JP2000113416A - Magnetoresistive head and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a head in which a Barkhausen noise can be suppressed while making a magnetic variation characteristic good. SOLUTION: A lower part shield layer 3 and a lower part insulation layer 4 are formed at the upper side of an AlTiC substrate 1. A soft magnetic layer 6 is formed on the surface of the lower insulation layer 4. When this soft magnetic layer 6 is formed, a target is arranged on the axis being tilted from the axis being perpendicular to the surface of the substrate 1 only at a prescribed angle and sputter is performed. A non-magnetic layer 7 and a fixed layer 8 are formed on the surface of the soft magnetic layer 6 by overhead filming and a spin valve film 5 is formed. Then, a hard bias layer 9a and an electrode layer 9b of a prescribed pattern are successively formed at the side of the spin valve film 5. Then, an upper part gap layer and an upper part shield layer are formed on the surface of the lower part insulation layer on which the spin valve layer and the electrode layer are formed, further, the prescribed layer is formed and a magnetoresistive head is manufactured by cutting it at a prescribed position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head used for reproducing data recorded on a magnetic recording medium such as a magnetic disk and a method of manufacturing the same. The present invention relates to a configured magnetoresistive head and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 1 shows an example of the structure of a magnetoresistive head constituted by using a spin valve film. When such a magnetoresistive head is manufactured, predetermined patterned layers are sequentially formed on a substrate by utilizing a semiconductor manufacturing process. With reference to FIG. 1, a method of manufacturing a conventional magnetoresistive head will be described. On the upper surface of the Altic substrate 1, a substrate protective layer 2, a lower shield layer 3, and a lower gap layer 4 are formed. A spin valve film 5 is formed at a predetermined position on the upper surface of the lower gap layer 4.

The process of forming the spin valve film 5 will be described. First, a soft magnetic layer 6 is formed on the upper surface of the lower gap layer 4 by sputtering. At this time, both the target for forming the soft magnetic film and the center position of the Altic substrate 1 are arranged so as to coincide with each other. To form Then, the non-magnetic layer 7 is formed on the upper surface of the soft magnetic layer 6 and the fixed layer 8 is formed on the upper surface of the non-magnetic layer 7, whereby the spin of the soft magnetic layer 6, the non-magnetic layer 7, and the fixed layer 8 is formed. The valve film 5 is formed.
Each of the above layers is actually formed on the entire surface and then patterned to form each layer having a predetermined shape. The fixed layer 8 is formed by laminating an antiferromagnetic layer 8b on the soft magnetic layer 8a.

Then, the upper surface of the fixed layer 8 is partially covered so as to be in contact with the side surface of the spin-valve film 5.
A hard bias layer 9a made of a permanent magnet film is formed on the upper surface of the lower gap layer 4, and a low-resistance electrode layer 9b is formed on the upper surface of the hard bias layer 9a to form the electrode section 9. The electrode section 9 has a function of applying a magnetic field to the spin valve film 5 (soft magnetic layer 6) to make the soft magnetic layer 6 a single magnetic domain (realized by the hard bias layer 9a). A function of flowing a current and measuring a resistance change of the spin valve film 5 (mainly, the electrode layer 9
b).

The magnetization directions of the soft magnetic layers 6 and 8a are controlled so that the magnetization direction of the soft magnetic layer 6 is parallel to the current direction. The direction of magnetization of the soft magnetic layer 8a is controlled by the magnetic field of the antiferromagnetic layer 8b to be perpendicular to the current direction.

Then, an upper insulating layer 10 and an upper shield layer 11 are sequentially laminated on the upper surfaces of the spin valve film 5 and the electrode section 9. Above the upper shield layer 11,
A magnetoresistive head is manufactured by forming a protective film or a write portion and cutting at a predetermined position.

[0007]

The magnetoresistive head manufactured by the above-mentioned conventional method for manufacturing a magnetoresistive head has the following problems. That is, while the thickness (in the vertical direction in FIG. 1) of the soft magnetic layer 6 is about several tens angstroms to several hundred angstroms, the length (FIG.
(Middle, left-right direction) is about 0.8 μm to 2 μm, and is very thin and long. The anisotropic magnetic field of the soft magnetic layer 6 is about 3 to 8 [Oe]. On the other hand, the thickness of the lower insulating layer 4 and the upper insulating layer 10 is 1
The lower shield layer 3 and the upper shield layer 11, which are as thin as about 000 angstroms and are several microns in thickness, are adjacent to each other. Therefore, rather than passing straight through the soft magnetic layer 6,
It is magnetically advantageous to flow over the lower insulating layer 4 and the upper insulating layer 10 and flow to the lower shield layer 3 and the upper shield layer 11.

As a result, as shown by an arrow (solid line) in FIG. 4, the magnetic flux from the hard bias layer 9 a passes through the lower insulating layer 4 while flowing through the soft magnetic layer 6, and Will flow into. Therefore, the magnetic flux from the hard bias layer 9a cannot flow straight into the soft magnetic layer 6 in the same direction, and the magnetic flux flows only at the end of the soft magnetic layer 6, and no magnetic flux flows in the middle. As shown in FIG. 5, a plurality of magnetic domains are generated in the soft magnetic layer 6. Therefore, the magnetic domain walls of the soft magnetic layer 6 move when reading magnetic data, and Barkhausen noise is generated.

The present invention has been made in view of the above background, and has as its object to solve the above problems and to suppress Barkhausen noise while maintaining good characteristics. An object of the present invention is to provide a magnetoresistive head and a method of manufacturing the same.

[0010]

In order to achieve the above object, a magnetoresistive head according to the present invention includes a lower shield layer and a lower insulating layer on a substrate in that order, and a soft upper surface of the lower insulating layer. A spin valve film including a magnetic layer, a non-magnetic layer, and a fixed layer; a hard bias layer formed on a side of the spin valve film; an upper insulating layer on an upper surface of the spin valve film and the hard bias layer; A magnetoresistive head including an upper shield layer in this order, wherein the anisotropic magnetic field of the soft magnetic layer is set to 20 [Oe] or more.

The magnetic flux that has flowed into the soft magnetic layer from the hard bias layers provided on both sides of the spin valve film,
The soft magnetic layer flows into the shield layer 3 and the upper shield layer 11, but since the anisotropic magnetic field of the soft magnetic layer is as large as 20 [Oe] or more, no domain wall is generated in the soft magnetic layer, and the soft magnetic layer is formed into a single magnetic domain. You. Therefore, occurrence of Barkhausen noise is reduced as much as possible, and the non-defective product rate is improved. The occurrence rate of Barkhausen noise can be suppressed as the anisotropic magnetic field increases.

The lower limit of the anisotropic magnetic field is set to 20 [Oe].
The reason for this is that if the anisotropic magnetic field is smaller than 20 [Oe], the yield of Barkhausen noise is high, and the yield of the magnetoresistive head is extremely low.

[0013] As a result of experiments, it has been confirmed that if the anisotropic magnetic field of the soft magnetic layer is too large, the MR ratio is degraded. Therefore, when the anisotropic magnetic field is set to 50 [Oe] or less, This is preferable because Barkhausen noise can be suppressed while effectively maintaining the MR ratio.

According to the experimental results of the present invention, when the anisotropic magnetic field is set to 20 [Oe] or more, Barkhausen noise does not occur. This is advantageous in that all elements can be used and there is no variation.

As a method of manufacturing the above-described magnetoresistive head, a lower shield layer is formed directly or via a predetermined layer on an upper surface of a substrate, and a lower gap layer is formed on an upper surface of the lower shield layer. Forming a spin valve film by laminating a soft magnetic layer, a non-magnetic layer, and a fixed layer in this order on the upper surface of the gap layer; patterning a hard bias layer on the side of the spin valve film; Forming an upper insulating layer on the upper surface of the layer and forming an upper shield layer on the upper surface of the upper insulating layer, wherein the soft magnetic layer is formed on a surface on which a film is to be formed. It is formed by oblique film formation in which atoms are incident from an angle inclination direction (claim 2).

The oblique film formation is, as defined in the claims, a method in which atoms are obliquely incident on a film formation target surface and a film is formed while attaching atoms to the target surface. It is. As a specific method, for example, the target is arranged such that the center is located on an axis inclined at a predetermined angle with respect to a normal line (passing through the center of the substrate) of the surface of the substrate on which the predetermined layer is formed. When the soft magnetic layer is formed in this state, the atoms constituting the soft magnetic layer enter from an oblique direction, that is, the oblique film formation can be performed. The angle of incidence (the angle formed with the normal to the substrate surface) varies depending on the angle of the shift.

Conventionally, a film is generally formed by injecting atoms perpendicularly (at an incident angle of 0 °) to a surface to be formed. The feature is that a magnetic layer is formed. The arrangement of the atoms in the soft magnetic layer formed by the oblique film formation was formed by any one of the film formation methods of the direct film formation, the rotation film formation, and the rotation film formation (in each case, the incident angle of the atoms was 0 degree). Unlike the arrangement of the atoms in the soft magnetic layer, it is stable. As a result of the experiment, it was confirmed that the strength of the anisotropic magnetic field of the formed soft magnetic layer was adjusted depending on the incident angle.

Then, the anisotropic magnetic field of the soft magnetic layer is set to 20 to 5
By adjusting the value within the range of 0 [Oe], the inside of the soft magnetic layer is formed into a single magnetic domain while maintaining the characteristics of the magnetoresistive head satisfactorily, so that Barkhausen noise is suppressed as much as possible. .

According to another magnetoresistive head for achieving the above-mentioned object, a lower shield layer and a lower insulating layer are provided on a substrate in this order, and a base layer is formed on the upper surface of the lower insulating layer. A spin valve film formed by laminating a layer, a non-magnetic film, a soft magnetic layer, and an anti-strong pinned layer in this order. The soft magnetic layer is formed on an upper surface of an underlayer, and a hard magnetic layer is formed beside the spin valve film. A bias layer is formed, and an upper insulating layer is formed on the spin valve film and the hard bias layer.
Even in a magnetoresistive head having an upper shield layer in this order, the anisotropic magnetic field of the soft magnetic layer is set to 20 [Oe] or more.

That is, even in the type in which the underlayer is provided under the soft magnetic layer, a single magnetic domain can be formed by increasing the anisotropic magnetic field of the soft magnetic layer, and the Barkhausen noise is reduced. Can be suppressed as much as possible.

According to a third aspect of the present invention, there is provided a method of manufacturing a magnetoresistive head, wherein a lower shield layer is formed directly or via a predetermined layer on an upper surface of a substrate, and a lower gap layer is formed on the upper surface of the lower shield layer. Forming an underlayer on the upper surface of the lower gap layer, laminating a soft magnetic layer, a nonmagnetic layer, and a fixed layer on the upper surface of the underlayer in this order to form a spin valve film; Forming a hard bias layer on the sides of the magnetoresistive head, forming an upper insulating layer on the spin valve film and the hard bias layer, and forming an upper shield layer on the upper insulating layer. The method according to claim 1, wherein the underlayer is formed by oblique film formation in which atoms are incident on a surface to be film-formed at a predetermined angle.

Since the soft magnetic layer constituting the spin valve film is formed on the upper surface of the underlayer, the atomic arrangement of the soft magnetic layer is affected by the atomic arrangement of the underlayer. By forming the underlayer by oblique film formation, the atomic arrangement of the soft magnetic layer formed on the upper surface of the underlayer is stabilized, and the anisotropic magnetic field of the soft magnetic layer is strengthened. By adjusting the angle of the oblique film formation of the underlayer, the strength of the anisotropic magnetic field of the soft magnetic layer can be controlled. The method of forming the underlayer obliquely is the same as the method of forming the soft magnetic layer in the method of manufacturing a magnetoresistive head according to claim 2.

[0023]

FIG. 1 shows a main part of a magnetoresistive head according to the present invention. As shown in the figure, a lower shield layer (sendust) 3 is formed on an upper surface of an Altic substrate 1 via a substrate protective layer 2 made of alumina. A lower insulating layer (alumina) is formed on an upper surface of the lower shield layer 3. 4 are formed. On the upper surface of the lower insulating layer 4, a spin valve film 5, which is a magnetoresistive sensor unit, is formed directly.

The spin valve film 5 is formed of a soft magnetic layer (Ni
Fe) 6, a non-magnetic layer 7, and a fixed layer 8 are laminated in that order. Further, the fixed layer 8 includes a soft magnetic layer (N
iFe) 8a and the antiferromagnetic layer 8b are laminated in this order. Further, a protective cap layer (not shown) made of Ta is formed on the upper surface of the antiferromagnetic layer 8b so as to prevent corrosion of the antiferromagnetic layer 8b.

A hard bias layer 9 a is formed so as to be in contact with both side end surfaces of the spin valve film 5. A magnetic field in a fixed direction is applied to the spin valve film 5, and the soft magnetic layer 6 forming the spin valve film 5 is formed. Are single domain.
Further, an electrode layer 9b is formed on the upper surface of the hard bias layer 9a, and it is possible to flow a current to the spin valve film 5 through the electrode layer 9b. The electrode section 9 is constituted by the hard bias layer 9a and the electrode layer 9b.

Although not shown, an upper insulating layer and an upper shield layer are formed on the upper surface of the spin valve film 5, the electrode portion 9, and the exposed lower insulating layer 4 (the structure is equivalent to that of FIG. 4). A predetermined layer is formed on the upper surface of the upper shield layer, and a write section is formed, thereby constituting a magnetoresistive head according to the present invention.

The soft magnetic layer 6 is formed of a soft magnetic material (NiFe), and the magnetization direction of the soft magnetic layer 6 changes under the influence of the magnetic field of the magnetic data recorded on the magnetic recording medium. On the other hand, the soft magnetic layer (NiFe) constituting the fixed layer 8
8a is an antiferromagnetic layer (FeMn, I
rMn, at least one of PtMn)
The magnetization direction is controlled and fixed so as to be perpendicular to the current direction. The occurrence of Barkhausen noise is a problem in the soft magnetic layer 6 in which the magnetization direction changes.

Here, in the present embodiment, the anisotropic magnetic field of the soft magnetic layer 6 is set so as to be in the range of 20 to 50 [Oe]. Therefore, even if the magnetic flux flowing into the soft magnetic layer 6 from the hard bias layer 9a flows into the lower shield layer 3 and the upper shield layer 11, the anisotropic magnetic field of the soft magnetic layer 6 is large. Can be kept constant. As a result, generation of Barkhausen noise can be suppressed.

The soft magnetic layer 8a may be composed of a plurality of layers made of different materials, for example, a CoFe film, a Co film,
It may be composed of at least one of the CoFeB film and two layers of the NiFe film.

A method for manufacturing a magnetoresistive sensor according to the present invention having the above-described structure (particularly, a structure in which the anisotropic magnetic field of the soft magnetic layer 6 is set to be in the range of 20 to 50 [Oe]). A preferred embodiment of the present invention is as follows. First, a substrate protection layer 2 is formed on the entire upper surface of the Altic substrate 1 using alumina. Then, sendust is sputtered on the substrate protective layer 2 to form the lower shield layer 3,
A lower insulating layer 4 made of alumina is formed on the upper surface of the lower shield layer 3.
To form Up to this point, it is the same as the method of manufacturing the conventional magnetoresistive sensor.

Next, at a predetermined position on the upper surface of the lower insulating layer 4,
A spin valve film 5 is formed. The configuration (material and film thickness) of the spin valve film 5 was as shown in Table 1 below.

[0032]

[Table 1]

The film forming conditions for each layer at this time were as shown in Table 2 below.

[0034]

[Table 2]

Here, the present embodiment is characterized in the step of forming the soft magnetic layer 6 constituting the spin valve film 5. The soft magnetic layer 6 is formed by applying a soft magnetic material to the upper surface of the lower insulating layer 4 by sputtering while applying a magnetic field in a certain direction. This is the same as the conventional case. Here, in the present invention, the sputter deposition for forming the soft magnetic layer 6 is performed by oblique deposition.

That is, as shown in FIG. 2, the substrate 1 formed up to the lower insulating layer 4 is washed with a predetermined solvent.
Next, when the soft magnetic layer 6 is formed on the surface of the substrate 1, the target 20 for forming the soft magnetic layer 6 is formed on the substrate 1 (since each layer is formed with a uniform thickness, the substrate 1 The parallelism between the surface of the lower magnetic pole layer 4 and the surface of the lower magnetic pole layer 4 on the surface to be formed can be considered to be maintained, so that the substrate is easily taken as a reference surface. The target 20 is arranged such that an axis connecting the center of the target 20 and the center of the substrate 1 forms an angle α. At this time, it is set so that the surface of the target 20 and the surface of the substrate 1 are parallel. Sputtering is performed in this state, and the substrate 1
The soft magnetic layer 6 is formed on the surface (surface of the lower gap layer 4) by oblique film formation.

Next, a nonmagnetic layer 7, a soft magnetic layer 8a, an antiferromagnetic layer 8b, and a protective cap layer are sequentially formed on the upper surface of the soft magnetic layer 6 so as to have a predetermined thickness. At this time, each layer is formed directly above, that is, at an angle α of 0 degrees. The manufacturing process for the non-magnetic layer 7 and thereafter is the same as the conventional one. And
After laminating each layer, it is patterned into a shape as shown in FIG.

Thereafter, the hard bias layer 9a is brought into contact with both sides of the spin valve film 5 with respect to the sliding surface of the recording medium.
To form The hard bias layer 9a is made of CoCrPt.
To form a permanent magnet. Then, an electrode layer 9b is formed on the upper surface of the hard bias layer 9a using gold or the like. Further, the spin valve film 5 and the hard bias layer 9
a, a normal semiconductor process such as forming an upper insulating layer with an insulator such as alumina on the surface of the electrode layer 9b and forming an upper shield layer on the upper surface of the upper insulating layer, thereby obtaining a magnetoresistive head. To manufacture.

In order to confirm the effect of the magnetoresistive head manufactured by the above-described method of manufacturing the magnetoresistive head, the anisotropy of the soft magnetic layer 6 was adjusted by adjusting the angle α of the target arrangement in oblique film formation. The strength of the magnetic field was adjusted, and the correlation between the strength of the anisotropic magnetic field and the occurrence rate of Barkhausen noise was examined.

The angle α is changed from 0 degree (conventional method) to 55 degrees, and 50 samples (manufactured magnetoresistive heads) are formed for each angle. The strength (Hk) of the anisotropic magnetic field and the MR ratio are characteristic values of the spin valve film, and are measured by a four-terminal method in a state where each layer constituting the spin valve film is entirely sputtered (before patterning). . The occurrence rate of Barkhausen noise (BHN) was measured based on a magnetoresistive head having an upper shield layer formed thereon. The results are shown in Table 3 below.
The hard bias layer has a residual magnetic flux density Br = 550.
A 0 Gauss CoCrPt film was used, and its thickness T was made equal to a value obtained by multiplying the saturation magnetic flux density Bs of the soft magnetic layer by the film thickness (120 Å). Since Bs of the soft magnetic layer NiFe is 10,000 Gauss, the following equation is satisfied from the above conditions. Therefore, the thickness of the hard bias layer is set to 220 angstroms. 10,000 * 12
0 = 5500 * TT = 220 [Angstrom]

[0041]

[Table 3]

As is clear from the experimental results shown in Table 3, as the angle α increases, the strength Hk of the anisotropic magnetic field of the soft magnetic layer 5 increases. And, as Hk increases,
It can be seen that the occurrence rate of Barkhausen noise decreases, and when Hk becomes 20 [Oe] or more (α = 30 degrees or more), no Barkhausen noise is generated.

Hk is 55 or more (α = 52 degrees or more)
Then, the MR ratio decreases. Therefore, in order to reduce the Barkhausen noise while maintaining the MR ratio equal to the conventional one, the strength Hk of the anisotropic magnetic field of the soft magnetic layer 6 must be 2
It is preferably in the range of 0 to 50 [Oe], and more preferably in the range of 30 to 50 [Oe] because Barkhausen noise can be eliminated. Of course, if attention is paid to eliminating Barkhausen noise, it may of course be 50 [Oe] or more. That is, the present invention is not limited to 50 [Oe] or less, but may be an anisotropic magnetic field strength of more than 50 [Oe].

FIG. 3 is a view for explaining the structure of a spin valve film, which is a main part of a second embodiment of the magnetoresistive head according to the present invention. The present embodiment is characterized in that an underlayer is formed below the soft magnetic layer 6 constituting the spin valve film 5 as compared with the structure of the magnetoresistive head according to the first embodiment. Also in this embodiment, the anisotropic magnetic field of the soft magnetic
By setting the soft magnetic layer 6 within the range of 50 [Oe], the soft magnetic layer 6 is made into a single magnetic domain. Since the other configuration and operation and effect are the same as those of the above-described first embodiment, the same reference numerals are given and the detailed description is omitted.

A method for manufacturing the magnetoresistive head having the above-described structure will be described. As shown in the drawing, a Ta film is formed by oblique film formation on the upper surface of the lower insulating layer 4 formed above the Altic substrate, so that the underlayer 30 is formed. This oblique film forming step can be performed by the same process as in the first embodiment, only by changing the type of the target.

Except for the step of forming the underlayer 30, each layer is formed and formed by a process similar to the conventional one. That is, the soft magnetic layer 6 itself was formed at an incident angle α of 0 °, such as a film directly above, as in the conventional case. Even if the soft magnetic layer 6 is formed at an angle α of 0 °, the underlayer 3
Since 0 is already formed by oblique film formation, the crystal structure of the soft magnetic layer 6 formed on the upper surface thereof is affected by the base film 30 and grows obliquely. Therefore, the anisotropic magnetic field of the soft magnetic layer 6 increases. The magnitude of the anisotropic magnetic field depends on the angle α of the oblique film formation for forming the underlayer 30.
Can be controlled by controlling

The thickness of each layer and the material for forming each layer were the same as those in the first embodiment. The thickness of the underlayer 30 newly added in the second embodiment was set to 50 Å. Then, an incident angle α of the underlayer 30 is changed to produce a magnetoresistive head, and the underlayer 30 at that time is formed.
The relationship between the strength (Hk) of the anisotropic magnetic field of the soft magnetic layer 6, the MR ratio, and the incidence of Barkhausen noise of the magnetoresistive head with respect to the angle α of the oblique film formation was obtained. The film formation conditions and evaluation method at this time were the same as those in the first embodiment. The results are shown in Table 4 below.

[0048]

[Table 4]

As shown in Table 4 above, as the deposition angle α of the underlayer 30 increases, the strength Hk of the anisotropic magnetic field of the soft magnetic layer 6 also increases. Then, it turns out that the incidence of Barkhausen noise is reduced. In particular, when Hk is 20 or more, Barkhausen noise does not occur. When Hk becomes 52 [Oe] (when Hk exceeds 50 [Oe]), the MR ratio becomes 2.2%, and the characteristics of the head deteriorate. Therefore, Hk is 20 to 5
In the state of 0 [Oe], it is possible to suppress the occurrence rate of Barkhausen noise while improving the characteristics of the magnetoresistive head. Of course, as in the first embodiment,
Focusing on Barkhausen noise, Hk may be larger than 50. That is, the incident angle α at the time of oblique film formation is 50
It may be larger than the degree.

Next, in the case where the underlayer 30 is formed directly above the incident angle α = 0 without forming the oblique film and the soft magnetic layer 6 is formed obliquely, the anisotropy of the soft magnetic layer An experiment was conducted to investigate how the magnetic field and Barkhausen noise occurrence rate change. The results are shown in Table 5 below.

[0051]

[Table 5]

From the above Table 5, it can be seen that even when the film forming angle α of the soft magnetic layer 6 is changed, the intensity Hk of the anisotropic magnetic field hardly changes. This is presumably because the crystal structure of the soft magnetic layer 6 is affected by the underlayer 30. Since the intensity Hk of the anisotropic magnetic field hardly changes, even if the angle α of the oblique film formation of the soft magnetic layer 6 changes, the occurrence rate of Barkhausen noise is high (88 to 88).
90%).

From the results of the above two experiments, when the underlayer 30 is formed on the lower surface of the soft magnetic layer 6 constituting the spin valve film 5, in order to suppress the occurrence rate of Barkhausen noise, It is understood that it is necessary to form the film 30 obliquely.

Further, in this embodiment, an experiment was conducted to examine characteristics such as the incidence of Barkhausen noise when the structure of the soft magnetic layer was changed. That is, the soft magnetic layer 6 was formed by laminating a 30 Å CoFe film on a 90 Å NiFe film. Further, a soft magnetic layer 8a is formed on a 30 Å
It was formed by laminating a 0 Å NiFe film.
Each of the CoFs constituting the soft magnetic layer 6 and the soft magnetic layer 8a
The e film is sputtered by using a DC magnetron as a power source, and has a film formation rate of 0.6 [angstrom / sec]. The materials and thicknesses of the other layers were the same as those in the second embodiment.

Then, the change of the strength Hk and MR ratio of the anisotropic magnetic field of the adjusted soft magnetic layer 6 of the magnetoresistive head manufactured by changing the angle α of the oblique film formation of the underlayer, I examined the incidence of Barkhausen noise. The results are shown in Table 6 below.

[0056]

[Table 6]

From Table 6 above, it can be seen that the intensity Hk of the anisotropic magnetic field is
Is not less than 20 [Oe] (when the angle α of the oblique film formation is not less than 25 degrees), it was found that no Barkhausen noise was generated. When the strength Hk of the anisotropic magnetic field is 10 [O
e] (ie, when the angle α of the oblique film formation is 0 °, as in the conventional method of manufacturing a magnetoresistive head), the MR
While the ratio is 8%, when Hk is 64 [Oe] or more (when α = 52 degrees or more), the MR ratio decreases to 6%, and the characteristics of the head deteriorate. You can see that. Therefore, even if the structure of the soft magnetic layer 6 is changed,
The strength Hk of the anisotropic magnetic field is 20 to 49 (about 50) [Oe]
It is desirable to adjust to. Also in this case, if attention is paid only to the suppression of the generation of Barkhausen noise, the effect is exhibited even when the intensity of the anisotropic magnetic field is higher.

Further, based on the above-mentioned modified example (an example in which the soft magnetic layer has a two-layer structure), the underlayer was manufactured by changing the material to Zr, and the characteristics were obtained. That is, Zr was sputtered using an RF magnetron as a power source at a film formation rate of 1.2 [angstrom / sec] to form an underlayer. Then, magnetoresistive heads were manufactured using the underlayers in which the angle α of the oblique film formation was changed during sputtering. At this time, the change in the strength Hk and MR ratio of the anisotropic magnetic field of the soft magnetic layer and the occurrence rate of Barkhausen noise at that time were examined. The results are shown in Table 7 below.

[0059]

[Table 7]

From Table 7 above, it can be seen that the intensity Hk of the anisotropic magnetic field is
Is not less than 20 [Oe] (when the angle α of the oblique film formation is not less than 15 degrees), it was found that no Barkhausen noise was generated. Then, the strength Hk of the anisotropic magnetic field is 17 [O
e] (ie, when the angle α of the oblique film formation is 0 °, as in the conventional method of manufacturing a magnetoresistive head), the MR
While the ratio is 7.8%, when Hk is 62 [Oe] (when α = 45 degrees), the MR ratio decreases to 5.4%, and the characteristics of the head deteriorate. It turns out that it is. Therefore, even when the material for forming the underlayer is changed, it is desirable to adjust the strength Hk of the anisotropic magnetic field to 20 to 47 [Oe].
It can be seen that generation of Barkhausen noise can be suppressed while maintaining good head characteristics.

[0061]

As described above, in the magnetoresistive head according to the first and third aspects, by setting the anisotropic magnetic field of the soft magnetic layer constituting the spin valve film to 20 [Oe] or more, the Barkhausen Generation of noise can be suppressed as much as possible. In particular, by setting the value in the range of 20 to 50 [Oe], Barkhausen noise can be suppressed while improving the characteristics (MR ratio) of the magnetoresistive head.

In the method of manufacturing a magnetoresistive head according to the second aspect, when a spin valve film (a soft magnetic layer constituting the spin valve film) is formed directly on the upper surface of the lower insulating layer,
By forming the soft magnetic layer obliquely, by adjusting the angle of the oblique film formation at that time, the anisotropic magnetic field of the soft magnetic layer can be adjusted.

In the method of manufacturing a magnetoresistive head according to a fourth aspect, when a spin valve film (a soft magnetic layer constituting the spin valve film) is formed on an upper surface of a lower insulating layer via an underlayer, The anisotropic magnetic field of the soft magnetic layer formed on the upper surface of the underlayer can be controlled by adjusting the angle of the oblique film formation at that time by forming the oblique film on the base layer.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a magnetoresistive sensor unit in a first embodiment of a magnetoresistive head according to the present invention.

FIG. 2 is a diagram for explaining a method of forming a film obliquely.

FIG. 3 is a diagram showing a structure of a magnetoresistive sensor unit in a second embodiment of the magnetoresistive head according to the present invention.

FIG. 4 is a diagram showing a magnetic flux flowing through a magnetoresistive film in a magnetoresistive head manufactured by a conventional method of manufacturing a magnetoresistive head.

FIG. 5 is a view for explaining a single magnetic domain structure of a magnetoresistive film in which a hard bias layer is arranged at an end in a magnetoresistive head manufactured by a conventional method of manufacturing a magnetoresistive head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Altic substrate 3 Lower shield layer 4 Lower gap layer 5 Spin valve film 6 Soft magnetic layer 7 Nonmagnetic layer 8a Soft magnetic layer 8b Antiferromagnetic layer 9a Hard bias layer 9b Electrode layer 20 Target 30 Underlayer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaru Tosho 5-36-11, Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Inventor Makoto Ishikura 5-36-11, Shimbashi, Minato-ku, Tokyo F-term in Fuji Electric Chemical Co., Ltd. (reference) 5D034 BA02 BA12 BA15 BB09 CA04 DA07

Claims (4)

[Claims] 1. A lower shield layer (3) on a substrate (1).
A lower insulating layer (4) is provided in that order, and a spin valve film (5) composed of a soft magnetic layer (6), a non-magnetic layer (7), and a fixed layer (8) is provided on the upper surface of the lower insulating layer. A magnetoresistive head comprising: a hard bias layer formed on a side of the spin valve film; and an upper insulating layer and an upper shield layer on the spin valve film, the upper surface of the hard bias layer in that order. A magnetoresistive head, wherein an anisotropic magnetic field of the soft magnetic layer is set to 20 [Oe] or more. 2. A lower shield layer is formed directly or via a predetermined layer on an upper surface of a substrate, a lower gap layer is formed on an upper surface of the lower shield layer, and a soft magnetic layer and a non-magnetic layer are formed on an upper surface of the lower gap layer. Forming a spin valve film by laminating a layer and a fixed layer in this order, patterning a hard bias layer on the side of the spin valve film, forming an upper insulating layer on the upper surface of the spin valve film and the hard bias layer, A method for manufacturing a magnetoresistive head including a step of forming an upper shield layer on an upper surface of the upper insulating layer, wherein the soft magnetic layer is formed by oblique film formation in which atoms are incident on a film formation surface at a predetermined angle. A method for manufacturing a magnetoresistive head. 3. A lower shield layer (3) on a substrate (1).
A lower insulating layer (4) is provided in that order, a base layer (30) is formed on the upper surface of the lower insulating layer, and a soft magnetic layer (6), a nonmagnetic film (7), and a fixed layer (8) are stacked in this order. A hard bias layer (9) formed on a side of the spin valve film, and an upper insulating layer and an upper shield layer on the spin valve film and the hard bias layer. Wherein the anisotropic magnetic field of the soft magnetic layer is set to 20 [Oe] or more. 4. A lower shield layer is formed directly or via a predetermined layer on an upper surface of the substrate, a lower gap layer is formed on an upper surface of the lower shield layer, and a base layer is formed on an upper surface of the lower gap layer. Forming a spin valve film by laminating a soft magnetic layer, a non-magnetic layer, and a fixed layer in this order on the upper surface of the underlayer; patterning a hard bias layer on a side of the spin valve film; A method for manufacturing a magnetoresistive head, comprising: forming an upper insulating layer on an upper surface of a hard bias layer; and forming an upper shield layer on an upper surface of the upper insulating layer. A method for manufacturing a magnetoresistive head, wherein the head is formed by oblique film formation in which atoms are incident from a predetermined angle of inclination.