JPH07118060B2 - Magnetoresistive head - Google Patents

Description

The present invention relates to a ferromagnetic magnetoresistive effect element (hereinafter abbreviated as MR element) for reading out magnetic information written in a magnetic storage medium by utilizing a magnetoresistive effect. The present invention relates to a magnetoresistive effect head (hereinafter abbreviated as MR head).

(Prior Art) As is well known, when an MR element is used as a highly efficient read-only magnetic head that exhibits a linear response to magnetic information written in a magnetic storage medium, a sense applied to the MR element is sensed. Bias means for setting an angle θ (hereinafter referred to as a bias angle) formed by the current I and the magnetization M of the MR element to a predetermined value (preferably 45 degrees) must be provided.

Various methods have been disclosed as the above-mentioned bias means. Among them, in the MR head disclosed in Japanese Utility Model Laid-Open No. 60-159518 or Japanese Patent Laid-Open No. 63-237204,
Non-magnetic conductor layer and amorphous soft magnetic layer (eg Co
It has been shown that a structure in which a ZrMo film) is sequentially laminated provides a good bias angle θ, and an MR head with excellent linear response can be realized. That is, as shown in FIG.
An MR element 1 (for example, a film thickness of 200 to 5 having a thickness of 200 to 5) formed of a ferromagnetic thin film is formed on an insulating substrate (not shown) having a smooth surface made of glass, ferrite or the like by a sputtering method or an evaporation method.
00Å NiFe alloy) is formed, and Ti, Mo,
Disclosed is an MR head having a structure in which a non-magnetic conductor layer 2 such as Cr is formed by the same method, and an amorphous soft magnetic layer 5 is formed on the non-magnetic conductor layer 2 by the same method. . Here, 6 is a terminal for energizing the laminated body of the MR element 1, the non-magnetic conductor layer 2 and the amorphous magnetic layer 5.

In such an MR head, the sense current I supplied from the terminal 6 is shunted not only to the MR head 1 but also to the non-magnetic conductor layer 2 and the amorphous magnetic layer 5. Therefore, in such a structure, the magnetic field in the direction perpendicular to the direction of the sense current I is passed by the sense current I shunted to the MR element 1 and the nonmagnetic conductor layer 2 through the plane of the amorphous soft magnetic layer 5. Occurs, and the magnetization direction of the amorphous soft magnetic layer 5 is rotated by this magnetic field. Therefore, the magnetization in the amorphous soft magnetic layer 5 generates a magnetic field in the direction opposite to the direction of the magnetization around the amorphous soft magnetic layer 5, and a part of the magnetic field is applied to the MR element 1. . on the other hand,
The sense current I shunted to the amorphous soft magnetic layer 5 and the non-magnetic conductor layer 2 causes a magnetic field in the direction perpendicular to the sense current I passing through the plane of the MR element 1. The direction of this magnetic field is the above-mentioned amorphous state. This coincides with the direction of the magnetic field generated by the magnetization of the soft magnetic material layer 5. That is, the magnetic field generated by the magnetization of the amorphous soft magnetic layer 5 and the magnetic field generated by the sense current I are the MR element 1.
Is applied as a bias magnetic field. This bias magnetic field rotates the magnetization of the MR element 1 with respect to the sense current I,
For the bias angle of the MR element, set θ to a predetermined value (ideally 45
To realize an MR head with excellent linear response.

(Problems to be Solved by the Invention) By the way, in the MR head having a structure in which the MR element 1, the non-magnetic conductor layer 2 and the amorphous soft magnetic layer 5 are laminated, the non-magnetic conductor layer 2 is a Ti film. , Or Mo film, or
When a Cr film is used, the heating step (300-350
There is a problem that the magnetic characteristics of the amorphous soft magnetic layer 5 or the MR element 1 are deteriorated at (.degree. C.) and the reproducing efficiency of the MR head is lowered. The heating step in the manufacturing process is performed to improve the magnetic characteristics of the amorphous soft magnetic layer 5, and the easy axis of magnetization of the amorphous soft magnetic layer 5 and the easy axis of the MR element 1 are in the same direction. This is a step required to realize a good bias level in line with the above, and is an essential step in the manufacturing process of the MR head according to the present invention.

According to the study of the present inventor, the cause of the deterioration of the characteristics in the heating step is the interface between the non-magnetic conductor layer 2 and the MR element 1 or the non-magnetic layer 2 in the heating step of the MR head manufacturing process. It has been clarified that this is because diffusion occurs at the interface with the crystalline soft magnetic material layer 5. Hereinafter, details will be referred to in this regard.

Fig. 3 shows a sample in which a NiFe film (corresponding to MR element 1) of approximately 500Å and a Ti film (corresponding to nonmagnetic conductor layer 2) of approximately 300Å are laminated in this order on a Si substrate before and after heat treatment. It is an example of the analysis result in the depth direction by the Auger analyzer. Here, the heat treatment condition was 300 ° C. for 1 hour, and the heat treatment was performed in vacuum (vacuum degree: 2 × 10 ⁻⁶ torr). Fig. 3 (a) shows the Auger analysis results before the heat treatment. The distribution of each element is clear at a depth of about 300 Å.
It can be said that the film and the Ti film are hardly diffused. On the other hand, FIG. 3 (b) shows the analysis results after the heat treatment, and FIG. 3 (a)
Compared with, the distribution of each element is broad in the depth direction, and in particular, Ti diffuses to a depth of about 600Å.

In addition, a sample in which a CoZrMo film having a film thickness of about 500Å is laminated on a Ti film having a film thickness of about 300Å is also subjected to vacuum (vacuum degree: 2
Similar diffusion of Ti was observed even after the heat treatment at × 10 ^-6 torr).

As described above, according to the Auger analysis result, due to the heating step in the manufacturing process of the MR head, diffusion occurs between the non-magnetic conductor layer 2 and the MR element or between the non-magnetic conductor layer 2 and the amorphous soft magnetic layer 5. It is considered that the magnetic characteristics of the MR element 1 or the amorphous soft magnetic material layer 5, for example, the saturation magnetization, the anisotropic magnetic field, the resistance change rate, and the like are deteriorated due to the occurrence.

Similar results were obtained for samples using Mo film or Cr film instead of Ti film, and it is considered that the deterioration of characteristics when using these materials as the magnetic conductor layer 2 is also caused by diffusion. .

Therefore, in order to solve the deterioration of the magnetic characteristics of the MR element 1 or the amorphous soft magnetic material layer 5 due to the diffusion in the heating step as described above, a material that cannot cause the diffusion even after the heating step of the manufacturing process. Is used as the non-magnetic conductor layer 2,
It is important in achieving the essential consequences of the problem.

It is an object of the present invention to provide a magnetoresistive head having excellent linear response and high reproduction efficiency without deterioration of magnetic characteristics even after a heating process.

(Means for Solving the Problems) According to the present invention, a ferromagnetic magnetoresistive effect element and an amorphous soft magnetic material layer are laminated with a nonmagnetic conductor layer interposed therebetween, A magnetoresistive head having a conductor layer made of a hafnium nitride film (hereinafter referred to as an HfN film) is obtained.

(Operation) Fig. 2 shows the heating of a sample in which a NiFe film (corresponding to MR element 1) of about 500Å and an HfN film (corresponding to nonmagnetic conductor layer 2) of about 300Å are laminated in this order on a Si substrate. It is an example of the analysis result of the depth direction by the Auger analyzer after processing. Here, the heat treatment condition was 350 ° C. for 2 hours, and the heat treatment was performed in vacuum (vacuum degree: 2 × 10 ⁻⁶ torr). As is clear from FIG. 2, even after the heat treatment, the distribution depth of each element is clear at the boundary of about 300 Å, and the NiFe film and the HfN film are hardly diffused. In addition, a film thickness of about 500Å on a Ti film with a film thickness of about 300Å
Almost the same result was obtained even after the sample having the CoZrMo film laminated thereon was heat-treated at 350 ° C. for 2 hours in vacuum (vacuum degree: 2 × 10 ⁻⁶ torr).

As described above, by using the HfN film as the non-magnetic conductor layer, diffusion between the non-magnetic conductor layer and the MR element or between the non-magnetic conductor layer and the amorphous magnetic layer can be prevented, and the MR head manufacturing process can be performed. It is possible to avoid characteristic deterioration of the MR element or the amorphous soft magnetic material layer in the heating step.

(Embodiment) FIG. 1 is a view showing an embodiment of the present invention.

In FIG. 1, a 400 Å-thick permalloy (Ni82% -Fe18%, wt%) film to be the MR element 1 is formed on a non-magnetic substrate (not shown) such as glass by using a sputtering method in an Ar gas atmosphere. A film was formed. During deposition, a magnetic field of 100 Oe was applied by a permanent magnet to give uniaxial anisotropy to the permalloy film.

Then, in a mixed atmosphere of Ar gas and nitrogen gas (flow rate conversion
A HfN film 7 having a film thickness of 300 Å to be the non-magnetic conductor layer 2 was formed on the permalloy film by a sputtering method with Ar: 100 sccm, N ₂ : 6 sccm). During film formation, a bias voltage of -80 V was applied to the substrate side to remove impurities in the HfN film, especially oxygen, and
The specific resistance of the fN film was reduced. The specific resistance of the formed HfN film was about 95 μΩcm.

Furthermore, as the amorphous soft magnetic layer 5, the amorphous soft magnetic layer 5 (Co82% -Zr6% -Mo12%, atomic%, film thickness: 300Å, CoZrMo film of anisotropic magnetic field Hk5Oe is used. Was deposited on the above HfN film 7 in an Ar gas atmosphere by a sputtering method.

After that, in order to impart uniaxial anisotropy to the amorphous soft magnetic layer 5 (CoZrMo film), the above-mentioned permalloy film, HfN film, CoZrM film
The film stack was subjected to heat treatment in vacuum at 350 ° C. for 2 hours while applying a magnetic field of 480 Oe in the same direction as the easy axis of magnetization of the permalloy film.

Next, a photoresist pattern having a predetermined shape was formed on this laminate, and ion etching was performed in an Ar gas atmosphere to form a rectangular pattern having a length of 50 μm and a width of 5 μm. Here, the etching conditions are accelerating voltage: 500 V and Ar gas pressure: 0.1 mtorr.

Then, a terminal 6 for supplying a sense current I to the above-mentioned laminated body.
Was formed by using the integrated thin film technology to fabricate an MR head. The terminal 6 uses a laminated vapor deposition film of Ti and Au, and the film thickness is 50Å and 0.5 μm, respectively.

In the MR head according to the present embodiment having the above-described structure, it was confirmed that the bias angle θ of the MR element 1 can be set to about 45 degrees when the sense current I is 5 to 15 mA, and good linear response and high reproduction are achieved. An MR head with efficiency was realized.

(Comparative Example) An MR head was manufactured in exactly the same manner as in Example except that the HfN film was changed to the Ti film. In this MR head, a permalloy film to be the MR element 1 or a CoZrMo film to be the amorphous magnetic layer 2 is formed by a heating process at 350 ° C. for giving uniaxial anisotropy to the amorphous soft magnetic layer for 2 hours. Due to the deteriorated magnetic characteristics, sufficient bias is not applied to the MR element even when a sense current of about 35 to 40 mA is applied, and the reproducing efficiency is about 35 to 50% smaller than that of the MR head according to the present invention, which is suitable for practical use. It became clear that they would not. Further, an MR head using a Cr film and a Mo film as a substitute for the HfN film was manufactured, but a sufficient bias level was not obtained as in the MR head described in this comparative example, and the embodiment of the present invention was also described. The reproduction efficiency was lower than that of the MR head.

In the above description, MR element (permalloy film), Hf
Although only the example of stacking the N film layer and the amorphous soft magnetic layer in this order is mentioned, the amorphous soft magnetic layer, the HfN film layer, the MR
An excellent linear response and high reproduction efficiency were also obtained for MR heads stacked in the order of the elements. Further, the material forming the amorphous soft magnetic layer is not limited to the CoZrMo film, and for example, a CoTaMo film, a CoZrTa film or the like may be used. Furthermore,
The HfN film forming method and film forming conditions in the examples are examples.
Other methods and conditions may be used. Of course, in this case, Hf
If the specific resistance of the N film is extremely large, the conductivity may be impaired,
Since the problem of heat generation due to Joule heat occurs, the deposited Hf
Attention should be paid to the value of the specific resistance of the N film. The specific resistance value of the HfN film depends on the design and specifications of the MR head used in the present invention and the state of the heat sink, and cannot be generally stated, but a specific resistance value of 200 μΩcm or less is desirable.

(Effects of the Invention) As described above, according to the present invention, Hf having low diffusivity is used.
By using the N film as the specific magnetic conductor layer, it is possible to avoid deterioration of the characteristics of the MR element or the amorphous soft magnetic material layer during the heating process during the MR head manufacturing process, and to achieve excellent linear response and high reproduction efficiency. The head is realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation of the present invention. 3 (a) and 3 (b) are views for explaining the problems of the conventional technique, and FIG.
It is a schematic diagram of an MR head. In the figure, 1 ... MR element, 2 ... Non-magnetic conductor layer, 5 ...
... Amorphous soft magnetic layer, 6 ... Terminal, 7 ... Hafnium nitride layer.

Claims (1)

[Claims] 1. A magnetoresistive effect head having a structure in which a ferromagnetic magnetoresistive effect element and an amorphous soft magnetic material layer are laminated via a nonmagnetic conductor layer, wherein the nonmagnetic conductor layer is formed of a hafnium nitride film. A magnetoresistive effect head characterized in that