin film having the highest resistance is the gap layer side. There is a way to place it. On the other hand, when priority is given to resolution, a structure in which a compound-containing soft magnetic thin film having a large magnetic permeability is arranged on the gap layer side is desirable. As described above, the use of the multilayer film can easily serve different purposes.

In order to improve the corrosion resistance without impairing the magnetic properties of the shield layer, the shield layer may be composed of a compound-containing soft magnetic thin film and a multilayer film containing one or more soft magnetic thin films. At this time, in order to reduce the unevenness of the uppermost surface of the lower shield layer, it is necessary to use a thin film having a small grain size as the uppermost layer of the lower shield layer. In combination with permalloy or permalloy containing nitrogen, the compound containing When the soft magnetic thin film is combined with the amorphous soft magnetic thin film, the amorphous soft magnetic thin film is the uppermost layer.

Amorphous soft magnetic thin films have poor adhesion and require an adhesive layer. When an amorphous soft magnetic thin film is applied to the upper shield layer, the gap layer becomes thicker in the non-magnetic thin film adhesion layer, and therefore the magnetic thin film must be used as the adhesion layer. At this time, in view of throughput, it is desirable to use a material that can obtain good magnetic characteristics without heating the substrate. From this point, the compound-containing soft magnetic thin film is preferable. As described above, by forming the compound-containing soft magnetic thin film as the lowermost layer, the amorphous soft magnetic thin film can be used as the upper shield layer.

When the compound-containing soft magnetic thin film is used for the shield layer, a shield layer having a flat surface and high resistance can be obtained without largely deteriorating the magnetic characteristics, so that the gap layer can be made thin and a high linear recording density can be obtained. It becomes possible to respond. Further, in the case of the recording / reproducing separated type head, when the upper shield layer also serves as the lower magnetic pole of the recording head, by using a material having a high saturation magnetic flux density and a high magnetic permeability (for example, an amorphous magnetic material) in the upper shield layer, The top shield layer can be thin. As a result, the positional deviation between the recording track and the reproducing track and the recording track width can be reduced, so that the track density can be increased, and as a result, the areal recording density is improved.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Example 1) First, the characteristics of a thin film containing a compound will be described. The thin film was prepared by mixing powders of various compounds and powders of alloys containing one or more of Ni, Fe, and Co and solidifying them, and using an RF conventional sputtering device, Ar gas pressure 2m.
Made with Torr. Here, in order to induce magnetic anisotropy,
Film formation was performed while applying a magnetic field of about 40 Oe. Corrosion rate, resistivity, frequency obtained from polarization characteristics of alkaline liquid with pH of about 10 for thin film with thickness of about 1 μm
The relative permeability and average surface roughness at 1MHz were evaluated. Table 1
Is Ni ₈₁ Fe ₁₉ , zirconium oxide, aluminum oxide, hafnium oxide, titanium oxide, beryllium oxide,
It is the evaluation result of the thin film to which about 5% of magnesium oxide, zirconium nitride, aluminum nitride, hafnium nitride, titanium nitride, beryllium nitride, magnesium nitride, and silicon nitride was added.

[0019]

[Table 1]

For comparison, a thin film containing about 5% silicon oxide and a Ni ₈₁ Fe ₁₉ thin film containing no compound were also evaluated. The corrosion rate of the thin film added with the above compounds except silicon oxide is lower than that of the Ni ₈₁ Fe ₁₉ thin film, but the thin film added with silicon oxide is
It is larger than the Ni ₈₁ Fe ₁₉ thin film. It is considered that this is because in the thin film to which the compound other than silicon oxide is added, the compound exists in a state of being bonded without being decomposed, and in the case of silicon oxide, it is partially decomposed in the film. Although not shown in Table 1, a thin film added with a compound other than silicon oxide even in an acidic solution is Ni ₈₁ Fe ₁₉
The corrosion resistance is improved as compared with the thin film, and the corrosion rate is about 0.008 nm / h smaller than the value shown in Table 1 because the compound stable to acid is added. The resistivity shows a value of 70 μΩ · cm or more for the thin film to which a compound other than silicon oxide is added, but is 30 μΩ · cm or less for the Ni ₈₁ Fe ₁₉ thin film and the thin film to which silicon oxide is added. Regarding the relative magnetic permeability, it was 900 when the compound was added.
Although it decreases to some extent, it is a sufficient value for the shield layer. The average surface roughness is 12.6 n for Ni ₈₁ Fe ₁₉ thin film.
m, but at most 8. by adding the compound.
It is as small as 8 nm. Thus, it can be seen that the addition of the compound improves the corrosion resistance, increases the specific resistance, and reduces the surface irregularities of the thin film, but decreases the magnetic permeability.

Titanium oxide having a small relative magnetic permeability value will be described in Table 1 as an example. Table 2 shows the evaluation results of the thin film obtained by adding titanium oxide to the Ni ₈₁ Fe ₁₉ thin film. The corrosion rate becomes smaller than that in the Ni ₈₁ Fe ₁₉ thin film when titanium oxide is added in an amount of 2 mol% or more, and when the titanium oxide content is further increased, it becomes as low as 0.010 nm / h at 12 mol%. Although the corrosion rate increases at 12 mol% or more, it is smaller than that of the Ni ₈₁ Fe ₁₉ thin film even when 20 mol% is added. The reason why the corrosion rate changes in this way seems to be that the corrosion resistance gradually improves by adding titanium oxide, but since the test solution is alkaline, the titanium oxide begins to dissolve from the content above a certain value. Be done. In the acidic test solution, the corrosion rate monotonically decreases as the titanium oxide content increases. The specific resistance is
When the titanium oxide content increases, it increases monotonically, and the average surface roughness and relative permeability decrease. Regarding the relative magnetic permeability, it is considered that a value of preferably 500 or more, at least about 400, is necessary, and the content of titanium oxide must be 18 mol% or less. The content of titanium oxide is determined to be 2 mol% or more and 18 mol% or less depending on the corrosion rate and the relative magnetic permeability. Although titanium oxide having a small relative magnetic permeability has been described as an example here, similar results are obtained for compounds other than silicon oxide shown in Table 1.

[0022]

[Table 2]

Table 3 shows the evaluation results when zirconium oxide was added to various metal thin films.

[0024]

[Table 3]

For comparison, the characteristics when zirconium oxide is not added are also shown. Since iron and iron-cobalt to which zirconium oxide was not added did not induce a clear magnetic anisotropy, the relative magnetic permeability was about 700, but when zirconium oxide was added, magnetic anisotropy was induced and the relative magnetic permeability was increased. Has improved to about 1600. With regard to nickel-iron-cobalt, the addition of zirconium oxide improves the soft magnetic characteristics, and therefore the relative permeability is less deteriorated than the Ni ₈₁ Fe ₁₉ thin film in Table 1. Regarding other characteristics, as in the case of the Ni ₈₁ Fe ₁₉ thin film, when zirconium oxide is added, the corrosion rate and the average surface roughness are reduced and the specific resistance is increased.

FIG. 1 is a perspective view of a magnetoresistive head according to an embodiment of the present invention in which a compound-containing soft magnetic thin film is used as a shield layer. A lower shield layer 1 is formed on a non-magnetic substrate 10 on which an insulating layer such as alumina is formed into a thin film and precision polished.
As No. 11, a thin film in which 5 mol% of zirconium oxide was added to a Ni ₈₁ Fe ₁₉ thin film was formed by a sputtering method, patterned into a predetermined shape by ion milling, and a lower gap layer 121 was formed thereon. Ni-Fe which is a soft magnetic thin film 13 for applying a lateral bias magnetic field
-Nb-Co alloy and nonmagnetic conductive thin film Ta, magnetoresistive film 15 permalloy, and antiferromagnetic film for suppressing Barkhausen noise generated from magnetoresistive film 15. The FeMn thin film 16 was formed by sputtering, and a predetermined pattern was formed by ion milling. In the FeMn thin film 16, the read track portion was removed by ion milling. Electrode film 17
After being formed into a predetermined shape, the upper gap layer 122 was formed and patterned. Top shield layer 1 consisting of a thin film of Ni ₈₁ Fe ₁₉ thin film with 5 mol% zirconium oxide added
12 was formed into a film and patterned to form a protective film 18. F
In order to magnetize the eMn thin film 16, heat treatment was performed at 275 ° C. for 30 minutes while applying a DC magnetic field of 3 kOe in the reading track width direction, and then the substrate was cut and processed into a slider.

In this embodiment, Ni is used as the soft magnetic thin film 13.
-Fe-Nb-Co alloy, Ta as the non-magnetic conductive thin film 14, Permalloy as the magnetoresistive film 15,
Although the FeMn thin film is used as the magnetic domain control film 16, it is not particularly limited to these thin films.

The processing step of the shield layer of the magnetoresistive head manufactured as described above was 5 nm. For comparison, a magnetoresistive head using a Ni—Fe alloy in the shield layer was manufactured, and the processing step of the shield layer was measured to be 8 nm. In addition, a magnetoresistive head having a different distance between the lower shield layer and the upper shield layer was manufactured,
The insulating properties of the lower gap layer and the upper gap layer were investigated. The minimum distance between the lower shield layer and the upper shield layer that allows the sense current to flow through the magnetoresistive film without leaking to the shield layer is 0.3 when the Ni--Fe alloy is used.
While it was 0 μm, the magnetoresistive head of this example had a thickness of 0.25 μm. Similar results were obtained when a thin film containing a compound other than silicon oxide shown in Table 1 was used as the shield layer. As described above, by using the compound-containing soft magnetic thin film for the shield layer, a narrow gap can be obtained, so that it can be applied to a magnetic disk device having a high linear recording density.

(Embodiment 2) A perspective view of a magnetoresistive head according to another embodiment of the present invention is shown in FIG. On the non-magnetic substrate 10, a Ni ₈₁ Fe ₁₉ layer is formed as the lower shield layer 21.
Thin film 211 in which 5 mol% zirconium oxide is added to the thin film
Then, a laminated film of a thin film 212 added with 12 mol% was formed and patterned into a predetermined shape by ion milling, and the lower gap layer 121 was formed thereon. Soft magnetic thin film 13
A non-magnetic conductive thin film 14, a magnetoresistive film 15,
Antiferromagnetic film 16, electrode film 17, upper gap layer 12
2 was manufactured in the same manner as in Example 1. As the upper shield layer 22, 12 mol of zirconium oxide is applied to a Ni ₈₁ Fe ₁₉ thin film.
After forming and patterning a laminated film of the added thin film 221 and the CoTaZr amorphous thin film 222, the protective film 18 was formed. After the antiferromagnetic film 16 was magnetized in the same manner as in Example 1, the substrate was cut and processed into a slider.

The processing step of the magnetoresistive head of this example was 3 nm. The minimum distance between the lower shield layer and the upper shield layer that can maintain insulation can be narrowed to 0.20 μm by disposing a thin film having high resistance on the side close to the gap layer. Moreover, since the CoTaZr amorphous thin film having a saturation magnetic flux density of about 1.3 T is used for the upper shield layer, when the recording / reproducing separated type head in which the upper shield layer also serves as the lower magnetic pole of the write head is manufactured. Can be expected to have excellent recording characteristics. Further, when the recording / reproducing separated type head is positioned by the rotary actuator, the upper shield layer can be thinned and the distance between the reproducing head and the recording head can be shortened. As a result, the positional deviation between the recording track and the reproducing track can be reduced and the width of the recording track can be narrowed, so that the track density can be improved and a higher recording density can be achieved. In the lower shield layer, the side close to the lower gap layer is a high resistance compound-containing soft magnetic thin film, and in the upper shield layer the side close to the upper gap layer is a high resistance compound-containing soft magnetic thin film,
If the material near the recording head has a high saturation magnetic flux density and a high magnetic permeability, similar performance improvement can be expected.

[0031]

According to the present invention, since a shield layer having a small processing step and a high resistance can be produced, the flying height is substantially low and the gap between the shield layers can be narrowed, so that a high linear recording density can be dealt with. A magnetoresistive head can be obtained. Further, since the unevenness of the film surface can be reduced, good characteristics can be obtained even with a thin magnetic film or a laminated film, so that a highly sensitive magnetoresistive head can be obtained. Therefore, by mounting the magnetoresistive head of the present invention, a magnetic disk device having a high areal recording density can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetoresistive head according to an embodiment of the present invention.

FIG. 2 is a perspective view of a magnetoresistive head according to a second embodiment of the present invention.

FIG. 3 is an explanatory view of a processing step.

[Explanation of symbols]

10 ... Nonmagnetic substrate, 13 ... Soft magnetic thin film, 14 ... Nonmagnetic conductive thin film, 15 ... Magnetoresistive effect film, 16 ... Antiferromagnetic film,
17 ... Electrode film, 18 ... Protective film, 111 ... Lower shield layer, 112 Upper shield layer, 121 ... Lower gap layer,
122 ... upper gap layer.

Claims (8)

[Claims] 1. A lower magnetic shield layer, a lower gap layer, a magnetoresistive effect film for detecting a signal magnetic field from a magnetic recording medium, and a bias magnetic field applied to the magnetoresistive effect film for linearizing a reproduction signal. Means, a magnetic domain control layer for suppressing Barkhausen noise, a conductor part for supplying a detection current to the magnetoresistive film and reading an output voltage at the same time, an upper gap layer, and an upper magnetic shield layer. In the effect type head, the lower magnetic shield layer and / or the upper magnetic shield layer are made of Ni, F
One or more of e and Co, and selected from zirconium oxide, aluminum oxide, hafnium oxide, titanium oxide, beryllium oxide, magnesium oxide, zirconium nitride, aluminum nitride, hafnium nitride, titanium nitride, beryllium nitride, magnesium nitride, and silicon nitride. A magnetoresistive head, comprising a compound-containing soft magnetic thin film of one or more of the above. 2. The compound according to claim 1, wherein the compound is 2 to 18 mo.
l% included magnetoresistive head. 3. The magnetoresistive head according to claim 2, wherein the lower shield layer or the upper shield layer is a multilayer film including a plurality of thin films having different compositions of the compound-containing soft magnetic thin film. 4. The magnetoresistive head according to claim 2, wherein the lower shield layer or the upper shield layer is a multilayer film including at least one or more of the compound-containing soft magnetic thin film and the metal magnetic thin film. 5. The lower shield layer according to claim 4, which is a multilayer film of the compound-containing soft magnetic thin film and permalloy or nitrogen-added permalloy, and the uppermost layer of the lower shield layer is the compound-containing soft magnetic film. A magnetoresistive head that is a thin film. 6. The lower shield layer according to claim 4, which is a multilayer film of the compound-containing soft magnetic thin film and the amorphous soft magnetic thin film, and the uppermost layer of the lower shield layer is the amorphous soft magnetic thin film. A magnetoresistive head. 7. The upper shield layer according to claim 4, which is a multilayer film of the compound-containing soft magnetic thin film and the amorphous soft magnetic thin film, and the lowermost layer of the upper shield layer is the compound-containing soft magnetic thin film. Magnetoresistive head. 8. A magnetic recording medium for storing information, a drive unit for rotating the magnetic recording medium, and the magnetoresistive head according to claim 1, 2, 3, 4, 5, 6 or 7. A magnetic disk device comprising an actuator for moving a magnetic head to a predetermined position and having a linear recording density of 170 kBPI or more or an areal recording density of 1.5 Gb / in ² or more.