JPH117611A - Sal bias mr head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a magnetic domain of a soft magnetic film forming a SAL film by providing two layers of soft magnetic films having a film thickness through which a switched connection magnetic field of an antiferromagnetic film is sufficiently permeable and impressing a sufficient lateral bias magnetic field on a MR film. SOLUTION: After an insulating layer 8 of a lower part reproducing gap has been formed on a lower part shield film, a tantalum film is firstly formed on this insulating film 8 as a base film 5a, and following this, a second soft magnetic film 2b of NiFeCr, an antiferromagnetic film 4 of NiMn, a first soft magnetic film 2a of NiFeCr, and a spacer 5b of tantalum film are sequentially formed in this order, and further, a NiFe film is formed thereon as an MR film 1, and finally, another tantalum film is formed again as a cap. When forming each film, a magnetic field is vertically impressed, and SAL film biasing structure is formed before a predetermined heat treatment is operated to fix a magnetization of the ferro-diamagnetic film and the SAL film to the lateral direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MR head used in the field of a magnetic recording device such as a hard disk drive, and more particularly to a SAL bias MR head capable of obtaining a linear output.

[0002]

2. Description of the Related Art A SAL biased MR head has a magnetoresistive film (hereinafter referred to as an MR film) which has a magnetic field generated by a sense current and causes the magnetization of the SAL film to be oriented in a lateral direction and is magnetically coupled to the SAL film. ) Is applied. The magnetization of the MR film is directed in a direction inclined from the vertical direction by the vertical bias magnetic field applied for fixing the magnetic domain of the MR film and the horizontal bias magnetic field. When the magnetization of the MR film is oriented in a direction inclined by about 45 ° from the longitudinal direction, the MR film generates a linear output with respect to the medium magnetic field.

FIG. 3 shows a conventional hard bias type SAL bias MR head. The figure shows an MR film 1 and an MR film 1
A sense current is supplied to the MR film 1 using the SAL film 2 adjacent to the MR film 1 and the SAL film 2 at both ends thereof as longitudinal bias films, and the permanent magnet film 3 as an electrode. The power supply 7 is provided. The medium facing surface (ABS surface) of the MR film is the surface in front of the MR film 1, the lateral direction (depth direction) represents a direction substantially perpendicular to the medium facing surface, and the vertical direction (track width direction) represents a permanent magnet. 3 indicates a direction substantially parallel to the magnetization direction 24. The tilt angle of the magnetization of the MR film, so-called bias angle, is represented by θ. The shape of the MR film shown in FIG. 3 is called a stripe.

In an MR head that applies a bias from the SAL film to the MR film, the magnitude and direction of the magnetization of the SAL film change according to the value of the sense current, and the inclination angle θ of the magnetization of the MR film changes accordingly. When the direction of magnetization of the MR film changes, the bias point changes, and the peak of the reproduction output becomes vertically asymmetric. Factors that change the magnitude and direction of the magnetization of the SAL film include a disturbance magnetic field generated by the recording operation of the magnetic head and the like in addition to the fluctuation of the sense current.

If the direction of magnetization of the SAL film can always be oriented in the horizontal direction regardless of the disturbance magnetic field as described above, the direction of magnetization of the MR film magnetically coupled to the SAL film will always be vertical. Orient at about 45 ° to the direction. At the same time, fluctuations in reproduction output and peak asymmetry can be reduced.

As prior arts for fixing the magnetic domains of the SAL film, Japanese Patent Application Laid-Open Nos. 7-230609 and 8-102
No. 017 discloses a structure in which an antiferromagnetic film is joined to a SAL film. This structure fixes the magnetization of the SAL film in the lateral direction by the exchange coupling magnetic field exerted by the antiferromagnetic film. 4 and 5 show a SAL bias MR head including the MR film 1, the spacer 5, the SAL film 2, and the antiferromagnetic film 4. This is because, in a conventional SAL bias structure, an antiferromagnetic film 4 is bonded to a side of the SAL film 2 that does not face the MR film 1 so that
This is for fixing the magnetization 23 of the AL film.

[0007]

As the recording density of the recording medium increases, the track width of the MR film becomes on the order of μm.
The aspect ratio of the stripe approaches 1. Then, it becomes more difficult to maintain the MR film in a single magnetic domain than the case where the aspect ratio is large due to the effect of shape anisotropy. When a plurality of magnetic domains are generated in the MR film, Barkhausen noise appears in the reproduced output. To reduce such noise, a larger longitudinal bias magnetic field is applied to make the stripe into a single magnetic domain. However, in the SAL bias structure, if only the longitudinal bias magnetic field is increased, the magnetization of the MR film cannot be maintained at an inclination of about 45 ° from the longitudinal direction, and a linear reproduction output cannot be obtained.

Therefore, it is necessary to increase not only the vertical bias magnetic field but also the horizontal bias magnetic field. To increase the lateral bias magnetic field, it is conceivable to increase the thickness of the SAL film to increase the saturation magnetization of the SAL film. On the other hand, when the thickness of the SAL film is increased, the magnetic domains in the thickness direction of the SAL film are insufficiently fixed, and a problem that Barkhausen noise occurs in the SAL film occurs. When Barkhausen noise occurs in the SAL film, the magnetization state of the SAL film changes to SAL.
The magnetization state of the MR film magnetically coupled to the film (magnetostatic coupling) is changed to increase the noise of the reproduction output.

In the prior art, the SAL film is joined to an antiferromagnetic film, and an exchange coupling magnetic field is applied to make the SAL film a single magnetic domain and suppress Barkhausen noise. But,
The strength of the exchange coupling magnetic field exerted on the magnetization in the SAL film by the antiferromagnetic film decreases as the distance from the interface between the SAL film and the antiferromagnetic film increases. That is, when the film thickness is increased, it becomes difficult to make the SAL film into a single magnetic domain, and a part of the magnetization of the SAL film is not fixed in the lateral direction. The magnetization that is not fixed changes its direction due to a disturbance magnetic field and causes Barkhausen noise.

FIGS. 6 and 7 show changes in the direction of magnetization of the SAL film. In joining the antiferromagnetic film 4 and the SAL film 2,
When the film thickness is large, the SAL film has multiple magnetic domains, and the magnetization directions of these magnetic domains are not aligned. FIG. 7 shows the magnetization control direction M1 of the antiferromagnetic film 4 and the magnetizations M2, M3, M4 in the SAL film 2.
FIG. 4 is a three-dimensional view showing a difference in the direction of the image. FIG. 6 is a top view of the structure of FIG. 7 as viewed from the direction perpendicular to the film surface of the antiferromagnetic film 4 (the z-axis in the figure), and the magnetization M2 closest to the antiferromagnetic film 4 overlaps M1. I can see The direction of the disturbance magnetic field is shown in FIG.
7 is the x-axis direction of the coordinates, and the horizontal direction is the y-axis direction. Of the plurality of magnetizations in the SAL film 2, the magnetization M2 close to the antiferromagnetic film 4 is fixed in the lateral direction by the exchange coupling magnetic field, but the magnetization position is the antiferromagnetic film like M3 and M4. 4, the exchange-coupling magnetic field becomes weaker, and the direction of magnetization becomes more likely to be directed to a direction other than the lateral direction due to the influence of the external magnetic field.

On the other hand, if the thickness of the SAL film is reduced in order to sufficiently fix the magnetic domain in the entire SAL film, the total saturation magnetization of the SAL film cannot be increased and a larger lateral bias magnetic field cannot be applied to the MR film. Accordingly, the present invention provides an SAL film while sufficiently fixing the magnetization of the SAL film using an antiferromagnetic film.
An object is to apply a lateral bias magnetic field to the MR film by increasing the total amount of saturation magnetization of the film.

[0012]

According to the present invention, the SAL film is composed of two soft magnetic films, and an antiferromagnetic film is arranged between these soft magnetic films to thereby reduce the magnetization of the SAL film. Is provided in the SAL bias MR head for fixing the horizontal direction. The structure of the present invention including the multilayer film joined in the order of the MR film, the spacer, the first soft magnetic film, the antiferromagnetic film, and the second soft magnetic film has a structure in which the exchange coupling magnetic field of the antiferromagnetic film sufficiently reaches. By providing two soft magnetic films having a thickness of
While applying a sufficient lateral bias magnetic field to the R film,
The magnetic domains of the soft magnetic film constituting the L film can be fixed.

Further, by disposing an antiferromagnetic film between the soft magnetic films, both surfaces of the antiferromagnetic film can be used for fixing magnetic domains. To fabricate the junction between the SAL film and the antiferromagnetic film,
The direction of the anisotropy of the antiferromagnetic film is formed in a magnetic field or subjected to a heat treatment in a magnetic field, so that the magnetization direction of the SAL film is fixed to the direction of the anisotropy of the antiferromagnetic film. When the magnetization of the SAL film is fixed by the above function of the antiferromagnetic film, the direction of the magnetization of the SAL film does not change even if there is a fluctuation in the sense current or a disturbance magnetic field, and the SAL film is magnetically coupled to the SAL film. The direction of magnetization of the existing MR film does not change.

The present invention improves the crystallinity of the SAL film and the antiferromagnetic film by using a tantalum film as a base film when providing an MR film and a SAL bias structure between shields via an insulating film. it can. Specifically, a lower shield, an insulating film, a tantalum film, a second soft magnetic film, an antiferromagnetic film, a first soft magnetic film, a spacer, an MR film, a cap, an insulating film, and a mid shield are stacked in this order. However, in such a multilayer structure, as the number of films to be stacked increases, the smoothness and crystallinity of the films tend to deteriorate. In order to exhibit the magnetic properties required for the SAL film and the antiferromagnetic film, it is necessary to maintain specific crystal structures such as fcc (face-centered cubic lattice) and fct (face-centered square lattice), respectively. Therefore, in the present invention, the crystallinity of the SAL film and the antiferromagnetic film is maintained by using a tantalum base film when stacking a multilayer structure.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a sectional view of a SAL bias MR head according to the present invention. In this MR head, after forming an insulating layer 8 of a lower reproducing gap with a thickness of 90 [nm] on a lower shield film, a tantalum film of a base film 5a is first formed on the insulating layer 8 with a thickness of 3 [nm]. Then, it was formed by a sputtering method.
Then, using the same sputtering apparatus, the NiFeCr film of the second soft magnetic film 2b has a thickness of 5 [nm], and the NiMn of the antiferromagnetic film 4 has a thickness of 30 [nm]. 2a
After forming a NiFeCr film with a thickness of 15 [nm],
Further, using the same sputtering apparatus, a tantalum film of the spacer 5b was formed with a thickness of 10 [nm], and subsequently, a NiFe film was formed as the MR film 1 with a thickness of 20 [nm]. Finally, a 3 nm thick tantalum film was formed again as a cap. When forming each film, a magnetic field is applied in the vertical direction, and after forming the SAL bias structure, a magnetic field is applied in the horizontal direction and a heat treatment at 250 ° C. is performed for 3 hours.
The magnetization of the L film was fixed in the lateral direction.

In order to process the seven-layer film formed by continuous sputtering as described above into a stripe shape, the film was processed by ion milling using a patterned photoresist as a mask. Next, a CoCrPt film of a permanent magnet film 3 for longitudinal bias was formed to a thickness of 40 [nm] in the off-track region of the stripe subjected to ion milling. Further, a Mo film was formed as the electrode 6. After the electrodes were formed, a magnetic field was applied in the vertical direction at room temperature to fix the magnetization of the permanent magnet film 3 in the vertical direction.

On the MR stripe formed by the above method, an insulating layer of an upper reproducing gap was formed with a thickness of 90 [nm], and the formation of the MR element portion was completed. Although not described in detail, a recording section including a coil and an upper magnetic pole was formed on the MR element section, and the wafer process of the MR head was completed. The description of the shield is omitted. FIG. 8 shows an elevation view of the MR head including the recording section. The SAL bias structure is disposed between the lower shield 9 and the mid shield 10. The mid shield and the upper magnetic pole 12 constitute a magnetic circuit for recording, and the coil 13 is wound around the magnetic circuit. In FIG. 8, the description of the interlayer insulating film is omitted.

Thereafter, the wafer is subjected to MR process in a slider process.
The height (depth) is polished to a predetermined size, and the ABS
The surface (media facing surface) was subjected to levitation processing. Further, the slider is fixed to the suspension 52, and the head is provided with an HGA (head gimbal assembly).
The head HGA was completed. FIG. 9 shows a three-dimensional view of a slider having an MR head. The MR head of FIG. 8 is located on the outflow end side 50 of the ABS surface 51 of the slider.

FIG. 10 shows an MR head according to the first embodiment in which the SAL film is composed of two soft magnetic films, and a conventional M head having one SAL film.
For the R head, the characteristics of the reproduction output variation (%) of the MR head with respect to the total thickness of the SAL film and the track width converted reproduction output (μV / μm) are shown. The MR head of the first embodiment has a lower reproduction output fluctuation and an increased track width converted reproduction output as compared with the conventional MR head. Further, when the specifications required for the MR head are 2 (%) or less in reproduction output fluctuation and 200 (μV / μm) or more in track width converted reproduction output, the MR head of the first embodiment is different from the conventional MR head. In comparison, the range of available total SAL film thickness has been expanded. This range is indicated by an arrow in FIG.

(Embodiment 2) FIG. 2 is a sectional view of a SAL bias MR head according to the present invention. In this MR head, an insulating layer 8 of a lower read gap is formed on the lower shield film by 90 [n].
m], a tantalum film as a base film 5a was first formed on this insulating layer to a thickness of 3 [nm] by a sputtering method. Then, the MR film 1 was formed using the same sputtering apparatus.
Is formed to a thickness of 20 [nm], and then a tantalum film of the spacer 5b is formed to a thickness of 10 [nm] by using the same sputtering apparatus, and then as a first soft magnetic film 2a. A NiFeCr film is formed with a thickness of 15 [nm], a NiMn film of the antiferromagnetic film 4 is formed with a thickness of 30 [nm], and NiFeCr is formed as a second soft magnetic film 2b.
The film was formed with a thickness of 5 [nm]. Finally, cap 5c
Then, a 3 [nm] tantalum film was formed again. The direction of the magnetic field during the sputtering and the process of forming the electrodes 6 and the like are the same as in the first embodiment.

(Embodiment 3) An MR head in which the thickness range of the first soft magnetic film and the second soft magnetic film in the first or second embodiment is 4 to 30 [nm].

(Embodiment 4) In the embodiment 1 or 2, the conductive FeMn, NiMn, CoMn,
PtMn, IrMn, FeMn, NiMn, CoM
An MR head using an antiferromagnetic film made of n-based, PtMn-based, IrMn-based, or a mixed phase thereof.

(Example 5) In Example 1 or Example 2, NiO, CoO, NiO-based,
An MR head using an antiferromagnetic film made of O-based or a mixed phase thereof.

As described above, the SAL of the present invention
The bias MR head applies a sufficient lateral bias magnetic field to the MR film while suppressing Barkhausen noise in the SAL bias by fixing the magnetization of the two soft magnetic films in the lateral direction with the antiferromagnetic film. As a result, noise of the output of the MR element due to Barkhausen noise of the SAL film can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a SAL bias MR head according to the present invention.

FIG. 2 is a sectional view of a SAL bias MR head according to the present invention.

FIG. 3 is a sectional view of a conventional SAL bias MR head.

FIG. 4 is a sectional view of a conventional SAL bias MR head.

FIG. 5 is a sectional view of a conventional SAL bias MR head.

FIG. 6 shows the relationship between the magnetization of the SAL film and the magnetization of the antiferromagnetic film.

FIG. 7 shows the relationship between the magnetization of the SAL film and the magnetization of the antiferromagnetic film.

FIG. 8 is a cross-sectional view of the MR head including a recording unit.

FIG. 9 is a three-dimensional view of a slider including an MR head.

FIG. 10 shows the reproduction output fluctuation of the MR head with respect to the thickness of the SAL film and the characteristics of the reproduction output in terms of track width.

[Explanation of symbols]

1 MR film, 2 SAL film, 2a First soft magnetic film, 2
b second soft magnetic film, 3 permanent magnet film, 4 antiferromagnetic film, 5a under film, 5b spacer, 5c cap,
6 electrodes, 7 power supply, 8 insulating layer, 9 lower shield,
Reference Signs List 10 mid shield, 12 upper magnetic pole, 13 coil, 21 MR film magnetization, 21a longitudinal component of MR film magnetization, 21b transverse component of MR film magnetization, 22 sense current magnetic field, 23 SAL film magnetization, 24 permanent Magnet magnetization, 27 direction in which exchange coupling magnetic field fixes magnetization of SAL film, 50 outflow end where MR head is located, 51 ABS surface of slider, 52 suspension

Claims (3)

[Claims] A magnetoresistive film; a SAL film for laterally biasing the magnetoresistive film; a magnetoresistive film;
In the MR head having a spacer for separating a film, a permanent magnet film for vertically biasing the magnetoresistive film, an electrode for supplying a sense current to the magnetoresistive film, and an upper magnetic pole for recording, the SAL film Comprises a first soft magnetic film and a second soft magnetic film, and an antiferromagnetic film is disposed between the first and second soft magnetic films.
R head. 2. The SAL bias MR head according to claim 1, wherein the magnetic domain of the SAL film is fixed in a lateral direction. 3. The SAL bias MR head according to claim 1, wherein said first soft magnetic film has a larger thickness than said second soft magnetic film and is close to said magnetoresistive film. Characteristic SAL bias MR head.