JPH0916917A - Magneto-resistive magnetic head and its production - Google Patents

Abstract

PURPOSE: To improve the reproducing characteristics of an MR head by incorporating gaseous nitrogen into an SAL film to lower a magneto-resistive effect and magnetostrictive effect. CONSTITUTION: The SAL film is formed by using a sputtering method and a sputtering gas contg. nitrogen is used, by which >=Swt.% gaseous nitrogen is included into the SAL film. More specifically, an RF magnetron sputtering device of a load lock type is used and the gaseous nitrogen content in gaseous Ar is controlled within a range of 0 to 20% by changing the nitrogen content in the film while the gaseous pressure is maintained constantly under 0.2Pa. The nitrogen-contg. SAL film exhibits a tendency to lowering of magnetostriction and intrinsic resistance change rate with an increase in the nitrogen content. The magneto-resistive effect of the MR film is lowered to <=1/10 and the nitrogen content to decrease the magnetostriction to <=2×10<-7> is 3wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive effect magnetic head used in a magnetic disk device or the like,
A soft magnetic film that generates a lateral bias magnetic field (Soft Adjacent
Hereinafter, abbreviated as SAL film. ) Composition and its manufacturing method.

[0002]

2. Description of the Related Art In recent years, the magnetic recording technology has made remarkable progress. For example, in the field of home VTRs, the recording density is high in order to reduce the size and weight, and in the field of magnetic disk devices to reduce the size and increase the capacity. As a result, the magnetoresistive effect type magnetic head and the like are being put to practical use.

Taking a magnetic head for a magnetic disk device as an example, a recording operation is further induced from a ring type ferrite magnetic head in which recording / reproducing operation is performed by the same head or an induction type thin film magnetic head applying photolithography technology. Type thin film magnetic head, and a reproducing operation is being progressed to a recording / reproducing separated type magnetic head in which a reproducing operation is performed by a magnetoresistive effect type magnetic head (hereinafter abbreviated as MR head).

In order to reduce the size of the magnetic disk device, it is effective to reduce the outer diameter of the magnetic disk, which is a magnetic recording medium, but the relative speed between the magnetic recording medium and the magnetic head decreases. The conventional ring type ferrite magnetic head and induction type thin film magnetic head have a problem that it is difficult to obtain a sufficient output. On the other hand, the MR head is characterized in that its output does not depend on the relative speed and is constant regardless of the relative speed. Therefore, it can be said that the improvement of the performance of the MR head is an essential issue in response to the demand for further miniaturization of the magnetic disk device.

An MR head is a magnetoresistive effect element (hereinafter,
The MR element (abbreviated as MR element) utilizes a phenomenon that its electric resistance value is changed by a magnetic field from a recording medium, and is a so-called read-only head. For this reason, an inductive thin film head is usually provided as a recording-only head at the same position as the MR head. In the MR head, the polarity of the signal magnetic field from the recording medium is determined, and at the same time, a large reproduction output is obtained.
The operating point is selected approximately in the center of the linear region on the magnetoresistive response curve. Therefore, it is necessary to apply a bias magnetic field to the MR element.

As a bias magnetic field applying method, a self method, a hard film method, a shunt method, a barber pole method, a soft film bias method and the like are known, and the soft film bias method is the mainstream at present. In all of these bias methods, a lateral bias is applied so that the magnetization vector and the current vector of the MR element form a constant angle (about 45 °). FIG. 5 shows a schematic configuration of an MR head to which the soft film bias method is applied.

In FIG. 5, the MR head 1 is mounted on the substrate 30.
0 shows a schematic structure of a recording / reproducing separation type magnetic head in which the thin film magnetic head 20 of 0 and the induction type thin film magnetic head 20 is mounted. During recording, the coil 22 of the inductive thin film magnetic head 20 on the upper side
A recording current is applied to the recording medium (not shown) through the magnetic gap 26 for recording. On the other hand, during reproduction, the recording magnetic field written as information is read by the MR element 15 of the lower MR head 10. FIG. 6 is an enlarged view of the MR element 15 part. That is, the SAL film 16, the non-magnetic film 14, and the MR film 14 are formed on the insulating layer 34.
Is a three-layer structure in which is laminated. Further, electrodes 18 are arranged on both ends of the MR film 12 to supply a sense current and a bias current.

The soft film bias method is a bias method utilizing magnetic coupling with a soft magnetic film arranged adjacent to the MR element. The SAL film 16 is magnetized by the sense current injected from the electrode 18, and as a result, a bias magnetic field is applied in the lateral direction of the MR element. MR
Of the sense current flowing through the element, S from the MR film 12
Since a large amount of shunt to the AL film 16 causes a reduction in reproduction output, it is preferable that the specific resistance of the SAL film 16 be larger than that of the MR film 12. The SAL film 16 has the MR film 1
At the same time as 2, the magnetic field from the recording medium is received, and if the rate of change of the specific resistance due to the magnetoresistive effect of the SAL film is large, M
The reproduction output of the R element decreases. Therefore, the smaller the resistivity change rate due to the magnetoresistive effect of the SAL film, the better. As is clear from the above description, the SAL film is required to have the opposite characteristics to the MR film, and the structure of the magnetic head is required to have a low magnetostriction.

One of the problems peculiar to the conventional MR head is the reduction of Barkhausen noise. A NiFe film is usually used as the MR film of the MR head.
The magnetic domain structure of the magnetic substance such as the e-film is in a reflux type multi-domain state so that the magnetic energy is minimized. When a magnetic field from the recording medium is applied, the domain begins to rotate and domain wall movement progresses, but the domain wall movement is impeded by impurities and defects in the film, and the response curve of the magnetoresistance effect becomes discontinuous. It begins to show a phenomenon. As a result, the reproduced output waveform is distorted, which causes an increase in noise. These are collectively called Barkhausen noise. Barkhausen noise is not a problem related only to the MR element, but is also greatly affected by the SAL film made of the same magnetic material as the MR element. The cause of the increase in magnetic domains is a large coercive force. There are many defects in the film. Large magnetostriction. There are several factors.

[0010]

NiF as a SAL film
Although there is an example in which a large amount of e is used, it is poor in practicality such that the reproduction output of the MR element is lowered due to the shunting of the sense current flowing in the MR element to the SAL film. In order to increase the specific resistance and reduce the rate of change in magnetic resistance, NiFe is replaced with Nb, Z
There are some examples in which r and the like are added, but the behavior of magnetostriction is not mentioned (MM Chen, et al .:
J. Appl. Phys. 69 (8), 5631 (19
91)).

The present inventor has used Nb and Zr for NiFe alloys.
And thin films each containing 0 to 6 wt% of Cr were formed, and the specific resistance change rate, the specific resistance, and the magnetostriction were measured. The results are shown in FIGS. However, good results were not obtained even if the addition amount of any of the additive elements was increased. As shown in FIGS. 7 and 8, when the above elements are added, the rate of change in specific resistance decreases and the specific resistance can be increased, but as the number of added elements increases, as shown in FIG. It was found that the magnetostriction increased significantly from negative to positive.

As a result of simulation, it has been found that there is no practical problem if the rate of change in specific resistance of the SAL film is one digit or more, that is, 1/10 or less of the MR element. In the result of FIG. 7, since the change rate of the magnetoresistance without addition is about 2.2%, it is about 0.0.
The target value is 22% or less. It can be seen that the addition amount satisfying this target value is about 7 wt% for Zr, about 6 wt% for Nb, and about 4.5 wt% or more for Cr. Further, from FIG. 9, the respective magnetostrictions at that time were 10, 6 and 7 × 10 ⁻⁷ or more. Therefore, it has been revealed that it is difficult to control the magnetostriction to near zero while satisfying the target value of the specific resistance change rate regardless of which element is used.

[0013]

The present invention is characterized by applying a sputtering method to a SAL film and using a sputtering gas containing nitrogen so that the SAL film contains 3 wt% or more of nitrogen gas. I am trying.

[0014]

Function: Magnetostriction is affected by the composition of components, crystal structure, crystal orientation, ordered / disordered lattice, and the like. As a result of various studies focusing on the crystal orientation, the present inventor has revealed that the crystal orientation of NiFe changes from the (111) plane orientation to the (200) plane orientation as the content of nitrogen gas increases. Further, they found that the magnetostriction decreased with the change of orientation. (See FIGS. 1 and 3) Here, a gas analyzer was used to measure the nitrogen content.

When the amount of nitrogen in the film increases, the rate of change of the specific resistance, which is a measure of the magnetostriction and the magnetoresistive effect, decreases, which is a desirable characteristic, but the saturation magnetic flux density decreases and there is an upper limit of the nitrogen content. Practically 2 to 10 wt%, 3 to
10 wt% is the optimum range.

[0016]

EXAMPLES Two types of sputtering devices were used as film forming devices. That is, when the film composition is changed, a batch type RF magnetron sputter is used to produce N with a diameter of 5 inches.
10 mm square N in the erosion part of the iFe target
The b, Zr and Cr chips were respectively arranged to form a film. The NiFe target is 82.8 wt% Ni-ba.
1Fe was used. Ar gas pressure during film formation is 0.4P
a, input power density is 6.3 W / cm ² . The ultimate vacuum before film formation is 3 × 10 ⁻⁵ Pa or less, and the substrate temperature is about 10
It was kept at 0 ° C.

On the other hand, when nitrogen is introduced to form a film, a load lock type RF magnetron sputtering apparatus is used, the target has a diameter of 6 inches, and the composition is 78.5Ni-.
17.5Fe-4wt% Cr was used. The gas pressure is 0.
In order to change the amount of nitrogen in the film while keeping it constant at 2 Pa, it was decided to control the amount of nitrogen gas in the Ar gas within the range of 0 to 20%. The applied power density is 3.3 W / cm ² . The ultimate vacuum before film formation was 2 × 10 ⁻⁵ Pa or less.
The substrate temperature is room temperature. The substrate material is a 3 inch diameter Si wafer with an oxide film.

FIG. 1 shows the relationship between the nitrogen content in the film and the magnetostriction. It can be seen that the magnetostriction tends to decrease as the nitrogen content increases. FIG. 2 shows the relationship between the nitrogen content and the rate of change in specific resistance. Similar to magnetostriction, the rate of change in specific resistance also tends to decrease as the content of nitrogen increases. As is clear from the confirmation by the experiments of FIGS. 1 and 2, if nitrogen is contained in the SAL film, it is possible to simultaneously reduce the contradictory characteristics of magnetostriction and specific resistance change rate.

1 and 2 that the nitrogen content that can reduce the magnetoresistive effect of the MR film to 1/10 or less and the magnetostriction to 2 × 10 ⁻⁷ or less is 3 wt% or more. it is obvious. Referring to the X-ray diffraction result of FIG. 3, it can be seen that the crystal orientation changes depending on the nitrogen content. When the nitrogen content is zero, the crystal orientation is the (111) plane orientation. However, in the case of 5 wt%, the (111) plane orientation almost disappears and, instead, the (200) plane orientation occurs slightly. Further, if it is 10 wt%, only (200) plane orientation is obtained.

[0020]

As is apparent from the above description, by applying the present invention, the reduction of the magnetostriction and the specific resistance change rate of the SAL film, which is a contradictory characteristic in the prior art, is contained in the film. Can be achieved by Since the film is formed by the sputtering method in an atmosphere containing nitrogen gas or a mixed gas of argon and nitrogen, the manufacturing method can be easily and accurately controlled. This leads to improvement of reproduction characteristics of the MR head.

[Brief description of the drawings]

FIG. 1 shows the relationship between nitrogen content and magnetostriction according to the present invention.

FIG. 2 shows the relationship between the nitrogen content and the rate of change in specific resistance according to the present invention.

Fig. 3 Nitrogen content and X-ray diffraction pattern during NiFe film formation
Relationship.

FIG. 4 is a relationship between nitrogen content and saturation magnetic flux density.

FIG. 5 shows a structure of a recording / reproducing separated magnetic head.

FIG. 6 is an enlarged view of an MR element portion of a magnetoresistive effect magnetic head.

FIG. 7 shows the relationship between the content of various additive elements and the rate of change in specific resistance.

FIG. 8 shows the relationship between the content of various additive elements and the specific resistance.

FIG. 9 shows the relationship between the content of various additive elements and magnetostriction.

Claims (5)

[Claims] 1. A soft magnetic film (SAL film), a non-magnetic film and a magnetoresistive effect film (MR) on an insulating layer formed on the surface of a substrate.
A magnetoresistive head having a magnetic shielding film and a protective film, wherein the SAL film contains nitrogen gas and the magnetoresistive resistance is increased. A magnetoresistive effect magnetic head characterized by reducing the effect and the magnetostrictive effect. 2. The SAL film according to claim 1, wherein the SAL film is Ni.
A magnetoresistive effect magnetic head comprising an Fe-based alloy and containing 3 wt% or more of nitrogen gas. 3. The resistivity change rate due to the magnetoresistive effect of the SAL film according to claim 2, which is one of that of the MR film.
/ 10 or less, or a magnetoresistive head, wherein the magnetostriction is 3 × 10 ^-7 or less. 4. The SAL according to claim 2 or 3,
A magnetoresistive magnetic head characterized in that the saturation magnetic flux density of the film is 0.5 T (tesla) or more. 5. The magnetoresistive device according to claim 1, wherein the SAL film is formed by a sputtering method in an atmosphere containing nitrogen gas or a mixed gas of argon and nitrogen. Method of manufacturing effective magnetic head.